Welcome to our lesson on the use of tourniquets in operations. ​ A tourniquet is a device that is used to stop the flow of blood to a specific part of the body, usually an arm or a leg. Tourniquets are commonly used in surgery to allow the surgeon to operate on a specific area without being hindered by the flow of blood. ​ There are a few key reasons why tourniquets are used in surgery. Firstly, tourniquets can help to reduce bleeding during the surgery, which allows the surgeon to see and work on the area more clearly. Secondly, blood loss can be very dangerous to the patient systemically and replacing blood can have some very serious side effects. Finally, tourniquets can help to reduce the risk of infection by limiting the amount of blood that is exposed to the surgical site. ​ It is important to use tourniquets safely and appropriately. Tourniquets should only be used for a limited amount of time, as prolonged use can cause damage to the tissues and muscles. For arms, tourniquets can typically be used for up to 90 minutes, while for legs, tourniquets can typically be used for up to 2 hours. It is important to carefully monitor the tourniquet time to ensure that it does not exceed these limits. ​ Tourniquets can also be used in a technique known as a "bier block," which is used to numb a specific area of the body for a minor surgery or procedure. Local anaesthetic, which is usually dangerous if put into the circulation, is injected into a vessel to numb everything distal to the injection site. In this case, the tourniquet is applied above the site of the injection and is released once the procedure is complete and the local anaesthetic no longer poses a risk to the patient. ​ In summary, tourniquets are a useful tool in surgery that can help to reduce bleeding and the risk of infection. It is important to use tourniquets safely and appropriately, considering the recommended time limits for their use. Tourniquets can also be used in the technique known as a "bier block" to numb a specific area of the body for a minor surgery or procedure.