SOAP II – That’s cleaned that up then.

Dopamine has been the vasopressor of choice in septic patients in continental europe historically, although this may be changing. Dopamine has theoretically beneficial effects in maintaining splancnic and renal perfusion although in the SOAP trial (observational) suggested that there was an excess of mortality of dopamine treated patients. The old story of “renal dose dopamine” having an additional effect over and above the improvement in perfusing pressure has been discredited, but this result suggests a harmful signal over and above noradrenaline (the preferred agent in the UK).

Comparison of dopamine and norepinephrine in the treatment of shock. De Backer DN, et al. N Engl J Med. 2010 Mar 4;362(9):779-89.

The SOAP II trial was an RCT designed to answer this question. 8 centres in Austria, Spain and Belgium recruited 1679 patients to 2 groups based on reasonable shock inclusion criteria. Interestingly there was no attempt to limit inclusion to pure vasodilatory shock, 16% of patients were thought to have cardiogenic shock at recruitment. Intervention was dopamine or noradrenaline to 20ug/kg/min or 0.19ug/kg/min respectively, at which point additional inotropic / vasopressor was allowed (cross over). Of note requirement for ‘adequacy’ of fluid resuscitation were minimal (500 -1000mls clear fluids in, no goal directed therapy), thus patients may well have been under filled when the intervention began.

Randomisation & blinding appeared robust. The study was powered to have an 80% chance of detecting a 15 % mortality difference at 28 days, a difference I think is substantial. Although this may have been the result from the SOAP trial, I think it unlikely that the intervention planned would lead to this differentiaion (allowing as it did open label NA at relatively minimal infusion rates). The patients were well matched at baseline, and drop out rates and follow good.

Achieved MAPs were minimally higher in the NA group, and quantities of open label NA was significantly higher in the dopamine group (suggesting that NA is more effective at achieving MAP targets at given infusion rates). Other CVS & Renal surrogates were similar.

Primary end point was 28 day mortality; no significant difference (52 vs 48% OR 1.17 (0.97-1.42)). Interestingly a higher mortality than expected, despite a 20% rate of APC use within the trial. This may offset concerns as to the validity of the power calculation. Arrhythmia (AF commonly) was significantly more common in the dopamine group, and in the predetermined cardiogenic shock group mortality was significantly higher (p=0.03 although not powered for this outcome, and I suspect inadequately defined subgroup).

Should the result of this trial alter our practise ? No….we use NA for vasopressor therapy in the UK. The trial may well lead to practise changing on the continent, and thus the removal of one more confounding factor in future trials, increasing applicability. Despite the American College of Cardiology recommendation that dopamine is first line inotropic support in acute MI, outside perioperative cardiac bypass use (guided by TOE) I think there is currently no indication for dopamine therapy in AICU (but for dobutamine and dopexamine watch this space !). Anyone disagree ?

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