Editor—The results of Sinha and colleagues’ study, showing that volume controlled ventilation was better than time cycled pressure limited ventilation (TCPL), are, at first sight, difficult to explain.1 In both modes, delivered by Bird VIP, the tidal volume was 5–8 ml/kg. Furthermore, the figures indicated almost identical volume and pressure delivery, despite strikingly different flow traces. We therefore investigated this further, using a lung model, by comparing the two ventilation modes via the Bird VIP to TCPL using the SLE 2000 ventilator.

To mimic the illustration in Sinha et al’s study, we used an I:E ratio of 1:1, a rate of 74 breaths per minute, and an inspiratory time of 0.4 seconds. The minimum, weight of infants recruited by Sinha et al was 1200 g, and we would ideally have used a delivered volume of about 7 ml (6 ml/kg).2 Unfortunately, the manufacturer specifies Bird’s minimum volume delivery to …