Table 9.3 Liquefied Gas groups — for medicial first aid purposes
| MFAG TABLE | 310 Hydrocarbons | 340 Chlorinated hydrocarbons | 365 Aliphatic oxides | 620 Liquefied gases | 725 Ammonia | 740 Chlorine |
| P | Butadiene | Vinyl chloride | Ethylene oxide | Methane | Ammonia | Chlorine |
| R | Butane | Propylene oxide | ||||
| O | Butylene | |||||
| D | Ethane | |||||
| U | Ethylene | |||||
| C | Propane | |||||
| T | Propylene |
In the MFAG, each of the main categorisations (as listed along the top row of Table 9.3) has medical first-aid advice attached to it. This is divided into general advice, signs & symptoms and treatment. If a person is affected by any of the gases listed, it is the tables in the MFAG which should be consulted. With regard to medical treatment, the MFAG has recommended advice for:—
• Inhalation
• Skin contact
• Eye contact, and
• Ingestion
The main points to be remembered in treating patients for gas poisoning or asphy-xiation are outlined below (other points are covered later):
Treatment for asphyxia and inhalation of toxic fumes
Remove the casualty at once from the dangerous atmosphere — ensure that rescuers are equipped with self-contained breathing apparatus so that they do not become the next casualty.
To check that the patient is breathing tilt the head firmly backwards as far as it will go to relieve obstructions and listen for breathing with the rescuer's ear over the patient's nose and mouth.
Patient not breathing
• Give artificial respiration at once
• Give cardiac compression if the pulse is absent
Patient breathing but unconscious
• Place the patient in the unconscious position
• Check there are no obstructions in the mouth
• Remove any dentures
• Insert an Airway; leave in place until the patient regains consciousness
• Give oxygen. (See the sub-section which follows)
• Keep the patient warm
• Give nothing by mouth
• Give no alcohol, morphine or stimulant
Patient conscious but having breathing difficulty
• Place the patient in a high sitting-up position and keep warm
• Give oxygen. (See the sub-section which follows)
If breathing does not improve despite these measures, then asphyxia or other lung problems may have occurred. In such circumstances, or if the patient's condition deteriorates rapidly, obtain medical advice.
9.3.4 Oxygen therapy
Oxygen resuscitators
Oxygen resuscitators are used to provide oxygen-enriched respiration to assist in the recovery of victims overcome by oxygen deficiency or toxic gas. The equipment can be taken into enclosed spaces to give immediate treatment to a casualty. Oxygen resuscitators consist of face mask, pressurised oxygen cylinder and automatic controls to avoid damage to the victim and give audible warning in the event of airway obstructions. The equipment is provided with a standard eight-metre long extension hose so that the carrying case (with cylinder and controls) may be securely placed and the mask taken to the victim if he is lying in a confined location. Some ships provide a further 15-metre extension hose. If the equipment is taken into a contaminated atmosphere, it must be remembered that, if adjustable, the instrument must be set to supply only pure oxygen. Caution with its use in a flammable atmosphere is necessary. If the instrument is used when the victim has been removed from the contaminated space, there are means to vary the air/oxygen mix.
It should be noted that the couplings on oxygen resuscitators should not be greased.
Warning: Smoking, naked light or fires must not be allowed in the same room during the administration of oxygen because of the risk of fire.
Oxygen must be given with care since it can be dangerous to patients who have had breathing difficulties such as bronchitis.
An accident in which a patient may require oxygen can be divided into two stages:
Stage 1 — During rescue
During rescue the patient should be connected to the portable oxygen resuscitation apparatus and oxygen administered until transferred to safety.
Stage 2 — When the patient is in a safe room
The unconscious patient
1. Ensure there is a clear passage to the lungs and that an Airway is in place
2. Place mask over the nose and mouth and give 35 per cent oxygen
3. Connect the mask to the flowmeter and set it at 4 litres per minute
The conscious patient
1. Ask if the patient suffers with breathing difficulty. If the patient has severe bronchitis, then give only 24 per cent oxygen. All others should be given 35 per cent oxygen
2. The mask is secured over the patient's mouth and nose
3. The patient should be placed in the high sitting-up position
4. Turn on the oxygen flowmeter to 4 litres per minute
Oxygen therapy should be continued until the patient no longer has difficulty in breathing and has a healthy colour. If the patient has difficulty in breathing, or if the face, hands and lips remain blue for longer than 20 minutes, seek urgent medical assistance.
Additional measures necessary where exposure to toxic vapours has been experienced include:—
• The removal of affected clothing
• Eye washing, and
• Skin washing
9.4 FROSTBITE
The extreme coldness of some liquefied gases is, in itself, a significant hazard. If the skin is exposed to severe cold, the tissue becomes frozen. This danger is ever-present
in gas terminals and on a ship handling fully refrigerated cargoes. For fully pressurised gases, while containment systems will normally be at or near ambient temperature, liquid leaks will quickly flash to the fully refrigerated temperature. Such areas should never be approached without proper protective clothing.
