AHF 2203 AVIATION HUMAN FACTORS Presentation 6: Decompression Sickness and Trapped Gas 1Presented by Mohd Amirul for AMC

Recapitulate Lets recap what we have done last session: – Definition of Hyperventilation – Hyperventilation process – Causes of Hyperventilation – Symptoms of Hyperventilation – Preventions of Hyperventilation – Treatments of Hyperventilation – What is Cabin Pressurization? – Purpose of Cabin Pressurization – How Cabin Pressurization Works? – Advantage of Pressurized Flight – Definition of Decompression – Types of Decompression – Factors affecting Decompression’s time and severity. – Effects of Decompression. 2Presented by Mohd Amirul for AMC

Presentation Outline Part 1: Decompression Sickness Part 2: Trapped Gas 3Presented by Mohd Amirul for AMC

Learning Outcomes At the end of this session, student should be able to: – Relate gas law to trapped gas and decompression sickness syndromes. – Recognize the causes, symptoms, treatment, and prevention steps of decompression sickness. – Recognize the difficulties of affected body area occur by trapped gas during ascent and descent. – Identify causes, symptoms, treatment, and prevention steps of each trapped gas affected body areas 4Presented by Mohd Amirul for AMC

Part 1: Decompression Sickness (DCS) Presented by Mohd Amirul for AMC5

The amount of gas in solution is proportional to the pressure of that gas over the solution As the pressure of the gas above a solution increases, the amount of that gas dissolved in the solution increases Reverse is also true, as the pressure of the gas above a solution decreases, the amount of gas dissolved in the solution decreases and forms a “bubble” of gas within the solution Cont. Henry’s Law 6Presented by Mohd Amirul for AMC

Henry’s Law Illustration Low pressure equilibrium Low concentration Double the pressure equilibrium Double the concentration 7Presented by Mohd Amirul for AMC

Nitrogen dissolved in the blood responds in same way. Carbonated drink: Once the seal is opened, You will hear the gas that has been under pressure escaping and see the bubble are forming. The bubbles are CO2 gas coming out of the solution as a result of sudden exposure to lower barometric pressure (atmospheric pressure). Cont. Example: 8Presented by Mohd Amirul for AMC

It ambiguous to human body: – The body stores nitrogen in tissue and the fluid. – When body exposed to DECREASE barometric pressure or rapid decompression, nitrogen dissolve on the body come out as solution. – If nitrogen leave solution faster than the body can compensate to respiratory or circulatory systems, the nitrogen bubble will form and enlarge at different area of the bodies. – This can cause variety of symptoms/sign: DECOMPRESSION SICKNESS. Presented by Mohd Amirul for AMC9 Cont.

Decompression Sickness (DCS) Exposure to change in barometric pressure can cause inert gasses mainly nitrogen to come out as solution and form the bubbles. Decompression sickness is caused by nitrogen forming as bubbles in the blood. As pressure decreases, gases (nitrogen) dissolved in body fluids are released as bubbles. 10Presented by Mohd Amirul for AMC

Can occur in the blood, other fluids, or in the tissues This is related to the inefficient removal and transport of the expanded nitrogen gas volume from the tissues to the lungs. Presented by Mohd Amirul for AMC11 Cont.

Types of DCS FOUR types of DCS: Type I (Non-Serious) – Bends – Skin Manifestations Type II (Serious) – Chokes – Neurological Manisfestations Presented by Mohd Amirul for AMC12

The Bends Bend: Pain in the large joints (e.g. knee, elbow etc) Common type of DCS in aviation. Pain from mild to unbearable. If one experience may occur in other location during subsequent (following in time or order) exposure. (If reappearing at ground level during descent, can be serious condition if left untreated) Presented by Mohd Amirul for AMC13 Cont.

Skin Manifestation * manifestation: clear appearance/indication Symptoms: Tingling, itching, cold/warm sensation. Cause by form of bubble localize under the skin. – Red spot pattern appear under the skin – Usually around shoulder and upper chest. Continued exposure may lead to more serious forms of decompression sickness Presented by Mohd Amirul for AMC14 Cont.

The Chokes * Chokes: Breath with great difficulties like the neck being wringed. Related to chest and lung. Bubble intrude in pulmonary vessel (blood vessel in lung). Presented by Mohd Amirul for AMC15 Cont.

Symptoms – Deep and sharp pain or burning sensation under the sternum – Shortness of breath – Feeling of suffocation with decreasing ability to take a breath Might lead to feel of suffocation (poor of oxygen(Hypoxia)) and result of unconsciousness. Presented by Mohd Amirul for AMC16 Cont.

Neurological Manifestation Very serious type of DCS and can result in DEATH. Affect nervous system (brain, spinal cord, other nerves). Symptoms: – Headache – Visual disturbances – Unexplained fatigue – Paralysis Presented by Mohd Amirul for AMC17 Cont.

