- Email: [email protected]
Airway management for cesarean delivery performed under general anesthesia
Accepted Manuscript Original Article Airway Management for Cesarean Delivery Performed Under General Anesthesia S. Rajagopalan, M. Suresh, S.L. Clark, B. Serratos, S. Chandrasekhar PII: DOI: Reference:
S0959-289X(16)30102-9 http://dx.doi.org/10.1016/j.ijoa.2016.10.007 YIJOA 2507
To appear in:
International Journal of Obstetric Anesthesia
Received Date: Revised Date: Accepted Date:
17 July 2016 29 September 2016 20 October 2016
Please cite this article as: Rajagopalan, S., Suresh, M., Clark, S.L., Serratos, B., Chandrasekhar, S., Airway Management for Cesarean Delivery Performed Under General Anesthesia, International Journal of Obstetric Anesthesia (2016), doi: http://dx.doi.org/10.1016/j.ijoa.2016.10.007
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
IJOA 16-00165 ORIGINAL ARTICLE Airway management for cesarean delivery performed under general anesthesia S. Rajagopalan,a M. Suresh,a S. L. Clark,b B. Serratos,a S. Chandrasekhar a a
Department of Anesthesiology, Baylor College of Medicine, Houston, Texas, USA
b
Department of Obstetrics and Gynecology, Maternal Fetal Medicine, Baylor College of Medicine
Houston, Texas, USA
Short title: Airway management for cesarean delivery
Correspondence to: Suman Rajagopalan MD, Department of Anesthesiology, Baylor College of Medicine, One Baylor Plaza, MS: BCM-120, Houston, Texas 77030 E-mail address: [email protected]
2
ABSTRACT Background: With the increasing popularity of neuraxial anesthesia, there has been a decline in the use of general anesthesia for cesarean delivery. We sought to examine the incidence, outcome and characteristics associated with a failed airway in patients undergoing cesarean delivery under general anesthesia. Methods: A retrospective review of airway management in women undergoing cesarean delivery under general anesthesia over an eight-year period from 2006–2013 at an academic medical center was conducted. Results: During the study period, 10 077 cesarean deliveries were performed. Neuraxial anesthesia was used in 9382 (93%) women while general anesthesia was used in 695 (7%). Emergent cesarean delivery was the most common indication for general anesthesia. Failed intubation was encountered in only three (0.4%) women, who were successfully managed with a laryngeal mask airway. The overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666) and general anesthesia was continued in all cases. There were no adverse maternal or fetal outcomes directly related to failed intubation. Conclusion: Advances in adjunct airway equipment, availability of experienced anesthesiologist and simulation-based teaching of failed airway management in obstetrics may have contributed to our improved maternal outcomes in patients undergoing cesarean delivery under general anesthesia.
Keywords: Cesarean delivery; General anesthesia; Failed intubation
Introduction Difficulty in airway management and its associated risk of aspiration, maternal and fetal hypoxia are major causes of general anesthesia (GA)-related morbidity and mortality in patients undergoing cesarean delivery (CD).1,2 In the USA, anesthesia-related maternal mortality is estimated to be 0.12 per 100 000 live births.3 The incidence of failed tracheal intubation in pregnant women has been estimated to be five-to-seven-fold higher as compared to the non-pregnant population.4-7 In the last two decades, the use of GA for CD has decreased significantly and neuraxial techniques have become the preferred method.8 With the decline in the use of GA in pregnant women, there is concern that training in airway management in this population may be suboptimal.9,10 This could lead to an increased incidence of failed intubation, and associated maternal/fetal morbidity or mortality.
3
Importantly, this may impact on the anesthetic management in healthcare settings where providers of varying levels of experience and training provide anesthesia services. In this study, we sought to review indications for GA in CD and any associated airway complications in our academic center.
Methods This study was conducted under a research protocol approved by the Institutional Review Board of Baylor College of Medicine (BCM), Houston, TX and Harris Health System, Houston, TX. Ben Taub General Hospital, the primary academic teaching hospital of BCM, maintains a database on all CDs performed including the type of anesthesia. From this database, we identified all individuals who underwent CD under GA from January 2006 to December 2013. From the electronic medical records, information regarding history of pre-existing or pregnancy-related disorders, height, weight, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, indication for GA, preoperative Mallampati classification, neck movements, airway management techniques including number of attempts at laryngoscopy, Cormack and Lehane laryngoscopic score and complications related to airway management were collected. Failed tracheal intubation is typically defined as the inability to place a tracheal tube after multiple attempts.11 Although, there is no standard definition of failed intubation in obstetrics, it has generally been defined as failure to achieve tracheal intubation with a single dose of succinylcholine.4,5 It has also been described as unsuccessful attempts at placement of a tracheal tube using either direct laryngoscopy or alternative intubating equipment, the need to proceed with surgery with a non-elective unsecured airway or the need to abort intubation or surgery and awaken the woman before surgery.7,12 For the analysis of our data we used the definition “inability to secure the airway after a single dose of succinylcholine and no more than two attempts at intubation using conventional laryngoscope or an alternative airway device”.13
Results From 2006 to 2013, a total of 38 251 deliveries were performed of which 10 077 (26.3%) were CD (Table 1). Neuraxial anesthesia was employed in 9382 patients (93%) whereas GA was used in 695 (7%). Indications for GA are summarized in Table 2. Emergent CDs performed due to fetal indications (non-reassuring fetal status, fetal bradycardia, cord prolapse, and prolapse of fetal limbs)
4
