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“Kiddie” Caudal

Safe but More to Learn

Boretsky, Karen R., MD; DiNardo, James A., MD

doi: 10.1213/ANE.0000000000000532
Editorials: Editorial

From the Department of Anesthesia, Boston Children’s Hospital, Boston, Massachusetts.

Accepted for publication September 17, 2014.

Funding: No funding.

The authors declare no conflicts of interest.

Reprints will not be available from the authors.

Address correspondence to James A. DiNardo, MD, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115. Address e-mail to

Epidural analgesia administered via the caudal space, AKA, the “kiddie caudal,” became a common procedure in pediatric anesthesia over 30 years ago. Many small- and medium-sized studies have attested to its safety. None of these studies has been sufficiently powered to detect infrequent complications.

In this issue of Anesthesia & Analgesia, Suresh et al.1 analyze a large database to determine the safety of caudal blocks for postoperative pain relief in children. Using data from the Pediatric Regional Anesthesia Network (PRAN), founded under the auspices of the Society of Pediatric Anesthesia, the authors provide valuable information on the safety of the most commonly used regional anesthetic technique in children. The authors looked at the outcome of caudal blocks in 18,650 infants and children. In this large population, there were no temporary or permanent sequelae. Zero, it is a reassuring number.

However, there are reasons to be cautious about interpretation of the data. The authors identify the main weakness of their study: the PRAN database does not capture highly detailed information. Specifically, the PRAN database lacks detailed information on block efficacy, surgical procedures, or underlying patient comorbidities. This is a common trade-off when using a large retrospective database to obtain a large N to look at the outcome of an intervention. For this reason, important questions remain unanswered.

  1. Although age explains some of the variation in dose, there may be other explanations for dose variation. Some of the dose variation is likely related to the type of surgery (e.g., bilateral inguinal hernia versus clubfeet repair) and the distribution of different surgical procedures in different age groups. It is also likely that more dilute solutions (lower doses) were more commonly used in older children to avoid motor block in ambulatory patients. Therefore, although it is true that proportionally higher doses were given in younger patients, the reason and significance of this finding are unclear. There is no evidence to suggest that neonates and infants are at increased risk of local anesthetic systemic toxicity after a single dose of local anesthetic.
  2. Block failure, the most common complication, is easier to detect in awake, sedated patients than in patients under general anesthesia. Perhaps younger patients (e.g., former “premies”) were more likely to have their block placed awake or under sedation, making technical failures more apparent. Patients were not otherwise rigorously tested for absence or presence of block. Is this the explanation for a higher complication rate? We do not know.
  3. The authors’ definition of potentially unsafe doses of local anesthetic is stringent and potentially confusing. The literature and standard texts support a long-standing upper limit of 2.5 mg/kg of bupivacaine, increased to 3 mg/kg if epinephrine is added. The 24.6% of practitioners giving between 2.0 and 2.5 mg/kg were within the standard of practice. Without knowing if epinephrine was coadministered, it is not clear how many, if any, of the 5.4% of patients receiving >2.5 mg/kg were outside of the guidelines of standard practice. Of note, the 2 cases of systemic toxicity occurred after doses well below 2 mg/kg.
  4. After adjusting for local anesthetic potency, why did patients undergoing caudal block with ropivacaine receive a larger dose and a wider range of doses of local anesthetic than those undergoing caudal block with bupivacaine? Do practitioners believe that ropivacaine is safer? Are we pushing the envelope on the upper dose limit on ropivacaine?

Large computerized databases provide information previously unavailable. However, they introduce potential pitfalls of statistical errors associated with “overpowered” studies. When looking at dosing patterns with and without epinephrine, it is unlikely that the difference of 1.3 mg/kg (IQR, 1.2–1.6) bupivacaine without epinephrine versus 1.4 mg/kg (IQR, 1.2–1.6) bupivacaine with epinephrine is clinically significant or relevant, despite the P value of 0.001. We need to cautiously interpret the small P values generated in the analysis of very large databases.

Suresh et al. provide reassuring data on the safety of regional anesthesia in infants and children. However, as the authors point out, more research is needed. Despite the lack of evidence for complications, the article is not a carte blanche on the safety of the kiddie caudal.

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Dr. James A. DiNardo is the Section Editor for Pediatric Anesthesiology and Pediatric Neuroscience for the Journal. This manuscript was handled by Dr. Steven L. Shafer, Editor-in-Chief, and Dr. DiNardo was not involved in any way with the editorial process or decision. E

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Name: Karen R. Boretsky, MD.

Contribution: This author helped write the manuscript.

Attestation: Karen R. Boretsky approved the final manuscript.

Name: James A. DiNardo, MD.

Contribution: This author helped write the manuscript.

Attestation: James A. DiNardo approved the final manuscript.

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1. Suresh S, Long J, Birmingham PK, De Oliveira GS Jr. Are caudal blocks for pain control safe in children? An analysis of 18,650 caudal blocks from the Pediatric Regional Anesthesia Network (PRAN) database. Anesth Analg. 2015;120:151–6
© 2015 International Anesthesia Research Society