What should be administered if hypotension is unresponsive to isotonic fluids and IM epinephrine during anaphylaxis treatment?

In cases of anaphylaxis where hypotension persists despite the administration of isotonic fluids and intramuscular epinephrine, the appropriate next step is to initiate a vasopressor infusion. This decision is based on the understanding that anaphylaxis can lead to severe vasodilation and decreased vascular resistance, contributing to profound hypotension. While epinephrine is a critical first-line treatment for anaphylaxis, sometimes, additional support is required to stabilize blood pressure and maintain perfusion to vital organs.

Vasopressors, such as norepinephrine or phenylephrine, can help counteract vasodilation by increasing systemic vascular resistance and improving blood pressure when isotonic fluids and epinephrine are insufficient. These medications work by stimulating adrenergic receptors, which leads to vasoconstriction and increased cardiac output.

Other interventions, such as oxygen therapy, are essential for managing respiratory distress but do not directly address the hypotension caused by anaphylaxis. Similarly, while further fluid boluses may be considered in some cases, if there is no response to initial fluid therapy and epinephrine, relying on additional fluids may not effectively resolve the hypotensive crisis. Therefore, initiating a vasopressor infusion is the most appropriate course of action in