Pharmacologically Induced Ventilatory Depression in the Postoperative Patient: A Sleep-Wake State-Dependent Perspective

Abstract

Pharmacologically induced ventilatory depression (PIVD) is a common postoperative complication with a spectrum of severity ranging from mild hypoventilation to severe ventilatory depression, potentially leading to anoxic brain injury and death. Recent studies, using continuous monitoring technologies, have revealed alarming rates of previously undetected severe episodes of postoperative ventilatory depression, rendering the recognition of such episodes by the standard intermittent assessment practice, quite problematic. This imprecise description of the epidemiologic landscape of PIVD has thus stymied efforts to understand better its pathophysiology and quantify relevant risk factors for this postoperative complication. The residual effects of various perianesthetic agents on ventilatory control, as well as the multiple interactions of these drugs with patient-related factors and phenotypes, make postoperative recovery of ventilation after surgery and anesthesia a highly complex physiological event. The sleep-wake, state-dependent variation in the control of ventilation seems to play a central role in the mechanisms potentially enhancing the risk for PIVD. Herein, we discuss emerging evidence regarding the epidemiology, risk factors, and potential mechanisms of PIVD.

An update on postoperative respiratory depression

“…2A). There are several important changes in neural control of breathing which occur during sleep, 11 which may explain the nocturnal distribution of postoperative RD. Upper airway patency depends on both phasic and tonic neural input to pharyngeal muscles.…”

“…During sleep, the tonic Adapted from Doufas and Weingarten. 11 Adaptations are themselves works protected by copyright. So in order to publish this adaptation, authorization must be obtained both from the owner of the copyright in the original work and from the owner of copyright in the translation or adaptation.…”

“…This low rate of naloxone administration presents a challenge toward designing adequate prospective randomized trials to examine the safety of specific analgesic technique, because these studies would require a prohibitively high patient sample size to establish the risk of respective treatment. As discussed by Doufas and Weingarten, 11 "with a rate of naloxone administration of 10 per 10,000 cases, to detect a doubling of the incidence from a drug (a relative risk of 2), with 80% power, would require a cohort of approximately 23,000 subjects per treatment arm. "…”

Perioperative considerations for adult patients with obstructive sleep apnea

“…Recently, bedside capnography has been used in the PACU to detect postoperative respiratory depression, and this technology may provide a more reliable mechanism to detect respiratory depression than subjective diagnoses by healthcare staff [58]. Technology for continuous monitoring is rapidly evolving [39], and the optimal monitoring technology has not been established, but the clinician should appreciate that with the use of supplemental oxygen pulse oximetry becomes less sensitive than other monitors of respiratory effort [8 ▪▪ ].…”

Ambulatory surgical patients and sleep apnea

“…27 Opioid use should be limited because patients with OSA have an increased likelihood of opioid-induced respiratory complications due to opioid interference with the ventilatory control center. 2,9,26 Opioids diminish the respiratory response to hypoxia and hypercarbia, which is more pronounced in patients with OSA and lead to airway obstruction and central apnea. There is also evidence to support chronic hypoxia leading to exaggerated opioid-related side effects.…”