Date: July 21, 2023
Reference: Prekker et al. Video versus Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults. NEJM 2023
Guest Skeptic: Dr. Jeff Jarvis is the Chief Medical Officer and System Medical Director for the Metropolitan Area EMS Authority in Fort Worth, Texas, also known as MedStar. He is board certified in both Emergency Medicine and Emergency Medical Services. Jeff discusses the application of research in EMS on his podcast The EMS Lighthouse Project.
Case: You are an emergency physician caring for a 65-year-old male with a history of hypertension and diabetes who presented with altered mental status, fever, and labored breathing. You’ve found that he is septic and in respiratory failure and needs intubation. Your assessment is that the patient will likely be a physiologically, but not anatomically, difficult airway. You’ve assured appropriate physiologic optimization and pharmacologic preparation and are ready to intubate. Should you go with video or direct laryngoscope?
Background: We have looked at this issue of intubation multiple times on the SGEM. The most recent discussion was about the use of etomidate as an induction agent (SGEM#405). The conclusion from that episode was it’s still uncertain if using etomidate decreases the patient-oriented outcome of survival with good neurologic function in critically ill patients requiring emergent endotracheal intubation.
The SGEM has also covered prehospital intubation using supraglottic devices for out-of-hospital cardiac arrests (OCHAs) with PA Missy Carter (SGEM#247 and SGEM#396). The take home message from those two episodes was that the airway is less important in adult OHCAs. We should focus more on high-quality CPR and early defibrillation for shockable rhythms and less on type of supraglottic airway device.
Using a bougie to increase the first pass success (FPS) rate was discussed on SGEM271. It showed the use of a bougie was associated with an increase in FPS. A hypothesized option of adding point of care ultrasound (POCUS) to our various methods of confirming correct placement of the endotracheal tube was covered on SGEM#249 with PA Chip Lange. We felt transtracheal sonography represents a potential fast and accurate way to help confirm endotracheal tube placement in conjunction with other methods.
Intubation FPS is associated with fewer adverse events, most importantly hypoxia, hypotension, and cardiac arrest. Traditionally, intubation was performed using direct laryngoscopes (DL) in which the soft tissues of the airway were physically displaced allowing direct visualization of the larynx, epiglottis, and vocal cords followed by passage of an endotracheal tube.
The challenging part of intubation using DL is usually visualization of the laryngeal structures while tube passage is relatively easy. Video laryngoscopes (VL) have been developed to improve the challenging part of DL, ie visualization.
Literature and clinical experience demonstrate that visualization is typically improved with VL, however, tube passage can be more challenging because the laryngeal structures are indirectly visualized.
The debate of DL vs VL goes back over a decade. We covered the issue with guest skeptic Dr. Steve Carroll on SGEM#75 (Video Killed Direct Laryngoscopy). That was an RCT from Baltimore Shock Trauma center comparing the two modalities. The primary outcome was no statistical difference in survival to hospital discharge between the two groups. The SGEM bottom line at the time was VL leads to the same outcome as DL in trauma patients. VL takes longer to accomplish and may be associated with higher mortality in patients with severe head injuries, however this relationship will require more study to confirm.
The literature comparing FPS between DL and VL is mixed with some trials, primarily earlier ones, demonstrated either no improvement with VL or superiority with DL, and others, primarily later ones, demonstrating improvement with VL. As the availability and experience with VL has grown, the question remains… does DL or VL use result in higher FPS.
Clinical Question: In adult patients needing intubation in an ED or ICU, is FPS higher with DL or VL?
Reference: Prekker et al. Video versus Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults. NEJM 2023
- Population: Adult patients 18-years-old and older seen in one of 17 academic ED or ICU needing endotracheal intubation for any reason.
- Exclusions: Under 18, pregnant, a prisoner, or there was inadequate time to allow for study randomization and enrollement. They were also excluded if, in the opinion of the treating physician, use of VL or DL is clearly either indicated or contra-indicated. In other words, the physician must feel that there is equipoise between DL and VL meaning that they have substantial uncertainty about whether DL or VL would result in better chances of FPS.Prehospital intubations were not included, nor were intubations performed in the OR.
- Intervention: First attempt intubation using a direct laryngoscope
- Comparison: First attempt intubation using a video laryngoscope. For VL with standard geometry blades in which direct visualization of the airway structures is possible, operators were instructed to view the video screen.
