The physiologically difficult airway: an emerging concept

Abstract

Purpose of reviewThe physiologically difficult airway is one in which physiologic alterations in the patient increase the risk for cardiorespiratory and other complications during tracheal intubation and transition to positive pressure ventilation. This review will summarize the recent literature around the emerging concept of the physiologically difficult airway, describe its relevance and various patient types in which this entity is observed.Recent findingsPhysiologic derangements during airway management occur due acute illness, pre-existing disease, effects of anesthetic agents, and positive pressure ventilation. These derangements are especially recognized in critically ill patients, but can also occur in otherwise healthy patients including obese, pregnant and pediatric patients who have certain physiological alterations. Critically ill patients may have a physiologically difficult airway due to the presence of acute respiratory failure, hypoxemia, hypotension, severe metabolic acidosis, right ventricular failure, intracranial hypertension, and risk of aspiration of gastric contents during tracheal intubation.SummaryUnderstanding the physiological alterations and the risks involved in patients with a physiologically difficult airway is necessary to optimize the physiology and adopt strategies to avoid complications during tracheal intubation. Further research will help us better understand the optimal strategies to improve outcomes in these patients.

Failed tracheal intubation in primary health care

“…19 Besides anatomical changes mentioned here, there are some physiological changes that can lead to failure of optimised gas exchange after intubation. 3,4…”

“…However, apart from assessing predicted anatomic difficulties, identifying patients at risk for desaturation during intubation and maximising safe apnoea time by adequate and adapted preoxygenation should be the objective. 3,4…”

“…2 This concept mainly emphasises the anatomical difficulties of visualising the glottic opening or inserting the tracheal tube through the vocal cords. 3,4 However, in a very ill patient (or even in healthy patients), physiological changes prior to intubation may compromise the gas exchange after the endotracheal tube is placed; this constitutes a physiological failed intubation. 3,4 Most tracheal intubations are indicated for airway protection during surgical procedures or airway protection for trauma patients rather than respiratory failure.…”

“…3,4 However, in a very ill patient (or even in healthy patients), physiological changes prior to intubation may compromise the gas exchange after the endotracheal tube is placed; this constitutes a physiological failed intubation. 3,4 Most tracheal intubations are indicated for airway protection during surgical procedures or airway protection for trauma patients rather than respiratory failure. 5 In primary health settings, patients requiring tracheal intubations are those who are in need of general anaesthesia (GA) for obstetrics and gynaecology (laparotomy for ectopic pregnancy, sometimes C-section) for trauma and general surgery.…”

Recent advances in airway management

“…[ 2 ] There has been a recent focus on the management of physiologically difficult airways, in addition to anatomical difficulty. [ 3 ] This narrative review highlights the recent advancements with respect to innovations, tools, techniques, guidelines, and research in both technical and non-technical aspects of airway management. Lower airway management and ventilation strategies have not been covered.…”