Dive Physiology and Dive Accident Management PDF

D I V E P H YS I O L O GY & D I V E A C C I D E N T MA NAGEMENT DIVING PHYSIOLOGY INTRODUCTION AND OBJECTIVES Due to the tremendous pressure changes we encounter when we go underwater, there are tremendous effects on our bodies. We must understand how these pressure ch...

D I V E P H YS I O L O GY & D I V E A C C I D E N T MA NAGEMENT DIVING PHYSIOLOGY INTRODUCTION AND OBJECTIVES Due to the tremendous pressure changes we encounter when we go underwater, there are tremendous effects on our bodies. We must understand how these pressure changes affect us so we can avoid injury or worse. By the end of this part, you will be able to demonstrate a thorough knowledge of the primary and secondary effects of pressure on the human body DIRECT EFFECT OF PRESSURE (BAROTRAUMA) Our bodies are made up of mostly Non-compressible liquid filled spaces which are unaffected by pressure changes as we ascend or descend into the water. But also, our body contain certain air spaces which do need to equalize with the surrounding water pressure as we descend (or ascend) When we go diving, these air spaces normally will equalize but there are times they won’t. Following are summaries of the various air spaces that could affect a diver.  SQUEEZES DEFINITION A squeeze is defined as a pain due to pressure and occur in any of the body’s air spaces. According to Boyle’s law, as we descend, the air in these spaces will be compressed (squeezed) and if the air pressure on the inside doesn’t equalizewith the water pressure on the outside, then pain will result. Some of these air spaces and their associated squeeze are as follows : LUNG SQUEEZE Our two largest and most delicate air spaces are our lungs. For a breath hold diver, they loose volume as the diver descends until the diaphragm (a large muscle below the lungs) stretches towards the lungs until pain is felt. Scuba and surface supply divers don’t normally get lung squeeze because they are breathing air ambient pressure. Lung squeeze occurs only to breath hold divers T R E AT M E N T F O R L U N G S Q U E E Z E By descending on a single breath, increasing water pressure keeps reducing the volume of the air in the diver’s lungs until the lungs reach their smallest normal size. Ascend to shallower depth if discomfort or pain is felt After this point further volume reduction causes pain from the stretching of the diaphragm and related tissues SINUS SQUEEZE Our head contains 4 sets of sinus passages, which are air spaces. If these passages are congested we may feel pain upon descend Type of pain will vary, depending on which sinus is affected S I N U S S Q U E E Z E FA C T S : Caused by cold or nasal congestion. Can be prevented; don’t dive with a cold or use a decongestant that does not cause drowsiness (like : SUDAFED) Avoid nasal spray as they are not effective. SINUS BLOWOUT Is a condition where blood vessel ruptures in the sinuses due to inability to equalize. Upon coming to the surface there may be a little blood in the nose pocket of the mask. This condition is not serious but the diver should avoid diving for a day or two Similar situation to nose bleed caused sudden rise in elevation (eg: ascent in an elevator). Reason for the term “nose bleed Seats” for the highest seats in the stadium. The best medical advice is not to dive if you have a cold or congestion. Lung or chest congestion can greatly increase your chances of Arterial Gas Embolism as well as sinus squeezes.  EAR SQUEEZE Our ears are very sensitive to pressure changes. The middle ear is an air space that must equalize with the outer ear to avoid pain. We can pass air up the middle ear via the Eustachian tube to equalize the pressure.  Ear squeeze occurs upon descent when middle ear does not equalize with the surrounding increase in water pressure. Eustachian tubes connect the middle ear to the back of the throat so we can equalize the pressure by blowing air into the middle ear. E Q U A L I Z AT I O N T E C H N I Q U E S Vasalva maneuver (pinch nose and blow). Wiggle jaw or yawn. Equalize early and often. Do not wear earplugs. Upon ascent, the ears equalize naturally. REVERSE BLOCK Reverse block is a condition were one ear does not equalize upon ascent. VERTIGO Vertigo is a dizzy or spinning feeling that may Pain and vertigo may occur. occur when both ears don’t equalize at the The only thing the diver can do is to stop the same time or from a reverse block or from a ascent and wait for the ear to equalize ruptured ear drum. Vertigo usually stems from naturally. disturbance to the semi-circular canals Vertigo usually lasts for only a minute or