Anesthesia Flashcards
American Society of Anesthesiologists’ Classification System
- A normal healthy patient
- A patient with mild systemic disease
- A patient with severe systemic disease
- A patient with severe systemic disease that is a constant threat to life
- A moribund patient who is not expected to survive without the operation
- A declared brain-dead patient whose organs are being removed for donor purposes
Barbiturates
Are central nervous system depressants. Examples include thiopental sodium, sodium methohexital, thiamylal, and Nembutal. They are excellent anesthetics and amnestics with a short onset and duration of action
Benzodiazepines
Increase receptor availability for the inhibitory neurotransmitter gamma-aminobutyric acid. They have a longer time to onset but have a longer duration than barbiturates. They are excellent amnestics, but provide no analgesia.
Examples include midazolam, diazepam, and lorazepam.
Narcotics
Bind to opioid receptors, thus interfering with the transmission of pain messages to the brain. They also have a depressant action that decreases the perception of pain.
Examples include morphine, fentanyl, hydromorphone (Dilaudid), sufentanil, and remifentanil.
They are excellent analgesics, but adverse effects include respiratory depression.
Propofol
Sometimes referred to as “milk of anesthesia” because of its white color, is a hypnotic agent. It has a fast onset of action. The effects wear off quickly when the drug is discontinued. The patient is awake and clear more quickly than with other sedatives. It is a good amnestic but provides no analgesia. For this reason, it is typically used in conjunction with analgesics.
Ketamine
A phencyclidine hydrochloride (PCP) derivative. It causes a dissociative state, which means the patient appears to be “dissociated” from the external environment but not necessarily asleep. Patients may experience hallucinations, so it is generally used in conjunction with amnestics for sedation.
It is an excellent analgesic and sedative.
Etomidate
A sedative-hypnotic, causes the least detrimental cardiovascular changes of all nonopioid induction drugs. It may be used as an alternative to ketamine for induction in hypovolemic patients.
Malignant hyperthermia
A hypermetabolic state that can be caused by exposure to a triggering agent such as a volatile gas anesthetic (except nitrous oxide) and/or succinylcholine. The triggering agent causes sustained muscular contractions related to an increase in intracellular calcium ion concentration. The sustained contractions result in signs of hypermetabolism. These include acidosis, tachycardia, hypercarbia, glycolysis, hypoxemia, and hyperthermia.
The most specific sign of MH is skeletal muscle rigidity. However, the first sign noted by the anesthesia or nursing staff is an unexplained tachycardia. Hyperthermia, the classic sign of MH, is usually a late sign.
Malignant hyperthermia is a genetic disorder.
Malignant hyperthermia is a medical emergency. Without quick and appropriate treatment, the patient will die. It is treated with dantrolene, a muscle relaxant that depresses the coupling mechanism in skeletal muscles. Important nursing interventions include administering dantrolene and cooling the patient.*
Amides
- Lidocaine has a rapid onset and a short to intermediate duration of 60 to 120 minutes. The maximum dose is 4.5 mg/kg (30 mL in an average 70-kg adult). It has excellent spreading ability and is the main local anesthetic.
- Bupivacaine has a slow onset and a long duration of 4 to 8 hours. The maximum dose is 2 mg/kg (50 mL in an average 70-kg adult). It provides excellent postoperative analgesia.
Both drugs may be mixed with epinephrine for its vasoconstrictive effects to help control bleeding at the procedure site. It also prolongs the action of the drugs.
Esters
• Cocaine has a slow onset and medium duration. It is used in nasal surgery more for its vasoconstrictive effects than as an analgesic. It can cause hypertension and tachycardia as a result of increased catecholamine release.
