Adipose tissue lipolysis and circulating lipids in acute and subacute critical illness: Effects of shock and treatment

Purpose: The purpose of this study is to assess lipid metabolism at the tissue level in critically ill subjects. Materials and methods: We studied 182 patients with systemic inflammatory response syndrome/severe sepsis or shock during the acute (day 1) and subacute phase of critical illness (day 6). All subjects had a tissue microdialysis (MD) catheter placed in femoral adipose tissue upon admission to the intensive care unit (ICU). Plasma cholesterol, high-density lipoprotein, low-density lipoprotein, free fatty acids (FFAs), triglyceride, and MD glycerol (GLYC) were measured on days 1 and 6 in the ICU. Results: On admission, 56% of the patients had increased levels (> 200 μmol/L) of MD GLYC. Patients with shock displayed more pronounced subcutaneous tissue lipolysis and more profound derangements of circulating lipids vs patients without shock (but no appreciable differences in FFA levels). Furthermore, in patients with shock during the acute period, there were positive, albeit weak, correlations of subcutaneous tissue lipolysis (MD GLYC), plasma FFAs (r = 0.260; P = .01), and norepinephrine's dose (r = 0.230; P = .01), whereas during the subacute phase, MD GLY levels were higher in patients receiving glucocorticoids (344.7 ± 276.0 μmol/L vs 252.2 ± 158.4 μmol/L; P = .03). Conclusions: Subcutaneous tissue lipolysis is only one of the many determinants of plasma FFAs. Routinely applied therapeutic modalities in the ICU interfere with adipose tissue metabolism.