Respiratory adaptation in term infants following elective caesarean section.

Objective: To determine respiratory rate (RR), tidal volume (TV) and end-tidal carbon dioxide (EtCO) values in full-term infants immediately after caesarean section, and to assess whether infants that develop transient tachypnoea of the newborn (TTN) follow the same physiological patterns.

Design And Patients: A Respironics NM3 Monitor (Philips, Netherlands) continuously measured RR, TV and EtCO for 7 min in infants >37 weeks' gestation following elective caesarean section (ECS). Monitoring was repeated at 2 hours of age for 2 min. Gestation, birth weight, Apgar scores and admissions to neonatal unit were documented.

Setting: The operative delivery theatre of Cork University Maternity Hospital, Ireland.

Results: There were 95 term infants born by ECS included. Median (IQR) gestation was 39 weeks (38.2-39.1) and median (IQR) birth weight 3420 g (3155-3740). Median age at initiation of monitoring was 26.5 s (range: 20-39). Data were analysed for the first 7 min of life. Mean breaths per minute (bpm) increased over the first 7 min of life (44.31-61.62). TV and EtCO values were correlated and increased from 1 min until maximum mean values were recorded at 3 min after delivery (5.18 mL/kg-6.44 mL/kg, and 4.32 kPa-5.64 kPa, respectively). Infants admitted to the neonatal unit with TTN had significantly lower RRs from 2 min of age compared with infants not admitted for TTN.

Conclusions: TV and EtCO values are correlated and increase significantly over the first few minutes following ECS. RR increases gradually from birth, and rates were lower in infants that develop TTN.