Lung function in immature baboons with respiratory distress syndrome receiving early caffeine therapy: A pilot study

Aim: The cardiopulmonary effects of early caffeine therapy in surfactant-treated immature baboons were measured. Methods: Nine 125-d (term = 185 d) baboons receiving caffeine citrate at 1 and 12 h age as part of a pilot study on the use of nasal CPAP at 24 h were compared to six untreated animals destined for prolonged ventilator support. All received surfactant prior to their first breath and again at 6 h age. Serial physiologic and ventilatory parameters were recorded. Lung mechanics were measured by body plethysmography. Data were compared from 1 through 24 h age. Results: There were no between-group differences in any study variables prior to caffeine therapy at 1 h age. Airway resistance (R_A) was significantly lower in caffeine-treated compared to non-caffeine-treated animals at 12 and 24 h age [median (range) 12 h: 47 (35-107) cm H₂O/l/s to 135 (120-259) cm H₂O/l/s; and 24 h: 93(60-137) cm H₂O/l/s to 211 (86-235) cm H₂O/l/s; p > 0.05]. Respiratory system compliance (C_RS) was higher in caffeine-treated compared to non-caffeine-treated animals at 18 and 24 h age [median (range) 18 h: 0.60 (0.29-1.58) ml/cm H₂O/kg to 0.39 (0.33-0.46) ml/cm H₂O/kg; and 24 h: 0.68 (0.36-1.20) ml/cm H ₂O/kg to 0.36 (0.33-0.55) ml/cm H₂O/kg; p < 0.05]. Ventilatory efficiency index and arterial/alveolar ratio significantly improved in caffeine-treated animals over the 24-h study period (p < 0.05, repeated measures ANOVA). Conclusions: In this pilot study, early caffeine treatment, combined with prophylactic surfactant therapy, was associated with better lung function during the initial 24 h of life. This combined approach may facilitate earlier extubation or prophylactic efforts to support infants on nasal CPAP. Randomized, controlled investigation is warranted.