ABSTRACT
OBJECTIVE: To assess the haemodynamic consequences of cord clamping (CC) in healthy term infants. DESIGN: Cohort study. SETTING: Tertiary maternity hospital. PATIENTS: 46 full-term vigorous infants born by caesarean section. INTERVENTIONS: Echocardiography was performed before CC, immediately after CC and at 5 min after birth. MAIN OUTCOME MEASURES: Pulsed wave Doppler-derived cardiac output and the pulmonary artery acceleration time indexed to the right ventricle ejection time were obtained. As markers of loading fluctuations, the myocardial performance indexes and the velocities of the tricuspid and mitral valve annuli were determined with tissue Doppler imaging. Heart rate was derived from Doppler imaging throughout the assessments. RESULTS: Left ventricular output increased throughout the first minutes after birth (mean (SD) 222.4 (32.5) mL/kg/min before CC vs 239.7 (33.6) mL/kg/min at 5 min, p=0.01), while right ventricular output decreased (306.5 (48.2) mL/kg/min before vs 272.8 (55.5) mL/kg/min immediately after CC, p=0.001). The loading conditions of both ventricles were transiently impaired by CC, recovering at 5 min. Heart rate progressively decreased after birth, following a linear trend temporarily increased by CC. The variation in left ventricular output across the CC was directly correlated to the fluctuation of left ventricular preload over the same period (p=0.03). CONCLUSIONS: This study illustrates the cardiovascular consequences of CC in term vigorous infants and offers insight into the haemodynamic transition from fetal to neonatal circulation in spontaneously breathing newborns. Strategies that aim to enhance left ventricular preload before CC may prevent complications of perinatal cardiovascular imbalance.
ABSTRACT
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 EtCO2 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.
