👁➖BE AWARE OF AWARENESS ➖👁

💣Premeditation  with amnestic reduces the chance of awareness. Also, if awareness occurs, psychological trauma is less likely without recall. 

💣Light induction doses and liberal use of muscle relaxants ,without giving adequate concern to the depth of anaesthesia can increase the chance of awareness.

💣Better to give re-bolus with i.v. hypnotic during multiple intubation attempts. Consider using inhalation induction technique. 

💣Beta-blockers,can reduce MAC-Awake and may also decrease the likelihood of PTSD. 

💣We can consider ear plugs or headphones to reduce awareness of noises in the OR. 

💣Nitrous oxide, Ketamine and Opioids suppress cortical arousal during painful stimulation, which may reduce the probability of awareness. But BIS and other EEG monitors do not accurately predict the depth of anesthesia with these drugs. (Because, even though they produce hypnosis, they do not modulate GABA-A receptors and are associated with unchanged or increased high frequency EEG signals.)

💣Propofol, barbiturates, etomidate, and halogenated volatile anesthetic agents all modulate GABA-A receptor activity and shift the cortical EEG to lower frequencies. So, BIS and other EEG-based monitors provide strong correlation with hypnosis for this group of general anesthetics.

💣MAC for N2O & volatile anesthetics is additive (i.e. a mixture of 0.5 MAC N2O plus 0.5 MAC volatile suppresses movement in response to pain like 1 MAC volatile. The HYPNOTIC activities of nitrous oxide and volatile anesthetics are sub-additive. (i.e. a mixture of 0.5 MAC-awake N2O + 0.5 MAC-awake volatile anesthetic is not as hypnotic as 1 MAC-awake volatile. This suggests that N2O has an action which antagonizes the hypnosis induced by volatile anesthetics, perhaps via direct cortical arousal.

💣Many studies say, BIS is not useful in case of dexmedetomidine also; while some others say it will help.

#awareness , #anesthesia , #sedation , #AwarenessAnesthesia , #bis , #AwarenessSurgery 

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Reference:

 CampagnaJA,MillerKW,FormanSA:Mechanismsofactionsof inhaled anesthetics. N Engl J Med 348:2110-2124, 2003

SleighJW,BarnardJP:Entropyisblindtonitrousoxide.Canwesee why? Br J Anaesth 92:159-161, 2004 39. 

ChortkoffBS,BennettHL,EgerEI2nd:Doesnitrousoxideantagonize isoflurane-induced suppression of learning? Anesthesiology 79: 724-732, 1993 40. 

KatohT,IkedaK,BitoH:Doesnitrousoxideantagonizesevofluraneinduced hypnosis? Br J Anaesth 79:465-468, 1997

Update on Bispectral Index monitoring Jay W. Johansen,Best Practice & Research Clinical Anaesthesiology Volume 20, Issue 1, March 2006, Pages 81–99