Dietary fat composition alters pulmonary function in pigs.
OBJECTIVE
We investigated the effect of various dietary fats on pulmonary surfactant composition and lung function changes that occur before and after endotoxin infusion in pigs.


METHODS
Eighteen pigs were assigned to three groups (n = 6 per group) to receive a diet of protein (20% of calories), carbohydrate (20% of calories), and fat (40% of calories). In one group the fat content consisted entirely of palmitic acid. In the second group, fat came from Intralipid, which provided predominantly linoleic acid. The third group was fed fish oil. Pigs were maintained on these diets for 21 d before the experiment. Cardiovascular and pulmonary functions were determined on day 22. Pigs then were infused with endotoxin (80 mg. kg(-1). min(-1)) until the pulmonary arterial pressure reached a pressure similar to that found in trauma victims (45 to 50 mmHg). Cardiovascular and pulmonary function tests were then repeated, the animals killed, and the lungs removed for study.


RESULTS
Compliance was reduced in the linoleate and fish-oil groups compared with the palmitate group before and after endotoxin. Compliance changes in pigs fed the linoleate and fish-oil diets were consistent with significant increases in lung wet:dry weight ratios, increased CO(2) retention, histologic evidence of vascular congestion, intra-alveolar edema, and alveolar septa thickening. Changes in surfactant phosphatidylcholine composition between groups were consistent with the notion that increased unsaturated fatty acids could affect surfactant function.


CONCLUSIONS
We concluded that the common practice of providing calories in the form of polyunsaturated fatty acids to critically ill patients carries the risk of being detrimental to lung function.
Wolfe
Robert R
RR
Department of Surgery, The University of Texas Medical Branch, Galveston, Texas, USA. rwolfe@utmb.edu
Martini
Wenjun Z
WZ
Irtun
Oivind
O
Hawkins
Hal K
HK
Barrow
Robert E
RE
D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage; D004731:Endotoxins / Q000008:administration & dosage; D002149:Energy Intake; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage; D005395:Fish Oils / Q000008:administration & dosage; D007958:Leukocyte Count; D019787:Linoleic Acid / Q000008:administration & dosage; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance; D009504:Neutrophils; D019308:Palmitic Acid / Q000008:administration & dosage; D010713:Phosphatidylcholines / Q000032:analysis; D011654:Pulmonary Edema / Q000209:etiology; D011663:Pulmonary Surfactants / Q000032:analysis*; D013552:Swine
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D004731:Endotoxins; D005217:Fat Emulsions, Intravenous; D005395:Fish Oils; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D019308:Palmitic Acid; D019787:Linoleic Acid