The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

FLOW-TRIGGERED / FLOW-CYCLED VENTILATION IN CONGENITAL DIAPHRAGMATIC HERNIA PATIENTS: A CASE SERIES

Peter Betit RRT, Daphne Munhall RRT. Barry Grenier RRT, Jay Wilson MD Children's Hospital, Boston, MA.

INTRODUCTION: The trend in ventilation strategies for congenital diaphragmatic hernia (CDH) patients has shifted from the use of muscle paralysis and hyperventilation, to the preservation of spontaneous breathing and permissive hypercapnea^{1}. The objectives of this trend are to provide adequate gas exchange while minimizing ventilator-induced lung injury. In our institution flow-triggered/ flow-cycled ventilation (FTCV) (Bird VIP, Palm Springs, CA), is used to achieve this strategy. We report our experience with FTCV in CDH patients.

SUMMARY: From 3/93 to 3/96, FTCV was utilized in 36 CDH patients, mean weight 3.34 ± 0.68 kg. Twelve patients were managed with FTCV following ECMO and 24 did not require ECMO. FTCV was initiated once muscle relaxants and sedatives were reversed and spontaneous breathing resumed. Sedation was titrated to maintain analgesia without compromising respiratory effort. Trigger and cycle thresholds were adjusted to ensure patient/ventilator synchrony. Each triggered breath was supported with an initial \delta P (PiP-PEEP) of 23.06 ± 4.29 cmH_{2}O, which was weaned incrementally. PEEP ranged from 3 to 5 cmH_{2}O and adequate gas exchange was maintained. Mean Vt was 5.24 ± 0.81 ml/kg and mean RR was 53.83 ± 8.05. The total ventilator duration was 20.82 ± 14.21 days with 16.69 ± 10.77 (80.2%) FTCV days. The \delta P at which patients were extubated was 11.12 ± 1.75 cmH_{2}O with a mean Vt of 4.84 ± 1.05 ml/kg. The duration spent at the extubation \delta P was 1.97 ± 1.38 days. Extubation was successful in 34/36 (94.4%) patients. Reintubation was required in 2 patients, one due to upper airway edema and the other due to narcotic-induced hypoventilation. Survival rate was 35/36 (97.2%). One post-ECMO patient died from sepsis. There were no significant differences between post-ECMO and non-ECMO patients with respect to the above parameters except for ventilator duration. The total ventilator duration was 29.17 ± 14.66 days for post-ECMO patients versus 16.27 ± 11.96 days for non-ECMO patients (p = 0.02). DISCUSSION: FTCV enhances patient/ventilator synchrony by providing ventilatory support that allows the patient to regulate Ve and I:E. Periods in which FTCV were not feasible were related to sedation levels that limited spontaneous breathing and were typically during admission, in the immediate post-operative period and following separation from ECMO. The difference in ventilator duration between post-ECMO and non- ECMO patients may be related to the severity of illness. We speculate that the high extubation success rate may indicate that extubation could be attempted earlier and potentially reduce the total ventilator duration and potential complications. We have found FTCV to be well suited for the trend in ventilation strategies for CDH patients.

1. Wung JT, Sahni R, Moffitt ST, Lipsitz E, Stolar CJH. Congenital diaphragmatic hernia: Survival treated with very delayed surgery, spontaneous respiration, and no chest tubes. J Ped Surg. 1995: 30(3); 406-409.

Reference: OF-96-090

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