title: Efficacy of Doppler ultrasound [correction of utrasound] for screening symptoms of decompression sickness during simulated extravehicular activities.
abstract: Doppler ultrasound is frequently used for monitoring  circulating microbubbles during decompression to assess the symptoms of Decompression Sickness (DCS). This analysis was carried out to evaluate its effectiveness for screening symptoms of DCS during simulated extravehicular activities (EVA). The information from various hypobaric chamber studies carried out at the NASA Johnson Space Center, Houston, TX was used in this analysis (n=516). The circulating microbubbles were detected in the precordial area in 42% (218/516), and symptoms were reported in 16% (81/516) of these exposures. The accuracy of Doppler-detectable bubbles (Spencer grades) on all symptoms of DCS was examined by calculating measures of sensitivity and specificity. The efficacy of Doppler as a screening device was examined by calculating their positive predictive value (PPV) and negative predictive value (NPV). The results of these analyses indicated that the sensitivity of Doppler decreased, and the PPV increased with higher Spencer grades.  However, the likelihood of detecting true negative cases (NPV) was consistently higher with all bubble grades. Due to the high false-positive rate and low prior probabilities of the risk of DCS, Doppler was found to be more useful to identify those who did not develop DCS, than to detect positive cases of DCS in the simulated EVA exposures.
authors.affiliation: KRUG Life Sciences, Houston, TX 77058, USA.
authors.forename: K V
authors.initials: KV
authors.lastname: Kumar
authors.forename: J M
authors.initials: JM
authors.lastname: Waligora
mesh_terms: D003665:Decompression Sickness / Q000175:diagnosis*; D005069:Evaluation Studies as Topic; D018478:Extravehicular Activity; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018561:Space Simulation; D018608:Ultrasonography, Doppler