EFFECTS OF NEBULIZED SALBUTAMOL ON RESPIRATORY MECHANICS IN ADULT-RESPIRATORY-DISTRESS-SYNDROME

Objective. To determine whether nebulized salbutamol improves the resp iratory mechanics of patients with adult respiratory distress syndrome (ARDS). We also assessed the mechanisms that contribute to high respi ratory system resistances during this disease. Patients and setting. E leven consecutive patients with ARDS without clinical evidence of chro nic obstructive pulmonary disease, admitted to a polivalent intensive care unit, and mechanically ventilated with Siemens Elema Servo C vent ilator at constant inspiratory flow. Method: Peak airway pressure (Ppe ak), airway pressure immediately after end inspiratory occlusion (P1), plateau pressure (P2) and intrinsic positive end-expiratory pressure (PEEPi) were measured at baseline condition and then 5, 15, and 30 min after 1 mg of salbutamol had been administered via a nebulizer throug h the endotracheal tube. Partial pressure of arterial oxygen (PaO2), h eart rate (HR) and mean blood pressure (BP) were monitored and minimal respiratory system resistances (Rrs,m), additional resistances (DRrs) and static compliance (Cst) were computed Results. Between baseline a nd post-salbutamol, we observed changes in Ppeak, P1, P2, PEEPi and Rr s,m. As there were no significant differences between values at the di fferent intervals during post administration, the results are describe d comparing baseline and 15 min post-salbutamol administration values. We found a significant decrease in Ppeak (4.9 +/- 0.8 cmH(2)O), P1 (3 +/- 0.6 cmH(2)O), P2 (2.1 +/- 0.6 cmH(2)O), PEEPi (1.9 +/- 0.5 cmH(2) O) and Rrs,m (1.9 +/- 0.3 cmH(2)O/1 s(-1)); DR, rs decreased in five p atients, did not change in four and increased in two. HR, PaO2 and BP did not change. Conclusions: a) Salbutamol administered through the en dotracheal tube by a nebulizer device lessens respiratory system resis tances and airway and alveolar pressures, and therefore could decrease the risk of barotrauma and alveolar damage; b) high respiratory syste m resistances in ARDS have an increased smooth muscle tone component t hat can be reversible with salbutamol.