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Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study
Trends in Anaesthesia and Critical Care xxx (2017) 1e8
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Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study Semhar Ghebremichael a, Sam D. Gumbert a, Naveen Vanga a, Omar L. Mancillas a, Tyrone Burnett Jr. a, Chunyan Cai b, Carin A. Hagberg a, * a
Department of Anesthesiology, The University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School, 6431 Fannin St., MSB 5.020, Houston, TX, 77030, USA Department of Internal Medicine, The University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School, 6410 Fannin St., UPB 1100.08, Houston, TX, 77030, USA
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 27 June 2017 Received in revised form 16 September 2017 Accepted 28 September 2017
Background: One of the biggest challenges for anesthesia practitioners during airway management is the maintenance of adequate oxygenation and ventilation during difficult and emergency airway situations. Providing nasal ventilation during the “apneic period”, defined as the time between the end of bag-mask ventilation and successful placement of an appropriate airway device, may allow for improved oxygenation throughout the process in which the airway is secured. The SuperNO2VA™ mask (Revolutionary Medical Devices, USA) is a newly developed nasal mask that delivers non-invasive positive pressure nasal ventilation that is designed to provide continuous oxygenation and ventilation during anesthetic induction until the airway is secured. Aim: The purpose of this study was to evaluate the clinical performance of the SuperNO2VA™ mask for nasal oxygenation and ventilation during pre-induction, post-induction, laryngoscopy, and tracheal intubation in adult patients requiring general anesthesia. Methods: Following IRB/ethical board approval and written informed consent, 30 adult patients, ages 18 years or older, with an ASA status I-III, who were scheduled for an elective surgery that required general anesthesia and tracheal intubation, were enrolled into this study. Patient demographic characteristics and intervening outcomes were all recorded. The SuperNO2VA™’s efficacy was evaluated by the measurement and recorded values of peak airway pressures, tidal volumes, minimal oxygen saturation values (while the airway was secured), as well as, an objective assessment grading scale for mask ventilation. The time required to secure the airway, including laryngoscopy, was also recorded. Results: The SuperNO2VA™ nasal mask provided adequate oxygenation and successful ventilation in 29 of 30 patients, resulting in an overall success rate of 97% (95% confidence interval: 83%e100%). One patient was unable to be successfully ventilated by the SuperNOVA™ mask and was noted a Grade IV. The mean duration of laryngoscopy was 50.7 ± 23.2 s, with an average SpO2 of 99.6 ± 0.8% calculated for this interval. The lowest observed SpO2 for the 29 patients at preoxygenation, pre-induction, pre-ETT insertion, during laryngoscopy, post-intubation, and in the PACU was 95, 97, 97, 97, 98, and 94%, respectively. The average for the lowest SpO2 during the entire airway procedure was 98.1 ± 7.0%. And the average peak airway pressure, for all 29 patients, was 17.97 ± 3.95 mmHg, with a mean tidal volume of 573.7 ± 40.7 mL. Conclusion: This observational study demonstrated that the SuperNO2VA™ mask facilitates non-invasive positive pressure ventilation while providing adequate oxygenation and ventilation during preinduction, post-induction, laryngoscopy, and tracheal intubation in elective surgical patients. Conversely, considering the novelty of this particular study, further research is warranted to determine its usefulness in patients with known/predicted difficult airways, or even during emergent situations. Published by Elsevier Ltd.
Keywords: Airway management Apneic oxygenation Nasal ventilation Non-invasive positive pressure ventilation Safe apneic period Supplemental oxygen
* Corresponding author. Present Address: The University of Texas MD Anderson Cancer Center, Division of Anesthesiology, Critical Care & Pain Medicine, 1400 Holcombe Blvd., Unit 409, Houston, TX 77030, USA. E-mail addresses: [email protected] (S. Ghebremichael), [email protected] (S.D. Gumbert), [email protected] (N. Vanga), [email protected] (O.L. Mancillas), [email protected] (T. Burnett), [email protected] (C. Cai), [email protected] (C.A. Hagberg). https://doi.org/10.1016/j.tacc.2017.09.054 2210-8440/Published by Elsevier Ltd.
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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S. Ghebremichael et al. / Trends in Anaesthesia and Critical Care xxx (2017) 1e8
1. Introduction
2. Materials and methods
One of the biggest challenges for anesthesia practitioners during airway management is the maintenance of adequate oxygenation and ventilation when a difficult airway is encountered. Previous studies have investigated several options/techniques that may help prolong, and possibly prevent, desaturation; however, these specific techniques do not eliminate the critical apneic period, altogether [1e3]. The Difficult Airway Society (DAS) created guidelines for managing difficult airways with several techniques and tips to optimize oxygenation and ventilation prior to intubation, but there is no mention of ventilation during the period of laryngoscopy and tracheal intubation in the most recent American Society of Anesthesiologist's (ASA's) guidelines [4]. Intravenous (IV) deep sedation and the induction of general anesthesia cause respiratory compromise by fundamentally affecting the chemical, neurological, and mechanical regulation of ventilation. It is this sequence of events that induces upper airway obstruction and respiratory depression that may subsequently cause hypoventilation, atelectasis, and ultimately oxygen desaturation leading to hypoxemia [2e6]. Certain patient populations (i.e. pediatric, obese, and obstetric) are considered ‘at (high) risk’ for rapid desaturation after the induction of general anesthesia. Causes are due to increased oxygen consumption, reduced functional residual capacity (FRC), and/or poor oxygen reserve that hasten the development of hypoxemia [1e6]. In current clinical practice, it is common that pre-oxygenation is performed with 100% FiO2 for approximately 3 min, and patients are instructed to breathe deeply to help establish a safe apneic period [1]. Extending the safe apneic period, or the time between the onset of apnea until end-tidal oxygen (EtO2) percentage reaches 90% or less, increases the patient's margin of safety [1,4]. Further maneuvers are indicated in high-risk patients for optimal preoxygenation. Positive pressure ventilation and 25 ramped up positioning are recommended for obese patients [7] and may be useful in all patients. ICU patients have maximal benefit from noninvasive ventilation (NIV) [8,9], when coupled with high flow nasal cannula (HFNC) [10], while extension of safe apnea time can be granted with apneic oxygenation techniques, such as nasal oxygen during efforts securing a tube (NODESAT, usually with a nasal cannula) [1,11] or HFNC [12]. The SuperNO2VA™ (Revolutionary Medical Devices, Inc., Tucson, AZ, USA) is a newly developed nasal mask that delivers noninvasive positive pressure ventilation through the nasal route to provide continuous oxygenation and ventilation during anesthetic induction and throughout laryngoscopy. The SuperNO2VA™ mask was designed to create a seal, deliver gas, and generate positive pressure, allowing for continuous nasal oxygenation and ventilation during sedation, by placement over the patient's nose and connection to a gas source, so that positive pressure builds up inside the mask (Fig. 1). This pressure, therefore, helps separate the soft palate from the posterior pharygeal wall and forces oxygen to flow from the nose to the lungs. The purpose of this study was to determine the clinical performance of SuperNO2VA™ technology post induction, as measured by the average lowest oxygen saturation (SpO2), peak airway pressures and tidal volumes, average end-tidal of carbon dioxide (EtCO2), and average objective ventilation scale grades, as previously described by Han R., et al. [13]. SuperNO2VA™ safety and tolerability were secondary objectives that consisted of technical performance, indicated by the incidence and nature of adverse events (AEs), serious adverse events (SAEs), unanticipated adverse device effects (UADEs) and their duration, resolution and required treatment, if any, along with the time required to secure the airway during laryngoscopy.
After approval of the protocol by the Institutional Review Board (IRB) of the University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School and the Research Committee of the Department of Anesthesiology, 30 adult patients scheduled for elective surgery at Memorial Hermann HospitaleTexas Medical Center were recruited to participate in this non-randomized, observational, prospective study. Key research personnel, such as the principal investigator, co-investigator, and/or study coordinators, obtained informed consent preoperatively. Each eligible patient was provided with a detailed explanation of the study's purpose and their role as a participant by both oral and written communications. All protected health information (PHI) was secured in an encrypted database in accordance with the Health Insurance Portability Accountability Act of 1996 (HIPAA). The study period consisted of 3 months from February through April 2016. 2.1. Patient selection The study's cohort was comprised of individuals scheduled to undergo surgery that met the following inclusion criteria: (1) age of 18 years old or older, and (2) American Society of Anesthesiology (ASA) physical status I-III. Exclusion criteria consisted of the following: (1) any presence of an underlying neuromuscular disease, (2) use of medications known to interfere with neuromuscular transmission, (3) history of cervical spine injury or cervical pathology, (4) presence of renal or hepatic disease, and (5) inability to fit the mask. Morphometric characteristics, such as neck circumference, inter-incisor gap, thyromental distance, and sternomental distance were measured and recorded for all patients. The quality of each patient's airway was evaluated using the physical examination recommendations in the most recent American Society of Anesthesiologist's (ASA) “Practice Guidelines for Management of the Difficult Airway” [14]. Also, a review of previous airway management history was obtained, including, history of snoring, diagnosis of obstructive sleep apnea (OSA), anticipated difficult-mask-ventilation (DMV), laryngoscopy, or intubation, as well as, any history of DMV, difficult laryngoscopy or intubation, presence of facial hair, body mass index (BMI) > 30 kg/m2, elderly (>55 years old), and/or edentulous. 2.2. Study procedure Each patient received general anesthesia and was intubated by either direct or video laryngoscopy. In the operating room (OR), standard monitoring devices were applied, including a pulse oximeter, 3-lead electrocardiogram, and blood pressure monitoring (in which the latter may be invasive or non-invasive). Measures of blood pressure, heart rate, respiratory rate, SpO2, and EtCO2 were observed and recorded before the patient's surgical preparation, and periodically while the airway was being secured. Vital signs were recorded immediately before oxygen administration, before induction of anesthesia, before ETT insertion, during laryngoscopy, after ETT insertion, and postoperatively during the participant's recovery in the post-anesthesia care unit (PACU). Study providers included attending anesthesiologists, resident anesthesiologists, anesthesiologist assistants, and an anesthesiologist assistant student. The SuperNO2VA™ mask is intended to facilitate simultaneous oxygenation and ventilation through the nose, allowing the clinician to have an unobstructed view of the airway during laryngoscopy, intubation, and/or procedures requiring access to the oral cavity (Fig. 2). Only an “Adult Large” size of the SuperNO2VA™ mask was used during the study period. This was largely due to the
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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Fig. 1. The SuperNO2VA™ mask.
