Free Fatty Acids and Delayed Cerebral Ischemia After Subarachnoid Hemorrhage

Abstract

Background and Purpose— The purpose of this study was to understand factors related to increases in serum free fatty acid (FFA) levels and association with delayed cerebral ischemia (DCI) after subarachnoid hemorrhage. Methods— We performed serial measurement of systemic oxygen consumption by indirect calorimetry and FFA levels by liquid chromatography/mass spectrometry in the first 14 days after ictus in 50 consecutive patients with subarachnoid hemorrhage. Multivariable generalized estimating equation models identified associations with FFA levels in the first 14 days after SAH and Cox proportional hazards model used to identified associations with time to DCI. Results— There were 187 measurements in 50 patients with subarachnoid hemorrhage (mean age, 56±14 years old; 66% women) with a median Hunt–Hess score of 3. Adjusting for Hunt–Hess grade and daily caloric intake, n-6 and n-3 FFA levels were both associated with oxygen consumption and the modified Fisher score. Fourteen (28%) patients developed DCI on median postbleed Day 7. The modified Fisher score ( P =0.01), mean n-6:n-3 FFA ratio ( P =0.02), and mean oxygen consumption level ( P =0.04) were higher in patients who developed DCI. In a Cox proportional hazards model, the mean n-6:n-3 FFA ratio ( P <0.001), younger age ( P =0.05), and modified Fisher scale ( P =0.004) were associated with time to DCI. Conclusions— Injury severity and oxygen consumption hypermetabolism are associated with higher n-FFA levels and an increased n-6:n-3 FFA ratio is associated with DCI. This may indicate a role for interventions that modulate both oxygen consumption and FFA levels to reduce the occurrence of DCI.