Journal des troubles du sommeil et de la thérapie
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CPAP for Obstructive Sleep Apnea in the Post-Operative Setting: An Oximetry Evaluation Study

Inderjeet S Brar, Ramakant Sharma, Gaurav Khanna and Dennis Auckley

Objective: To study the prevalence and associations of nocturnal hypoxia following surgery in PAP-treated (CPAP or bilevel pressure support) OSA patients.

Patients and Methods: PAP-treated OSA patients presenting for elective surgery (n=38) between August 2007 and October 2008 underwent overnight oximetry monitoring on their prescribed PAP therapy on postoperative night one. The lowest oxygen (O₂) saturation (SpO₂), time spent with SpO₂ <89% and the presence of sleep disordered breathing (saw-tooth oscillations) were determined from the oximetry tracings. Need for supplemental O₂, nursing/ respiratory interventions, and complications were recorded. Records were reviewed for the type and duration of surgery and anesthesia, net fluid balance, narcotic / sedative use, demographics and co-morbidities.

Results: Seven of 38 subjects (18.4%) spent at least 30 minutes with SpO₂ <90% during the night (hypoxic group=HG) on their prescribed PAP therapy. The severity of baseline OSA (total and supine apnea-hypopnea index), pre-CPAP SpO₂ (asleep on diagnostic PSG and awake evening after surgery), net fluid balance, and total IV narcotic dose were associated with the HG. Nursing interventions and addition of O₂ were more common in the HG, though other adverse events were not. Review of the oximetry tracings suggested 71% of the HG, and 42% of the non-hypoxic group, had findings of uncontrolled sleep apnea.

Conclusions: Despite the use of prescribed PAP therapy the night following surgery, some OSA patients become hypoxic. Postoperative oximetry monitoring may be indicated in PAP-treated OSA patients undergoing surgery