M P Samuels1, D P Southall. 1. Department of Paediatrics, National Heart and Lung Institute, Brompton Hospital, London.
Abstract
OBJECTIVE: To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure. DESIGN: Uncontrolled clinical trials in infants deteriorating or failing to improve despite standard medical treatment. SETTING: Paediatric and neonatal intensive care units and paediatric wards. PATIENTS: 88 Infants and young children aged 1 day to 2 years with respiratory failure due to bronchopulmonary dysplasia, the neonatal respiratory distress syndrome, bronchiolitis, myopathy, the congenital hypoventilation syndrome, pneumonitis, and postoperative phrenic nerve palsy. At the start of treatment 59 were receiving greater than or equal to 50% inspired oxygen and 40 positive airway pressure ventilation. INTERVENTION: Treatment was provided within purpose built Perspex chambers of appropriate size. The chamber incorporated safe and effective latex neck seals; facilities for access, monitoring, and observation; and a heater to control the ambient air temperature. MAIN OUTCOME MEASURES: Inspired oxygen concentration and carbon dioxide pressure before application of negative extrathoracic pressure and two and 48 hours afterwards; duration of treatment; and final outcome (discharge home or death). RESULTS: While arterial oxygen saturation was maintained at constant values 75 infants showed reductions in inspired oxygen concentrations (range 4-50%, median 15%) two hours after starting treatment and 74 showed reductions at 48 hours (2-79%, median 20%). Of 59 infants who had carbon dioxide pressure measured before and after starting negative extrathoracic pressure, 21 showed a reduction (range 0.6-8.9 kPa, median 2.0), 30 no change (+/- 0.5 kPa), and eight a rise (range 0.6-5.1 kPa, median 2.1). In 28 patients extubation was facilitated, 54 patients were discharged home, where six continued treatment, and 34 died. Treatments lasted for between two and 236 days (median 13 days). CONCLUSION: Negative pressure respiratory support is a non-invasive yet effective treatment for respiratory failure. It may avoid the need for intubation, reduce the pathophysiological consequences of positive airway pressure ventilation, and aid extubation.
OBJECTIVE: To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure. DESIGN: Uncontrolled clinical trials in infants deteriorating or failing to improve despite standard medical treatment. SETTING: Paediatric and neonatal intensive care units and paediatric wards. PATIENTS: 88 Infants and young children aged 1 day to 2 years with respiratory failure due to bronchopulmonary dysplasia, the neonatal respiratory distress syndrome, bronchiolitis, myopathy, the congenital hypoventilation syndrome, pneumonitis, and postoperative phrenic nerve palsy. At the start of treatment 59 were receiving greater than or equal to 50% inspired oxygen and 40 positive airway pressure ventilation. INTERVENTION: Treatment was provided within purpose built Perspex chambers of appropriate size. The chamber incorporated safe and effective latex neck seals; facilities for access, monitoring, and observation; and a heater to control the ambient air temperature. MAIN OUTCOME MEASURES: Inspired oxygen concentration and carbon dioxide pressure before application of negative extrathoracic pressure and two and 48 hours afterwards; duration of treatment; and final outcome (discharge home or death). RESULTS: While arterial oxygen saturation was maintained at constant values 75 infants showed reductions in inspired oxygen concentrations (range 4-50%, median 15%) two hours after starting treatment and 74 showed reductions at 48 hours (2-79%, median 20%). Of 59 infants who had carbon dioxide pressure measured before and after starting negative extrathoracic pressure, 21 showed a reduction (range 0.6-8.9 kPa, median 2.0), 30 no change (+/- 0.5 kPa), and eight a rise (range 0.6-5.1 kPa, median 2.1). In 28 patients extubation was facilitated, 54 patients were discharged home, where six continued treatment, and 34 died. Treatments lasted for between two and 236 days (median 13 days). CONCLUSION: Negative pressure respiratory support is a non-invasive yet effective treatment for respiratory failure. It may avoid the need for intubation, reduce the pathophysiological consequences of positive airway pressure ventilation, and aid extubation.