Oxygen Saturation Monitoring During Surgery

Patients with Obstructive Sleep Apnea (OSA) have episodes of upper airway obstruction during sleep which have been shown to be accompanied by multiple oxygen desaturations followed by short recovery intervals until rising PaCO2 causes sleep disruption/rescue arousal. In the postoperative and conscious sedation arena, these patterns can deteriorate from a stable pattern to a severely unstable pattern which may go unrecognized and lead to an adverse event (respiratory/cardiac arrest; death).

Anesthesia and the higher consumption of analgesics produce a profound reduction in pharyngeal tone, a dampening of both chemoreceptor sensitivity and arousal/rescue response. Thus the first 48 hours post operatively presents a vulnerable period. Respiratory disturbances are more prominent - respiratory arrest and hypopnea being the main adverse occurrences during this period.

An algorithm has been developed that monitors saturation and indicates repetitive reductions in airflow through the upper airway and into the lungs. Presence of this pattern in the procedural sedation patient population has not been tested for its prevalence. This study will monitor patients during surgery to determine if this pattern occurs in this hospital setting.

Inclusion criteria

• Age greater than 21 years
• Patients scheduled for a procedure that requires analgesia and/or sedation by any route (intravenous, intramuscular, oral, epidural or intrathecal).
• Patients with an anticipated length of sedation greater than or equal to one hour.
• Patients in the ASA category I through III.
• Patients who only receive propofol, benzodiazepines, and opioids.

Exclusion criteria

• Age less than 21 years
• Patients whose room air oxygen saturation is <90%
• Patients receiving post-operative positive airway pressure support
• Previous allergic/contact reactions to adhesives
• CHF
• Moderate or severe valvular disease
• TIA/CVA
• Carotid stenosis or endarterectomy
• Anemia (HCT if available < 30%)
• Pulmonary hypertension
• Dialysis
• Pregnancy
• Patients unable to give informed consent