PQR - Epidural Block Test Questions with Correct Answers Graded A+

PQR - Epidural Block Test Questions with Correct Answers Graded A+ 529: What structures are contained within the epidural space? - Answers Epidural fat, a dense venous plexus (Batson's plexus), and segmental arteries are contained within the epidural space. 1543: What are the anatomic borders of the epidural space? - Answers The epidural space extends vertically from the foramen magnum to the sacral hiatus. Anteriorly, it is bordered by the posterior longitudinal ligament. Posteriorly, it is bordered by the vetebral lamina and the ligamentum flavum which adjoins it. The vertebral pedicles constitute an incomplete lateral border. 1991: With what venous system does the epidural venous plexus communicate and what is the significance of this? - Answers Batson's plexus in the epidural space is a valveless system of veins that communicates with the azygous system. This could potentially result in engorgement of the vessels during instances of increased abdominal pressure. 2331: What size needle is usually used for an epidural block? - Answers 3-inch long, 16 to 18 gauge needles are usually used 3065: What is the difference between a Crawford needle and a Tuohy needle? - Answers A Crawford needle has thinner walls with a traditional point beveled at about 45 degrees. A Tuohy needle is beveled, but the end of the needle bends upward 3207: Why would one choose a Crawford needle over a Tuohy needle? - Answers The Tuohy needle allows for easier threading of the epidural catheter when approaching the epidural space perpendicularly. The bend in the needle tip assists in directing the catheter tip upward. When using a more acute angle, such as a paramedian approach, the straight needle tip of the Crawford needle provides a better angle for threading the catheter upward. 3241: What is the Loss of Resistance technique for correct epidural catheter placement? - Answers As the epidural needle reaches the ligamentum flavum, an air or fluid-filled syringe is connected to the needle. Continuous, mild pressure is applied to the plunger as the needle is advanced. As soon as the epidural space is entered, there will a dramatic loss of resistance on the plunger which verifies the correct location. 3323: The Loss of Resistance technique can be performed using either saline or air. Why would you choose one over the other? - Answers In patients presenting for lithotripsy, there is the possibility that turbulence at the air-water interface could cause neural damage if air is used. 3377: What is the Hanging Drop technique? - Answers The hanging drop technique is used to verify that the epidural needle has passed through the ligamentum flavum into the epidural space. A visible drop of fluid is placed on the hub of the epidural needle. Because the epidural space has a slightly negative pressure, as the needle enters the epidural space, the drop of fluid will be sucked into the epidural space. 3383: You are performing an epidural block and begin threading the catheter. The patient describes tingling in her left leg. You encounter no unusual resistance as you thread the catheter. What should you do? - Answers Prior to placing an epidural catheter, you should warn the patient that they may experience a tingling sensation in one or both legs as the catheter is advanced. The paresthesia may occur if the catheter brushes a nerve root. 3407: What is the standard 'test dose' for an epidural anesthetic? - Answers The standard test dose for epidural anesthesia contains 3 mL of 1.5% lidocaine and 1:200,000 epinephrine or 15 mg/mL of lidocaine and 5 mcg/mL of epinephrine. A test dose contains a total of 45 mg lidocaine and 15 mcg epinephrine. 3492: Where is the epidural space the largest? - Answers The epidural space is largest in the midline of the lumbar region at about 5-6 cm wide. 3509: Where are lumbar epidurals usually placed and why? - Answers Lumbar epidurals are typically placed between L2-L3, L3-L4, L4-L5 and occasionally at the L5-S1 interspace. It is considered safer to place a lumbar epidural below the level of L1, because that is where the spinal cord terminates in most adults and the risk of spinal cord injury is reduced. Levels higher than L2 require an experienced practitioner. 3758: What is a differential block and how can this be applied in epidural anesthesia? - Answers A differential, or segmental block occurs when the height at which motor, sensory, and autonomic block differ. This can be useful in many circumstances. For example, the administration of a dilute concentration of local with a small amount of opioid can be sufficient to block the smaller diameter pain fibers while sparing the motor fibers. This would allow for pain relief while allowing the patient to retain motor control. 3824: How does the onset of anesthesia with an epidural block compare to that of a spinal block? - Answers The onset of anesthesia with an epidural is much slower than that of a spinal block and usually takes between 10-20 minutes. 3902: Segmental spread of an epidural block is primarily dependent upon what two factors? - Answers The segmental spread of an epidural is reliant primarily upon the volume of local anesthetic solution used and the site of injection. The size of the epidural space increases down the spinal cord as the cord itself occupies less space. This is in contrast to spinal anesthesia, which relies more on the dose in milligrams of the local anesthetic, the baricity of the solution, and the patient's position to determine the spread of the anesthetic. 3983: You are performing an epidural using a saline-filled syringe and the loss of resistance technique. When you aspirate the syringe, fluid flows back. How can you confirm that the fluid is saline and not cerebrospinal fluid? - Answers CSF can be distinguished from saline or local anesthetic in a few ways. It is warm (body temperature rather than room temperature) and it will test positive for glucose.