manufacture's limited development of other various sizes during the trial (SuperNO2VA™ mask sizing is based on height, not weight; an “Adult Large” recommended height range is 180e220 cm). Study personnel prepared and assembled the SuperNO2VA™ mask before each patient entered the OR. The original, standard, facemask was removed from the mechanical ventilator, via anesthesia circuit, and was replaced with the SuperNO2VA™ mask for oxygen administration. The end-tidal CO2 monitor and tubing were attached to the SuperNO2VA™ mask to ensure whether or not the subject was being ventilated prior to laryngoscopy. Once the SuperNO2VA™ mask was securely assembled, the anesthesia practitioner was able to provide oxygen and/or ventilation the patient prior to induction, during induction, post induction, laryngoscopy, and intubation. Before anesthesia induction, the SuperNO2VA™ mask was placed and secured onto the patient's nose, utilizing its prepackaged Velcro straps, and was assessed for comfort ability and tolerability through verbal communication and subjective assessment. General anesthesia was then induced by intravenous administration of propofol (1.5e2 mg/kg) and fentanyl (1 mcg/kg) and maintained with an inhalation agent. Rocuronium (0.6 mg/kg) was administered to induce muscle relaxation. The lungs were mechanically ventilated with a semi-closed circle system to maintain an end-tidal CO2 near 35 mmHg. Ventilation was maintained via SuperNO2VA™ mask with 100% oxygen administration, until the patient was completely relaxed (0 on train of four on twitch monitor). The anesthesia practitioner then attempted to ventilate the patient with the SuperNO2VA™ mask. If the anesthesia practitioner was able to ventilate the patient based on the following observations/indications: fogging of the SuperNO2VA™ mask, chest rise
and fall of the patient, measured EtCO2 waveform capnography, and/or lung auscultation, then the patient was placed on pressurecontrolled ventilation at a pressure of 20 mm H2O, PEEP of 10 cm H2O, with a respiratory rate of 12 breaths per minute (suggested manufacturer settings), and a FiO2 flow setting of 30 L/min with 100% oxygen. If the anesthesia practitioner could not ventilate the patient with the SuperNO2VA™ mask, the device was deemed a failure and the patient was ventilated with the standard facemask instead. With the SuperNO2VA™ mask appropriately secured to the patient and allowing adequate mechanical ventilation, the anesthesia practitioner then attempted to perform laryngoscopy and tracheal intubation with the SuperNO2VA™ attached to the patient. During the entire airway procedure, research personnel recorded the lowest SpO2 during the airway procedure, peak airway pressures, and tidal volumes while the SuperNO2VA™ was used. After the airway was secured, the anesthesia practitioner discontinued their use of the SuperNO2VA™ mask, which concluded the research intervention. As a result, a classification grade was then reported by the study anesthesiologist, signifying the SuperNO2VA™’s ability to mask ventilate (Fig. 3) [13]. For study purposes, adverse events were categorized into 2 groups: (1) Serious Adverse Events (SAE), and/or (2) Non-Serious Adverse Events (NSAEs). The causal relationship of each AE was assessed by the Principal Investigator (PI) as either, related to the device (including its deployment), or not related to the device (including its deployment). Furthermore, each AE that was classified as being related to the device (including its deployment), would then be determined as being either anticipated or unanticipated, by the PI. Recognized risks associated with the use of the SuperNO2VA™ mask included, but was not limited to, the
Fig. 2. Three plausible applications of the SuperNO2VA™ mask for its intended use; (left) during laryngoscopy, (middle) during a rescue setting with the assistance of fiberoptics, and (right) nasal ventilation.
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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Fig. 3. Han et al. [12] classification scale used for assessing the SuperNO2VA™ mask Ease of Use.
following: (1) allergic reactions, (2) skin abrasions, (3) pressure ulcers, and/or (4) ocular injury. Patient safety was defined by the incidence and nature of AEs, SAEs, NSAEs, or UADEs and their duration; this also included their respective resolutions and required treatments, as a result from the utilization of the SuperNO2VA™ mask during the interventional study period. Patient tolerability was defined as complete removal and discontinued use of the SuperNO2VA™ mask due to any of the following physical observations, including mask irritation, mask discomfort, and/or mask displacement. 2.3. Statistical methods Data was summarized as mean ± standard deviation (mean ± SD) for continuous variables with normal distribution and median (interquartile range) with non-normal distribution, along with frequency and percentage for categorical variables. The percentage of successful ventilation, as well as its 95% confidence interval, was calculated. All analyses were performed using SAS 9.4 (Cary, NC). We enrolled 30 human subjects into this study. Using binomial staged sampling, this sample size is expected to identify ventilation failures (1 or fewer cases) with a 0.95 confidence limit and a 0.25 upper confidence level.
3.1. Patient demographics and characteristics Table 1 summarizes patient demographics and other clinical variables for all 30 patients, in accordance with their respective ventilation grade. Analysis of the demographics for the 30 patients revealed a heterogeneous population of 19 males and 11 females, aged 46.3 ± 17.2 years, with 10 patients >55 years of age. Of the elderly patients, only one was edentulous. Of the males that were successfully ventilated, only 3 were considered “clean shaven”, the rest presented with stubble, goatee, mustache, and/or beard. Of the patients with a pertinent past medical history, 11 presented with a history of snoring, 7 with OSA, 4 with anticipated DMV, and none with a history of DMV, laryngoscopy, or intubation. Eighteen patients presented with a BMI >30 kg/m2, with a mean BMI of 34.1 ± 9.9 kg/m2. All patients ranged with Mallampati classifications I-III; Mallampati I (14), Mallampati II (11), and Mallampati III (5). Morphometric characteristics included the following difficult airway predictors for tracheal intubation: neck circumferences >41 cm (female) and >43 cm (male), inter-incisor gap distances <4 cm, thyromental distances <6 cm, and sternomental distances <12 cm. Only 2 males and 2 females presented with 2 predictors, while all the other patients had either one or none of the suggested difficult airway predictors. 3.2. Oxygenation and ventilation with the SuperNO2VA™
3. Results Pulmonary ventilation by the SuperNO2VA™ mask was successful in 29 of the 30 patients (97%) during the securement of their airways. Six patients with a ventilation Grade II required placement of a nasal airway adjuvant (i.e. nasal trumpet) to facilitate adequate nasal mask ventilation. One patient received a ventilation grade of III since 2 providers were required to achieve successful ventilation. The anesthesiologist experienced difficulty creating a seal at the lips after the administration of muscle relaxant, necessitating 2 hands to manipulate the SuperNO2VA™ mask, along with the patient's mouth, while the other provider squeezed the oxygen reservoir bag for manual ventilation. A ventilation Grade IV was obtained in 1 patient due to the inability to provide adequate and effective nasal mask ventilation. After intravenous induction, the attending anesthesiologist determined that he was not able to mask ventilate by the absence of EtCO2, no mask condensation, in addition to no chest movement. Although this patient did not experience any oxygen desaturation during the interventional period, the provider switched to the standard full-face mask for ventilation before allowing additional attempts to ventilate with the SuperNO2VA™ mask. This particular case was deemed a failure and was only included in the analysis of patient demographics, as no values related to its clinical performance were recorded. This particular failure may have been attributed to user error, as the mask does require a modified grip when creating a sufficient seal on the patient's nose and mouth for effective positive pressure nasal ventilation. Although Cormack-Lehane (C-L) classification was not recorded as a pertinent data point, there were no difficult intubations during the study period.
Twenty-eight patients were assessed with either a ventilation Grade I or II (93.3%), and only one patient was assessed as a Grade III, requiring additional assistance. One patient received a Grade IV for unsuccessful nasal ventilation and was deemed a failure. The SuperNO2VA™ nasal mask provided satisfactory oxygenation and ventilation in 29 of 30 patients, resulting in an overall success rate of 97% (95% confidence interval: 83%e100%). Collectively, 22 patients (73.3%) were assessed with a ventilation Grade I, 6 patients (20%) were assessed with a ventilation Grade II, 1 patient (3.3%) was assessed with a ventilation Grade III, and 1 patient (3.3%) was assessed with a ventilation Grade IV. Also, 20 patients (66.7%) were intubated via direct laryngoscopy versus 10 patients (33.3%) that were intubated via indirect (video) laryngoscopy. Table 2 summarizes the vital signs for the 29 patients with ventilation Grades I-III. Systolic (110.2 ± 22.0 mmHg) and diastolic (68.0 ± 15.8 mmHg) blood pressures remained stable throughout the study and trended accordingly with the onset, maintenance and discontinuation of general anesthesia. Heart rates for the 29 patients throughout the study remained stable with an average of 76.8 ± 15.0 beats per minute during laryngoscopy. Respiratory rates for all included patients also remained stable with an average of 10.0 ± 3.7 breaths per minute. The 29 patients successfully ventilated by SuperNO2VA™ nasal mask were all intubated on the first attempt. The mean duration of laryngoscopy was 50.7 ± 23.2 s, with an average SpO2 of 99.6 ± 0.8% calculated for this interval. The lowest observed SpO2 for the 29 patients at preoxygenation, pre-induction, pre-ETT insertion, during laryngoscopy, post-intubation, and in the PACU was 95, 97, 97, 97, 98, and 94%, respectively. Oxygen saturation <92% did not occur.
