Impaired lung function after intubation and mechanical ventilation for surgical ligation of the ductus arteriosus in preterm infants.

OBJECTIVE: Significant patent ductus arteriosus (PDA) in the preterm infant has been associated with pulmonary edema and impaired gas exchange. Therefore, surgical ligature of the DA may be required. However, the effects of intubation and mechanical ventilation on the PDA-induced lung dysfunction presently are unknown. The aim of the study was to investigate whether intubation and mechanical ventilation alter pulmonary function in the preterm infant with significant PDA. DESIGN: A prospective study. SETTING: The neonatal intensive care unit and department of anesthesiology in a university hospital. PARTICIPANTS: Preterm infants <32 weeks' gestational age treated with nasal continuous positive airway pressure (NCPAP) and requiring mechanical ventilation for undergoing surgical DA ligature. INTERVENTIONS: Respiratory, Doppler echocardiographic parameters, and chest x-ray transparencies of the lungs were measured during NCPAP and 2 hours after intubation and starting mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: Twenty preterm infants (gestational age = 27 ± 1 wk, birth weight = 950 ± 140 g) were included. Heart rate, O(2) need, PaCO(2), and plasma lactate concentrations were significantly higher after intubation. The mean oxygenation index increased from 1.5 ± 0.6 to 7.2 ± 3 (p < 0.05). The overall transparencies of the lungs decreased after intubation. DA diameter, shortening fraction of the left ventricle, left pulmonary artery blood flow velocities, and left atrium/aorta did not change. CONCLUSION: In preterm infants with significant PDA, intubation and mechanical ventilation before surgical DA ligation may increase the O(2) need and PaCO(2) and may promote lung edema formation. Mechanical ventilation-induced impairment in lung function is not associated with a change in pulmonary or systemic circulation or DA flow. Special care should be taken to prevent respiratory failure when intubation and mechanical ventilation are required for undergoing surgical DA ligation in the preterm infant.

Development of a new model to investigate the fetal nociceptive pathways.

OBJECTIVE: The aim of the study was to develop an experimental model to investigate the fetal nociceptive pathways and fetal analgesia. METHODS: We tested the electromyographic (EMG) response from the biceps femoris to electrical stimulation of the sural nerve in chronically-prepared fetal lambs with and without sufentanil. RESULTS: An EMG response could be recorded 140 ms after the electrical stimulation above a threshold of current's intensity. The response presents the characteristics of a nociceptive flexion reflex. The reflex magnitude increased with the stimulus intensity. Sufentanil decreased the response. Bradycardia was noted 10 s after the stimulation and was not observed after sufentanilinfusion. Catecholamine concentrations were not altered by the stimulation. CONCLUSION: Our study shows that a nociceptive flexion reflex can be recorded in the ovine fetus. We suggest that this reflex can be used as a new tool to study the ontogenesis of the nociceptive pathways and the effects of analgesic drugs during fetal life.