Tidal Volume Delivery during the Anesthetic Management of Neonates Is Variable.

Abstract

To describe expiratory tidal volume (V_T) during routine anesthetic management of neonates at a single tertiary neonatal surgical center, as well as the proportion of V_T values within the range of 4.0-8.0 mL/kg. A total of 26 neonates needing surgery under general anesthesia were studied, of whom 18 were intubated postoperatively. V_T was measured continuously during normal clinical care using a dedicated neonatal respiratory function monitor (RFM), with clinicians blinded to values. V_T, pressure, and cardiorespiratory variables were recorded regularly while intubated intraoperatively, during postoperative transport, and for 15 minutes after returning to the neonatal intensive care unit (NICU). In addition, paired V_T values from the anesthetic machine were documented intraoperatively. A total of 2597 V_T measures were recorded from 26 neonates. Intraoperative and postoperative transport expiratory V_T values were highly variable compared with the NICU V_T (P < .0001, Kruskal-Wallis test), with 51% of inflations outside the 4.0-8.0 mL/kg range (35% and 38% of V_T >8.0 mL/kg, respectively), compared with 29% in the NICU (P < .001, χ² test). The use of a flow-inflating bag resulted in a median (range) V_T of 8.5 mL/kg (range, 5.3-11.4 mL/kg) vs 5.6 ml/kg (range, 4.3-7.9 mL/kg) using a Neopuff T-piece system (P < .0001, Mann-Whitney U test). The mean anesthetic machine expiratory V_T was 3.2 mL/kg (95% CI, -4.5 to 10.8 mL/kg) above RFM. V_T is highly variable during the anesthetic care of neonates, and potentially injurious V_T is frequently delivered; thus, we suggest close V_T monitoring using a dedicated neonatal RFM.