The prevalence of obstructive sleep apnoea (OSA) is 9% in the surgical patient population , but more than 50% in morbidly obese patients undergoing bariatric surgery . Patients with OSA are prone to postoperative respiratory dysfunction because of the respiratory depressant and pharyngeal hypotonia effects of opioids, sedatives and anaesthetics [1,3,4]. Thus, the perioperative use of these medications is usually restricted in patients with OSA [1,3,4]. There is a scarcity of clinical information on the use of dexmedetomidine in patients with OSA undergoing bariatric surgery. This clinical report is based on observations of the perioperative course of dexmedetomidine-based anaesthesia in a cohort of 22 patients with OSA who underwent laparoscopic bariatric surgery.
The patients were adults, aged 25–57 years, with BMI in the range of 44–91 kg m−2, and airway scores of Mallampati 1–3. They underwent elective laparoscopic gastric bypass surgery at the University of Michigan Hospital, Ann Arbor, USA. The patients had OSA and used nocturnal continuous positive airway pressure (CPAP) ventilation regularly. They had other comorbidities as shown in Table 1.
Physiological monitoring of the patients was initiated with pulse oximetry, electrocardiography and noninvasive blood pressure measurement. Intravenous (i.v.) dexmedetomidine was commenced preinduction with a loading dose of 1 μg kg−1 over 10 min, followed by 0.4 μg kg−1 h−1 infusion. This resulted in light sedation without airway or cardiorespiratory compromise, and oximetry was more than 95% with supplemental facemask oxygen.
The patients were subsequently preoxygenated, and rapid sequence anaesthesia induction was performed using i.v. propofol (1.5 mg kg−1) and succinylcholine (1 mg kg−1), followed by endotracheal intubation. Anaesthesia was maintained with sevoflurane, atracurium and dexmedetomidine at 0.5–0.7 μg kg−1 h−1. Intraoperative monitoring included oximetry, electrocardiography, blood pressure measurement, capnography, gas analysis and temperature measurement. Supplemental analgesia was provided with i.v. ketorolac 30 mg. At completion of surgery, sevoflurane was discontinued and neuromuscular blockade reversed. With adequate spontaneous respiration, pulse oximetry, arterial blood gases and response to voice, dexmedetomidine infusion was discontinued. Patients were extubated uneventfully in the sitting posture and were fully conscious. Postoperatively, supplemental facemask oxygen was administered, patients were physiologically stable and oximetry was more than 94%. The average pain score was 0/10 in the 1st hour and 2/10 in the 2nd–3rd hour when patients were discharged from the recovery room. CPAP devices were available for postoperative use, but not required. There was no exacerbation of comorbidities and no perioperative events.
Postoperative hypoventilation and hypoxia is common in patients undergoing bariatric surgery . The problem is particularly worse in patients with OSA because of preoperative sleep deficit, residual anaesthetic effects, opioid depressant effect and pharyngeal hypotonia. An effective perioperative sedative/analgesic that is void of significant central and cardiorespiratory depressant activity will minimize the dose of anaesthetic/analgesic required, thus enabling better postoperative emergence, recovery and respiration in patients with OSA undergoing bariatric surgery. Dexmedetomidine is an agent with these desirable effects that may be beneficial for patients with OSA and for bariatric surgery.
Dexmedetomidine is a short-acting, highly potent, selective α2 adrenoceptor agonist with unique analgesic, sedative, amnesic and anaesthesia-sparing properties [6,7]. At recommended clinical doses, it is void of significant cardiorespiratory depressant activity, produces significant opioid-sparing analgesia and has anaesthesia-sparing properties; thus enabling better emergence and minimizing the risk of postoperative hypoventilation [6,7]. This is beneficial in patients with OSA undergoing bariatric surgery, as demonstrated by the uneventful preoperative sedation, emergence and postoperative recovery of the patients described. Their airway scores were Mallampati 1–3; with grade 1–2 laryngoscopic views; however, if patients with OSA or those undergoing bariatric surgery require awake fibreoptic intubation, this could be facilitated by the use of dexmedetomidine without cardiorespiratory compromise . Extubation in patients with OSA or in those undergoing bariatric surgery is potentially problematic and should be performed in a conscious and sitting patient; as was successfully performed in the patients described in this report. In conclusion, dexmedetomidine is a potentially useful anaesthetic/analgesic adjunct in patients with OSA undergoing bariatric surgery. It may also be useful for endoscopy and sleep studies in these patients. Further research and experience is required.
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