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22-08-2011 | Article

Adrenal gland volume linked to septic shock survival


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MedWire News: Computed tomography (CT) identification of adrenal gland volume may identify septic patients who could benefit from steroid therapy, suggest study findings.

"The use of low-dose steroids in patients with septic shock appears to improve mortality in subgroups of patients, but identification of patients who will benefit is difficult," say Samir Jaber (University of Montpellier, France) and co-authors.

For the study, the team performed a short cosyntropin test and determined adrenal volume by CT within 48 hours of shock in 184 patients with septic shock and in two control groups (40 ambulatory patients and 15 non-septic critically ill patients). The primary endpoint of the study was intensive care unit (ICU) mortality.

Patients in the septic shock group had significantly higher total adrenal gland volume compared with patients in the non-septic group, and with ambulatory patients, at 12.5 versus 8.0 and 7.2 cm3, respectively. No significant difference in adrenal volume was seen between the latter two groups.

Analysis of 100 patients with medical history before septic shock (on average 123 days) showed that during septic shock, adrenal gland volume increased significantly to 12.4 cm3 from a baseline value of 8.8 cm3.

Furthermore, among the 16 survivors who were explored with a CT scan adrenal gland volume returned to baseline on average 100 days after ICU discharge. No correlation was seen between adrenal gland volume measurement during septic shock and baseline cortisol concentration.

In septic shock, total adrenal gland volume during shock was significantly higher among the 125 survivors (13.8 cm3) compared with among non-survivors (9.7 cm3). Among the 100 patients who had a CT scan before and during septic shock, adrenal gland volume increased more during shock among survivors than non-survivors (33% vs 8%, respectively).

Receiver-operator characteristic curve analysis showed that a total adrenal gland volume of 10 cm3 as the best predictor of death with a sensitivity of 70%, specificity of 92%, a positive predictive value of 82%, and an accuracy of 84%.

Using this threshold, the likelihood ratio of death in the ICU was 8.7-fold greater if the total adrenal gland volume was less than 10 cm3. The best sensitivity and specificity (of 98%) was achieved using a cut-off 15 cm3 and 7.3 cm3, respectively.

The best cut-off value for baseline plasma cortisol concentration was 32 µg/dl with a sensitivity of 33 and a specificity of 79%. The team also found that 68% of patients with a change in cortisol levels less than 9 µg/dl and a total adrenal gland volume of less than 10 cm3 died before day 28, whereas only 14% of patients with a total adrenal gland volume higher than 10 cm3 and a change in cortisol level higher than 9 µg/dl died before day 28.

Total adrenal gland volume was strongly associated with 28-day survival (hazard ratio [HR]=5.0), with a volume above 10 cm3 an independent predictor of ICU survival (HR=0.014).

Writing in the journal Critical Care Medicine, Jaber and team conclude: "Further studies may evaluate the adrenal gland volume in association with the cosyntropin stimulation test in other populations at high risk of critical illness-related insufficiency such as brain-dead or multiple trauma patients, and whether assessment of adrenal gland morphology on CT may identify patients likely to respond to corticosteroids."

By Ingrid Grasmo