CONTINUOUS TRACHEAL GAS INSUFFLATION ENABLES A VOLUME REDUCTION STRATEGY IN HYALINE-MEMBRANE DISEASE - TECHNICAL ASPECTS AND CLINICAL-RESULTS

Objective: Instrumental dead space wash-out can be used to improve car bon dioxide clearance. The aim of this study was to define, using a be nch test, an optimal protocol for long-term use, and to assess the eff icacy of this technique in neonates. Design: A bench test with an arti ficial lung model, and an observational prospective study. Dead space wash-out was performed by continuous tracheal gas insufflation (CTGI), via six capillaries molded in the wall of a specially designed endotr acheal tube, in 30 preterm neonates with hyaline membrane disease. Set ting: Neonatal intensive care unit of a regional hospital. Results: Th e bench test study showed that a CTGI flow of 0.5 l/min had the optima l efficacy-to-side-effect ratio, resulting in a maximal or submaximal efficacy (93 to 100 %) without a marked increase in tracheal and CTGI circuit pressures. In the 30 newborns, 15 min of CTGI induced a signif icant fall in arterial carbon dioxide tension (PaCO2), from 45 +/- 7 t o 35 +/- 5 mmHg (p = 0.0001), and in 14 patients allowed a reduction i n the gradient between Peack inspirating pressure and positive end-exp iratory pressure from 20.8 +/- 4.6 to 14.4 +/- 3.7 cmH(2)O (p < 0.0001 ) while keeping the transcutaneous partial pressure of carbon dioxide constant. As predicted by the bench test, the decrease in PaCO2 induce d by CTGI correlated well with PaCO2 values before CTGI (r = 0.58, p < 0.002) and with instrumental dead space-to-tidal volume ratio (r = 0. 54, p < 0.005). Conclusion: CTGI may be a useful adjunct To convention al ventilation in preterm neonates with respiratory disease, enabling an increase in CO2 clearance or a reduction in ventilatory pressure.