Stoelting Study 12 Epidural C

Front 1

test

Back 1

test

Front 2

99. Why might urinary retention occur after the administration of a spinal anesthetic?

Back 2

99. Urinary retention might occur after the administration of a spinal anesthetic because of the inhibition of bladder tone that results from the anesthesia. This can lead to bladder distention, requiring drainage by a catheter. BLadder distention can be ninimized by minimizing the amount of intravenous fluids administered to the patient while undergoing minor surgery with spinal anesthesia.

Front 3

102. Why is it important to consult a neurologist when nerve injury presents after a spinal anesthetic?

Back 3

102. It is important to consult a neurologist when nerve injury presents after a spinal anesthetic to establish a cause. If this is done early in the postoperative course the neurologist will be able to ascertain if the nerve injury is new or preexisting through the performance of electromyography.

Front 4

104. What were the circumstances under which spinal anesthesia resulted in cauda equina syndrome? What is the explanation for its occurrence?

Back 4

104. Cauda equina syndrome has been reported to occur after the administration of continuous spinal anesthesia through a 28-gauge microbore catheter in the subarachnoid space. It is believed now that the slow continuous injection through the catheter resulted in the highly concentrated exposure of urmyelinated neural tissue to hype~baric local anesthetic solution, causing irreversible damage [0 the nerve. The microbore catheters are 10 longer available for use.

Front 5

105. What is the incidence of paralysis with spinal anesthesia?

Back 5

105. The incidence of paralysis with spinal anesthesia is extremely rare. One retrospective review of over 582,000 spinal anesthetics cited an incidence of zero. (

Front 6

106. Whatis the difference in perioperative mortality in relatively healthy patients who underwent a scheduled elective surgery under spil,al anesthesia versus those who had general anesthesia?

Back 6

106. There was no difference in perioperative mortality between young, tealthy patients who underwent scheduled elective surgery under spinal anesthesia and similar patients who mderwent similar procedures under general anesthesia.

Front 7

107. What is contained in the sterile, prepackaged kits for epidural anesthesia?

Back 7

107. The sterile, prepackaged kits for epidural anesthesia typically contain lidocaine for local infiltration, saline for loss of resistance technique, a test dose of lidocaine with epinephrine, a loss of resistance syringe, a 17- or 18-gauge epidural needle and an epidural catheter, various other syringes and needles, drapes, and labels. Epidural catheters may have multiple orifices on the distal end to facilitate aspiration and contribute to the spread of local anesthetic in the epidural space

Front 8

108. Describe the procedure for placing an epidural catheter for epidural anesthesia using the loss of resistance technique.

Back 8

108. Epidural anesthesia is instituted in a similar fashion to spinal anesthesia. The patient is placed in a seated upright or lateral decubitus position with the back flexed as much as possible. The back is prepared and draped sterilely, local infiltration of the skin overlying the chosen interspace is administered, and the anesthesiologist proceeds to locate the epidural space. A 17- or 18gauge Tuohy needle is used to find the epidural space. The needle tip is curved to help prevent accidental puncture of the dura mater and to facilitate threading of the epidural catheter through the needle into the epidural space. The epidural space is locatable by the loss of resistance technique for anatomic reasons. First, the tough ligamentum fiavum overlies the space posteriorly, providing resistance to the needle as it passes through it. Second, there is negative pressure in the epidural space implying negative resistance. The change in resistance, or loss of resistance, as the needle passes through the ligamentum flavum into the epidUIal space accounts for the method by which anesthesiologists locate the epidural space. The anesthesiologist can sense the loss of resistance by connecting a syringe on the hub of the Tuohy needle and applying continuous gentle pressure on the plunger of the syringe as the needle is advanced through the ligaments into the epidural space. Once the epidural space is located with the Tuohy needle by the loss of resistance technique the epidural catheter can be threaded into the space, typically 2 to 5 cm. Epidural catheters that are threaded farther into the space are more likely to enter a vein, puncture the dura, or migrate into the intervertebral foramina. After the epidural catheter has been placed and the Tuohy needle has been pulled back, the epidural catheter is best secured in place by taping it to the patient's back.

Front 9

109. Why should the epidural catheter never be pulled back through the Tuohy needle?

Back 9

109. The epidural catheter, once threaded past the end of the Tuohy needle, must never be pulled back through the Tuohy needle for fear that this may result in shearing of the catheter in the epidural space. Instead, if the epidural catheter must be removed once it has exited the tip of the Tuohy needle, it is generally recommended that the needle and catheter be withdrawn together as a unit.

Front 10

110. What is the test dose for an epidural catheter? What is it testing for? How long must the anesthesiologist wait after administering the tea dose to be sure the result is negative?

