Background: Rapid Sequence Intubation (RSI) is a common procedure performed by both emergency clinicians and intensivists. Although the procedure is complex, the major pieces are pre-oxygenation, administration of a sedative agent in close proximity with a paralytic, laryngoscopy and placement of an endotracheal tube without the provision of any ventilations during the process. The avoidance of bag-mask ventilations (BMV), or any positive pressure breaths, rests on the belief that those breaths can distend the stomach and lead to regurgitation and aspiration. For this to happen, the force of the breath must exceed the pressure of the lower esophageal sphincter (~ 20 mm Hg). Critically ill patients presenting with airway compromise cannot be guaranteed to have a fasting state, regurgitation and aspiration is a major concern.
However, there’s another side to this. Many of our patients who are critically ill have intrapulmonary shunting; portions of the lung are atelectatic, filled with fluid, blood, or pus and not being oxygenated though they are being perfused. Blood running through these portions of the lung will be deoxygenated and will lower the overall O2 content of blood entering the systemic circulation after mixing with blood coming from ventilated regions. This shunting at least partially explains why we see patients rapidly desaturating during intubation. Positive pressure can recruit atelectatic portions of the lung that are not involved in gas exchange thus decreasing the physiologic shunt and increasing the patient’s oxygen reserve.
Despite decades of experience with RSI we continue to look for better approaches since the procedure still poses serious risks to the patient. Recent modifications that have seen wide adoption include using the bed-up-head-elevated (BUHE) position, suction assisted laryngoscopy for airway decontamination (SALAD) and bougie first intubation, though there are many more. Now, a publication in the NEJM makes us question the core principle of BMV during RSI....Read More
Take Home Points
Background: Cricoid pressure is dead, right? Many have made this claim including a brilliant argument against its use by John Hinds here. Despite the many eulogies, we continue to hear about cricoid pressure so it makes sense that we dive in to the background prior to addressing the recent JAMA Surgery publication.
Cricoid pressure was first described by Dr. Sellick in the 1960’s though similar techniques were described as far back as the 1770s (Sellick 1961). The Sellick’s maneuver entailed the application of pressure over the cricoid cartilage with the thumb and 1-2 additional fingers. The goal was to compress the cricoid cartilage against the esophagus in order to occlude the esophagus and prevent regurgitation of stomach contents into the upper airway. Initial studies on the maneuver suffered from a bevy of methodological flaws including small n, lack of blinding or randomization and selection bias. Despite this, Sellick’s maneuver was widely adopted and taught to hordes of anesthesia, critical care and emergency residents.
Studies investigating cricoid pressure in the last decade have demonstrated a number of issues with claims that it can prevent passive regurgitation. Check out this free chapter on EMRAP for an in depth discussion. Dynamic MRI studies demonstrate that application of pressure to the cricoid cartilage displaces the esophagus laterally instead of occluding it (Smith 2003, Boet 2012). An ultrasound study demonstrated similar findings: in 60% of patients the esophagus was lateral to the airway and cricoid pressure led to displacement rather than occlusion in all patients. (Tsung 2012).
Additionally, application of cricoid pressure decreases airway patency and increases the chance that your view of the airway will be obscured. (Allman 1995, Palmer 2000, Smith 2002, Oh 2013). Finally, no study to date has demonstrated a reduction in aspiration episodes with the application of cricoid pressure. A large observational study of pregnant patients undergoing C-sections found no difference in aspiration events and that the overall aspiration event rate was low (Fenton 2009). However, up until this point, there has not been a high-quality, randomized controlled trial performed....Read More
Background: Administration of a neuromuscular blocker (NMB) is an essential part of Emergency Department (ED) airway management for facilitating ideal airway conditions and is most commonly performed with either succinylcholine or rocuronium. Despite extensive debates between providers, one agent has not been shown to be superior to other. Limited anesthesia literature has shown that succinylcholine may provider better intubating conditions but it has a number of contraindications (which may not be initially apparent)(Shoenberger 2018). Rocuronium at high doses has a similar onset of action to succinylcholine and may provider longer safe apneic times (Swaminathan 2018). This study seeks to add more information to the clinical discussion....Read More