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MMP minimum requirements for MK-21
0 to 60 FSW / 90psig minimum
61 to 130 FSW / 135 psig
131 to 190 FSW / 165 psig
Whose permission is required to use the ships anchor chain or wire as a descent line?
How long is a diver required to remain within 30 minutes of the diving unit after surfacing from a dive?
When is a DMO required on-site for a mixed gas dive?
All dives exceeding normal working limit i.e. 300'/: 30 or exceptional exposure, exceeding working limits of the rig used.
What are the normal and maximum equipment working limits for Mk-21 MOD 1, and Mk-21 MOD 0?
Mk-21 MOD 1 = 300 / 380 FSW
Mk-21 MOD 0 = 950 / 950 FSW.
State the requirements for the Mk-21 HEO2 mixed gas EGS.
EGS mix will be the same as the bottom mix. If bottom mix contains less than 16% 02 the EGS mix may range from 15 to 17% 02.
When analyzing gas, the instrument testing the 02 concentrations must be accurate within how much percent?
HEO2 must be analyzed with an instrument having an accuracy of +/- .5%
Maximum 02 concentrations for gas dives have been selected to ensure the dive does not exceed what PPO2?
1.3 ATA. The 02 may range from 10% to 40% depending on the depth of the dive.
What should be done if the workload is relatively strenuous or the workload is cold?
Select the next longer decompression schedule (time). If a chamber is available and the water is cold, shift to a 'sur-d-02' table but use the next longer schedule (time) for the chamber phase of decompression.
You have a delay between 50' and 30' and you are on a sur-d-02 table that has no water stops?
Add the delay time to the chamber stop.
When may all chamber occupant's breath 02 in the chamber?
During treatments all chamber occupants may breath 02 at 45' and shallower. Tenders will hold mask to their face unfastened. When deeper than 45' one occupant must breath air!
Why does DCS or AGE initiate clotting in the blood stream?
When a bubble lodges in a vein or artery, the body interprets this as an infection and will deploy white blood cells, platelets and fibrogen to fight the 'infection'. This is why the blood begins to clot.
What is the goal of calculating helmet ventilation rates?
Keep the CO2 level below 1.5% SEV during heavy workloads.
Your diver has dyspnea?
TX: Stop working, vent the rig, adjust dial-a-breath and control breathing.
Dyspnea is (shortness of breath) usually seen during heavy workloads at depths of 120'and greater. It is caused by increased gas density and breathing apparatus resistance (dial-a-breath). It can also be caused by a build up of CO2 which causes shortness of breath.
Why is CO treacherous?
Symptoms are normally delayed until the diver begins to ascend in the water column.
Why is it important to periodically vent the divers rig when diving deeper than a 100 FSW?
The N2 narcosis may mask more serious symptoms of CO2 poisoning. The diver may not notice his shortness of breath.
Breathing limitations with diving equipment result from what?
Flow resistance (MMP) and static lung load.
What is the difference between mild and severe CO toxicity?
Severe CO poisoning will render a diver unconscious before noticing the mild symptoms of headache, tightness across the forehead, nausea and vomiting.
What is the physiological effect of hyperventilation prior to breath hold diving?
Hyperventilation lowers the CO2 in the blood which delays the normal urge to breath.
When at depth 02 concentration falls progressively as the body consumes it, this in turn lowers the level of 02 in the blood which may render a diver unconscious before he feels the urge to breath.
Five conditions necessary for barotrauma to occur?
Gas filled space
Change in pressure
Is the Oval window easily ruptured?
The Oval window is protected by the foot of the stapes so the likely hood of the Oval window rupturing is very slim.
What is the round window, what would cause a rupture, and what are the symptoms?
The round window is a membrane that separates the inner ear cavity from the middle ear cavity. The window can be ruptured by forceful valsalva or reverse over-pressurization. If the window is ruptured parylimphatic fluid can leak from the inner ear to the middle ear. The symptoms of rupture include: ringing, roaring, vertigo, nystagmus hearing loss, nausea and vomiting.
Define interstitial emphysema?
Rupture of the alveolus sacks which causes a collection of air in the lung tissues. This emphysema can easily go unnoticed.
Define mediastinal emphysema and the treatment?
This occurs when gas is forced through lung tissue into the loose mediastianl tissues in the middle of the chest.
Mild to moderate pain under the breastbone described as a deep dull ache or feeling of tightness. Deep breath, coughing or swallowing may make the pain worse. The pain may radiate to the shoulder, neck or back. Treatment:
Neuro to rule out AGE, listen to the lungs to rule out pneumothorax. 100% 02 on the surface and follow up with medical.
Define subcutaneous emphysema and the treatment?
Gas expands and leaks from the mediastinal tissue into the subcutaneous tissues of the neck.
Feeling of fullness around the neck and some difficulty swallowing. The voice pitch may change. May have apparent inflation of the neck. Treatment:
Neuro to rule out AGE, listen to the lungs to rule out pneumothorax 100% 02 on the surface and follow up with medical.
Define pneumothorax and the treatment?
