3-3. DEFINITIONS

a. Hazardous Locations. Hazardous locations are those rooms in which either combustible anesthetic agents or disinfecting agents are stored and the areas in anesthetizing locations extending upward to five feet from the floor.

b. Anesthetizing Location. These are areas in the hospital where combustible anesthetic agents are administered to patients. Operating rooms, delivery rooms, anesthesia rooms, and rooms used for preoperative preparation of patients are included in these locations. Also included are corridors, utility rooms, and other areas used for the induction of anesthesia.

3-4. CONDITIONS PRODUCING EXPLOSIONS

Three conditions must be present to produce an explosion–first, a flammable agent (gas, vapor, or liquid) must be present; then, there must be a source of ignition as well as oxygen or a substance providing oxygen. (See figure below of explosion representation). The elimination of any one of these conditions is an important factor in the prevention of explosions.

NOTE: The above figure is representative of an explosion.

3-5. ELIMINATION OF COMBUSTIBLE (FLAMMABLE) AGENTS

a. Anesthetic Agents. Standard anesthetic agents that are flammable are ethyl ether, vinyl ether (divinyl) oxide; trade name–Vinethene), and ethyl chloride. Flammable agents that are not standard items are cyclopropane and ethylene. As a means of eliminating the danger associated with the use of these agents, the excess concentration of gas, vapor, or liquid fumes may be reduced. Ventilating or air-conditioning systems which provide complete exchanges of air will aid in reducing the concentration of gases and prevent the formation of pockets of gas in the room.

(1) Ether is easily spilled because it is liquid and its fumes may then collect near the floor as well as near the anesthesia area. Care must be exercised that this agent is not spilled on the drapes or blankets used for covering the patient because of the serious fire hazard.

(2) Other methods of elimination of gas concentration are the use of closed techniques in the administration of anesthetics and the use of nonflammable anesthetic agents. Both of these methods are the responsibility of the anesthetist.

b. Disinfecting Agents. Tinctures of disinfectants such as tincture of iodine and tincture of merthiolate are combustible. Improper use of these disinfectants (for example, spilling, using an excessive amount in skin preparation, or tipping containers) is a source of danger. Aqueous germicides are recommended for use rather than tincture disinfectants.

3-6. ELIMINATION OF SOURCES OF IGNITION

a. Sources of Ignition. The main sources of ignition include electrostatic spark (which is the most common), fixed and portable electrical equipment, and open flames or heat above the temperature at which gases will ignite.

b. Electrostatic Spark. Electrostatic spark is caused by friction between unlike and nonconductive objects or materials. Everyone is familiar with sparks which are seen and felt when an individual combs his hair, shuffles his feet across a rug, or slides in or out of his car on a cold dry day. For purposes of this discussion, the precautions that must be observed to eliminate these electrostatic sparks are of two categories. The first category (c, below) emphasizes those precautions, which must be observed by the OR personnel; the second category (d, below) emphasizes the precautions to be observed in the construction of the OR, its equipment, and use. All are important.

c. Precautions To Be Observed By Personnel.

(1) The hair must be covered completely. Operating room personnel must wear a cap or hood; the patient’s hair should be covered with a cap or a cotton hand towel that is pinned about the head.

(2) Materials that accumulate static (wool, nylon, rayon, sharkskin, silk, or plastics) must not be worn. However, hose and underclothing of these fabrics whose entire surfaces are in contact with the skin are permitted. Slips or petticoats must be made of cotton because of their free-hanging skirts. Outer garments must be made of cotton.

(3) Conductive shoes should be worn. If this type of shoe is not available, conductive stick-ons, slip-ons, or booties may be worn with ordinary shoes. Shoes must not have ferrous (iron) nails because of the danger of percussion sparks. Conductive shoes, etc., are not conductive if the shoes are covered with an accumulation of wax, dust, or dirt. Soles should be cleaned at regular intervals, usually daily, with a detergent solution. Each day, the shoes should be tested for conductivity on the conduct meter.

(4) No woolen blankets are permitted in the OR. Cotton blankets only are to be used and they should not contain synthetic fibers (dacron, nylon, and so forth) or have bindings of these materials. Blankets should be opened slowly and carefully, never flipped. Blankets should not be warmed because heating removes moisture, thus increasing the possibility of electrostatic spark.

(5) Personnel should avoid any unnecessary motion in the area near the patient’s head and the anesthesia equipment. They should stay away from the anesthetist and anesthetizing equipment as much as possible.

(6) When draping the patient and during the operative procedure, care must be exercised that the drapes do not come in contact with the breathing bag of the anesthesia machine; such contact may result in an explosion.

(7) Any contact with the anesthetist or with the patient is to be made by first touching the anesthetist’s stool, the operating table, or the patient’s skin at least two feet from the mask on the patient’s face. Any electrostatic charge within the individual is then dissipated before he is close to the anesthesia equipment or mask.

(8) Extreme caution should be used when moving anesthesia equipment. Equipment is moved only under the direction of the anesthetist.

(9) The humidity of the facemask, tubes, or breathing bag may be raised by flushing them with water. This is a responsibility of the anesthetist and may be done as an added precaution against accumulation of static charge within the machine itself.

d. Precautions Observed in Construction of the Suite and Equipment.

(1) Conductive flooring, usually ceramic or vinyl plastic tile, is installed. Such flooring disperses static charges but does not subject personnel to electrical shock. After being cleaned with detergent solution, this type of flooring must be thoroughly rinsed to prevent the accumulation of a soap film. It is never waxed except with a wax prepared especially for conductive flooring. Ordinary waxes or soap film will lower its conductivity. The floors should be checked for conductivity at least once a month.

