Neuraxial Analgesia Flashcards
T or F: Epidural infusions lasting < 24 hours do not appear to offer any clear cardiovascular advantages.
True
T or F: Epidurally administered opioids have the distinct advantage of producing analgesia without causing significant sympatholytic effect or motor blockade.
True- analgesia occurs by way of a spinal mechansim, which occurs following diffusion of the drug into the spinal fluid.
T or F: Opioids with intermediate lipophilicity have the ability to easily move between aqueous and lipid regions of arachnoid membrane.
Morphine has the greater bioavailability in spinal cord.
Thoracic epidural catheter placement is recommended for both thoracic and upper abdominal surgical procedures because of observed:
- improvement in coronary artery blood flow
- attenuation of pulmonary complications
- reduction in duration of postoperative ileus
Epidural administration of hydrophilic opioids vs lipophilic opioids
- in general, epidural administration of hydrophilic opioids tends to have slow onset, long duration, and mechanism of action that is primarily spinal in nature.
- epidural administration of lipophilic opioids has quick onset, short duration, and supraspinal mechanism of action secondary to rapid systemic uptake.
What is the CSF volume in humans?
Approximately 100-160 mL
What is the rate of CSF production in humans?
20-25 mL/hr
How frequently is the entire CSF volume replaced?
Every 6 hours
True or false: CSF cannot be relied on to distribute drugs in the subarachnoid space.
True
True or false: CSF does not circulate, rather it oscillates in the cephalocaudal axis with a frequency equal to the heart rate.
True
True or false: spinal blockade leads to decreased sympathetic outflow, leading to unopposed parasympathetic influences.
True
True or false: Cardiac arrest in healthy patients following spinal anesthesia has been thought to be mediated by unopposed vagal influences on the heart when the cardioaccelerator fibers (T1-T4) are blocked in susceptible individuals.
True
What does differential block refer to?
Refers to the clinically important phenomenon in which nerve fibers have different sensitivities to local anesthetic blockade.
An example would be that sympathetic nerve fibers appear to be blocked by the lowest concentration of local anesthetic followed in order by fibers responsible for pain, temperature, touch, and motor function.
True or false: Spinal and epidural anesthesia differential block is manifested as a spatial separation that is believed to be a result of a gradual decrease in local anesthetic concentration within the CSF as a function of distance from the site.
True
True or false: central neuraxial block produces sedation, potentiates the effects of sedative hypnotic drugs, and markedly decreases the MAC of volatile anesthetics.
True