Diving Physiology Phases and Risks

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Questions and Answers

Rapid or deep compression can lead to neurological and physiological symptoms due to the CNS reacting negatively to ______.

increased pressure

One of the symptoms of increased pressure is ______, which is often accompanied by nausea and vomiting.

dizziness

To prevent issues related to increased pressure, it's advised to take breaks at various ______.

depths

Oxygen toxicity can occur when breathing O2 at ______ pressures.

<p>high</p> Signup and view all the answers

Symptoms of oxygen toxicity can initially present as ______, followed by visual disturbances.

<p>nausea</p> Signup and view all the answers

During the ______ phase, a diver goes deeper underwater experiencing increased pressure.

<p>compression</p> Signup and view all the answers

Nitrogen buildup does not cause issues during the dive but becomes problematic during the ______ phase.

<p>decompression</p> Signup and view all the answers

A diver should not exceed an ascent rate of ______ meters per minute.

<p>10</p> Signup and view all the answers

During the ______ phase, the diver remains at a constant depth and experiences no significant physiological changes.

<p>isopression</p> Signup and view all the answers

When ascending, previously compressed gases expand, which can lead to ______ if not managed correctly.

<p>barotrauma</p> Signup and view all the answers

Equalizing ear pressure is crucial to avoid discomfort during the compression of body ______.

<p>cavities</p> Signup and view all the answers

Breath-hold ascends can cause pulmonary ______ as air gets trapped in the lungs.

<p>barotrauma</p> Signup and view all the answers

The deeper a diver goes, the more gases like ______ dissolve into fat tissues.

<p>nitrogen</p> Signup and view all the answers

Failure in decompression procedure can lead to decompression sickness, where dissolved gases form ______ in tissues.

<p>bubbles</p> Signup and view all the answers

The mechanism of decomposition sickness involves saturation by inert gas, which begins during the ______ phase.

<p>descent</p> Signup and view all the answers

Entering the water feet first is safer than head first to avoid hyperextension of the ______.

<p>spine</p> Signup and view all the answers

Common ascension problems include sinus problems, ear problems, and ______ gas emboli.

<p>arterial</p> Signup and view all the answers

Physical and mental fitness, having a buddy, and proper dive planning are important ______ precautions.

<p>safety</p> Signup and view all the answers

The symptoms of type 1 decompression syndrome include fatigue, joint pain, and skin ______.

<p>rashes</p> Signup and view all the answers

Recompression therapy is used to decrease bubble size and relieve ______.

<p>symptoms</p> Signup and view all the answers

Nitrogen narcosis is caused by the increased pressure of nitrogen dissolved in the ______ during deep dives.

<p>bloodstream</p> Signup and view all the answers

To prevent nitrogen narcosis, divers can replace nitrogen with ______ in their breathing mix.

<p>helium</p> Signup and view all the answers

Signs of cerebral DCS include hemiplegia, visual disturbances, and confusion, which result from occlusion of cerebral ______.

<p>vascular beds</p> Signup and view all the answers

Obesity and uncontrolled diabetes are conditions that can affect a diver's fitness to ______.

<p>dive</p> Signup and view all the answers

High pressure nervous syndrome (HPNS) occurs at great ______.

<p>depth</p> Signup and view all the answers

Decompression sickness symptoms can begin as soon as ______ minutes after surfacing.

<p>10</p> Signup and view all the answers

Treatment for decompression sickness often involves the patient breathing 100% ______ during recompression therapy.

<p>oxygen</p> Signup and view all the answers

Flashcards

Compression Phase

The dive phase when the diver goes deeper underwater, experiencing increased pressure. This causes gasses like nitrogen to dissolve into the blood and tissues.

Isopression Phase

The dive phase when the diver remains at a constant depth, experiencing no change in pressure. The body is under steady pressure, and no significant physiological changes occur.

Decompression Phase

The dive phase when the diver ascends back to the surface, experiencing decreased pressure. This causes gasses to come out of solution, and if done too quickly, can lead to decompression sickness.

