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A Retrospective Study of the Performance of Video Laryngoscopy in an Obstetric Unit

Aziz, Michael F. MD; Kim, Diana MD; Mako, Jeffrey MD; Hand, Karen MD, FRCA; Brambrink, Ansgar M. MD, PhD

doi: 10.1213/ANE.0b013e3182642130
Obstetric Anesthesiology: Brief Report

We evaluated the performance of tracheal intubation using video laryngoscopy in an obstetric unit. We analyzed airway management details during a 3-year period, and observed 180 intubations. All cases were managed with direct or video laryngoscopy. Direct laryngoscopy resulted in 157 out of 163 (95% confidence interval [CI], 92%–99%) first attempt successful intubations and failed once. Video laryngoscopy resulted in 18 of 18 (95% CI, 81%–100%) successful intubations on first attempt. The failed direct laryngoscopy was rescued with video laryngoscopy. The patients managed with video laryngoscopy frequently required urgent or emergency surgery and had predictors of difficult direct laryngoscopy in 16 of 18 cases. Video laryngoscopy may be a useful adjunct for obstetric airway management, and its role in this difficult airway scenario should be further studied.

Published ahead of print July 4, 2012 Supplemental Digital Content is available in the text.

From the Department of Anesthesiology & Perioperative Medicine, Oregon Health & Science University, Portland, OR.

Funding: Internally funded.

Conflicts of Interest: See Disclosures at the end of the article.

Reprints will not be available from the authors.

This report was previously presented, in part, at the American Society of Anesthesiologists Annual Meeting Chicago, IL, October 2011.

Address correspondence to Michael Aziz, MD, Department of Anesthesiology & Perioperative Medicine, Oregon Health & Science University, Mail Code KPV 5, 3181 SW Sam Jackson Park Rd., Portland, OR 97239. Address e-mail to azizm@ohsu.edu.

Accepted May 15, 2012

Published ahead of print July 4, 2012

The peripartum patient is at increased risk for failed airway management.1 3 In cases of difficult intubation, guidelines provide recommendations for the availability of advanced airway equipment, and neuraxial anesthesia is encouraged.4 Furthermore, these guidelines suggest resource availability of flexible fiberoptic laryngoscopes. Video laryngoscopy has been used to manage the difficult airway in the operating room, and its use has been reported in cases of difficult intubation in the labor and delivery setting.5 8 We aimed to determine the performance and provider selection of video laryngoscopy among obstetric patients undergoing general endotracheal anesthesia in a delivery suite of a large tertiary care academic center in a retrospective study. We hypothesized that video laryngoscopy results in a high intubation success rate even in patients with anticipated difficult airway and that it can be used to rescue failed direct laryngoscopy.

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METHODS

IRB permission was obtained to query anesthetic records contained within a perioperative data warehouse; individual written informed patient consent was waived to evaluate this database. For each anesthetic, a detailed anesthesia history and physical examination were documented by an anesthesiology resident or anesthesiology attending physician using a point-of-care perioperative clinical information system (Centricity™, General Electric Healthcare, Waukesha, WI). Records were reviewed from procedures performed in a single labor and delivery unit at Oregon Health & Sciences University (Portland, OR) during a 36-month period. Airway management details were reviewed from all records in which tracheal intubation was attempted and documented in the electronic record. These records were further queried to determine patient anthropometric data and airway management details from discreet data elements, including age, height, weight, body mass index, airway physical examination findings, status of last oral intake, surgical procedure, laryngoscopy devices used, number of attempts, intubation-related trauma, and providers performing the anesthetic. These records were then further reviewed manually for free text data to determine the reason for performance of general anesthesia, the surgical indication and urgency, and description of any airway-related trauma. The nature of the surgical emergency was further categorized for the video laryngoscopy group according to a defined classification group as emergency, urgent, scheduled, or elective.9 Data were compiled, and missing information is reported. For the entire study period, direct laryngoscopy tools, supraglottic airways, and a dedicated flexible fiberoptic laryngoscope were available in the delivery suite. A Glidescope® (Verathon, Bothell, WA) video laryngoscope was used and available throughout the initial study period and stored in the general operating rooms 6 floors away in the same hospital, and a dedicated device became available for the last 15 months of the study period.

