Is Use of Patient-triggered Ventilation Feasible in Infants? Takeuchi et al. (page 1238)
In seven infants, aged 1–11 months, who had undergone cardiac surgery to repair congenital heart disease, Takeuchi et al. randomly applied five levels of pressure control to determine if patient-triggered ventilation could reduce their respiratory workloads before extubation. Baseline data were obtained when the infants recovered spontaneous breathing in the surgical intensive care unit and met weaning criteria, which included, among other indicators, respiratory rate of less than 50 breaths/min at a backup ventilatory rate of 6 breaths/min and pressure control of 7 cm H2O. Infants were hyperventilated for 2–3 min to lessen their inspiratory efforts, at which time ventilation settings were switched to T1 of 1.5–2 s, respiratory rate of 10 breaths/min, and pressure control of 16 cm H2O. Five levels of pressure control (0, 4, 8, 12, and 16 cm H2O) were applied in random order with assist–control mode. Positive end-expiratory pressure was 3 cm H2O continuous flow at 20 l/min, and, triggering sensitivity, 1.0 l/min. After establishing steady-state conditions, airflow, airway pressure, esophageal pressure (via balloons inserted intranasally), and rib cage and abdominal signals of inductive plethysmography were recorded. No sedatives or opioids were administered during measurements, although fentanyl and midazolam were administered during surgery.
All seven infants were extubated successfully 90 min after completion of the final measurements. After extubation, the research team waited 60 min to confirm that the infants were breathing quietly and then repeated esophageal pressure and rib cage and abdomen signal recording of inductive plethysmography and arterial blood gas analysis. The researchers found that, when the level of pressure control was decreased, tidal volume decreased, respiratory rate increased, and minute ventilation and arterial carbon dioxide tension remained constant. The work of breathing and modified pressure–time product at 4 cm H2O pressure control and after extubation were significantly greater than at pressure control of 16, 12, and 8 cm H2O. Although extrapolation of these results directly to other infant populations is not advised, the authors maintain that pressure-control patient-triggered ventilation with flow triggering could be a feasible strategy for ventilator weaning in infants.