Effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in anesthetized pigs.

OBJECTIVE

To evaluate the effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in pigs anesthetized to suppress spontaneous breathing.

DESIGN

Prospective, randomized, experimental study.

SETTING

A research laboratory at a university medical center.

SUBJECTS

Eight healthy, anesthetized pigs, weighing 22 to 25 kg.

INTERVENTIONS

Pigs, with and without muscular blockade, were mechanically ventilated during an infusion of sodium pentobarbital that was titrated to suppress spontaneous breathing activity.

MEASUREMENTS AND MAIN RESULTS

No significant differences were observed between pressure/volume curves of the lungs, the chest wall, and the total respiratory system, as determined by inflating and deflating the lungs during anesthesia, with or without neuromuscular blockade, in random order. Functional residual capacity was 985 +/- 87 mL with neuromuscular blockade and 997 +/- 78 mL without neuromuscular blockade (NS). A comparison of the total respiratory system, lung, and chest wall compliances obtained with and without neuromuscular blockade showed high correlations (total respiratory system compliance [r2 = .86]; chest wall compliance [r2 = .83]).

CONCLUSION

Neuromuscular blockade does not alter the elastic properties of the lungs, chest wall, or total respiratory system in mechanically ventilated pigs receiving sodium pentobarbital anesthesia to suppress spontaneous breathing efforts.