or maternal causes (placenta previa, placental abruption, eclampsia, previous uterine surgery, trauma, and uterine rupture) accounted for the majority of cases performed under GA (n=402, 57.8%). This result was fairly consistent over the duration of the study. Limitation of time to perform neuraxial techniques in the emergent situation was the primary reason for choosing GA in these individuals. Failed neuraxial block was the second most common reason (n=160, 23%) for CD being performed under GA. The overall failure rate of neuraxial block was 1.7% (160 out of 9542). General anesthesia was electively performed in 17.5% of patients due to refusal of a neuraxial technique, presence of placenta accreta, increta or percreta, spinal abnormalities or coagulopathy. In 11 (1.5%) patients, neuraxial anesthesia was converted to GA intraoperatively, secondary to surgical complications that required securing the airway for prolonged surgery. Most patients (n=673; 96.8%) were successfully intubated by direct laryngoscopy and were not considered a difficult intubation. Nearly 94% were intubated on the first attempt, while a second attempt by a more experienced person, or the use of a different laryngoscopic blade was required in 38 (5.6%) patients (Table 3). An Eschmann’s gum elastic bougie was successfully used in three patients during the first or the second attempt at intubation. Since intubation was successful with the bougie in the first two attempts, these patients did not meet the criteria for failed intubation. In 10 patients, a videolaryngoscope was used (Glidescope n=3, C-MAC n=7) as an alternative to direct laryngoscopy as the intubation was predicted to be difficult. Elective awake-fiberoptic intubation was performed in seven patients (1%) with an anticipated difficult airway. Most patients requiring awake-fiberoptic intubation had a non-reassuring airway exam with Mallampati scores of >III, a short, thick neck, or restricted neck movement (Table 4). There were three cases of failed tracheal intubation before 2010 (0.43%); all were successfully rescued with a laryngeal mask airway (LMA). In two patients, a tracheal tube was successfully placed through a Fastrach Intubating LMA while in the third patient oxygenation was maintained through the LMA. General anesthesia was chosen in two of the patients with failed intubation due to the emergent nature of the CD while a failed neuraxial technique was the reason in the third. All three patients had higher Mallampati scores but good mouth opening and full neck movements. Hence, a preoperative exam did not predict difficulty with intubation. None of these patients showed evidence of aspiration of gastric contents and were successfully extubated at the end
5
of surgery. There were no cases requiring a surgical airway or maternal mortality from GA for CD during the study period.
Discussion In this study, over a period of eight years the overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666). Studies that have evaluated the incidence of failed intubation during the same study period have reported similar results.14-16 A systematic review of 27 studies that collectively included over 88 000 individuals revealed that the incidence of failed tracheal intubation was 1 in 443 and that this was relatively unchanged over the years.7 Our facility represents a large center consisting of providers with varying levels of training who care for a diverse population of patients. Results from retrospective analyses of large datasets from an unselected patient population in such settings are likely to be applicable to clinical practice. The proportion of CDs in our cohort (26%) was lower than the national average of 33% reported by the Centers for Disease Control and Prevention (CDC) in 2013.17 The incidence of GA for CD was approximately 7%. As expected, the majority of cases performed under GA were for emergency CD. The second most common reason was failed neuraxial technique, which contributed to approximately one quarter of cases. About 97% of the patients were intubated by direct laryngoscopy either at the first or second attempt. As our facility is a teaching hospital, an anesthesia resident or a student nurse anesthetist are typically the first to attempt intubation. Senior residents or attending anesthesiologists take over if the initial attempt is unsuccessful. Complications related to anesthesia rank tenth among the causes of pregnancy-related deaths in the USA.18 Airway-related complications associated with failed intubation and the inability to ventilate or oxygenate following induction of GA are major causes for anesthesia-related mortality.3 The anatomic and physiologic changes during pregnancy place the parturient at higher risk for desaturation, difficult mask ventilation and failed intubation. In addition, these changes predispose to a higher risk of aspiration of gastric contents during induction or immediately following extubation. In recent years, awareness of airway-related complications has prompted an increase in the use of neuraxial techniques. In the USA the incidence of GA for CD has declined and has been reported to be between 0.5% and 7%.19-21 It is likely that medicolegal factors also influence the decision to use GA. The American Society of Anesthesiology (ASA) Closed Claims Analysis (1990–2003) in Obstetric Anesthesia reported that claims for maternal death and permanent brain damage were
6
higher for difficult intubation (25%) and maternal hemorrhage (29%) following GA for CD.22 Thus, use of GA is currently limited to emergent CD in situations when a neuraxial technique is contraindicated or in patients who refuse neuraxial anesthesia. An immediate clinical consequence of failed intubation that needs to be addressed is whether to continue with GA. Some studies have reported a high percentage of patients with failed intubation who were awakened from anesthesia.4,23,24 In our cohort, we successfully used an LMA as a rescue device in all three patients with a failed intubation and where GA was continued. The widespread availability of videolaryngoscopes and LMAs as rescue devices has improved airway management and is likely to result in continuation of GA in most patients with a failed intubation. The ASA algorithm for difficult obstetric airway management has incorporated the LMA as the rescue device in cannot intubate and cannot oxygenate situations. Although the LMA does not prevent the risk of aspiration, it is proven to be a valuable rescue device in maintaining ventilation and oxygenation in difficult airway situations.14,15,25,26 The ASA Closed Claim Analysis noted that use of LMA as a rescue device for unanticipated difficult airway has resulted in a decrease in the incidence of brain death and mortality.22 Another device that has become a first-line rescue for failed intubation is the video laryngoscope. It is interesting to note that during our study period, we had no cases of failed intubation after 2010, the time at which we added videolaryngoscopes to our difficult airway cart. Videolaryngoscopes provide an excellent view of the glottis and vocal cords and increase the success rate in unanticipated difficult intubation. The success rate of intubation on first attempt with the CMAC has been shown to be higher when compared to direct laryngoscopy in patients with a predicted difficult airway.27,28 Although there are no published studies clearly demonstrating the effectiveness of videolaryngoscopes as a rescue device in the obstetric population, it has been utilized to secure the airway in patients where conventional direct laryngoscopy was unsuccessful.29,30 There has been a decline in maternal mortality related to GA in recent years. Hawkins et al. demonstrated that anesthesia-related maternal mortality during CD decreased from 16.8 deaths per million GAs between 1991 and 1995 to 6.5 deaths per million GAs between 1997 and 2002.3 This decline could be attributed to heightened awareness of failed intubation, utilization of a difficult airway algorithm and early use of advanced airway devices.13,31 Our study, and others conducted over the last eight years, reported no maternal deaths related to GA in spite of instances of failed intubation.10,14-16
