altitude physiology

7/29/2019 Altitude Physiology

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ALTITUDE PHYSIOLOGY

TERMINAL LEARNINGOBJECTIVE

• Action: Manage the physiological effects of

altitude

• Condition: While performing as an aircrewmember

• Standard: IAW AR 95-1, AR 40-8, FM 3-

04.301, Fundamentals of Aerospace Medicine

ELO #1

• ACTION: Identify the physiological zones

and the physical divisions of theatmosphere.

• CONDITION: Given a list.

• STANDARD: IAW FM 3-04.301.

TROPOSPHERE

Sea level to flight level 300 -600 depending on temperature,latitude and season.

Physical Divisions of the Atmosphere

STRATOSPHERE

IONOSPHERE

EXOSPHERE

MOUNT EVEREST 29,028 FEET

1200 miles

600 miles

50 miles

Tropopause

Physiological Zones of theAtmosphere

EFFICIENT ZONE: Sea level to 10,000 feet

SPACE EQUIVALENT ZONE: 50,000 feet and above

DEFICIENT ZONE: 10,000 to 50,000 feet

18,000 ft

63,000 ft

Composition of the Air

• 78 Percent Nitrogen N2

• 21 Percent Oxygen• 1 Percent Other

– .03 percent CO2

ELO #2

• ACTION: Select the correct barometric

pressure at sea level.

• STANDARD: IAW FM 3-04.301

14.7PSI

Sea Level Pressure

760 mm Hg

29.92 in. Hg

Barometer / Altimeter

PERCENT COMPOSITION OFTHE ATMOSPHERE REMAINS

CONSTANT

BUT PRESSURE

DECREASES

WITH ALTITUDE

SIGNIFICANT PRESSURE ALTITUDES

ALTITUDE PRESSURE

FEET mm/HG ATMOSPHERES

0 760 1

18,000 380 1/2

34,000 190 1/4

48,000 95 1/8

63,000 47 1/16

Partial Pressure

(Dalton’s Law) 760 mm Hg

47 --- mm/Hg

95 ---190 ---

380 ---

523 ---

760 ---

78% N2

The pressure exerted by a

mixture of gases is equal to the sum of the partial pressures of each gas in the mixture.

Pt = P 1 + P 2 + ...+ Pn

(Dalton’s Law)

ELO #3

• ACTION: Identify the components of the

circulatory system that transport oxygenthroughout the human body.

FUNCTIONS OF THECIRCULATORY SYSTEM

• Oxygen and nutrient (fuel) transport to the cells.

• Transport of metabolic waste products to organ

removal sites.

• Assists in temperature regulation.

Components of the Circulatory System

Plasma

Red Blood Cell

CO2 O2

hemoglobin molecule

Blood transport of O2 and CO2

O2 molecule

ELO #4

• ACTION: Select the functions and types of

respiration.

• STANDARDS: IAW FM 3-04.301.

FUNCTIONS OF THERESPIRATORY SYSTEM

Intake of Oxygen [O2]

Removal of Carbon Dioxide [CO2]

Maintenance of body heat balance

Maintenance of body acid base balance [pH]

Phases of Respiration

Active Phase INHALATION

Passive Phase

EXHALATION

Breathing in Breathing out

COMPONENTS OF THE RESPIRATORY SYSTEM

Nasal/Oral

pharynx

Trachea

Bronchi

Bronchiole

AlveolarDucts

Alveoli

Law of Gaseous Diffusion

Gas molecules of higher pressure move in the direction of gas molecules of a lower pressure

PO2 = 100mmHg PO2 = 40mmHg

PO2 = 70 mmHg PO2 = 70 mmHg

Blood Gas Exchange

PCO2 = 46 mm

PO2 = 100 mmPCO2 = 40 mm

PO2 = 40 mm

PO2 = 100 mm

PCO2 = 40 mmPCO2 = 46 mm

PO2 = 1 - 60 mm

Arterial Capillary

Hemoglobin Saturation 98%

Venous Capillary

Hemoglobin Saturation 75%

Tissue Alveoli

Oxygen transport in the blood:

dependent on the partial pressure of oxygen .

Correction of Altitude, AlveolarO2, Hb saturation

-------- ambient air --------ALTITUDE BAROMETRIC ALVEOLAR HEMOGLOBIN

(FEET) PRESSURE OXYGEN SATURATION

(mmHg) ( PAO2) % (Hb)

Sea level 760104 97

10,000 52367 90

20,000 34940 70

30,000 226

Correction of Altitude, AlveolarO2, Hb saturation

-------- 100% Oxygen --------ALTITUDE BAROMETRIC ALVEOLAR HEMOGLOBIN

(FEET) PRESSURE OXYGEN SATURATION

(mmHg) ( PAO2) % (Hb)

Sea level 760 673 100

10,000 523 436 100

20,000 349 262 10030,000 226 139 99

40,000 141 58 87

50,000 87 16 15

ELO #5

• ACTION: Match the type of hypoxia with

their respective causes.

