This document discusses inhalational anesthetics, including their properties, mechanisms of action, examples of agents, and factors that influence their potency and effects. It defines minimum alveolar concentration as the concentration needed to prevent movement in 50% of subjects in response to pain. Several volatile anesthetic agents are mentioned, such as halothane, isoflurane, desflurane, and sevoflurane, along with their characteristics and side effect profiles. Nitrous oxide is discussed as a gaseous anesthetic often used in combination with other agents.

2. INHALATIONAL ANESTHETIC
• CHEMICAL HAVING GENERAL ANESTHETIC PROPERTIES WHICH CAN
BE DELIVERED VIA INHALATION.
• ADMINISTERED THROUGH
TRACHEAL TUBE
LARYNGEAL MASK AIRWAY
FACE MASK

3. MAC MINIMUM ALVEOLAR
CONCENTRATION
• Volume Of Vapor In Alveoli To Prevent Movement In 50% Of Subjects
In Response To Pain
• Used To Compare Strength Or Potency Of Anesthetic Vapor Lower
Mac More Potent Volatile Anesthetic
• Concept Of Mac Given In 1965
• Mac Of Volatile Substance Is Inversely Proportional To Its Lipid
Solubilty , Meyer Overton Hypothesis

4. FACTORS AFFECTING MAC

5. MAC VALUES

6. BLOOD GAS PARTITION COEFFICIENT
• Ratio Of Concentration
Of Gas In Each Of Two
Phases Of Matter At
Steady State
• Lower The Coefficient
Less Soluble Anesthetic
Is In Blood
• Known As Ostwald
Coefficient

7. OIL GAS COEFFICIENT

8. VOLATILE ANESTHETIC AGENTS
• THEY ARE EMITTED AS GASES FROM CERTAIN SOLIDS OR LIQUIDS
• LIQUID AT ROOM TEMPERATURE
• REQUIRE USE OF VAPORIZERS FOR INHALATION
HALOTHANE
DESFLURANE
ISOFLURANE
SEVOFLURANE

9. ANESTHETIC GASES
• NITROUS OXIDE(LAUGHING GAS)
• COLORLESS , NON FLAMMABLE GAS
• LAUGHING GAS EFFECT COINED BY HUMPHREY DAVID
• USED AS A DISSOCIATIVE ANESTHETIC
• USED WITH OXYGEN AS MIXTURE IN RATIO 2:1
• WEAK GENERAL ANESTHETIC USED ALONG WITH OTHER POWERFUL
GENERAL ANESTHETIC
• MAC 105% BLOOD/GAS PARTITION COFFICIENT 0.46
• USED TO RELIEVE PAIN ASSOCIATED WITH LABOR, SURGERY ETC

10. ENTONOX
• GAS MIXTURE OF HALF OXYGEN AND
HALF NITROUS OXIDE USED FOR
PAIN RELIEF
• USED DURING LABOR, TRAUMA ,
PALLIATIVE CARE
• EFFECT STARTS IN 30 SECONDS AND
ENDS ABOUT A MINUTE
• NOT FOR PEOPLE WITH
PNEUMOTHORAX OR BOWEL
OBSTRUCTION

11. ENTONOX

12. ENTONOX
• IT IS MADE VIA POYNTING EFFECT
• GASEOUS OXYGEN IS BUBBLED THROUGH LIQUID NITROGEN FORING
GASEOUS MIXTURE OF BOTH
• SEPERATES AT LOW TEMPERATURE <4 DEGREE C THUS CYLINDER IS
SHAKEN BY INVERTING IT
• CYLINDER WITH SCHRADER VALVE ATTACHMENT USAble ONLY ON
DEMAND BASED SETS

13. XENON
• DISCOVERED IN 1898 BY WILLIAM RAMSAY
• MAC VALUE 63.1 %
• BLOOD GAS PARTITION COEFFICIENT 0.14
• COLORLESS ODOURLESS GAS
• LOW BLOOD SOLUBILTY
• LEAST SIDE EFFECTS FASTER RECOVERY

14. VOLATILE
INHALATIONAL
ANESTHETICS

15. HALOTHANE
• ALSO KNOWN AS FLUTHANE
• USED TO INDUCE OR MAINTAIN ANESTHESIA
• DOES NOT INCREASE PRODUCTION OF SALIVA THUS VERY USEFUL
FOR PATIENTS WITH DIFFICULT INTUBATION
• METABOLIZED BY HEPATIC CIRCULATION
• EXCRETED BY KIDNEY AND RESPIRATORY WAYS
• SIDE EFFECTS ARRYTHMIAS , RESPIRATORY DEPRESSION ,
HEPATOTOXICITY
• NOT TO BE USED IN PEOPLE WITH HISTORY OF MALIGNANT
HYPERTHERMIA

16. HALOTHANE
• DISCOVERED IN 1955
• MAC 0.74%
• BLOOD GAS PARTITION COEFFICENT
2.4
• VAPOR PRESSURE 244 mmhg
• Sweet CHLOFORM LIKE ODOR

17. ISOFLURANE
• ALSO KNOWN AS FLORANE
• CAN IRRITATE AIRWAY THUS OTHER MEDICIN
NEEDED BEFORE GIVING IT
• SIDE EFFECTS HYPOTENSION, HYPERKALEMIA
• PUNGENT GAS
• USED AS MAINTENANCE AGENT
• NOT TO BE USED IN HYPOVOLEMIC PATIENTS
CAN GIVE IRRITBLE AND TOXIC FUMES IF
EXPOSED TO FLAME

18. DESFLURANE
• USED FOR MAINTENACE OF GENERAL ANESTHESIA
• COSTLY
• RAPID ONSET OF ACTION
• KNOWN AS SUPRANE
• CAN CAUSE TACHYCARDIA
• VAPOR PRESSURE 672 mmhg
• MAC 6
• BRONCHODILATOR
• HIGH RISK OF LARYNGOSPASM IN PAEDIATRIC PATIENTS

19. ENFLURANE
• FORMULATED BY ROSS TERRELL IN 1963
• NOT USED NOWDAYS COMMONLY
• MAC 1.68
• VAPOR PRESSURE 172 mmhg
• DECREASED MYOCARDIAL CONTACTIBILTY
• KNOWN AS ENTHRANE
• INCREASE ICP
• INCREASEED CHANCES OF HAVING SEIZURES

20. SEVOFLURANE
• SEVORANE
• 2ND FASTEST ACTING INHALATIONAL AGENT
• METABOLISED BY LIVER
• MAY ACCELERATE ALZHEIMR
• LESS IRRITATES MUCOUS MEMBRANES

21. METHOXYFLURANE
• KNOWN AS PENTHROX
• USED MAINLY TO REDUCE TRAUMA RELATED PAIN
• CAN CAUSE NEPHROTOXICITY
• MAC 0.16%

22. VAPOR PRESSURE

23. KEY POINTS
• FASTEST ACTING INHALATIONAL AGENT – DESFLURANE
SEVOFLURANE
• INDEX OF POTENCY OF GENERAL ANESTHESIA – MAC
• LIPID SOLUBILTY OF INHALATIONAL AGENT BY – OIL GAS PARTITION
COEFFICIENT
 PUNGENT VOLATILE ANESTHETIC – ISOFLURANE DESFLURANE
 SODALIME SHOULD NOT BE USED WITH SEVOFLURANE AND TRILENE
AS IT CAN FORM NEUROTOXIC GAS
 LEAST ANALGESIC PROPERT - HALOTHANEE

24. KEY POINTS
• EPILEPTOGENIC –
ENFLURANE ,
SEVOFLURANE
• LOWER MAC HIGHEST
POTENCY