Cerebral vascular effects of hypovolemia and dopamine infusions: a study in newborn piglets

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Abstract:

Abstract

Aim:  Despite widespread use, effects of volume boluses and dopamine in hypotensive newborn infants remain controversial. We aimed to elucidate if hypovolemia alone impairs cerebral autoregulation (CA) and if dopamine affects cerebral vasculature.

Methods:  In 12 piglets, cerebral perfusion (laser‐Doppler flux) and oxygenation [near‐infrared spectroscopy (NIRS)] were examined during dopamine (20–50 μg/kg per minute) and nonpharmacologically induced blood pressure (ABP) changes. Effect on cerebral perfusion and oxygenation was quantified as frequency gain between ABP and laser‐Doppler flux (gain‐LDF) and NIRS [gain‐oxygenation index (OI)], respectively. Gain quantifies change in perfusion or oxygenation per ABP‐change. CA was estimated as gain‐LDF during nonpharmacologically induced ABP changes, that is, as degree of impairment. Dopamine’s cerebrovascular effect was estimated by contrasting gain during dopamine‐ and nonpharmacologically induced ABP changes. Measurements were conducted during both normovolemia‐ and haemorrhage‐induced hypovolemia.

Results:  Hypovolemia elicited hypotension (p = 0.02) as well as increasing impairment of CA (p = 0.01). However, hypovolemia without hypotension did not affect CA significantly. Dopamine increased perfusion significantly compared to nonpharmacological challenges (mean difference: 1.5%/mmHg, 95% CI: 0.5–2.6, p = 0.007). Oxygenation was, however, similar (mean difference: 0.01 μmol/L per mmHg, 95% CI: −0.03 to 0.05, p = 0.7).

Conclusion:  Our findings do not support that hypovolemia alone impairs CA. Furthermore, dopamine seems to increase cerebral perfusion but not oxygenation.

Document Type: Research Article

DOI: http://dx.doi.org/10.1111/j.1651-2227.2012.02666.x

Affiliations: 1:  Department of Neonatology, Copenhagen University Hospital – Rigshospitalet, Copenhagen, Denmark 2:  Department of Pediatrics, Copenhagen University Hospital – Hvidovre Hospital, Hvidovre, Denmark

Publication date: July 1, 2012

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