The effect of flexion on the level of termination of the dural sac in paediatric patients

The Implementation and Optimization of Neonatal Epidural Analgesia in a Tertiary Care Hospital: A Technical Report

Effective analgesic therapy in neonates continues to be fundamental for improving quality of life and decreasing the need for further medical intervention. When pain is not well controlled in the neonatal intensive care setting, we see an increased use of sedation pharmaceuticals, mechanical ventilation, and altered somatosensory development, among other complications. Currently, there is no standardized protocol addressing effective pain management while decreasing the need for further sedation. In this article, we seek to demonstrate how our institution standardized and implemented the utilization of epidural analgesia in neonates as the preferred method of pain management for open thoracic and abdominal surgeries.

Ultrasound determination of the dural sac to sacrococcygeal membrane distance in premature neonates

Background

Caudal epidural analgesia is the most common regional anesthetic performed in infants. Dural puncture, the most common serious complication, is inversely proportional to age. Measuring the distance from the sacrococcygeal membrane to the dural sac may prevent dural puncture. This study measures the sacrococcygeal membrane to dural sac distance using ultrasound imaging to determine feasibility of imaging and obtaining measurements.

Methods

Sacral ultrasound imaging of 40 preterm neonates was obtained in left lateral decubitus, a typical position for caudal blockade. No punctures were made. The sacrococcygeal membrane and termination of the dural sac were visualized, and the distance measured. The spinal levels of the conus medullaris and dural sac termination were recorded.

Results

20 males and 20 females former preterm neonates with an average weight (SD; range) of 1740 (290; 860–2350) g and average age (SD; range) of 35.0 (1.35; 32.2–39) weeks gestational age at the time of imaging. The average sacrococcygeal membrane to distal dural sac distance (SD; range) was 17.4 (3.1; 10.6–26.3) mm. Overall, the weights correlated positively with the distance but the coefficient of variation was large at 23%. The conus medularis terminated below the L3 level and dural sac below the S3 level in 20% and 10% of subjects respectively with hip flexion.

Conclusion

Ultrasound can be used to measure the sacrococcygeal membrane to dura distance in preterm neonates prior to needle insertion when performing caudal block and demonstrates large variability. Ultrasound imaging may identify patients at risk for dural puncture. When ultrasound is not available, needle insertion less than 3 mm/kg beyond the puncture of the sacrococcygeal membrane should prevent dural contact in 99.9% of neonates.

Correlation of correct needle placement in caudal epidural space and anatomical structures of sacral canal in paediatric patients: An observational study

Background and Aims:

Caudal epidural block (CEB) is commonly performed using surface landmark-based technique in the paediatric patients, with a good success rate. Failure to perform CEB is usually attributable to anatomic variations. The aim of this study was to perform measurements of the anatomical landmarks that are generally used to perform CEB and find a relation between these measurements and successful needle placement.

Methods:

This was an observational study that included 114 patients, aged up to 15 years. Ultrasonography (USG) scan of the sacrococcygeal region with measurement of cornu height, skin to cornu distance, inter-cornu distance (ICD), vertical and oblique size of hiatus were done. Needle placement for CEB was done using the usual palpatory hiatal approach. Needle position was checked by using ultrasound. Spearman correlation coefficient and multi-variate logistic regression were used for measuring the correlation and predictors of correct needle placement, respectively.

Results:

Correct placement of needle was found in 84% patients. Statistically significant correlation was found between all the anatomical parameters. Regression analysis revealed that only ICD had a statistically significant contribution (OR1.67, 95% CI 1.024–2.7; P = 0.04) in predicting an incorrect needle placement. If ICD was less than 12.5 mm, it predicted a difficult needle placement; all the children were less than 1.5 years in age; AUC was 77%, P = 0.001, sensitivity 83% and specificity 76.5%.

Conclusion:

ICD can be used as predictor of difficult needle placement for CEB. USG guidance may be of help while performing CEB in children less than 1.5 years.

