Guedel's classification

Guedel's classification is a means of assessing of depth of general anesthesia introduced by Arthur Ernest Guedel (1883-1956) in 1937.

History

Further information: History of general anesthesia

Since general anesthesia first became widely used in late 1846, assessment of anesthetic depth was a problem. To determine the depth of anesthesia, the anesthetist relies on a series of physical signs of the patient. In 1847, John Snow (1813-1858)^[1] and Francis Plomley^[2] attempted to describe various stages of general anesthesia, but Guedel in 1937 described a detailed system which was generally accepted.^[3]^[4]^[5]

This classification was designed for use of a sole inhalational anesthetic agent, diethyl ether (commonly referred to as simply "ether"), in patients who were usually premedicated with morphine and atropine. At that time, intravenous anesthetic agents were not yet in common use, and neuromuscular-blocking drugs were not used at all during general anesthesia. The introduction of neuromuscular blocking agents (such as succinylcholine and tubocurarine) changed the concept of general anesthesia as it could produce temporary paralysis (a desired feature for surgery) without deep anesthesia. Most of the signs of Guedel's classification depend upon the muscular movements (including respiratory muscles), and paralyzed patients' traditional clinical signs were no longer detectable when such drugs were used.^[6] Since 1982, ether is not used in United States.^[7] Now, because of the use of intravenous induction agents with muscle relaxants and discontinuation of ether, Guedel’s classification is regarded as obsolete. Depth of general anesthesia can now be estimated using devices such as the BIS monitor,^[5] however, the use of BIS monitoring remains controversial.^[8]

Stages of Anesthesia

Stage I (stage of analgesia or disorientation): from beginning of induction of general anesthesia to loss of consciousness.

Stage II (stage of excitement or delirium): from loss of consciousness to onset of automatic breathing. Eyelash reflex disappear but other reflexes remain intact and coughing, vomiting and struggling may occur; respiration can be irregular with breath-holding.

Stage III (stage of surgical anesthesia): from onset of automatic respiration to respiratory paralysis. It is divided into four planes:

Plane I - from onset of automatic respiration to cessation of eyeball movements. Eyelid reflex is lost, swallowing reflex disappears, marked eyeball movement may occur but conjunctival reflex is lost at the bottom of the plane
Plane II - from cessation of eyeball movements to beginning of paralysis of intercostal muscles. Laryngeal reflex is lost although inflammation of the upper respiratory tract increases reflex irritability, corneal reflex disappears, secretion of tears increases (a useful sign of light anesthesia), respiration is automatic and regular, movement and deep breathing as a response to skin stimulation disappears.
Plane III - from beginning to completion of intercostal muscle paralysis. Diaphragmatic respiration persists but there is progressive intercostal paralysis, pupils dilated and light reflex is abolished. The laryngeal reflex lost in plane II can still be initiated by painful stimuli arising from the dilatation of anus or cervix. This was the desired plane for surgery when muscle relaxants were not used.
Plane IV - from complete intercostal paralysis to diaphragmatic paralysis (apnea).

Stage IV: from stoppage of respiration till death. Anesthetic overdose cause medullary paralysis with respiratory arrest and vasomotor collapse. Pupils are widely dilated and muscles are relaxed.

In 1954, Joseph F. Artusio further divided the first stage in Guedel's classification into three planes.^[9]

1st plane The patient does not experience amnesia or analgesia
2nd plane The patient is completely amnesic but experiences only partial analgesia
3rd plane The patient has complete analgesia and amnesia

References

↑ John Snow and Meyer Joubert. Five stages of narcotism; On the inhalation of ether in surgical operation, London, 1847
↑ Plomley F. Lancet 1847,p. 134 (reprinted in classical file, Survey of Anesthesiology 1970, 14, 88)
↑ Lunn, J.N. (1982) Lecture Notes on Anaesthetics, 2nd edn. Blackwell Scientific Publications, Oxford.
↑ Guedel AE. Inhalation anesthesia, Ed 2, New York, 1951, Macmillan
1 2 Bhargava AK, Setlur R, Sreevastava D. (Jan 2004). "Correlation of bispectral index and Guedel's stages of ether anesthesia". Anesth Analg. 98 (1): 132–4. PMID 14693605.
↑ Laycock, J. D. (1953). "Signs and stages of anaesthesia; a restatement". Anaesthesia. 8 (1): 15–20. doi:10.1111/j.1365-2044.1953.tb12284.x. PMID 13008025.
↑ Carlsson C, Karlsson JP, Daniels FB, Harwick RD. The end of ether anesthesia in the USA. In: Fink BR, Morris LE, Stephen CR, eds. Proceedings 3rd International Symposium on the history of Anesthesia. Atlanta, Georgia. Wood Library - Museum of anesthesiology, Illinois. 1992: 100–2.
↑ McCulloch, T. J. (2005). "Use of BIS Monitoring Was Not Associated with a Reduced Incidence of Awareness". Anesthesia & Analgesia. 100 (4): 1221. doi:10.1213/01.ANE.0000149022.48021.24.
↑ Artusio JF. Di-ethyl ether analgesia: a detailed description of the first stage of ether analgesia in man. J Pharmacol Exp Ther 1954, 111, 343-334

Anesthesia (outline)

Types	General Sedation Twilight anesthesia Local Topical Intercostal nerve block Neuraxial blockade Spinal Epidural Dental Inferior alveolar nerve

Techniques	Airway management Anesthesia provision in the US Arterial catheter Bronchoscopy Capnography Dogliotti's principle Drug-induced amnesia Intraoperative neurophysiological monitoring Nerve block Penthrox inhaler Tracheal intubation

Scientific Principles	Blood–gas partition coefficient Concentration effect Fink effect Minimum alveolar concentration Second gas effect

Measurements	ASA physical status classification system Baricity Bispectral index Direct Fick method Entropy monitoring Fick principle Goldman index Guedel's classification Mallampati score Neuromuscular monitoring Thyromental distance

Instruments	Anaesthetic machine Anesthesia cart Boyle's machine Gas cylinder Laryngeal mask airway Laryngeal tube Medical monitor Odom's indicator Relative analgesia machine Vaporiser Double-lumen endotracheal tube Endobronchial blocker

Complications	Emergence delirium Allergic reactions Anesthesia awareness Local anesthetic toxicity Malignant hyperthermia Perioperative mortality Postanesthetic shivering Postoperative nausea and vomiting Postoperative residual curarization

Fields of study	Cardiothoracic Geriatric Oral sedation dentistry

Professions	Anesthesiologist Anesthesiologist assistant Nurse anesthetist Operating Department Practitioners Certified Anesthesia Technician Certified Anesthesia Technologist Anaesthetic technician

History	A.C.E. mixture Helsinki Declaration for Patient Safety in Anaesthesiology History of general anesthesia History of neuraxial anesthesia History of tracheal intubation

Organizations	American Association of Nurse Anesthetists American Society of Anesthesia Technologists & Technicians American Society of Anesthesiologists Anaesthesia Trauma and Critical Care Association of Anaesthetists of Great Britain and Ireland Association of Veterinary Anaesthetists Australian and New Zealand College of Anaesthetists Australian Society of Anaesthetists International Anesthesia Research Society

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Guedel's classification

History

Stages of Anesthesia

See also

References