Friday, March 08, 2013

Helicopter Pilots: Associated Diseases and Sicknesses

Research studies have shown that pilots are more prone to numerous adverse health conditions related to chronic exposure to high altitudes (where there is less oxygen), and high speeds, temperatures, vibrations, and noise levels.

However, many of these studies lump airplane pilots together with helicopter pilots but the groups may be susceptible to different conditions due to different flight characteristics. For example, helicopter pilots do not fly as high and as fast as airplane pilots. Thus, studying helicopter pilots separately may be helpful.

In the current issue of Aviation, Space, and Environmental Medicine, researchers from China performed such a study to study the types of diseases helicopter pilots suffered as well as their sick leave time. The study involved a random sampling of 516 pilots between the ages of 20 and 52. Their medical records were reviewed to obtain medical diagnoses and sick leave time for each diagnosis.

Results of the study showed that the top three organ systems in helicopter pilots affected by disease are the digestive system, cardiovascular system, and the musculoskeletal system. The top three organ systems associated with the longest sick leave durations were the digestive system, musculoskeletal system, and the nervous system. Conditions in these organ systems accounted for 66% of sick leave time combined.

The three most common medical conditions for the helicopter pilots were fatty liver (9.88%), hyperlipidemia (high fat levels in the blood; 6.98%), and polypoid gallbladder lesions (3.42%). Fatty liver is a reversible condition where fat accumulates in the liver. Polypoid lesions of the gallbladder are types of polyps in the gallbladder. Polyps are a type of growth that projects from the lining of mucous membranes. A mucous membrane is one of four major types of thin sheets of tissue that line or cover various parts of the body. The gallbladder is a small, pear shaped sac, located under the liver, which helps store and transport bile to the first part of the small intestine. Bile is a bitter, yellow-green substance released from the liver that carries away waste products.

The three diseases associated with the longest sick leave periods in helicopter pilots were ground syncope (fainting; 7.23%, 157 sick days), chronic gastritis (inflammation of the stomach lining; 6.68%, 145 sick days), and lumbar (lower back) disc herniation (protrusion) (4.19%, 91 sick days). Lumbar disc herniation could have been related to chronic sitting in helicopter pilots. The authors suggested more efforts be made on controlling and preventing this problem in the future.

The study also showed that the helicopter pilots rarely suffered from specific aerospace related diseases/problems (e.g., hearing loss, loss of consciousness) that airplane pilots do, likely because of the differences in their flight characteristics.  However, the ground syncope was a significant concern which led the authors to suggest better training to tolerate high altitudes and speeds. It is not altogether if there is something specific about being a helicopter pilot that makes one prone to fatty liver, hyperlipidemia, and polypoid gallbladder lesions or if some other factor was the cause.        

Suggested reading: Pilot Medical Handbook: Human Factors for Successful Flying

Reference: Xiao, D., Li, H., Wang, X., Wang, B., Yan, Y. & Men, K. (2013). Prevalence of Disease Spectrum and Sick Leave Time Associated with Illness in Helicopter Pilots. Aviation, Space, and Environmental Medicine, 84, 3, 234-236.

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