Back 10

110. The test dose commonly used for the epidural catheter is 3 mL of 1.5% lidocaine with 1:200,OOO epinephrine. The test dose is performed to exclude the possibility that the epidural catheter has been accidentally placed into an epidural vein or into the subarachnoid space. The anesthesiologist must wait at least 3 minutes after the administration of the test dose to safely exclude these two possibilities.

Front 11

Ill. What would be seen as a result of the test dose if the epidural catheter were in an :lural vein?

Back 11

111. If the epidural catheter were in an epidural vein there would be a definitive, rapid, self-limited inclease in heart rate i~ response to the intravenous administration of 3 mL of 1:200,OOO epinephrine in the test dose

Front 12

112. What would be seen as a result of the test dose if the epidural catheter were in the subarachnoid space?

Back 12

112. If the epidural catheter were in the subarachnoid space, there would be a saddle area sensory and motor anesthetic block as a result of the subarachnoid injection of 45 mg of lidocaine in the test dose

Front 13

113. How should local anesthetic ~ administered through the epidural catheter for epidural anesthesia?

Back 13

113. The appropriate epidural dose of local anesthetic solution for the planned procedure should be estimated for administration. Typically, volumes of 15 to 25 II'L of local ane..<thetic are required in a lumbar epidural catheter to achieve an adequale level of ~DSOry analgesia for an abdominal procedure. The dose should be administered into the epidural space over 1 to 3 minutes. It is prudent to fractionate the administered dose, performing aspiration before the administration of each fraction, in the event that the catheter migrated or the epidural test dose was mistakenly believed to be negative.

Front 14

114. How is the level of anesthesia determined after the administration of an epidural anesthetic?

Back 14

114. The level 01 anesthesia after de administration of an epidural anesthetic is determined in a similar manner to that of a spinal anesthetic. The level of sympathetic nervous system blockade can be determined by the discrimination of temperature at various levels by using an alcohol sponge. The le\el of sensory rerve blockade can be detennined by the determination of a sharp object at various levels

Front 15

115. What is the single·,hot technique of an epidural anesthetic? When is it appropriate?

Back 15

115. The single-shot technique of an epidural anesthetic involves the administration of the local anesthetic solution Ihrough fue Tuohy needle when the dwation of anesthetic required for the procedure is short.

Front 16

116. What are the major influences over the level and duration of epidural anesthesia?

Back 16

116. There are two major influences over the level and duration of epidural anesthesia. First is the volume and concentration, or dose, of local arx:sthetic administered. Second is the presence or absence of epinephrine in the local anesthetic solution injected, The iXlsiuon of the patient during the administration 0' the local anesthetic solution in the epidural space hal minimal influence on the subsequent level of anesthesia achieved, although the more dependent side may have a more intense block than the nondependent side. The weight, height, and age of the patient and baricity of the local anesthetic solution do not influence the distribution of local anesthetic in the epidural space.

Front 17

119. What are two reasons for the relatively increased cephalad spread of local anesthetic as compared with caudad spread when injected into a lumbar epidural catheter

Back 17

119. The cephalad spread exceeds the caudad spread of local anesthesia when injected into a lumbar epidural catheter for two reasens. The first is because of the transmission of negative intrathoracic pressures in the cephalad portion of the space, drawing the anesthetic in a cephalad direction. Second, the resistance of the epidural space increases in the lumbosacral junction because of narrowing, making cephalad spread the path of least resistance.

Front 18

120. Why might a unilateral anesthetic block remit from an epidural anesthetic, despite proper technique?

Back 18

120. A unilateral anesthetic block may result from the administration of local anesthetic in the epidural space secondary to the plica mediana dorsalis, a connective tissue band in the epidural space that extends in a vertical direction between the ligamentum fiavum and dura mater dividing the epidural space in half.

Front 19

121. What is the major site of action of local anesthetic solutions placed in the · epidural space?

Back 19

121. The major site of action of local anesthetics administered in the epidural space is at the spinal nerve roots. At tbe spinal nerve roots the dura mater is relatively thin, allowing for the easiest diffusion of local anesthetic through the dura mater to the nerves.

Front 20

122. What is the mechanism by which the addition of epinephrine to local anesthetic solutions prolongs the duration of epidural anesthesia?

Back 20

122. The addition of epinephrine to a local anesthetic solution to be administered in the epidural space prolongs the duration by causing localized vasoconstriction in the area that the drug is administered. This results in decreased vascular absorption of the drug from that area and a prolonged amount of time in which the local anesthetic is in contact with the nerve roots at the administered concentration. The addition of epinephrine to local anesthetic solutions for administration in the epidural space seeIlli to prolong the duration of lidocaine more than bupivacaine.

