Key words Weaning
Extravascular lung water
Springer Online Journal Archives 1860-2000
Abstract Objective: To evaluate the effects of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP) on extravascular lung water during weaning from mechanical ventilation in patients following coronary artery bypass grafting. Design; Prospective, randomized clinical study. Setting; Intensive care unit at a university hospital. Patients; Seventy-five patients following coronary artery bypass grafting. Interventions; After extubation of the trachea, patients were treated for 30 min with CPAP via face mask (n=25), with nasal BiPAP (n=25), or with oxygen administration via nasal cannula combined with routine chest physiotherapy (RCP) for 10 min (n=25). Measurements and results: Extravascular lung water (EVLW), pulmonary blood volume index (PBVI) and cardiac index (CI) were obtained during mechanical ventilation (T1), T-piece breathing (T2), interventions (T3), spontaneous breathing 60 min (T4) and 90 min (T5) after extubation of the trachea using a combined dye-thermal dilution method. Changing from mechanical ventilation to T-piece breathing did not show any significant differences in EVLW between the three groups, but a significant increase in PBVI from 155±5 ml/m2 to 170±4 ml/m2 could be observed in all groups (p〈0.05). After extubation of the trachea and treatment with BiPAP, PBVI decreased significantly to 134±6 ml/m2 (p〈0.05). After treatment with CPAP or BiPAP, EVLW did not change significantly 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, however, 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 the three groups during the time period from mechanical ventilation to 90 min after extubation of the trachea. Conclusions: Mask CPAP and nasal BiPAP after extubation of the trachea prevent the increase in extravascular lung water during x weaning from mechanical ventilation. This effect is seen for at least 1 h after the discontinuation of CPAP or BiPAP treatment.Further studies have to evaluate the clinical relevance of this phenomenon.
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