Air entering the space between the lung covering and the lining of the chest wall. This will partially collapse the lung causing a pneumothorax.
Sharp unilateral pain in the chest, shoulder or upper back. Deep breathing aggravates it. Patient may breath in a rapid shallow manner, appear pale and exhibit a tendency to lean toward the involved side of the body. Treatment:
Neuro to rule out AGE, 100% 02 on the surface. Get a set of vitals If pneumothorax causes cardio respirtory problems the space may need to be vented
Define tension pneumothorax and the treatment?
Damaged lung may allow air to enter but not exit the pleural space. Successive breathing enlarges the gas pocket, which can collapse the affected lung and apply pressure to the heart and other lung. The lung shall be vented on the surface by trained medical personnel.
If tension pneumothorax is not noticed until ascent from treatment than depth of relief in the chamber is warranted until a chest tube can be inserted to relieve the pressure in the chest cavity.
Define nitrogen narcosis?
Breathing air at depths greater than 100' causes a narcotic effect upon the diver from the PPN2.
Loss of judgment
False sense of well being
Lack of concern
Tingling and vague numbness of lips, gums and legs.
N2 narcosis can be remedied by aborting the dive and ascending. As the PPN2 of air is reduced the symptoms will subside.
When is pulmonary 02 toxicity most likely to occur?
Long deep dives, or when more than 60 % 02 is breathed at one atmosphere for 24 hours or more i.e. table 4,7,8 or back-to-back table 6. If the patient is on a treatment and complains of sub-sternal burning the supervisor can tailor the O2 breathing periods to 20min followed by a ten minute air break. This can be done until the patient complains of sub-sternal pain.
What is the minimum ATA CNS 02 toxicity can occur?
Can occur when divers are exposed to 1.6 ATA of PP02 (20fsw). This is why O2 mixtures for mixed gas diving are kept below 1.3 ATA PPO2.
Why would a diver show symptoms of CNS 02 toxicity during or after a CO2 hit?
High levels of CO2 dilate the arteries causing an excessive amount of oxygen to flow through the brain increasing the likely hood of CNS 02 toxicity.
What factors can cause CO2 buildup in a dive rig?
Failure of CO2 absorbent canister, excessive amounts of CO2 in the gas supply, or inadequate ventilation of the rig.
You have removed a patient from O2 because of a CNS 02 toxicity hit, how much time will lapse before it is safe to assume a convulsion will not follow?
2 to 3 minutes.
List the direct bubble effects?
Direct blockage of arterial blood supply (AGE).
Direct blockage of venous blood supply, which causes slow blood flow and spinal cord DCS. (Type2)
Bubbles causing direct pressure on surrounding tissue, which also causes spinal cord DCS (Type 2).
Bubbles blocking blood flow to the lungs causing pulmonary DCS. (Chokes, Type 2).
List the indirect bubble effects?
Leaky blood vessels causes the blood to thicken.
White blood cells, platelets and fibrogen are released on the bubble causing the blockage.
Injured tissue releases fat that clumps together causing blockage in the blood stream.
Injured tissues also release histamine, which causes swelling in the surrounding tissues.
Define middle ear oxygen absorption syndrome, it's causes and symptoms?
After a long oxygen dive, tissues in the middle ear absorb oxygen. The estuation tube may not spontaneously open thus causing a negative pressure in the middle ear.
Symptoms include: mild discomfort, hearing loss, and a moist cracking sensation as a result of fluid in the middle ear. No treatment is necessary other than follow up with a DMO.
List the possible causes of a dizzy diver?
Transient vertigo: ABV or caloric
Persistent vertigo: IEB, or cerebral DCS (staggers)
Gas Related: CO poisoning, CO2 poisoning, Hypoxia or N2 narcosis, O2 toxicity, Dyspnea
Temperture related: Mild Hyperthermia.
Can decompression diving be conducted in SCUBA?
Yes, only if no other option exists and approved by the CO or OIC.
What is the length and color of an octopus?
The length and color is at the discretion of the diving supervisor.
What is the minimum SCUBA cylinder authorized for use?
Fifty cubic feet is the minimum cylinder authorized. SEAL teams are authorized smaller cylinders for special operations.
Is a submersible gauge required for a J valve / K valve?
A pressure gauge is only required for a K valve.
At what cylinder pressure must a dive be terminated?
A dive will be terminated when a single bottle reaches 500 PSIG and twin bottles reach 250 PSIG.
Can a knife be secured to a weight belt?
No, if the weight belt is released you will lose your knife.
Where should the tending line be tied to the diver?
It should be tied around the diver, never to a piece of equipment that could be ripped away.
Can compressed air be procured from a commercial source?
Yes, in the absence of appropriate Navy sources. Refer to 7-4.2 in chapter 7 of USN Dive Manual.
What are the charging rates for submersed and dry SCUBA bottles?
Not to exceed 200 PSIG/ min. for dry cylinders and not to exceed 400 PSIG/min. for submersed bottles.
How is a water entry made into unfamiliar water?
Whenever possible the use of a ladder should be employed using SCUBA in unfamiliar water.
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