Front 21

123. What is an explanation for the often observed delay in onset of epidural anesthesia in the SI-S2 region?

Back 21

123. The~e is often a delayed onset in anesthesia at the Sl-S2 nerve root region during m epidural anesthetic. This may be due to the covering of these nerve roots with connective tissue, slowing the diffusion of local anesthetic to these nerve roots.

Front 22

124. How much does diffusion of local anesthetic into the subarachnoid space contribute to the anesthesia produced by an epidural?

Back 22

124. The diffusion of local anesthetic from the epidural space to the subarachnoid space is a minor contributor to the anesthetic effects of local anesthetic solutions in the epidural space.

Front 23

125. How does epidural anesthesia compare with spinal anesthesia with regard to the various levels of blockade of the sympathetic, sensory, and motor nerves?

Back 23

125. Epidural anesthesia results in sympathetic nerve blockade, sensory nerve blockade, and motor nerve blockade just as in spinal anesthesia. In epidural anesthesia, however, the levels of each are different than they are in spinal anesthesia. Firs~ sympathetic nerve blockade is at a level equal to sensory nerve blockade, rather than the two to six segments higher that is seen in spinal anesthesia. Second, motor nerve blockade may average four segments lower than sensory nerve blockade, rather than the two segments seen in spinal anesthesia.

Front 24

126. How does the vascular absorption of epinephrine from its addition in a local anesthetic solution administered in the epidural space affect blood pressure?

Back 24

126. The vascular absorption of epinephrine from the epidural space when administered as part of a local anesthetic solution results in very low systemic plasma levels. These low levels may result in primarily beta-agonist effects, augmenting the vasodilation and decrease in blood pressure seen when local anesthetics are administered one, (182)

Front 25

127. How does epidural anesthesia compare with spinal anesthesia with regard to its effects on the respiratory system and gastrointestinal system?

Back 25

127. Epidural anesthesia produces similar effects as spinal anesthesia on the respiratory and gastrointestinal systems.

Front 26

128. What are some potential side effects of epidural anesthesia?

Back 26

128. The potential side effects of spinal anesthesia also apply to epidural anesthesia. Addiional side effects of an epidrral lIlesthetic that do not apply to spinal anesthesia include the risks of accidental dural puncture, local anestheic toxicity, subdural injection. and epidural hematoma formation.

Front 27

129. What is the risk of epidural hematoma formation resulting from an epidural anesthetic?

Back 27

129. The risk of epidural hematoma formation resulting from an epidural anesthetic is extremely low. Patients on anticoagulants are considered to be at the : greatest risk, although the incidence is extremely low even in patients with bleeding abnormalities. There are multiple reviews in the literature of patients who received anticoagulation intraoperatively and postoperatively without any neurologic sequelae. Nevertheless, the American Society of Regional Anesthesia published their consensus statement titled Neuraxial Anesthesia and Anticoagulation in May 1998 with their recommendations on how epidural catheters should be managed in the perioperative period in the presence anticoagulation.

Front 28

l30. What are some indications of accidental dural puncture during the performance of epidural anesthesia? How should it be managed?

Back 28

130. Accidental puncture of the dura rruter during attempted localization of the epidural space can be recognized by the anesthesiologist by the appearance of cerebrospinal fluid in the hub of the epidural medle. The flow of cerebrospinal fluid from the large-bore needle is rapid and continuous. Cerebrospinal fluid is warm, distinguishing it from saline used for the loss of resistance technique for localization of the epidural space. Cerebrospinal fluid will also test positive for glucose. Once accidental dural puncture during attempted epidural anesthesia has occurred, the anesthesiologist may convert to a spinal anesthetic. Alternatively, the needle may be removed and reattempt tV (1 1>pllli:U atlt:SmenC, Auemanveiy, the needle may be removed and reattempt puncture headache after accidental dural puncture with an I8-gauge epidural needle is likely, given the size of the hole in the dura mater produced by the relatively large needle. For this reason the patient should be infonned about the possibility of a postdural puncture headache and should be instructed as to whom to contact for evaluation and treatment should a postdural puncture headache occur

Front 29

131. What results from the unrecognized, accidental subarachnoid injection of local anesthetic when administering an epidural anesthetic?

Back 29

131. The accidental subarachnoid injection of the large volumes of local anesthetic intended for epidural anesthesia results in a rapidly evolving total spinal.

Front 30

132. What results from the unrecognized, accidental subdural injection of local anesthetic when adrninisterinE an epidural anesthetic'?

Back 30

132. The accidental subdural injection of the large volumes of local anesthetic intended for epidural anesthesia results in a slowly evolving total spinal. A subdural injection of local anesthetic may be difficult to recognize. (

Front 31

l33. What is the potential risk of local anesthetic systemic toxicity when administering an epidural anesthetic?

