Ventilatory management during routine general anaesthesia

in European Journal of Anaesthesiology (2009), 26(1), 1-8

Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on the postoperative pulmonary restrictive syndrome in obese patients undergoing gastroplasty.

in CHEST (1997), 111(3), 665-70

STUDY OBJECTIVE: Upper abdominal surgery results in a postoperative restrictive pulmonary syndrome. Bi-level positive airway pressure (BiPAP System; Respironics Inc; Murrysville, Pa), which combines ... [more ▼]

STUDY OBJECTIVE: Upper abdominal surgery results in a postoperative restrictive pulmonary syndrome. Bi-level positive airway pressure (BiPAP System; Respironics Inc; Murrysville, Pa), which combines pressure support ventilation and positive end-expiratory pressure via a nasal mask, could allow alveolar recruitment during inspiration and prevent expiratory alveolar collapse, and therefore limit the postoperative pulmonary restrictive syndrome. This study investigated the effect of BiPAP on postoperative pulmonary function in obese patients after gastroplasty. DESIGN: Prospective controlled randomized study. SETTING: GI surgical ward in a university hospital. PATIENTS: Thirty-three morbidly obese patients scheduled for gastroplasty were studied. INTERVENTION: The patients were assigned to one of three techniques of ventilatory support during the first 24 h postoperatively: O2 via a face mask, BiPAP System 8/4, with inspiratory and expiratory positive airway pressure set at 8 and 4 cm H2O, respectively, or BiPAP System 12/4 set at 12 and 4 cm H2O. Pulmonary function (FVC, FEV1, and peak expiratory flow rate [PEFR]) were measured the day before surgery, 24 h after surgery, and on days 2 and 3. Oxygen saturation by pulse oximeter (SpO2) was also recorded during room air breathing. RESULTS: Three patients were excluded. After surgery, FVC, FEV1, PEFR, and SpO2 significantly decreased in the three groups. On day 1, FVC and FEV1 were significantly improved in the group BiPAP System 12/4, as compared with no BiPAP; SpO2 was also significantly improved. After removal of BiPAP System 12/4, these benefits were maintained, allowing faster recovery of pulmonary function. No significant effects were observed on PEFR. BiPAP System 8/4 had no significant effect on the postoperative pulmonary restrictive syndrome. CONCLUSION: Prophylactic use of BiPAP System 12/4 during the first 24 h postoperatively significantly reduces pulmonary dysfunction after gastroplasty in obese patients and accelerates reestablishment of preoperative pulmonary function. [less ▲]

Comparative evaluation of three heat and moisture exchangers during short-term postoperative mechanical ventilation

in CHEST (1993), 104(1), 220-224

This study compared performance of three heat and moisture exchangers (HME) during short-term postoperative mechanical ventilation. Temperature and absolute humidity (AH) were measured at various points ... [more ▼]

This study compared performance of three heat and moisture exchangers (HME) during short-term postoperative mechanical ventilation. Temperature and absolute humidity (AH) were measured at various points of the ventilatory circuit. There was no statistical difference between the groups, regarding ambient and body To, body weight, fraction of inspired oxygen, tidal volume, and respiratory rate. Only the hygroscopic HME (groups 2 and 3) provide adequate conditioning with regard to AH and To of the inspiratory gases. The performance of hydrophobic HME (group 1) was inferior and appears to be unsatisfactory. Indirect evaluation (variations of inspiratory gases and tracheal temperatures, AH of the expired gases) confirmed the superiority of the hygroscopic HME. These data suggest that humidification of inspiratory gases with a hygroscopic HME is a defensible practice during short-term postoperative mechanical ventilation. Performance of hydrophobic HME may be weak and can expose the patient to an unacceptable risk of endotracheal tube occlusion. [less ▲]