Effects of intravenous fat emulsions on lung function in patients with acute respiratory distress syndrome or sepsis
ABSTRACT To investigate whether rapid or slowly infused intravenous fat emulsions affect the ratio of prostaglandin I2/thromboxane A2 in arterial blood, pulmonary hemodynamics, and gas exchange.
Prospective, controlled, randomized, crossover study.
Operative intensive care unit of a university hospital.
Eighteen critically ill patients. Ten patients were stratified with severe sepsis, and eight patients had acute respiratory distress syndrome (ARDS).
Patients were assigned randomly to receive intravenous fat emulsions (0.4 x resting energy expenditure) over 6 hrs (rapid fat infusion) or 24 hrs (slow fat infusion) along with a routine parenteral nutrition regimen, by using a crossover study design.
Systemic and pulmonary hemodynamics as well as gas exchange measurements were recorded via respective indwelling catheters. Arterial thromboxane B2 and 6-keto-prostaglandin-F1alpha plasma concentrations were obtained by radioimmunoassay, and 6-keto-prostaglandin-F1alpha/thromboxane B2 ratios (P/T ratios) were calculated. Data were collected immediately before and 6, 12, 18, and 24 hrs after onset of fat infusion. In the ARDS group, P/T ratio increased by rapid fat infusion. Concomitantly, pulmonary shunt fraction, alveolar-arterial oxygen tension difference [P(a-a)o2]/Pao2, and cardiac index increased as well, whereas pulmonary vascular resistance and Pao2/Fio2 declined. After slow fat infusion, a decreased P/T ratio was revealed. This was accompanied by decreased pulmonary shunt fraction, lowered P(a-a)o2/Pao2, and increased Pao2/Fio2. Correlations between plasma concentrations of 6-keto-prostaglandin-F1alpha or thromboxane B2 and measures of respiratory performance could be shown during rapid and slow fat infusion, respectively. In the sepsis group, the P/T ratio remained unchanged at either infusion rate, but pulmonary shunt fraction and P(a-a)o2/Pao2 decreased after rapid fat infusion, whereas Pao2/Fio2 increased.
Pulmonary hemodynamics and gas exchange are related to changes of arterial prostanoid levels in ARDS patients, depending on the rate of fat infusion. In ARDS but not in sepsis patients clear of pulmonary organ failure, a changing balance of prostaglandin I2 and thromboxane A2 may modulate gas exchange, presumably via interference with hypoxic pulmonary vasoconstriction.
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ABSTRACT: Objective. The aim of the study was to determine whether lipopolysaccharide (LPS)- induced cytokine release by human alveolar cells is modified by addition of omega (n)-3 and n-6 polyunsaturated fatty acids (PUFAs). Materials and methods: After LPS challenge, PUFAs were added to A549 cells as docosa- hexaenoic acid (DHA, n-3) plus arachidonic acid (AA, n-6) in four different n-3/n-6 ratios (1:1, 1:2, 1:4, and 1:7), then tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-8, and IL-10 con- centrations were measured. Results: The release of proinflammatory cytokines (TNF-α, IL-6, and IL-8) was reduced by 1:1 and 1:2 n-3/n-6 PUFA ratios (p < 0.05 to p < 0.001), but increased by 1:4 and 1:7 n-3/n-6 ratios (p < 0.05 to p < 0.001). The 1:1 and 1:2 n-3/n-6 ratios induced the release of the antiinflammatory cy- tokine IL-10 (p < 0.001). The 1:1 ratio had the greatest effect on cytokine release (p < 0.001). Conclusion: Our results confirm that n-3 PUFAs are able to modify the balance between proin- flammatory and antiinflammatory forces also via modulation of cytokine release. (Nutritional Therapy & Metabolism 2008; 26: 36-44)
Article: (Teil)parenterale Ernährung[Show abstract] [Hide abstract]
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