Abstracts and Programme: European Society of Anaesthesiologists; 9th Annual Meeting with the Swedish Society of Anaesthesiology; Gothenburg, Sweden, 7-10 April 2001: Respiration
Background and goal of the study: High peak airway pressures are responsible for acute lung injury in a number of species . PCV is claimed to decrease peak airway pressure (Ppeak) in ARDS patients and during general anaesthesia. One-lung ventilation (OLV), lateral decubitus position and thoracotomy lead to a decrease in the respiratory system compliance and may increase airway pressures. The aim of this prospective study was to compare PCV to VCV in OLV during thoracotomy.
Materials and methods: After informed consent, 40 patients consecutively scheduled for thoracotomy in the lateral decubitus position under general anaesthesia and OLV were enrolled. The double-lumen endotracheal tubes were Broncho-Cath® from Mallinckrodt. The first patients received successively VCV then PCV (n = 20), the next patients received the inverse ventilatory sequence (n = 20). Each patient was his own referee. The ventilatory settings (Kion®, Siemens) were identical between both groups: tidal volume (Vt) at 10 mL kg−1, respiratory rate at 12 C min−1, I/E ratio at 1/1 and end expiratory pressure at 0 cmH2O. After 20 min in each mode, Ppeak (cmH2O), arterial pressure in O2 (PaO2, mmHg), heart rate (hr, beat min−1) and mean arterial pressure (MAP, mmHg) were analysed. Preoperative forced expired volume in 1 s (FEV1) and body mass index (BMI) were registered. Data (mean ± SD) were statistically analysed using a Student test, ANOVA and linear regression. Significance was defined by P < 0.05.
Results: Demographic data were identical in both groups. There was no effect linked to the chronological order of both ventilatory modes. Ppeak was 18 ± 8% (5.83 ± 3.30 cmH2O) lower in the PCV mode when compared to the VCV mode (P < 0.0001). PaO2, MAP and hr were not different in both modes. There was no correlation between FEV1, BMI and the extent of drop of Ppeak in the PCV mode.
Conclusions: when compared to VCV in OLV during thoracotomy, PCV allowed a reduction of 18 ± 8% in Ppeak at the same Vt and without deleterious effects on haemodynamics. This may reflect the environment of gas distribution and lung mechanics generated by the ventilator in the PCV mode. In this way, PCV may be a protective form of one-lung ventilation during anaesthesia for thoracic surgery.
1 Slutsky A, Tremblay L. Am J Respir Crit Care Med
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