Feasibility and safety of passive cooling in a cohort of asphyxiated newborn infants.

OBJECTIVE: Therapeutic hypothermia has become a standard neuroprotective treatment in term newborn infants following perinatal asphyxia. Active cooling with whole body surface or head cooling is complex, expensive and often associated with initial hypothermic overshoot. We speculated that passive cooling might suffice to induce and maintain hypothermia. METHODS: We analysed 18 asphyxiated term newborns treated with hypothermia in three tertiary neonatal and paediatric intensive care units. Target temperatures of 33.5 °C or 33.0 °C were induced and maintained by turning off the heating system of the open neonatal care unit and by using analgesics and sedatives. We compared our results with matching published data from the hypothermia trial of the National Institute of Child Health and Human Development (NICHD) neonatal research network. RESULTS: Four infants required no active cooling at all during the whole cooling period. The other 14 infants had passive cooling during 85% of the total cooling time, and active cooling with ice packs in 15% of the total cooling time. Overshoot was smaller in the present study than in the NICHD study. CONCLUSION: Passive cooling for asphyxiated newborns appears to be feasible for induction and maintenance of hypothermia with a lower risk of overshoot.

Respiratory distress syndrome in near-term babies after caesarean section.

OBJECTIVE: Severe respiratory distress syndrome (RDS) caused by surfactant deficiency is described not only in preterm infants but also in (near-) term babies after caesarean section (CS), especially when carried out before the onset of labour. The aim of the present study was to document the severity of this theoretically avoidable entity in order to improve obstetric and perinatal care. PATIENTS: All neonates admitted to the paediatric intensive care unit of the University Hospital of Bern between 1988 and 2000 with RDS on the basis of hyaline membrane disease (HMD) needing mechanical ventilation (MV) after CS and with a birthweight > or = 2500 g were analysed. HMD was diagnosed when respiratory distress and the typical radiological signs were present. Patients were grouped into elective CS before onset of labour and before rupture of membranes (group 1, n = 34) and patients delivered by emergency CS or CS after onset of labour or rupture of membranes (group 2, n = 22). Analysed indices for severity of illness were duration of stay in intensive care unit and MV, ventilation mode, worst oxygenation index (OI), presence of pulmonary air leak, and systemic hypotension. RESULTS: Mean gestational age (GA) was 37 2/7 weeks in group 1 and 36 2/7 weeks in group 2; no patient had a GA of > or = 39 0/7 weeks. Duration of MV was 4.4 days in group 1 and 3.9 days in group 2. Thirteen patients (38%) of group 1 and 7 (32%) of group 2 had to be managed by rescue high-frequency ventilation. A total of 7 patients had an OI>40. Eight patients (24%) in group 1 and 4 (18%) in group 2 developed a pulmonary air leak. Fourteen neonates (41%) in group 1 had to be supported by catecholamines versus 5 (22%) in group 2. There was one death in group 1. CONCLUSION: Severe RDS on the basis of HMD can also occur in near-term babies after CS; even a fatal outcome can not be excluded. The severity of illness in elective CS without labour may be quite high and is comparable to newborns delivered by CS (after onset of labour and/or rupture of the membranes) who were 1 week younger. No case of HMD was found in our population when CS was carried out after completion of 39 post-menstrual weeks of gestation.

Delayed postischemic hypothermia improves long-term behavioral outcome after cerebral hypoxia-ischemia in neonatal rats.

Hypothermia may be an ideal neuroprotective intervention in hypoxic-ischemic encephalopathy after perinatal asphyxia. The present study describes the long-term effects of prolonged resuscitative whole-body hypothermia initiated 2 h after hypoxic-ischemic injury on brain morphology and neuropsychological behavior in 7-d-old rats. After right common carotid artery ligation and exposure to hypoxia of 8% O(2) for 105 min, 10 animals were kept normothermic at 37 degrees C and 10 animals were cooled to 30 degrees C rectal temperature for 26 h, starting 2 h after the hypoxic-ischemic insult. All hypoxic-ischemic animals were gavage fed to guarantee long-term survival. Neuroprotection was evaluated by magnetic resonance imaging and behavioral testing. Hypothermia significantly reduced the final size of cerebral infarction by 23% at 6 wk after the insult. The most extended tissue rescue was found in the hippocampus (21%, p = 0.031), followed by the striatum (13%, p = 0.143) and the cortex (11%, p = 0.160). Cooling salvaged spatial memory deficits verified at 5 wk of recovery with Morris Water Maze test; whereas circling abnormalities after apomorphine injection and sensory motor dysfunctions on rotating treadmill improved, yet did not reach statistical significance. When compared with controls, hypoxic-ischemic animals performed worse in all behavioral tests. Hypothermia did not influence functional outcome in controls. Significant correlations between behavioral performance and corresponding regional brain volumes were found. We conclude that 26 h of mild to moderate resuscitative hypothermia leads not only to brain tissue rescue, but most important to long-lasting behavioral improvement throughout brain maturation despite severity of injury and delayed onset of cooling.