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
S. Ghebremichael et al. / Trends in Anaesthesia and Critical Care xxx (2017) 1e8
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Table 1 Summary statistics of demographics, baseline morphometric characteristics, and anesthetist levels in all 30 patients (in both Table's 1a and 1b). a. Summary of demographics, morphometric characteristics, and anesthetist levels.
Age (in years), mean ± SD Gender, no. (%) Female Male Body Mass Index (BMI) (kg/m2), mean ± SD Height (cm), mean ± SD Weight (kg), mean ± SD Inter-incisor gap distance (cm), mean ± SD Neck circumference (cm), mean ± SD Thyromental distance (cm), mean ± SD Sternomental distance (cm), mean ± SD Mallampati Class., no. (%) 1 2 3 Anesthetist level, no. (%) Attending anesthesiologist CA-1 CA-2 CA-3 Anesthesiologist assistant (AA) AA student
Total (n ¼ 30)
Ventilation Grade I (n ¼ 22)
Ventilation Grade II (n ¼ 6)
Ventilation Grade III (n ¼ 1)
Ventilation Grade IV (n ¼ 1)
46.3 ± 17.2
41.4 ± 16.7
62.2 ± 7.6
64
43
11 (36.7) 19 (63.3) 34.1 ± 9.9 168.6 ± 11.4 97.7 ± 31.2 4.3 ± 0.7 42.9 ± 5.9 7.9 ± 1.3 14.2 ± 1.9
9 (40.9) 13 (59.1) 33.0 ± 9.7 169.5 ± 12.6 95.7 ± 32.6 4.2 ± 0.6 41.7 ± 5.3 7.9 ± 1.1 14.4 ± 2.0
2 (33.3) 4 (66.7) 35.4 ± 9.1 166.4 ± 5.3 98.9 ± 30.6 4.7 ± 1.1 46.1 ± 7.3 7.3 ± 2.1 13.0 ± 1.9
0 (0.0) 1 (100.0) 31.6 177.8 100 5 43.5 9.5 15
0 (0.0) 1 (100.0) 54.9 154.9 131.82 4.5 50.5 9.5 15
14 (46.7) 11 (36.7) 5 (16.6)
9 (40.9) 9 (40.9) 4 (18.2)
3 (50.0) 2 (33.3) 1 (16.7)
1 (100.0) 0 (0.0) 0 (0.0)
1 (100.0) 0 (0.0) 0 (0.0)
2 (6.7) 4 (13.3) 1 (3.3) 3 (10.0) 19 (63.3) 1 (3.3)
1 (4.5) 2 (9.1) 1 (4.5) 2 (9.1) 16 (72.7) 0 (0.0)
0 2 0 1 2 1
0 0 0 0 1 0
1 0 0 0 0 0
(0.0) (33.3) (0.0) (16.7) (33.3) (16.7)
(0.0) (0.0) (0.0) (0.0) (100.0) (0.0)
(100.0) (0.0) (0.0) (0.0) (0.0) (0.0)
b. Summary of demographics and morphometric characteristics (Cont.). Total (n ¼ 30) Elderly ( 55 years old), no. (%) No 20 (66.7) Yes 10 (33.3) 2 BMI > 30 (kg/m ), no. (%) No 12 (40.0) Yes 18 (60.0) Edentulous, no. (%) No 29 (96.7) Yes 1 (3.3) History of snoring, no. (%) No 19 (63.3) Yes 11 (36.7) Diagnosis of obstructive sleep apnea (OSA), no. (%) No 23 (76.6) Yes 7 (23.3) Anticipated difficult mask ventilation (DMV), no. (%) No 26 (86.6) Yes 4 (13.3) History of DMV, no. (%) No 30 (100.0) Yes 0 (0.0) Beard, no. (%) No 25 (83.3) Yes 5 (16.7) Stubble, no. (%) No 27 (90.0) Yes 3 (10.0) Mustache, no. (%) No 18 (60.0) Yes 12 (40.0) Goatee, no. (%) No 8 (93.3) Yes 2 (6.7) Shaven, no. (%) No 27 (90.0) Yes 3 (10.0) Upper-lip-bite-test (ULBT), no. (%) 1 15 (50.0) 2 7 (23.3) 3 8 (26.7)
Ventilation Grade I (n ¼ 22)
Ventilation Grade II (n ¼ 6)
Ventilation Grade III (n ¼ 1)
Ventilation Grade IV (n ¼ 1)
17 (77.3) 5 (22.7)
2 (33.3) 4 (66.7)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
10 (45.5) 12 (54.5)
2 (33.3) 4 (66.7)
0 (0.0) 1 (100.0)
0 (0.0) 1 (100.0)
22 (100.0) 0 (0.0)
5 (83.3) 1 (16.7)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
14 (63.6) 8 (36.4)
4 (66.7) 2 (33.3)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
16 (72.7) 6 (27.3)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
21 (95.5) 1 (4.5)
4 (66.7) 2 (33.3)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
22 (100.0) 0 (0.0)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
18 (81.8) 4 (18.2)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
20 (90.9) 2 (9.1)
5 (83.3) 1 (16.7)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
14 (63.6) 8 (36.4)
3 (50.0) 3 (50.0)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
21 (95.5) 1 (4.5)
6 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
19 (86.4) 3 (13.6)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
9 (40.9) 7 (31.8) 6 (27.3)
4 (66.7) 0 (0.0) 2 (33.3)
1 (100.0) 0 (0.0) 0 (0.0)
1 (100.0) 0 (0.0) 0 (0.0)
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Table 2 Summary statistics of vital signs for the 29 successfully ventilated patients. Systolic Blood Pressure (mmHg)
Pre-oxygenation Pre-induction Pre-ETT Insertion During Laryngoscopy Post-ETT Insertion Postoperative (PACU)
141.2 138.5 125.9 110.2 113.8
± ± ± ± ±
12.5 16.2 21.2 22.0 24.7
135.1 ± 19.4
Diastolic Blood Pressure (mmHg) 83.9 81.3 74.6 68.0 73.4
± ± ± ± ±
13.0 12.1 13.4 15.8 20.3
76.7 ± 9.5
Heart Rate (Beats/min.)
SpO2 (%)
Respiratory Rate (Breaths/min.)
EtCO2 (mmHg)
75.1 ± 11.0 72 (65, 83) 75.5 ± 13.9 76.8 ± 15.0 88.3 ± 18.2
99 (96, 100) 100 (99, 100) 100 (100, 100) 100 (99, 100) 100 (100, 100)
11.2 ± 1.7 10.6 ± 4.0 12.9 ± 3.9 10.0 ± 3.7 13 (11, 14)
36.2 30.7 31.2 33.7 36.8
76.3 ± 14.3
98 (97, 99)
17.1 ± 4.3
a
± ± ± ± ±
8.3 9.8 8.5 6.4 6.7
Data were represented as Mean ± Standard Deviation for variables with normal distribution or median (1st quartile, 2nd quartile) for variables with non-normal distribution. a No measurement or numerical value was obtained containing EtCO2, as no patient remained intubated during their recovery (in PACU) and study period.