7
At our institution, we have adopted several measures to improve the maternal outcomes for CD performed under GA. Firstly, a faculty anesthesiologist is immediately available in the labor and delivery suite for round-the-clock supervision of trainees. Secondly, we have made sure that airway adjunct equipment like the LMA, videolaryngoscope and fiberoptic scope is readily available. Finally, we have formally incorporated didactic simulation scenarios pertaining to the difficult obstetric airway in the teaching curriculum for trainees. Use of simulation training has been endorsed by the UK Confidential Enquiries into Maternal Deaths 2003–2005 and 2006–2008 to improve performance in the management of emergencies.32,33 With the decline in experience of GA for CD, simulating the scenario followed by debriefing is an alternate way of improving skills.34 The results from analyses in this study have to be interpreted in the context of limitations of the dataset. All data points were collected from a retrospective review of medical records. As with any retrospective study, data collection was not performed in a standardized manner. Thus, it is possible that physicians graded Mallampati scores, neck movements, and Cormack-Lehane laryngoscopic scores differently. Practice preferences of physicians may have influenced employment of videolaryngoscope as the initial method of choice for intubation, which may have underestimated the incidence of failed intubations. Finally, the event rate of failed intubation was low; precluding statistical analyses that could identify potential correlates associated with failed intubation. In conclusion, our results add to the growing body of literature that demonstrates that in spite of the relatively stable rates of failed intubation over the years, maternal mortality with GA is declining. Enhanced awareness of the ASA difficult airway algorithm, availability of newer airway devices, presence of an experienced anesthesia provider, improvement in skills and simulation training of failed airway in obstetrics have resulted in continuation of GA in most cases of failed intubation without adverse maternal outcomes.
Disclosure This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. None of the authors have any conflicts
References 1.
Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse respiratory event in anesthesia: a closed claims analysis. Anesthesiology 1990; 72:828-33.
8
2.
Ezri T, Szmuk P, Evron S, Geva D, Haqay Z, Katz J. Difficult airway in obstetric anesthesia: a review. Obstet Gynecol Surv 2001; 56:631-41.
3.
Hawkins JL, Chang J, Palmer SK, Gibbs CP, Callaghan WM. Anesthesia-related maternal mortality in the United States: 1979 -2002. Obstet Gynecol 2011; 117:69-74.
4.
Hawthorne L, Wilson R, Lyons G, Dresner M. Failed intubations revisited: 17-yr experience in a teaching maternity unit. Br J Anaesth 1996; 76:680-684.
5.
Barnardo PD, Jenkins JG. Failed tracheal intubation in obstetrics: a 6-year review in a UK region. Anaesthesia. 2000; 55:690-4.
6.
Rahman K, Jenkins JG. Failed tracheal intubation in Obstetrics: no more frequent but still managed badly. Anaesthesia 2005; 60:168-71.
7.
Kinsella SM, Winton AL, Mushambi MC, et al. Failed tracheal intubation during obstetric general anaesthesia: a literature review. Int J Obstet Anesth 2015; 24:356-74.
8.
Bowring J, Fraser N, Vause S, Heazell AE. Is regional anaesthesia better than general anaesthesia for caesarean section? J Obstet Gynaecol 2006; 26:433-4.
9.
Johnson RJ, Lyons GR, Wilson RC, Robinson RPC. Training in Obstetric general anesthesia; a vanishing art? Anaesthesia 2000; 55:179-83.
10. Djabatey EA, Barclay PM. Difficult and failed intubation in 3430 obstetric general anesthetics. Anaesthesia 2009; 64:116. 11. Apfelbaum JL, Hagberg CA, Caplan RA, et al; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013; 118:251-70. 12. McKeen DM, George RB, O’Connell CM, et al. Difficult and failed intubation: incident rates and maternal, obstetrical and anesthetic predictors. Can J Anesth 2011;58:514-24. 13. Suresh MS, Wali A, Crosby ET. Difficult and failed intubation: Strategies, prevention and management of airway-related catastrophes in obstetrical patients. In: Suresh M, Segal BS, Preston RL, Fernando R, Mason CL. Shnider and Levinson’s Anesthesia for obstetrics 5th edition; 2012. 363-402. 14. Tao W, Edwards JT, Tu F, Xie Y, Sharma SK. Incidence of unanticipated difficult airway in obstetric patients in a teaching institution. J Anesth 2012; 26:339-45. 15. Quinn AC, Milne D, Columb M, Gorton H, Knight M. Failed tracheal intubation in obstetric
9
anaesthesia: 2 yr national case-control study in the UK. Br J Anaesth 2013; 110:74-80. 16. Nafisi S, Darabi ME, Rajabi M, Afshar M. General anesthesia in cesarean sections: a prospective review of 465 cesarean sections performed under general anesthesia. Middle East J Anaesthesiol 2014; 22:377-84. 17. Martin JA, Hamilton BE, Ventura SJ, Osterman MJ, Mathews TJ. Births: final data for 2011. Natl Vital Stat Rep 2013; 62:1-69. 18. Creanga AA, Berg CJ, Syverson C, Seed K, Bruce FC, Callaqhan WM. Pregnancy-related mortality in the United States, 2006-2010. Obstet Gynecol 2015; 125:5-12. 19. Palanisamy A, Mitani AA, Tsen LC. General anesthesia for cesarean delivery at a tertiary care hospital from 2000 to 2005: a retrospective analysis and 10-year update. Int J Obstet Anesth 2011; 20:10-6. 20. Tsen LC, Pitner R, Camann WR. General anesthesia for caesarean section at a tertiary care hospital 1990–1995: indications and implications. Int J Obstet Anesth 1998; 7:147-52. 21. Bloom SL1, Spong CY, Weiner SJ, et al. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Complications of anesthesia for cesarean delivery. Obstet Gynecol 2005; 106:281-287. 22. Davies JM, Posner KL, Lee LA, Cheney FW, Domino KB. Liability associated with obstetric anesthesia: a closed claims analysis. Anesthesiology 2009; 110:131-9. 23. Lyons G. Failed intubation. Six years’experience in a teaching maternity unit. Anaesthesia 1985; 40:759-62. 24. Shibli KU, Russell IF. A survey of anaesthetic techniques used for caesarean section in the UK in 1997. Int J Obstet Anesth 2000; 9:160-7. 25. Bailey SG, Kitching AJ. The laryngeal mask airway in failed obstetric tracheal intubation. Int J Obstet Anesth 2005; 14:270-1. 26. McDonnell NJ, Paech MJ, Clavisi OM, Scott KL. ANZCA trials group. Difficult and failed intubation in obstetric anaesthesia: an observational study of airway management and complications associated with general anaesthesia for caesarean section. Int J Obstet Anesth 2008; 17:292–97. 27. Aziz MF, Dillman D, Fu R, Brambrink AM. Comparative effectiveness of the C-MAC video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway. Anesthesiology 2012; 116:629-36.
