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The effects of adaptive pressure ventilation–synchronised intermittent mandatory ventilation and pressure-controlled synchronised intermittent mandatory ventilation on pulmonary mechanics and arterial gas analyses during laparoscopic cholecystectomy

Background

Hypercapnia and elevated intraabdominal pressure from carbon dioxide (CO2) pneumoperitoneum can adversely affect respiratory mechanics and arterial blood gases. We tested the hypothesis that adaptive pressure ventilation–synchronised intermittent mandatory ventilation (APV-SIMV) may provide better pulmonary mechanics, CO2 homeostasis and pulmonary gas exchanges with less frequent ventilatory settings (tidal volume (TV), respiratory rate (RR)) and lower peak inspiratory pressure (Ppeak) and plateau pressure (Pplat) than pressure-controlled synchronised intermittent mandatory ventilation (P-SIMV) in patients undergoing laparocopic cholecystectomy (LP).

Method

The study group consisted of 40 patients (APV-SIMV n = 20, P-SIMV n = 20). LP was performed under total intravenous anesthesia. After induction of anesthesia, a RR of 12 breaths/minute, and an inspiratory:expiratory rate of 1:2 and PEEP of 6 cmH2O were set for both groups. APV-SIMV was started with a target TV of 8 ml/kg. P-SIMV was started with the inspiratory pressure (Pins) that will provide 8 ml/kg TV. The settings were changed until target parameters to maintain normocapnia and normoxia were achieved (ETCO2 30–35 mmHg, PaCO2 35–45 mmHg and SaO2 >90%). When the target parameters could not be achieved, the first RR was increased by 2 breaths/minute up to 16 breaths/minute, then the volume or pressure was titrated to induce 1 ml/kg increases in TV up to 10 ml/kg. The initial FiO2 was set to 50%. FiO2 was increased with increments when the SaO2 fell below 90%. PaO2/FiO2, static compliance, VD/VT, Ppeak and Pplat, ETCO2, inspiratory and expiratory resistances, and arterial blood gas analysis were recorded before, during and after pneumoperitoneum. Statistical analysis were carried out using the chi-square test, paired test and independent samples test when appropriate.

Results

Demographic data were similar between groups. Pneumoperitoneum caused significant decreases in static compliance and arterial pH, and increases in Ppeak and Pplat, VD/VT and ETCO2 in both groups. However, APV-SIMV resulted in fewer setting changes, lower peak and plateau pressures, VD/VT, and ETCO2 levels when compared with P-SIMV (P < 0.025).

Conclusion

APV-SIMV may provide better results then conventional P-SIMV in patients undergoing LP.

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Akbaba, M., Tulunay, M., Can, O. et al. The effects of adaptive pressure ventilation–synchronised intermittent mandatory ventilation and pressure-controlled synchronised intermittent mandatory ventilation on pulmonary mechanics and arterial gas analyses during laparoscopic cholecystectomy. Crit Care 11, P164 (2007). https://0-doi-org.brum.beds.ac.uk/10.1186/cc5324

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Keywords

  • Tidal Volume
  • Inspiratory Pressure
  • Plateau Pressure
  • Peak Inspiratory Pressure
  • Target Parameter