Does the incidence of sore throat postoperatively increase with the use of a traditional intubation blade or the GlideScope?

Journal of Clinical Anesthesia (2015) xx, xxx–xxx

Original contribution

Does the incidence of sore throat postoperatively increase with the use of a traditional intubation blade or the GlideScope?☆,☆☆,★,★★,☆☆☆,☆☆☆☆ Dennis J. Cirilla II DO (Assistant Professor of Anesthesiology)a,⁎, Jason Ngo BS (Medical Student, 4th year)b , Vadim Vaisman DO (Assistant Professor of Anesthesiology)a , Caroline Daly MD (Resident in Anesthesiology)a , Ashar Ata MBBS, MPH (Staff Statistician)c , Michael Sandison MD (Professor of Anesthesiology)a , Kevin Roberts MD (Chair)a a

Department of Anesthesiology, Albany Medical Center, Albany, NY, USA Albany Medical College, Albany, NY, USA c Department of Surgery, Albany Medical Center, Albany, NY, USA b

Received 11 May 2014; revised 5 February 2015; accepted 9 June 2015

Keywords: GlideScope; Macmiller; Macintosh; Intubation; Sore throat; Pharyngitis; Postoperative; Endotracheal tube

Abstract Study Objective: The GlideScope video-guided laryngoscope is an alternative standard of care for rescue laryngoscopies when direct laryngoscopy is unsuccessful. During postoperative checks by an anesthesiologist, it was noticed that patients who reported sore throat often required GlideScope laryngoscopy. Consequently, it is difficult to determine whether postoperative sore throats are caused by irritation inflicted by multiple laryngoscopic attempts or the actual utilization of the GlideScope itself. The goal of this study was to determine whether the use of the GlideScope leads to a greater or lesser incidence of sore throat when compared with traditional laryngoscope blades used for intubation. Design: Eligible patients scheduled for elective inpatient surgeries requiring endotracheal tube intubation were enrolled into this single-blinded prospective cohort study. χ2 Test, Fisher exact test, and t tests were used to compare differences across the primary end point and other demographic categories.

☆ Contribution: Dennis J. Cirilla II and Vadim Vaisman helped design the study, conduct the study, collect data, and prepare the manuscript. Jason Ngo and Caroline Daly helped conduct the study, collect data, analyze data, and prepare the manuscript. He is the archival author. Ashar Ata helped analyze data and perform statistical support. Michael Sandison helped provide manpower and resources. Kevin Roberts helped conduct the study. ☆☆ Attestation: Dennis J. Cirilla II and Vadim Vaisman approved the final manuscript. In addition, they attest to the integrity of the original data and the analysis reported in this manuscript. ★ Conflicts of interest: None for all authors. ★★ Funding: Internally funded by the Department of Anesthesiology, Albany Medical Center, Albany, NY. ☆☆☆ Did a Section Editor solicit this submission? No. ☆☆☆☆ IRB: Margo Fairbairn-Newton, IRB Administrator, Institutional Review Board, Albany Medical Center, 43 New Scotland Avenue, R-102, Albany, NY 12208. Tel.: 518-262-5997. [email protected] ⁎ Corresponding author at: Department of Anesthesiology, Albany Medical Center, 43 New Scotland Ave, MC-131, Albany, NY 12208, USA. Tel.: +1 518 262 4302. E-mail addresses: [email protected] (D.J. Cirilla), [email protected] (J. Ngo), [email protected] (V. Vaisman), [email protected] (C. Daly), [email protected] (A. Ata), [email protected] (M. Sandison), [email protected] (K. Roberts).

http://dx.doi.org/10.1016/j.jclinane.2015.06.005 0952-8180/© 2015 Elsevier Inc. All rights reserved.

