This document discusses Guedel's criteria for determining the depth of anesthesia. It describes the four stages and planes of anesthesia: stage 1 involves a dream-like state with normal reflexes; stage 2 involves irregular breathing and increased heart rate and blood pressure; stage 3 involves regular breathing divided into four planes involving eye and reflex changes and pupil dilation; stage 4 involves respiratory and circulatory failure leading to death if not addressed. Guedel's criteria are based on respiration, eye movements, reflexes, and other responses and provide guidance for assessing anesthesia depth during induction and recovery.

2. Presented By :
Dr Farooque Siddiqui
Oral & Maxillofacial Resident

3. In administering an anesthesia
Signpost
Guides in determination of depth of anesthesia
 Guedel describe depth of anaesthesia by dividing it
into stages and planes.

4.  Guedel’s criteria based on :
 Respiration
 Eyeball movement
 Presence or absence of various reflexes
 Gillespie added other criteria
 Secretion of tears
 Response to skin incision
 Evaluation of pharyngeal &
laryngeal reflexes

5.  Stages were first described for ether anesthesia
 Can be used with modification for all agents
 Can be recognized during both induction & recovery

7.  Starts from beginning of anaesthetic inhalation and
lasts up to the loss of consciousness.
 Pain is progressively abolished.
 Patient remains conscious, can hear and see, and feels
a dream like state

8.  Reflexes and respiration remain normal.
 Some minor operations can be carried out during this
stage
 But it is difficult to maintain
 Therefore use is limited to short procedures

9.  Stage starts from loss of consciousness upto gain of
rhythmical respiration
 Respiration – Irregular and large in volume
 Heart rate and BP raises
 Pupils – Large and divergent
 Muscle tone increased – jaw may be tight
 Patient may shout or struggle
 Involuntary micturation , or defecation

11.  Extends from onset of regular respiration to cessation of
spontaneous breathing.
 This has been divided into 4 planes:
o Plane 1- Roving eyeballs.
o This plane ends when eyes become fixed.
o Plane 2- Loss of corneal and laryngeal reflexes.
o Plane 3- Pupil starts dilating and light reflex is lost.
o Plane 4- Intercostal paralysis
Shallow abdominal respiration
Dilated pupil.

12.  As anaesthesia passes to deeper planes
 Progressively-muscle tone decreases
 BP falls
 Heart Rate increases with weak pulse
 Respiration decreases in depth and later in frequency

13.  There is cessation of breathing leading to failure of
circulation and death.
 Pupil is widely dilated
 Muscles are totally flabby
 Pulse is thready or imperceptible
 BP is very low.