By Eric Walter, MD, MSc
Pulmonary and Critical Care Medicine, Northwest Permanente and Kaiser Sunnyside Medical Center, Portland, OR
SYNOPSIS: In emergent intubations, a position in which the angle of the back was > 30 degrees above the horizontal (head-elevated) position was associated with fewer complications than intubations performed in the supine position, but the study has several limitations.
SOURCE: Khandelwal N, Khorsand S, Mitchell SH, et al. Head-elevated patient positioning decreases complications of emergent tracheal intubation in the ward and intensive care unit. Anesth Analg 2016:122:1101-1107.
Though a risky procedure, emergent endotracheal intubation often saves the lives of patients in the ICU. Steps should always be taken to minimize risks during endotracheal intubation procedures. The back-up, head-elevated (BUHE) patient position has been shown to improve glottis views and pre-oxygenation levels for surgical patients receiving direct laryngoscopy. The BUHE position also is different from the commonly known “sniffing position” in that the patient’s back is angled up and above the horizontal plane.
Seeking to retroactively discern the benefits of the BUHE position (also referred to as the head-elevated position in this study) as compared to the supine position, Khandelwal et al examined 528 cases of emergent intubation over a period of 18 months. For the purposes of the study, head-elevated positioning was determined as the angle of the back being inclined at least 30 degrees above the horizontal, and anything less than 30 degrees of elevation was considered supine. The study’s primary outcome was the rate of airway complications during or after intubation. Complications recorded included esophageal intubation, hypoxemia, pulmonary aspiration, and difficult intubation, which was defined as greater than two attempts at intubation, airway management of more than ten minutes, or a required surgical airway. In attempting to control for predicted intubation difficulty, Khandelwal et al determined MACOCHA scores, which is an amalgamation of a patient’s statuses in the categories of: Mallampati classification, sleep Apnea, Cervical mobility, mouth Opening, Coma, Hypoxemia, and intubation by a non-Anesthesiologist. At the relevant institutions for the study, nurse anesthetists or anesthesia trainees accompanied anesthesiologists in managing all ward and ICU intubations, so for study purposes, “non-anesthesiologists” were replaced by junior operators in calculating MACOCHA scores. A MACOCHA score of 3 or greater denotes difficult intubation.
Of the 528 events analyzed, 192 were performed in a head-elevated position, while the rest were performed in the supine position. Head-elevated patients were more likely to be intubated by senior operated and were less likely to have a MACOCHA score greater than 3. Complications occurred in 76 of the 336 supine patients, and in 18 of the 192 head-elevated patients. The difference between the two rates of complications was driven primarily by a significantly higher level of hypoxemia in the supine group (17% compared to 6.3%). Adjustment for body mass index and MACOCHA score showed that head-elevated position was associated with a lower odds of complication, but not lower odds of difficult intubation. These findings were not changed even after accounting for the experience of the operators.