2

D.J. Cirilla II et al. Setting: Operating rooms and postanesthesia recovery unit, Albany Medical Center, Albany, NY Patients: There were a total of 151 patients with American Society of Anesthesiologists grades 1 to 3 included in the study. Interventions: Eighty-one patients were randomized to a control group that received traditional laryngoscopy via Macintosh/Miller blades and 70 patients received video-guided intubation via the GlideScope. Measurements: The incidence of postoperative sore throat was recorded via a yes/no questionnaire within 24 hours after extubation. Secondary parameters such as provider type, sex, and perceived difficulty were also recorded. Main results: There was no significant difference in the proportion of patients reporting sore throat by type of blade used (Mac/Miller 36.3% vs GlideScope 32.4%, P = .619). For secondary outcomes, women were significantly more likely to report sore throat as compared with men (men 24.3% vs women 43.2%, P = .015), and the provider type was significantly associated with the occurrence of postoperative sore throat (attendings 26.8% vs certified registered nurse anesthetists 52.3% vs third-year clinical anesthesia residents 30%, P = .012). Conclusions: Use of the GlideScope videolaryngoscopy was not significantly associated with increased occurrence of postoperative sore throat when compared with traditional intubation techniques. Our results may enable more trainees to acquire intubation skills with the GlideScope during an initial intubation attempt in patients with American Society of Anesthesiologist grades 1 to 3, with optimization of patient satisfaction in respect to postoperative sore throats. In addition, a provider's choice of intubation technique based on either Macintosh/ Miller blades or the GlideScope does not significantly impact a patient's risk of postoperative sore throat. © 2015 Elsevier Inc. All rights reserved.

1. Introduction Use of the Macintosh/Miller (Moore Medical, Farmington, CT) blade is current standard of care for first-line intubations of patients with no predicted difficult airways. Use of the GlideScope (Verathon, Bothell, WA) has been validated through numerous studies that have shown a comparable or superior glottic view with use of the GlideScope when compared with Macintosh/Miller direct laryngoscopy methods [1]. GlideScope videolaryngoscopy has evolved into standard of care for patients who require a rescue intubation after a primary attempt with direct Macintosh/Miller blade laryngoscopy has failed [2]. During postoperative checks, it was noticed that patients who reported sore throat often required intubation with the GlideScope. The initial attempt with direct laryngoscopy on a difficult airway may require use of McGill forceps, which increases the chance of upper airway injury prior to the rescue attempt with the GlideScope. Consequently, it is difficult to determine whether patients' reports of postoperative sore throat are caused by the irritation of the multiple laryngoscopic attempts required in patients where the GlideScope was needed as a rescue method, or whether it is due to the actual use of the GlideScope itself. Previous studies suggest that use of a GlideScope in both manikins and humans decreases the likelihood of upper airway injury by decreasing the mean force and homogenizing the force distribution during laryngoscopy when compared with the Macintosh laryngoscope [3,4]. Another study found that the incidence of postoperative moderate or severe sore throat was significantly reduced with use of the GlideScope when compared with direct laryngoscopy in nasotracheal intubation [5]. However, other studies have shown increased incidence of

postoperative sore throat with GlideScope usage when compared with other videolaryngoscopes and conventional Macintosh laryngoscope as a primary laryngoscopy method [6]. In light of these studies, none have attempted a direct comparison of a GlideScope with conventional Macintosh/ Miller laryngoscope blades with incidence of sore throat as a primary outcome of interest. The purpose in this study is to determine whether there is a difference in the incidence of postoperative sore throat when using the GlideScope vs a traditional intubation blade involving patients who are not anticipated to have a difficult airway. Exclusion of patients with difficult airways allows us to perform direct comparisons with the GlideScope and conventional direct laryngoscopy without compromising standard of care or increasing patient risk.

2. Methods This study was approved by the institutional review board of the Albany Medical College. Study enrollment commenced in June 2012. Written and informed consent was obtained from all subjects by study personnel and witnessed by another staff member if the patient gave verbal consent. This single-blinded prospective cohort study evaluated the incidence of sore throat for patient groups separately exposed to either conventional Macintosh/Miller blade laryngoscopy or to GlideScope videolaryngoscopy. The null hypothesis is that there is no difference in incidence of sore throat when using the GlideScope vs a standard intubation blade. The primary study end point was 24 hours postoperatively after evaluation of sore throat was completed. Using a sample size of 75 subjects per group will allow us to detect a 6% difference between samples,

3 assuming the background rate of postoperative sore throats after outpatient surgery is 12.1% [7,8]. This allows for a type I error rate of 0.05 and a power of 0.85 while also accounting for expected patient dropout during the course of the study. All patient enrollment occurred at the Albany Medical Center Hospital, a 651-bed tertiary care center in Albany, NY. Inclusion and exclusion criteria are detailed in Figure. Eligible patients were randomized to receive either traditional Macintosh/Miller laryngoscopy or GlideScope video-assisted laryngoscopy after anesthesia induction was started and prior to intubation with an appropriate endotracheal tube. Providers completed a data collection sheet which included the type of laryngoscopy used, provider type (anesthesiologist, certified registered nurse anesthetist [CRNA], or third-year clinical anesthesia resident [CA-3]), patient age, sex, surgical procedure scheduled, a standard-

