Work of breathing in anesthetized infants increases when a breathing system filter is used

Background : There are concerns that the inclusion of a pediatric heat and moisture exchange filter (HMEF) is in a breathing system may cause an unacceptable increase in the work of breathing. This study is the first study to objectively measure the increase in work of breathing in the infant population when an HMEF is added to the pediatric breathing circuit.

Methods : Ten patients weighing 3–8 kg were studied in a randomized crossover trial. Work of breathing was analyzed using the integral of pressure–volume loops.

Results : The median increase in the work of breathing associated with the addition of an HMEF was 279 mJ·min⁻¹ (95% CI, 165–903 mJ·min⁻¹). This equates with a percentage increase of 43% (95% CI, 25–138%).

Conclusions : Because of the substantial increase in the work of breathing with an HMEF attached to the tracheal tube, consideration should be given to alternative means of humidification and filtration during periods of spontaneous ventilation in small infants.