Table 1.
Summary of systemic and cerebral effects of inotropic agents.
| Inotropic agent | Mechanism of action | Dose-dependant effects | Changes in CBF (clinical and animal studies) | Changes in cerebral metabolic rate (animal studies) |
|---|---|---|---|---|
| Dopamine | Dose-related action on adrenergic α and β, and dopaminergic receptors | Low dose (0.5–4 μg.kg−1.min−1): renal vasodilation, direct renal tubular effect, positive inotropy | ↑ CBF with ↑ MAP in hypotensive preterm infants (Seri et al., 1993; Jayasinghe et al., 2003; Munro et al., 2004; Pellicer et al., 2005) | Stimulation of cerebral dopaminergic receptors in adult baboons |
| Medium dose (4–10 μg.kg−1.min−1): positive inotropy, vasocontriction | ↑ CBF/cerebral oxygenation in both preterm and term newborn piglets (Ferrara et al., 1995; Nachar et al., 2011) | ↑ cerebral oxygen consumption with ↑ CBF (McCulloch and Harper, 1977) | ||
| High dose (>8–10 μg.kg−1.min−1): positive inotropy and chronotropy | Cerebrovasodilatation with ↑ CBF in adult animal studies (Von Essen, 1974; Myburgh et al., 2002) | |||
| Dobutamine | Relatively selective for cardiac β-1 receptors, with lower affinity for peripheral α-1 and β-2 receptors | Low-medium dose (5–10 μg.kg−1.min−1): positive inotropy and chronotropy, peripheral dilatation | ↑ Superior vena cava flow in preterm infants, no data on CBF (Osborn et al., 2002) | ↑ Systemic oxygen consumption and offset systemic oxygen delivery (Penny et al., 2001) |
| Medium-to-high dose (>10 μg.kg−1.min−1): positive inotropy and chronotropy, vasoconstriction. | ↑ Cerebral oxygenation with ↑ MAP in term newborn piglets (Nachar et al., 2011) | |||
| ↑CBF in term newborn piglets, but not preterm piglets (Ferrara et al., 1995) | ||||
| Adrenaline | Acts on adrenergic α-1, β-1 and β-2 receptors | Low-moderate dose (0.02–0.1 μg.kg−1.min−1): positive inotropy and chronotropy, peripheral (renal and mesenteric) vasodilatation, metabolic effects | ↑ CBF with ↑ MAP in hypotensive preterm infants (Pellicer et al., 2005) | – |
| Moderate-high dose (>0.1 μg.kg−1.min−1): vasoconstriction in addition to effects above | ↑ Cerebral oxygenation with ↑ MAP in newborn piglets (Nachar et al., 2011) | |||
| Noradrenaline | Mainly acts on adrenergic α-1, α-2 receptors | Peripheral vasoconstriction | ↑ Cerebral oxygenation with ↑ MAP in newborn piglets (Nachar et al., 2011) | – |
| Milrinone | Type 3 cAMP phosphor-diesterase inhibitor | Positive inotropy and peripheral vasodilatation | No effect on cerebral oxygenation or MAP in newborn piglets (Nachar et al., 2011) | – |
CBF, cerebral blood flow; MAP, mean arterial pressure.