8/6/2019 Delayed Recovery From Anaesthesia

1/15

8/6/2019 Delayed Recovery From Anaesthesia

2/15

` A conscious individual is awake and aware of their

surroundings and identity.

` The Glasgow Coma Scale though developed for

trauma has remained a reliable means ofassessing consciousness.

` A GCS

8/6/2019 Delayed Recovery From Anaesthesia

3/15

8/6/2019 Delayed Recovery From Anaesthesia

4/15

` The time taken to emerge to full consciousness is

affected by

` Patient factors,

` Anaesthetic factors,` Duration of surgery,

` Painful stimulation

8/6/2019 Delayed Recovery From Anaesthesia

5/15

` There are many different variables affecting drug

metabolism in patients.

` The ideal dose for one patient may not be for

another.

8/6/2019 Delayed Recovery From Anaesthesia

6/15

` Will cause prolonged unconsciousness in elderly

or in overdose but not usually at doses used for

induction or anxiolysis by themselves.

` When administered with other drugs such as highdose opioids.

` Usually metabolised by P450 system.

8/6/2019 Delayed Recovery From Anaesthesia

7/15

` Produce analgesia, sedation and

respiratory depression; the intensity of each action

varies between subjects and can be

difficult to predict.` Dose response also affected by co-administered

drugs.

` Also affected is the response of Carbon Dioxide

receptors in the brainstem with reduced sensitivity.

8/6/2019 Delayed Recovery From Anaesthesia

8/15

` Can mimic prolonged unconsciousness and also

cause hypoventilation.

` Duration of action of these drugs also affected by

a number of other factors.` Patient factors such as plasma cholinesterase

deficiency can also prolong the blockade.

8/6/2019 Delayed Recovery From Anaesthesia

9/15

` Termination of action is by redistribution.

` Also affected by the context sensitive half life

` Emergence usually occurs with 80% reduction in

effect site concentration.` For Example with propofol after a two hour TIVA

infusion emergence takes 36 minutes.

8/6/2019 Delayed Recovery From Anaesthesia

10/15

` Emergence from volatile agent anaesthesia

depends upon pulmonary elimination of the drug

and MAC awake (the end-tidal

concentration associated with eye-opening toverbal command).

` MAC Awake is 30% of the MAC.

` Pulmonary elimination is determined by alveolar

ventilation, bloodgas partition co-efficient anddose (MAC hours)

8/6/2019 Delayed Recovery From Anaesthesia

11/15

` Hypoglycaemia

` Hyperglyceamia.

` Hyponatremia and water excess

` Hyernatremia and dehydration.` Uraemia.

8/6/2019 Delayed Recovery From Anaesthesia

12/15

` Neurological and respiratory changes occur with

decreasing temperature, e.g. confusion (

8/6/2019 Delayed Recovery From Anaesthesia

13/15

` Postoperative respiratory failure causes

hypoxaemia, hypercapnia or both.

` The causes of respiratory failure are multiple

and may be classified into neurological,pulmonary, and muscular.

8/6/2019 Delayed Recovery From Anaesthesia

14/15

` A number of different pathologies can cause

cerebral hypoxic damage resulting in coma.

` Damage may be primary or secondary.

8/6/2019 Delayed Recovery From Anaesthesia

15/15

` There are a number of causes which can cause

prolonged unconsciousness.

` In patients with delayed awakening a stepwise

approach is advisable.