Fat embolism after lipid emulsion infusion

Nitric oxide involvement in lipid emulsion-induced vascular pain in anesthetized rats

We examined the vascular pain induced by arterial infusion of 20% lipid emulsion by using a flexor reflex model in anesthetized rats. Arterial infusion of 20% lipid emulsion at doses of 0.6 to 2 ml/2 min induced flexor reflexes that were late in onset, persistent, and intense compared with those induced by 2.7% amino acid and 7.5% glucose solution, 5% sodium chloride solution, 1% propofol, and capsaicin. The flexor reflex induced by 20% lipid emulsion was significantly inhibited by preinjected procaine hydrochloride (4 mg/rat, i.a.) but not by the critical dose of indomethacin (10 mg/kg, i.p.). These results suggest that the flexor reflex might reflect a 20% lipid emulsion-induced vascular pain response and that the site of action of noxious agents involved in this event might be a vascular bed, but the production of prostanoids through cyclooxygenase might not be involved in the action mechanisms. The 20% lipid emulsion-induced vascular pain was significantly inhibited by preinjection of 10 mg/kg N(G)-nitro-l-arginine methyl ester hydrochloride (l-NAME), a nitric oxide (NO) synthase inhibitor, and the inhibition by l-NAME was recovered by the addition of sodium nitroprusside (30 microg/kg/min), which is an endothelium-independent NO donor to 20% lipid emulsion. These results indicate that increased NO production is responsible for 20% lipid emulsion-induced vascular pain. In summary, the arterial infusion of 20% lipid emulsion induced a delayed, persistent and intense flexor reflex, presumably indicating vascular pain in rats that might be induced by NO production through the activation of NO synthase.

[Intra-macrophage lipid particles collected by bronchoalveolar lavage: incidence and diagnostic value]

This study aimed to determine the incidence and diagnostic value of fat-laden alveolar macrophages obtained by bronchoalveolar lavage (BAL). In 128 patients, including 66 patients admitted for multiple trauma, 158 BAL were carried out. However, 41 BAL from 32 patients were excluded because of poor quality of samples (not enough macrophages, too many ciliated cells, or haemorrhage). All the patients were intubated and mechanically ventilated, having pulmonary infiltrates on the chest film. BAL samples were examined after staining with oil-red-O. They were considered to be positive when more than 5% of alveolar macrophages contained fat droplets. Among them 14 out of 47 patients (30%) without multiple trauma were positive; 7/14 had never been given any intravenous lipid infusion, and 5/14 had aspiration pneumonia (as opposed to 3/32 patients with negative BAL). Further 27 patients out of the 49 (55%) with multiple trauma were positive. Among them 10/49 had clinical evidence of fat embolism, however, only 7/10 had positive samples. All these last ten patients had been given intravenous lipid infusions. The rate of positive alveolar macrophages was correlated neither with the plasma triglyceride concentration, nor the Fracture Index Score, nor the delay between the end of the lipid infusion and the BAL. There was no significant difference in PaO2/FIO2 ratio between the patients with positive and negative BAL. Positive BAL was significantly associated with lipid infusions. The data therefore suggest that the presence of fat-laden alveolar macrophages are associated with various pathological pulmonary conditions, particularly aspiration pneumonia and lipid infusions.(ABSTRACT TRUNCATED AT 250 WORDS)