How to ventilate preterm infants with lung compliance close to circuit compliance: real-time simulations on an infant hybrid respiratory simulator

Abstract

Circuit compliance close to lung compliance can create serious problems in effective and safe mechanical ventilation of preterm infants. We considered what ventilation technique is the most beneficial in this case. A hybrid (numerical–physical) simulator of infant respiratory system mechanics, the Bennett Ventilator and NICO apparatus were used to simulate pressure-controlled ventilation (PC) and volume-controlled ventilation with constant flow (VCVCF) and descending flow (VCVDF), under permissive hypercapnia (PHC) (6 ml kg−1) and normocapnia (SV) (8 ml kg−1) conditions. Respiratory rate (RR) was 36 or 48 min−1 and PEEP was 0.3 or 0.6 kPa. Peak inspiratory pressure (PIP), mean airway pressure (MAP), and work of breathing by the ventilator (WOB) were lower (P < 0.01, 1 − β = 0.9) using the PHC strategy compared to the SV strategy. The WOB increased (P < 0.01; 1 − β = 0.9) when the RR increased. The PC, VCVCF, and VCVDF modes did not differ in minute ventilation produced by the ventilator (MVV), but the PC mode delivered the highest minute ventilation to the patient (MVT) (P < 0.01; 1 − β = 0.9) at the same PIP, MAP, and WOB. The most beneficial ventilation technique appeared to be PC ventilation with the PHC strategy, with lower RR (36 min−1).