Medical devices verification

Electrosurgical units are medical devices intended for cutting and coagulation of tissue. For their operation, they use high frequency, from 300 KHz to 4MHz, alternating current.

Depending on operating frequency, they can be divided to:

1. Classical electrosurgical units, operating frequency up to 1MHz
2. Radiofrequency electrosurgical units, operating frequency above 3MHz

Electrosurgical units are used in almost all surgical procedure in general surgery, orthopedic, gynecology, dermatology etc.

During verification of performance of electrosurgical units, the following parameters are checked:

• Output power vs. load (impedance), in all modes,
• Output power vs. power setting, in all modes,
• HF leakage current through active electrode and neutral plate
• Proper function of monitoring circuit of neutral electrode

Defibrillator is an electrical medical device intended for heart defibrillation, it determines presence or disorder of heart rhythm, and uses electric shock to normalize heart rhythm. It is used as the first aid equipment for heart attack and other heart rhythm disorders.

There are two types of defibrillators:

1. AED or automatic external defibrillator, it analyzes heart rhythm and performs defibrillation as needed
2. Conventional manual, external defibrillators

During verification of performance of defibrillators, the following parameters are checked:

• Delivered energy in J
• Charge time
• Sync time

Patient monitors are medical devices used for monitoring physiological parameters: ECG, body temperature, blood pressure, respiration, saturation, concentration of different gases in blood. Patient monitors are used in intensive care and surgical theaters, to provide information about patient’s condition to medical stuff.

During verification of performance of patient monitors, the following parameters will be checked:

1. ECG
2. Heart rate
3. Non-invasive blood pressure
4. Invasive blood pressure
5. Respiration
6. Body temperature
7. Standard SpO2

ECG devices or electrocardiographs are medical devices which records electrical activity of the heart in time. The record obtained by electrocardiograph is called electrocardiogram and it is used in medicine for diagnostics.

During verification of performance of ECG devices, the following parameters will be checked:

• Amplitude of the signal
• Heartrate

SpO2 meters or pulse oxy-meters, are devices for quick and non-invasive measuring of arterial blood oxygen saturation. Oxygen saturation is expressed in percentages, and takes value from 35% to 99%.

During verification of performance of SpO2 meters, the following parameter will be checked:

• Standard SpO2

Infusion and PCA pumps are medical devices used to deliver medicines and fluids into a patient’s body in a controlled manner. It provides control of medicines and fluid dose delivered to patient. The devices are automatic systems for measuring flow of fluid.

During verification of performance of infusion and PCA pumps, the following parameters will be checked:

• Flow, volume of fluid delivered in time
• Occlusion

Electrotherapy is modality of physical medicine, and use electric current to stimulate particular region of the body. Different current modalities (pulse form, pulse duration, pause, frequency, intensity) are used for electrostimulation, and depending on modality can reduce pain, stimulate muscles, or nerves. The most used modalities in electrotherapy are interferential currents, diadynamic currents, exponential currents, and galvanic current.

During verification of performance of electrotherapy devices, the following parameters will be checked:

• Intensity of output signal
• Waveform of output signal

In physical medicine, it is used low power lasers (to 1000mW) with different wavelengths. They produce complex photo biological effects, as increasing of bioenergetics metabolism, stimulation of microcirculation, regeneration of tissue and reducing the pain.

During verification of performance of devices for laser therapy, the following parameters will be checked:

• Power of laser beam
• Visual – form of the cross section of the laser beam

In physical medicine, ultrasound is used for therapeutic purposes. It is used ultrasound of 1MHz and 3MHz frequency, in continual or pulsed mode. Application of ultrasound has mechanical and thermal effects on treated tissue. It is applied in chronical degenerative diseases, injuries of ligaments, painful and stiffened shoulder, radial and ulnar epicondylitis.

During verification of performance of ultrasound therapy devices, the following parameters will be checked:

• Ultrasound power

Vacuum-compression devices is used in physical medicine for vacuum or pressure therapy. Application of vacuum-compression therapy increases the speed of circulation of blood and lymph. Some indications are arteriosclerosis, ulcus, polyarthritis, and scleroderma.

During verification of performance of devices for vacuum-compression therapy, the following parameters will be checked:

• Vacuum
• Pressure

Magnetic therapy devices generates low frequency magnetic field, frequency from 1 to 100Hz, and magnetic induction to 10mT. Main effects of magnetic field penetration through patient’s body are circulation improvement, increasing of partial pressure of oxygen in tissues, increasing the amount of ATP and spread of blood vessels.

During verification of performance of magnetic therapy devices, the following parameters will be checked:

• Magnetic induction intensity
• Magnetic field frequency