General Anesthetics Flashcards
What are the types of inhaled anesthetics?
Gases:
- N2O
Volatile halogenated hydrocarbons
- Desflurane
- Sevoflurane
- Enflurane
- Isoflurane
- Halothane
- Methoxyflurane
What are the types of IV anesthetics?
- Barbiturates
- Propofol
- Ketamine
- Etomidate
What are the common features of inhaled anesthetics?
- Increased perfusion of brain
- Cause bronchodilation
- Decrease minute ventilation
- Potency correlates with liposolubility
- Rate of onset inversely correlates to blood solubility
- Recovery is due to redistribution from the brain
Inhaled anesthetics MOA?
- Positive modulation of GABAA and glycine receptors
- Inhibition of nicotinic receptors
What is Minimum Alveolar Concentration (MAC)?
- MAC is concentration that results in immobility in 50% of pts when exposed to a noxious stimulus such as surgical incision
- MAC%; lambda (oil:gas); lambda (blood:gas)
- Nitrous Oxide: 104; 1.4; 0.47
- Desflurane: 6; 19; 0.45
- Sevoflurane: 2; 51; 0.65
- Enflurane: 1.7; 98; 1.8
- Isoflurane: 1.4; 98; 1.4
- Halothane: 0.75; 224; 2.3
- Methoxyflurane: 0.16; 960; 12
Which inhaled anesthetics reduce MAP mainly by myocardial depression?
- Halothane and Enflurane
- While isoflurane, desflurane, and sevoflurane will produce vasodilation and have minimal effect on cardiac output
Which inhaled anesthetics have the most respiratory depression?
- Isoflurane and Enflurane
What may cause tonic-clonic movement at high concentrations?
Enflurane
What clinical setting should N2O be avoided?
- Pneumothorax
- Obstructed middle ear
- Air embolus
- Obstructed loop of bowel
- Intraocular air bubble
- Pulmonary bulla
- Intracranial air
What inhaled anesthetics can cause hepatotoxicity and nephrotoxicity?
- Halothane - potentially develop severe and life-threatening hepatitis; may need liver transplant
- Methoxyflurane - nephrotoxic potential due to fluoride released during metabolism
What is malignant hyperthermia, its symptoms, what anesthetics are it mainly triggered by, Tx, and test?
- Malignant hyperthermia is a AD trait causing a defect in the ryanodine receptor gene (RYR1) causing altered control of Ca2+ release from SR
- Tachycardia, HTN, severe muscle rigidity, hyperthermia, hyperkalemia, acidosis
- Triggered by Halothane and Succinylcholine
- Tx is Dantrolene which blocks Ca2+ release from SR
- Caffeine-Halothane Muscle Contracture Test to determine susceptibility
What inhaled anesthetic can cause hematotoxicity and how?
- N2O
- decreases methionine synthase activity > megaloblastic anemia
What are the IV anesthetics?
- Barbiturates: Thiopental and Methohexital
- Propofol
- Ketamine
- Etomidate
Ultra-short acting barbiturates uses, actions, AE
Thiopental and Methohexital
Uses: induction of anesthesia and for short surgical procedures
Actions: decrase intracranial pressure, no analgesia, may cause hyperalgesia
AE: apnea, coughing, chest wall spasm, laryngospasm, bronchospasm (concern for asthmatics)
Propofol uses, actions, AE
Uses: induction and maintenance of anesthesia; antiemetic
Actions: no analgesia, reduces intracranial pressure
AE: potent respiratory depressant, hypotension by decrease PVR
Etomidate uses, actions, AE
Uses: anesthetic induction in pts at risk for hypotension
Actions: no analgesic effects, reduces intracranial pressure
AE: N/V
Ketamine uses, actions, AE
Uses: produces dissociative anesthesia characterized by catatonia, amnesia, and analgesia with or without loss of consciousness
Actions: Blockade of NMDA receptors, increase intracranial pressure
AE: emergence phenomena with sensory and perceptual illusions/vivid dreams
What are adjuncts to anesthetics?
- Benzodiazepine: anxiolytic
- Opioid: analgesia
- Neuromuscular blockers: muscle relaxation
- Antiemetics: Ondansetron
- Antimuscarinics: scopolamine for amnesic and prevent salivation/bronchial secretions
