1. 19
Anesthetic Agents

2. Ideal Anesthetic
Rapid and pleasant induction and withdrawal from anesthesia
Skeletal muscle relaxation
Analgesia
High potency
Wide therapeutic index
Nonflammable
Chemical inertness

3. Stages of Anesthesia
Analgesia: pain abolished but consciousness retained
Excitement: unconsciousness but possible unpleasant shaking, violence, and fear

4. Stages of Anesthesia
Surgical anesthesia: progressive muscle relaxation and unconsciousness
Medullary paralysis: respiratory failure and circulatory collapse

5. Preoperative Medications
Adjuncts to surgery; preanesthetics
Used to reduce anxiety, sedate, produce amnesia, increase comfort, reduce gastric acidity and volume, increase gastric emptying, decrease nausea and vomiting, reduce incidence of aspiration

6. Table 19-1 Preoperative Medications as Adjuncts to Surgery

7. Table 19-1 (continued) Preoperative Medications as Adjuncts to Surgery

8. Table 19-1 (continued) Preoperative Medications as Adjuncts to Surgery

9. General Anesthetics
Affect whole body; produce unconsciousness by depressing CNS
Skeletal muscle relaxation and diminished reflexes
Used in combinations to smoothly and rapidly induce anesthesia and allow prompt recovery; ensure wide safety margin; and reduce side effects

10. Choosing Appropriate Anesthesia
The choice of anesthetic drug depends on many factors, including:
Patient’s general physical condition
Area being operated on
Anticipated length of procedure

11. Adverse Drug Reactions
Older adults are more likely to experience adverse drug reactions than younger adults because, in general, they take more medications.

12. Types of General Anesthesia
Inhalation anesthetics: volatile liquids or gases
Intravenous anesthetics

13. Table 19-2 General Anesthetics Used by Inhalation

14. Dangers of Malignant Hyperthermia
Malignant hyperthermia is a life-threatening, acute pharmacogenetic disorder that develops during anesthesia.
Characterized by rapid increase in body temperature, unexplained tachycardia, unstable blood pressure, muscle rigidity, and cyanosis

15. Table 19-3 General Anesthetics Commonly Given by Injection

16. Figure 19-1A Mechanism of action of anesthetics: normal nerve conduction.

17. Figure 19-1B Mechanism of action of anesthetics: anesthetic blocking sodium channels.

18. Diabetes and Surgery
The stress of surgery in diabetic patients may increase blood glucose levels.
Insulin or hypoglycemic medications should be coordinated with the:
Patient
Surgeon
Anesthesiologist

19. General Anesthetics: Uses
Lipophilic agents that cross blood–brain barrier to close sodium channels to prevent neural conduction
Used in combination to produce balanced anesthesia

20. General Anesthetics: Adverse Effects
Common: drowsiness, weakness, or fatigue for a few days postanesthesia; fuzzy thinking, blurred vision, incoordination
Other: headache, shivering, muscle pain, nausea and vomiting, sore throat, nightmares

21. General Anesthesia: Contraindications
Contraindicated in patients who:
Have received MAOIs in previous 14 days
Are intolerant to benzodiazepines

22. General Anesthesia: Contraindications
Also contraindicated in patients who have:
Hypersensitivity
Myasthenia gravis
Acute glaucoma
Increased intracranial pressure

23. General Anesthesia: Contraindications
Also contraindicated in patients who have:
Impaired cerebral circulation
Alcohol intoxication
Status asthmaticus
Porphyrias

24. Local Anesthetics
Used to provide regional or topical anesthesia without loss of consciousness
Two groups: esters and amides

25. Table 19-4 Local Anesthetics

26. Table 19-4 (continued) Local Anesthetics

27. Amide Anesthetics: Uses
Inhibit sodium channels, which inhibits nerve impulse transmission
Used to increase patient comfort and cooperation during procedures including incision and drainage, laceration repair, biopsy, wart treatment, vasectomy, neonatal circumcision, dental procedures, childbirth, diagnostic procedures

28. Amide Anesthetics: Adverse Effects
Toxic effects are dose related.
Symptoms of toxicity: dizziness, nystagmus, restlessness, disorientation, psychosis, slurred speech, tremors, hypotension, bradycardia, cardiac arrest

29. Amide Anesthetics: Contraindications
Contraindicated in older adults, debilitated adults, and children; pregnancy, labor, lactation, sepsis, acidosis, heart or spinal block, severe hemorrhage, hypotension and shock, hypertension, and more
Local anesthetics interact with many drugs.

30. Amide Anesthetics: Patient Information
Instruct patients to report
Dizziness
Disorientation
Slurred speech

31. Mechanism of Action of Lidocaine Animation
Click on the screenshot to view an animation showing the mechanism of action of lidocaine.
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32. Specific Anesthetic Applications
Topical anesthesia
Infiltration anesthesia
Field block anesthesia
Nerve block anesthesia
Spinal anesthesia
Epidural anesthesia

33. Figure Techniques for applying local anesthesia: topical (A), nerve block (B), infiltration (C), spinal (D), and epidural (E).

34. Topical Anesthesia
Application of nerve conduction blocking agent onto tissue layer
Provides anesthesia of urethra, vagina, rectum, skin
Affected tissue is limited to area in contact with topical anesthesia.
Cryoanesthesia: application of freezing agent

35. Local Infiltration Anesthesia
Blocks nerves
Produced by injection of anesthetic into an area
Most common local anesthesia

36. Field Block Anesthesia
Affects a single nerve, deep plexus, or network of nerves
Administered in series of injections to form a wall of anesthesia around an operative field

37. Spinal Anesthesia
Anesthetic agent is injected into subarachnoid space through a spinal needle
Used for gynecological, obstetrical, orthopedic, and genitourinary surgery

38. Epidural Anesthesia
Injection of local anesthetic into epidural space via a catheter; allows repeated infusions
Anesthetic agent is slowly absorbed into cerebrospinal fluid.
Used for labor and delivery