Thursday, May 11, 2006

Astronaut, Diver?



In the April 2006 Journal, Aviation, Space and Environmental Medicine there is an article exploring the possible benefit of performing cardiac screening studies on prospective astronauts in an effort to prevent the possible catastrophe of a coronary event while on board the space station. Due to the limited treatment and return capabilities of most space vehicles, an in-flight cardiac event could result in significant mission impact or even failure. The current literature supports including electron-beam computed tomography (EBCT) and highly selective C-reactive protein (hsCRP) for diagnosis of coronary artery disease (CAD) in asymptomatic, low-pretest probability cohorts.

Divers Alert Network has reported for several years now the high risk of death from an untoward coronary event while diving. Since the diver is in an alien environment and basically is an astronaut for that brief period that s/he is underwater, it seemed apropos to me that a similar screening could be done for divers - given the cost could be made reasonable. As a screening tool for divers, the EBCT would probably be out of the question - but a highly selective CRP [hsCRP] when correlated with other known risk factors would be inexpensive and would serve to keep divers out of the water while further diagnosis and treatment was done.
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Aviat Space Environ Med. 2006 Apr;77(4):377-87.

Cardiac health for astronauts: coronary calcification scores and CRP as criteria for selection and retention.

Hamilton DR, Murray JD, Ball CG.

Wyle Laboratories, Houston, TX 77058, USA. dhamilton@wylehou.com

Due to the limited treatment and return capabilities of most space vehicles, an in-flight cardiac event could result in significant mission impact or even failure. The current literature supports including electron-beam computed tomography (EBCT) and highly selective C-reactive protein (hsCRP) for diagnosis of coronary artery disease (CAD) in asymptomatic, low-pretest probability cohorts. This paper will examine the issues surrounding adding these tests to astronaut retention and selection algorithms. An evidenced-based literature review was performed and consensus obtained from subject-matter experts to create novel cardiac screening algorithms for astronaut applicants and the current astronaut corps. The main focus of this paper is to derive an evidenced-based approach for improving the diagnosis of significant CAD using EBCT and hsCRP testing. The recommended initial astronaut selection and long-duration mission assignment screening algorithms use EBCT-derived calcium scores and serum hsCRP levels to screen for CAD and predict individual cardiac risk. The current medical evidence is compelling for the international space medicine community to consider: (1) Astronaut candidates with a coronary artery calcium score >0 should be disqualified from initial selection; (2) Astronauts with a coronary artery calcium score >100 should be disqualified from selection for long-duration missions; (3) Elevated hsCRP is a reliable risk factor for helping predict future cardiac events that should warrant primary prevention but not necessarily medical disqualification.

Further Reading:
Coronary Artery Disease