Objective To determine respiratory rate (RR), tidal volume (TV) and end-tidal carbon dioxide (EtCO2) 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 EtCO2 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 2 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 EtCO2 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.