**9. Novel clinical application of older mature nerve block technique by use of ultrasound technology: caudal block**

Improvements in ultrasound technology have resulted in the return of some older mature nerve block techniques to clinical importance, as also seen with LMWD. One of those is cau‐ dal block. Since a high level of skill is required to safely perform an adequate caudal block in older adults, because of anatomical deformity of the sacrum associated with aging, it is rarely performed in elderly patients and generally believed to be a special nerve block technique for use in pediatric cases. However, ultrasound technology has made it much easier to safely perform a caudal block with high consistency in older patients [2].

We studied the clinical usefulness and availability of a caudal block for urinary cath‐ eter‐induced bladder discomfort in adult patients, which is common in those who have undergone urinary catheterization during surgery. In some cases, the discomfort is severe, causing restlessness and agitation after emergence from anesthesia, with post‐ operative recovery sometimes disrupted due to the continual uneasiness. These adverse effects are more pronounced in middle‐aged and elderly male patients due to anatomic considerations.

Muscarinic receptor antagonists, such as ketamine and gabapentin, have been shown to be effective for relieving postoperative bladder discomfort caused by a catheter. However, they may alter hemodynamics, leading to dry mouth or excessive sedation. In view of such unwanted side effects, these agents may not be best for treatment of bladder discomfort in all patients. Since caudal block anesthesia is used in the fields of urological and gyneco‐ logical surgery, we speculated that ultrasound‐guided single shot anesthesia by a caudal block would be a reliable and safe method for relief of urinary catheter‐induced bladder discomfort.

We enrolled male patients (ASA I‐II) older than 50 years who were scheduled for cervical spine surgery, and allocated them to either the caudal block (Group CB, *n* = 22) or non‐block (Group NB, *n* = 22) group. Following induction of anesthesia, urinary catheterization was performed using a 16‐F Foley catheter. In Group CB, an ultrasound‐guided single shot caudal block was additionally performed before the start of surgery using an 8‐ml mixture of 0.3% ropivacaine and 100 μg of fentanyl. Group NB did not undergo a caudal block or receive any other drugs. Thereafter, spine surgery started. The severity of urinary catheter‐related discomfort was assessed at 0 (just after arrival in the post‐anesthesia care unit), then 2, 10, and 18 h after the operation.

Nevertheless, use of LMWD as a local anesthetic adjuvant has nearly been forgotten in recent years. We rediscovered its value with the aid of ultrasound technology and found that use of LMWD with a local anesthetic mixture is a good option to further improve the performance of TAPB or RSB, and likely other regional anesthesia procedures as well. Extension of the analgesia period to the next day after surgery by a simple single‐shot approach is fully adequate for most surgery patients, making unnecessary the compli‐ cated procedure of inserting a catheter for continuous administration and subsequent management during the postoperative period. Thus, use of LMWD makes regional anes‐ thesia more easily accessible to many anesthesiologists and may open a new horizon for

**9. Novel clinical application of older mature nerve block technique by** 

Improvements in ultrasound technology have resulted in the return of some older mature nerve block techniques to clinical importance, as also seen with LMWD. One of those is cau‐ dal block. Since a high level of skill is required to safely perform an adequate caudal block in older adults, because of anatomical deformity of the sacrum associated with aging, it is rarely performed in elderly patients and generally believed to be a special nerve block technique for use in pediatric cases. However, ultrasound technology has made it much easier to safely

We studied the clinical usefulness and availability of a caudal block for urinary cath‐ eter‐induced bladder discomfort in adult patients, which is common in those who have undergone urinary catheterization during surgery. In some cases, the discomfort is severe, causing restlessness and agitation after emergence from anesthesia, with post‐ operative recovery sometimes disrupted due to the continual uneasiness. These adverse effects are more pronounced in middle‐aged and elderly male patients due to anatomic

Muscarinic receptor antagonists, such as ketamine and gabapentin, have been shown to be effective for relieving postoperative bladder discomfort caused by a catheter. However, they may alter hemodynamics, leading to dry mouth or excessive sedation. In view of such unwanted side effects, these agents may not be best for treatment of bladder discomfort in all patients. Since caudal block anesthesia is used in the fields of urological and gyneco‐ logical surgery, we speculated that ultrasound‐guided single shot anesthesia by a caudal block would be a reliable and safe method for relief of urinary catheter‐induced bladder

We enrolled male patients (ASA I‐II) older than 50 years who were scheduled for cervical spine surgery, and allocated them to either the caudal block (Group CB, *n* = 22) or non‐block (Group NB, *n* = 22) group. Following induction of anesthesia, urinary catheterization was performed

**use of ultrasound technology: caudal block**

perform a caudal block with high consistency in older patients [2].

them.

40 Current Topics in Anesthesiology

considerations.

discomfort.

Following are details of our method for ultrasound‐guided caudal block. With the patient in a prone position, the location and structure of the sacral hiatus are confirmed on sonographic trans‐ verse and longitudinal images. Next, a 23‐gauge block needle is inserted in the direction of the sacral canal through the sacral hiatus while monitoring real‐time sonographic images (**Figure16**), then the tip of the block needle is inserted into the sacral canal at least 1 cm ahead. After nega‐ tive aspiration, a mixture of ropivacaine and fentanyl is injected. Injection of that mixture into epidural space is confirmed by ultrasound images showing that the block needle is properly inserted in the direction of the sacral canal through the sacral hiatus, while a small fraction of injection fluid in the depth of the sacral canal shows reverse spreading into the canal opening portion near the sacral hiatus.

All caudal block procedures in this study were guided by ultrasound and successfully per‐ formed without severe difficulties. Following surgery, the incidence rate of urinary cath‐ eter‐induced discomfort was significantly reduced in Group CB as compared to Group NB (**Figure 17**). There were no complications related to caudal block anesthesia, including bleeding or hematoma at the injection site. No motor block of the extremities was observed and none of the patients required re‐catheterization due to urinary retention after catheter removal. These results showed that ultrasound‐guided single shot caudal block anesthesia can reduce the incidence and severity of postoperative urinary catheter‐induced bladder discomfort.

Our findings of reduced difficulties and improved reliability with use of ultrasound guid‐ ance indicate that a caudal block can be used in adults for bladder discomfort treatment, as well as various other procedures performed in the lower abdomen region, including pelvic, bladder, perineal, genital, rectal, and anal surgery, namely, inguinal and femoral herniorrhaphy, cystoscopy, urethral surgery, prostatectomy, hemorrhoidectomy, vaginal hysterectomy, and other surgeries of the perineum, anus, and rectum. The effectiveness of a caudal block for postoperative analgesia in patients undergoing such operations is also promising.

We now consider that a caudal block can be accurately and safely performed in adults with ultrasound guidance. In addition, its application in combination with general anesthesia is expected to improve the quality of anesthesia, as shown with TAPB. In particular, a caudal block may be more suitable for high‐risk cases, as the technique is simple with minimum hemody‐ namic effects.

**Figure 16.** Ultrasound probe positioning and ultrasound images obtained during performance of caudal block.

Regional Anesthesia: Advantages of Combined Use with General Anesthesia and Useful Tips for Improving... http://dx.doi.org/10.5772/66573 43

**Figure 17.** Effects of caudal block to alleviate catheter‐induced bladder discomfort. The patients in Group CB (*n* = 22) received a caudal block with 8 ml of 0.3% ropivacaine and 100 μg of fentanyl after anesthesia induction, while those in Group NB (*n* = 22) did not receive a caudal block. The incidence rate of urinary catheter‐induced bladder discomfort was significantly lower in Group CB when compared to Group NB at 0, 2, and 6 h after surgery.