Statistical analysis was conducted using Stata® (StataCorp Statistical Software: release 12, College Station, TX). The patient history and examination details as well as intubation details were summarized using descriptive statistics and compared between parturients whose tracheas were intubated with direct laryngoscopy and video laryngoscopy. These variables included patient age, body mass index, Mallampati classification score, thyromental distance, mouth opening, neck anatomy, status of last oral intake, level of urgency, operation performed, and Cormack–Lehane laryngeal view achieved. Categorical variables were compared using a χ2 test or Fisher exact test as appropriate. Continuous variables were compared using 2-tailed Student t test based upon equal variance. Confidence intervals regarding intubation success were calculated using the Clopper–Pearson method. Significance was deemed at P < 0.05.

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RESULTS

Video laryngoscopy resulted in 18 out of 18 (95% confidence interval [CI], 81%–100%) first attempt successful intubations. Direct laryngoscopy resulted in successful intubation in 157 of 163 intubations on first attempt (95% CI, 92%–99%), 5 times with up to 3 attempts, and it failed once. All tracheas were successfully intubated by direct or video laryngoscopy. Details regarding relative airway predictors, level of urgency, and intubation conditions for both laryngoscopy groups are summarized in Table 1, and further description of the sample is provided below.

Table 1

Table 1

Airway management details were analyzed among 6742 deliveries from June 11, 2008, to May 18, 2011. Among these deliveries, 2009 occurred by cesarean (30%). General endotracheal anesthesia was performed in 180 cases. Seven percent (133 of 2009) of the cesarean deliveries were managed with general endotracheal anesthesia. An additional 47 women required general endotracheal anesthesia for immediate postpartum surgical procedures. The intubations were performed by 56 anesthesiology residents at the postgraduate year 2 to 5 with a minimum of 5 months clinical anesthesiology experience in the operating room. These residents were immediately supervised by attending anesthesiologists who guided the intubation and assisted when appropriate. Four attending anesthesiologists provided solo care.

Rapid sequence induction was performed in 166 of 180 cases (92%). Neuromuscular blockade was used to facilitate intubation in 169 of 180 cases (94%). No awake intubations were attempted. Bag-mask ventilation was attempted in 14 cases and considered easy in 11 cases and difficult in 1 case; 2 patients could not be mask ventilated.

The general operating room–based video laryngoscope was used during 5 of 96 intubations before a dedicated unit became available, and during 13 of 84 intubations afterward. Direct laryngoscopy was performed with Macintosh size 3 and 4, and Miller size 2 and 3 blades. The one failure of direct laryngoscopy was successfully managed with an immediately available video laryngoscope. A gum-elastic bougie was used to facilitate intubation in 2 of the direct laryngoscopies. No other airway management tools were used in this series. Specifically, a supraglottic airway, flexible fiberoptic laryngoscope, and surgical airway were not used during attempted tracheal intubation.

Six of the 18 patients intubated with the video laryngoscope had emergency surgery, and 10 had urgent surgery. In 16 of 18 cases, the following predictors of difficult direct laryngoscopy were identified: Mallampati scale score III or IV, body mass index >35 kg/m2, mouth opening <3 cm, or thyromental distance <6 cm. There was no documentation of aspiration, pharyngeal injury, or tracheal injury in the anesthetic record in any patient.

