CONTINUOUS NEGATIVE EXTRATHORACIC PRESSURE VERSUS POSITIVE END-EXPIRATORY PRESSURE IN PIGLETS AFTER SALINE LUNG LAVAGE

Recent reports have suggested that substituting continuous negative ex trathoracic pressure (CNEP) for positive end-expiratory pressure (PEEP ) may result in clinical benefits to infants with pulmonary disease. O ther studies have suggested potential hemodynamic advantages. We compa red the effects of CNEP and PEEP in 13 mechanically ventilated newborn piglets after acute lung injury induced by saline lavage. The piglets were instrumented, saline-lavaged, and exposed to 15 minute periods o f incremental CNEP (-3, -6, -9, -12 cmH(2)O) (n = 7) or PEEP (3, 6, 9, 12 cmH(2)O) (n = 6). We measured and/or calculated dynamic lung compl iance (C-Ldyn), lung resistance (R(L)), end-expiratory lung volume (EE LV), blood gases, cardiac output (CO), heart rate (HR), transmural vas cular pressures, and pulmonary and systemic vascular resistance. Pulmo nary function abnormalities after saline lavage included decreased P-a O2, C-Ldyn, EELV, and increased P-aCO2 and R(L) (P < 0.05). Except for decreased CO, lung inflation with both CNEP and PEEP resulted in larg e increases in P-aO2 without major pulmonary or hemodynamic effects. O ther than differences in EELV at 3, 6 and 9 cmH(2)O distending pressur e, there were no differences in pulmonary function or hemodynamics bet ween sequences of incremental CNEP and PEEP. We conclude that CNEP and PEEP are physiologically equivalent in this model of acute lung injur y. (C) 1994 Wiley-Liss, Inc.