Capnographic monitoring of ventilation revealed consistent endtidal CO2 pressures throughout the time in which the airway was being secured; EtCO2 (mmHg) at preoxygenation (36.2 ± 8.3), preinduction (30.7 ± 9.8), pre-ETT insertion (31.2 ± 8.5), during laryngoscopy (33.7 ± 6.4), post-ETT insertion (36.8 ± 6.7), correlated expectedly with the induction of anesthesia, the apneic period, and the initiation of mechanical ventilation. The adequacy of the SuperNO2VA™ mask's ability to ventilate and oxygenate patients was verified through additional, measurable factors, such as the lowest SpO2 during the entire airway procedure, peak airway pressures, and tidal volumes. The average for the lowest SpO2 during the entire airway procedure was 98.1 ± 7.0%. And the average peak airway pressure, for all 29 patients, was 17.97 ± 3.95 mmHg with a mean tidal volume of 573.7 ± 40.7 mL (Table 3). 3.3. Safety reporting There were no AEs, SAEs, NSAEs, or UADEs associated with the use of the SuperNO2VA™ mask during the study period. Also, there were no issues reported with mask irritation, mask discomfort, or mask displacement during the study period. 4. Discussion Preliminary findings with the SuperNO2VA™ mask suggest that it is a viable ventilatory device for patients that undergo routine, elective surgical procedures requiring general anesthesia. The SuperNO2VA™ mask's intended use and method of oxygen delivery is very similar to other ventilation devices, such as nasal continuous positive airway pressure (CPAP) or HFNC, by allowing continuous airflow and positive airway pressure to drive oxygen into the airway (from the nasopharynx), actively inflate the lungs to allow for CO2 removal (creating a vacuum effect), and relieve upper airway obstruction with a positive airway pressure near 20 cm H2O or higher (pneumatic stent). For that reason, the SuperNO2VA™ mask may be a practical alternative for patients suffering from, or with the intent to prevent, respiratory depression such as, compression atelectasis and/or oxygen desaturation. Table 3 Summary statistics regarding adequate ventilation and oxygenation with the SuperNO2VA™ mask for the 29 successfully ventilated patients during the airway procedure. Ventilation and Oxygenation with the SuperNO2VA™ Minimal SpO2 During Airway Procedure (%), mean ± SD Peak Airway Pressure (cmH2O), mean ± SD Tidal Volume (mL/kg), mean ± SD
98.1 ± 7.0 17.97 ± 3.95 573.7 ± 40.7
The Nasal Oxygenation and Ventilation of the Airway (NOVA) technique, as described by Cataldo S., et al., demonstrates how continuous positive pressure ventilation during the intubation procedure might eliminate the apneic period and improve patient outcomes by creating a patent airway permitting alveolar ventilation [15]. Also, recent evidence suggests that nasal mask ventilation may be superior to, or as effective as, full facemask ventilation, with lower peak airway pressures and higher flow rates when patients are fully anesthetized [16,17]. A nasal mask permits a seal around the nose with less force and manipulation of the osseous structures of the face than a full facemask. Leakage through the mouth is eliminated with a modified grip that applies pressure onto the mask, permitting the fingers to seal the lips and push the submental space and tongue into the oral cavity. With only the nasal chamber being pressurized, pressure builds up in the nasopharynx stenting the soft palate and tongue from the retropharyngeal wall. During full facemask ventilation, both nasal and oral cavities are pressurized, pushing the tongue back into the soft palate and into the retropharyngeal wall, worsening the upper airway obstruction; likely resulting with the insertion of an airway adjunct (oral airway). Anesthesia practitioners are also required to manipulate the mandible with the “E-C” clamp technique; therefore lifting the face into the mask, where it may become difficult to create an adequate seal for ventilation, as pressure in the oropharynx builds and releases along the path of least resistance, specifically the soft tissue of the cheeks. Additionally, when it is time to perform laryngoscopy, the full facemask is removed, eliminating any oxygenation or ventilation during the apneic period. Conversely, during nasal ventilation, the nasal mask does not need to be removed, as the view into the oral cavity is unobstructed. While oxygen may leak out of the mouth when the mouth is open, most oxygen will continue to flow into the lungs; due to fluid dynamics, a proportional relation to gas flow and diameter allows for the path of least resistance to not be an “all or none” phenomenon [18]. Although the SuperNO2VA™ mask requires a modified grip technique for sufficient oxygen administration and ventilation, the majority of the anesthesia practitioners were satisfied with its use, and provided positive feedback about the SuperNO2VA™’s size and feel. It was noted that minimal effort was required to create a seal around the nose, with either their thumb or the palm of their hand. Different from the standard facemask's finger position, the SuperNO2VA™ allows the fingers to gently apply pressure to the submental space, pushing the tongue into the oral cavity, closing it off to oral leakage and allowing pressure to build up in the retropharynx. The Velcro head strap was referred to as being “clutch”, as it allowed for hands-free oxygenation on several occasions where the provider needed the use of both of their hands. Also, many patients commented on the comfort of the mask, how they felt less
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claustrophobic, and liked that they could communicate easier with their anesthesia practitioner prior to induction. The SuperNO2VA™ mask is a nasal ventilation device that utilizes the clinical benefits of both nasal CPAP and nasal ventilation to address the respiratory compromise induced by intravenous deep sedation and general anesthesia. When a patient receives either intravenous deep sedation or general anesthesia, there is a loss of airway patency and creation of obstruction to flow. Airway collapse and shallow breathing from central nervous system depression will lead to hypoxemia, hypercapnia, atelectasis, respiratory insufficiency, arrest and failure without positive pressure support. Even though the standard full facemasks and nonrebreather masks can provide high FiO2 levels to spontaneously breathing patients [1], the SuperNO2VA™ mask is able to deliver higher FiO2 levels, along with lower peak airway pressures, higher tidal volumes, and continuous, uninterrupted oxygenation and ventilation post induction and throughout the process of securing the airway. Bagvalve-mask devices do not provide oxygen to apneic patients unless manual ventilation is performed; thus, providing minimal oxygenation to these patients, specifically [15]. The use of non-invasive positive pressure ventilation is not limited to the operating room and surgical setting per se; noninvasive positive pressure ventilation has various use and benefits in both intensive care units (ICUs) and emergency departments (EDs), respectfully [1,11,15,16,18]. For patients that cannot reach an acceptable oxygen saturation level with high FiO2 alone, the use of such airway devices like the SuperNO2VA™ mask, during those situations may provide support and relief whenever preoxygenation or tracheal intubation is required outside of an OR [1]. Weingart and Levitan suggest that if patients need CPAP during their preoxygenation period, it may beneficial for them to have the device left on until the moment of tracheal intubation [1]. In contrast, the SuperNO2VA™ mask can be worn during laryngoscopy and tracheal intubation via mechanical/circuit noninvasive positive-pressure ventilation, while prolonging the apneic period and patient desaturation. The recommendation of such noninvasive positive-pressure devices, such as CPAP masks, noninvasive positive-pressure ventilation, or PEEP valves on a bag-valve-mask device should be considered for preoxygenation and ventilation during the onset phase of muscle relaxation in patients who cannot achieve oxygen saturation >93%e95% with high FiO2 [1]. While a nasopharyngeal airway can relieve an upper airway obstruction and a high flow nasal cannula allows for “apneic” oxygenation of the lungs, these devices may lack the ability to apply continuous positive pressure > 7 cm H2O to prevent or treat the complications of atelectasis [3]. As in the treatment of patients with obstructive sleep apnea (OSA), or those receiving high FiO2 and are unable to achieve an oxygen saturation > 90%, continuous positive airway pressure is an effective method to stent open a non-patent airway and ventilate the lungs to prevent and/or treat alveolar collapse. Inside the OR, the SuperNO2VA™ mask attaches to the anesthesia circuit and assists the provider in providing a continuous flow of oxygen to the patient. Outside of the OR, where the anesthetic machine is not available, the nasal mask can connect to a supplemental oxygen source, a mechanical ventilator, or a resuscitator hyperinflation bag for certain procedures where the healthcare provider needs access to the patient's mouth (e.g. EGD/ TEE; colonoscopy, bronchoscopy, flexible scope intubation, laryngoscopy, MRI). Different from the standard OR facemasks that are most often discarded, the SuperNO2VA™ remains with the patient to serve as a rescue device, to provide supplemental oxygenation and apply positive pressure ventilation during laryngoscopy and tracheal intubation, patient transportation, and even if respiratory compromise occurs in the PACU.
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5. Conclusion This observational study demonstrated that the SuperNO2VA™ nasal mask is a safe and tolerable device that facilitates noninvasive positive pressure ventilation, while providing oxygenation while the patient's airway is being secured. Hemodynamically stable vital signs, satisfactory peripheral oxygen saturations, and adequate end-tidal carbon dioxide pressures validate the feasibility of nasal mask ventilation after the induction of anesthesia in the OR. However, considering the novelty of this particular study, further research is warranted to determine its usefulness in patients with known/predicted difficult airways, patients with a history or anticipation of difficult mask ventilation (DMV), or even in patients that have been categorized as ‘high risk’ such as the obese, pregnant, and other populations with poor pulmonary reserve (i.e. OSA, COPD, asthma, cancer). Given that these patients are also at an increased risk for difficult airway management, such as difficult mask ventilation or difficult intubation, they are also at risk for airway management complications, specifically hypoxemia, during the apneic period. Nasal ventilation has not been studied to determine if it increases the risk of gastric insufflation and aspiration. Theoretically, this is less likely to occur with nasal ventilation, as it results in lower peak airway pressures, with the mouth acting anecdotally as its own pressure relief valve. Additionally, this study did not determine the mask's effectiveness during a prolonged apneic period, as all patients were successfully intubated on the 1st attempt and within 2.5 min. Thus, further exploration and research is warranted with this device in these clinical circumstances. Disclosures (conflict of interest) Dr. Hagberg has a financial relationship with Ambu (Project number 5109), Cadence Pharmaceuticals (Project number 8990), Karl Storz Endoscopy (Project number 9394), and MedCom (Project number 10857) Flow in the form of funded research and is an unpaid consultant for Ambu, Covidien and SonarMed. Funding source This work was supported by Revolutionary Medical Devices, Inc. (Covidien-Medtronic) (Project number 11357), in conjunction with Covidien-Medtronic (Project number 11023). Acknowledgements Dr. Cai's research was supported by the National Institutes of Health's Clinical and Translational Science Award grant (UL1 TR000371), awarded to the University of Texas Health Science Center at Houston in 2012 by the National Center for Clinical and Translational Sciences. Appendix Abbreviations AA AE ADE ASA BMI BP CPAP CRF CO2
Anesthetist Assistant Adverse Event Adverse Device Effect American Society of Anesthesiology Body Mass Index Blood Pressure Continuous Positive Airway Pressure Case Report Form Carbon Dioxide
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DMV ECG ETCO2 ETT FRC HIPAA IRB OSA PACU PD PHI SpO2
