CNS |
Ventilatory stimulation |
General anaesthesia at high levels |
Cerebral vasodilation |
Increased intra-cranial pressure |
Increased sympathetic tone |
Decreased parasympathetic tone |
Increased adrenal medullary and cortical output |
Cardiovascular |
Direct effects |
Impaired contractility of cardiac and vascular smooth muscle |
Reduced afterload and systemic vasodilation |
Opposing consequence of heightened sympathetic tone |
Increased cardiac frequency |
Increased myocardial contractility |
Increased venous capacitance vessel tone |
Increased venous return |
Increased cardiac output |
Metabolism |
Reduced oxygen consumption |
Altered cellular fuel utilisation |
Increased cellular ketoacid and lactic acid uptake |
Renal/electrolyte |
Increased H+ secretion and HCO3 reabsorption |
Renal adrenergic-mediated vasoconstriction at high levels |
Increased Na+ reabsorption |
Mild hyperkalemia |
Blood |
Small increase in haematocrit/haemoglobin concentration |
Reduced haemoglobin O2 affinity (increased p50) |
Suppression of erythropoietin release |