Direct laryngoscopy performed using traditional Macintosh and Miller blades is currently the standard of care for performing tracheal intubation. Video laryngoscopes (VLs) have been shown to improve glottic exposure and increase first-attempt success rates for tracheal intubation in both elective operating room (OR) and simulation-based settings when compared with the direct laryngoscope (DL).1–4 Emergency airway management in critically ill patients outside the controlled setting of the OR is associated with a higher incidence of difficult intubations, ranging anywhere from 10% to 22%, and also with increased risk of respiratory and hemodynamic complications, including death.5–9 The usefulness of the VL for urgent endotracheal intubations (UEIs) in critically ill patients outside the OR has not been well studied. Video laryngoscopy has recently been shown to improve glottic views and intubation success rates in the emergency department (ED) and prehospital setting and specifically in patients with known difficult airway predictors.10–15
Our training program for Pulmonary and Critical Care Medicine (PCCM) fellows traditionally focused teaching on the DL as the primary intubation device until 2010 when we began instruction using the VL as the primary device based on the OR and simulation literature.1–4 Data were collected as part of standard quality improvement regarding the effectiveness of intubations during the entire study period.
We assessed the effectiveness of using a VL as the primary intubating device during UEI performed by PCCM fellows in critically ill patients. The primary measured outcome was first-attempt intubation success rate. Secondary outcomes included total number of attempts required for successful tracheal intubation, rate of esophageal intubation, need for supervising attending intervention, duration of the intubation sequence, and incidence of hypoxemia and hypotension. We hypothesized that intubation using a VL was superior to that of a DL with regard to first-attempt success rate and the total number of attempts required for successful tracheal intubation when UEI was performed by less experienced operators such as PCCM fellows. Our prospectively collected intubation quality improvement data were further analyzed retrospectively to test this hypothesis in a similar cohort of PCCM fellows.
The study was in compliance with Anesthesia & Analgesia’s requirements for the responsible conduct of research.
The study was performed at Beth Israel Medical Center in New York City, NY, an 800-bed teaching hospital with a 16-bed closed medical intensive care unit (MICU) that is staffed by full-time pulmonary and critical care attendings. The fellowship program has 9 PCCM fellows who rotate through the MICU. PCCM fellows function as team leaders for urgent intubations in the MICU and on the hospital wards under the supervision of attending physicians. This study was approved by the Committee of Scientific Affairs of Beth Israel Medical Center, which waived requirement for informed consent (IRB no. 048-07).
Standardization of Intubation Sequence
All PCCM fellows received standardized training in the performance of UEI in the first month of their fellowship as previously described by our group.16 In summary, first-year fellows attended a series of 15 mandatory training sessions of approximately 1.5 hours duration and received specific training in team leadership skills in UEI. The sessions included training in crew resource management, combined team organization, deliberate practice in tracheal intubation technique using task trainers, and mastery of a mandatory 42-point checklist required for safe UEI.16 The fellows were trained in a replicated work environment using a computerized patient simulator (SimMan®, Laerdal Medical, Laerdal, Norway). They were required to repeatedly practice their skills as team leaders for UEI in multiple scenarios of increasing complexity such that, at the end of the training sessions, the fellows were required to demonstrate perfect adherence with all 42 points on the checklist during the simulated scenarios before they were allowed to perform tracheal intubations. If perfect adherence was not demonstrated, the scenario was repeated until the fellow could execute all 42 points in sequence during the simulation exercise. Although fellows did have the option of completing an elective anesthesiology airway management rotation in the OR, no fellows in either study group participated in this rotation. Once trained, the fellows were assigned as first responders and team leaders for all UEIs during their rotations, covering medical emergencies on the medical wards as well as in the MICU. Team leader responsibilities included the physical performance of tracheal intubation.
This was a retrospective cohort study comparing UEIs performed by PCCM fellows during identical 3-month time periods (April through June) of 2 different years. Data were collected prospectively during both time periods and placed in a deidentified database for purposes of quality assessment of UEI.
