Lecture
The safety of personnel and patients during the operation of medical equipment items must be ensured by:
1.the design of medical equipment items, which must be safe when used separately and as part of complexes or systems and must satisfy the requirements of the standard;
2.the design and arrangement of electrical installations used to supply power to medical apparatus;
3.sufficient qualification of specially trained and certified personnel;
4.a system of maintenance and repair of medical equipment items;
5.compliance of premises with the applicable building codes and regulations for the rational organization of work.
Only specially trained, certified personnel not younger than 18 years of age, fit by state of health and qualified to perform the specified work, are allowed to independently operate medical equipment.
Personnel operating medical equipment are subject to a preliminary (upon hiring) and periodic medical examination. Personnel must have a higher specialized or secondary specialized education and a certificate of completion of courses in the type of medical equipment being operated.
Before being admitted to work, personnel must undergo an induction and initial on-the-job safety briefing, with a demonstration of rational and safe work practices, recorded in the briefing log. A repeat briefing must then be conducted no less often than every 6 months. An unscheduled briefing is applied when occupational safety rules change, when personnel violate safety procedures, and when the nature of the work changes.
Heads of structural units must develop safety instructions for each work area. They are also responsible for the operation of medical equipment devices. Operation of medical equipment without accompanying documentation is prohibited (a complete set of the documentation must be kept in the department).
Depending on the method of protection against electric shock, medical equipment items are divided into 4 classes:
Class 01: In addition to basic insulation, they have a terminal for connecting accessible touchable metal parts to an external grounding device. The mains cord plug does not have a grounding contact.
Class 1: In addition to basic insulation, they have a grounding contact. The plug has a grounding cord or terminal.
Class 2: In addition to basic insulation, they have supplementary insulation. They do not require protective grounding or neutralization. The mains cord inlet on the housing is marked with «0».
Class 3: Powered from an isolated AC voltage source of not more than 24 V or a DC voltage of not more than 50 V. They do not have a circuit with a higher voltage. They do not need neutralization or grounding of accessible metal parts.
Depending on the degree of protection against electric shock, they are divided into:
H– normal degree of protection; the equipment is not accessible to the patient;
B– increased degree of protection; the patient leakage current under normal condition of the item does not exceed 0,1 mA;
BF– increased degree of protection; isolated working part;
CF– highest degree of protection; isolated working part; used for cardiology.
If the degree of protection is not indicated on the marking or in the operating instructions, such items must be checked by engineering and technical personnel.
To protect against electric shock, all accessible touchable metal parts of class 1 and 01 apparatus with solidly grounded power supply are neutralized, and when powered from an isolated network they are neutrally grounded.
At the start of each working day or shift, engineering and technical personnel must check the condition of the protective grounding or neutralization. During a treatment procedure it is prohibited to touch the patient and the electrodes of apparatus for electric current therapy and defibrillators.
When performing electrical treatment and diagnostic procedures, personnel must eliminate the possibility of accidental grounding of the patient (touching grounded metal parts of the apparatus).
It is prohibited to leave the patient unattended during procedures. In rooms where electromedical apparatus is operated, radiators and metal heating pipes, water pipes, sewage and gas systems must be enclosed with wooden grates, and the floors must be non-conductive.
It is prohibited to connect electrical receivers to the mains if the insulation of the power cord, housing, plug, or other components is damaged.
+If a fault is detected during operation, personnel must immediately disconnect the faulty apparatus from the mains, make a corresponding entry in the maintenance log, and report to the head of the department. Personnel may work with this apparatus again only after the fault has been eliminated, and only if there is a corresponding entry by the electrical engineer in the maintenance log.
The use of adapters and extension cords is prohibited in medical institutions. It is prohibited to repair faults in apparatus that is connected to the mains. Electric hot plates with an open heating element must not be used.
Personnel and patients may be exposed to:
1.electric shock;
2.mechanical injury;
3.ionizing radiation;
4.electromagnetic radiation;
5.IR radiation;
6.UV radiation;
7.ultrasonic radiation;
8.laser radiation;
9.burns, frostbite when working with liquid nitrogen;
10.elevated levels of noise and vibration;
11.chemical effects;
12.biological effects.
Systematic exposure of operating personnel to an ultra-high frequency (UHF) or microwave (SHF) field with an intensity exceeding permissible levels disrupts the steady-state condition of the human nervous and cardiovascular systems. When performing UHF procedures, precise tuning of the therapeutic circuit into resonance with the generator is required. The total gap between the electrodes and the patient's skin must not exceed 6 cm. Detuning the output circuit to reduce the apparatus's output power is not permitted.
UHF and microwave therapy apparatus with an output power of more than 100 W must be operated in specially designated rooms or shielded cabins in which the apparatus and the patient are located.
To reduce radiation into the surrounding space, high voltage must be applied to the generators only after the emitter has been positioned correctly relative to the irradiated area of the body. The size and shape of the emitter must correspond to the irradiated area of the body. To protect the patient's eyes during microwave irradiation of the head area, protective goggles of the ORZ-5 type must be used.
