1. ANESTHESIA Claro M. Isidro md

2. Anesthesia

Loss of consciousness

Analgesia

Adequate muscle relaxation

Analgesia

Loss of sensation to pain

3. Types of Anesthetics :

General Anesthetics

• Reversible loss of consciousness

• Loss of CNS activity

Local Anesthetics

• No loss of consciousness

• Reversible loss of pain sensation

4. GENERAL ANESTHETICS:

INHALATIONAL ANESTHETICS

INTRAVENOUS ANESTHETICS

5. STAGES OF GENERAL ANESTHESIA (Guedel)

Stage I: Analgesia

Stage II: Excitement/ Delirium

Stage III: Surgical Anesthesia

• Plane I: reg. breathingloss of eyemovement

• Plane II initiation of IC muscle paralysis

• Plane III:completion ICM paralysis

• Plane IV:diaphragmatic paralysis

Stage IV: Medullary Paralysis

6.

Pharmacokinetics:

tension (partial pressure) in the braindepth

tension in this tissuesrate of induction and recovery

Flow of anesthetic during induction:

AnesthesiaLungsArterialBrain &

machineblood tissues

GENERAL ANESTHETICS: 7.

Pharmacokinetics:

absorption (uptake)

distribution

metabolism

eliminationlungs

Principal objective:

To achieve a constant and optimal brain partial pressure of the inhaled anesthetic

GENERAL ANESTHETICS: 8.

2 PHASES:

• • • Pulmonary Phase

• • • Circulatory Phase

GENERAL ANESTHETICS: UPTAKE 9.

Pulmonary Phase

• • Concentration of the anestheticagent in the inspired gas

• • Pulmonary ventilation

• • Transfer ofanesthetic gasesfrom alveoli to blood

• • • solubility of the agent

• • • rate of pulmonary blood flow

• • • partial pressure in the alveoli andmixed venous blood

GENERAL ANESTHETICS: UPTAKE 10. GENERAL ANESTHETICS: SOLUBILITY Partition Coefficient Blood:Gas Brain:Blood Soluble Methoxyflurane 12 2 Intermediate Halothane 2.4 1.9 Enflurane 1.9 1.5 Isoflurane 1.4 1.6 Poorly soluble Nitrous Oxide 0.46 1.1 Desflurane 0.42 1.3 Sevoflurane 0.59 1.7 11.

As a rule, the more soluble an anesthetic in the blood the more of it must be dissolved to raise the partial pressure.

12.

Pulmonary Phase

• • Concentration of the anestheticagent in the inspired gas

• • Pulmonary ventilation

• • Transfer ofanesthetic gasesfrom alveoli to blood

• • • solubility of the agent

• • • rate of pulmonary blood flow

• • • partial pressure in the alveoli andmixed venous blood

GENERAL ANESTHETICS: UPTAKE 13. GENERAL ANESTHETICS: UPTAKE

Circulatory or Distribution Phase

• • Solubility

• • • tissue:blood solubility coefficient

• • Tissue Blood Flow

• • • • Vessel-Rich group 75% of CO

• • • • Muscle Group 3%

• • • • Fatty Group 2%

• • • • Vessel-Poor group -