Body temperatures below 36C or 96.8F, where the physiology of the tissue and at the cellular level is adversely affected including the immune response (resulting in an increased risk of infection), poor clotting, reduced drug clearance and poor quality scar tissue. There are times when hypothermia is intentionally induced locally or systemically, reducing cellular activity such as after a heart attack, stroke, or during heart surgery. This reduces oxygen demand and can be protective of vulnerable tissues near the injury. However, temperature must be brought back to normal levels as soon as possible to avoid the deleterious effects of hypothermia during patient recovery.