Caudal epidural blocks in paediatric patients: a review and practical considerations

Caudal epidural blockade in children is one of the most widely administered techniques of regional anaesthesia. Recent clinical studies have answered major pharmacodynamic and pharmacokinetic questions, thus providing the scientific background for safe and effective blocks in daily clinical practice and demonstrating that patient selection can be expanded to range from extreme preterm births up to 50 kg of body weight. This narrative review discusses the main findings in the current literature with regard to patient selection (sub-umbilical vs mid-abdominal indications, contraindications, low-risk patients with spinal anomalies); anatomical considerations (access problems, age and body positioning, palpation for needle insertion); technical considerations (verification of needle position by ultrasound vs landmarks vs 'whoosh' or 'swoosh' testing); training and equipment requirements (learning curve, needle types, risk of tissue spreading); complications and safety (paediatric regional anaesthesia, caudal blocks); local anaesthetics (bupivacaine vs ropivacaine, risk of toxicity in children, management of toxic events); adjuvant drugs (clonidine, dexmedetomidine, opioids, ketamine); volume dosing (dermatomal reach, cranial rebound); caudally accessed lumbar or thoracic anaesthesia (contamination risk, verifying catheter placement); and postoperative pain. Caudal blocks are an efficient way to offer perioperative analgesia for painful sub-umbilical interventions. Performed on sedated children, they enable not only early ambulation, but also periprocedural haemodynamic stability and spontaneous breathing in patient groups at maximum risk of a difficult airway. These are important advantages over general anaesthesia, notably in preterm babies and in children with cardiopulmonary co-morbidities. Compared with other techniques of regional anaesthesia, a case for caudal blocks can still be made.

Determining the extent of the dural sac for the performance of caudal epidural blocks in newborns

BACKGROUND

Information regarding the position and relationship of vital structures within the caudal canal is important for anesthesiologists who perform a caudal block. This information can be acquired by anatomical dissection, with ultrasound technology, or radiological studies.

AIMS

The aim of this study was to determine the position of the dural sac in neonates by measuring the distance of the termination of the dural sac from the apex of the sacral hiatus in neonatal cadavers.

METHODS

After careful dissection, the distance from the apex of the sacral hiatus to the dural sac was measured in a sample of neonatal cadavers.

RESULTS

In 39 neonatal cadavers, the mean distance from the apex of the sacral hiatus to the dural sac was 10.45 mm. The range of this distance was between 4.94 and 26.28 mm. The mean distance for females was 9.64 mm (range from 6.66 to 15.09); that for males was 10.90 mm (range between 4.94 and 26.28). Linear regression with the log of this distance as the outcome variable gave an estimated 3.3% increase in the distance for each 1 cm increase in the length of the neonate (95% CI for this proportion was 1.91-4.71).

CONCLUSION

Anesthesiologists should be aware of the short distance between the sacral hiatus and the dural sac when performing caudal blocks, the shortest distance was 4.94 mm. Armed with this knowledge, caudal techniques should be modified to improve the safety and reduce the risk of complications, such as dural puncture.

Caudal and epidural blocks in infants and small children: historical perspective and ultrasound-guided approaches

In infants and small children, ultrasound (US) guidance provides ample anatomical information to perform neuraxial blocks. We can measure the distance from the skin to the epidural space in the US image and can refer to it during needle insertion. We may also visualize the needle or a catheter during real-time US-guided epidural catheterization. In cases where direct needle or catheter visualization is difficult, US allows predicting successful puncture and catheterization using surrogate markers, such as dura mater displacement, epidural space widening due to drug injection, or mass movement of the drug within the caudal space. Although many experienced anesthesiologists still prefer to use conventional techniques, prospective randomized controlled trials using US guidance are providing increasing evidence of its advantages. The use of US-guided regional block will gradually become widespread in infants and children.

Ultrasound-guided versus conventional injection for caudal block in children: A prospective randomized clinical study

STUDY OBJECTIVE

The aim of this study was to compare the efficacies of ultrasound guided sacral hiatus injection and conventional sacral canal injection performed for caudal block in children.

DESIGN

Randomized controlled clinical trial.

SETTING

Operating rooms of university hospital of Erzurum, Turkey.

PATIENTS

One hundred-thirty four children, American Society of Anesthesiologists I-II, between the ages of 5 and 12, scheduled for elective phimosis and circumcision surgery.

INTERVENTIONS

Patients assigned to two groups for ultrasound guided caudal block (Group U, n=68) or conventional caudal block (Group C, n=66). Caudal solution was prepared as 0.125% levobupivacaine plus 10mcg/kg morphine (total volume: 0.5ml/kg), and was administered to both groups.

MEASUREMENTS

The block performing time, the block success rate, the number of needle puncture, the success at first puncture and the complications were recorded.

MAIN RESULTS

The block performing time and the success rate of block were similar between Group U and Group C (109.96±49.73s vs 103.17±45.12s, and 97% vs 93%, respectively p>0.05). The first puncture success rate was higher in Group U than in Group C (80% vs 63%, respectively p=0.026). No significant difference was observed between the groups with regard to the number of needle punctures (p=0.060). The rates of vascular puncture and subcutaneus bulging were higher in Group C than in Group U (8/66 vs 1/68, and 8/66 vs 0/68, respectively p<0.05).

