Abstract
BackgroundArginine is an amino acid determinant in the metabolic, immune and reparative responses to severe trauma. The present study aims to determine argininemia and plasma arginine bioavailability (PAB) in critical trauma patients and to analyze its correlation with prognosis.MethodsA prospective study of 23 critical trauma patients was undertaken. Aminoacidemias were determined, by ion exchange chromatography, at admission and in the first and third days and compared with those of 11 healthy individuals. PAB was calculated. Severity indexes and outcome parameters were recorded.ResultsValues of argininemia, citrullinemia and ornithinemia at the admission were significantly lower than those of the controls (arginine: 41.2 ± 20.6 versus 56.1 ± 11.9 μmol/L, P = 0.034). Hipoargininemia (<60 μmol/L) prevalence was 82.6 %. Mean PAB was 62.4 ± 25.6 %. Argininemia < 26 μmol/L constituted a significant predictive factor of in-hospital mortality [n = 4 (17.4 %); 75 versus 15.8 %, P = 0.04; odds ratio = 4.7; accuracy = 87 %] and lower actuarial survival (63.5 ± 43.9 versus 256.1 ± 33.3 days, P = 0.031). PAB <42 % [n = 6 (26.1 %)] was associated with higher lactacidemia levels (P = 0.033), higher in-hospital mortality (66.7 versus 11.8 %, P = 0.021; odds ratio = 5.7, accuracy = 82.6 %) and lower actuarial survival (87.2 ± 37.5 versus 261.4 ± 34.7 days, n.s.). Probability of in-hospital mortality was inversely and significantly related with PAB [61.8 ± 8.8 % (95 % CI 50.8–72.7) when PAB <41 % and 2.8 ± 1.9 % (95 % CI 1.9–8.3) when PAB > 81 %, P = 0.0001]. Charlson’s index ≥1, APACHE II ≥19.5, SOFA ≥7.5, and glutaminemia < 320 μmol/L were also predictive factors of actuarial survival.ConclusionsThose results confirm the high prevalence of arginine depletion in severe trauma patients and the relevance of argininemia and PAB as predictive factors of mortality in this context.
Highlights
Arginine is an amino acid determinant in the metabolic, immune and reparative responses to severe trauma
Charlson’s index ≥1, APACHE Simplified Acute Physiology Score II (II) ≥19.5, Sequential Organ Failure Assessment (SOFA) ≥7.5, and glutaminemia < 320 μmol/L were predictive factors of actuarial survival. Those results confirm the high prevalence of arginine depletion in severe trauma patients and the relevance of argininemia and plasma arginine bioavailability (PAB) as predictive factors of mortality in this context
Arginine is a conditionally essential amino acid involved in protein synthesis; ureagenesis and ammonia detoxification; nitric oxide metabolism; production of proline, polyamines, creatine and agmatin; and hormonal secretion [1,2,3,4]
Summary
Arginine is an amino acid determinant in the metabolic, immune and reparative responses to severe trauma. Arginine is a conditionally essential amino acid involved in protein synthesis; ureagenesis and ammonia detoxification; nitric oxide metabolism; production of proline (used for collagen synthesis and tissue repair), polyamines (primary regulators of cellular growth and proliferation), creatine and agmatin; and hormonal secretion (including growth hormone, insulin and prolactin) [1,2,3,4]. Three isoforms of NOS are relevant: NOS 1 (neuronal) and NOS 3 (endothelial) that are constitutive enzymes; and NOS 2 (inducible) that is markedly induced during inflammation Both arginase I and inducible NOS (iNOS) are inducible enzymes in myeloid cells, with arginase I being induced by T-helper 2 (Th2) cytokines and iNOS by T-helper 1 (Th1) cytokines [4,5,6]. Preponderant type of reaction is influenced by the nature of injury [7], namely Th2 response in trauma and major surgery and Th1 response in sepsis
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