Obstructive sleep apnea syndrome (OSA) is characterized by recurrent episodes of partial or complete upper airway obstructions during sleep. Severe OSA presents with a number of challenges to the anesthesiologist, the most life threatening being loss of the airway. We are reporting a case where we successfully used intraoperative bi level positive pressure ventilation (BiPAP) with moderate sedation and a regional technique in a patient with severe OSA posted for total knee replacement (TKR). A 55-year-old lady with osteoarthritis of right knee joint was posted for total knee replacement. She had severe OSA with an apnea-hypopnea index of 35. She also had moderate pulmonary hypertension due to her long standing OSA. We successfully used in her a combined spinal epidural technique with intraoperative BiPAP and sedation. She had no complications intraoperatively or post operatively and was discharged on day 5. Patients with OSA are vulnerable to sedatives, anaesthesia and analgesia which even in small doses can cause complete airway collapse. The problem, with regional techniques is that it requires excellent patient cooperation. We decided to put our patient on intraoperative BiPAP hoping that this would allow us to sedate her adequately for the surgery. As it happened we were able to successfully sedate her with slightly lesser doses of the commonly used sedatives without any episodes of desaturation, snoring or exacerbation of pulmonary hypertension. Many more trials are required before we can conclusively say that intraoperative BiPAP allows us to safely sedate OSA patients but we hope that our case report draws light on this possibility. Planning ahead and having a BiPAP machine available inside the operating may allow us to use sedatives in these patients to keep them comfortable under regional anaesthesia.
Keywords: Loss of airway; Obesity; Sedation.