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Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
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Elevated End-Tidal Pco2 During Long-Duration Spaceflight.

Richard L Hughson1, Nicholas J Yee, Danielle K Greaves

  • 1Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.

Aerospace Medicine and Human Performance
|September 24, 2016
PubMed
Summary
This summary is machine-generated.

Elevated carbon dioxide (CO2) in spacecraft may impact astronaut health. Studies show higher end-tidal CO2 in spaceflight, potentially linked to vision issues like VIIP.

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Area of Science:

  • Space medicine
  • Human physiology
  • Aerospace medicine

Background:

  • Elevated ambient carbon dioxide (CO2) in the International Space Station (ISS) is a potential risk factor for vision impairment intracranial pressure syndrome (VIIP).
  • Modest elevations in ambient CO2 may be compensated by normal respiratory mechanisms, but their effect on arterial CO2 requires further investigation.

Purpose of the Study:

  • To assess the difference between inspired and end-tidal CO2 in astronauts during preflight and in-flight conditions.
  • To investigate potential links between CO2 levels and VIIP in astronauts.

Main Methods:

  • Measurements of inspired and end-tidal CO2 were taken from nine male astronauts before and during a rebreathing maneuver in space.
  • Data were analyzed to compare preflight and in-flight CO2 levels.

Main Results:

  • Inspired CO2 increased from 0.6 ± 0.1 mmHg preflight to 3.8 ± 0.4 mmHg in flight.
  • End-tidal CO2 increased from 36.0 ± 3.2 mmHg preflight to 42.1 ± 3.7 mmHg in flight.
  • The increase in end-tidal CO2 (6.1 ± 1.6 mmHg) was significantly greater than the increase in inspired CO2 (3.3 ± 0.5 mmHg).

Conclusions:

  • A greater rise in end-tidal CO2 compared to inspired CO2 suggests possible alveolar hypoventilation during spaceflight.
  • Further research on arterial CO2 and acid-base balance is recommended to understand CO2's role in cerebral and retinal vasodilation and VIIP incidence.