When ultraviolet (UV) emitters are in operation, the eyes of personnel and patients must be protected with closed protective goggles. Between treatment procedures, the reflectors of mercury-quartz emitters with lamps must be closed with the shutters provided on them or with dense black fabric material.
During infrared (IR) irradiation of the facial area, the patient is fitted with goggles made of thick leather or cardboard.
It is prohibited to place an IR or UV radiation lamp directly above the patient; it must only be placed at a distance that prevents fragments from hitting the patient's body.
+During systematic work with ultrasound (US) for more than 50% of the working time, a 15-minute break must be arranged every 1.5 hours, which may be filled with other work not related to ultrasound. Direct contact of the personnel's hands with the medium in which ultrasonic oscillations are excited must be used. When performing ultrasound procedures, personnel must work in cotton gloves. To eliminate the harmful effect of ultrasonic oscillations on the personnel's hands when performing underwater ultrasound procedures, personnel must put rubber gloves on over the cotton gloves. It is prohibited to touch the working part of the ultrasonic emitter while the apparatus is switched on.
The head of the institution must appoint a responsible person to ensure the serviceable condition and safe operation of the laser. Class 2-4 lasers must be accepted by a commission prior to commissioning, with the mandatory inclusion of a representative of the state sanitary inspectorate.
Depending on the hazard level of the generated radiation, lasers are divided into 4 classes:
1) the output radiation does not pose a hazard to the eyes and skin;
2) the output radiation poses a hazard when the eyes are irradiated by direct or specularly reflected radiation;
3) the output radiation poses a hazard when the eyes are irradiated by direct, specularly reflected, or diffusely reflected radiation at a distance of 10 cm from the diffusely reflecting surface, or when the skin is irradiated by direct or specularly reflected radiation;
4) the output radiation poses a hazard when the skin is irradiated by diffusely reflected radiation at a distance of 10 cm from the diffusely reflecting surface.
When operating class 2-4 lasers, protective goggles with light filters, interchangeable depending on the wavelength of the laser radiation, must be used.
In the event of a single failure of protective means, the patient leakage current must not exceed 5*10-2mA. Radiological equipment of the UF type must be used when performing intracardiac interventions.
When it is necessary to use any class 01 or class 1 diagnostic devices, personnel must carefully check the integrity of the circuit and its protective grounding. Class 2 electromedical apparatus with a patient leakage current of less than 10 uA may be used for therapy and diagnostics of an electrically vulnerable patient. If class 2 apparatus has a leakage current greater than 10 uA, such apparatus must have a connection to grounded devices.
When connecting an «artificial heart» apparatus to a patient, it is prohibited to simultaneously touch the tap of the hydraulic system and the patient.
To prevent burns to the patient under the passive electrode of an electrosurgical apparatus, it is necessary to:
1.Ensure that the passive electrode fits snugly against the patient's body over its entire surface, i.e. create good electrical contact over the entire area of the passive electrode with the body for the whole duration of the operation.
2.It is prohibited to apply an electrode of smaller area than specified in the apparatus's technical description to the patient. The maximum specific power of the apparatus must not exceed 1,5 W/cm2. The passive electrode must be positioned as close as possible to the operating field. During the operation, periodically check its contact with the patient's body. Before placement, it is necessary to ensure that the surface of the passive electrode is free of corrosion, contamination, folds and irregularities.
3.It is necessary to degrease the patient's skin at the site of application of the passive electrode and moisten it with saline solution, ensuring a low transition resistance of about 1 Ohm between the electrode and the body.
4.Before each operation, check the operability of the electrosurgical apparatus, and the functioning of its control and monitoring components.
5.The high-frequency generator must be switched on only for the duration of coagulation or cutting. It is prohibited to keep the generator switched on during pauses between exposures.
6.It is prohibited to check the operability of the electrosurgical apparatus by sparking, by touching the active electrode to grounded objects.
7.Accidental contact of the patient's body with grounded parts of the operating table and other grounded equipment must be excluded. For this reason, the operating table and its metal parts must be covered with sponge rubber or two to three layers of oilcloth.
+8.In the event of ineffective action of the high-frequency current, it is prohibited to increase the apparatus's output power without first checking for a break in the electrode circuit (check the reliability of the connection of the wires, of the patient to the apparatus, and of the electrode holder).
When several types of electromedical apparatus are connected to a patient, if the necessary measures are not taken, the probability of the patient being subjected to electric shock significantly increases, and disruptions to the normal functioning of diagnostic devices are also possible. It is prohibited to use apparatus intended for technical purposes in combination with electromedical apparatus that has a functional connection with the patient or a galvanic link between the apparatus.
To prevent burns to the patient under the electrodes of an EEG machine and an ECG machine during joint operation with an electrosurgical apparatus, engineering and technical personnel should connect high-frequency chokes with an inductance of 3-4 mH or resistors of 470 kOhm. The electrodes of the diagnostic devices must be positioned as far as possible from the operating field and the electrodes of the electrosurgical apparatus.
+When several types of items are in simultaneous electrical contact with the patient's body, items with an isolated working part of type BF and CF must be used to ensure electrical safety.
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