Inspiratory and expiratory times for infants ventilator-dependent beyond the first week.
The aim of this study was to determine optimum inspiratory and expiratory times to be used for ventilation of infants older than one week of age. Each infant was studied at a rate of 30 breaths/min (inspiratory times (TI) of 1.0, 0.67 and 0.5 s with expiratory times (TE) of 1.0, 1.33 and 1.5 s, respectively) and at a rate of 60 breaths/min (TI 0.5, 0.33 and 0.25 s and TE 0.5, 0.67 and 0.75 s, respectively). Arterial blood-gases were examined after 20 min on each setting. Fifteen infants with a median gestational age of 27 weeks were studied at a median postnatal age of 9 days and 10 infants with a median gestational age of 27 weeks at a median postnatal age of 24 days. All infants had type I chronic lung disease. Oxygenation did not consistently improve as TI was prolonged, elevating mean airway pressure but, particularly in older infants, was better at TI > or = 0.5 s compared with TI < 0.5 s. In both groups, carbon dioxide elimination was better at 60 than at 30 breaths/min. Thus we suggest that in infants fully ventilator-dependent beyond the first week of life, an inspiratory and expiratory time of 0.5 s should be used as the first choice.
Chan
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V
Department of Child Health, King's College Hospital, London, UK.
Greenough
A
A
D006801:Humans; D007231:Infant, Newborn; D012121:Respiration, Artificial / Q000379:methods*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology* / Q000628:therapy; D015656:Respiratory Mechanics; D013997:Time Factors