The cardiovascular system is also responsible for moving heat from the core to the skin where heat is lost by several physical processes in the form of conduction, convection, radiation and evaporation of sweat. In addition the body heat load must be dissipated at a rate equal to its production to maintain the body's normal physiological range of temperatures. This ability to remove heat by increasing the skin blood flow may see a shift of cardiac output up to near 30% to the skin,7 reaching levels of up to 6–8 L/min15 resulting in a proportionate drop in flow to the gastrointestinal tract,16 leading to gut ischaemia and increased gut permeability.