Changes in Umbilico-Placental Circulation during Prolonged Intact Cord Resuscitation in a Lamb Model

Intact cord resuscitation in newborns with congenital diaphragmatic hernia: insights from a lamb model

Introduction

Congenital diaphragmatic hernia (CDH) is a rare condition characterized by pulmonary hypoplasia, vascular dystrophy, and pulmonary hypertension at birth. Validation of the lamb model as an accurate representation of human CDH is essential to translating research findings into clinical practice and understanding disease mechanisms. This article emphasizes the importance of validating the lamb model to study CDH pathogenesis and develop innovative therapeutics.

Material and methods

At 78 days of gestation, the fetal lamb's left forelimb was exposed through a midline laparotomy and hysterotomy, and a supra diaphragmatic thoracotomy was performed to allow the digestive organs to ascend into the thoracic cavity. At 138 ± 3 days of gestation, lambs were delivered via a cesarean section; then, with umbilical cord intact during 1 hour, the lambs were mechanically ventilated with gentle ventilation in a pressure-controlled mode for 2 h.

Results

CDH lambs exhibited a lower left lung-to-body weight ratio of 5.3 (2.03), p < 0.05, and right lung-to-body weight ratio of 8.2 (3.1), p < 0.05. They reached lower Vt/kg (tidal volume per kg) during the course of the resuscitation period with 1.2 (0.7) ml/kg at 10 min and 3 (1.65) ml/kg at 60 min (p < 0.05). Compliance of the respiratory system was lower in CDH lambs with 0.5 (0.3) ml/cmH2O at 60 min (p < 0.05) and 0.9 (0.26) ml/cmH2O at 120 min (p < 0.05). Differences between pre- and postductal SpO2 were higher with 15.1% (21.4%) at 20 min and 6.7% (14.5%) at 80 min (p < 0.05). CDH lambs had lower differences between inspired and expired oxygen fractions with 4.55% (6.84%) at 20 min and 6.72% (8.57%) at 60 min (p < 0.05). CDH lamb had lower left ventricle [2.73 (0.5) g/kg, p < 0.05] and lower right ventricle [0.69 (0.8), p < 0.05] to left ventricle ratio.

Discussion

CDH lambs had significantly lower tidal volume than control lambs due to lower compliance of the respiratory system and higher airway resistance. These respiratory changes are characteristic of CDH infants and are associated with higher mortality rates. CDH lambs also exhibited pulmonary hypertension, pulmonary hypoplasia, and left ventricle hypoplasia, consistent with observations in human newborns. To conclude, our lamb model successfully provides a reliable representation of CDH and can be used to study its pathophysiology and potential interventions.

Resuscitation with Intact Cord Versus Clamped Cord in Late Preterm and Term Neonates: A Randomized Controlled Trial

OBJECTIVE

To compare the effect of intact cord versus clamped cord resuscitation on the physiologic transition of neonates receiving positive-pressure ventilation (PPV) at birth.

STUDY DESIGN

This open-label, parallel-group, randomized controlled superiority trial was conducted in a tertiary care hospital in India. Neonates born at ≥34 weeks of gestation after a complicated pregnancy or labor were randomized just before birth to receive resuscitation according to the Neonatal Resuscitation Program algorithm with either an intact cord (intact cord resuscitation group) or after early cord clamping (early cord clamping resuscitation group). The allocated study intervention was administered if the neonate needed PPV at birth. The primary outcome was expanded Apgar score at 5 minutes after birth.

RESULTS

Birth weight, gestational age, and the incidence of pregnancy complications were similar in the 2 study groups. The proportion of neonates who received PPV was lower in the intact cord resuscitation group (28.7% vs 36.5%, P = .05; relative risk, 0.79; 95% CI, 0.61-1.01). Among neonates who received PPV, the expanded Apgar score at 5 minutes was significantly higher in the intact cord resuscitation group (median, 15 [IQR, 14-15] vs 14 [IQR, 13-15]; P < .001). The expanded Apgar score at 10 minutes, Apgar scores at 5 and 10 minutes, and oxygen saturation at 1, 5, and 10 minutes were also higher in the intact cord resuscitation group.

CONCLUSION

In late preterm and term neonates, resuscitation with an intact cord results in better postnatal physiologic transition than the standard practice of resuscitation after immediate cord clamping.

TRIAL REGISTRATION

Clinical Trial Registry of India (www.ctri.nic.in); trial registration no. CTRI/2020/02/023379.