Exploring Dogma: Critically Appraising the Evidence Behind Our Daily Clinical Practice

Allison M. Janda, MD

How does dogma contribute to our practice patterns, habits and approach to clinical care? Hosts of the popular podcast, “Depth of Anesthesia,” David Hao, MD, and Daniel Saddawi-Konefka, MD, MBA, set out to discover the answer in a live session, “Exploring Clinical Dogma with the ‘Depth of Anesthesia’ Podcast Team” held Sunday, March 20 at the IARS 2022 Annual Meeting. They raised the idea that we should critically assess the evidence behind our own habits, and reconsider those habits that are contradictory to new or emerging evidence. The goal of their podcast is to critically appraise the level of evidence behind dogmatic clinical practices, provide updates on the evidence supporting these claims, and disseminate evidence across the field of anesthesia. Their critical lens led to an enlightened discussion.

David Hao, MD, Clinical Fellow, Massachusetts General Hospital, and Daniel Saddawi-Konefka, MD, MBA, Assistant Professor of Anesthesiology and Critical Care and Residency Program Director at Massachusetts General Hospital, led an interactive and case-based session that invited input from the audience through surveys including level of agreement polls and free-text responses. The first case focused on airway management for a 120kg male presenting for a laparoscopic umbilical hernia repair. They highlighted how many habits are embedded in a given stem, but the habit they focused on was confirmation of the ability to mask ventilation prior to administering neuromuscular blockade (NMB). The live poll showed multiple opinions on this practice. Drs. Hao and Saddawi-Konefka then highlighted that it would be incredibly difficult to perform a multicenter randomized clinical trial to answer this question definitively and therefore, we have to use principles and upstream measures to conduct a critical appraisal of the available evidence. To do this, they then dove into a head-to-head comparison on each subclaim that was highlighted under each rationale.

Drs. Hao and Saddawi-Konefka first addressed claims for the “check first” rationale including, “the patient would be able to emerge from the induction dose prior to desaturation,” and “administration of neuromuscular blockade would further delay return of spontaneous respiration.” They provided an excellent overview of the literature and how these studies differed from one another. They summarized that the time to desaturation ranges and depends on BMI, angle of the head of bed or positioning of the patient, degree of preoxygenation, pulmonary comorbidities, and application of an additional oxygen source for apneic oxygenation as demonstrated by prospective trials (Jense et al., 1991., Dixon et al., 2005). They also synthesized the data regarding the time from induction to return of spontaneous ventilation. Their examination included multiple prospective trials which inspected multiple induction agents and dosing strategies both with and without paralytic (Stefanutto et al., 2012; Jiao et al., 2014; Tanaka and Nishikawa, 2003; El-Orbany et al., 2004; Dwivedi et al., 2018; Goh et al., 2005; Lee et al., 2009). In summary, the times to return of spontaneous ventilation both with and without NMB administration were very close to the times noted in the previously mentioned studies. Therefore, if we want the patient to emerge prior to desaturation to the point of no return, these values should be more temporally separated.

To address the claims made by the “don’t check” rationale, the claim, “NMB consistently helps with mask ventilation” was examined next. They started by summarizing the findings from Warters et al. (2011) who graded the ease of mask ventilation after induction, and then again after either saline or rocuronium administration and found that the rocuronium group had improved ease of mask ventilation scores. Schadeva et al. (2014) used a protocolized masking technique and measured the mean tidal volume after induction, and again after administration of NMB and ensuring train-of-four was zero. They found improvement in tidal volumes after administration of rocuronium, but they only had 8 patients with a difficult-to-mask designation. Soltész et al. (2017) specifically studied 113 patients with at least 3 risk factors for difficult mask ventilation and found that tidal volumes increased from 350 to 600cc after administration of rocuronium in this more challenging population. Drs. Hao and Saddawi-Konefka summarized that, although these studies show that ease of mask ventilation or tidal volumes were either unchanged or improved after NMB administration, these studies were conducted in specific surgical populations and under set protocols and may not be generalizable to all of clinical practice. They then turned to a large retrospective observational study, which found that 77 out of 53,041 patients were found to be impossible to mask ventilate, 58 of which were intubated with standard techniques, 15 were intubated with alternative techniques (with the implication that these two groups received a NMB), 3 were emerged, and 1 required an emergent surgical airway (Kheterpal et al., 2009). Drs. Hao and Saddawi-Konefka noted a large prospective study by  Amathieu et al. (2011) which studied 12,225 patients for which any patient who had a known difficult or potentially difficult airway received immediate administration of succinylcholine, and found that administration of succinylcholine never worsened the ability to mask.

This excellent session concluded by revisiting the audience poll, which showed a change in some of the results after the presentation and discussion of the evidence supporting each claim. Drs. Hao and Saddawi-Konefka emphasized that more deep dives into the reasoning behind clinical practice and dogma is necessary for continued practice improvement and evaluation of best practice. This well-organized and clear live session is a “must view” if you weren’t able to attend live and episodes for the podcast, “Depth of Anesthesia” hosted by Drs. Hao and Saddawi-Konefka, are available on their website and can also be accessed via Spotify and Apple.