Bym 501 e fundamentals of biomedical engineering Saman

Bym 501 e fundamentals of biomedical engineering Saman ahdi rezaeieh Masters of biomedical engineering at itü Prof. dr. inci f. çilesiz

Contents • • Electrical safety Microshock Mickroshok hazards Leakage current Conductive surfaces References Thanks

Electrical safety Medical procedures usually expose the patient to more hazards than the typical home or work place because 1. Skin and mucous membrances 2. Sources of hazards like ü fire, air, earth, chemicals, drugs ü sound and electricity ü gravity and mechanical stress ü human

What is microshock? • Microshock is a very low level current applied directly to the heart. This can lead to inadvertent fibrillation and death. Microshocks are usually a very low magnitude current, about tens of microamperes. • Microshock is a risk in patients with intracardiac electrical conductors, such as external pacemaker electrodes, saline filled catheters, or weak or old heart tissue within the heart. A current as low as 10 u. A (microampere) directly through the heart, may send a patient directly into ventricular fibrillation

Microshok hazards • If ground wire is broken, the chassis potential rises above the ground; a patient who has a grounded connection to the heart (e. g. through a catheter) receives a microshock if he touches the chassis. • If there is a connection from the chassis to the patient’s heart, and a connection to the ground anywhere in the body, this also causes microshock. • The hazard for microshock only exists if there is a direct connection to the heart. Otherwise, even the internal resistance of the body is high enough to prevent the microshocks.

Leakage current It is a current that flows from AC or DC Input or output

Leakage current in patient leads • Limits on leakage current in patient leads should be 50µA. • Isolated patients leads must have leakage current that is less than 10µA.

Currents and effects Type of Current Rate (m. A) Physiological effect Threshold 1 -5 Tingling sensation Pain 5 -8 Intense or painful sensation Let go 8 - 20 Threshold of involuntary muscle Paralysis > 20 Respiration paralysis and pain Fibrillation 80 - 100 Ventricular and heart fibrillation Defibrillation 1000 - 10000 -

Conductive paths to the heart • The following electronic devices will make microshock in case they have a connection with heart. üEpicardial or endocardial electrodes of externalized temporary cardiac pacemakers üElectrodes for measuring EGM and stimulation devices üLiquid-filled catheters placed in the heart to ü measure blood pressure ü withdraw blood samples ü inject substances such as dye or drugs into the heart

references • https: //bmet. fandom. com/wiki/Category: Electrical_safety • https: //www. slideshare. net/Yassir. Ali. Hassan/electrical-safety 41590043 • https: //www. sunpower-uk. com/glossary/what-is-leakage-current/ • https: //carelabz. com/what-leakage-current-testing-measuringhow-leakage-current-testing-measuring-done/

• Thank you