ANESTHETIC CARE OF THE PATIENT WITH OBSTRUCTIVE SLEEP APNEA
AMIR BALUCH*, SUNIL MAHBUBANI**, FAHAD AL-FADHLI***, ALAN KAYE**** AND ELIZABETH A.M. FROST***** Introduction
Obstructive sleep apnea (OSA) is an insidious, progressive disease1 that is significantly under diagnosed in the general population. It carries increased risk of difficult intubation preoperatively2 and increased risk of postoperative respiratory depression and airway collapse leading to hypoxia and possibly asphyxia3. In light of the estimated prevalence of symptomatic OSA in 5%4 of the general populace, and the fact that 80% of these patients remain undiagnosed5, it is crucial for anesthesia personnel to screen every patient undergoing anesthesia for this disorder quickly and effectively, and likewise, to have a strategy for perioperative care.
Several commonly used terms include: 1. Obstructive Apnea: an absence of airflow during sleep for greater than 10 seconds6,7. 2. Obstructive Hypopnea: The latest manual of the American Academy of Sleep Medicine (AASM) provides two definitions of hypopnea. The recommended definition is a drop in desaturation. 3. Obstructive Sleep Apnea: recurrent apneic and/or hypopneic episodes despite continuing 6,7 . 4. Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS): symptomatic OSA. The main symptom is daytime sleepiness, but symptoms can manifest as choking or gasping during sleep, recurrent awakening during sleep, unrefreshing sleep, and impaired concentration6,7. 5. Apnea-Hypopnea Index (AHI): a tool used to diagnose and measure the severity of OSA by measuring apneic-hypopneic events per hour during sleep. An AHI greater than 5 but less than 15 is the criteria for mild OSA. Moderate OSA is defined by an AHI greater than 15 but less than 30, and severe OSA is an AHI greater than 306. Respiratory Disturbance Index (RDI) is the same measurement as AHI8. * MD, Anesthesia Resident, Jackson Memorial Hospital/University of Miami, Miami, Florida, USA. ** MD, Emergency Medicine Resident, Texas Tech University Health Sciences Center, El Paso, TX, USA. *** MD, Department of Radiology, University of Mississippi Medical Center, Jackson MS, USA. **** MD/PhD/DABPM, Professor and Chairman, Department of Anesthesiology, Louisiana State University Health Science Center, New Orleans, LA, USA. ***** MD, Professor, Mount Sinai Medical Center, New York NY, USA. Corresponding author: Amir Baluch MD, Jackson Memorial Hospital, University of Miami, Miami, Florida, USA. E-mail: email@example.com The authors have no relationships with pharmaceutical companies or products to disclose, nor do they discuss off-label or investigative products in this manuscript.
M.E.J. ANESTH 20 (2), 2009
6. Sleep Disordered Breathing (SDB): a spectrum of disorders based on irregular breathing during sleep. It includes obstructive sleep apnea-hypopnea syndrome, central sleep apnea syndrome (recurrent apneic-hypopneic events during sleep without upper airway obstruction), Cheyne-Stokes breathing syndrome (the waxing and waning breathing patterns of patients with cardiac dysfunction or intracranial disease), and sleep hypoventilation syndrome (hypoxia for greater than 50% of sleep without apneic-hypopneic events)6. 7. Chronic Intermittent Hypoxia: the physiologic terminology for chronic repetitive episodes of oxygen desaturation and resaturation unique to SDB disorders.
AMIR BALUCH ET. AL
Obesity is the most common modifiable risk 3 . Lifestyle modifications aimed at losing weight are the best way to decrease the number of nighttime apneas/ hypopneas. Changes in obesity have been shown to directly correlate with disease severity (Figure 1)1.
Pathogenesis of Upper Airway Collapse
OSA is a progressive disorder of the obese4. Fat deposition in the upper airway (UA) is most common at the lateral pharyngeal walls, decreasing pharyngeal caliber and adding external compression forces on the pharynx13. The...