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•Elevation : 8,854 m or (29,050 ft)

•First ascent : May 29, 1953

•First ascenders: Tenzing Norgay, Edmund Hillary

•Mountain range: Himalayas, Mahalangur Himal

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Dr. Jitendra Patel (MBBS, MD, ACME, Ph.D…)

Medical Educator, Researcher & Academic Administrator

Associate Professor, Department of Physiology

Email: dr.jrpatel84@gmail.com Web: www.esphys.weebly.com

Competency

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No. PY6.4 & 6.5 (Respiratory Physiology)

CompetencyDescribe and discuss the physiology of high altitude. Describe and discuss the oxygen therapy and acclimatization.

D/L/Core K/KH/Y

AM Written/Viva voce

Integration No

Imp. Concept Problem and its solution in HAP

Phy. TriviaDefence Institute of Physiology & Allied Sciences (DIPAS)

OUTLINE

• Introduction

• Basic concept & problem

• Clinical syndrome

• Physiological compensatory mechanism

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Introduction

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ALTITUDE TYPEFROM SEA-LEVEL

(In feet)

HIGH 8,000 – 12,000

VERY HIGH 12,000 – 18,000

EXTREMELY HIGH Above 18,000

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My definition of Altitude (life)

Altitude = Goal/Attitude

Satisfaction > Success

SIGNIFICANT ATMOSPHERIC PRESSURE VARIATION WITH ALTITUDE:

ALTITUDE PRESSURE

(FEET) ( mm of Hg) (Atmospheric unit)

0 760 1

18,000 380 1/2

34,000 190 1/4

48,000 95 1/8

63,000 47 1/16

Basic Concept

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• Human body is specifically designed in such a way

that it delivers adequate O2 to the tissues only

when oxygen is supplied at a pressure close to the

sea-level (P = 760 mm Hg PO2 =159 mm Hg).

• So, at high altitude there is hypoxic hypoxia

tissue oxygenation suffers physiological

derangements.

“Connecting a 24 volt motor to a 6 volt battery” :P

Basic Problem

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• Decreased pO2

• Increased Volume

• Decreased temperature

• Effect of light rays

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

0 (sea-level) 160 ~ 97 %NIL

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

0 (sea-level) 160 ~ 97 %NIL

Upto 10,000(3,000)

110 ~ 90 %Usually none,

( of indifference)

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

0 (sea-level) 160 ~ 97 %NIL

Upto 10,000(3,000)

110 ~ 90 %Usually none,

( of indifference)

10,000 –15,000

(3,000 –4,500)

98 ~ 80 %

Mod. Hypoxic symptomscardiorespiratory manifestaions & early

CNS involvements ( of reaction)

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

0 (sea-level) 160 ~ 97 %NIL

Upto 10,000(3,000)

110 ~ 90 %Usually none,

( of indifference)

10,000 –15,000

(3,000 –4,500)

98 ~ 80 %

Mod. Hypoxic symptomscardiorespiratory manifestaions & early

CNS involvements ( of reaction)

15,000 –20,000

(4,500 –6,000)

70 < 70 %Severe hypoxic symp aggravated CNS

involvement (of disturbance)

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ALTITUDE LEVEL

INSPIRED AIR PO2

Hb-SATURATION EFFECTS

Feet (meter) In mm of Hg in % Stages (if any)

0 (sea-level) 160 ~ 97 %NIL

Upto 10,000(3,000)

110 ~ 90 %Usually none,

( of indifference)

10,000 –15,000

(3,000 –4,500)

98 ~ 80 %

Mod. Hypoxic symptomscardiorespiratory manifestaions & early

CNS involvements ( of reaction)

15,000 –20,000

(4,500 –6,000)

70 < 70 %Severe hypoxic symp aggravated CNS

involvement (of disturbance)

Above 20,000 &

onwardsFurther falls below 60 %

Unconsciousness & alarmingdeterioration survival impossible

without supplemental O2 (critical survival altitude)

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Effects depend upon….. (LSD)

1. The level of altitude

2. Rapid or slow ascent

3. Duration of exposure

Acute mountain sickness

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Sea level resident ascending within 1-2 days

1) Acute cerebral edema

2) Acute pulmonary edema

Acute cerebral edema

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Acute cerebral edema…….

• Hypoxia → cerebral VD → ↑ capi. Pressure →

cerebral edema → Headache, nausea,

vomiting, irritability, disorientation,

dysfunction.

High Altitude Pulmonary Edema

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• Rapid ascent usually above 10000 ft.

• Heavy physical work during 1st 3-4 days.

• Mechanism;

– Sympathetic over activity due to hypoxia/Cold

temperature.

– Causes VC – ↑Pulmonary capi hydrostatic pressure.

– Causes pulmonary edema.

Chronic mountain sickness (Monge’s dis.)

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Long Term Residents of High Altitude

↑ ↑ ↑ RBC

↑ ↑ Pulmonary artery pressure (PAP).

Enlargement & failure of right heart.

↓ Systemic arterial pressure.

CCF, Death.

Treatment of high altitude illness

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Individual should be brought to low altitude at the

earliest and rest

Treatment of pulmonary and cerebral oedema:

• O2 therapy

• Diuretics

• Steroids

• Nifedipine

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Physiological responses to high altitude

Acute responses (Accommodation)

Long term responses (Acclimatization)

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Accommodation

• Immediate reflex adjustments of RS & CVS

–Hyperventilation

–Tachycardia

– Increased 2-3 DPG

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Acclimatization

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• “Getting used to…”

• People remaining at high altitudes for days, weeks

or years become more and more acclimatized to

low PO2.

• This causes the hypoxia to cause fewer deleterious

effects on their bodies.

• They can thus work harder at higher altitudes

without hypoxic effects.

Acclimatization…cont

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After a long term exposure to hypoxia

Increase in ventilation;

• Stimulation of respiratory centers by

peripheral chemoreceptors.

Increased RBC count;

• Hypoxia stimulates erythropoiesis.

Acclimatization…cont

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After a long term exposure to hypoxia

Increased TLC & diffusing capacity of lungs;

• ↑Pulmo. Capi. Suface area due to ↑ pulm. Blood volume

• ↑Lung air volume

• ↑Pulm. Arterial pressure

Increased vascularity of the peripheral tissues;

• Angiogenesis

Increased O2 usage by cells despite less pO2.

Natural Acclimatization

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This occurs in people

living from their birth at

high altitudes.

Those living in the Andes

& Himalayan mountains,

for instance.

Acclimatization begins in

them in infancy.

Effects:-

↑chest size

↓ body size

↑ Rt. Heart

↑ O2 delivery to the tissues

(↑Hb)

↑ work capacity (87%)

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Physiology Trivia

Defence Institute of Physiology & Allied Sciences (DIPAS)

Established on 20th September 1962. In India,

research in military physiology was initiated in the year

1950 through a small group of scientists and medical

physiologists within the realm of Defence Science

Laboratory, Delhi.

http://drdo.gov.in/drdo/labs/DIPAS/English/index.jsp?pg

=homebody.jsp

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ANS: C

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ANS: A

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ANS: B

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ANS: B

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ANS: A

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