Mechanical Power and Energy in Invasively Ventilated Newborn Infants.

Abstract

Mechanical power estimates the amount of energy delivered to ventilated lungs, but there are no available data for neonates. This study aimed to provide a real-world description of power and investigate its relationship with clinical variables in neonates. This was a cross-sectional study enrolling neonates of any gestational age. Patients were classified as recovering from respiratory distress syndrome, affected by neonatal acute respiratory distress syndrome, or with evolving bronchopulmonary dysplasia. Simultaneously collected ventilation and oxygenation data, as well as ultrasound-assessed lung aeration, were used; power was calculated with four different equations. A total of 100 (55 males) neonates (32 with respiratory distress syndrome, 30 with neonatal acute respiratory distress syndrome, 10 with evolving bronchopulmonary dysplasia, and 28 controls with no lung disease) were studied. Distributions of power and energy ( i.e. , power for a single breath) for the whole population were given (median power ranging between (interquartile range [25th, 75th percentile]) 0.28 [0.18, 0.39] and 0.39 [0.29, 0.54] J · min -1 · kg -1 , median energy ranging between 7.1 [4.9, 9.1] and 9.5 [6.8, 12.3] mJ/kg). Median power (difference varying between 0.21 and 0.9 J · min -1 · kg -1 [ P was always less than 0.001], depending on the equation used) and energy (difference varying between 0.9 and 3 mJ/kg [ P was always less than 0.001], depending on the equation used) were higher in neonates with respiratory failure than in controls. Components of power due to dynamic and static strain showed similar differences. Power correlated with oxygenation (adjusted ρ between 0.18 [95% CI, 0.02 to 0.34] and 0.22 [95% CI, 0.06 to 0.38]; P varying between 0.032 and 0.045) and lung aeration impairment (ρ between 0.25 [95% CI, 0.07 to 0.41] and 0.27 (95% CI, 0.08 to 0.43); P varying between 0.009 and 0.013, depending on the equation used). Mechanical power, its components due to dynamic and static strain, and energy are higher in neonates with respiratory disorders than in controls. Mechanical power and its components are correlated with impairment of oxygenation and lung aeration.