(2) Furniture is made of metal with the leg tips or casters made of either metal or conductive rubber to provide a conductive path to the floor. Casters must be kept clean because they will lose their conductivity if allowed to accumulate dirt, wax, lint, suture material, or other debris. Clean casters usually function properly, but if the casters must be lubricated, a small amount of dry graphite or graphite oil should be used. Furniture is not to be painted or lacquered.

(3) Carbon-permeated rubber mattresses, pillows, and sheeting should be used. The leg strap for the operating table should be made of conductive material. All of the rubber parts on the anesthesia equipment should be made of conductive rubber including the breathing tubes, the breathing bag, and the face masks.

(4) An instrument (ohmmeter) is used to measure the electric resistance of personnel and equipment.

(5) All plugs, sockets, and switches must be explosion-proofed for use in anesthetizing locations.

(6) Only electrical equipment that has been designed for use in hazardous locations may be used. This includes extension cords used with portable equipment. All electrical equipment for use in an individual OR is checked daily by the OR specialists assigned to that room. Any faulty equipment is to be reported to the NCOIC immediately and is not to be used until it has been repaired. The equipment is checked routinely once a month by the maintenance department.

(7) The electric cautery is to be used with extreme care. Flammable agents such as tincture disinfectants should not be used in the final skin preparation. The switch and control of the cautery must be at least three feet from the anesthesia machine and mask. The patient must be draped in such a manner that a barrier is between the area where anesthetic mixtures are being given and the area where the cautery is being used. Only moist sponges, usually saline, are permitted in the operative field when the cautery is in use.

(8) Extreme care must be exercised when high voltage equipment (such as the X-ray, fluoroscope, electric bone saw, or dermatome) is being used.

(9) The use of photoflash and photoflood bulbs should be prohibited.

(10) Any departure from the safety rules in the use of equipment such as cautery, X-ray, fluoroscope, and so forth, must be approved by the anesthetist.

(11) Anesthesia machines or oxygen cylinders are never to be completely covered. The cover will confine any gas or oxygen, which may have leaked from the cylinder when the cover is removed; an electrostatic spark may be created which will ignite the gas that has been confined under the cover.

(12) Anesthesia equipment must be kept in good repair and must be leak proof. The care of this equipment is the responsibility of the anesthesia department. The equipment is usually checked at least once a month by the medical maintenance department.

(13) Anesthesia machines, compressed gas cylinders, and containers of flammable liquid are to be kept away from radiators, steam pipes, or other sources of heat. These should not be stored in the same room or area with oxygen or nitrous oxide cylinders.

(14) Oil or grease is never to be used on any part of the anesthesia machine or oxygen valve.

(15) The humidity of the OR should be kept at 55 to 60 percent to lessen the accumulation of static charges.

e. Elimination or Control of Sources of Heat. Sources of heat should be rigidly controlled or entirely eliminated, if possible to reduce to a minimum another factor which may cause an explosion.

(1) No smoking should be permitted in hazardous area.

(2) Open flames such as lighted matches or alcohol lamps may be used in some operative procedures but only after their use has been cleared by the anesthetist.

(3) Electric hot plates should never be used in the same room or area where flammable agents are stored or used.

3-7. ELIMINATION OF HIGH OXYGEN CONCENTRATION

a. Discussion. High oxygen concentration, whether caused by extended use or by improper handling of oxygen cylinders, must be reduced to a minimum.

b. Ventilating or Air-Conditioning Systems. Systems should be provided which permit complete exchanges of air.

c. Oxygen Cylinders. Oxygen cylinders must be operated properly. The precautions that must be observed when handling oxygen cylinders and regulators to prevent high concentrations and explosions or fire are as follows:

(1) Never permit oil, grease, or readily combustible materials to come in contact with oxygen cylinders, valves, regulators, gauges, or fittings.

(2) Never lubricate regulators, fittings, or gauges with oil or any other combustible substance.

(3) Never handle oxygen cylinders or apparatus with oily hands, greasy gloves, or dirty rags.

(4) Always clear the particles of dust and dirt from the opening to each cylinder by just barely opening and closing the valve before applying any fitting to the cylinder. (This is called “cracking” the valve. The specialist should point the valve opening away from his face while cracking the valve.)

(5) Never permit oxygen to enter the regulator suddenly; open the valve slowly. The regulator reduces the pressure of oxygen to a low pressure that is safe to use; it ensures a steady, even flow of oxygen; and it provides a means for adjusting the rate of flow.

(6) Never drape an oxygen cylinder with any materials such as hospital gowns, masks, caps, sheet, plastic material.

(7) Never use oxygen fittings, valves, regulators, or gauges for any other service except oxygen.

(8) Never mix gases of any type in a oxygen cylinder or in other type cylinder.

(9) Never use oxygen from a cylinder except through a pressure-reducing regulator.

(10) Never attempt to use regulators that are in need of repair and do not attempt to use cylinders having valves that do not operate properly. They can be removed. The common types of accidents due to hazards other than fire and explosion and the measures used to prevent them are discussed below.

(11) Never attempt to repair defective oxygen equipment, unless properly qualified by knowledge and experience.

3-8. FIRE EXTINGUISHERS

Table 3-1 lists the fire extinguishers used for different types of fire that may occur in the OR. The OR specialist should know the location of these extinguishers and be thoroughly familiar with their operation.