Types of agents used for general anesthesia

Types of agents used for general anesthesia

A. IV induction agents or total intravenous anesthesia "TIVA" has rapid onset & last only few mins.

This allows time for endo-tracheal tube to be inserted & inhalation agent to be started

1. Clients with a history of malignant hyperthermia should avoid inhalation agents because

they trigger MH (malignant hyperthermia)

2. Examples of IV agents:

Barbituates: pentothal & brevital

Non-barbituates: amidate & diprivan

B. Inhalation agents – may be volatile liquids – room temp = gas

1. Volatile liquids are administered through a specially designed vaporizer after being mixed

with O₂ as a carrier gas

2. enters body through alveoli

3. administered through a mask, endotracheal tube, laryngeal mask airway or tracheostomy

4. Ease of administration & rapid excretion by ventilation make them desirable agenst

5. Non-desirable effect is the irritating effect on respiratory tract

6. Complications that can arise are coughing, laryngospasm, bronchospasm, ↑secretions,

and respiratory depression

7. Examples of volatile liquids: fluothane, ethrane, & forane

8. gaseous agents: nitrous oxide

C. Adjuncts to general anesthesia – drugs that are added to an inhalation anesthetic other than IV

induction agent is an adjunct

1. Opioids are used preoperatively for sedation & analgesia, intraoperatively for induction &

maintenance of anesthesia, & postop for pain management.

a. They alter response to pain stimuli

b. If given close to the end of surgery, the residual analgesia often carries over in the PACU

This allows pt to awaken pain-free.

c. Examples: fentanyl, morphine-sulfate, & demerol

d. increase risk of respiratory depression – closely observe pt respiration & O₂ sat

e. Narcan is the drug used to reverse respiratory depression from opiates & it will reverse all

analgesic effects

2. Benzodiazepines are widely used for pre-medication before surgery for their amnestic effects, as

agents for the induction & maintenance of anesthesia, for conscious sedation, as supplemental

IV sedation during local & regional anesthesia, & for postop anxiety & agitation

a. Versed is the most commonly used benzo due to its shorter duration of aciton, amnestic

property, & absence of pain on injection

b. can be given IM or IV

c. can get respiratory depression with benzos

d. Flumazenil (romazicon) is the antagonist that may be used to reverse effects of benzos

(used as an antidote like narcan)

3. Neuromuscular blocking agents (muscle relaxants) are used as adjuncts to general anesthesia

to facilitate endotracheal intubations & to optimize the surgical working conditions by providing

relaxation & paralysis of skeletal muscles

a. neuromuscular blocking agents interrupt the trans. of nerve impulses at neuromuscular. jxn.

b. disadvantages of use of muscle relaxants is that the duration of their action may be longer

than the surgical procedure or reversal agents may not be completely effective & eliminated -

residual effects

Pt must be carefully observed so that their respiratory muscle movements & air patency good

Are they getting enough oxygen?

4. Antiemetics are used preoperatively, intraop, & postop. can be given with anesthesia

examples:

a. Zofran

b. phenergen

c. reglan

d. anapsin