Final answer:
The minimum microshock required to cause v-fib is 100 µA, which is extremely low compared to the general threshold of sensation for electric shock and necessitates strict safety precautions during surgeries.
Step-by-step explanation:
The minimum microshock required to produce ventricular fibrillation (v-fib) is 100 µA. In the context of surgery and patient safety, even a small current of 20 µA applied directly to the heart may cause v-fib, as it bypasses the body's resistance and directly stimulates cardiac tissue. This indicates that even lower currents than the threshold for sensation, which is around 1 mA, can be dangerous if they are directly applied to the heart muscle. Therefore, while regular shocks below 5 mA may not harm external skin, it's critical to understand that the heart is especially sensitive, and direct currents as low as 100 µA can be life-threatening.
The requirement of safety precautions is underscored by the knowledge that relatively low voltage can lead to hazardous current levels due to the heart's low resistance during procedures like open-heart surgery. Detailed protocols and preventive measures must be strictly adhered to in order to avoid these risks. Specially designed equipment and monitoring systems often facilitate maintaining electrical safety in clinical environments.