Is serum lactic acid a reliable indicator for diagnosing fat embolism syndrome?

Introduction: The incidence of Fat Embolism Syndrome (FES) has been reported to occur in 0.5 to 3% of patients with isolated long bone fracture. FES is most commonly associated with long bone fractures, if associated with polytrauma then the chance of manifestation increases by 11%. Fat embolism is a clinical entity diagnosed mainly by Gurd’s criteria which includes clinical signs and blood parameters. There is no single blood parameter to detect FES at earliest. A high lactate level is an early sign of tissue hypoxia. In patients with femur shaft fracture tissue hypoxia is the most important cause of increased lactate levels. Increased blood lactate level is related to increased mortality. Aim: To establish the relationship between serum lactic acid and fat embolism in patients with fracture shaft of the femur. Materials and Methods: The present was a prospective study done at Kasturba Medical College Hospitals, Mangalore, Karnataka, India, on 40 patients with femur shaft fracture. Statistical analysis was done using SPSS (version 17.0). Results: In the present study, four patients out of 40 had FES (Gurd’s criteria), whose serum lactic acid was high (>25) within 72 hours of injury. Fourteen patients had elevated lactic acid (>20) but did not develop FES. All patients with FES had elevated serum lactic acid which was statistically significant (p-value 0.003), yet serum lactic acid estimation was less sensitive 28.7%. Conclusion: In conclusion serum lactic acid is specific (100%) for fat embolism but not sensitive (28.7%). By using serum lactic acid level, development of fat embolism can’t be predicted however, elevated lactic acid level will help us in risk stratification.