<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 circulatroy failureThere is a sudden out-burst of release of adreneline, noradreneline and dopamine in brain and heaLidocaine is conveed into a toxic metabolite due to its longer stay in liver  <response>: Ans. is a i.e., Lidocaine concentration are initially higher in relatively well perfused tissues such as brain and hea o Lidocaine is a rapidly acting drug because of its rapid distributtion to well perfused tissues such as brain and hea.o Circulatory failure is characterized by decreased cardiac output and a consequent decrease in hepatic blood flow.As a result metabolic clearance ofLidocaine in liver is diminshed and its elemination t 12 is increased. Consequently Lidocaine concentration is initially increased in these relatively well perfused tissues brain and hea even with usual doses and toxicity results. 