Effect of Speaking Aloud vs. Positive Expiratory Pressure Therapy on Oxygen Saturation After Abdominal Surgery.

Hypoxia and reduced vital capacity is commonly occurring after abdominal surgery. Positive expiratory pressure is one treatment suggested to improve lung function after surgery, but there is a lack of evidence of effect. En passant, we observed that oxygen saturation was improved when patients talked postoperative day 1. We aim to test whether speaking improves postoperative oxygen saturation and ventilation after abdominal surgery.

It was estimated that a sample size of 34 patients was needed to detect a mean and (SD) difference in oxygen saturation of 1% (2%) and to detect a difference in transcutaneous carbon dioxide partial pressure of 0.5 kPa (1 kPa) with a significance level of 0.05 and a power of 0.8.

In a randomized controlled trial, 50 subjects will be randomized (1:1) to start with either positive expiratory pressure maneuvers, i.e. 3 x 10 deep inspiration followed by expiration in a positive expiratory pressure device of 10-15 cm H20 or to start with reading a text loudly during 3 minutes. Patients will be monitored using Noxturnal T3, Res Med for respiration and pulse oximetry. SenTec Digital Monitoring systems for online transcutaneous carbon dioxide partial pressure measurements.