The symptoms of frostbite are extreme pain in the affected area (after thawing), confusion, agitation and possibly fainting. If the affected area is large, severe shock will develop.
Initial symptoms
• The skin initially becomes red, but then turns white
• The affected area is usually painless, and
• The affected area is hard to the touch
If the area is left untreated, the tissue will die and gangrene may occur.
Treatment
• Warm the area quickly by placing it in water at 42°C until it has thawed*
• Keep the patient in a warm room
• Do not massage the affected area
• Severe pain may occur on thawing: give pain killer or morphine if serious
• Blisters should never be cut, nor clothing removed if it is adhering firmly
• Dress the area with sterile dry gauze
• If the area does not regain normal colour and sensation, obtain medical advice
* As immediate action is necessary, and without the warm water close to hand, in the first instance the affected part can be warmed with body heat or woollen material. If the finger or hand has been affected, the casualty should hold his hand under his armpit. Blood circulation should be allowed to re-establish itself naturally. If appropriate, the casualty should be encouraged to exercise the affected part while it is being warmed.
9.5 CHEMICAL BURNS
As shown in Table 9.2, chemical burns can be caused by ammonia, chlorine, ethylene oxide and propylene oxide. The symptoms are similar to burns by fire, except that the product may be absorbed through the skin causing toxic side-effects. Chemical burning is particularly damaging to the eyes.
Symptoms
• A burning pain with redness of the skin
• An irritating rash
• Blistering or loss of skin
• Toxic poisoning
Treatment
• Attend first to the eyes and skin
• Wash the eyes thoroughly for ten minutes with copious amounts of fresh water
• Wash the skin thoroughly for ten minutes with copious amounts of fresh water
• Cover with a sterile dressing
Otherwise, the treatment is as for burns, details of which are contained in the IMO Medical First Aid Guide (see Reference 1.7).
On gas carriers authorized to transport these products, deck showers and eye baths are provided for water dousing; their locations should be clearly indicated.
9.6 TRANSPORT TO HOSPITAL
It is extremely important to label the patient adequately before removal from the ship or terminal and a specimen patient-label is shown in Figure 9.1.
| For the guidance of Medical Officer |
| 1. Name of Patient........................................................... Age................... |
| Home Address .......................................………………………................... |
| Name of Ship ...................Port.................. Next Port ...........……............. |
| Name and Address of Shipowner and Ship's Agent |
| 2. Above person was exposed to ........................................................gas |
| at ......am/pm on (Date) ....................................................19 ..............….. |
| 3. Brief summary of first aid treatment given …………………………………………………………………… …………………………………………………………………… …………………………………………………………………… |
Figure 9.1 Patient label
9.7 HAZARDOUS ATMOSPHERES 9.7.1 The need for gas testing
The atmosphere in enclosed spaces must be tested for oxygen and hydrocarbon content in the following circumstances:
• Prior to entry by personnel (with or without protective equipment)
• During gas-freeing, inerting and gassing-up operations
• As a quality control before changing cargoes, and
• To establish a gas-free condition prior to drydock or ship repair yard
The atmosphere in a cargo tank is rarely, if ever, homogeneous. With the exception of ammonia and methane, most cargo vapours at ambient temperatures are denser than air. This can result in layering within the cargo tank. In addition, internal structures can hold local pockets of gas. Thus, whenever possible, samples should be drawn from several positions within the tank.
Atmospheres which are inert or deficient in oxygen cannot be checked for flammable vapours with a combustible gas indicator. Therefore, oxygen concentrations should be checked first, followed by checks for flammable and then toxic substances. All electrical instruments used should be approved as intrinsically safe.
9.7.2 Oxygen analysers
Several different types of oxygen analyser are available. A common type of analyser is illustrated in Figures 9.2(a) and (b). In this example, oxygen diffuses through the teflon membrane into a potassium chloride solution and activates the chemical cell. When the switch is closed, current flows round the circuit and deflects the ammeter needle. The more oxygen absorbed by the solution, the greater the current and the needle deflection indicates the percentage of oxygen in the atmosphere being sampled.
The instrument described above operates without batteries and is relatively insensitive. Other types of analysers include the polarographic and paramagnetic-type instruments. These are much more sensitive and require batteries.
It should be noted that batteries should never be changed in a gas dangerous zone. Such instruments have dual scales, each having a separate function. For example:—
• Scale 1 — oxygen deficiency in air — zero to 25 per cent oxygen by volume;
• Scale 2 — oxygen in nitrogen — zero to 1 per cent oxygen by volume.
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