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28. Sakles JC, Mosier J, Chiu S, Cosentino M, Kalin L. A comparison of the C-MAC videolaryngoscope to the Macintosh direct laryngoscope for intubation in the emergency department. Ann Emerg Med 2012; 60:739-48. 29. Piepho T, Fortmueller K, Heid FM, Schmidtmann I, Werner C, Noppens RR. Performance of the C-MAC video laryngoscope in patients after a limited glottic view using Macintosh laryngoscopy. Anaesthesia 2011; 66:1101-5. 30. Kilicaslan A, Topal A, Tavian A, Erol A, Otelcioglu S. Effectiveness of the C-MAC video laryngoscope in the management of unexpected failed intubations. Braz J Anesthesiol 2014; 64:62-65. 31. Mushambi MD, Kinsella SM, Popat M, et al. Obstetric Anaesthetists’ Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics. Anaesthesia 2015; 70:1286-306. 32. Confidential Enquiries into Maternal and Child Health (CEMACH) Saving Mother’s Lives: Reviewing maternal deaths to make motherhood safer: 2003-2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. London. CEMACH. 33. Centre for Maternal and Child Enquiries (CMACE). Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer: 2006–08. The Eighth Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. BJOG 2011;118(Suppl. 1):1–203. 34. Balki M, Chakravarty S, Salman A, Wax RS. Effectiveness of using high-fidelity simulation to teach the management of general anesthesia for Cesarean delivery. Can J Anaesth 2014; 61:92234.
11 Table 1 Number of cesarean deliveries under general anesthesia 2006 2007 2008 2009 Total deliveries 6372 5788 5417 5368 Cesarean deliveries 1608 1495 1431 1390 (25.2%) (25.8%) (26.4%) (25.9%) Cesarean deliveries 117 116 87 96 under GA (7.27%) (7.76%) (6.08%) (6.91%) Data are number (%)
2010 4305 1150 (26.7%) 78 (6.67%)
2011 3671 1117 (30.4%) 66 (5.91%)
2012 3744 964 (25.7%) 63 (6.5%)
2013 3586 922 (25.8%) 72 (7.8%)
Tot 38,2 10 0 (26.3 69 (6.89
12 Table 2 Indications for general anesthesia for cesarean delivery 2006 2007 2008 2009 2010 Total GA number 117 116 87 96 78 Elective 7 12 12 26 16 Failed neuraxial 17 29 23 24 20 block Intraoperative 0 0 0 2 4 conversion Emergency 93 75 52 44 38 GA: general anesthesia
2011 66 13 13
2012 63 21 12
2013 72 15 22
Total 695 122 (17.5%) 160 (23%)
1
2
2
11 (1.5%)
39
28
33
402 (57.8%)
13 Table 3 Airway management of patients undergoing cesarean delivery under general anesthesia 2006 2007 2008 2009 2010 2011 2012 2013 Total † Total GA number 117 116 87 96 78 66 63 72 695 Intubated on first attempt Direct laryngoscopy 113 106 79 87 72 59 57 64 637 Glidescope 0 0 0 0 0 1¶ 2¶ 0 3 C-MAC 0 0 0 0 0 0 0 7¶ 7 Awake-fiberoptic 1 1 2 1 1 0 1 0 7 Intubated on second attempt* 3 7 5 8 5 6 3 1 38 Rescue LMA 0 2 1 0 0 0 0 0 3 GA: general anesthesia; LMA: laryngeal mask airway *Either with a different laryngoscope or by a senior person † Two patients were intubated secondary to trauma and information on attempts at direct laryngoscopy was not available ¶ Glidescope/C MAC videolaryngoscope used without attempts at direct laryngoscopy
14 Table 4 Characteristics of 10 patients requiring awake-intubation or having failed airway Age BMI ASA Preeclampsia Pre-existing maternal Emergent Mallampati (years) (kg/m2) status or eclampsia conditions CD score 19 36.4 3 Noonan syndrome + IV 38
30.8
3
+
26
37.8
2
28
29.2
25
Mouth opening (cm) 2-3
Sho nec +
-
IV
2-3
+
-
DM, severe burn contractures -
-
II
>3
+
3
+
nephrotic syndrome
+
II
NA
-
29.7
1
-
+
III
>3
+
23
26.5
2
-
-
IV
2
-
35
42.0
3
-
-
III
>3
-
26
31.2
1
-
twin pregnancy, placenta accreta severe rheumatioid arthritis, bamboo spine placenta previa thrombocytopenia -
+
NA
NA
-
34
31.0
2
-
-
+
III
2-3
-
22
38.7
2
-
-
-
III
>3
-
BMI: body mass index; ASA: American Society of Anesthesiology; CD: cesarean delivery; NA: not available; DL: direct lary DM: diabetes mellitus;
15 IJOA 16-00165 Highlights
The incidence of general anesthesia for cesarean deliveries was approximately 7%
Emergent cesarean delivery (57.8%) accounted for majority of the cases
97% of women were successfully intubated at direct laryngoscopy
The incidence of failed intubation was 1:232 and all were rescued by the LMA
S0959-289X(16)30102-9 http://dx.doi.org/10.1016/j.ijoa.2016.10.007 YIJOA 2507
To appear in:
International Journal of Obstetric Anesthesia
Received Date: Revised Date: Accepted Date:
17 July 2016 29 September 2016 20 October 2016
Please cite this article as: Rajagopalan, S., Suresh, M., Clark, S.L., Serratos, B., Chandrasekhar, S., Airway Management for Cesarean Delivery Performed Under General Anesthesia, International Journal of Obstetric Anesthesia (2016), doi: http://dx.doi.org/10.1016/j.ijoa.2016.10.007
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
IJOA 16-00165 ORIGINAL ARTICLE Airway management for cesarean delivery performed under general anesthesia S. Rajagopalan,a M. Suresh,a S. L. Clark,b B. Serratos,a S. Chandrasekhar a a
Department of Anesthesiology, Baylor College of Medicine, Houston, Texas, USA
b
Department of Obstetrics and Gynecology, Maternal Fetal Medicine, Baylor College of Medicine
Houston, Texas, USA
Short title: Airway management for cesarean delivery
Correspondence to: Suman Rajagopalan MD, Department of Anesthesiology, Baylor College of Medicine, One Baylor Plaza, MS: BCM-120, Houston, Texas 77030 E-mail address: [email protected]
2
ABSTRACT Background: With the increasing popularity of neuraxial anesthesia, there has been a decline in the use of general anesthesia for cesarean delivery. We sought to examine the incidence, outcome and characteristics associated with a failed airway in patients undergoing cesarean delivery under general anesthesia. Methods: A retrospective review of airway management in women undergoing cesarean delivery under general anesthesia over an eight-year period from 2006–2013 at an academic medical center was conducted. Results: During the study period, 10 077 cesarean deliveries were performed. Neuraxial anesthesia was used in 9382 (93%) women while general anesthesia was used in 695 (7%). Emergent cesarean delivery was the most common indication for general anesthesia. Failed intubation was encountered in only three (0.4%) women, who were successfully managed with a laryngeal mask airway. The overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666) and general anesthesia was continued in all cases. There were no adverse maternal or fetal outcomes directly related to failed intubation. Conclusion: Advances in adjunct airway equipment, availability of experienced anesthesiologist and simulation-based teaching of failed airway management in obstetrics may have contributed to our improved maternal outcomes in patients undergoing cesarean delivery under general anesthesia.