RUPTURE EAR DRUM so. A diver suffering from vertigo should In the event that a diver ruptures an hold on a stationary object until it stops. eardrum, the diver should see a doctor as son as possible for diagnosis. Vertigo can lead to nausea and Generally, eardrums heal whithin 2 vomiting. weeks but hearing will degrade due to scar tissue growing over the ear. TOOTH SQUEEZE Tooth squeeze is rare, but could occur if there is air trapped under a filling or a temporary plug installed during a root canal procedure. Increasing ambient pressure acts on the air space and then the air space acts on the tooth’s nerve. The only action the diver can take is to abort the dive and have a dentist repack the tooth. If pain is associated in the upper teeth, it is more likely to be due to a sins squeeze. INTESTINAL SQUEEZE Not a major problem but may occur when the diver consumes gas causing food and beverages. Upon descent there is no problem as bubbles are compressed. Upon ascent, expanding bubbles may be trapped. In a fullness or mild intestinal pain affects the diver, he should stop his ascent and wait for the gas to pass.  M A N - M A D E A I R S PA C E MASK SQUEEZE The air space created by our mask is affected by the increase in ambient pressure. Air can be added to the mask by exhaling through the nose during descent to make up for the loss of volume. Failure to equalize the mask can result burst blood vessel in the skin and whites of eyes. In the event of a major mask squeeze, the diver should see a doctor. SUIT SQUEEZE Drysuit use a layer of trapped air for thermal protection. As the diver descends and the ambient pressure increases the air trapped inside the suit will loose volume. This will continue until the diver feels a pain due to tightening of the suit material on his/her body. The diver can equalize this air space by adding air from the tank by a suit inflator whip. Suit squeeze is not usually serious and results in zebra stripe bruising.  LUNG OVER PRESSURE INJURIES Lung over pressure injuries are the opposite of squeezes and are caused when a diver holds their breath and then ascends. When breathing on Scuba or any compressed air, the volume of our spaces is maintained upon descent. According to Boyle’s law, this air will expand as we ascend. We risk over-inflation injuries if we do not release the extra volume created as we return to the surface. These injuries occur when the diver ascends too fast or breath holds while ascending.  LUNG OVER PRESSURE INJURIES The air expands in the lungs and can rupture the alveoli (thin air sacks in the lungs) and then air enters areas of the body where it can be very dangerous. LUNG OVER PRESSURE INJURIES ARE THE LEADING CAUSE OF DIVING F ATA L I T I E S S O E V E R Y E F F O R T M U S T B E TA K E N T O A D D R E S S T H E C A U S E S. CAUSES OF LUNG OVER PRESSURE INJURIES ARE THE SAME FOR ALL THE TYPES AND INCLUDE : B R E AT H H O L D I N G U P O N A S C E N T. RAPID, OR UNCONTROLLED ASCENT (BLOW-UP) COUGHING UPON ASCENT H E AV Y L I F T I N G PA N I C K E D A S C E N T LUNG CONGESTION The lungs have over 30 millions Alveoli and are litterally an Air Sponge. Alveoli walls are only 1 or 2 cells thick and can only withstand a 2 psi difference with ambient pressure before they rupture. Where in the lungs the alveoli rupture will depend on where they are the weakest. DEPENDING ON WHERE IN THE LUNGS THE RUPTURE OCCURS, IT CAN C R E AT E O N E O R A C O M B I N AT I O N O F T H E F O L L O W I N G P R O B L E M S : S U B C U TA N E O U S E M P H Y S E M A. MEDIASTINAL EMPHYSEMA. PNEUMOTHORAX. ARTERIAL GAS EMBOLISM (A.G.E) S U B C U TA N E O U S E M P H Y S E M A With Subcutaneous Emphysema, alveoli rupture and air escapes the chest cavity and air bubbles collect under the skin usually in the upper chest and neck area. SIGNS/SYMPTOMS : T R E AT M E N T : Swelling in neck, upper shoulders or chest. Any necessary first aid (A.B.C). Oxygen. Change in voice. Treat for shock. Breathing difficulty (Dyspnea). Patient can assume his most comfortable position, but must be at Difficulty swallowing. rest. Crepitious (Crackly or crunchy sound when touched). Evacuation to a medical facility. MEDIASTINAL EMPHYSEMA With Mediastinal Emphysema, alveoli rupture near the center of the chest and air bubbles collect over or around the heart putting pressure on the heart muscle. SIGNS/SYMPTOMS : T R E AT M E N T : Chest pain. (Heart attack like). Any necessary first aid (A.B.C). Pain under the breastbone.. Oxygen. Breathing difficulty (Dyspnea - shortness of breath). Treat for shock. Cyanosis (blue coloured lips and skin). Sitting, curled up will be the best position for ease