Evaluation and Treatment of Essential Hypertension During Short Duration Space Flight

During the last four decades of manned space flight, two individuals have successfully flown in space with the preflight diagnosis of essential hypertension (HTN). Treatment of this disease process in the astronaut population warrants special consideration particularly when selecting medication for a mission. A retrospective review of data offers two different clinical scenarios involving the treatment, or lack thereof, for essential hypertension during space flight. Case I; A Caucasian quinquagenerian diagnosed with HTN one year prior to the mission obtained flight certification after a negative diagnostic workup. The patient was placed on a diuretic. Preflight isolated blood pressure (BP) measurements averaged 138/102. Inflight, the patient electively declined medication. A 36-hour BP monitor revealed an average value of 124/87. Postflight, BP measurements returned to preflight BP values. Case II: A Caucasian quatrogenerian diagnosed with HTN 6 months prior to launch completed flight training after a negative diagnostic workup. The patient was placed on an ACE inhibiter. Preflight BP measurements averaged 130/80. Inflight, isolated BP measurements were considerably less. Normotensive values were obtained postflight. In both cases, BP values inflight were lower than pre or postflight values. Yelle et al has confirmed similar findings in the normotensive astronaut population. Spaceflight may result in fluid shifting, mild dehydration, electrolyte imbalance, orthostatic hypotension, and increased heart rates. Based on these factors, certain classes of antihypertensive agents such as vasodilators, beta-blockers, and diuretics are excluded from consideration as a primary therapeutic modality. To date, Ace Inhibitors are viewed as the more acceptable drug of choice during spaceflight. Newer classes of drugs may also provide additional choices. Presently, astronauts developing uncomplicated HTN may continue their careers when treated with the appropriate class of continue their careers when treated with the appropriate class of antihypertensive medication.