Thank you for your question.
Standstill operation is also known as hypothermic cardiac standstill operation. This is a surgical procedure that involves cooling the body to 15 degrees Celsius and stopping blood circulation.
When the body is cooled to 15 degrees Celsius, the heart stops beating(cardiac arrest) and blood stops circulating. Although there is no blood flow, the small capillaries in the body is still able to keep the tissues alive.
The surgeons that perform the necessary operation(e.g. repairing an aneurysm). After the procedure, the patient's body is brought back to normal temperature.
The cooling of the body is achieved by injecting a cold solution(4 degrees celsius) into the veins of the patient. The solution contains a mixture of blood and a gel-like material(crystalloid).
Warming of the body is achieved by instilling warm blood into the body.
In most cases the procedure should last less than one hour to avoid complications.
I hope this answers your question.