Utility of Doppler-detectable microbubbles in the diagnosis and treatment of decompression sickness

Doppler-detectable microbubbles (DMB) are frequently used to evaluate altitude decompression stress. However, the role of DMB in the therapy of decompression sickness (DCS) has not been examined.

The ability of Doppler to detect microbubbles during decompression (Doppler test) may be used in the diagnosis of DCS, and to aid clinical decisions about treatment options for DCS.

We examined the data on DMB and symptoms from NASA Database on DCS (n = 516). The accuracy of Doppler test was obtained from the Receiver Operating Characteristic (ROC) for DMB (grades I through IV), and efficacy was obtained by calculating predictive or post-test probabilities. Threshold analysis was used to obtain the probabilities for testing and/or treatment decisions.

The Doppler test was useful for both screening and confirming DCS, when different criteria (grade I for screening; grade IV for confirming) were used for a positive test. Calculation of predictive values and threshold analysis showed that: 1) early recompression was the therapy of choice when post-test probability of disease was > 0.25 in individuals with non-specific pain at altitude, and early recompression with 100% oxygen for 2 h at site level was optimal therapy when this probability was > 0.33; 2) hyperbaric therapy was optimal when post-test probability was > 0.04 in individuals with uncertain symptoms post-flight.

The Doppler test was of greater utility in excluding DCS than confirming its presence, and was useful in making therapeutic decisions on DCS when confronted with non-specific symptoms at altitude.