Difficult Mask Ventilation Electrocardiogram End-tidal Carbon Dioxide Endotracheal Tube Functional Residual Capacity Health Insurance Portability and Accountability Act Institutional Review Board Obstructive Sleep Apnea Post Anesthesia Care Unit Protocol Deviation Protected Health Information Blood Oxygen Saturation
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Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study Semhar Ghebremichael a, Sam D. Gumbert a, Naveen Vanga a, Omar L. Mancillas a, Tyrone Burnett Jr. a, Chunyan Cai b, Carin A. Hagberg a, * a
Department of Anesthesiology, The University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School, 6431 Fannin St., MSB 5.020, Houston, TX, 77030, USA Department of Internal Medicine, The University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School, 6410 Fannin St., UPB 1100.08, Houston, TX, 77030, USA
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 27 June 2017 Received in revised form 16 September 2017 Accepted 28 September 2017
Background: One of the biggest challenges for anesthesia practitioners during airway management is the maintenance of adequate oxygenation and ventilation during difficult and emergency airway situations. Providing nasal ventilation during the “apneic period”, defined as the time between the end of bag-mask ventilation and successful placement of an appropriate airway device, may allow for improved oxygenation throughout the process in which the airway is secured. The SuperNO2VA™ mask (Revolutionary Medical Devices, USA) is a newly developed nasal mask that delivers non-invasive positive pressure nasal ventilation that is designed to provide continuous oxygenation and ventilation during anesthetic induction until the airway is secured. Aim: The purpose of this study was to evaluate the clinical performance of the SuperNO2VA™ mask for nasal oxygenation and ventilation during pre-induction, post-induction, laryngoscopy, and tracheal intubation in adult patients requiring general anesthesia. Methods: Following IRB/ethical board approval and written informed consent, 30 adult patients, ages 18 years or older, with an ASA status I-III, who were scheduled for an elective surgery that required general anesthesia and tracheal intubation, were enrolled into this study. Patient demographic characteristics and intervening outcomes were all recorded. The SuperNO2VA™’s efficacy was evaluated by the measurement and recorded values of peak airway pressures, tidal volumes, minimal oxygen saturation values (while the airway was secured), as well as, an objective assessment grading scale for mask ventilation. The time required to secure the airway, including laryngoscopy, was also recorded. Results: The SuperNO2VA™ nasal mask provided adequate oxygenation and successful ventilation in 29 of 30 patients, resulting in an overall success rate of 97% (95% confidence interval: 83%e100%). One patient was unable to be successfully ventilated by the SuperNOVA™ mask and was noted a Grade IV. The mean duration of laryngoscopy was 50.7 ± 23.2 s, with an average SpO2 of 99.6 ± 0.8% calculated for this interval. The lowest observed SpO2 for the 29 patients at preoxygenation, pre-induction, pre-ETT insertion, during laryngoscopy, post-intubation, and in the PACU was 95, 97, 97, 97, 98, and 94%, respectively. The average for the lowest SpO2 during the entire airway procedure was 98.1 ± 7.0%. And the average peak airway pressure, for all 29 patients, was 17.97 ± 3.95 mmHg, with a mean tidal volume of 573.7 ± 40.7 mL. Conclusion: This observational study demonstrated that the SuperNO2VA™ mask facilitates non-invasive positive pressure ventilation while providing adequate oxygenation and ventilation during preinduction, post-induction, laryngoscopy, and tracheal intubation in elective surgical patients. Conversely, considering the novelty of this particular study, further research is warranted to determine its usefulness in patients with known/predicted difficult airways, or even during emergent situations. Published by Elsevier Ltd.
Keywords: Airway management Apneic oxygenation Nasal ventilation Non-invasive positive pressure ventilation Safe apneic period Supplemental oxygen
* Corresponding author. Present Address: The University of Texas MD Anderson Cancer Center, Division of Anesthesiology, Critical Care & Pain Medicine, 1400 Holcombe Blvd., Unit 409, Houston, TX 77030, USA. E-mail addresses: [email protected] (S. Ghebremichael), [email protected] (S.D. Gumbert), [email protected] (N. Vanga), [email protected] (O.L. Mancillas), [email protected] (T. Burnett), [email protected] (C. Cai), [email protected] (C.A. Hagberg). https://doi.org/10.1016/j.tacc.2017.09.054 2210-8440/Published by Elsevier Ltd.
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1. Introduction
2. Materials and methods
One of the biggest challenges for anesthesia practitioners during airway management is the maintenance of adequate oxygenation and ventilation when a difficult airway is encountered. Previous studies have investigated several options/techniques that may help prolong, and possibly prevent, desaturation; however, these specific techniques do not eliminate the critical apneic period, altogether [1e3]. The Difficult Airway Society (DAS) created guidelines for managing difficult airways with several techniques and tips to optimize oxygenation and ventilation prior to intubation, but there is no mention of ventilation during the period of laryngoscopy and tracheal intubation in the most recent American Society of Anesthesiologist's (ASA's) guidelines [4]. Intravenous (IV) deep sedation and the induction of general anesthesia cause respiratory compromise by fundamentally affecting the chemical, neurological, and mechanical regulation of ventilation. It is this sequence of events that induces upper airway obstruction and respiratory depression that may subsequently cause hypoventilation, atelectasis, and ultimately oxygen desaturation leading to hypoxemia [2e6]. Certain patient populations (i.e. pediatric, obese, and obstetric) are considered ‘at (high) risk’ for rapid desaturation after the induction of general anesthesia. Causes are due to increased oxygen consumption, reduced functional residual capacity (FRC), and/or poor oxygen reserve that hasten the development of hypoxemia [1e6]. In current clinical practice, it is common that pre-oxygenation is performed with 100% FiO2 for approximately 3 min, and patients are instructed to breathe deeply to help establish a safe apneic period [1]. Extending the safe apneic period, or the time between the onset of apnea until end-tidal oxygen (EtO2) percentage reaches 90% or less, increases the patient's margin of safety [1,4]. Further maneuvers are indicated in high-risk patients for optimal preoxygenation. Positive pressure ventilation and 25 ramped up positioning are recommended for obese patients [7] and may be useful in all patients. ICU patients have maximal benefit from noninvasive ventilation (NIV) [8,9], when coupled with high flow nasal cannula (HFNC) [10], while extension of safe apnea time can be granted with apneic oxygenation techniques, such as nasal oxygen during efforts securing a tube (NODESAT, usually with a nasal cannula) [1,11] or HFNC [12]. The SuperNO2VA™ (Revolutionary Medical Devices, Inc., Tucson, AZ, USA) is a newly developed nasal mask that delivers noninvasive positive pressure ventilation through the nasal route to provide continuous oxygenation and ventilation during anesthetic induction and throughout laryngoscopy. The SuperNO2VA™ mask was designed to create a seal, deliver gas, and generate positive pressure, allowing for continuous nasal oxygenation and ventilation during sedation, by placement over the patient's nose and connection to a gas source, so that positive pressure builds up inside the mask (Fig. 1). This pressure, therefore, helps separate the soft palate from the posterior pharygeal wall and forces oxygen to flow from the nose to the lungs. The purpose of this study was to determine the clinical performance of SuperNO2VA™ technology post induction, as measured by the average lowest oxygen saturation (SpO2), peak airway pressures and tidal volumes, average end-tidal of carbon dioxide (EtCO2), and average objective ventilation scale grades, as previously described by Han R., et al. [13]. SuperNO2VA™ safety and tolerability were secondary objectives that consisted of technical performance, indicated by the incidence and nature of adverse events (AEs), serious adverse events (SAEs), unanticipated adverse device effects (UADEs) and their duration, resolution and required treatment, if any, along with the time required to secure the airway during laryngoscopy.
After approval of the protocol by the Institutional Review Board (IRB) of the University of Texas Health Science Center at Houston (UTHealth) McGovern Medical School and the Research Committee of the Department of Anesthesiology, 30 adult patients scheduled for elective surgery at Memorial Hermann HospitaleTexas Medical Center were recruited to participate in this non-randomized, observational, prospective study. Key research personnel, such as the principal investigator, co-investigator, and/or study coordinators, obtained informed consent preoperatively. Each eligible patient was provided with a detailed explanation of the study's purpose and their role as a participant by both oral and written communications. All protected health information (PHI) was secured in an encrypted database in accordance with the Health Insurance Portability Accountability Act of 1996 (HIPAA). The study period consisted of 3 months from February through April 2016. 2.1. Patient selection The study's cohort was comprised of individuals scheduled to undergo surgery that met the following inclusion criteria: (1) age of 18 years old or older, and (2) American Society of Anesthesiology (ASA) physical status I-III. Exclusion criteria consisted of the following: (1) any presence of an underlying neuromuscular disease, (2) use of medications known to interfere with neuromuscular transmission, (3) history of cervical spine injury or cervical pathology, (4) presence of renal or hepatic disease, and (5) inability to fit the mask. Morphometric characteristics, such as neck circumference, inter-incisor gap, thyromental distance, and sternomental distance were measured and recorded for all patients. The quality of each patient's airway was evaluated using the physical examination recommendations in the most recent American Society of Anesthesiologist's (ASA) “Practice Guidelines for Management of the Difficult Airway” [14]. Also, a review of previous airway management history was obtained, including, history of snoring, diagnosis of obstructive sleep apnea (OSA), anticipated difficult-mask-ventilation (DMV), laryngoscopy, or intubation, as well as, any history of DMV, difficult laryngoscopy or intubation, presence of facial hair, body mass index (BMI) > 30 kg/m2, elderly (>55 years old), and/or edentulous. 2.2. Study procedure Each patient received general anesthesia and was intubated by either direct or video laryngoscopy. In the operating room (OR), standard monitoring devices were applied, including a pulse oximeter, 3-lead electrocardiogram, and blood pressure monitoring (in which the latter may be invasive or non-invasive). Measures of blood pressure, heart rate, respiratory rate, SpO2, and EtCO2 were observed and recorded before the patient's surgical preparation, and periodically while the airway was being secured. Vital signs were recorded immediately before oxygen administration, before induction of anesthesia, before ETT insertion, during laryngoscopy, after ETT insertion, and postoperatively during the participant's recovery in the post-anesthesia care unit (PACU). Study providers included attending anesthesiologists, resident anesthesiologists, anesthesiologist assistants, and an anesthesiologist assistant student. The SuperNO2VA™ mask is intended to facilitate simultaneous oxygenation and ventilation through the nose, allowing the clinician to have an unobstructed view of the airway during laryngoscopy, intubation, and/or procedures requiring access to the oral cavity (Fig. 2). Only an “Adult Large” size of the SuperNO2VA™ mask was used during the study period. This was largely due to the
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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3
Fig. 1. The SuperNO2VA™ mask.
