Key hemodynamic parameters during induced hypothermia cooling phase in healthy and injured piglets

Hypoxic-ischemic encephalopathy (HIE) in newborns treated with therapeutic hypothermia(TH) represents a challenge, especially during cooling phase which could be less controlled. This study explored the hemodynamic effects of the cooling phase of TH in a piglet model of perinatal asphyxia with lung injury. Cardiovascular parameters, including systemic arterial pressure (SAP), pulmonary artery pressure (PAP), heart rate (HR), and cardiac output (CO) were monitored from 38.5 to 39.5°C -physiological- to 31.0°C. The piglets were divided into TH without (H, n = 12) and TH with lung injury (Hi, n = 7). Both groups showed decreases in SAP, HR, and CO, more pronounced in Hi. PAP was consistently higher in Hi, though it decreased significantly below 33.5°C (40 % less at 31°C, compared to baseline). Myocardial contractility decreased along the cooling, particularly in Hi group, explaining CO reduction (40 % and 35 % in Hi and H group, respectively). No significant changes were observed in brain monitoring, oxygen extraction ratio, or acid-base status. We concluded that in HIE model, close hemodynamic monitoring during the induction phase of TH as well as monitoring of tissue oxygenation warrants detection of changes, a special challenge when lung injury is developed. Although hemodynamic changes were observed with TH in this model, it was not contraindicated since brain oxygenation was unchanged. These data suggest that TH may be a viable option for human neonates with similar conditions, but further research is essential to evaluate its safety and efficacy in this vulnerable population.