Identical vials with hydrocortisone or placebo will be prepared in an industrial pharmacy and labeled using alphabetic letters (A, B, C, D) before the beginning of the study. Each vial of hydrocortisone will have 100 mg of hydrocortisone ponder to be diluted in 10 ml of normal saline 0.9% Each vial of placebo will content a innocuous ponder, also to be diluted in 10 ml of normal saline 0.9%. The drug and its referent letter (A, B, C, D) will be controlled by two lists, handed in by the pharmacist to the researchers inside closed envelopes before the beginning of the study. After enrollment and randomization, children joining the study will have baseline cortisol and ACTH measured. ACTH testes (1 mcg/ 1.75m2 and 250 mcg) will be performed, 4 hours apart. After this, patients will receive the study drug (either hydrocortisone or placebo), 0.2 ml/kg/ dose, 8 hourly. This will last the period the patient requires vasoactive support, or a maximum of 7 days. Daily routine blood results will be noted, as well as a further ACTH test on day 3 if the patient is still on vasoactive support. Demographic data will be collected on enrollment.