Delivery dependent oxygen consumption in patients with septic shock: daily variations, relationship with outcome and the sick-euthyroid syndrome.

Delivery dependent oxygen consumption (DDOC) is observed in patients with sepsis and vital organ dysfunction, and has been related to outcome. Similarly the sick-euthyroid syndrome is associated with a high mortality. We examined the daily variations of DDOC and its relation to hormonal changes, particularly those of the thyroid. In 22 patients, 14 with septic shock and 8 post-operative controls, oxygen delivery was increased by increasing cardiac output with vasodilation by phentolamine, during a total of 207 days. DDOC varied markedly between consecutive days in individual patients with sepsis, in both survivors and non-survivors. DDOC was related to severity of illness, assessed by APACHE II score (r = 0.50, p = 0.017), and plasma levels of triiodothyronine (T3), r = -0.49, p = 0.011, and thyroxine (T4), r = -0.53, p = 0.012. No correlation was observed between DDOC and outcome, nor blood levels of lactate, epinephrine, norepinephrine, dopamine or cortisol. In conclusion, we observed a marked disturbance of systemic oxygen uptake autoregulation in patients with septic shock which varied during the clinical course and was related to the sick-euthyroid syndrome.