Systemic steroids for severe sepsis and septic shock (Review)
The benefits of corticosteroids as a treatment for severe sepsis and septic shock (if any) are unknown:
Although adrenal suppression is common in sepsis, it is still unclear how to assess adrenal function, or whether it should be done at all. The sensitivity and specificity of the cosyntropin (ACTH) stimulation test are unknown, and its utility uncertain. There is no good evidence base even to define what adrenal suppression is (in terms of lab cut-off values) in people with severe sepsis. Nevertheless, the Society of Critical Care Medicine continues to recommend we call it "corticosteroid insufficiency" and define it in the old way (a cortisol increase of <9 mcg/dL after a 250 mcg ACTH stimulation test, or a random cortisol < 10), without advising it be routinely checked.
Annane's practice-changing study published in 2002 showed that among 300 septic shock patients, those with a negative cosyntropin stimulation test ("non-responders") randomized to 50 mg hydrocortisone IV q 6 hours had significantly improved 28-day mortality compared to placebo (53% vs. 68%). The trial was criticized for changing enrollment criteria mid-study and use of adrenal-suppressing etomidate for intubation on most patients, leading to a 72% rate of adrenal suppression/non-responders.
CORTICUS then swung the pendulum back by showing no 28-day mortality benefit of steroids in 499 septic shock patients (39% vs. 36%) who were non-responders to cosyntropin. Steroids did reduce the time spent in shock (3.3 vs. 5.8 days), but steroid-treated patients had more superinfections and new episodes of sepsis. CORTICUS was likewise criticized for changing enrollment criteria mid-study, not meeting its enrollment targets, and its low mortality rate compared to prior studies.
Summing up, corticosteroids do improve blood pressure, but any beneficial effects on survival from septic shock remain hotly debated.

Clinical Takeaway: The Surviving Sepsis Guidelines are unchanged from 2008, and continue to recommend:
Hydrocortisone 300 mg / day or less in patients with septic shock "only after it has been confirmed that their blood pressure is poorly responsive to fluid resuscitation and vasopressor therapy." (Grade 2C: weak recommendation, low quality evidence). What does "poorly responsive" to vasopressor therapy mean? Dear Reader, that's always been up to you to decide.
No benefit of continuous vs. bolus infusions has been demonstrated (continuous produces less hyperglycemia, but more of a rebound effect after discontinuation).
Adding fludrocortisone to hydrocortisone is not supported by the COIITS trial, in which it was associated with a higher infection rate, and shouldn't be necessary as hydrocortisone has mineralocorticoid activity. Surviving Sepsis calls fludrocortisone an optional adjunctive treatment to hydrocortisone.
Give hydrocortisone for 7 days, then wean it to prevent rebound hypotension and blood glucose lability.
Stick with the 300 mg / day dose: giving high-dose corticosteroids to people in septic shock is known to be harmful.
Systemic Steroids in Severe Sepsis and Septic Shock. AJRCCM 2012;185:133-139.