of breathing. Denial. Evacuation to a medical facility. PNEUMOTHORAX Alveoli rupture and air is trapped between the lung and chest wall (pleural lining) collapsing the lung. SIGNS/SYMPTOMS : T R E AT M E N T : Swelling in neck, upper shoulders or chest. Any necessary first aid (A.B.C). Oxygen. Change in voice. Treat for shock. Breathing difficulty (Dyspnea). Patient can assume his most comfortable position, but must be at Difficulty swallowing. rest. Crepitious (Crackly or crunchy sound when touched). Evacuation to a medical facility. ARTERIAL GAS EMBOLISM (A.G.E.) AGE is the most serious of the lung over pressure injuries. Alveoli rupture and air enters the blood stream, travelling through the carotid arteries up to the brain, causing a blockage of blood flow. The brain requires a constant blood and this blockage causes brain cells distress. SIGNS/SYMPTOMS : T R E AT M E N T : CNS symptoms, similar to stroke. Rapid onset (within 5 min. of ascent). First Aid (C.P.R. Or A.R.) Coughing up a bloody red sputum. Numbness, tingling, paralysis. Oxygen. Confusion, loss of memory. Treat for shock. Staggering, vertigo, loss of balance. On back and monitor or recovery position (3/4 prone). Weakness, loss of motor control. Immediate transport to a recompression chamber. Unconsciousness, death. PREVENTION FOR LUNG OVER-PRESSURE INJURIES : A L W AY S B R E AT H E N O R M A L LY, N E V E R H O L D Y O U R B R E AT H. A V O I D R A P I D A S C E N T. M A N A G E Y O U R S T R E S S L E V E L T O M I N I M I Z E P O T E N T I A L PA N I C. N E V E R L I F T H E A V Y O B J E C T S U N D E R W AT E R. DO NOT DIVE IF CHEST CONGESTED (CHEST COLD, BRONCHITIS,ETC.) N E V E R S W I M U P W I T H H E AV Y O B J E C T S. M A I N TA I N Y O U R É Q U I P E M E N T S , E S P E C I A L LY B C D A N D D R Y S U I T I N F L AT O R LUNG OVER PRESSURE SUMMARY  INDIRECT EFFECT OF PRESSURE The following are indirect effects of breathing air under pressure. These problems are like side effects in that they affect the brain and body in an indirect way. In the indirect effects of pressure we will find : CNS Oxygen toxicity. Nitrogen Narcosis. Decompression Sikness (type I and type II). Decompression stress (can be asymptomatic). CNS OXYGEN TOXICITY CNS (Central Nervous System) Oxigen Toxicity occurs when the brain is exposed to too high of a partial pressure of oxygen. The high partial pressure of oxygen forms super oxide compounds in the brain affect the function of neurons (brain cells). SIGNS/SYMPTOMS : T R E AT M E N T : Get the diver to the surface and begin CNS toxicity symptoms are referred to dive accident management - Lower as VENTID or ConVENTID ppO2. Visual disturbances. PREVENTION : Ears - ringing. Never dive deeper than 200 few with air. Nausea. Twitching or tingling. Never use 100% Oxygen for diving. Irritability. Work out Maximum Operating Depth (MOD) if using Nitrox. Dizziness Know what gas is in your breathing tank (Analysis and Labeling). Convulsions. CNS toxicity leads to convulsions, which are usually fatal underwater.  Also known as “Short Term Oxigen Toxicity” due to its rapid Although this is a problem of concern onset (0 to 30 minutes). to mixed gas and bell/saturation divers, Occurs only when the diver is under water or in a it can affect divers who use air on deep recompression chamber. dives or use NITROX (Oxygen Enriched Air). Nitrox divers must calculate MOD Occurs when exposed to partial pressures of oxygen greater for the Nitrox mix they breathing. than 1.6atm (220 fsw on air, 115 fsw on Nitrox 36%, 18 fsw on pure Oxygen). If symptoms are noticed, the diver must immediately switch to a breathing gas Causes : with less oxygen or convulsions will begin. Conditions where the partial pressure of oxygen is too high : Using pure Oxygen as a breathing gas. If interested in getting a better and more technical understanding on Oxygen toxicity you can watch Using Nitrox at greater deeper than its Maximum those videos (one is about CNS Oxygen Toxicity and the second one is about Pulmonary Oxygen Toxicity) : Operating Depth (MOD). https://youtu.be/qzUy672I4fU?si=KCnSTgNkA28rMxu0 Using air deeper than 220 fsw (66 msw). https://youtu.be/wVTQhQc8g1k?si=jI6LaY-ZBM5igSD2 NITROGEN NARCOSIS Although inert, Nitrogen is an anesthetic gas under pressure. Higher than normal partial pressure of nitrogen disrupt brain cell signals in a manner similar to alcohol intoxication. The partial pressure of Nitrogen reaches this level (when breathing air) at about 100 fsw and deeper. Problems occur when the diver loses track of air, depth, time and decompression limits. SIGNS/SYMPTOMS : T R E AT M E N T : Symptoms dissipate