Keywords: Cesarean delivery; General anesthesia; Failed intubation
Introduction Difficulty in airway management and its associated risk of aspiration, maternal and fetal hypoxia are major causes of general anesthesia (GA)-related morbidity and mortality in patients undergoing cesarean delivery (CD).1,2 In the USA, anesthesia-related maternal mortality is estimated to be 0.12 per 100 000 live births.3 The incidence of failed tracheal intubation in pregnant women has been estimated to be five-to-seven-fold higher as compared to the non-pregnant population.4-7 In the last two decades, the use of GA for CD has decreased significantly and neuraxial techniques have become the preferred method.8 With the decline in the use of GA in pregnant women, there is concern that training in airway management in this population may be suboptimal.9,10 This could lead to an increased incidence of failed intubation, and associated maternal/fetal morbidity or mortality.
3
Importantly, this may impact on the anesthetic management in healthcare settings where providers of varying levels of experience and training provide anesthesia services. In this study, we sought to review indications for GA in CD and any associated airway complications in our academic center.
Methods This study was conducted under a research protocol approved by the Institutional Review Board of Baylor College of Medicine (BCM), Houston, TX and Harris Health System, Houston, TX. Ben Taub General Hospital, the primary academic teaching hospital of BCM, maintains a database on all CDs performed including the type of anesthesia. From this database, we identified all individuals who underwent CD under GA from January 2006 to December 2013. From the electronic medical records, information regarding history of pre-existing or pregnancy-related disorders, height, weight, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, indication for GA, preoperative Mallampati classification, neck movements, airway management techniques including number of attempts at laryngoscopy, Cormack and Lehane laryngoscopic score and complications related to airway management were collected. Failed tracheal intubation is typically defined as the inability to place a tracheal tube after multiple attempts.11 Although, there is no standard definition of failed intubation in obstetrics, it has generally been defined as failure to achieve tracheal intubation with a single dose of succinylcholine.4,5 It has also been described as unsuccessful attempts at placement of a tracheal tube using either direct laryngoscopy or alternative intubating equipment, the need to proceed with surgery with a non-elective unsecured airway or the need to abort intubation or surgery and awaken the woman before surgery.7,12 For the analysis of our data we used the definition “inability to secure the airway after a single dose of succinylcholine and no more than two attempts at intubation using conventional laryngoscope or an alternative airway device”.13
Results From 2006 to 2013, a total of 38 251 deliveries were performed of which 10 077 (26.3%) were CD (Table 1). Neuraxial anesthesia was employed in 9382 patients (93%) whereas GA was used in 695 (7%). Indications for GA are summarized in Table 2. Emergent CDs performed due to fetal indications (non-reassuring fetal status, fetal bradycardia, cord prolapse, and prolapse of fetal limbs)
4
or maternal causes (placenta previa, placental abruption, eclampsia, previous uterine surgery, trauma, and uterine rupture) accounted for the majority of cases performed under GA (n=402, 57.8%). This result was fairly consistent over the duration of the study. Limitation of time to perform neuraxial techniques in the emergent situation was the primary reason for choosing GA in these individuals. Failed neuraxial block was the second most common reason (n=160, 23%) for CD being performed under GA. The overall failure rate of neuraxial block was 1.7% (160 out of 9542). General anesthesia was electively performed in 17.5% of patients due to refusal of a neuraxial technique, presence of placenta accreta, increta or percreta, spinal abnormalities or coagulopathy. In 11 (1.5%) patients, neuraxial anesthesia was converted to GA intraoperatively, secondary to surgical complications that required securing the airway for prolonged surgery. Most patients (n=673; 96.8%) were successfully intubated by direct laryngoscopy and were not considered a difficult intubation. Nearly 94% were intubated on the first attempt, while a second attempt by a more experienced person, or the use of a different laryngoscopic blade was required in 38 (5.6%) patients (Table 3). An Eschmann’s gum elastic bougie was successfully used in three patients during the first or the second attempt at intubation. Since intubation was successful with the bougie in the first two attempts, these patients did not meet the criteria for failed intubation. In 10 patients, a videolaryngoscope was used (Glidescope n=3, C-MAC n=7) as an alternative to direct laryngoscopy as the intubation was predicted to be difficult. Elective awake-fiberoptic intubation was performed in seven patients (1%) with an anticipated difficult airway. Most patients requiring awake-fiberoptic intubation had a non-reassuring airway exam with Mallampati scores of >III, a short, thick neck, or restricted neck movement (Table 4). There were three cases of failed tracheal intubation before 2010 (0.43%); all were successfully rescued with a laryngeal mask airway (LMA). In two patients, a tracheal tube was successfully placed through a Fastrach Intubating LMA while in the third patient oxygenation was maintained through the LMA. General anesthesia was chosen in two of the patients with failed intubation due to the emergent nature of the CD while a failed neuraxial technique was the reason in the third. All three patients had higher Mallampati scores but good mouth opening and full neck movements. Hence, a preoperative exam did not predict difficulty with intubation. None of these patients showed evidence of aspiration of gastric contents and were successfully extubated at the end
5
of surgery. There were no cases requiring a surgical airway or maternal mortality from GA for CD during the study period.
