Cardiopulmonary Physiology - University Of Maryland...Cardiopulmonary Physiology ENAE 697 - Space...

Cardiopulmonary Physiology ENAE 697 - Space Human Factors and Life Support

U N I V E R S I T Y O FMARYLAND

Cardiopulmonary Physiology• Discussion of the project for the Physiology section!• The cardiovascular system!• Gravitational effects!• Acceleration effects!• G-induced loss of consciousness!• The pulmonary system!• Oxygen transport!• Effects of altitude

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© 2013 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu

http://spacecraft.ssl.umd.edu



Space Physiology Assignment• This unit covers five topics!

– Cardiopulmonary system!– Musculoskeletal system!– Neurovestibular system!– Decompression!– Radiation effects!

• Find papers relevant to human space flight in two of these areas!

• Post the papers and a one-page synopsis of each to the Canvas site for this course!

• No duplications! (It’s good to do this early.)!• Due Feb. 16

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The Human Circulatory System

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Blood Pressure in Circulatory System

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Gas Exchange in the Lungs

From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

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Gas Exchange in the Tissues


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Gravity Effects on Arterial Pressure

120/80 mmHg

95/55 mmHg

210/170 mmHg

320 mm

1200 mm

1000 mmH2O = 74.1 mmHg

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The Human Circulatory System, Revisited

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Cardiovascular Regulatory System

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In-Flight Change in Leg Volume

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In-Flight Change in Body Mass

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Change in Leg Volume (Skylab)

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Lower Body Negative Pressure (LBNP)

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Cardiovascular Effects of Microgravity• Cardiovascular deconditioning!• Upper body blood pooling!• Changes in blood volume!• Increased calcium content

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Acceleration Effects on Arterial Pressure

120/80 mmHg

25/–– mmHg

475/435 mmHg

320 mm

1200 mm

At 4 g’s longitudinal:1000 mmH2O = 296 mmHg

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Inertial Acceleration Nomenclature+gx (forward) “transverse anterior-posterior G”, “supine G”, “eyeballs in”!-gx (rearward) “transverse P-A G”, “prone G”, “eyeballs out”!+gz (headward) “positive G”, “eyeballs down”!-gz (footward) “negative G”, “eyeballs up”!+gy (to left) “right lateral G”, “eyeballs right”:!-gy (to right) “left lateral G”, “eyeballs left”

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Tolerance to Sustained Acceleration

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Variation in G Tolerance

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F-16 seat orientation, gradual onset, no G-suit



G Tolerance to ACM (PLL Criteria)

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Sustained Linear G Limits (+Gx)

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Sustained Linear G Limits (-Gx)

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Sustained Linear G Limits (+Gz)

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Sustained Linear G Limits (-Gz)

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U N I V E R S I T Y O FMARYLAND 24



Symptomatology of GLOC

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A. G/sec rate of onset!B. Asymptomatic

(eye/brain tissue reserves) !

C. GLOC!D. Blackout!E. Light loss!F. Asymptomatic

(vasoconstriction)



The Human Respiratory System

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Lung Measurements


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Respiratory Volume vs. Exertion

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VO2 Metabolic Workload Measurement

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VO2 Measurement in (Simulated) Suit

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Metabolic Processes• Respiratory Quotient (“RQ”)!""

• Function of activity and dietary balance!– Sugar:!– Protein:!– Fat:!

• For well-balanced diet, RQ~0.85

€

RQ =Exhaled volume of CO2Inhaled volume of O2

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C6H12O6 + 6O2 → 6CO2 + 6H 2O RQ =1.0( )

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2C3H 7O2N + 6O2 → 5CO2 + 5H2O RQ = 0.83( )

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C57H104O6 + 80O2 → 57CO2 + 52H2O RQ = 0.71( )

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Gas Exchange in the Lungs


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Gas Exchange in the Tissues


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Partial Pressures of Gases in Respiration

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Respiratory Gas ppO2 ppCO2 ppN2 ppH2O Total

Inspired Air 159 0.3 595 5.7 760

Tracheal Air 149 0.3 563.7 47 760

Expired Air 116 32 565 47 760

Alvolar Air 100 40 573 47 760Arterial Blood 95 40 573 47 755

Venous Blood 40 46 573 47 706

Tissues ≤40 ≥46 573 47 ≤706



Respiratory Problems• Hypoxia!

– Hypoxic!– Hypemic!– Stagnant!– Histotoxic!

• Hyperoxia!• Hypocapnia!• Hypercapnia

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Types of Hypoxia• Hypoxic (insufficient O2 present)!

– Decompression!– Pneumonia!

• Hypemic (insufficient blood capacity)!– Hemorrhage!– Anemia!

• Stagnant (insufficient blood transport)!– Excessive acceleration!– Heart failure!

• Histotoxic (insufficient tissue absorption)!– Poisoning

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Effects of Altitude on Respiration

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Altitude (m) SL 3700 5500 6700 7600

Altitude (ft) SL 12,000 18,000 22,000 25,000

Volumetric Rate (L/min) 8.5 9.7 11.1 15.3 –

Respiratory Rate (per minute) 12 14 12 15 –

Tidal Volume (L) 0.71 0.69 0.92 1.02 –

Alveolar ppO2 103 54.3 37.8 32.8 30.4

Alveolar ppCO2 40 33.8 30.4 28.4 27



Pressure Effects on Blood Oxygenation

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Pressure Effects on Blood Oxygenation

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Blood Oxygen Saturation with Altitude

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Hypoxia Effective Performance Time


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Effects of Supplemental Oxygen


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Effective Performance Time at Altitude

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Altitude, m Altitude, ft Effective Performance Time5500 18,000 20-30 minutes6700 22,000 10 minutes7600 25,000 3-5 minutes8500 28,000 2.5-3 minutes9100 30,000 1-2 minutes

10,700 35,000 0.5-1 minute12,200 40,000 15-20 seconds13,100 43,000 9-12 seconds15,200 50,000 9-12 seconds



Oxygen Toxicity


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Effects of ppCO2

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From James T. Joiner, NOAA Diving Manual, Fourth Edition, 2001



Acute Effects of Hyperventilation

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From James T. Joiner, NOAA Diving Manual, Fourth Edition, 2001

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