Factors or Cause affecting DCS Altitude – Less risk below ft MSL – Below 25,000 feet is rare – Above 25,000 feet may occur. Repetitive Exposure – Exposure to altitude above 18,000 ft MSL during short period. Rate of ascent – The faster (short) the rate of ascent, the greater the risk. Presented by Mohd Amirul for AMC18

Time (duration) at altitude – The longer you are at altitude, greater the risk. Age – older, greater the risk. Previous injury – Recent limb/joint injury, greater the risk. Presented by Mohd Amirul for AMC19 Cont.

Ambient temperature – Exposure to very cold temperature increase the risk of DCS Physical Exercise: – Physically active while flying at 18,000 ft or above, greater the risk. Alcohol Consumption: – Greater the risk. Presented by Mohd Amirul for AMC20 Cont.

Scuba Diving before Flying – During scuba diving, he/she requires breathing air under increase atmospheric pressure. – Amount of nitrogen stores under the body increases. – Enough time should be allowed to eliminate excess nitrogen stored in the body. (approximately: 24 hours before fly) – Cases of decompression sickness have occurred in individuals who fly in cabins as low at 5,000 feet Presented by Mohd Amirul for AMC21 Cont.

Treatments of DCS Emergency Treatment – 100% oxygen for everyone onboard – Declare an emergency – Descent as rapidly as possible – Immobilize affected areas – Land as soon as possible – Medical evaluation by a QUALIFIED flight surgeon. – Decompression chamber therapy if required Presented by Mohd Amirul for AMC22

Prevention of DCS Protective measures include: – Cabin pressurization. – Limitation of time at high altitude. 23Presented by Mohd Amirul for AMC

Part 2: Trapped Gas Presented by Mohd Amirul for AMC24

Boyle’s Law State that a volume of gas is inversely proportional to pressure to which is subjected, with the temperature remain constant. E.g.: Balloon taken in certain altitude in altitude chamber. – As Pressure decrease, volume in the balloon will EXPAND – As Pressure increase, volume in the balloon will DECREASE. Presented by Mohd Amirul for AMC25 *Altitude Chamber: used for aerospace/high terrestrial altitude research or training to simulate effects of high altitude of human body.

Illustration of Boyle’s Law Pressure decrease, Volume increase Site level 10,000 feet 18,000 feet 25,000 feet 43,000 feet Cont. 26Presented by Mohd Amirul for AMC

Cont. Boyle’s law application to human body: Presented by Mohd Amirul for AMC27  Gases within the body are influenced by pressure and temperature changes outside the body  Ascent – pressure is decreased and gases expand.  Descent – pressure is increased and gases contract.  The body can withstand changes in total pressure as long as the air pressure within the body cavities is equalized to ambient pressure

Trapped Gas Trapped gas means the gas can’t be released especially by our body cavities part. Occur inside natural cavities in human body that contains various amount of gases. Presented by Mohd Amirul for AMC28

Our body cavities that often experienced trapped gas are: 1.Middle ear 2.Sinuses 3.Teeth 4.Stomach & Intestines (Gastrointestinal tract) Presented by Mohd Amirul for AMC29 Cont.

1. Middle Ear FRONTALS ETHMOIDS SPHENOID MAXILLARY 2. Sinus 4. Stomach and Intestines 3. Teeth Cont. 30Presented by Mohd Amirul for AMC

1. The Middle Ear Presented by Mohd Amirul for AMC31

Anatomy of Ear Cont. 32Presented by Mohd Amirul for AMC

33 The ear is not only an organ of hearing but also one of regulating equilibrium. When ascending to altitude, flight’s occupants often experience physiological discomfort during changes in atmospheric pressure. Ear Cont. Presented by Mohd Amirul for AMC

The Middle Ear Ascent to altitude – As ambient pressure decreases with ascent, gas expands within the middle ear – Air escapes through the Eustachian tubes to equalize pressure – As pressure increases, the eardrum bulges outward until a differential pressure is achieved and a small amount of gas is forced out through eustachian tube and the eardrum relaxes. Cont. 34Presented by Mohd Amirul for AMC

Descent to altitude – Equalization of pressure does not occur automatically – Eustachian tube performs as a flap valve and allows gas to pass outward easily, but resists the reverse. – During descent the ambient pressure increase, the flap valve can stop the returning air into the middle-ear to equalize the pressure. – If pressure is not equalized Ear block may occur and it is extremely difficult to reopen the eustachian tube The eardrum may not vibrate normally and decreased hearing results (minor hearing lost). Cont. 35Presented by Mohd Amirul for AMC

Middle Ear Block Cont. 36Presented by Mohd Amirul for AMC

Symptoms of Middle Ear Block Symptoms – “Ear congestion” (excessive accumulation of blood) – Ringing in the ears. – Inflammation. – *Discomfort. – Pain. – Temporary impairment of hearing – Bleeding (severe cases) – Eardrum rupture 37Presented by Mohd Amirul for AMC

