Background Dexmedetomidine (DXM) is a potent, selective a2 adrenoceptor agonist which exerts sedative, neuroprotective, analgesic and anti-inflammatory properties that may be beneficial for neonatal asphyxia. The safety of DXM combined with therapeutic hypothermia is unknown.
Aim To assess safety of low (0.6–1.5mcg/kg/h) and high dose (10mcg/kg/h) DXM with hypothermia as part of a larger study investigating neuroprotection with DXM-augmented cooling.
Methods Following a quantified hypoxic-ischaemic insult, 16 male piglets were randomized to either hypothermia alone (33.5oC from 4–22h, n=7) or DXM plus hypothermia (n=9). Mean arterial blood pressure (MABP) was measured continuously; when MABP was < 40mmHg, a saline bolus was given followed by inotropes. At 48 h the experiment was terminated.
Results There was no difference in baseline variables. Compared to hypothermia only, the DXM hypothermia group required more saline, adrenaline and cardiac arrests (all p<0.05). These adverse events occurred at both high and low dose DXM.
Conclusion Adverse cardiovascular events with low and high dose DXM combined with cooling occurred mainly after 16 h and could be due to perturbed central autonomic function, vasoconstriction via peripheral alpha adrenoceptor stimulation or effects on the imidazoline receptor.