Does hypocapnia before and during carbon dioxide insufflation attenuate the hemodynamic changes during laparoscopic cholecystectomy?

BACKGROUND: Hypocapnia before and during carbon dioxide (CO(2)) insufflation for laparoscopic cholecystectomy may reduce the adverse hemodynamic responses. METHODS: After ethical approval, 100 patients scheduled for laparoscopic cholecystectomy were ventilated using a tidal volume of 8 ml/kg, an inspiration:expiration ratio of 1:2.5, and a positive end-expiratory pressure (PEEP) of 5 cm H(2)O. At 15 min before CO(2) insufflation, the patients were randomly allocated into two groups of 50 patients each. For the normocapnia group, the respiratory rate (RR) was adjusted to maintain arterial CO(2) tension (PaCO(2)) at 35 to 45 mmHg. For the hypocapnia group, the RR was adjusted to maintain PaCO(2) at 30 to 35 mmHg. Anesthesia was maintained with sevoflurane 2% to 2.5% in 40% air oxygen and rocuronium. Hemodynamic variables, PaCO(2), end-tidal CO(2) tension (EtCO(2)), arterial-to-end-tidal CO(2) (Pa-ETCO(2)) gradient, and RR were recorded. RESULTS: Compared with the control group, the use of hypocapnia before and during pneumoperitoneum was associated with significantly lower arterial blood pressures, lower PaCO(2) and EtCO(2) values, a higher Pa-ETCO(2), a higher RR (p < 0.001), and less need for supplemental doses of fentanyl and labetalol. CONCLUSION: The authors conclude that the use of hypocapnia before and during CO(2) insufflation is effective in attenuating increases in blood pressure after CO(2) pneumoperitoneum during anesthesia for laparoscopic cholecystectomy.

Comparative study of the non-dependent continuous positive pressure ventilation and high-frequency positive-pressure ventilation during one-lung ventilation for video-assisted thoracoscopic surgery.

The application of volume controlled high-frequency positive-pressure ventilation (HFPPV) to the non-dependent lung (NL) may have comparable effects to continuous positive-airway pressure (CPAP) on the surgical conditions during one-lung ventilation (OLV) for video-assisted thoracoscopic surgery (VATS). After local Ethics Committee approval and informed consent, we randomly allocated 30 patients scheduled for elective VATS after the first 15 min of OLV to ventilate the NL with CPAP of 2 cm H(2)O (NL-CPAP(2)) and HFPPV using tidal volume 2 ml/kg, inspiratory to expiratory ratio <0.3 and respiratory rate 60/min (NL-HFPPV) for 30 min, each in a randomized crossover order. Intraoperative adequacy of surgical conditions was evaluated using a visual analog scale and the changes in hemodynamic and arterial oxygen were recorded. The application of NL-CPAP(2) and NL-HFPPV resulted in more improved arterial oxygenation than during OLV for VATS (P<0.001). The operative field was much better during the application of NL-CPAP(2) than during NL-HFPPV (P<0.001). We concluded that the application of CPAP to the NL during OLV offers good quality of operative field and improved arterial oxygenation for VATS.

Effects of nondependent lung ventilation with continuous positive-pressure ventilation and high-frequency positive-pressure ventilation on right-ventricular function during 1-lung ventilation.

Background. The application of volume-controlled high frequency positive pressure ventilation (HFPPV) to the nondependent lung (NL) may have comparable effects to continuous positive airway pressure (CPAP) on the right ventricular (RV) function, oxygenation, and surgical conditions during one lung ventilation (OLV) for thoracotomy. Methods. After local ethics committee approval and informed consent, 75 patients scheduled for elective thoracotomy using OLV were randomly allocated to receive nondependent lung either CPAP 2 (CPAP2; n=25) or 5 (CPAP5; n=25) cm H2O pressure setting of the device or HFPPV using VT 3 mL-1, I: E ratio <0.3 and R.R 60/min (HFPPV; n=25), followed 15 min of OLV. Intraoperative changes in RV ejection fraction (REF), end-diastolic volume (RVEDVI) and stroke work (RVSWI), stroke volume (SVI), oxygen delivery (DO2), and uptake (VO2) indices and shunt fraction (Qs: Qt) were recorded without any surgical manipulation of the lung. Results. The application of NL-HFPPV resulted in improved REF by 33%, SVI and DO2 (P < 0.01) and reduced RVEDVI, RVSWI, PVRI, oxygen uptake, and shunt fraction by 24.8% (P < 0.01) than in the NL-CPAP groups. Conclusion. We concluded that the use of NL-HFPPV is a feasible option and offers improved RV function and oxygenation during OLV for open thoracotomy.