Effect of Pneumoperitoneum on Functional Residual Capacity
Pneumoperitoneum (PP) during laparoscopic surgery of the abdomen induces a mechanical compression of the diaphragm that reduces the functional residual capacity (FRC). The aim of this study was to evaluate the adverse effect of PP on FRC and the improvement of the degraded FRC using positive end-expiratory pressure (PEEP).
Sixteen patients with normal pulmonary and cardiac functions underwent FRC measurements using an Engström Carestation ventilator with a built-in modified nitrogen washout/washin technique (GE Healthcare). Arterial blood gas analyzes were performed before PP, during PP, and during PP with a PEEP of 5 cmH2O. All patients were anesthetized with propofol and remifentanil and were mechanically ventilated with a tidal volume of 8 mL/kg, a frequency of 10–14 cycles/min, and an FiO2 of 40% using an Engström Carestation. PP increased the intra-abdominal pressure (IAP) to 9 mmHg.
The Engström Carestation easily measured the FRC in patients receiving mechanical ventilation at bedside. PP significantly (p < 0.05) decreased the FRC and PaO2 from 1,833 (1,300–2,112) mL to 1,573 (1,302–2,022) mL and from 173 (155–191) mmHg to 151 (135–165) mmHg, respectively. In contrast, a PEEP of 5 cmH2O significantly (p < 0.05) increased the FRC and PaO2 to 1,861 (1,578–2,273) mL and 165 (137–170) mmHg, respectively.
PP decreased the FRC, which was improved by PEEP. The reduction in the FRC and the decrease in arterial oxygenation were not correlated.
KeywordsChronic Obstructive Pulmonary Disease Arterial Oxygenation Functional Residual Capacity Peak Inspiratory Pressure Closing Volume