title: Obstructive sleep apnea uncovered after high spinal anesthesia: a case report.
abstract: OBJECTIVE
  To illustrate how a patient's previously undiagnosed obstructive sleep apnea was uncovered after administration of a spinal anesthetic with a high sensory blockade, and to discuss possible explanations for this occurrence and anesthetic implications.
  
  
  METHODS
  A 55-yr-old male presented for osteotomy and open reduction and internal fixation of his left femur secondary to malunion from a previous fracture. Past medical history consisted of hypertension, hypercholesterolemia, bipolar disorder, gastroesophageal reflux disease, and cluster headaches. A combined spinal-epidural technique was chosen. Isobaric bupivacaine 0.5% (15 mg), was provided for the spinal anesthetic, along with 1 mg iv midazolam for procedural sedation and 0.5 mg iv droperidol for mild nausea. Throughout the operation, many apneic events were noted, often with respiratory efforts. The patient was easily arousable during each event and would breathe normally until the next episode. Vital signs remained stable throughout. Postoperative respirology consultation was requested, and a sleep study revealed severe obstructive sleep apnea. The patient was subsequently started on continuous positive airway pressure with marked improvement in symptoms, including the cluster headaches.
  
  
  CONCLUSIONS
  Recent literature suggests that high spinal blockade can result in altered levels of arousal by producing a de-afferentation of peripheral proprioceptive and sensory stimuli necessary for maintaining an awake state. In patients predisposed to upper airway obstruction, decreasing the level of consciousness can result in airway obstruction as occurs during sleep in these patients. This serves to underline the importance of considering capnography for all cases utilizing a neuraxial anesthetic technique.
authors.affiliation: Department of Anesthesia, D10-144, Montreal General Hospital, 1630 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada. paul.wieczorek@mail.mcgill.ca
authors.forename: Paul M
authors.initials: PM
authors.lastname: Wieczorek
authors.forename: Francesco
authors.initials: F
authors.lastname: Carli
mesh_terms: D000767:Anesthesia, Epidural; D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000008:administration & dosage; D000932:Antiemetics / Q000627:therapeutic use; D002045:Bupivacaine / Q000008:administration & dosage; D045422:Continuous Positive Airway Pressure; D004329:Droperidol / Q000627:therapeutic use; D005264:Femoral Fractures / Q000601:surgery; D017759:Fractures, Malunited / Q000601:surgery; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D008297:Male; D008874:Midazolam / Q000008:administration & dosage; D008875:Middle Aged; D020250:Postoperative Nausea and Vomiting / Q000517:prevention & control; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000628:therapy
chemical_list: D000779:Anesthetics, Local; D000932:Antiemetics; D006993:Hypnotics and Sedatives; D004329:Droperidol; D008874:Midazolam; D002045:Bupivacaine