Stages of General Anesthesia

 Clinical Notes

• Stage I is often brief due to rapid induction agents.

• Stage II is avoided or minimized with modern anesthetics to reduce risk of complications like laryngospasm.

• Stage III is carefully maintained during surgery.

• Stage IV is considered an overdose and must be prevented.

• Stage III Plane 3 → Surgical anaesthesia
• Most reliable indicator: Regular respiration

 Isoflurane

• Agent of choice in Cardiac patients.
•  Vasodilation with least cardiovascular depression.
•  Intracranial pressure (moderate increase).
• Not ideal for asthmatics compared to Sevoflurane.

Desflurane

•  Fastest induction & recovery.
•  Minimally metabolized.
• Preferred in shock & renal failure.

Sevoflurane

•  Induction agent in children.
• Maximum bronchodilation (non-asthmatics).
• More cardiodepressant than Isoflurane.

Ether

• Highly explosive  (not used today).
• Classic: Complete anaesthetic agent.
• Causes max emesis.
• Basis of anaesthesia staging (Guedel’s classification).

• Used for: Airway maintenance
• ❌ Contraindicated in gastric regurgitation risk
• “Brain mask” = LMA

Emergency Drugs for Sedated Patients (AAPD Guidelines)

In the context of pediatric dentistry and sedation, it is crucial to be prepared for potential emergencies that may arise during or after sedation. The following is a list of emergency drugs that may be needed to rescue a sedated patient, along with their indications and uses.

Emergency Drugs

1. Albuterol for Inhalation

   • Indication: Bronchospasm or asthma exacerbation.
   • Use: Administered via nebulizer or metered-dose inhaler to relieve bronchospasm.

2. Ammonia Spirits

   • Indication: Syncope or fainting.
   • Use: Inhaled to stimulate respiration and increase alertness.

3. Atropine

   • Indication: Bradycardia or asystole.
   • Use: Increases heart rate by blocking vagal effects on the heart.

4. Diazepam

   • Indication: Seizures or severe anxiety.
   • Use: Administered intravenously or intramuscularly for rapid sedation or seizure control.

5. Diphenhydramine

   • Indication: Allergic reactions or anaphylaxis.
   • Use: Antihistamine for allergic symptoms; may also be used for sedation.

6. Epinephrine (1:1,000 and 1:10,000)

   • Indication: Anaphylaxis or severe asthma attack.
   • Use: 1:1,000 for intramuscular injection; 1:10,000 for intravenous administration in cardiac arrest.

7. Flumazenil

   • Indication: Benzodiazepine overdose.
   • Use: Reversal agent for sedation caused by benzodiazepines.

8. Fosphenytoin

   • Indication: Status epilepticus.
   • Use: Anticonvulsant for seizure control, administered intravenously.

9. Glucose (25% or 50%)

   • Indication: Hypoglycemia.
   • Use: Administered intravenously to rapidly increase blood glucose levels.

10. Lidocaine

    • Indication: Cardiac arrhythmias or local anesthesia.
    • Use: Antiarrhythmic agent for ventricular arrhythmias; also used for local anesthesia.

11. Lorazepam

    • Indication: Anxiety or seizures.
    • Use: Sedative and anticonvulsant, administered intravenously or intramuscularly.

12. Methylprednisolone

    • Indication: Severe allergic reactions or inflammation.
    • Use: Corticosteroid for reducing inflammation and managing allergic reactions.

13. Naloxone

    • Indication: Opioid overdose.
    • Use: Opioid antagonist to reverse respiratory depression and sedation caused by opioids.

14. Oxygen

    • Indication: Hypoxia or respiratory distress.
    • Use: Administered to improve oxygen saturation and support respiratory function.

15. Racemic Epinephrine

    • Indication: Croup or severe bronchospasm.
    • Use: Administered via nebulization to reduce airway swelling and improve breathing.

16. Rocuronium

    • Indication: Neuromuscular blockade for intubation.
    • Use: Non-depolarizing neuromuscular blocker for facilitating intubation.

17. Sodium Bicarbonate

    • Indication: Metabolic acidosis or hyperkalemia.
    • Use: Administered intravenously to correct acidosis and manage elevated potassium levels.

18. Succinylcholine

    • Indication: Rapid sequence intubation.
    • Use: Depolarizing neuromuscular blocker for quick intubation.

• Ether → Basis of anaesthesia staging
• MAC (Minimal Alveolar Concentration) → Indicator of potency
• Minimum O₂ in mix → 25%
• Agents fluorinated → 🔥 Non-inflammable