Figure

ized airway assessment (American Society of Anesthesiologists [ASA] score, Mallampati score, thyromental distance, upper lip bite score, degree of retrognathia, adequate neck range of motion, and anticipation of difficulty), number of attempts at successful laryngoscopy, and whether noticeable airway trauma was found after intubation; all data forms were returned to a secure mailbox. On the next postoperative day, study personnel would follow-up with enrolled subjects to evaluate the presence or absence of sore throat as assessed via a simple yes/no questionnaire by a board-certified anesthesiologist who verbally queried the patients on the presence or absence of sore throat with a “yes/no” reply; our interviewer was blinded as to which anesthesia provider had performed the intubation and the laryngoscopy method used. Data were regularly collected from the secure mailbox and entered onto a Microsoft Excel spreadsheet.

Inclusion and exclusion criteria for all eligible patients in the study.

4 Demographics and patient characteristics were compared by type of blade used to verify if there were any patient or provider characteristics that were associated with or that influenced the type of blade used. The effect of type of blade used on the occurrence of sore throat was evaluated by proportion of patients with sore throat by type of blade used and across various other variables that might have potentially had an influence on the occurrence of sore throat. χ2 Test, Fisher exact test, and t tests were used to compare differences across variable categories. Statistical significance was set at a .05 level of significance. Statistical software Stata 11.0 was used for analysis (Stata Corp, College Station, TX).

3. Results There were 151 patients in our study, of which the GlideScope blade was used on 70 patients and the Macintosh/ Miller blade was used on 81. Table 1 describes the distribution of the type of blade used for various patient characteristics. None of the patient characteristics were associated with the use of one particular type of blade—hence, assignment of patients to type of laryngoscopy received was evenly distributed. Table 2 describes the rate of sore throat by type of blade and patient characteristics. There were no significant differences in the proportion of patients reporting sore throat by type of blade used (Mac/Miller 36.3% vs GlideScope 32.4%, P = .619). Women were significantly more likely to report sore throat as compared with men (men 24.3% vs women 43.2%, P = .015). The provider performing the laryngoscopy was also significantly associated with the occurrence of patient-reported postoperative sore throat (anesthesiologists 26.8% vs CRNAs 52.3% vs CA-3 residents 30%, P = .012). ASA score, Mallampati rating, thyromental distance, lip bite rating, retrognathia rating, neck range of motion, perceived provider difficulty, number of attempts, and presence of postoperative laryngeal trauma were not significantly associated with the occurrence of postoperative sore throat. Relative risk ratios in respect to sex show that women are 1.779 times more likely than men to have postoperative sore throats (P = .02; 95% confidence interval, 1.096-2.889). Relative risk ratios in respect to provider show that CRNAs (2) are 1.95 times more likely than anesthesiologists to result with postoperative sore throats (P = .003; 95% confidence interval, 1.262-3.013). Relative risk ratios for CA-3 residents compared with attendings were not significant.

4. Conclusions The GlideScope videolaryngoscope is a valuable tool in airway management that affords users comparable or superior largyngeal management in patients with normal airways and patients with potentially difficult airways as rated by such metrics as the Mallampati classification scale. Although the

D.J. Cirilla II et al. Table 1

Demographic data. No. of patients

Sex Mean age (y) Provider

ASA

Mallampati

Thyromental LipBite

Retrognathia

NeckROM Difficulty

Trauma No. of attempts

Male Female Mac/Miller GlideScope 1 2 3 1 2 3 4 1 2 3 4 1 2 1 2 3 1 2 3 1 2 1 2 3 4 1 2 1 2 3

% Receiving GlideScope

70 48.6 81 45.7 57.1 ± 1.7 53.6 ± 1.5 97 47.4 44 47.7 10 40 6 33.3 69 49.3 72 45.8 4 50 37 40.5 79 44.3 33 63.6 2 0 132 45.5 19 57.9 91 42.9 58 53.5 2 50 126 46 24 50 1 100 147 46.3 4 75 82 46.3 52 44.2 16 56.3 1 100 3 66.7 148 46.6 130 46.2 20 55 1 0

