Physiologic effects of first-time sitting among male patients after coronary artery bypass graft surgery.

Objective: To study the physiologic effects of sitting among post-operative coronary artery bypass graft (CABG) male patients.
Methods: A prospective, repeated measures non-experimental design was used. Power analysis was used to calculate sample size based on pilot data from 19 subjects. Fifty-five males over the age of 18 years and having first-time CABG surgery were recruited. HR, BP, and SaO2 data were collected from the Marquette bedside monitor. SvO2 was measured by a blood gas sample from the pulmonary artery catheter. Baseline measurements were obtained on all subjects while supine in bed. Measurements were repeated immediately on sitting, after five minutes, after resuming the supine position, and again after 10 minutes.
Results: A repeated-measures ANOVA showed a significant time effect for HR (p < 0.001), SBP (p < 0.001), DBP (p < 0.001), MAP (p < 0.001), and SvO2 (p < 0.001), but not for SaO2.
Conclusions: When post-operative CABG male patients sit on the side of the bed for the first time, they experience an increase in HR and BP. Sitting involves increased oxygen consumption as evidenced by the drop in SvO2. Most patients recover to their baseline levels within 10 minutes of returning to the supine position. Nurses must be cognizant that this routine intervention may not be innocuous. Close monitoring of patients is essential and, with some, a graduated approach to sitting should be considered.