Gastrointestinal hemodynamic changes during therapeutic hypothermia and after rewarming in neonatal hypoxic-Ischemic encephalopathy

Abstract

Hypoxic-ischemic encephalopathy (HIE) is associated with disturbances in visceral blood flow velocities. Therapeutic Hypothermia (TH) is a standard of care; however, its impact on gastrointestinal blood flow in infants with HIE is unknown. The objective of this study was to assess gastrointestinal (GI) blood flow and left ventricle output (LVO) in infants with hypoxic-ischemic encephalopathy during whole body TH and after rewarming. Serial echocardiography and Doppler evaluation of intestinal blood flow (celiac (CA) and superior mesenteric (SMA) arteries) were prospectively performed in a cohort of 20 newborn infants with HIE at 4 time points during hypothermia and after rewarming. Demographic, clinical and biochemical data were collected and analyzed for their relevance. Median gestational age and birth weight was 40 weeks (37-41) and 3410g (2190-4950) respectively. Celiac and mesenteric artery flow remained low during hypothermia and rose significantly after rewarming [peak systolic velocity in CA (0.63m/s to 0.77m/s, p=0.004) and SMA (0.43m/s to 0.55m/s, p=0.001)]. This increase was temporally associated with increased left ventricular output (106ml/kg/min to 149ml/kg/min, p<0.0001). Median age to reach 25% of the feeds was 5 days (1-7 days). All patients survived. CA and SMA blood flow velocity and LVO did not vary during hypothermia but rose after rewarming. This may suggest protective effect of therapeutic hypothermia on gastrointestinal system. The association of these physiological changes with neonatal outcome needs further assessment.