P .723 .278 .899

.886

.098

.31 .449

.532

.256 .604

.491 .487

traditional MacIntosh and Miller laryngoscopy blades are still the predominant first-line laryngoscopy method used in most cases, familiarity with the GlideScope will be a crucial skill for residents in anesthesiology and in emergency medicine. Novice users with formal instruction have had high success rates with acquiring superior laryngeal views while using the GlideScope. Nonetheless, inexperienced users may encounter difficulty using the more acutely angled GlideScope stylet to guide the endotracheal tube to the glottis and into the trachea [1]. Success rates have increased with experience and training [9], underscoring the importance of exposing novice users to the GlideScope system as frequently as possible during their training. Concerns with complications associated with GlideScope usage, as previously mentioned, have arisen when considering daily implementation of the GlideScope in routine airway management cases. Residency training programs have a duty to ensure that no additional harm is incurred by the patient in the interest of physician education, which is a

5 Table 2

Primary and secondary outcomes.

Blade Sex Provider

ASA

Mallampati

Thyromental LipBite

Retrognathia

NeckROM Difficulty

No. of attempts

Trauma

Mac/Miller GlideScope Male Female 1 2 3 1 2 3 4 1 2 3 4 1 2 1 2 3 1 2 3 1 2 1 2 3 4 1 2 3 1 2

No. of patients

% Sore throat present

P

80 71 70 81 97 44 10 6 69 72 4 37 79 33 2 132 19 91 58 2 126 24 1 147 4 82 52 16 1 130 20 1 3 148

36.3 32.4 24.3 43.2 26.8 52.3 30 16.7 36.2 32 75 35.1 32.9 36.4 50 35.6 26.3 33 36.2 50 36.5 25 0 34.01 50 31.7 40.4 31.3 0 33.9 35 100 0 35.1

.619 .015 .012

.256

.949

.426 .826

.425

.507 .641

.382

.205

primary concern when less commonly used equipment is introduced into an program curriculum. Our study demonstrates that one potential concern—sore throat incidence after GlideScope usage—does not significantly occur with greater or lesser prevalence when compared with the prevailing usage of the Macintosh or Miller blades. This demonstration allows more latitude when choosing to let novice users gain experience with the GlideScope as a primary laryngoscopy technique under closely supervised conditions by an experienced GlideScope practitioner. The GlideScope allows for high success rates of visualization in normal airways, anticipated difficult airways, and repeat intubation after failed direct laryngoscopy [9], and early proficiency in GlideScope usage will allow users great flexibility in a wider range of patient scenarios. Repeated intubations after failed direct laryngoscopy was not significantly associated with sore throat incidence in our study, a finding that is supported by other authors [2] and that further supports the role of the GlideScope as an appropriate rescue

device. Interestingly, there was no statistically significant correlation between the anesthesiologists' assessment of difficult airways and postoperative incidence of sore throats; further research is warranted to determine the place and use of preoperative airway assessments on predicting postoperative complications of intubation. Certain patient demographic traits must still be considered when deciding whether to allow increased use of GlideScope videolaryngoscopy in practice settings. This study also demonstrated that female patients have a statistically significant incidence of sore throat regardless of whether traditional Macintosh/Miller or GlideScope videolaryngoscopy was used. Such findings have been demonstrated in previous studies [10], but a specific etiology for such increased incidence has not been elucidated to date. Because the use of the GlideScope does not significantly impact postoperative sore throat incidence between sexes, other factors such as endotracheal tube size or anatomical variance in tracheal size between sexes are reasonable to consider. Several anesthesiologists have voiced their concern in using GlideScope videolaryngoscopy as a first-line intubation method for anticipated difficult airways, citing anecdotal case studies, opinions, or manikin-based studies that indicate increased risk of postoperative sore throat due to oropharyngeal injury [11]. However, no randomized controlled trials with significant live human patient enrollment have been performed to address this question. Our study, with our high power in subject enrollment and analysis of intubation method on normal airways, sets a baseline of comparison that addresses whether using traditional or GlideScope laryngoscopy may lead to postoperative sore throats in normal airways. By excluding difficult airways, we explored whether the incidences of oropharyngeal injury reported by several anethesiologists may stem from actual usage of the GlideScope laryngoscopy or whether such reported injuries could possibly result from the inherent difficulties in inducing anesthesia on a patient with a difficult airway (eg, difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, or multiple intubation attempts due to a failed airway). Future follow-up studies, using our results as a baseline, may then be created to determine which factors may render a patient with a difficult airway more susceptible to oropharyngeal injury.

Acknowledgments Funding and support personnel were provided by the Department of Anesthesiology, Albany Medical Center, Albany, NY.

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