Use of vasopressor agents in critically ill patients.

Distributive shock is a common problem in intensive care. Systemic hypotension is a medical emergency and will cause end-organ injury if not reversed. There are relatively few medications available to treat distributive shock. Catecholamines are most widely used for this indication and work by stimulating alpha- and/or beta-adrenergic receptors. Vasopressin and corticosteroids may have a role in reversing refractory shock and work primary through nonadrenergic mechanisms. Shock is difficult to define using hemodynamic criteria, because the same hemodynamic values can be normal in one patient, yet represent shock in another. Thus, the appropriate therapeutic endpoints for vasopressor therapy are not uniform for all patients. Similarly, the available evidence comparing vasopressor agents in terms of safety and efficacy is limited. When used at doses necessary to reverse distributive shock, less potent vasoconstrictors (eg, dopamine) do not appear to be safer than more potent ones (eg, norepinephrine) and do not appear to be as effective.