*Middle Ear Discomfort A cold can produce enough congestion around the Eustachian tube to make equalization difficult. This causes and ear block causing a build up in pressure that can be very painful. Severe ear pain and loss of hearing that can last several hours to several days. Can cause rupture of the ear drum Usually occurs on descent 38Presented by Mohd Amirul for AMC

Factors/Cause of Middle Ear Block Presented by Mohd Amirul for AMC39 Contributing Factors – Flying with head cold – Flying with a sore throat

Middle Ear Block Treatment – Yawning or swallowing – Performing “Valsalva” – Nasal sprays – best used prior to descent – Pain medications – For infants / children – provide a bottle / straw to suck – Ascend to safe altitude where symptoms subside and then slowly descend 40Presented by Mohd Amirul for AMC

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Middle Ear Block Prevention Prevention – DO NOT FLY WITH A HEAD COLD 42Presented by Mohd Amirul for AMC

2. Sinus Presented by Mohd Amirul for AMC43

Sinus Sinus is the cavity within a bone, especially in the bones of the face. FRONTALS ETHMOIDS SPHENOID MAXILLARY 44Presented by Mohd Amirul for AMC

The Sinuses Block Most often involves frontal sinuses (above each eyebrow) and maxillary sinuses (both cheeks) Sinus ducts have openings into the nasal passage Gas escaped with increases upon ascent most often without problems With descent, air moves back out through the ducts if they are open If the openings are swollen, a blockage may occur. 45Presented by Mohd Amirul for AMC

Cause of Sinus Blockage Commonly caused by cold (flu) / allergies. Presented by Mohd Amirul for AMC46

Symptoms of Sinus Blockage – Severe pain – Possible referred pain to teeth 47Presented by Mohd Amirul for AMC

Treatment of Sinus Blockage. Presented by Mohd Amirul for AMC48 Treatment – Equalize pressure as quickly as possible – Valsalva is sometimes effective – Ascent to safe altitude then slow descent – Nasal sprays may help

Prevention of Sinus Blockage Never fly with the cold/ sinus problem like allergy or under medication of upper respiratory problem. Presented by Mohd Amirul for AMC49

3. Teeth Presented by Mohd Amirul for AMC50

The Teeth Air trapped within teeth expands with ascent. Rarely occur since we’ve modern dentistry nowadays. Pain often increases with altitude. 51Presented by Mohd Amirul for AMC

Problem includes: – Cavity Air trapped inside tooth and can’t escape. – Abscess Small pocket of trapped gas at the base/root of teeth Rarely occur Dull pain during ascent Presented by Mohd Amirul for AMC52 Cont.

Treatment and Prevention Treatment – Descent – Pain medications Prevention – Good dental hygiene 53Presented by Mohd Amirul for AMC

4. Gastrointestinal Tract Presented by Mohd Amirul for AMC54

Gastrointestinal Tract Gastrointestinal: related to stomach and intestines Most frequently experienced with a rapid ascent (decrease in barometric pressure) Symptoms result from gas expansion Above 25,000 feet distention could be large enough to produce severe pain – May produce interference with breathing 55Presented by Mohd Amirul for AMC

Gastrointestinal System 56Presented by Mohd Amirul for AMC Cont.

57Presented by Mohd Amirul for AMC Cont.

Causes Sources of Gas – Swallowed air (including gum chewing) – Food digestion Food that can cause excess gas formation: – Onions – Broccoli – Cabbage – Pumpkin – Carbonated beverages CO 2 will expand at high altitude. – Drink large amount of water at open air (e.g. water cooler) 58Presented by Mohd Amirul for AMC

Treatment – Walking or moving – Belching (burp) or passing gas – Massage the affected area – Loosen restrictive clothing – Use of a gas reducing agent – Descent to a higher pressure Presented by Mohd Amirul for AMC59

Prevention Avoid consume the food/beverage that can cause access gas formation. Drink from the bottle. Presented by Mohd Amirul for AMC60

Conclusion Decompression Sickness: Occurs when gases (nitrogen) dissolved in body fluids are released as bubbles. Trapped Gas: Expanding gases within the body cannot escape to allow the equalization of body pressures. Presented by Mohd Amirul for AMC61

Key Points Henry’s Law Decompression Sickness Type of DCS Factors or Cause Affecting DCS Treatment of DCS Prevention of DCS Trapped Gas Boyle’s Law Cavities 62Presented by Mohd Amirul for AMC

End of Presentation #6 5 Minutes for Q/A session 63Presented by Mohd Amirul for AMC

Quote of the Day We have TWO choices in life. DO or NOT DO. Both of these will give the consequences in your future. Think about it=) Presented by Mohd Amirul for AMC64