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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 deep sea diving. Describe and discuss the decompression sickness.

D/L/Core K/KH/Y

AM Written/Viva voce

Integration No

Imp. Concept Problem and its solution in DSP

Phy. Trivia H/O Brooklyn Bridge

OUTLINE

Introduction

Physiological problem

Decompression sickness

Preventive measures

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Barometric Pressure Changes

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For every 10 m below the water surface(sea water) you go, the barometricpressure increases by 1 atm.

Total barometric pressure;

= (Pressure due to water) + (Pressure due to air)

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Gas Volume changes

Boyle’s law: P α 1/V

As the pressure increases volume of gas decreases.

1 lit

½ lit

¼ lit

1/8 lit

Sea level

33 ft

100 ft

233 ft

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Conditions of High Barometric pressure is met.......

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• Deep sea diving

• Submarines

• Caisson’s workers;

Those who dig underwater tunnels,

work in chamber (caisson’s chamber).

Physiological Problems

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Can be categorized…….

1. At depth - Due to compression

2. During ascent - Due to decompression

Compression and decompression of gas over liquid

Physiological Problems At Depth

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Partial pressure of O2, CO2 & N2 is increased

↑ pO2 (3000 mm Hg @ 4 Atm P)

[More free radicals = O2- ]

• Acute O2 toxicity

CNS complications : Disorientation, convulsions, coma

• Chronic O2 toxicity (8-24 hr @ 1-1.5 Atm P)

Lung congestion & edema

Physiological Problems At Depth

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• ↑ pN2

– Nitrogen dissolves in body fluids & fats specially

neurons of brain.

– Decreases excitability of neurons – Nitrogen narcosis.

• Euphoria,↓ mental functions, drowsiness, poor muscle

co-ordination.

Physiological Problems During Rapid Ascent

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1. Decompression sickness/

Caisson’s disease/

Dysbarism/

Bends/

Diver’s palsy.

2. Air embolism

Decompression sickness

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• Nitrogen forms bubbles & escapes from the

tissues;

• Bubbles block blood vessels;

• Tissue ischemia & tissue death.

Decompression sickness….cont

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• Symptoms

– Pain in joints & muscles of legs or arms – Bends

– Chokes – Shortness of breath

– Paralysis of muscles – Diver’s palsy

– Coronary ischemia or MI

– Neurological symptoms: Dizziness, Collapse, Unconsciousness

– Death

• Treatment – Tank decompression

Air embolism

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• Chest pain

• Tachycardia

• Hypotension

• Block the blood flow

• Death

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Preventive measures

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1. Use of breathing

apparatus:

open/closed circuit

• SCUBA diving; self-

contained underwater

breathing apparatus.

Preventive measures....cont

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2. Use of breathing mixture containing

helium & low O2

– Prevents O2 toxicity

– Helium;

• Easy to breath

• Fast diffusion

• Easy elimination of bubbles

• Less toxic than nitrogen

Preventive measures.....cont

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3. Slow ascent or decompression tank

• Principle: slow ascent

• Person is put into a pressurized tank.

• Decompression ;

30 m depth × 30 min dive…………NA

60 m depth × 60 min dive…………3 hours

100 m depth × 20 min dive……….3 hours

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Physiology Trivia

History

• In 1873: Dr. Andrew Smith first utilized the term

"caisson disease" describing 110 cases of decompression

sickness as the physician in charge during construction of

the Brooklyn Bridge.

• In1916: The decompression chamber was invented by

the Italian engineer Alberto Gianni.

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Address: Brooklyn Bridge, New York, NY 10038, USA

HIGH-YIELD TOPICS IN RS PHYSIOLOGY

1. Non-respiratory function of RS

2. Pressure and Volume changes during Rs

3. Pulmonary compliance

4. Surfactant

5. PFTs

6. Ventilator-perfusion ratio

7. Respiratory membrane

8. Transport of gases

9. Regulation of respiration

10. Hypoxia

11. Acclimatization

12. Dysbarism

13. Periodic breathing

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