CONTINUOUS MONITORING OF VENTILATORY MECHANICS DURING ONE-LUNG VENTILATION

Objective. The Ultima SV respiratory monitor can be used to monitor th e intraoperative effects of the lateral decubitus position and one-lun g ventilation on ventilatory mechanics. Methods. Eight patients with e sophageal cancer who required one-lung ventilation for esophagectomy a nd reconstruction were enrolled in the study We monitored pressure-vol ume or flow-rate-volume loops continuously throughout the operation. R espiratory parameters were evaluated closely during five conditions of ventilation: two-lung ventilation in the supine position, two-lung ve ntilation in the lateral decubitus position, dependent one-lung ventil ation in the lateral decubitus position, nondependent one-lung ventila tion in the lateral decubitus position, and dependent one-lung ventila tion in the lateral decubitus position with the chest opened. Respirat ory rate was controlled at 10 breaths/min, and tidal volume was kept c onstant (10 ml/kg) during surgery. Results. Peak inspiratory pressure increased to 29.0 +/- 9.0 (mean +/- SD) cm H2O in the dependent one-lu ng in the lateral decubitus position with the chest opened (p < 0.01). Dynamic compliance decreased to 29.4 +/- 4.9 ml/cm H2O in the depende nt one-lung in the lateral decubitus position with the chest opened (p < 0.01). The changing configuration of the loops also offered additio nal and instantaneous information during one-lung ventilation. Conclus ions. One-lung ventilation caused several changes in the whole respira tory system (lung, thorax, and endotracheal tube). Continuous monitori ng of flow-rate-volume or pressure-volume loops with in-line spirometr y provided comprehensive information regarding parameters in one-lung ventilation.