PULMONARY MECHANICS DURING GENERAL-ANESTHESIA - INFLUENCE OF MECHANICAL IRRITATION ON THE AIRWAY

The changes in pulmonary resistance (RL) and compliance (CL) following airway irritation and surgical stimulation were investigated in 19 anesthetized, paralyzed patients. Thirteen were normal while 6 had objective evidence of chronic obstructive pulmonary disease (COPD). Broncho-carinal irritation with a suction catheter produced a 27% increase in RL (0.58 .+-. 0.32 kPa [Pascal] l-1 s to 0.74 .+-. 0.40, P < 0.01) and a 10% decrease in CL (0.87 .+-. 0.19 l kPa-1 to 0.81 .+-. 0.22, P < 0.01). These changes were associated with a significant increase in systolic arterial pressure and heart rate during clinical stages of anesthesia (end-tidal enflurane, 1.3 .+-. 0.4%, PaCO2 [arterial CO2 tension] 5.20 .+-. 0.53 kPa). These changes did not correlate with depth of anesthesia but all returned to the pre-irritation value within 5 min. There was no difference in subjects considered normal and those with COPD. Surgical stimulation did not produce significant changes in pulmonary mechanics; repeated broncho-carinal irritation during surgery was associated with a transient increase in RL (P < 0.01).