upon ascent to shallower depth. Foolish behaviour, loss of judgement. Replacing Nitrogen with Helium for deep diving eliminate the narcosis effect. Euphoria, feeling of well-being. PREVENTION : Anxiety or fear. Don’t dive deep. Confusion or loss of motor coordination. Build up experience to allow you to focus on the job. Ascend if symptoms are interfering with work. Loss of memory. NITROGEN NARCOSIS IS A SERIOUS PROBLEM AND SHOULD NOT BE T O Y E D W I T H. D I V E R S A L W AY S N E E D T H E I R W I T S A B O U T T H E M , E S P E C I A L LY AT D E E P E R D E P T H S. M A N Y D I V E R S H A V E D I E D B Y T R Y I N G TO GO DEEP GET “NARC’ED” DECOMPRESSION SICKNESS Decompression Stress : When we ascend from a dive, tiny micro- bubbles form in our tissues and blood. Our Decompression sickness is a man-made sisease bodies can tolerate a certain amount of these that can happen anytime we are exposed to micro-bubbles but it does stress our bodies. If breathing compressed air under pressure. The we can get an excessive amount of these bubbles we can get decompression sickness. nitrogen air is an inert gas that dissolves out when The actual mechanism of decompression the diver ascends. As the nitrogen comes out of sickness is still unknown but what is know is our tissues it forms micro-bubbles that either get that the more bubbles that form (and depending on where that form) the more trapped in tissues or form in our blood stream and serious the decompression stress will be. create problems in our bodies. Possible decompression sickness mechanism : Bubble collection in blood vessels Absorption of inert gas : impairing blood flow. Inert gas (Nitrogen) in the breathing mixture is absorbed by Sludging of blood due to platelet conglomeration. tissues in accordance with Henry’s Law. Mechanical pressure from bubbles Upon ascent, these gases come out of solution and they pressing on nerve tissues. must be released at safe rate to minimize decompression Chemical reactions within the blood. stress. H E N R Y’ S L A W  U.S. Navy Tables DCIEM Micro DCS Type I DCS Type II No Death DCS Bubbles Pain Only Serious Asymptomatic DCS DECOMPRESSION SICKNESS TYPE I Also known as “Pain Only” decompression sickness. Occur when enough bubbles from within our tissues to cause noticeable symptoms. Considered to be bubble formation in tissues and putting pressure on the nerve ending in those tissues. SIGNS/SYMPTOMS : T R E AT M E N T : Follow first aid protocols. Pain in joints, Administer Oxygen. Pain in Muscles. Treat for shock. Niggles ( a transient pain). Rehydrate with Isotonic solution (slightly Salty). Red itchy rash (skin Bends). Contact a Diving Doctor. Transport to a recompression Chamber (No Rush) DO NOT give Pain medication (Aspirin or Tylenol). DECOMPRESSION SICKNESS TYPE II Also known as “CNS DCS” or “Serious DCS”. Type II DCS occurs when an excessive amount of bubbles from in the blood and block blood flow to the brain or form in the spinal fluid or fluid in the inner ear. The symptoms are Central Nervous System (CNS) related and this type of decompression sickness is life threatening. SIGNS/SYMPTOMS : (SLOW ONSET >5MIN TO 24H) T R E AT M E N T : Numbness, tingling, weakness, paralysis. Follow first aid protocols. Loss of memory, confusion, loss of senses. Administer Oxygen. Staggering, loss of coordination, loss of motor control. Treat for shock. Rehydrate with Isotonic solution (slightly Salty). Fatigue, abdominal cramps. Contact a Diving Doctor. Any CNS or stroke-like symptoms. Transport to a recompression Chamber (No Rush) Unconscious, death. DO NOT give Pain medication (Aspirin or Tylenol).  First Aid Serious Manifestations Presentation ABCs Cerebral symptoms Position of the Diver (supine or Onset usually at dive site. Spinal cord symptoms Recovery) Referred early by means of Cardiopulmonary symptoms Administrate O2 diving Hotline or Emergency Cardiovascular symptoms Fluid administration services. Inner ear symptoms Keep Diver on supine position Refer for Recompression if suspected A.G.E. Urgent evacuation by emergency services Consider Treatment without Recompression YES NO Recompression Oxygen and fluids. Consider NSAIDs Are the logistics of evacuation Y difficult, dangerous or impractical ? E Mild Manifestations Presentation NO S First Aid Onset often later, symptoms Musculoskeletal pain. Serious symptoms on local often ignored or concealed Consider oxygen if Cutaneous symptoms. evaluation ? early. presentation is on the day of Constitutional symptoms. Often self-referred, possibly diving. Not urgent if later Lymphatic symptoms. days after onset. DIVECO MARINE DIVE ACCIDENT MANAGEMENT