CME Module 11: Obstructive Sleep Apnea and the Anesthesia Patient Next >

 

Introduction

 

An alarming number of Canadians and Americans suffer from obstructive sleep apnea (OSA), a disorder whereby oropharyngeal soft tissue intermittently obstructs the airway during sleep [1-5].  If undetected, OSA can lead to serious health problems, as well as result in significant perioperative complications [6-9].  Patients with OSA may complain of snoring, daytime sleepiness, repeated morning headaches, intellectual impairment and other symptoms. They may sometimes fall asleep at inappropriate times, such as during a conversation, while watching TV, while traveling in a car, and even while stopping at a stoplight while driving. What is especially concerning is that the prevalence of OSA is expected to rise as the population ages and becomes more obese. 

Because OSA is undiagnosed in the majority of patients, anesthesia providers should be aware of the clinical presentation and how is OSA diagnosed. The perioperative concerns in patients with OSA are primarily respiratory in nature, and include airway obstruction, the potential for difficult intubation and mask ventilation, and an increased chance for clinical misadventures when opiates are administered. In addition, potential nonrespiratory concerns also abound: studies have established a link between OSA and heart failure, ventricular hypertrophy (right-sided first, then left-sided), systemic and pulmonary hypertension, cardiac rhythm disturbances, as well as vascular disease.

As noted above, OSA  involves repetitive partial or complete upper airway obstruction from collapse of the pharyngeal airway during sleep. This typically occurs despite continued movement of the diaphragm and can lead to apneas (with complete obstruction), hypopneas (with partial obstruction) and respiratory effort-related arousals.  The last of these can occur without desaturation, while hypoxia itself leads to arousal from sleep, with reopening of the airway and the intake of a breath. Severity is related to the number of these respiratory events per hour as determined by polysomnography.

Determining which clinical features predict that OSA is present has been the subject of considerable recent research, and has resulted in a number of clinical assessment tools (vide infra). For example, the ASA has published a task force report entitled “Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea”  [10] that we will be studying later in this module, along with some other clinical assessment tools such as the Berlin questionnaire, the STOP questionnaire and the  STOP-Bang questionnaire. The primary purpose of the present module, then, is to discuss the pathophysiology of OSA and to summarize some of these important guidelines. To add a clinical focus, the module will also present three brief clinical cases to consider.
Next >