AHF 2203 AVIATION HUMAN FACTORS Hyperventilation and Cabin Pressurization

Presentation Outline Part 1: Hyperventilation Part 2: Cabin Pressurization

Learning Outcomes At the end of this session, student should be able to: Identify and aware of Hyperventilation syndromes and their causes, effects, preventions and medical cure needed especially during flight. Understand why aircraft cabin need to be pressurized especially at higher altitude.

Part 1: Hyperventilation

What gases do you consume during breathing? How do you breathing? Why do you breathing? What gases do you consume during breathing? What happen if you are stopped breathing? Which one comfortable for you: Slow breathing? Rapid breathing?

What is Breathing???

Cont. Breathing: Process of taking air (O2)into the lung and exchanging gas (CO2)to the environment. CO2 is the gas produce by all living things as a WASTE PRODUCT.

Cont. It is important for maintaining chemical balance in the body and control our breathing. Access CO2 is eliminated by the lung during isolation (separation). However, some amount of CO2 must remain in the body – to maintain chemical balance in the body.

Cont. The concentration of gases in the body controlled by BRAIN. Average adult breathing cycle: 12-16 breath per minute. Rate of breathing can be rapid/slow down.

Cont. What happen to your breathing (slow/fast) when your get into emotional problem (angry/stress/anxiety/panic)??

Hyperventilation Hyperventilation (overbreathing) can be defineed as excessive rate and depth of respiration leading to abnormal loss of CO2 from the blood. It causes the excessive loss of CO2 from the blood. This results to degrade the chemical balance in the blood

Cont. The brain will react by restricting the blood flow. By this restriction, the blood flow to the brain cause (result of Hyperventilation): Poor judgment Impaired memory Performance impairment Late of reaction time Muscle coordination.

Cont. If this chemical imbalance continue (not quickly cured) it might result: UNCONCIOUSNESS!!! With the breath held the carbon dioxide levels build up once more and the symptoms disappear in reverse order.

Hyperventilation Process Increase in rate and depth of breathing Excessive loss of CO2 Chemical Imbalance Brain restrict the blood flow (if chemical imbalance continue) Unconsciousness Imagine if the unconsciousness happens to the PILOT??

Cont. Hyperventilation rarely painful. Many symptoms and sign are similar to hypoxia. So this is the difficulty to recognize Hyperventilation.

Difference between Hypoxia and Hyperventilation Skin may look pale. As we ascend, it can occur slowly and gradually over time. Muscle activity might becomes spastic Skin may look blue (cyanosis). Can occur rapidly. Muscle soft and limp with little or no activity.

Cont. To help differentiate between Hyperventilation and Hypoxia please monitor this element: Flight attitude Cabin altitude (if pressurized) Oxygen system (if in use) Emotional state Awareness of your current flight environment.

Cont. Hyperventilation and Hypoxia can occur simultaneously. This making it difficult to diagnose (analyze) the problem.

Relation between Hypoxia and Hyperventilation Hypoxia: lack of oxygen in blood Body attempt to circulate more oxygen. Increase heart and respiratory rate Tend to breath rapidly caused Hyperventilation

Causes of Hyperventilation Main cause of Hyperventilation is EMOTIONAL PROBLEM What is emotional problem? Please give the example of emotional problem?

Cont. Emotional Problem Anxiety Fear Anger Panic Stress

Cont. Other causes of Hyperventilation that not caused by emotional problem: Pain Bleeding Cardiac disease, such as congestive heart failure (abnormal collection of blood) or heart attack Drugs (such as an aspirin overdose) Respiratory disease: Infection such as pneumonia (infection of one or both lungs which is usually caused by bacteria, viruses, or fungi) or sepsis (toxins in the blood or tissues) Lung disease such as asthma, Pregnancy

Symptoms of Hyperventilation Dizziness Lightheadedness Blurred Vision Numbness Tingling Hot and cold sensations. Muscle incoordination (cramps). Shortness of breath Unconsciousness *These symptoms also can be symptoms of Hypoxia * If you have hyperventilation syndrome, you might not be aware you are breathing fast. You might be aware of those symptoms above.

Prevention of Hyperventilation Monitor your rate and depth of breathing. Learn to recognize stressors that would cause you to over breath. Avoid panic.

Treatment of Hyperventilation FAA Checklist (usually when occur simultaneously with hypoxia): Wear Oxygen Mask Check the oxygen regulator is turned on Check all connection are secure Slow down your breathing rate and depth Descend to suitable altitude (10000 ft and below)

Cont. Other treatment: Best method is to voluntarily reduce rate of breathing (Normal rate is 12-16 breaths per minute) Go to 100% O2 (if available) Talk or sing (to increase CO2 level) Breathing into a bag.

Part 2: Cabin Pressurization

Cont. Pressure is decrease when altitude is increase. Outside pressure (atmospheric pressure) could be harmful in the high altitude to human body. So to maintain pressurization in the cabin at high altitude is important.

1926: Ford Tri-motor First all-metal aircraft designed for passengers

1926: Ford’s Tri- motor ‘Ford Trimotor’ also called as the “Tin Goose”. Can carried 12/13 passengers and could fly up 6,000 feet (1,829 kilometre), but it’s climb to that altitude was slow, level off, bump around, and drop repeatedly before it reached its cruising altitude. With no air conditioning and little heating, the plane was hot in summer and cold in winter, With no circulation system, its environment was made even more unpleasant by the smell of hot oil and metal, leather seats, and disinfectant used to clean up after airsick passengers. Opening a window was the only way to escape the smell.