Discussion In this study, over a period of eight years the overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666). Studies that have evaluated the incidence of failed intubation during the same study period have reported similar results.14-16 A systematic review of 27 studies that collectively included over 88 000 individuals revealed that the incidence of failed tracheal intubation was 1 in 443 and that this was relatively unchanged over the years.7 Our facility represents a large center consisting of providers with varying levels of training who care for a diverse population of patients. Results from retrospective analyses of large datasets from an unselected patient population in such settings are likely to be applicable to clinical practice. The proportion of CDs in our cohort (26%) was lower than the national average of 33% reported by the Centers for Disease Control and Prevention (CDC) in 2013.17 The incidence of GA for CD was approximately 7%. As expected, the majority of cases performed under GA were for emergency CD. The second most common reason was failed neuraxial technique, which contributed to approximately one quarter of cases. About 97% of the patients were intubated by direct laryngoscopy either at the first or second attempt. As our facility is a teaching hospital, an anesthesia resident or a student nurse anesthetist are typically the first to attempt intubation. Senior residents or attending anesthesiologists take over if the initial attempt is unsuccessful. Complications related to anesthesia rank tenth among the causes of pregnancy-related deaths in the USA.18 Airway-related complications associated with failed intubation and the inability to ventilate or oxygenate following induction of GA are major causes for anesthesia-related mortality.3 The anatomic and physiologic changes during pregnancy place the parturient at higher risk for desaturation, difficult mask ventilation and failed intubation. In addition, these changes predispose to a higher risk of aspiration of gastric contents during induction or immediately following extubation. In recent years, awareness of airway-related complications has prompted an increase in the use of neuraxial techniques. In the USA the incidence of GA for CD has declined and has been reported to be between 0.5% and 7%.19-21 It is likely that medicolegal factors also influence the decision to use GA. The American Society of Anesthesiology (ASA) Closed Claims Analysis (1990–2003) in Obstetric Anesthesia reported that claims for maternal death and permanent brain damage were
6
higher for difficult intubation (25%) and maternal hemorrhage (29%) following GA for CD.22 Thus, use of GA is currently limited to emergent CD in situations when a neuraxial technique is contraindicated or in patients who refuse neuraxial anesthesia. An immediate clinical consequence of failed intubation that needs to be addressed is whether to continue with GA. Some studies have reported a high percentage of patients with failed intubation who were awakened from anesthesia.4,23,24 In our cohort, we successfully used an LMA as a rescue device in all three patients with a failed intubation and where GA was continued. The widespread availability of videolaryngoscopes and LMAs as rescue devices has improved airway management and is likely to result in continuation of GA in most patients with a failed intubation. The ASA algorithm for difficult obstetric airway management has incorporated the LMA as the rescue device in cannot intubate and cannot oxygenate situations. Although the LMA does not prevent the risk of aspiration, it is proven to be a valuable rescue device in maintaining ventilation and oxygenation in difficult airway situations.14,15,25,26 The ASA Closed Claim Analysis noted that use of LMA as a rescue device for unanticipated difficult airway has resulted in a decrease in the incidence of brain death and mortality.22 Another device that has become a first-line rescue for failed intubation is the video laryngoscope. It is interesting to note that during our study period, we had no cases of failed intubation after 2010, the time at which we added videolaryngoscopes to our difficult airway cart. Videolaryngoscopes provide an excellent view of the glottis and vocal cords and increase the success rate in unanticipated difficult intubation. The success rate of intubation on first attempt with the CMAC has been shown to be higher when compared to direct laryngoscopy in patients with a predicted difficult airway.27,28 Although there are no published studies clearly demonstrating the effectiveness of videolaryngoscopes as a rescue device in the obstetric population, it has been utilized to secure the airway in patients where conventional direct laryngoscopy was unsuccessful.29,30 There has been a decline in maternal mortality related to GA in recent years. Hawkins et al. demonstrated that anesthesia-related maternal mortality during CD decreased from 16.8 deaths per million GAs between 1991 and 1995 to 6.5 deaths per million GAs between 1997 and 2002.3 This decline could be attributed to heightened awareness of failed intubation, utilization of a difficult airway algorithm and early use of advanced airway devices.13,31 Our study, and others conducted over the last eight years, reported no maternal deaths related to GA in spite of instances of failed intubation.10,14-16
7
At our institution, we have adopted several measures to improve the maternal outcomes for CD performed under GA. Firstly, a faculty anesthesiologist is immediately available in the labor and delivery suite for round-the-clock supervision of trainees. Secondly, we have made sure that airway adjunct equipment like the LMA, videolaryngoscope and fiberoptic scope is readily available. Finally, we have formally incorporated didactic simulation scenarios pertaining to the difficult obstetric airway in the teaching curriculum for trainees. Use of simulation training has been endorsed by the UK Confidential Enquiries into Maternal Deaths 2003–2005 and 2006–2008 to improve performance in the management of emergencies.32,33 With the decline in experience of GA for CD, simulating the scenario followed by debriefing is an alternate way of improving skills.34 The results from analyses in this study have to be interpreted in the context of limitations of the dataset. All data points were collected from a retrospective review of medical records. As with any retrospective study, data collection was not performed in a standardized manner. Thus, it is possible that physicians graded Mallampati scores, neck movements, and Cormack-Lehane laryngoscopic scores differently. Practice preferences of physicians may have influenced employment of videolaryngoscope as the initial method of choice for intubation, which may have underestimated the incidence of failed intubations. Finally, the event rate of failed intubation was low; precluding statistical analyses that could identify potential correlates associated with failed intubation. In conclusion, our results add to the growing body of literature that demonstrates that in spite of the relatively stable rates of failed intubation over the years, maternal mortality with GA is declining. Enhanced awareness of the ASA difficult airway algorithm, availability of newer airway devices, presence of an experienced anesthesia provider, improvement in skills and simulation training of failed airway in obstetrics have resulted in continuation of GA in most cases of failed intubation without adverse maternal outcomes.
