Issn Print: 0265-0215

Publication Date: 2004/06/01


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Pressure Support Ventilation versus Pressure Controlled Ventilation with the proseal laryngeal mask airway: a randomised comparative and prospective study of anesthetized adult patients: A-273

N. Bernard; S. Bringuier-Branchereau; X. Capdevila

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Background and Goal of Study: During general anesthesia, Pressure Support Ventilation (PSV) could be an alternativesssss to conventional modes of mechanical ventilation. This ventilatory mode is not very used in operating theaters. Its advantages must be defined.
Materials and Methods: After ethical committee approval and informed consent, 30 patients scheduled for orthopedic surgery were included. Peripheral nerve block (PNB) and general anesthesia (GA) were used. GA was induced with sevoflurane (8%) during spontaneous breathing (SB) and sufentanyl (10 μg) and the proseal LMA was inserted. GA was maintained with sevoflurane expiratory fractions allowing BIS scores between 50 and 55 in O2/N2O 50%. Patients were randomly allocated into 2 groups according to the peroperative ventilatory mode (FelixTM, Taema, France): PSV (n = 15, inspiratory trigger = 0.1, expiratory trigger = 3 l/min, Ti max = 1.3sec, minimal RR = 5/min) or CPV (n = 15, RR = 12/min, I/E = 1/2). PSV or CPV pressure levels were adaptated to maintain a Vt at 6-8 ml/kg and EtCO2 at 30-35 mm Hg. Inspiratory pressures, RR, Vt, VE, sevoflurane IF and EF, Ti/Ttot, EtCO2, BIS values, HR and BP at 1, 5 and 10min, and then every 10min were noted. At the end of the surgical procedure, sevoflurane was stopped and the patient was turned to an open circuit at FiO2 1. We measured times to obtain SB, eyes opening (EO) and proseal removal by the patient himself.
Results and Discussions: There was no significant difference between both groups for patients characteristics, surgery durations, Ti/Ttot, VE, Inspiratory Pressure and BIS values. PetCO2 values were significantly increased in PSV group for every times but stayed between 30 and 35 mm Hg in both group. The sevoflurane IF (at 10, 40 and 50 min) and EF (for every times) were significantly decreased in PSV group versus PCV (p < 0.05). Median values of time to obtain SB (50 vs 170 sec, p < 0.001, EO (4min 15 vs 7min 30, p < 0.001) and proseal removal (4min 50 vs 7 min 50, p < 0.001) were significantly decreased in PSV group.
Conclusion(s): PSV can be used in operative rooms when PNB was associated to GA and leads to a faster recovery. This ventilatory mode allows a decrease in the sevoflurane EF and IF during GA for the same BIS level.
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