Hyperbaric Hyperbaric environment.environment.

-Mathew -Mathew YesudhasYesudhas

Introduction Introduction

►An environment in which the pressure An environment in which the pressure is greater than at sea level is known as is greater than at sea level is known as hyperbaric environment.hyperbaric environment.

►This environment increases the This environment increases the pressure of the gases contained in the pressure of the gases contained in the Para nasal sinuses, the respiratory Para nasal sinuses, the respiratory tract, GI tract and the gas dissolved in tract, GI tract and the gas dissolved in body fluids.body fluids.

►When you descent to the depth in under water, When you descent to the depth in under water, the water exerts an additional 760mmHg, the water exerts an additional 760mmHg, because water is denser than air. because water is denser than air.

► E.g., a balloon that is filled with air shrinks E.g., a balloon that is filled with air shrinks rapidly when it is pushed only a few feet below rapidly when it is pushed only a few feet below the water surface. the water surface.

► Even above water, the air we breathe is under Even above water, the air we breathe is under the pressure of the weight of the atmosphere.the pressure of the weight of the atmosphere.

► The volume and pressure are inversely related, The volume and pressure are inversely related, so as pressure increases volume decreases. so as pressure increases volume decreases.

► If you continue to descend to greater depths, If you continue to descend to greater depths, the gas volume becomes progressive smaller.the gas volume becomes progressive smaller.

► Also air taken into the lungs at depth will Also air taken into the lungs at depth will expand to twice ex original volume by the time expand to twice ex original volume by the time you reach the water surface. you reach the water surface.

►Consider: It would be extremely Consider: It would be extremely dangerous to take deep breathe an then dangerous to take deep breathe an then hold his breathe as you accent to the hold his breathe as you accent to the surface. surface.

►As you accent the air would expand in As you accent the air would expand in your lungs. your lungs.

►Before you reached the surface your Before you reached the surface your lungs would over distend, rupturing the lungs would over distend, rupturing the alveoli and causing pulmonary alveoli and causing pulmonary hemorrhage and lung collapse.hemorrhage and lung collapse.

►This condition is known as spontaneous This condition is known as spontaneous pneumothorax.pneumothorax.

Cardiovascular response to Cardiovascular response to water immersionwater immersion

►Water immersion reduces the stress on the Water immersion reduces the stress on the cardiovascular system. Immersing the body cardiovascular system. Immersing the body to the neck applies pressure to the lower to the neck applies pressure to the lower body to tend to minimize blood pooling and body to tend to minimize blood pooling and facilitate blood return to the heart thus facilitate blood return to the heart thus reducing cardiovascular system work.reducing cardiovascular system work.

► Also cold water decreases both the resting Also cold water decreases both the resting and exercise heart rate during immersion. and exercise heart rate during immersion.

► This causes irregularity in cardiac This causes irregularity in cardiac conduction and increases effect conduction and increases effect significantly. significantly.

► Thus diving in cold water is associated with Thus diving in cold water is associated with greater bradycardia and a higher incidence greater bradycardia and a higher incidence of cardiac arrhythmias.of cardiac arrhythmias.

Health risks Health risks

► I) Oxygen poisoningI) Oxygen poisoning

► Underwater diving increases the PO2 in inspired air Underwater diving increases the PO2 in inspired air which forces enough oxygen into solution in the which forces enough oxygen into solution in the plasma that the dissolved oxygen can supply the plasma that the dissolved oxygen can supply the metabolic needs of the diver, resulting in less metabolic needs of the diver, resulting in less oxygen unloading from the Hb at the tissues., oxygen unloading from the Hb at the tissues., because of this the HB in venous blood remains because of this the HB in venous blood remains saturated with oxygen.saturated with oxygen.

► Similarly carbon dioxide does not bind with HB that Similarly carbon dioxide does not bind with HB that is fully saturated with oxygen, therefore reduced is fully saturated with oxygen, therefore reduced oxygen unloading impairs CO2 elimination.oxygen unloading impairs CO2 elimination.

► This condition that results from excessive oxygen is This condition that results from excessive oxygen is called oxygen poisoning.called oxygen poisoning.

Decompression sickness:Decompression sickness:

► High partial pressure of nitrogen during diving High partial pressure of nitrogen during diving forces more nitrogen into the blood and forces more nitrogen into the blood and tissues. If the diver attempts to ascend rapidly, tissues. If the diver attempts to ascend rapidly, the additional nitrogen cannot be releasedthe additional nitrogen cannot be released

► From lungs in that particular short time, and From lungs in that particular short time, and this additional nitrogen gets trapped as this additional nitrogen gets trapped as bubbles in the circulatory system and tissues. bubbles in the circulatory system and tissues. This causes severe discomfort and pain and is This causes severe discomfort and pain and is referred as decompression sickness.referred as decompression sickness.

► Treatment: placing the diver in an Treatment: placing the diver in an recompression chamber.recompression chamber.

