Work of breathing during SIMV with and without pressure support.

OBJECTIVE: In a randomised trial, pressure support with synchronised intermittent mandatory ventilation (SIMV) compared to SIMV alone was associated with a significant reduction in supplementary oxygen duration. The hypothesis that the addition of pressure support to SIMV compared to SIMV alone would reduce the work of breathing was examined. DESIGN: Prospective study. SETTING: Perinatal service. PATIENTS: 20 infants, with a mean gestational age of 31 weeks, being weaned from mechanical ventilation were studied. INTERVENTIONS: 1 h periods of SIMV and SIMV with pressure support at 50% of the difference between the peak inflating pressure and positive end expiratory pressures. MAIN OUTCOME MEASURES: The work of breathing was assessed by measurement of the transdiaphragmatic pressure time product (PTPdi). RESULTS: The mean PTPdi on SIMV plus pressure support was 112 cm H(2)Oxs/min, approximately 20% lower than that on SIMV alone (141 cm H(2)Oxs/min) (p<0.001). CONCLUSION: The addition of pressure support to SIMV reduces the work of breathing in infants being weaned from the ventilator.

Does nasal CPAP reduce bronchopulmonary dysplasia (BPD)?

UNLABELLED: Early nasal continuous positive airway pressure (nCPAP) or early surfactant therapy with early extubation onto nCPAP rather than continued mechanical ventilation has been adopted by many centres, particularly in Scandinavia, as part of the treatment of newborns with respiratory distress syndrome. It has been suggested that bronchopulmonary dysplasia is less of a problem in centres adopting such a policy. Results from randomized trials suggest prophylactic or early nCPAP may reduce bronchopulmonary dysplasia (BPD), but further studies are required to determine the relative contributions of an early lung recruitment policy, early surfactant administration and nCPAP in reducing BPD. In addition, the optimum method of generating and delivering CPAP needs to be determined. CONCLUSION: The efficacy of nCPAP in improving long-term respiratory outcomes needs to be compared with the newer ventilator techniques with the optimum and timing of delivery of surfactant administration.