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DISCUSSION

To our knowledge, this report summarizes the largest analysis of the performance of video laryngoscopy in a labor and delivery unit. Video laryngoscopy was successful on first attempt with a favorable laryngeal view in all cases, even in a patient population predicted to be more difficult to intubate. Interestingly, all airways were successfully managed with direct or video laryngoscopy during this 3-year period. Rescue of failed direct laryngoscopy with video laryngoscopy in the parturient has been described previously.6 8 The labor and delivery unit presents a very unique and concerning environment for airway management, because the delivery suite is often remote from the main operating rooms, procedures can be emergent, patients may not be fasted, and airway intubations are at a higher risk for failure. Video laryngoscopy was used primarily in patients with additional predictors of difficult direct laryngoscopy beyond the risk of pregnancy and emergency surgery. It appears that the majority of airways in an obstetric unit can be managed with direct laryngoscopy and or video laryngoscopy. Our data showed that laryngoscopists frequently achieved an adequate laryngeal view in both groups. The data may reflect good practice around optimization of neuraxial anesthesia and appropriate selection of video laryngoscopy in patients who may be more difficult to intubate. This study is limited because the incidence of failed intubation was not large enough to draw conclusions about whether video laryngoscopy improves outcomes. However, with a reported incidence of failed airway management occurring in 1:250 cases,10 the low rate of general anesthesia for obstetric anesthesia, and the emergency nature of the surgical procedure, such a study will be difficult to conduct. In conclusion, failed airway management remains a feared risk of obstetric airway management, and video laryngoscopy should be further studied to determine if that risk can be reduced.

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DISCLOSURES

Name: Michael F. Aziz, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Michael Aziz has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.

Conflicts of Interest: Michael Aziz received research funding from Karl Storz Endoscopy, a competing vendor.

Name: Diana Kim, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Diana Kim has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflict of interest to declare.

Name: Jeffrey Mako, MD.

Contribution: This author helped analyze the data.

Attestation: Jeffrey Mako has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflict of interest to declare.

Name: Karen Hand, MD, FRCA.

Contribution: This author helped design the study and write the manuscript.

Attestation: Karen Hand has seen the original study data and approved the final manuscript.

Conflicts of Interest: The author has no conflict of interest to declare.

Name: Ansgar M. Brambrink, MD, PhD.

Contribution: This author helped design the study, conduct the study, and write the manuscript.

Attestation: Ansgar Brambrink has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: Ansgar Brambrink received research funding from Karl Storz Endoscopy, a competing vendor.

This manuscript was handled by: Cynthia A. Wong, MD.

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REFERENCES

1. Hawthorne L, Wilson R, Lyons G, Dresner M. Failed intubation revisited: 17-yr experience in a teaching maternity unit. Br J Anaesth 1996;76:680–4
2. Lyons G. Failed intubation. Six years' experience in a teaching maternity unit. Anaesthesia 1985;40:759–62
3. Tsen LC, Pitner R, Camann WR. General anesthesia for cesarean section at a tertiary care hospital 1990–1995: indications and implications. Int J Obstet Anesth 1998;7:147–52
4. American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology 2007;106:843–63
5. Aziz MF, Healy D, Kheterpal S, Fu RF, Dillman D, Brambrink AM. Routine clinical practice effectiveness of the Glidescope in difficult airway management: an analysis of 2,004 Glidescope intubations, complications, and failures from two institutions. Anesthesiology 2011;114:34–41
6. Turkstra TP, Armstrong PM, Jones PM, Quach T. GlideScope use in the obstetric patient. Int J Obstet Anesth 2010;19:123–4
7. Browning RM, Rucklidge MW. Tracheal intubation using the Pentax Airway Scope videolaryngoscope following failed direct laryngoscopy in a morbidly obese parturient. Int J Obstet Anesth 2011;20:200–1
8. Dhonneur G, Ndoko S, Amathieu R, Housseini LE, Poncelet C, Tual L. Tracheal intubation using the Airtraq in morbid obese patients undergoing emergency cesarean delivery. Anesthesiology 2007;106:629–30
9. Lucas DN, Yentis SM, Kinsella SM, Holdcroft A, May AE, Wee M, Robinson PN. Urgency of caesarean section: a new classification. J R Soc Med 2000;93:346–50
10. McKeen DM, George RB, O'Connell CM, Allen VM, Yazer M, Wilson M, Phu TC. Difficult and failed intubation: incident rates and maternal, obstetrical, and anesthetic predictors. Can J Anaesth 2011;58:514–24
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