manufacture's limited development of other various sizes during the trial (SuperNO2VA™ mask sizing is based on height, not weight; an “Adult Large” recommended height range is 180e220 cm). Study personnel prepared and assembled the SuperNO2VA™ mask before each patient entered the OR. The original, standard, facemask was removed from the mechanical ventilator, via anesthesia circuit, and was replaced with the SuperNO2VA™ mask for oxygen administration. The end-tidal CO2 monitor and tubing were attached to the SuperNO2VA™ mask to ensure whether or not the subject was being ventilated prior to laryngoscopy. Once the SuperNO2VA™ mask was securely assembled, the anesthesia practitioner was able to provide oxygen and/or ventilation the patient prior to induction, during induction, post induction, laryngoscopy, and intubation. Before anesthesia induction, the SuperNO2VA™ mask was placed and secured onto the patient's nose, utilizing its prepackaged Velcro straps, and was assessed for comfort ability and tolerability through verbal communication and subjective assessment. General anesthesia was then induced by intravenous administration of propofol (1.5e2 mg/kg) and fentanyl (1 mcg/kg) and maintained with an inhalation agent. Rocuronium (0.6 mg/kg) was administered to induce muscle relaxation. The lungs were mechanically ventilated with a semi-closed circle system to maintain an end-tidal CO2 near 35 mmHg. Ventilation was maintained via SuperNO2VA™ mask with 100% oxygen administration, until the patient was completely relaxed (0 on train of four on twitch monitor). The anesthesia practitioner then attempted to ventilate the patient with the SuperNO2VA™ mask. If the anesthesia practitioner was able to ventilate the patient based on the following observations/indications: fogging of the SuperNO2VA™ mask, chest rise
and fall of the patient, measured EtCO2 waveform capnography, and/or lung auscultation, then the patient was placed on pressurecontrolled ventilation at a pressure of 20 mm H2O, PEEP of 10 cm H2O, with a respiratory rate of 12 breaths per minute (suggested manufacturer settings), and a FiO2 flow setting of 30 L/min with 100% oxygen. If the anesthesia practitioner could not ventilate the patient with the SuperNO2VA™ mask, the device was deemed a failure and the patient was ventilated with the standard facemask instead. With the SuperNO2VA™ mask appropriately secured to the patient and allowing adequate mechanical ventilation, the anesthesia practitioner then attempted to perform laryngoscopy and tracheal intubation with the SuperNO2VA™ attached to the patient. During the entire airway procedure, research personnel recorded the lowest SpO2 during the airway procedure, peak airway pressures, and tidal volumes while the SuperNO2VA™ was used. After the airway was secured, the anesthesia practitioner discontinued their use of the SuperNO2VA™ mask, which concluded the research intervention. As a result, a classification grade was then reported by the study anesthesiologist, signifying the SuperNO2VA™’s ability to mask ventilate (Fig. 3) [13]. For study purposes, adverse events were categorized into 2 groups: (1) Serious Adverse Events (SAE), and/or (2) Non-Serious Adverse Events (NSAEs). The causal relationship of each AE was assessed by the Principal Investigator (PI) as either, related to the device (including its deployment), or not related to the device (including its deployment). Furthermore, each AE that was classified as being related to the device (including its deployment), would then be determined as being either anticipated or unanticipated, by the PI. Recognized risks associated with the use of the SuperNO2VA™ mask included, but was not limited to, the
Fig. 2. Three plausible applications of the SuperNO2VA™ mask for its intended use; (left) during laryngoscopy, (middle) during a rescue setting with the assistance of fiberoptics, and (right) nasal ventilation.
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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S. Ghebremichael et al. / Trends in Anaesthesia and Critical Care xxx (2017) 1e8
Fig. 3. Han et al. [12] classification scale used for assessing the SuperNO2VA™ mask Ease of Use.
following: (1) allergic reactions, (2) skin abrasions, (3) pressure ulcers, and/or (4) ocular injury. Patient safety was defined by the incidence and nature of AEs, SAEs, NSAEs, or UADEs and their duration; this also included their respective resolutions and required treatments, as a result from the utilization of the SuperNO2VA™ mask during the interventional study period. Patient tolerability was defined as complete removal and discontinued use of the SuperNO2VA™ mask due to any of the following physical observations, including mask irritation, mask discomfort, and/or mask displacement. 2.3. Statistical methods Data was summarized as mean ± standard deviation (mean ± SD) for continuous variables with normal distribution and median (interquartile range) with non-normal distribution, along with frequency and percentage for categorical variables. The percentage of successful ventilation, as well as its 95% confidence interval, was calculated. All analyses were performed using SAS 9.4 (Cary, NC). We enrolled 30 human subjects into this study. Using binomial staged sampling, this sample size is expected to identify ventilation failures (1 or fewer cases) with a 0.95 confidence limit and a 0.25 upper confidence level.
3.1. Patient demographics and characteristics Table 1 summarizes patient demographics and other clinical variables for all 30 patients, in accordance with their respective ventilation grade. Analysis of the demographics for the 30 patients revealed a heterogeneous population of 19 males and 11 females, aged 46.3 ± 17.2 years, with 10 patients >55 years of age. Of the elderly patients, only one was edentulous. Of the males that were successfully ventilated, only 3 were considered “clean shaven”, the rest presented with stubble, goatee, mustache, and/or beard. Of the patients with a pertinent past medical history, 11 presented with a history of snoring, 7 with OSA, 4 with anticipated DMV, and none with a history of DMV, laryngoscopy, or intubation. Eighteen patients presented with a BMI >30 kg/m2, with a mean BMI of 34.1 ± 9.9 kg/m2. All patients ranged with Mallampati classifications I-III; Mallampati I (14), Mallampati II (11), and Mallampati III (5). Morphometric characteristics included the following difficult airway predictors for tracheal intubation: neck circumferences >41 cm (female) and >43 cm (male), inter-incisor gap distances <4 cm, thyromental distances <6 cm, and sternomental distances <12 cm. Only 2 males and 2 females presented with 2 predictors, while all the other patients had either one or none of the suggested difficult airway predictors. 3.2. Oxygenation and ventilation with the SuperNO2VA™
3. Results Pulmonary ventilation by the SuperNO2VA™ mask was successful in 29 of the 30 patients (97%) during the securement of their airways. Six patients with a ventilation Grade II required placement of a nasal airway adjuvant (i.e. nasal trumpet) to facilitate adequate nasal mask ventilation. One patient received a ventilation grade of III since 2 providers were required to achieve successful ventilation. The anesthesiologist experienced difficulty creating a seal at the lips after the administration of muscle relaxant, necessitating 2 hands to manipulate the SuperNO2VA™ mask, along with the patient's mouth, while the other provider squeezed the oxygen reservoir bag for manual ventilation. A ventilation Grade IV was obtained in 1 patient due to the inability to provide adequate and effective nasal mask ventilation. After intravenous induction, the attending anesthesiologist determined that he was not able to mask ventilate by the absence of EtCO2, no mask condensation, in addition to no chest movement. Although this patient did not experience any oxygen desaturation during the interventional period, the provider switched to the standard full-face mask for ventilation before allowing additional attempts to ventilate with the SuperNO2VA™ mask. This particular case was deemed a failure and was only included in the analysis of patient demographics, as no values related to its clinical performance were recorded. This particular failure may have been attributed to user error, as the mask does require a modified grip when creating a sufficient seal on the patient's nose and mouth for effective positive pressure nasal ventilation. Although Cormack-Lehane (C-L) classification was not recorded as a pertinent data point, there were no difficult intubations during the study period.
Twenty-eight patients were assessed with either a ventilation Grade I or II (93.3%), and only one patient was assessed as a Grade III, requiring additional assistance. One patient received a Grade IV for unsuccessful nasal ventilation and was deemed a failure. The SuperNO2VA™ nasal mask provided satisfactory oxygenation and ventilation in 29 of 30 patients, resulting in an overall success rate of 97% (95% confidence interval: 83%e100%). Collectively, 22 patients (73.3%) were assessed with a ventilation Grade I, 6 patients (20%) were assessed with a ventilation Grade II, 1 patient (3.3%) was assessed with a ventilation Grade III, and 1 patient (3.3%) was assessed with a ventilation Grade IV. Also, 20 patients (66.7%) were intubated via direct laryngoscopy versus 10 patients (33.3%) that were intubated via indirect (video) laryngoscopy. Table 2 summarizes the vital signs for the 29 patients with ventilation Grades I-III. Systolic (110.2 ± 22.0 mmHg) and diastolic (68.0 ± 15.8 mmHg) blood pressures remained stable throughout the study and trended accordingly with the onset, maintenance and discontinuation of general anesthesia. Heart rates for the 29 patients throughout the study remained stable with an average of 76.8 ± 15.0 beats per minute during laryngoscopy. Respiratory rates for all included patients also remained stable with an average of 10.0 ± 3.7 breaths per minute. The 29 patients successfully ventilated by SuperNO2VA™ nasal mask were all intubated on the first attempt. The mean duration of laryngoscopy was 50.7 ± 23.2 s, with an average SpO2 of 99.6 ± 0.8% calculated for this interval. The lowest observed SpO2 for the 29 patients at preoxygenation, pre-induction, pre-ETT insertion, during laryngoscopy, post-intubation, and in the PACU was 95, 97, 97, 97, 98, and 94%, respectively. Oxygen saturation <92% did not occur.