Decompression Sickness

A condition that occurs when gasses come out of solution too quickly during the decompression phase, forming bubbles that can obstruct blood flow. This can cause pain, paralysis, and other serious problems.

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Recommended Ascend Rate

The rate at which a diver should ascend during the decompression phase. A safe rate ensures that gasses are released gradually, preventing decompression sickness.

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Barotrauma

An injury that occurs due to changes in pressure, especially in body cavities like the lungs and sinuses.

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Lung Overexpansion

A type of barotrauma that occurs in the lungs when the diver ascends too quickly, causing the air in the lungs to expand rapidly.

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Pulmonary Barotrauma

A type of barotrauma that can occur when a diver holds their breath during ascent, causing the air in the lungs to expand and potentially rupture.

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Rapid Compression

The process of the central nervous system responding negatively to rapid increases in pressure, leading to symptoms like dizziness, nausea, and decreased cognitive function.

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Oxygen Toxicity

A condition caused by breathing oxygen at high pressure, leading to CNS and lung problems.

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CNS Oxygen Toxicity

The primary type of oxygen toxicity affecting the central nervous system, characterized by seizures.

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Pulmonary Oxygen Toxicity

The type of oxygen toxicity that affects the lungs, leading to respiratory distress.

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Nitrogen Addition

A technique used to prevent rapid compression symptoms by adding nitrogen to the breathing gas to stabilize the nervous system.

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Decompression Sickness (DCS)

A condition that occurs when dissolved gases, primarily nitrogen, form bubbles in the tissues due to a rapid decrease in pressure, typically during ascent from a dive.

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Decompression Syndrome Type 1

A type of DCS characterized by fatigue, joint and muscle pain, skin rashes, and "skin beds" (pain in joints and skin).

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Decompression Syndrome Type 2

A more severe type of DCS involving neurological, respiratory, and cardiovascular symptoms, including clouded thinking, numbness, weakness, paralysis, rash, and poor balance.

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Recompression Therapy for DCS

A treatment for DCS that involves recompression therapy, which aims to reduce the size of nitrogen bubbles by increasing pressure and providing 100% oxygen.

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Cerebral Arterial Gas Embolism (CAGE)

A condition that arises from the introduction of air bubbles into the arterial blood due to pulmonary barotrauma, causing a sudden disruption in blood flow and leading to several neurological symptoms.

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Cerebral DCS

A type of DCS that affects the brain, leading to symptoms such as hemiplegia (paralysis of one side of the body), visual disturbances, confusion, and speech disorders.

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Spinal DCS

A type of DCS that affects the spinal cord, resulting in symptoms like weakness, paralysis, loss of sensation, and incontinence.

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Cardiac DCS

A type of DCS that occurs when microbubbles enter the heart muscle, potentially causing damage to the heart tissue.

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Nitrogen Narcosis

A condition that occurs when the pressure of nitrogen dissolved in the bloodstream during deep dives affects the nervous system, similar to the effects of alcohol.

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High Pressure Nervous Syndrome (HPNS)

A condition that occurs at great depth, mainly due to the high pressure of inert gases, causing neurological symptoms like tremors, confusion, and hallucinations.

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Spirometry

A medical test used to assess respiratory fitness for diving, measuring the volume of air a person can forcefully exhale in one second (FEV1) and the total volume of air that can be exhaled (FVC).

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FEV1/FVC Ratio

The ratio of FEV1 (forced expiratory volume in one second) to FVC (forced vital capacity), used to assess respiratory function and diagnose respiratory conditions like asthma.

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Sinus Problem

A condition that occurs when a diver fails to equalize air pressure in the sinuses, leading to discomfort and pain in the sinuses.

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Ear Problem

A condition that occurs when a diver fails to equalize pressure in the middle ear, causing discomfort or pain in the ear.

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Study Notes

Diving Physiology - Phases and Risks

  • Phase 1: Compression (Descent): Pressure increases with depth (1 atm every 10m). Gases (primarily nitrogen) dissolve into blood and tissues. This is more significant in fat tissue. While this doesn't cause immediate problems, it can lead to decompression sickness if not managed properly during ascent. Body cavities (lungs, sinuses) compress as air volume decreases. Equalizing pressure (e.g., clearing ears) is critical.