Identical calendar months of 2 different years (2006 and 2010) were chosen to compare the 2 PCCM fellow cohorts to ensure identical experience level of the fellows performing UEI. The final quarter of the academic year was chosen for study, so that all fellows, particularly first-year fellows, had undergone simulation training, were well-versed with the standardized checklist for intubation, and had adequate experience as team leaders for UEI. This quarter also allowed for uniformity among all the PCCM fellows and between the 2 cohorts. The first data cohort period occurred from April through June 2006 (DL period), in the first year after the introduction of the simulation training program that used combined teams, standardized checklist approach for intubation described earlier whereby all training and all UEIs were performed with a DL (Rüsch Standard Laryngoscope, Macintosh or Miller blades number 3 or 4, Teleflex Medical, Research Triangle Park, NC) as the primary intubating device.16
The second cohort was obtained from the period after the adoption of the VL (GlideScope® GVL®, or GlideScope® Ranger, Verathon, Bothell, WA) as the primary intubating device from April through June 2010 (VL period). In preparation for the VL period, all fellows received additional specific training in the use of the VL with repeated supervised deliberate practice on task trainers. All other team leader training was identical to the checklist-based instruction provided to fellows in cohort 1.
The standardized checklist approach for tracheal intubation and the medications for induction were similar in both groups. The American Society of Anesthesiologists'’ difficult airway algorithm was followed during both years.17 Neuromuscular blockade was not used routinely in critically ill patients as per divisional protocol. A PCCM or anesthesiology attending was available as backup for all intubations; however, they were not present for direct supervision during all intubations.
Data on the rates of first-attempt success, difficult intubations, inadvertent esophageal intubations, number of attempts required, and the duration of the intubation sequence were prospectively collected for all UEIs where the fellow was team leader. In addition, data on rates of attending intervention and complications were recorded.
An attempt was defined as the action of inserting a laryngoscope into the oropharynx. Each instance of laryngoscope removal and reinsertion was counted as a subsequent attempt whether by the original or a more senior operator. First-attempt success was noted when the trachea was intubated during the first insertion of the laryngoscope. An intubation was considered a difficult intubation when ≥3 attempts were required to successfully intubate the trachea or if there was an attending-level attempt. The duration of the intubation sequence was defined as the time from the administration of induction drugs to the confirmation of tube placement in the trachea. This included the time for oxygen administration and optimization of hemodynamics, which is emphasized in our protocol.16
Data collection methods during the 2 time periods were as follows:
During the DL period, data on UEI were derived from audio recordings made by the PCCM fellow during the UEI sequence as described previously.16 Hemodynamic and oxygenation data were collected from measurements recorded by MICU patient monitors. When monitoring was not available, nadir saturations and arterial blood pressures were obtained from interview with the team leader and review of the audio record.
During the VL period, data from UEI were collected in real time throughout the UEI sequence by a team member whose sole task was to report and record the information using a standardized written data collection tool. Patient demographic and comorbidity data were extracted from retrospective chart review for both cohorts.
Complications during UEI were defined as oxygen desaturation <80%, systolic blood pressure <70 mm Hg, esophageal intubation, difficult intubation (≥3 attempts including attending-level attempt), or death of the patient within 30 minutes of UEI.
Categoric variables are reported as counts and percentages. Baseline data were compared by t tests for continuous variables and by the χ2 test or Fisher exact test for categoric variables. Primary and secondary outcomes and complications were binary, and the χ2 test or Fisher exact test was used to compare outcomes and complications in the VL and DL groups. Data were analyzed using GraphPad Software InStat (GraphPad Software Inc., La Jolla, CA).
There were 138 UEIs performed by PCCM fellows during the 2 periods. In the DL period, 50 UEIs were performed using a DL and in the VL period, 78 UEIs were performed using a VL. Demographics and disease characteristics were similar between the 2 groups as shown in Table 1. In the DL period, first-year fellows performed 50% of the UEIs whereas in the VL period, they performed 60% of the UEIs (P < 0.01). In the DL period, second-year and third-year fellows performed 18% and 32% of UEIs, respectively, whereas in the VL period, they performed 33% and 6% of UEIs, respectively.