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
S. Ghebremichael et al. / Trends in Anaesthesia and Critical Care xxx (2017) 1e8
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Table 1 Summary statistics of demographics, baseline morphometric characteristics, and anesthetist levels in all 30 patients (in both Table's 1a and 1b). a. Summary of demographics, morphometric characteristics, and anesthetist levels.
Age (in years), mean ± SD Gender, no. (%) Female Male Body Mass Index (BMI) (kg/m2), mean ± SD Height (cm), mean ± SD Weight (kg), mean ± SD Inter-incisor gap distance (cm), mean ± SD Neck circumference (cm), mean ± SD Thyromental distance (cm), mean ± SD Sternomental distance (cm), mean ± SD Mallampati Class., no. (%) 1 2 3 Anesthetist level, no. (%) Attending anesthesiologist CA-1 CA-2 CA-3 Anesthesiologist assistant (AA) AA student
Total (n ¼ 30)
Ventilation Grade I (n ¼ 22)
Ventilation Grade II (n ¼ 6)
Ventilation Grade III (n ¼ 1)
Ventilation Grade IV (n ¼ 1)
46.3 ± 17.2
41.4 ± 16.7
62.2 ± 7.6
64
43
11 (36.7) 19 (63.3) 34.1 ± 9.9 168.6 ± 11.4 97.7 ± 31.2 4.3 ± 0.7 42.9 ± 5.9 7.9 ± 1.3 14.2 ± 1.9
9 (40.9) 13 (59.1) 33.0 ± 9.7 169.5 ± 12.6 95.7 ± 32.6 4.2 ± 0.6 41.7 ± 5.3 7.9 ± 1.1 14.4 ± 2.0
2 (33.3) 4 (66.7) 35.4 ± 9.1 166.4 ± 5.3 98.9 ± 30.6 4.7 ± 1.1 46.1 ± 7.3 7.3 ± 2.1 13.0 ± 1.9
0 (0.0) 1 (100.0) 31.6 177.8 100 5 43.5 9.5 15
0 (0.0) 1 (100.0) 54.9 154.9 131.82 4.5 50.5 9.5 15
14 (46.7) 11 (36.7) 5 (16.6)
9 (40.9) 9 (40.9) 4 (18.2)
3 (50.0) 2 (33.3) 1 (16.7)
1 (100.0) 0 (0.0) 0 (0.0)
1 (100.0) 0 (0.0) 0 (0.0)
2 (6.7) 4 (13.3) 1 (3.3) 3 (10.0) 19 (63.3) 1 (3.3)
1 (4.5) 2 (9.1) 1 (4.5) 2 (9.1) 16 (72.7) 0 (0.0)
0 2 0 1 2 1
0 0 0 0 1 0
1 0 0 0 0 0
(0.0) (33.3) (0.0) (16.7) (33.3) (16.7)
(0.0) (0.0) (0.0) (0.0) (100.0) (0.0)
(100.0) (0.0) (0.0) (0.0) (0.0) (0.0)
b. Summary of demographics and morphometric characteristics (Cont.). Total (n ¼ 30) Elderly ( 55 years old), no. (%) No 20 (66.7) Yes 10 (33.3) 2 BMI > 30 (kg/m ), no. (%) No 12 (40.0) Yes 18 (60.0) Edentulous, no. (%) No 29 (96.7) Yes 1 (3.3) History of snoring, no. (%) No 19 (63.3) Yes 11 (36.7) Diagnosis of obstructive sleep apnea (OSA), no. (%) No 23 (76.6) Yes 7 (23.3) Anticipated difficult mask ventilation (DMV), no. (%) No 26 (86.6) Yes 4 (13.3) History of DMV, no. (%) No 30 (100.0) Yes 0 (0.0) Beard, no. (%) No 25 (83.3) Yes 5 (16.7) Stubble, no. (%) No 27 (90.0) Yes 3 (10.0) Mustache, no. (%) No 18 (60.0) Yes 12 (40.0) Goatee, no. (%) No 8 (93.3) Yes 2 (6.7) Shaven, no. (%) No 27 (90.0) Yes 3 (10.0) Upper-lip-bite-test (ULBT), no. (%) 1 15 (50.0) 2 7 (23.3) 3 8 (26.7)
Ventilation Grade I (n ¼ 22)
Ventilation Grade II (n ¼ 6)
Ventilation Grade III (n ¼ 1)
Ventilation Grade IV (n ¼ 1)
17 (77.3) 5 (22.7)
2 (33.3) 4 (66.7)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
10 (45.5) 12 (54.5)
2 (33.3) 4 (66.7)
0 (0.0) 1 (100.0)
0 (0.0) 1 (100.0)
22 (100.0) 0 (0.0)
5 (83.3) 1 (16.7)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
14 (63.6) 8 (36.4)
4 (66.7) 2 (33.3)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
16 (72.7) 6 (27.3)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
21 (95.5) 1 (4.5)
4 (66.7) 2 (33.3)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
22 (100.0) 0 (0.0)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
18 (81.8) 4 (18.2)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
20 (90.9) 2 (9.1)
5 (83.3) 1 (16.7)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
14 (63.6) 8 (36.4)
3 (50.0) 3 (50.0)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
21 (95.5) 1 (4.5)
6 (100.0) 0 (0.0)
0 (0.0) 1 (100.0)
1 (100.0) 0 (0.0)
19 (86.4) 3 (13.6)
6 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
1 (100.0) 0 (0.0)
9 (40.9) 7 (31.8) 6 (27.3)
4 (66.7) 0 (0.0) 2 (33.3)
1 (100.0) 0 (0.0) 0 (0.0)
1 (100.0) 0 (0.0) 0 (0.0)
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Table 2 Summary statistics of vital signs for the 29 successfully ventilated patients. Systolic Blood Pressure (mmHg)
Pre-oxygenation Pre-induction Pre-ETT Insertion During Laryngoscopy Post-ETT Insertion Postoperative (PACU)
141.2 138.5 125.9 110.2 113.8
± ± ± ± ±
12.5 16.2 21.2 22.0 24.7
135.1 ± 19.4
Diastolic Blood Pressure (mmHg) 83.9 81.3 74.6 68.0 73.4
± ± ± ± ±
13.0 12.1 13.4 15.8 20.3
76.7 ± 9.5
Heart Rate (Beats/min.)
SpO2 (%)
Respiratory Rate (Breaths/min.)
EtCO2 (mmHg)
75.1 ± 11.0 72 (65, 83) 75.5 ± 13.9 76.8 ± 15.0 88.3 ± 18.2
99 (96, 100) 100 (99, 100) 100 (100, 100) 100 (99, 100) 100 (100, 100)
11.2 ± 1.7 10.6 ± 4.0 12.9 ± 3.9 10.0 ± 3.7 13 (11, 14)
36.2 30.7 31.2 33.7 36.8
76.3 ± 14.3
98 (97, 99)
17.1 ± 4.3
a
± ± ± ± ±
8.3 9.8 8.5 6.4 6.7
Data were represented as Mean ± Standard Deviation for variables with normal distribution or median (1st quartile, 2nd quartile) for variables with non-normal distribution. a No measurement or numerical value was obtained containing EtCO2, as no patient remained intubated during their recovery (in PACU) and study period.
