Xenon offers stable haemodynamics independent of induced hypothermia after hypoxia–ischaemia in newborn pigs

To assess the effect of 18hours (h) 50% xenon (Xe) inhalation at normothermia (NT, 38.5°C) or hypothermia (HT, 33.5°C) on mean arterial blood pressure (MABP), inotropic support and heart rate (HR) following an induced perinatal global hypoxic-ischaemic insult (HI) in newborn pigs. Methods: Newborn pigs ventilated under inhalational anaesthesia, following a 45 minute HI (inhaled oxygen fraction reduced until amplitude integrated electroencephalogram 10minutes) was treated sequentially with 2x10ml/kg saline, dopamine, norepinephrine, hydrocortisone if required. Results: Xenon maintained higher MABP during HT (5.1mmHg, 95%CI 2.34, 7.89), rewarming (10.1mmHg, 95%CI 6.26, 13.95) and after cessation (4.1mmHg, 95%CI 0.37, 7.84) independent of HT, inotropic support and acidosis. Xenon reduced the duration of inotropic support by 12.6h, (95%CI 5.5, 19.73). Inotropic support decreased the HR reduction induced by HT from 9 bpm/C to 5 bpm/C during cooling and from 10-7 bpm/C to 4-3 bpm/C during rewarming. There was no interaction between xenon, HT, inotropic support and acidosis. Xenon during HT cleared lactate faster; 3h post HI median (IQR) values of ((XeHT) 2.8mmol (0.9, 3.1) vs (HT) 5.9mmol/L (2.5, 7.9), p =0.0004). Conclusion: Xenon maintained stable blood pressure reducing the inotropic support requirements during and after administration independently of induced hypothermia – current neonatal encephalopathy treatment. Xenon may offer haemodynamic benefits in clinical neuroprotection studies.