Disclosure This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. None of the authors have any conflicts
References 1.
Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse respiratory event in anesthesia: a closed claims analysis. Anesthesiology 1990; 72:828-33.
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Ezri T, Szmuk P, Evron S, Geva D, Haqay Z, Katz J. Difficult airway in obstetric anesthesia: a review. Obstet Gynecol Surv 2001; 56:631-41.
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Hawkins JL, Chang J, Palmer SK, Gibbs CP, Callaghan WM. Anesthesia-related maternal mortality in the United States: 1979 -2002. Obstet Gynecol 2011; 117:69-74.
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Hawthorne L, Wilson R, Lyons G, Dresner M. Failed intubations revisited: 17-yr experience in a teaching maternity unit. Br J Anaesth 1996; 76:680-684.
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Barnardo PD, Jenkins JG. Failed tracheal intubation in obstetrics: a 6-year review in a UK region. Anaesthesia. 2000; 55:690-4.
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Rahman K, Jenkins JG. Failed tracheal intubation in Obstetrics: no more frequent but still managed badly. Anaesthesia 2005; 60:168-71.
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Kinsella SM, Winton AL, Mushambi MC, et al. Failed tracheal intubation during obstetric general anaesthesia: a literature review. Int J Obstet Anesth 2015; 24:356-74.
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Bowring J, Fraser N, Vause S, Heazell AE. Is regional anaesthesia better than general anaesthesia for caesarean section? J Obstet Gynaecol 2006; 26:433-4.
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Johnson RJ, Lyons GR, Wilson RC, Robinson RPC. Training in Obstetric general anesthesia; a vanishing art? Anaesthesia 2000; 55:179-83.
10. Djabatey EA, Barclay PM. Difficult and failed intubation in 3430 obstetric general anesthetics. Anaesthesia 2009; 64:116. 11. Apfelbaum JL, Hagberg CA, Caplan RA, et al; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013; 118:251-70. 12. McKeen DM, George RB, O’Connell CM, et al. Difficult and failed intubation: incident rates and maternal, obstetrical and anesthetic predictors. Can J Anesth 2011;58:514-24. 13. Suresh MS, Wali A, Crosby ET. Difficult and failed intubation: Strategies, prevention and management of airway-related catastrophes in obstetrical patients. In: Suresh M, Segal BS, Preston RL, Fernando R, Mason CL. Shnider and Levinson’s Anesthesia for obstetrics 5th edition; 2012. 363-402. 14. Tao W, Edwards JT, Tu F, Xie Y, Sharma SK. Incidence of unanticipated difficult airway in obstetric patients in a teaching institution. J Anesth 2012; 26:339-45. 15. Quinn AC, Milne D, Columb M, Gorton H, Knight M. Failed tracheal intubation in obstetric
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anaesthesia: 2 yr national case-control study in the UK. Br J Anaesth 2013; 110:74-80. 16. Nafisi S, Darabi ME, Rajabi M, Afshar M. General anesthesia in cesarean sections: a prospective review of 465 cesarean sections performed under general anesthesia. Middle East J Anaesthesiol 2014; 22:377-84. 17. Martin JA, Hamilton BE, Ventura SJ, Osterman MJ, Mathews TJ. Births: final data for 2011. Natl Vital Stat Rep 2013; 62:1-69. 18. Creanga AA, Berg CJ, Syverson C, Seed K, Bruce FC, Callaqhan WM. Pregnancy-related mortality in the United States, 2006-2010. Obstet Gynecol 2015; 125:5-12. 19. Palanisamy A, Mitani AA, Tsen LC. General anesthesia for cesarean delivery at a tertiary care hospital from 2000 to 2005: a retrospective analysis and 10-year update. Int J Obstet Anesth 2011; 20:10-6. 20. Tsen LC, Pitner R, Camann WR. General anesthesia for caesarean section at a tertiary care hospital 1990–1995: indications and implications. Int J Obstet Anesth 1998; 7:147-52. 21. Bloom SL1, Spong CY, Weiner SJ, et al. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Complications of anesthesia for cesarean delivery. Obstet Gynecol 2005; 106:281-287. 22. Davies JM, Posner KL, Lee LA, Cheney FW, Domino KB. Liability associated with obstetric anesthesia: a closed claims analysis. Anesthesiology 2009; 110:131-9. 23. Lyons G. Failed intubation. Six years’experience in a teaching maternity unit. Anaesthesia 1985; 40:759-62. 24. Shibli KU, Russell IF. A survey of anaesthetic techniques used for caesarean section in the UK in 1997. Int J Obstet Anesth 2000; 9:160-7. 25. Bailey SG, Kitching AJ. The laryngeal mask airway in failed obstetric tracheal intubation. Int J Obstet Anesth 2005; 14:270-1. 26. McDonnell NJ, Paech MJ, Clavisi OM, Scott KL. ANZCA trials group. Difficult and failed intubation in obstetric anaesthesia: an observational study of airway management and complications associated with general anaesthesia for caesarean section. Int J Obstet Anesth 2008; 17:292–97. 27. Aziz MF, Dillman D, Fu R, Brambrink AM. Comparative effectiveness of the C-MAC video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway. Anesthesiology 2012; 116:629-36.