Nitrogen narcosis (rapture of the Nitrogen narcosis (rapture of the deep): deep):

►Although nitrogen is not metabolically Although nitrogen is not metabolically active, but at high pressures it act active, but at high pressures it act much like as anesthetic gas. Resulting much like as anesthetic gas. Resulting in a condition called as nitrogen in a condition called as nitrogen narcosis.narcosis.

Ruptured ear drum:Ruptured ear drum:

►Failure to equalize air pressure Failure to equalize air pressure between the sinuses and middle air between the sinuses and middle air creates unequal pressure against the creates unequal pressure against the ear drum, causing considerable pain. ear drum, causing considerable pain.

►Under severe conditions as during Under severe conditions as during ascent and descent in deep water, an ascent and descent in deep water, an inability the equalize pressure can inability the equalize pressure can rupture the eardrumrupture the eardrum

Spontaneous pneumothoraxSpontaneous pneumothorax

Microgravity environmentMicrogravity environment

INTRODUCTIONINTRODUCTION

►Microgravity refers to reduced gravity, Microgravity refers to reduced gravity, so the term is used to describe any so the term is used to describe any condition where the gravitational force condition where the gravitational force is less than that of the earth.is less than that of the earth.

►Microgravity environment mimics the Microgravity environment mimics the detraining responses seen in the detraining responses seen in the athletes during periods of inactivity or athletes during periods of inactivity or immobilization or with the aging immobilization or with the aging process.process.

Physiological alterations:Physiological alterations:

► muscle muscle

► bonebone

►cardiovascular functioncardiovascular function

Muscle Muscle

►Muscle atrophy results primarily from Muscle atrophy results primarily from decreased protein synthesis. decreased protein synthesis.

►Thus moving in space causes Thus moving in space causes reduction of protein synthesis for up to reduction of protein synthesis for up to 50% within several hours in space, 50% within several hours in space, leading to net loss muscle protein.leading to net loss muscle protein.

Bone Bone

►Microgravity results in bone mineral Microgravity results in bone mineral loss of about 4% in weight bearing loss of about 4% in weight bearing bones, but the magnitude of this bones, but the magnitude of this responses depends on the length of responses depends on the length of exposure. exposure.

►This bone mineral loss is usually This bone mineral loss is usually considered due to loss of calcium in considered due to loss of calcium in urine and faeces while in space.urine and faeces while in space.

Cardiovascular function:Cardiovascular function:

► Microgravity environment stimulates the reduction of Microgravity environment stimulates the reduction of plasma volume.plasma volume.

► In micro gravity environment, there is reduced In micro gravity environment, there is reduced hydrostatic pressure, therefore blood no longer pools hydrostatic pressure, therefore blood no longer pools in the lower extremity as it happens on earth. As a in the lower extremity as it happens on earth. As a result more blood returns to heart leading to result more blood returns to heart leading to increase in cardiac output and arterial blood increase in cardiac output and arterial blood pressure.pressure.

► These increases are accompanied by an increase in These increases are accompanied by an increase in the arterial pressure to the kidneys, which in turn the arterial pressure to the kidneys, which in turn causes the kidneys to excrete excess amount. This causes the kidneys to excrete excess amount. This response to increased blood pressure is referred to response to increased blood pressure is referred to as pressure diuresis. These adaptations are essential as pressure diuresis. These adaptations are essential to allow the body to regain its control over blood to allow the body to regain its control over blood pressure.pressure.

Exercise as counter measure to Exercise as counter measure to microgravity:microgravity:

► The astronaut has remarkable ability to adapt to The astronaut has remarkable ability to adapt to this unique environment, allowing normal or near this unique environment, allowing normal or near normal function in microgravity. normal function in microgravity.

► But several of these adaptations pose potential But several of these adaptations pose potential problems when on returning to earth.problems when on returning to earth.

► The reductions in muscle, bone and cardiovascular The reductions in muscle, bone and cardiovascular regulation of blood pressure.regulation of blood pressure.

► Possible decrease in strength and increased Possible decrease in strength and increased postural hypotension are the major concerns postural hypotension are the major concerns because of the potential problems they present on because of the potential problems they present on landing. landing.

► Like what if the astronaut could’nt get out of their Like what if the astronaut could’nt get out of their space vehicle in the event of a crash or a fire? space vehicle in the event of a crash or a fire?

► Thus exercise may be one of the most effective Thus exercise may be one of the most effective countermeasures towards microgravity.countermeasures towards microgravity.

Health risk of microgravity:Health risk of microgravity:

► A number health risks associated with A number health risks associated with microgravity are known with the changes in microgravity are known with the changes in muscle, bone and cardiovascular functions.muscle, bone and cardiovascular functions.

► Other health risk of microgravity include:Other health risk of microgravity include:

Exposure of radiation Exposure of radiation

Serious illness that cannot be treated because Serious illness that cannot be treated because of the inability to abort the mission.of the inability to abort the mission.

Psychological distress.Psychological distress.

Disturbance in control of posture and Disturbance in control of posture and locomotion.locomotion.

Any ?Any ?

Thank you..Thank you..