Effect of lung hyperinflation and endotracheal suctioning on heart rate and rhythm in patients after coronary artery bypass graft surgery.

We examined the effect of lung hyperinflation and suction on PaO2, heart rate, and rhythm in patients after coronary artery bypass graft surgery (N = 26). Three lung hyperinflation breaths, at one of five randomly ordered volumes (tidal volume, 12 cc/kg, 14 cc/kg, 16 cc/kg, or 18 cc/kg of lean body weight) were delivered, by a ventilator (fraction of inspired oxygen 1.0), followed by 10 seconds of continuous suction. Lung hyperinflation and suctioning were repeated three times. Repeated-measures analysis of variance revealed a statistically significant increase (p = 0.000) in PaO2 immediately after the third suction pass, which was volume dependent (p = 0.009). A statistically significant (p less than 0.001) increase in heart rate from baseline occurred over the three lung hyperinflation-suctioning sequences that was not volume dependent. The mean increase in heart rate was 6.8 beats/min. The majority of rhythm changes for lung hyperinflation and suctioning were from normal sinus rhythm to sinus tachycardia. Suction was associated with a greater incidence of rhythm (53.9%) and arrhythmia (80.8%) changes. The most frequent arrhythmia was premature atrial contraction.