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28. Sakles JC, Mosier J, Chiu S, Cosentino M, Kalin L. A comparison of the C-MAC videolaryngoscope to the Macintosh direct laryngoscope for intubation in the emergency department. Ann Emerg Med 2012; 60:739-48. 29. Piepho T, Fortmueller K, Heid FM, Schmidtmann I, Werner C, Noppens RR. Performance of the C-MAC video laryngoscope in patients after a limited glottic view using Macintosh laryngoscopy. Anaesthesia 2011; 66:1101-5. 30. Kilicaslan A, Topal A, Tavian A, Erol A, Otelcioglu S. Effectiveness of the C-MAC video laryngoscope in the management of unexpected failed intubations. Braz J Anesthesiol 2014; 64:62-65. 31. Mushambi MD, Kinsella SM, Popat M, et al. Obstetric Anaesthetists’ Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics. Anaesthesia 2015; 70:1286-306. 32. Confidential Enquiries into Maternal and Child Health (CEMACH) Saving Mother’s Lives: Reviewing maternal deaths to make motherhood safer: 2003-2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. London. CEMACH. 33. Centre for Maternal and Child Enquiries (CMACE). Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer: 2006–08. The Eighth Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. BJOG 2011;118(Suppl. 1):1–203. 34. Balki M, Chakravarty S, Salman A, Wax RS. Effectiveness of using high-fidelity simulation to teach the management of general anesthesia for Cesarean delivery. Can J Anaesth 2014; 61:92234.
11 Table 1 Number of cesarean deliveries under general anesthesia 2006 2007 2008 2009 Total deliveries 6372 5788 5417 5368 Cesarean deliveries 1608 1495 1431 1390 (25.2%) (25.8%) (26.4%) (25.9%) Cesarean deliveries 117 116 87 96 under GA (7.27%) (7.76%) (6.08%) (6.91%) Data are number (%)
2010 4305 1150 (26.7%) 78 (6.67%)
2011 3671 1117 (30.4%) 66 (5.91%)
2012 3744 964 (25.7%) 63 (6.5%)
2013 3586 922 (25.8%) 72 (7.8%)
Tot 38,2 10 0 (26.3 69 (6.89
12 Table 2 Indications for general anesthesia for cesarean delivery 2006 2007 2008 2009 2010 Total GA number 117 116 87 96 78 Elective 7 12 12 26 16 Failed neuraxial 17 29 23 24 20 block Intraoperative 0 0 0 2 4 conversion Emergency 93 75 52 44 38 GA: general anesthesia
2011 66 13 13
2012 63 21 12
2013 72 15 22
Total 695 122 (17.5%) 160 (23%)
1
2
2
11 (1.5%)
39
28
33
402 (57.8%)
13 Table 3 Airway management of patients undergoing cesarean delivery under general anesthesia 2006 2007 2008 2009 2010 2011 2012 2013 Total † Total GA number 117 116 87 96 78 66 63 72 695 Intubated on first attempt Direct laryngoscopy 113 106 79 87 72 59 57 64 637 Glidescope 0 0 0 0 0 1¶ 2¶ 0 3 C-MAC 0 0 0 0 0 0 0 7¶ 7 Awake-fiberoptic 1 1 2 1 1 0 1 0 7 Intubated on second attempt* 3 7 5 8 5 6 3 1 38 Rescue LMA 0 2 1 0 0 0 0 0 3 GA: general anesthesia; LMA: laryngeal mask airway *Either with a different laryngoscope or by a senior person † Two patients were intubated secondary to trauma and information on attempts at direct laryngoscopy was not available ¶ Glidescope/C MAC videolaryngoscope used without attempts at direct laryngoscopy
14 Table 4 Characteristics of 10 patients requiring awake-intubation or having failed airway Age BMI ASA Preeclampsia Pre-existing maternal Emergent Mallampati (years) (kg/m2) status or eclampsia conditions CD score 19 36.4 3 Noonan syndrome + IV 38
30.8
3
+
26
37.8
2
28
29.2
25
Mouth opening (cm) 2-3
Sho nec +
-
IV
2-3
+
-
DM, severe burn contractures -
-
II
>3
+
3
+
nephrotic syndrome
+
II
NA
-
29.7
1
-
+
III
>3
+
23
26.5
2
-
-
IV
2
-
35
42.0
3
-
-
III
>3
-
26
31.2
1
-
twin pregnancy, placenta accreta severe rheumatioid arthritis, bamboo spine placenta previa thrombocytopenia -
+
NA
NA
-
34
31.0
2
-
-
+
III
2-3
-
22
38.7
2
-
-
-
III
>3
-
BMI: body mass index; ASA: American Society of Anesthesiology; CD: cesarean delivery; NA: not available; DL: direct lary DM: diabetes mellitus;
15 IJOA 16-00165 Highlights
The incidence of general anesthesia for cesarean deliveries was approximately 7%
Emergent cesarean delivery (57.8%) accounted for majority of the cases
97% of women were successfully intubated at direct laryngoscopy
The incidence of failed intubation was 1:232 and all were rescued by the LMA