The rate of first-attempt success was superior with a VL as compared with a DL (91% vs 68%, P < 0.01). The rate of intubations requiring ≥3 was lower in the VL period (4% vs 20%, P < 0.01). The VL group required fewer attempts for successful tracheal intubation. There were no unintended esophageal intubations in the VL group compared with the DL group (0% vs 14%, P < 0.01). The average number of attempts required for successful tracheal intubation was also less in the VL group (1.2 ± 0.56 vs 1.7 ± 1.1, P < 0.01). Furthermore, the duration of the intubation sequence was shorter in the VL group, (3.9 ± 3 minutes vs 13.0 ± 6 minutes, P = 0.13), although this did not reach statistical significance (Table 2).
Our study showed higher success of tracheal intubation during UEI when a VL was used as the primary intubating device by PCCM fellows when compared with a DL. The rates of first-attempt success, difficult intubations (≥3 attempts), esophageal intubations, and the total number of attempts required for successful tracheal intubation all improved significantly with use of a VL. The majority of tracheal intubations were performed by PCCM fellows in an MICU in both cohorts. First-year fellows performed more intubations in the VL period as compared with the DL period, perhaps due to improved confidence of successful intubation. When using a VL, PCCM fellows were able to successfully complete the intubation 97% of the time without any attending intervention and were able to do so 91% of the time on the first attempt. To our knowledge, this is the first report documenting the superior performance of the VL in the setting of UEI outside the OR or ED when performed by nonanesthesiology trainees.
Additional strengths of this study include the standardization of UEI training between the 2 cohorts at the start of fellowship training and the prospective collection of data regarding the UEI outcomes. These results support the idea that relatively inexperienced clinicians adapted quickly to using the VL and were able to use it in critically ill patients who have high rates of complications such as hypotension, hypoxemia, aspiration, and death.5–9 We also found that the rate of hypotension and hypoxemia during both periods compare favorably with existing anesthesiology and critical care literature.5,8,18,19 We further tested our hypothesis during an earlier part of the academic year, which again showed superiority of the VL over the DL during UEI performed solely by first-year PCCM fellows.20
The VL is useful in OR intubation according to reports in the anesthesiology and emergency medicine literature.1–3,21,22 Esophageal intubation rates of novice operators were decreased when a VL was used compared with a DL in OR patients without predicted difficult airway.1 In a randomized controlled trial of experienced anesthesiologists performing tracheal intubation on patients with predicted difficult airway in the OR, use of a VL compared with a DL led to successful intubation in 100% vs 84% of patients, respectively.3 Two other reports indicated that glottic view by trained anesthesiologists was improved with a VL compared with a DL in patients with an anticipated difficult airway.21,22 First-attempt success in elective surgery patients by novice operators was 93% with a VL compared with 51% with a DL.23 Emergency medicine house staff achieved better glottic views with a VL compared with a DL.14 A recent meta-analysis of all randomized and quasirandomized trials comparing the GlideScope VL with a DL concluded that the GlideScope VL is associated with improved glottic visualization, especially in potential or simulated difficult airways. Although there was no difference in first-attempt success between the GlideScope VL and the DL among experienced laryngoscopists, benefits were seen in the nonexpert operators. Moreover, most studies included in this meta-analysis were performed in the OR setting and excluded patients with a predicted difficult airway.24 We studied nonanesthesiology operators performing UEI in the critically ill without any exclusion of patients with difficult airway predictors. Given the known difficult airway incidence of 6% to 22.5% in this population, the 91% first-attempt success achieved by nonanesthesiology trained operators is a significant achievement.5,9,25,26
Tracheal intubation performed by the anesthesiologist in the OR has low complication rates.27 The patients have stable physiology, are screened for difficult airway problems, and the practitioner who experiences unanticipated difficulty can potentially reverse the anesthesia and abort the procedure. Having the advantage of extensive procedure practice, anesthesiologists have expert manual skills in tracheal intubation. The number of procedures required to achieve proficiency in the manual skill of tracheal intubation in the controlled environment of the OR while using a DL is approximately 50.28–30 Konrad et al.30 reported that residents who were novice with respect to laryngoscopy required approximately 57 attempts to reach 90% first-attempt success using the DL in the noncritically ill. Of note is that 18% of these residents still required assistance after 80 intubations in the OR setting. Given the challenges of limited