Effect of median sternotomy on respiratory system compliance in humans: evaluation without sophisticated instrumentation.

To evaluate the effect of median sternotomy on the static compliance of the respiratory system (C(RS)) in humans, we used a new technique for pressure-volume (PV) curve tracing without sophisticated instrumentation. The accuracy and the reproducibility of the new technique were tested in a lung simulator, while its agreement with multiple-occlusion (MO) technique (the technique most often used in the ICU for C(RS) measurement) was evaluated in 12 mechanically ventilated patients. Finally, the NCI technique was used in 13 cardiosurgical patients to measure C(RS) before and after median sternotomy. Measurements provided by the NCI technique were at least as accurate as standard measurements in the bench study. In ICU patients, we observed a good agreement of C(RS) measurements provided by the two techniques (bias 0.8, 95% limits of agreement -5.6 to 7.2 ml/cm H(2)O) and a similar reproducibility. In cardiosurgical patients we observed a significant (P=0.037) increase in C(RS) with an upward and leftward shift of the PV-curve after median sternotomy. No adverse effect was observed during PV-curve tracing maneuvers. The simplicity of NCI technique allowed for the first time, to our knowledge, PV-curve tracing in humans during cardiosurgery and revealed 5% increase in C(RS) immediately after median sternotomy.