Page 211 - PJ MED OPS Handbook 8th Ed

2) Treat specific traumatic injuries IAW PJ handbook or local protocols
3) Rest
b. Cardiovascular System
i) On earth: Gravity exerts a downward force, sets up a vertical hydrostatic gradient. When
standing, some ‘excess’ fluid resides in vessels/tissues of the legs
ii) In space: Loss of the hydrostatic gradient. Some fluid quickly redistributes toward the
chest and upper body. Sensed as ‘overload’ of circulating blood volume. The newly
sensed ‘excess blood volume’ is adjusted by reducing volume 12–15%. Red blood cells
are adjusted downward to maintain a normal concentration (relative anemia)
iii) Upon return to Earth: Gravity again pulls the fluid downward. Now there is a relative
2–3L deficit in both circulating fluid and red blood cells
iv) Signs/Symptoms:
1) Orthostatic intolerance
2) Decreased BP
3) Increased HR
4) Nystagmus and/or blurry vision
5) Weakness
6) Syncope
7) Confusion
8) Nausea
v) Time course: from landing up a few days
vi) Treatment:
1) Oral fluids if tolerating
2) 1L NS fluid bolus challenge, titrate as needed
3) Consider medications for nausea – caution for urinary retention and dose adjustment
4) Rest
5) Monitor vitals
6) With trauma, may need blood sooner than stage 3 shock
c. Neurosensory System
i) Inputs are immediately and radically altered in weightlessness because the gravitational
orientation is absent. Eventually there is adaptation to position sense and motion in
three dimensions without gravity. Upon returning to earth, the neurovestibular system
is still adapted to micro or zero gravity.
ii) Signs/Symptoms:
1) Vertigo
2) Unstable gait
3) Nausea and vomiting – can be difficult to control the first few hours
iii) Time course: Time of landing up to 72 hours post-landing
iv) Treatment:
1) Avoid rapid head movements, Slow but progressive increase in activity
2) Meclizine 25mg PO (pre-treatment and second dose)
3) Lower dose of promethazine (Phenergan) 6.25–12.5mg IM
v) Special considerations
1) Patient may have been pre-treated with meclizine, scopolamine or Phenergan
2) They may also have performed fluid loading with salt tablets
3) Be careful with double-dosing a patient who was pre-treated

Chapter 17. Aerospace Accident and Injuries n 209