  • Phase 2: Isopression: Depth remains constant. No significant physiological changes occur, as long as the diver is stable.

  • Phase 3: Decompression (Ascent): Pressure decreases as the diver returns to the surface. A gradual ascent (no faster than 10m per minute) allows dissolved gases to safely leave the body via exhalation. A rapid ascent leads to rapid gas release, forming bubbles, which can cause decompression sickness. Body cavities expand due to lower pressure. Barotrauma (pressure-related injury) is possible if expansion is rapid (e.g., lung overexpansion).

Diving Risks - Decompression Sickness (DCS)

  • What is DCS? Injury from rapid pressure decrease, often during ascent from deep dives. Symptoms can appear within 10 minutes or be delayed by several days.

  • Mechanism of DCS:

    • On-gassing (saturation): Nitrogen dissolves into tissues from alveoli, blood. Factors influencing saturation include depth, duration, tissue perfusion (blood flow), and fat tissue absorption (nitrogen more soluble in fat).
    • Off-gassing (desaturation): Tissues release nitrogen back into the blood, heading to the alveoli. Pressure in tissues and blood is greater than in lungs; thus, a slow ascent allows nitrogen to leave gradually. A rapid ascent causes supersaturation, where nitrogen comes out of solution too quickly, creating bubbles in tissues and blood.
  • Symptoms:

    • Type 1 DCS: Fatigue, joint/muscle pain, skin rashes.
    • Type 2 DCS: Impaired thinking, numbness, weakness, paralysis, rash, poor balance (neurological, respiratory, cardiovascular symptoms).
  • Treatment: Recompression therapy increases pressure to shrink bubbles, allowing them to dissolve. Patients breathe 100% oxygen to speed up nitrogen elimination. Pressure is then gradually decreased simulating a safe ascent.

Diving Risks - Other

  • Nitrogen Narcosis: Increased nitrogen pressure at depths >30m impairs nerve function. Symptoms mimic alcohol effects (memory loss, confusion, hallucinations). Treatment is ascent to shallower depths. Helium is used in breathing mixes to avoid narcosis at these depths.

  • High Pressure Nervous Syndrome (HPNS): Response to high pressure and rapid changes in pressure at great depths. Symptoms include dizziness, nausea, fatigue. Prevention includes slow/gradual compression, avoiding rapid changes. Small amounts of nitrogen are added to breathing mixes for stabilization.

  • Oxygen Toxicity: Breathing oxygen at high pressures affects the CNS and lungs. Symptoms include seizures and respiratory distress. Prevention includes monitoring oxygen levels and exposure time, avoiding extended high-pressure oxygen exposure.

Diving Safety and Fitness

  • Entry Precautions: Enter water feet-first, avoid diving into shallow water, ensure physical and mental fitness.

  • Diving Buddy System: Essential for support and help.

  • Training and Equipment Check: Professional training and adequate equipment are crucial.

  • Dive Planning: Essential for safety.

  • Pre-Dive Assessment: Medical conditions, such as respiratory problems, ear surgery, diabetes, or mental instability, may prevent diving. Spirometry evaluation (FEV1, FVC, PEF) measures respiratory health. Values must be above 80% for FEV1 and PEF. FEV1/FVC should be above 70%. Avoid alcohol.

  • CAGE (Cerebral Arterial Gas Embolism): Bubble formation within arteries, primarily from pulmonary barotrauma (lung overexpansion during ascent). Symptoms appear rapidly (minutes), with altered mental status, and potential neurological deficits.

  • Neurological DCS types: Cerebral and Spinal DCS involve microbubble occlusion of cerebral or spinal vascular beds. Symptoms include hemiplegia, visual disturbances, confusion, speech disorders, weakness, paralysis.

  • Cardiac DCS: Microbubbles in heart muscle in affected cases. This is sometimes classified as Type 1 DCS.

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