Category Archives: Complications during anesthesia

👁➖BE AWARE OF AWARENESS ➖👁

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💣Premedication 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 (Bi Spectral Index) 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

EXPLICIT AND IMPLICIT AWARENESS DURING ANESTHESIA

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😐(Explicit = Fully and clearly expressed)

😐(Implicit =Implied or understood though not directly expressed)

😐The incidence of awareness is around 0.1–0.2%

😐Explicit Awareness is intentional or conscious recollection of prior experiences as assessed by tests or recall or recognition, which are also called direct memory test.

😐Implicit Awareness is perception without conscious recall. The patient denies recall, but may remember “something” under hypnosis.

😐Awareness (deliberate)

Surgery conducted under local or regional anaesthesia. During some neurosurgical procedures, the patient is woken up to assess whether surgery has affected, or will affect, important areas.

😐STAGES OF AWARENESS ( Griffith and Jones )

1. Conscious perception with explicit memory;

2. Conscious perception without explicit memory;

3. Dreaming;

4. Subconscious perception with implicit memory;

5. No perception and no implicit memory.

😐CAUSES

🔻may result from a failure of the apparatus to deliver adequate concentrations of anesthetic agent. Such failures include leaks, faulty or empty vaporizers, a misconnected or disconnected breathing system, inaccurate pumps, misplaced venous cannula and occluded infusion tubing

🔻failure of the clinician to monitor the concentrations of inspired and expired volatile agents may result in inadequate anesthetic agent being delivered. TIVA is more difficult to monitor in this respect.

🔻may result from an inadequate dosing of the anesthetic agent as represented by the alveolar concentration (it is important to remember that the MAC value that is quoted is only the MAC 50 ) or the computed blood concentration in target-controlled infusion (TCI).

🔻may result from an altered physiology or pharmacodynamics in the patient e.g. Anxiety may increase dose requirements

🔻may result from the wearing off of the induction agent during a difficult intubation sequence or with the anesthetic techniques for rigid bronchoscopy

😐CLINICAL SIGNS

🔻In the spontaneously breathing patient who is not paralyzed, awareness may be manifest by purposeful movement.

🔻Sympathetic stimulation: the main clinical signs are tachycardia, hypertension, diaphoresis and lacrimation; but their absence does not exclude awareness. Attempts have been made to quantify these objectively by using the PRST scoring system (blood Pressure, heart Rate, Sweating, Tear formation)..

😐SEQUELAE:

Commonest is the occurrence of a post-traumatic stress syndrome, whose typical features may include nightmares, insomnia, panic attacks and agoraphobia.

😐CHECKLIST FOLLOWING A COMPLAINT OF AWARENESS DURING GENERAL ANAESTHESIA

1. Visit the patient as soon as possible, along with a witness (Preferably a consultant)

2. Take a full history and document the patient’s exact memory of events

3. Attempt to confirm the validity of the account

4. Keep your own copy of the account

5. Give a full explanation to the patient

6. Offer the patient follow-up, including psychological support, and document that this has been offered

7. Reassure the patient that they can safely have further general anaesthetics, with minimal risk of a further episode of awareness

8. If the cause is not known, try to determine it

9. Notify your medical defence organisation

10. Notify your hospital administration

11. Notify the patient’s GP
#awareness , #ptsd , #AnesthesiaComplications , #TheLayMedicalMan , From http://www.facebook.com/drunnikrishnanz , partial reference from frca.uk , #anaesthesia