<prompt> Cardiac or central nervous system toxicity may result when standard lidocaine doses are administered to patients with circulatory failure. This may be due to the following reason:Lidocaine concentration are initially higher in relatively well perfused tissues such as brain and heaHistamine receptors in brain and hea gets suddenly activated in circulatory failureThere is a sudden out-burst of release of adreneline, noradreneline and dopamine in brain and heaLidocaine is conveed into a toxic meta-bolite due to its longer stay in liver.  <response>: A i.e. Lidocaine concentration are initially higher in relatively well perfused tissues such as brain and hea - The highly perfused organs as Brain, Lung, Liver, Kidney, hea are responsible for initial rapid uptake Alpha phase which is followed by a slower redistribution Beta phase to moderately perfused tissues muscle and gut. Amide Local anaesthetics lidocaine are metabolzied by Microsomal enzymes in liver Decrease in hepatic function eg cirrhosis or blood flow eg. congestive Hea failure will reduce metabolic rate and predispose patients to systemic toxicityQ Toxicity of Lidocaine is due to its own concentration in blood not due to its toxic metabolite that is why option 4 is wrong. 