Back 31

133. The potential for local anesthetic systemic toxicity with epidural anesthesia is high because of the high doses of local anesthetic that must be given to produce epidural anesthesia, coupled with the numerous venous plexuses found in the epidural space that lend themselves to systemic absorption of the local anesthetic. Even so, blood levels of local anesthetic administered in the epidural space are rarely in the toxic range. The risk of systemic toxicity from the systemic absorption of local anesthetic administered in the epidural space is decreased by the addition of epinephrine to the local anesthetic solution. Epinephrine in the local anesthetic solutions slows the rate of systemic absorption of the local anesthetic in the epidural space

Front 32

134. How does the hypotension associated with epidural anesthesia compare with that associated with spinal anesthesia?

Back 32

134. Epidural anesthesia results in less abrupt hypotension than spinal anesthesia, owing to the slower onset of sympathetic nervous system blockade in epidural anesthesia. The treatment for hypotension resulting from epidural anesthesia is placing the patient in a modest head-down position, the administration of intravenous fluid3, and, if necessary, the administration of sympathomimetics.

Front 33

135. What can result from the unrecognized, accidental intravascular injection of local anesthetic when administering an epidural anesthetic?

Back 33

135. The accidental intravascular injection of the large volumes of local anesthetic intended for epidural anesthesia can result in local anesthetic toxicity. This may manifest as cardio'lascuiar collapse, apnea, seizures, and unconsciousness. In the event this occurs, rapid treatment of the seizures and cardiovascular and ventilatory support are indicated

Front 34

136. What is the technique for administering a combined spinal and epidural anesthetic?

Back 34

36. A combined spinal and epidural anesthetic is performed by passing a spinal needle through the large-bore Tuohy needle once localization of the epidural aken place. When the needle is confirmed to be in the subarachnoid space, local anesthetic and/or narcotic can be deposited into the subarachnoid space. The spinal needle is then removed, and an epidural catheter may be threaded through the Tuohy needle and secured. This technique allows for the rapid OI1<>et of anesthesia, while still allowing for a method to extend the duration ,)f the anesthetic and/or provide for postoperative analgfsia via the use of the epidural catheter. There are now Tuohy needles designed specifically for this technique.

Front 35

137. 'What position should the patient be in to facilitate the administration of a caudal anesthetic?

Back 35

137. To facilitate the administration of a caudal anesthetic the adult patient should be in the prone position, whereas the pediatric patient may be in the lateral decubitus position.

Front 36

138. Where is the sacral hiatus located?

Back 36

138. The sacral hiatus is located between the sacral cornua approximately 5 cm from tt.e tip of the coccyx.

Front 37

139. Where and how is the needle placed for a caudal anesthetic? .

Back 37

139. For the administration of a cauda1 anesthetic the needle is first introduced through the sacrococcygeal ligament perpendicular to the skin. After contact with the sacrum, the needle is withdrawn slightly and redirected at a slightly reduced angle about 2 em into the caudal canal. The needle is then appropriately placed for the administration of the local anesthetic for caudal epidural anesthesia.

Front 38

140. How can it be confirmed that the needle tip is appropriately placed in the caudal canal for a caudal anesthetic?

Back 38

140. Confirmation that the needle tip is appropriately placed in the caudal canal for the administration of local anesthetic can be made by injecting about 5 mL <f saline or air. If the leedle is subcutaneously placed, subcutaneous air or a subcutaneous bulge will appear overlying the tip of the needle. Aspiration on the needle be~)re injection would result in the appearance of cerebrospinal fluid in the syringe if the needle were erroneously placed in the subarachnoid space.

Front 39

141. Given the proximity of the rectum to the site of needle insertion Dr a caudal anesthetic, how frequently is infection noted with this technique?

Back 39

141. Although the rectum is in close proximity to the point of needle insertion in a caudal epidural anesthetic, the incidence of infection is rare

Front 40

142. What is a potential risk of caudal anesthesia?

Back 40

142. A potential risk of caudal anesthesia is S.lbarachnoid injection of the local anesthetic. The dural sac ends at S2. The risk of sumachnoid injection of local anesthetic during a caudal anesthetic is therefore limited if the tip of the needle does not extend beyond S2. In addition, the anesthesiologist should , aspirate on the needle before the administration of the local anesthetic solution to confirm the absence of cerebrospinal fluid.

Front 41

143. What is the failure rate of caudal anesthesia?

Back 41

143. The failure rate of caudal anesthesia is as high as 10% secondary to anatomic anomalies of the caudal canal. If failure of the technique occurs, the anesthesiologist may proceed to do a lumbar epidural anesthetic. (

Front 42

144. How does technical ease of the administration of a caudal anesthetic in children compare with the ease of Its adminIstration in an adult?

Back 42

144. The performance of a caudal anesthetic is technically easier in children than in adults.