Clinical Trial Insights: Intubation Methods Explored

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. Missy Carter 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. Chip Lange PA 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. Outcome: 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.