Exam 3: Inhaled Anesthetics 2 PPT Flashcards
What are the positive effects of Nitrous oxide?
Good analgesia, 2nd gas effect
Nitrous oxide is commonly used for its analgesic properties and can enhance the effects of other anesthetics.
What are the negatives associated with Nitrous oxide?
Nausea/Vomiting > 50%, ↑ PVR, may increase right-to-left shunt in neonates, jeopardizes arterial oxygenation
These side effects can complicate its use, particularly in sensitive populations.
What is the solubility and potency of Nitrous oxide?
Low solubility, low potency
Nitrous oxide cannot deliver 1 MAC (Minimum Alveolar Concentration), making it unsuitable as a sole anesthetic.
Does Nitrous oxide produce skeletal muscle relaxation?
No
Nitrous oxide is not effective for inducing muscle relaxation.
What is the cardiovascular effect of Nitrous oxide?
No cardiac depression
Nitrous oxide does not cause depression of cardiac function.
What happens to heart rate with Nitrous oxide?
Dose-dependent increases
Heart rate increases with higher doses of Nitrous oxide.
What is the effect of volatile anesthetics on cardiac output?
Dose-dependent decrease in CO, offset by mild increase in HR
Modern volatiles can cause a decrease in cardiac output.
What is the neuroendocrine stress response associated with anesthesia?
Activation of ANS and HPA, perioperative surge in catecholamines, ACTH, cortisol
This response can affect immune function and recovery.
What is the effect of inhaled anesthetics on hypoxic pulmonary vasoconstriction?
Dose-dependent decrease in response
This can be particularly concerning during one-lung ventilation.
How do inhaled anesthetics affect the carbon dioxide response curve?
Blunt hypoxic and hypercarbic response
This occurs at various MAC levels, leading to respiratory depression.
What is the effect of Nitrous oxide on cerebral blood flow?
Dose-dependent increase in CBF due to decreased cerebral vascular resistance
This may lead to increased intracranial pressure (ICP).
What is the relationship between inhaled anesthetics and ICP?
ICP parallels increases in CBF
Patients with space-occupying lesions are at greater risk.
What is the impact of anesthesia on hepatic blood flow?
Total hepatic blood flow maintained, hepatic artery flow maintained, portal vein flow increased
Isoflurane, desflurane, and sevoflurane have similar effects.
What are the two types of liver toxicity associated with halothane?
Type I: Direct toxic effect; Type II: Immune-mediated response
Type I occurs 1-2 weeks after exposure, while Type II occurs 1 month after exposure.
What is the metabolism of sevoflurane?
Metabolized to vinyl halide, not capable of stimulating antibody formation
This makes it less likely to cause immune-mediated liver toxicity.
What is the effect of Nitrous oxide on Vitamin B12?
Oxidizes cobalt ion in B12, inhibits methionine synthase, inhibits DNA synthesis
This can lead to megaloblastic anemia.
What is the incidence of postoperative nausea and vomiting (PONV) with Nitrous oxide?
25-30% incidence with general anesthesia using two triggering agents
Nitrous oxide > 0.5 MAC increases the risk of PONV.
What is malignant hyperthermia?
Uncommon genetic condition triggered by volatile agents and succinylcholine
It results in a hypermetabolic state of skeletal muscle, with high mortality if untreated.
What is the effect of inhaled anesthetics on renal function?
Dose-dependent decrease in RBF, GFR, and U/O
Preoperative hydration can help mitigate these effects.
What is ‘Compound A’ associated with sevoflurane?
Formation from carbon dioxide absorbents and sevoflurane metabolism
It is nephrotoxic and can lead to acute tubular necrosis (ATN).
What is the CNS activity of inhalation anesthetics?
Dose-dependent decrease in CMRO2 and cerebral activity
Begins around 0.4 MAC, reaching electrical silence at 2 MAC.
What is the effect of inhalation anesthesia on neuromuscular function?
Dose-dependent skeletal muscle relaxation
Nitrous oxide does not relax skeletal muscles.
What is the effect of inhalation anesthesia on respiratory resistance?
Baseline pulmonary resistance unchanged by 1-2 MAC
Bronchodilation occurs with sevoflurane but may worsen with desflurane.
What are the types of anesthesia circuits?
Rebreathing (Bain), Non-breathing (self-inflating BVM), Circle systems
Different systems are used for delivering oxygen and inhaled drugs.