• CONDITION: Given a list of hypoxia typesand a list of hypoxia causes.

• STANDARDS: IAW FM 3-04.301.

Hypoxia

State of oxygen [O2] deficiency

in the blood cells and tissuessufficient to cause

impairment of function.

Types of Hypoxia

• Hypemic

• Stagnant• Histotoxic

• Hypoxic

ReducedpO2 in the lungs

(highaltitude)

Body tissue

Redblood cells

Hypoxic Hypoxia

A deficiencyin Alveolaroxygen

exchange

An oxygendeficiency

due toreduction inthe oxygen

carryingcapacity ofthe blood+

Hypemic Hypoxia

Reduced

bloodflow

movingslowly

Adequateoxygen

Red blood cells

not replenishingtissue needsfast enough

Stagnant

Hypoxia

Red blood cellsretain oxygen

Inability of thecell to accept or use oxygen

Poisoned tissue

Adequateoxygen

Histotoxic Hypoxia

H i S t

Hypoxia Symptomswhat you feel

(subjective)Air hunger

Apprehension

Fatigue

Nausea

Headache

Dizziness

Denial

Hot & Cold Flashes

Euphoria

Belligerence

Blurred Vision

Numbness

Tingling

Hypoxia Signs

• Hyperventilation

• Cyanosis

• Mental confusion

• Poor Judgment

• Lack of muscle coordination

Hypoxia Signswhat we see in you

(objective)

Stages of Hypoxia

• Indifferent Stage

• Compensatory Stage• Disturbance Stage

• Critical Stage

Indifferent Stage

• Altitudes:

– Air: 0 - 10,000 feet

– 100% O2: 34,000 - 39,000 feet

• Symptoms: decrease in night vision

@ 4000 feet• acuity

• color perception

Compensatory Stage

• Altitudes:

Air: 10,000 -

15,000 feet

100% O2: 39,000 - 42,000feet

• Symptoms: impaired efficiency,drowsiness, poor judgment anddecreased coordination

CAUTION!!!!

Failure to recognize yoursigns and symptoms may

result in an aircraft mishap.

Disturbance Stage

• Altitudes

Air: 15,000 - 20,000 FEET

100% O2: 42,000 - 44,800 FEET

Disturbance Stage symptoms

• Memory

• Judgment

• Reliability

• Understanding

• Coordination

• Flight Control

• Speech

• Handwriting

Time of Oxygen

1 Minute

2 Minutes

3 Minutes

4 Minutes

5 Minutes

6 Minutes

Put Back on Oxygen

Disturbance Stage

• Signs

– Hyperventilation

– Cyanosis

Critical Stage

• Altitudes

Air: 20,000 feet and above

100% O2: 44,800 feet and above

• Signs: loss of consciousness,convulsions and death

F t dif i h i

Factors modifying hypoxiasymptoms

• Pressure altitude

• Rate of ascent

• Time at altitude

• Temperature

• Physical activity

• Individual factors

• Physical fitness

• Self-imposed stresses

keep self imposed stresses out of the aircraft

• Drugs

• Exhaustion

• Alcohol

• Tobacco

• Hypoglycemia

ALCOHOL

Expected performance time for a crew member

flying in a pressurized cabin is reduced approximately one-half following

loss of pressurization suchas in a:

RD R apid D ecompression

E d P f

FL 430 & above 9-12 seconds FL 400 15 - 20 seconds

FL 350 30 - 60 seconds

FL 300 1 - 2 minutes

FL 280 2 1/2 - 3 minutes

Expected PerformanceTimes

Hypoxia

• Prevention

– Limit time ataltitude

– 100% O2

Hypoxia

• Treatment

– 100% O2

– Descend to a safealtitude

ELO #6

• ACTION: Select the symptoms of

hyperventilation.

• STANDARD: IAW FM 3-04.301 andFundamentals of Aerospace Medicine.

Hyperventilation (definition)

An excessive rate and depth ofrespiration leading to the abnormal

loss of CO2

from the blood.

Hyperventilation

Hyperventilation(causes)

• Emotional

• (fear, anxiety,apprehension)

• Pressure

breathing• Hypoxia

H til ti

Hyperventilation Symptoms

• tingling sensations

• muscle spasms

• hot and cold sensations• visual impairment

• dizziness

• unconsciousness

Hyperventilation reason for symptoms :

loss of carbon dioxide [CO 2 ]

shift in pH balance

Hyperventilation

significance

• incapacitation of an otherwise outstanding, healthy air crewmember

• confusion with hypoxia

above 10,000 feetpossible hypoxia

below 10,000 feetprobably hyperventilation

Hyperventilation

(distinguishing factors)

Hyperventilation

Don’t Panic

Control your breathing

Check your oxygen equipment - it may be hypoxia

Hyperventilation(corrective actions)

ELO #7

• ACTION: Select the causes and treatment

of an ear, sinus and tooth trapped gasdysbarism.

