Efficacy of synchronized IMV on weaning neonates from the ventilator.

This study evaluated the efficacy of a new patient-triggered ventilator that triggered the patient's inspiratory effort by detecting the change in airflow by means of a 'hot wire' anemometer. This ventilator was used in both the conventional and the synchronized intermittent mandatory ventilation (SIMV) modes in seven neonates. Values for blood gas, spontaneous breathing rate, tidal volume of spontaneous breaths and minute volume were compared in all seven neonates. The resistive work of spontaneous breathing in five neonates, obtained with synchronized intermittent mandatory ventilation was compared with the values obtained using conventional mechanical ventilation on the previous day of weaning from the ventilator. At each the inflation time studied (0.4, 0.3, 0.24 s), all mechanical breath occurred synchronously with infants' inspiratory efforts. The median trigger delay was 80 ms. Oxygenation was improved on the new system compared with the conventional system. Tidal volume of spontaneous breathing and minute volume were increased with SIMV compared with conventional mechanical ventilation, although the resistive work of spontaneous breathing was decreased with SIMV. The tidal volume of spontaneous breaths was more constant with SIMV versus conventional mechanical ventilation. Thus, the airway flow-triggered SIMV may lessen inspiratory muscle fatigue during weaning process. We conclude that the SIMV is useful in weaning neonates from the ventilator.