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I'm researching who to let onto my generational ships. I have figured that certain pre-existig inheritable medical conditions should be screened out of who makes the cut or not, focusing on hypertension, hypotension and other similar blood disorders.

I have read about hypertension and hypotension. Both are important to treat but hypotension is much more so than most cases of hypertension.

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Hypotension can cause syncope and shock. Hypertension can cause many more things but usually it is chronic. Hypotension is more acute.

I figured that if all the people that go onto the generation ship have a blood pressure in the normal range and the generation ship has artificial gravity among other things to make it a more earth-like environment, that there will be enough hypertension and hypotension as is without adding people with an already abnormal blood pressure.

And going from earth's atmosphere to space, even with artificial gravity that will prevent sickness and muscle weakness from weightlessness could be enough external force to change blood pressure. Most likely hypertension would result from external force but in some people it might actually cause hypotension.

A CNAP monitor might want to be put on every human so that blood pressure can be monitored all the time from their 18th birthday onward(childhood hypertension is rare, even among those that are overweight or obese, I certainly have never had hypertension except possibly when I have been stressed out, even when my weight was at its peak).

And hypertension in a child would likely be symptomatic. In fact if a child had chronic hypertension, I bet the child would have syncope or seizures. Adult hypertension is often asymptomatic for a long time. And I would think that vasculitities such as Kawasaki disease would be the most common cause of childhood hypertension.

So there is no practical reason to have a blood pressure monitor on a child unless the child does have a type of vasculitis or other common cause of childhood hypertension. For adults though, knowing if the hypertension is sporadic(so like stressed out or sudden increase in heart rate for some other reason) or long lasting(so hypertensive at rest for example) is super important so continuous blood pressure monitoring is practical for adults.

Should

A) Hypertension or hypotension restrict people from boarding the generation ship regardless of its cause
or
B) Those with vasculitis, bleeding, or other treatable blood pressure abnormalities be allowed, while those with more permanent abnormalities such as obesity (risk factor for hypertension) or pregnancy (risk factor for both really but especially hypotension) would not be allowed?

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    $\begingroup$ You seem to ask many medical and biological questions but they often alienate many readers. The average worldbuilder may want to help you, but they cannot do so without knowing the words/phrases hypotension, syncope, CNAP monitor, vasculitis, Kawasaki disease, etc. Please, please, please! Link to or otherwise explain topic-specific terms in your questions. $\endgroup$ – Zxyrra Feb 22 '17 at 6:40
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    $\begingroup$ Pregnancy is enough to get you banned from boarding a generation ship? $\endgroup$ – EveryBitHelps Feb 22 '17 at 13:43
  • $\begingroup$ I added an intro paragraph to the question because I had no idea what I was reading about for the first few paragraphs. Feel free to remove or edit it if you don't agree with it. $\endgroup$ – EveryBitHelps Feb 22 '17 at 13:53
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    $\begingroup$ Pregnancy is a permanent abnormality? I'm (a) offended and (b) laughing. $\endgroup$ – MissMonicaE Feb 22 '17 at 17:27
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tl;dr Healthy blood pressure is part of the broader health exam; it's necessary, but not special

Space has plenty of effects on the body, both in the short and long term. Isolation, as well as stress and a lack of gravity, can cause serious changes. Space agencies screen candidates for mental and physical fitness in order to make sure they will be safe in space, so health is already a prerequisite; expect safe blood pressure to be on the table in addition to other checks.

In regards to your second option - yes, of course a thorough medical exam is warranted! No matter what your criteria is, it will probably involve checking to see if people are healthy. If you discover an ailment, you will probably patch it up regardless of if you want to send the person to space, so you might as well consider it part of the process. Fix it if you can.

It's not exactly clear how blood pressure changes in space. Some sources claim it decreases, while others claim it increases. All the more reason to find or produce healthy people.

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Existing hyper- or hypotension would be a good elimination criteria for a pre-boarding exam, but since there are many causes for both; to include lifestyle, genetics, diet, tumors, age related illness, other organ dysfunction, medications, etc it is not a very specific indicator of actual poor health in isolation. And many times blood pressure can be well controlled through lifestyle or medication with no significant negative effects.

Many folks develop hypertension as they age, so screening them on admission to the ship will do little to ensure they don't develop it later on (depending on how advanced your medical system is). So if you are trying for some sort of eugenics program and eliminating known genetic illnesses then this one would be very difficult to eliminate (though with a large enough starting pool and a rigorous family history genetic questionnaire, it could be done). But there will still be other causes of blood pressure dysfunction like hormone secreting tumors, renal artery stenosis, renal dysfunction, and response to diet and medications for other things.

But really, even with an Earth normal gravity/radiation situation on your generation ship, there may be FAR more pressing medical concerns for the crew than blood pressure irregularities. The monotonous diet, potential vitamin/mineral deficiencies, close quarters environment, air/water recycling, and numerous unavoidable allergen exposures within a small closed system like a spaceship are gonna wreck havoc on your population in any number of unknowable ways (unless you conduct some large scale prolonged simulations). Just the psychological issues alone may force you to accept physically weaker folks because they are the ones with the mental fortitude to be able to deal with chronic stress.

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  • $\begingroup$ The entirety of your post speaks to why the first sentence is not true. $\endgroup$ – Willk Feb 22 '17 at 17:54
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It seems unlikely that blood pressure would be under any circumstances the primary criteria for a generation ship. Same with most underlying reasons for hypertension. It would at best IMHO be one of hundreds of secondary criteria that influence the final suitability value.

What this means in practical terms is that in any case where hypertension might make the difference the person would be close enough to making it that a detailed medical would make sense. This is because people without hypertension might actually have worse medical issues that do require an examination to detect.

Assuming that the aliens want to get the absolute best value, of course. In some cases it is perfectly sensible to save resources in the selection process even if that results in non-optimal results. Especially if dealing with large numbers.

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I suffered from hypotention a great deal as a young woman. You wouldn't want me on there. Although most of the time I did ok there were times I could barely get out of bed.

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