What is Cabin Pressurization? Cont. What is Cabin Pressurization? Cabin pressurization is the active pumping of compressed air into an aircraft cabin . The purpose of these systems is to provide a safe and comfortable cabin environment, and to protect all cabin occupants from the physiological risks of high altitudes (e.g. hypoxia, decompression sickness).

Cont. It involves simultaneous control on: Temperature Humidity Air Circulation Cabin Pressure Pressurization is essential above 10,000 feet

Cont. Most pressurize aircraft today cruise at altitude of 25000 ft - 51000 ft while keeping cabin at comfortable pressurize altitude as in 6500 ft - 8000 ft.

How Cabin Pressurization Works??

Basic Mechanic of Cabin Pressurization System

Cont. Outside air continuously enters engine. Air is compressed by the compressor in the engine and then passes through cooling packs. Cool outside air goes into mixing chamber and mixed with re-circulated air from the tanks. Air from mixing chamber then continuously supplied to the cabin. Outflow valve then control the air flow by open and close the valve to maintain the suitable pressure.

Cont. Outflow Valve

Advantage of Pressurized Flight Oxygen mask no need to be worn Risk of decompression sickness minimized Decompression sickness caused by nitrogen forming as bubbles in the blood Less noise and vibration during flight. Better control of temperature and air ventilation (system supply fresh air) . Fewer trapped gas problem. The gas can’t be released especially by our body cavities part.

Disadvantages of Pressurized flight Always a chance of DECOMPRESSION.

What is Decompression?? Cont. Decompression means aircraft loss of cabin pressurization. It can occur because cabin pressurization system not functioning well, the damage to the aircraft that causes a break in the aircraft structure which enabling cabin air to escape outside the aircraft

Cont. THREE major types of decompression: Slow Decompression Rapid Decompression Explosive Decompression Vary with TIME!

Slow Decompression Cont. When the cabin loss pressure greater than 10 seconds. It happens in case of a small air leak. Potential to be most dangerous types of decompression when unaware cabin altitude is going up (since it happen very slow).

Rapid Decompression Cont. Total loss of cabin pressurization within 1-10 seconds. It happens in case of big air leak.

Explosive Decompression Cont. Explosive Decompression When cabin pressurization loss in less than 1 second!!! This rapid change can occur faster than our lungs can decompress. Lung damage possible to occur. It happens in case of big air leak.

Qantas Flight Decompression, Big Hole in the Fuselage Cont. Qantas Flight Decompression, Big Hole in the Fuselage

Factors Affecting Severity and Times of Decompression Size of cabin the larger the cabin, the longer the decompression time (slower decompression) Size of the opening (air leak) the larger the opening, the faster the decompression time.

Cont. Differential ratio Flight altitude the greater the pressure differential between the cabin pressure and the external environmental pressure, the more forceful the decompression. Flight altitude higher altitudes create greater threats for physiological consequences (see *Time of useful Consciousness (TUC)) *TUC also known as Effective Performance Time (EPT).

Times of Useful Consciousness Cont. Times of Useful Consciousness TUC or EPT is the period of time that a pilot has from the time oxygen become less available until the time when he or she loses the ability to recognize and take action If someone goes beyond TUC, then he or she isn’t even aware of the problem and will not take corrective action The keyword is EFFECTIVE or USEFUL (He or she might be conscious but not making expected useful or effective decision). TUC decrease as altitude increases.

Cont. Altitude Conscious time 20000 5 – 12 minutes 25000 2 – 3 minutes 30000 45 – 75 seconds 35000 30 – 60 seconds 40000 10 – 30 seconds 45000 12 – 15 seconds 50000+ 12 or less seconds

Effects of Decompression Physical effects : Noise: Noise from decompression can increasing to very loud explosive sound. Communication can be disturbed. Fog: Form when decreasing in temperature and pressure associated with decompression Effect visual problem Flying Debris (dust/dirt) Dust and dirt cause visual problem. Cooler Temperature Pressure or air departs the cabin Hypothermia (abnormal body temperature) can occur.

Cont. Physiological effect: Trapped Gas Decompression sickness The gas can’t be released especially by our body cavities (hole) part (e.g. middle ear, teeth etc.) Certain gases that will expand with decreasing in pressure Decompression sickness Occur due to nitrogen in the body coming out as solution and forming bubble. Hypothermia Cause by cooler temperature at high altitude

Cont. Hypoxia Hyperventilation Caused by rapid decreasing in partial pressure of oxygen Lead to deficiency of oxygen in blood Hyperventilation The emergency could increase rate and depth of breathing causing hyperventilation.

Oxygen Systems Portable Oxygen Cylinders Oxygen cylinders are located throughout the cabin. The number and location of the oxygen cylinders varies, depending on the aircraft cabin configuration.

Conclusion Hyperventilation: rapid rate of respiration that may lead to the excessive loss of carbon dioxide from the lung. Cabin pressurization is a convenience mean in control the some of the hazard for human body in high altitude flight.

5 Minutes for Q/A session End of Presentation #5 5 Minutes for Q/A session