Cerebral Effects of Commonly Used Vasopressor-Inotropes: A Study in Newborn Piglets

Abstract

BackgroundDespite widespread use in sick infants, it is still debated whether vasopressor-inotropes have direct cerebral effects that might affect neurological outcome. We aimed to test direct cerebrovascular effects of three commonly used vasopressor-inotropes (adrenaline, dopamine and noradrenaline) by comparing the responses to those of nonpharmacologically induced increases in blood pressure. We also searched for reasons for a mismatch between the response in perfusion and oxygenation.MethodsTwenty-four piglets had long and short infusions of the three vasopressor-inotropes titrated to raise mean arterial blood pressure (MAP) 10 mmHg in random order. Nonpharmacological increases in MAP were induced by inflation of a balloon in the descending aorta. We measured cerebral oxygenation (near-infrared spectroscopy), perfusion (laser-Doppler), oxygen consumption (co-oximetry of arterial and superior sagittal sinus blood), and microvascular heterogeneity (side stream dark field video microscopy).ResultsVasopressor-inotropes increased cerebral oxygenation significantly less (p≤0.01) compared to non-pharmacological MAP increases, whereas perfusion was similar. Furthermore, cerebral total hemoglobin concentration increased significantly less during vasopressor-inotrope infusions (p = 0.001). These physiologic responses were identical between the three vasopressor-inotropes (p>0.05). Furthermore, they induced a mild, although insignificant increase in cerebral metabolism and microvascular heterogeneity (p>0.05). Removal of the scalp tissue did not influence the mismatch (p>0.05).ConclusionWe demonstrated a moderate vasopressor-inotrope induced mismatch between cerebral perfusion and oxygenation. Scalp removal did not affect this mismatch, why vasopressor-inotropes appear to have direct cerebral actions. The statistically nonsignificant increases in cerebral metabolism and/or microvascular heterogeneity may explain the mismatch. Alternatively, it may simply reflect a vasopressor-inotrope-induced decrease in the arterial-to-venous volume ratio as detected by near-infrared spectroscopy.

A Hemodynamically Significant Patent Ductus Arteriosus Does Not Affect Cerebral or Renal Tissue Oxygenation in Preterm Infants

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External carotid artery flow maintains near infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration

“…We used a fixed 25:75 ratio as a reference for SR-NIRS 24 albeit the optimal reference might depend on both extra-cerebral blood flow and cerebral blood volume. 44 Also, the administered sympathomimetic agents might affect brain microcirculation 45 and we did not perform a CO 2 -correction with the use of ephedrine.…”

A pilot study of cerebrovascular reactivity autoregulation after pediatric cardiac arrest

“…In a piglet model, NIRS accurately measured CBF during epinephrine and dopamine infusions. 16 Epinephrine increased CBF more than dopamine as blood pressure increased, 16 suggesting that dopamine supported autoregulation better than epinephrine. In a piglet model of cardiac arrest, phenylephrine did not affect autoregulation.…”