While preparing for intubation, the operator must adjust the patient’s position to optimize laryngoscopy, endotracheal tube delivery, and to reduce the risk of adverse events. There has been debate over time, however, regarding the ideal positioning to maximize safe apnea time, success rates, and reduce complications during rapid sequence intubation (RSI).¹ This chapter will summarize the literature to-date and present a practical approach to patient positioning using the “Back-Up Head-Elevated,” (BUHE) and “sniffing” positions to optimize first-pass success and safe apnea time during RSI in critically ill patients ( Video 19.1).^2,3,4,5

Studies suggest that at least 20 degrees of head elevation improves the efficacy of preoxygenation and prolongs safe apnea time.⁶ Head of the bed at 25 degrees or sitting likely contributes to an increase in functional residual capacity (FRC) and particularly seems beneficial for patients with obesity.^7,8 Thus, we recommend preoxygenating in an upright position if possible. Reverse Trendelenburg position (as opposed to “beach chair”) appears to increase the benefits of head elevation to avoid compressing the lungs between the bed and the abdomen and legs.^9,10 Reverse Trendelenburg is preferable when limited by spine or hip immobility and in instances of large abdominal girth.¹¹

The majority of studies on positioning involve direct laryngoscopy (DL).^1,5,12 However, it logically follows that any maneuver that improves visualization of the glottis with DL will likely improve tracheal tube delivery with either DL or VL, as the direct line of site from the operator’s eyes to the larynx is the same direct path a styletted endotracheal tube must take (Fig. 19.1). This is similar to the three-axis alignment theory first described in 1944, which related the axes of the oral, pharyngeal, and laryngeal planes.¹³ This theory states that the lower the curve angle through the mouth, pharynx, and larynx, the easier glottic visualization and tracheal tube delivery to the level of the glottis should be. We can add a fourth component, which is the operator’s line of site through these three axes to explain how operator position may impact tube delivery in any position. Thus, if the operator has a clear line of site through these three axes, there should be a more direct path for tube placement as well. However, if the operator is unable to visualize this path due to malpositioning, then passage of an endotracheal tube may also be impeded regardless of the laryngoscope.

The most commonly studied positions for RSI include the “sniffing position,” and varying degrees of a ramped position. The sniffing position is best described as the “ear-to-sternal notch” position, meaning that the neck is flexed at the lower cervical spine, lifting the occiput such that the ear is approximately in line with the sternal notch height and the head is extended at the upper cervical spine (Fig. 19.2).^5,14 The sniffing position has demonstrated improved glottic visualization when compared directly with neutral alignment or simple head extension.^3,5,12 This is often compared to ramping the patient with back elevation (elevation of the head to at least 25 degrees), which has mixed results in the literature.^1,15,16,17 Some of this variability may be related to the height of the operator above the bed, which is often not reported but does have a significant impact on aligning the visual axes (Fig. 19.3). Direct comparisons of a ramped position versus sniffing position also fail to capture the potential additive properties of combining the two approaches. Combining ramping and sniffing positions is the “Back Up” (i.e., ramped) “Head Elevated” (i.e., sniffing) BUHE position, and is advantageous in the critically ill.^18,19