X-Message-Number: 21168
Date: Fri, 14 Feb 2003 13:06:17 +0100
From: Henri Kluytmans <>
Subject: Respirocytes as in vivo SCUBA device

Kennita Watson wrote :

>Assume that *all* a respirocyte could do were to store
>compressed oxygen and release it at a controlled rate.
>Has anyone posited an estimate of how long an injection
>(IV infusion, lungful, time-release capsule, skin patch,
>whatever) of them would allow a person to breathe

Yes. Robert Freitas who created the design for these devices has
also worked out such details. :)

I quote :

"Respirocytes could serve as an in vivo SCUBA (Self-Contained Underwater
Breathing Apparatus) device. With an augmentation dose or nanolung, the
diver holds his breath for 0.2 - 4 hours, goes about his business
underwater, then surfaces, hyperventilates for 6-12 minutes to recharge,
and returns to work below. (Similar considerations apply in space
exploration scenarios.)"

His number for the maximum augmentation dose :

"Infusion of 1 liter (~asymptomatic blood loss limit [97], ~plasma volume 
increase in high-altitude-adapted people [95], ~hemodilution limit for
freshwater aspiration in the lungs [98], ~splenic capacity) of 50%
respirocyte suspension raises total oxygen carrier volume to 55% of blood
volume (RBC hct ~46% plus respirocrit ~9%), after absorption of water from
the blood equal in volume to the infusion." 

So the short answer is : 4 hours with a 1 liter 50% dose.

(And using these kind of artificial devices will even relieve decompression 
sickness or caisson disease from being a danger.)

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