HORMONE RESPONSES TO STRESS IN PATIENTS WITH MAJOR BURNS

The responses of the plasma stress hormones corticotrophin (ACTH), vas opressin (AVP), cortisol and corticotrophin releasing hormone (CRH) ha ve been studied in seven consecutive patients aged between 15 and 65 y ears who suffered from burns of 15-95% total body surface area. There was a distinct peak in AVP (up to 100 pmol/l) and ACTH levels well abo ve the upper limit of normal in all except one patient within 24 h of burn injury. Following the initial rise, AVP and ACTH tended to fall. Plasma CRH with one exception remained within the normal range. Concur rent measurement of plasma renin activity (PRA), haemoglobin (Hb), hae matocrit (Hct) and plasma sodium (Na), to assess hydration, showed tha t PRA was increased in all except one patient during the first 4 days of hospital admission. The correlation between ACTH and cortisol was h ighly significant (P<0.001), as was the correlation between ACTH and A VP, AVP and Na, PRA and Hb, and Hct and Na. Other significant correlat ions were ACTH and Hct (P=0.023), ACTH and Na (P=0.017), AVP and Hct ( P=0.029), CRH (P=0.018), CRH and Hb (P=0.001). No significant correlat ion could be demonstrated between CRH and ACTH or AVP. Our findings su ggest that AVP plays a role in the hypercortisolaemia which accompanie s major burns. The possible detrimental effect of very high levels of AVP leading to progression of burn depth and reduction of skin graft t ake by its potent vasoconstrictive action and water retention effect ( resulting in oedema) deserves further study. As AVP has the potential to reduce tissue perfusion, the possible use of antagonists in major b urns merits further consideration. Persistently raised PRA levels, des pite normal biochemical and haematological parameters, may indicate th at volume expansion therapy may not be adequate, and that both hypovol aemia and stress may contribute to the AVP response. Stress hormone mo nitoring may lead to better treatment and a reduction burn stress.