Dysbarism

Syndrome resulting from the effects,

excluding hypoxia, of a pressuredifferential between the ambient

barometric pressure and the

pressure of gases within the body.

B l ’ L

Boyle’s Law

The volume of a gas isinversely proportional to its

pressure; temperature

remaining constant.

Gas E pansion

1.8X 2.0X18,000

2.5X 25,000 3.0X

34,000 5.0X

43,000

9.5X6.0X

Gas Expansion

(prevention of gas pain)

• Watch your diet, don’t eat too fast • Avoid soda and large amounts of water just

prior to going to altitude

• Don’t chew gum during ascent

• Keep regular bowel habits; eat your fiber

Opening to throatEustachiantube

External earMiddle

Semicircularcanal

Cochlea

Auditorynerve

Anatomy of the Ear

Middle Ear Cavity

Eustachian Tube

AtmosphericPressure

TympanicMembrane

External Ear

Middle Ear Cavity

Eustachian TubeBlocked / Infected

TympanicMembrane

External EarAtmosphericPressure

Pressure Effect

Ear Block

Tympanic membrane,

(ear drum),normal

Tympanic membrane,

(ear drum),inflamed

Tympanic

membrane,

(ear drum),infected

Frontal

Ethmoid

MaxillarySphenoid

The Sinuses

Treatment of an Sinus/Ear

Treatment of an Sinus/EarBlock

Stop the descent of the aircraft andattempt to clear by valsalva.

If unable to clear, climb back to altitudeuntil clear by pressure or valsalva.

Descend slowly and clear ear frequentlyduring descent.

B d t l i

Barodontalgia

• Tooth pain due to:• Gum abscess: dull pain on ascent

• Inflamed pulp: sharp pain on

ascent

• Inflamed maxillary sinus: pain

primarily on descent

TREATMENT of

Barodontaliga

• Descend aircraft/chamber to sea level.

• Seek dental help

ELO #8

• ACTION: Identify the types and treatmentsof evolved gas dysbarsims, which occurswith altitude.

• CONDITIONS: Given a list.

• STANDARD: IAW FM 3-04.301 andFundamentals of Aerospace Medicine

Decompression Sickness(evolved gas dysbarism)Results due to the reduction in

atmospheric pressure. As pressuredecreases, gases dissolved in body fluids

are released as bubbles.

Henry’s Law

• The amount of gas

dissolved in

solution is directlyproportional to thepressure of the gas

over the solution.

Evolved Gas Disorders

• N2 bubbles becometrapped in the joints.Onset is mild, buteventually painful!

The Bends

• Paresthesia • N2 bubbles formalong nerve tracts.Tingling and itchysensation and

possibly a mottled redrash.

E l d G Di d

• The Chokes

• N2 bubbles blocksmaller pulmonary

vessels. Burningsensation in sternum.Uncontrollable desire tocough. Sense of

suffocation ensues.

E l d G Di d

• CNS • N2 bubbles affectspinal cord. Visualdisturbances,paralysis, one sided

tingling.

E l d f

Evolved gas factors

• Rate of ascent

• Altitude

• Body fat content

• Age

• Exercise

• Duration of exposure

• Repeated exposure

Decompression Sickness

Decompression Sicknessprevention

0 1 2 3 4 5

TIME IN HOURS

Denitrogenation

• Denitrogenation

• Maintain cabinpressurization

Decompression Sickness

Descend

100% Oxygen

Decompression Sicknesstreatment

Land at nearestlocation wherequalified medical

assistance isavailable.

Compression greaterthan 1 atmosphere(absolute).

AR 95 1

AR 95-1Altitude Restrictions and Oxygen Requirements

14,000

10,000

12,000

1 Hour Total30 Min Total

Unpressurized

Pressurized

10,000

14,000

25,000

Maintain Cabin PA at or below 10,000

10 Min Supply of O2 for all occupants

Crew O2 masks readily available

Supplemental Oxygen Required

AR 95-1

AR 95-1Altitude Restrictions and Oxygen Requirements

If pressurization is lost above 14,000’, an immediate

descent will be made to a cabin pressure altitude of 10,000’

or below.

Then unpressurized restrictions apply

AR 40 8

AR 40-8Flight Restrictions Due to Exogenous Factors

• Flying duty is prohibited for 24 hours after SCUBA diving

• Aircrew members will not be regular blood donors.

• After blood donation, aircrew members will berestricted from flying for 72 hours

• Performance of flying duty is prohibited for 12 hours after any altitude chamber flight

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CONCLUSION

altitude physiology

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