- Note: The use of bougie, stylet, blade geometry in both groups was at the discretion of treating physician. The approach to subsequent attempts was also at the discretion of the treating physician. All attempts were reported by the operator and confirmed by an independent observer who noted number of attempts at both laryngoscopy and tube passage, duration, and adverse events.
- Primary Outcome: FPS as defined by successful tube passage on the first attempt at laryngoscopy and a single attempt to pass the ET tube or bougie.
- Secondary Outcomes: Severe complications (SpO2 < 80%, SBP <65, new/increased use of pressors, arrest, death) occurring between induction and 2 minutes after intubation. Note that the time-period to define ‘peri-intubation’ varies widely in the literature. Lack of consistency it makes it hard to compare between studies.
- Type of Study: Multi-center, non-masked pragmatic randomized controlled trial.
Authors’ Conclusions: “Among critically ill adults undergoing tracheal intubation in an emergency department or ICU, the use of a video laryngoscope resulted in a higher incidence of successful intubation on the first attempt than the use of a direct laryngoscope.”
Quality Checklist for Randomized Clinical Trials:
- The study population included or focused on those in the emergency department. Yes
- The patients were adequately randomized. Yes
- The randomization process was concealed. Yes
- The patients were analyzed in the groups to which they were randomized. Yes
- The study patients were recruited consecutively (i.e. no selection bias). Unsure
- The patients in both groups were similar with respect to prognostic factors. Yes
- All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No
- All groups were treated equally except for the intervention. Yes
- Follow-up was complete (i.e. at least 80% for both groups). Yes
- All patient-important outcomes were considered. No
- The treatment effect was large enough and precise enough to be clinically significant. Yes
- Financial conflicts of interest. No disclosed conflicts that would likely impact study. The trial was funded by the US DoD and the methods were declared in advance on clinicaltrials.gov and published separately. The methods were not obviously different between the pre-trial disclosure and the final paper.
Results: 1,000 patients were included in the pre-planned interim analysis. The median age was 55 and 65% were male patients. The majority (70%) of the intubations were done in the ED with about ¼ being done for sepsis or septic shock and ¼ for traumatic injuries. The most common indications for intubation were altered mental status (45%) and acute respiratory failure (30%).
Key Result: First pass success rate was more common in the VL group compared to the DL group.
- Primary Outcome: FPS for VL 85.1% vs DL 70.8% giving an unadjusted absolute difference: 14.3% (95% CI; 9.9% to 18.7%)
- Secondary Outcomes: The point estimates for the various outcomes generally favoured VL
1. Consecutive Patients: Neither the paper nor the methods specify this, however the implication is recruitment was done with consecutive patients. No time limits (day hours) were noted. Assignment envelopes were consecutively numbered, but the manuscript does not specifically indicate that consecutive patients were enrolled if they met eligibility requirements.
2. Early Termination: There are many reasons why trials are stopped early (harm, benefit, futility, money, principal investigator leaves, etc). Stopping trials early can result in more uncertainty and lower precision around the point estimate. Early termination for benefit tends to over-inflate the effect size among other problems (Guyatt et al. BMJ 2012). A systematic review and meta-analysis reported industry funded studies are more likely to be stopped early for benefit (Montori et al JAMA 2005). It is still completely appropriate to stop trials early for benefit. The rationale should be determined and published a priori. This is exactly what these researchers did and they published their methods (Prekker et al BMJ 2023). There also guidelines which exist to assist researchers to determine when to terminate trials (Tyson et al. Trials 2016). For those interested in exploring this topic further check out the references at the end of the blog post.
3. Operator Dependant: There are a few things to unpack with this nerdy point. Some selection bias could have been introduced based upon the exclusion criteria. If the treating clinician did not think equipoise existed, the critically ill patient would not be enrolled. This is subjective and may have impacted the results.
The treating clinician could decide to use a bougie, stylet and their blade geometry. In addition, the approach used for any subsequent intubation attempts was also at the discretion of the treating physician. This was true for both groups.
It should be noted that this study started March 2022 during COVID. Many places had introduced policies requiring VL instead of DL. This could have impacted how some clinicians who were used to DL performed if assigned a VL case.
At this point, with current trainees, VL has a clear advantage in FPS over DL. This is almost certainly a function of operator’s familiarity and experience with VL vs DL, although visualization is clearly better with VL. Those operators with little prior overall experience or little experience with DL did better with VL. We cannot extrapolate these results to those highly experience with DL or anesthesiology. Interestingly there were no subgroups where DL showed an advantage and only operator experience with DL resulted in a non-significant advantage for VL.
