Sepsis-related adrenal dysfunction in HIV-positive and negative critically ill patients using a 1 μg short synacthen test

Introduction

Sepsis is a common problem in our ICU, often leading to hypotension requiring vasopressor support. Adrenal dysfunction is thought to be common in septic patients. HIV-related opportunistic infections are known to be the most common cause of adrenal dysfunction. The prevalence of HIV in the community we service is around 20%. We will present here the preliminary results from a study on septic patients admitted to our ICU. We have assessed HIV status and CD4 counts on consecutive ICU admissions over a 4-month period. All patients requiring vasopressors have undergone a synacthen test.

Method

A prospective, observational, experimental study at an academic ICU. A presenting sample was taken over a 4-month period. Ethics approval was obtained from the University Ethics Committee.

Testing

A 1 μg low-dose short synacthen test (SST). Baseline bloods for renin, aldosterone, HIV and CD4. The laboratory was blinded to patient details and the physician blinded to results. One hundred and twenty-six patients enrolled and 40 synacthen tests were carried out. Results were available for 68 patients and 20 synacthen tests as of 14 December 2004. No renin, aldosterone and CD4 counts were available at submission of abstract.

Results

Sixty-eight patients admitted to the ICU were enrolled and followed up to D28 in 6 weeks. Twenty SSTs were performed for refractory hypotension within 24 hours of initiating vasopressors. The incidence of adrenal dysfunction (AD) was highest with a stress cortisol (SC) < 690 nmol/l or a delta cortisol (D30/60) < 250 nmol/l (89% in either case). Primary AD was more common then secondary AD and tertiary AD combined (89% vs 11%). A SC < 690 or a (D30/60) < 250 during a SST were more sensitive than a SC of < 550 nmol/l in detecting AD (89% vs 74%). Hemodynamic response (HR) is defined as an increase in MAP or decrease in vasopressor requirements in the 24 hours post steroid initiation. At a threshold of 10%, 68% responded to steroid treatment. The median increase in MAP or vasopressor decrease during the 24 hours post steroid initiation was 28%. There was no significant difference in mortality between steroid-treated AD and patients without AD (P = 0.91). Of the 68 patients, 17 were HIV-positive and 51 were HIV-negative. The period prevalence (1.5 months) is 25%. There was no significant difference in mortality between HIV-negative and HIV-positive (without AIDS-defining illnesses) patients (P = 0.29).

Conclusion

There is a high incidence of AD in septic shock. The most sensitive means of detection is a SC < 690 nmol/l or a D30/60 < 250 nmol/l. Primary AD is much more common than secondary AD. The increased mortality and haemodynamic instability of AD is eliminated by steroid treatment. Finally, HIV status alone does not impact on mortality in disease unrelated to HIV/AIDS. On completion we will be able to comment on the diagnostic performance of renin and aldosterone and their relationship to AD and ARF and the CD4 count, and its ability to predict mortality in HIV-positive patients.