Malignant Hyperthermia:

Farida Mohamed Mohamed Azmy

Malignant hyperthermia, which is called the ”nightmare”syndrome of anaesthesiologists is an acute-threatening syndrome,it is a subclinical myopathy that is unmasked upon exposureof the potent inhalational anaesthetic agents and succinylcholineskeletal muscle acutely and unexpectedly increasesits oxygen consumption and lactate production resultingin greater heat production, respiratory and metabolic acidosis,muscle rigidity, sympathetic stimulation, and increasedcellular permeability.Its exact mechanism is still being debated. The mostaccepted theory is that MH is caused by an inability tocontrol calcium concentrations within the muscle fibre andthat it may involve a generalized alteration in cellular orsubcellular membrane permeability. Close monitoring of patientsspecially in susceptible individuals should be carriedon in order to detect M.H.as early as possible and to performrapid interference to stop the process.Diagnosis of malignant hyperthermia is based on clinicalpicture which includes extraordinary temperature, musclerigidity,unexplained tachycardia,increase in end-tidal carbondioxide and unexplained myoglobinuria in the postoperativeperiod.Laboratory investigations as serum CPK which may beraised, it will be suggestive, if normal it is no indicativeand ~e have to restore to muscle biopsy.Specific treatment is the action of dantrolene on musclecalcium movements, symptomatic treatment is by reversal ofacid-base and temperature change.Evaluation of affected families is guided by movements ofcirculating creatine phosphokinase and by analysis of drug-induced contractures in muscle biopsy specimens.Either general or regional anaesthesia is safe for patientssusceptible to M.H,provided that if a general techniqueis chosen, care is taken to specially prepare the anaesthesiamachine and to avoid all anaesthetic trigger agents.Challenges for the future include identification of thegene or genes responsible for M.H. and eludication of the mechanismthat links exposure to the subsequent loss of calciumWe hope that continuing research will reveal the answers tomany if these mysteries, so that the next generation of anaesthesiologistswill consider the description and conquest ofM.H. an interesting aspect of anaesthesia history.