EFFECTS OF CONTINUOUS (CPAP) AND BI-LEVEL POSITIVE AIRWAY PRESSURE (BIPAP) ON EXTRAVASCULAR LUNG WATER AFTER EXTUBATION OF THE TRACHEA IN PATIENTS FOLLOWING CORONARY-ARTERY BYPASS-GRAFTING

Objective: To evaluate the effects of continuous positive airway press ure (CPAP) and bi-level positive airway pressure (BiPAP) on extravascu lar lung water during weaning from mechanical ventilation in patients following coronary artery bypass grafting. Design: Prospective, random ized clinical study. Setting: Intensive care unit at a university hosp ital. Patients: Seventy-five patients following coronary artery bypass grafting. Interventions: After extubation of the trachea, patients we re treated for 30 min with CPAP via face mask (n = 25), with nasal BiP AP (n = 25), or with oxygen administration via nasal cannula combined with routine chest physiotherapy (RCP) for 10 min (I? = 25). Measureme nts and results: Extravascular lung water (EVLW), pulmonary blood volu me index (PBVI) and cardiac index (CI) were obtained during mechanical ventilation (T1), T-piece breathing (T2), interventions (T3), spontan eous breathing 60 min (T4) and 90 min (T5) after extubation of the tra chea using a combined dye-thermal dilution method. Changing from mecha nical ventilation to T-piece breathing did not show any significant di fferences in EVLW between the three groups, but a significant increase in PBVI from 155 +/- 5 ml/m(2) to 170 +/- 4 ml/m(2) could be observed in all groups (p < 0.05). After extubation of the trachea and treatme nt with BiPAP, PBVI decreased significantly to 134 +/- 6 ml/m(2) (p < 0.05). After treatment with CPAP or BiPAP, EVLW did not change signifi cantly in these groups (5.5 +/- 0.3 ml/kg vs 5.0 +/- 0.4 ml/kg and 5.1 +/- 0.4 ml/kg vs 5.7 +/- 0.4 ml/kg). In the RCP-treated group, howeve r, EVLW increased significantly from 5.8 +/- 0.3 ml/kg to 7.1 +/- 0.4 ml/kg (p < 0.05). Sixty and 90 min after extubation, EVLW stayed at a significantly higher level in the RCP-treated group (7.5 +/- 0.5 ml/kg and 7.4 +/- 0.5 ml/kg) than in the CPAP-(5.6 +/- 0.3 ml/kg and 5.9 +/ - 0.4 ml/kg) or BiPAP-treated groups (5.2 +/- 0.4 ml/kg and 5.2 +/- 0. 4 ml/kg). No significant differences in CI could be observed within th e three groups during the time period from mechanical ventilation to 9 0 min after extubation of the trachea. Conclusions: Mask CPAP and nasa l BiPAP after extubation of the trachea prevent the increase in extrav ascular lung water during weaning from mechanical ventilation. This ef fect is seen for at least Ih after the discontinuation of CPAP or BiPA P treatment.