PATIENT-TRIGGERED VENTILATION DECREASES THE WORK OF BREATHING IN NEONATES

During conventional intermittent mandatory ventilation (IMV) in neonat es, asynchrony between mechanical and spontaneous breaths is frequent. We tested the hypothesis that patient-triggered ventilation (PTV) red uces the work of breathing (WOB) by providing synchronized assistance for each breath. Accordingly, six intubated preterm infants were studi ed at the median postnatal age of 34 days while they were being weaned from mechanical ventilation (MV). Patients were ventilated using the Draeger Babylog 8000 (software #3) and studied in four successive mode s of MV with a constant level of positive end-expiratory pressure. The y were randomly assigned to IMV, PTV with peak inspiratory pressure of either 10 cm H2O (PTV10) or 15 cm H2O (PTV15), and spontaneous ventil ation with continuous positive airway pressure. PTV was achieved in th e assist/control mode. During PTV, infants adapted their pattern of br eathing in response to an increase in tidal volume (median 7.5 ml/kg i n IMV versus 8.2 in PTV10 and 8.5 in PTV15, p < 0.05) by decreasing th eir respiratory rate, thus maintaining minute ventilation (439 ml/min/ kg in IMV versus 422 in PTV10 and 455 in PTV15, NS) and transcutaneous CO2. WOB fell significantly during PTV compared with its level during IMV (0.81 J/L in IMV versus 0.48 and 0.47 during PTV10 and PTV15, res pectively, p < 0.05). Power of breathing decreased in the same proport ions. These results demonstrate that PTV mode allows reduction of the workload imposed on the respiratory muscles.