cardiopulmonary reserve, inability to abort the procedure, and the difficulty of assessing airway risk in the critically ill patient, it is difficult to know how many intubations are required to achieve a high level of proficiency with a DL to perform UEI in this patient population. Our opinion is that house staff, even including PCCM fellows, are not likely to perform a sufficient number of intubations during their fellowship training to be assured of definitive competence in the use of a DL. As patient safety is paramount during UEI, there is logic to using a VL as the primary intubating device for all UEIs performed by less experienced operators given its superior performance characteristics when compared with a DL and the difficulty in assuring that the house officer has a high level of proficiency in using the DL. Moreover, based on our data and other studies showing effectiveness of the VL in difficult airways, having one available for all UEIs in the critically ill could potentially offer a major safety advantage.10–15,21,22,31,32
This study has several methodologic limitations. The historical control trial design makes it possible that the benefits found in the intervention group may be the result of other unmeasured care, personnel, or treatment changes introduced over time. This is of concern given that the control and intervention periods were separated by 4 years, although both occurred in identical periods of the academic year and were chosen to ensure that both groups had no prior experience or training with a VL either during the PCCM fellowship or before. In addition, all of the fellows in both time periods were trained in identical fashion to execute the same protocol checklist-driven UEI sequence that was unaltered during the 2 time periods with the exception of the use of a VL as the primary device.
Another limitation is that the data collection methods differed between the 2 time periods. The DL period data were derived from analysis of audio recording of the UEI sequence supplemented by data from the MICU monitoring system when available. The VL period data were derived from real-time observation and scoring of the UEI sequence by an observer assigned to the UEI team. The reason for the change was practical. Scoring from audio records was very time consuming; therefore, it was not used during the VL period. We do not think that the change in the data collection method resulted in major bias. Another question is whether the 2 groups of patients were similar. Although patient demographics and disease characteristics were similar, predictors of difficulty of intubation such as the Mallampati score, thyromental distance, mouth opening, and neck extension cannot be reported with confidence, because they are difficult to assess in critically ill patients requiring UEI. We believe that it is unlikely that the VL and DL groups differed greatly in terms of difficult airway anatomy. We note that the assigned observer did not record the presence or absence of desaturation or hypotension in 8 and 3 patients, respectively, in the VL group. An analysis of the data assuming that all of these patients were hypotensive or desaturating does not change the conclusion that there were no significant differences between the VL and DL groups with regard to these 2 complications.
Our results combined with that of anesthesiology and ED literature support the assertion that video laryngoscopy has superior performance characteristics when compared with direct laryngoscopy tracheal intubation. The superior performance characteristics of the VL were observed when relatively inexperienced PCCM fellows used the device for UEI. On the basis of these observations and data from the ED, OR, and simulation-based settings, we would advocate training less experienced operators in the VL as the initial choice during UEI. In our program, we have established as policy among our first-year fellows that the VL be the primary intubation device for UEI in critically ill patients. Moreover, a VL is readily available for all tracheal intubations involving critically ill patients.
Name: Pierre Kory, MPA, MD.
Contribution: This author helped design and conduct the study, analyze the data, and write the manuscript.
Attestation: Pierre Kory 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.
Name: Keith Guevarra, DO.
Contribution: This author helped conduct the study, analyze the data, and write the manuscript.
Attestation: Keith Guevarra has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Joseph P. Mathew, MD.
Contribution: This author helped design and conduct the study, analyze the data, and write the manuscript.
Attestation: Joseph P. Mathew has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Abhijith Hegde, MD.
Contribution: This author helped design the study, analyze the data, and write the manuscript.
Attestation: Abhijith Hegde has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Paul H. Mayo, MD.
Contribution: This author helped design and conduct the study, analyze the data, and write the manuscript.
Attestation: Paul H. Mayo has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
This manuscript was handled by: Michael J. Murray, MD, PhD.
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