Capnographic monitoring of ventilation revealed consistent endtidal CO2 pressures throughout the time in which the airway was being secured; EtCO2 (mmHg) at preoxygenation (36.2 ± 8.3), preinduction (30.7 ± 9.8), pre-ETT insertion (31.2 ± 8.5), during laryngoscopy (33.7 ± 6.4), post-ETT insertion (36.8 ± 6.7), correlated expectedly with the induction of anesthesia, the apneic period, and the initiation of mechanical ventilation. The adequacy of the SuperNO2VA™ mask's ability to ventilate and oxygenate patients was verified through additional, measurable factors, such as the lowest SpO2 during the entire airway procedure, peak airway pressures, and tidal volumes. The average for the lowest SpO2 during the entire airway procedure was 98.1 ± 7.0%. And the average peak airway pressure, for all 29 patients, was 17.97 ± 3.95 mmHg with a mean tidal volume of 573.7 ± 40.7 mL (Table 3). 3.3. Safety reporting There were no AEs, SAEs, NSAEs, or UADEs associated with the use of the SuperNO2VA™ mask during the study period. Also, there were no issues reported with mask irritation, mask discomfort, or mask displacement during the study period. 4. Discussion Preliminary findings with the SuperNO2VA™ mask suggest that it is a viable ventilatory device for patients that undergo routine, elective surgical procedures requiring general anesthesia. The SuperNO2VA™ mask's intended use and method of oxygen delivery is very similar to other ventilation devices, such as nasal continuous positive airway pressure (CPAP) or HFNC, by allowing continuous airflow and positive airway pressure to drive oxygen into the airway (from the nasopharynx), actively inflate the lungs to allow for CO2 removal (creating a vacuum effect), and relieve upper airway obstruction with a positive airway pressure near 20 cm H2O or higher (pneumatic stent). For that reason, the SuperNO2VA™ mask may be a practical alternative for patients suffering from, or with the intent to prevent, respiratory depression such as, compression atelectasis and/or oxygen desaturation. Table 3 Summary statistics regarding adequate ventilation and oxygenation with the SuperNO2VA™ mask for the 29 successfully ventilated patients during the airway procedure. Ventilation and Oxygenation with the SuperNO2VA™ Minimal SpO2 During Airway Procedure (%), mean ± SD Peak Airway Pressure (cmH2O), mean ± SD Tidal Volume (mL/kg), mean ± SD
98.1 ± 7.0 17.97 ± 3.95 573.7 ± 40.7
The Nasal Oxygenation and Ventilation of the Airway (NOVA) technique, as described by Cataldo S., et al., demonstrates how continuous positive pressure ventilation during the intubation procedure might eliminate the apneic period and improve patient outcomes by creating a patent airway permitting alveolar ventilation [15]. Also, recent evidence suggests that nasal mask ventilation may be superior to, or as effective as, full facemask ventilation, with lower peak airway pressures and higher flow rates when patients are fully anesthetized [16,17]. A nasal mask permits a seal around the nose with less force and manipulation of the osseous structures of the face than a full facemask. Leakage through the mouth is eliminated with a modified grip that applies pressure onto the mask, permitting the fingers to seal the lips and push the submental space and tongue into the oral cavity. With only the nasal chamber being pressurized, pressure builds up in the nasopharynx stenting the soft palate and tongue from the retropharyngeal wall. During full facemask ventilation, both nasal and oral cavities are pressurized, pushing the tongue back into the soft palate and into the retropharyngeal wall, worsening the upper airway obstruction; likely resulting with the insertion of an airway adjunct (oral airway). Anesthesia practitioners are also required to manipulate the mandible with the “E-C” clamp technique; therefore lifting the face into the mask, where it may become difficult to create an adequate seal for ventilation, as pressure in the oropharynx builds and releases along the path of least resistance, specifically the soft tissue of the cheeks. Additionally, when it is time to perform laryngoscopy, the full facemask is removed, eliminating any oxygenation or ventilation during the apneic period. Conversely, during nasal ventilation, the nasal mask does not need to be removed, as the view into the oral cavity is unobstructed. While oxygen may leak out of the mouth when the mouth is open, most oxygen will continue to flow into the lungs; due to fluid dynamics, a proportional relation to gas flow and diameter allows for the path of least resistance to not be an “all or none” phenomenon [18]. Although the SuperNO2VA™ mask requires a modified grip technique for sufficient oxygen administration and ventilation, the majority of the anesthesia practitioners were satisfied with its use, and provided positive feedback about the SuperNO2VA™’s size and feel. It was noted that minimal effort was required to create a seal around the nose, with either their thumb or the palm of their hand. Different from the standard facemask's finger position, the SuperNO2VA™ allows the fingers to gently apply pressure to the submental space, pushing the tongue into the oral cavity, closing it off to oral leakage and allowing pressure to build up in the retropharynx. The Velcro head strap was referred to as being “clutch”, as it allowed for hands-free oxygenation on several occasions where the provider needed the use of both of their hands. Also, many patients commented on the comfort of the mask, how they felt less
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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claustrophobic, and liked that they could communicate easier with their anesthesia practitioner prior to induction. The SuperNO2VA™ mask is a nasal ventilation device that utilizes the clinical benefits of both nasal CPAP and nasal ventilation to address the respiratory compromise induced by intravenous deep sedation and general anesthesia. When a patient receives either intravenous deep sedation or general anesthesia, there is a loss of airway patency and creation of obstruction to flow. Airway collapse and shallow breathing from central nervous system depression will lead to hypoxemia, hypercapnia, atelectasis, respiratory insufficiency, arrest and failure without positive pressure support. Even though the standard full facemasks and nonrebreather masks can provide high FiO2 levels to spontaneously breathing patients [1], the SuperNO2VA™ mask is able to deliver higher FiO2 levels, along with lower peak airway pressures, higher tidal volumes, and continuous, uninterrupted oxygenation and ventilation post induction and throughout the process of securing the airway. Bagvalve-mask devices do not provide oxygen to apneic patients unless manual ventilation is performed; thus, providing minimal oxygenation to these patients, specifically [15]. The use of non-invasive positive pressure ventilation is not limited to the operating room and surgical setting per se; noninvasive positive pressure ventilation has various use and benefits in both intensive care units (ICUs) and emergency departments (EDs), respectfully [1,11,15,16,18]. For patients that cannot reach an acceptable oxygen saturation level with high FiO2 alone, the use of such airway devices like the SuperNO2VA™ mask, during those situations may provide support and relief whenever preoxygenation or tracheal intubation is required outside of an OR [1]. Weingart and Levitan suggest that if patients need CPAP during their preoxygenation period, it may beneficial for them to have the device left on until the moment of tracheal intubation [1]. In contrast, the SuperNO2VA™ mask can be worn during laryngoscopy and tracheal intubation via mechanical/circuit noninvasive positive-pressure ventilation, while prolonging the apneic period and patient desaturation. The recommendation of such noninvasive positive-pressure devices, such as CPAP masks, noninvasive positive-pressure ventilation, or PEEP valves on a bag-valve-mask device should be considered for preoxygenation and ventilation during the onset phase of muscle relaxation in patients who cannot achieve oxygen saturation >93%e95% with high FiO2 [1]. While a nasopharyngeal airway can relieve an upper airway obstruction and a high flow nasal cannula allows for “apneic” oxygenation of the lungs, these devices may lack the ability to apply continuous positive pressure > 7 cm H2O to prevent or treat the complications of atelectasis [3]. As in the treatment of patients with obstructive sleep apnea (OSA), or those receiving high FiO2 and are unable to achieve an oxygen saturation > 90%, continuous positive airway pressure is an effective method to stent open a non-patent airway and ventilate the lungs to prevent and/or treat alveolar collapse. Inside the OR, the SuperNO2VA™ mask attaches to the anesthesia circuit and assists the provider in providing a continuous flow of oxygen to the patient. Outside of the OR, where the anesthetic machine is not available, the nasal mask can connect to a supplemental oxygen source, a mechanical ventilator, or a resuscitator hyperinflation bag for certain procedures where the healthcare provider needs access to the patient's mouth (e.g. EGD/ TEE; colonoscopy, bronchoscopy, flexible scope intubation, laryngoscopy, MRI). Different from the standard OR facemasks that are most often discarded, the SuperNO2VA™ remains with the patient to serve as a rescue device, to provide supplemental oxygenation and apply positive pressure ventilation during laryngoscopy and tracheal intubation, patient transportation, and even if respiratory compromise occurs in the PACU.
7
5. Conclusion This observational study demonstrated that the SuperNO2VA™ nasal mask is a safe and tolerable device that facilitates noninvasive positive pressure ventilation, while providing oxygenation while the patient's airway is being secured. Hemodynamically stable vital signs, satisfactory peripheral oxygen saturations, and adequate end-tidal carbon dioxide pressures validate the feasibility of nasal mask ventilation after the induction of anesthesia in the OR. However, considering the novelty of this particular study, further research is warranted to determine its usefulness in patients with known/predicted difficult airways, patients with a history or anticipation of difficult mask ventilation (DMV), or even in patients that have been categorized as ‘high risk’ such as the obese, pregnant, and other populations with poor pulmonary reserve (i.e. OSA, COPD, asthma, cancer). Given that these patients are also at an increased risk for difficult airway management, such as difficult mask ventilation or difficult intubation, they are also at risk for airway management complications, specifically hypoxemia, during the apneic period. Nasal ventilation has not been studied to determine if it increases the risk of gastric insufflation and aspiration. Theoretically, this is less likely to occur with nasal ventilation, as it results in lower peak airway pressures, with the mouth acting anecdotally as its own pressure relief valve. Additionally, this study did not determine the mask's effectiveness during a prolonged apneic period, as all patients were successfully intubated on the 1st attempt and within 2.5 min. Thus, further exploration and research is warranted with this device in these clinical circumstances. Disclosures (conflict of interest) Dr. Hagberg has a financial relationship with Ambu (Project number 5109), Cadence Pharmaceuticals (Project number 8990), Karl Storz Endoscopy (Project number 9394), and MedCom (Project number 10857) Flow in the form of funded research and is an unpaid consultant for Ambu, Covidien and SonarMed. Funding source This work was supported by Revolutionary Medical Devices, Inc. (Covidien-Medtronic) (Project number 11357), in conjunction with Covidien-Medtronic (Project number 11023). Acknowledgements Dr. Cai's research was supported by the National Institutes of Health's Clinical and Translational Science Award grant (UL1 TR000371), awarded to the University of Texas Health Science Center at Houston in 2012 by the National Center for Clinical and Translational Sciences. Appendix Abbreviations AA AE ADE ASA BMI BP CPAP CRF CO2
Anesthetist Assistant Adverse Event Adverse Device Effect American Society of Anesthesiology Body Mass Index Blood Pressure Continuous Positive Airway Pressure Case Report Form Carbon Dioxide
Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054
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DMV ECG ETCO2 ETT FRC HIPAA IRB OSA PACU PD PHI SpO2
Difficult Mask Ventilation Electrocardiogram End-tidal Carbon Dioxide Endotracheal Tube Functional Residual Capacity Health Insurance Portability and Accountability Act Institutional Review Board Obstructive Sleep Apnea Post Anesthesia Care Unit Protocol Deviation Protected Health Information Blood Oxygen Saturation
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Please cite this article in press as: S. Ghebremichael, et al., Evaluation of SuperNO2VA™ mask technology in a clinical setting: A pilot study, Trends in Anaesthesia and Critical Care (2017), https://doi.org/10.1016/j.tacc.2017.09.054