4. Definition of FPS: This trial uses a novel definition for FPS.
“placement of an endotracheal tube in the trachea following a single insertion of a laryngoscope blade into the mouth and either a single insertion of an endotracheal tube into the mouth or a single insertion of a bougie into the mouth followed by a single insertion of an endotracheal tube into the mouth.
They compared this new FPS definition to what most of us are likely used to, that is a FPS is any successful intubation in which the tube is through the cords with one laryngoscopic insertion regardless of the number of attempts to pass the tube or bougie.
The difference in definitions is roughly 5% lower than the traditional definition but likely better reflects the assumed challenges with VL, particularly with a hyperangulated blade (visualization is easier but tube passage is often harder harder).
5. Primary Outcome: FPS is a surrogate measure, but an appropriate one given its association with adverse events. It is necessary, but not sufficient, for safe intubation. They did have a number of secondary outcomes with some being monitor oriented (SpO2 and SBP), some were subjective (need for vasopressors) and others were objective (death). They also had 11 of exploratory outcomes. Unfortunately, they did not seem to have one of the most important outcomes, survival with good neurologic function.
Comment on Authors’ Conclusion Compared to SGEM Conclusion: The authors’ conclusions are supported by the trial and seem reasonable.
SGEM Bottom Line: Clinicians should use the device they are most comfortable and experienced with. If they’re highly experienced with DL and very successful with it, they should likely continue to use it.
Case Resolution: Jeff would usually reach for VL and Ken would usually reach for DL.
Clinical Application: Video laryngoscopes have added a new tool to the clinician’s airway management toolbox. VL, particularly with hyperangulated blades, make visualization easier but may make tube passage more challenging. Techniques for tube passage are different with these blades and clinicians must learn these techniques. DL obviously works as well as it always has and if that’s the technique, you’re familiar and success with, keep doing what you’re good at. I’d caution against subjective assessment of provider’s success, though. When it comes to intubation, almost all clinicians are like the children from Lake Wobegon… “we’re all above average”.
- Lake Wobegon is a fictional town created by Garrison Keillor as the setting of the recurring segment “News from Lake Wobegon” for the radio program A Prairie Home Companion broadcast from St Paul, Minnesota. He would typically end his show saying “That’s the news from Lake Wobegon, where all the women are strong, all the men are good-looking, and all the children are above average.”
What Do I Tell the Emergency Physician? You should use the device they are most experienced and successful with. If you have limited (<100) prior intubations and most of those were with VL, you should almost certainly use VL. If you have lots of experience with DL, and little experience with VL, DL is probably still better option for you.
Keener Kontest: Last weeks’ winner was Dr. Cindy Bitter a long time listen and multiple keener contest winner. She knew the trial for a universal flu vaccine using mRNA technology is a Phase I trial. I am sending you one of the new prizes.
Listen to the podcast this week to hear the keener question. If you think you know the answer then send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.
- St. Emlyn’s: JC Video vs. Direct Laryngoscopy for Tracheal Intubations of Critically Ill Adults
- EMS Lighthouse Project: VL vs DL
Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.
- Lievre M, Menard J, Bruckert E et al. Premature discontinuation of clinical trial for reasons not related to efficacy, safety, or feasibility. BMJ 2001; 322: 603-5.
- Psaty BM, Rennie D. Stopping medical research to save money. A broken pact with researchers and patients. JAMA 2003; 289: 2128-31.
- Chopra SS. Industry funding of clinical trials: benefit or bias? JAMA 2003; 290: 113-4.
- Bassler D, Matthias et al. Stopping randomized trials early for benefit and estimation of treatment effects: systematic review and meta-regression analysis. JAMA 2010; 303: 1180-1187.
- Briel, M, Bassler, D, Wang, AT, et al. The dangers of stopping a trial too early. JBJS 2012; 94: 56-60.
- Viele, K, McGlothlin, A, & Broglio, K. Interpretation of clinical trials that stopped early. JAMA 2016; 315: 1646-1647.
- Mueller PS, Montori VM, Bassler D, Koenig BA, Guyatt GH. Ethical issues in stopping randomized trials early because of apparent benefit. Ann Intern Med. 2007 Jun 19;146(12):878-81. doi: 10.7326/0003-4819-146-12-200706190-00009. PMID: 17577007.
- Wears RL. Are we there yet? Early stopping in clinical trials. Ann Emerg Med. 2015 Feb;65(2):214-5. doi: 10.1016/j.annemergmed.2014.12.020. PMID: 25601251.