Therapeutic hypothermia: surgical infant with neonatal encephalopathy

Seventy-two hours of therapeutic hypothermia (HT) with a core temperature of 33.5–34.5 C commenced within 6 h of life is becoming the standard of care aiming to reduce death ⁄disability after neonatal encephalopathy (NE) (1–3). As a result of concerns about maintaining haemodynamic stability and normal clotting during surgery, and post-operative wound healing (4), infants with NE born with major congenital abnormalities requiring surgery were excluded in the HT trials. In the UK, infants undergoing HT since the end of total body hypothermia (TOBY) trial are registered into the TOBY registry and managed using a standardized protocol (5). There is no previous report of undertaking surgery in an encephalopathic infant during therapeutic HT. We report our first infant with NE and oesophageal atresia and tracheoesophageal fistula (TEF) who underwent surgery while undergoing therapeutic HT. A 29-year old gravida three para one mother with adequately controlled diabetes mellitus and asthma, noted to have polyhydramnios and foetal unilateral severe hydronephrosis and possible TEF in antenatal scans, delivered a male baby at 39 + 3 weeks gestation, weighing 3340 g by emergency caesarean section following foetal distress, poor cardiotocograph (CTG) trace and ante partum haemorrhage. He needed resuscitation and satisfied the NE inclusion criteria for HT [cord pH: 6.92, base deficit: 16 mmol ⁄L, ventilated, hypotonic and encephalopathic and moderately abnormal amplitude integrated electroencephalography (aEEG) (Fig. 1)]. He was then diagnosed with TEF needing imminent surgery, as well as a ventricular septal defect (VSD). As congenital malformation was a relative contraindication for HT, the benefits over risks were weighed with the surgical team, and HT was commenced after discussion with the parents. At 1.5 h, therapeutic HT was initiated using gloves filled with cold water placed around his head and body and external heating was turned off. At 3.5 h, the rectal temperature (Trec) was 34 C and the infant was transferred to surgery (Fig. 1). HT [Trec (33.1–34 C) (Fig. 1)] was then maintained by not actively warming (passive HT) until returning to neonatal intensive care unit (NICU) after 7 h of surgery. Anaesthesia was induced and maintained with isoflurane (0.86–0.97%), atracurium, fentanyl and morphine throughout the 3 h surgery. In our patient, the TEF was connected to the left main stem bronchus rather than the trachea, which is a rare presentation. This was however identified and divided, and an end to end oesophageal anastomosis was performed. There was minimal blood loss and no transfusion was given. During surgery, the mean (SD) end tidal CO2 (ET CO2) was: 4.2 (0.7) kPa and pCO2 was managed by pH stat [mean (SD):6.29 (1.42) kPa] (measured at 37 C), to maintain pCO2 in the normal range when corrected to Trec of 33.5 C (6). There were no arrhythmias. Heart rate, mean arterial blood pressure, oxygen requirement and Trec at HT were stable during surgery and post-surgery as shown in Fig. 1. He was ventilated and electively muscle relaxed with vecuronium for 5 days to protect the oesophageal anastomosis, which was under tension. On arrival back in the NICU, his Trec was 32.8 C. Active cooling was then continued for 72 h using a body wrap circulated with cold water servocontrolled to the Trec set at 33.5 C [Criticool; Medical ThermoRegulation Expertise (MTRE), Yavne, Israel]. Trec was stable at 33.5 ± 0.1 C Abbreviations aEEG, amplitude integrated electroencephalography; FFP, fresh frozen plasma; HT, Hypothermia; MRI, Magnetic resonance imaging; NE, Neonatal encephalopathy; NICU, neonatal intensive care unit; TEF, tracheoesophageal fistula; Trec, rectal temperature. Acta Paediatrica ISSN 0803–5253