Neonatal patterns of breathing after cesarean section with or without epidural fentanyl

Abstract

The pattern of breathing and lung mechanics were evaluated during the first 7 h of life in full-term healthy newborns delivered by cesarean section with bupivacaine epidural anesthesia, without (group 1) or with the addition of 100 μg of fentanyl (group 2). Respiration and oxyhemoglobin saturation (Sp(O2)) were measured with calibrated inductive plethymsography and pulse oximetry, respectively, and recorded from 60-420 min following birth. Compliance of respiratory system (C(RS)) was measured using a multiple occlusion technique at 60 and 420 min. Pattern of breathing was compared during period I (60-240 min) and II (240-420 min) with the following results: 1) the number of apnea spells was similar in both groups during both periods; 2) in both groups, from period I to period II a significant decrease in apnea duration was observed (7.6 ± 0.7 s-4.1 ± 0.5 s in group 1 and 6.7 ± 1.2 s - 5.1 ± 1.0 s in group 2, respectively (P < 0.05); 3) respiratory rate (RR) and minute ventilation (V̇(E)) were similar in both groups during both study periods; and 4) both RR and V̇(E) significantly decreased in the two groups from period I to period II (i.e., 59 ± 5 - 46 ± 2 breath per min-1 and 313 ± 60 - 248 ± 24 ml·kg-1·min-1 in group 2, respectively; P < 0.05). For newborns without apnea breathing room air, Sp(O2) was always greater than 95%, and the lowest Sp(O2) after the occurrence of apnea was never less than 91%. Between both groups, C(RS) were similar at 60 or 420 min but significantly increased in each group (P < 0.05) from 60-420 min (i.e., 0.59 ± 0.19 - 0.72 ± 0.12 ml·kg-1·cmH2O-1 in group 1 and 0.54 ± 0.12 - 0.67 ± 0.14 ml·kg-1·cmH2O-1 in group 2, respectively). The authors concluded that in healthy newborns, no respiratory impairment occurred during the first 7 h of life after cesarean section for which epidural fentanyl had been administered to the mother.