CONCLUSIONS

Despite the limitations in central neuroaxial anesthesia we recommend the use of ultrasound since it reduces the complications and increases the success rate of first puncture in pediatric caudal injection.

Regional anaesthesia in neonates, infants and children: an educational review

Prophylactic analgesia with local anaesthesia is widely used in children and has a good safety record. Performing regional blocks in anaesthetised children is a safe and generally accepted practice. When compared with adults, lower concentrations of local anaesthetics are sufficient in children; the onset of a block occurs more rapidly but the duration is usually shorter. Local anaesthetics have a greater volume of distribution, a lower clearance and a higher free (non-protein-bound) fraction. The recommended maximum dose has to be calculated for every individual. Peripheral blocks provide analgesia restricted to the site of surgery, and some of them have a very long duration of action. Abdominal wall blocks, such as transverse abdominis plane or ilio-inguinal nerve block, should be performed with the aid of ultrasound. Caudal anaesthesia is the single most important technique. Ropivacaine 0.2% or levobupivacaine 0.125 to 0.175% at roughly 1 ml  kg⁻¹ is adequate for most indications. Clonidine and morphine can be used to prolong the duration of analgesia. Ultrasound is not essential for performing caudal blocks, but it may be helpful in case of anomalies suspected at palpation and for teaching purposes. The use of paediatric epidural catheters will probably decline in the future because of the potential complications.

Successful use of ultrasound-guided caudal catheter in a child with a very low termination of dural sac and Opitz-GBBB syndrome: a case report

We report a 2-year-old patient with Opitz-GBBB syndrome scheduled for a posterior sagittal anorectoplasty (PSARP). The ultrasound scan revealed the inferior end of dural sac just below sacrococcygeal membrane, although the patient had previously two successful caudal epidural blocks. Consequently, the epidural catheter was inserted under a real-time ultrasound guidance without dural puncture. Our patient had excellent pain relief without any side effects.

Where is the apex of the sacral hiatus for caudal epidural block in the pediatric population? A radio-anatomic study

PURPOSE

Caudal epidural block (CEB), administered through the sacral hiatus, is a regional anesthetic technique commonly used in children. To facilitate and optimize pediatric CEB, morphometric data that may be important for the sacral hiatus have been obtained using multidetector computed tomography (MDCT).

METHODS

This study is the first radio-anatomic study designed to address this topic in children. Images of 79 children (39 girls and 40 boys between 1 and 9 years old) were divided into three groups according to age [group I (ages 1-3), group II (ages 4-6), and group III (ages 7-9)] and were retrospectively examined. Data were gathered via 3D volume-rendered images. Measurements included the height and width of the sacral hiatus, S2-S4 (sacral vertebra) distance, the distances between the poles of the unfused spinous process of each sacral vertebra, and the dimensions of an imaginary triangle formed between the right and left posterior superior iliac spines (PSIS) and the apex of the sacral hiatus.

RESULTS

The most frequently fused spinous process was at S2 level. The mean S2-S4 distance was 1.36 cm for group I, 1.78 cm for group II, and 2.17 cm for group III. There was not the imaginary equilateral triangle used in the method of finding the sacral hiatus for CEB, and the apex of this triangle did not occur at the standard level (S4) in most of the children. It was observed that the apex deriving from the most distal fused spinous process was at the level of S2 in one of two children.

CONCLUSION

Dural puncture is inevitable for CEB applied at the S2 level. Consequently, CEB should be applied below this level (range, 1.36-2.17 cm) from the midpoint of the interspinous distance between the PSIS (at the same level with S2) in children aged 1-9 years.

Ultrasonography reveals a high prevalence of lower spinal dysraphism in children with urogenital anomalies

BACKGROUND

Lower spinal dysraphism is frequently reported in anorectal anomaly combined with urogenital anomalies. The prevalence of the spinal dysraphism has not been comprehensively studied in children with simple urogenital anomalies. We evaluated the prevalence of the spinal dysraphism using ultrasound data of the lumbosacral area in children with urogenital anomalies.

METHODS

Lumbosacral ultrasound images of 259 children who underwent urological surgery with simple urogenital anomalies were reviewed by an ultrasound-specialized radiologist. The primary outcome measures were the conus medullaris (CM) level and the thickness of the filum terminale. The spinal ultrasonographic findings that were assessed in children showed abnormal spinal findings compared with the other children having normal findings. Two years later, the follow-up telephone interviews were made with the parents of the children with abnormal findings.

RESULTS

Eighteen children were differentiated as the abnormal finding group. They were suspected of spinal cord tethering. The level of CM was lower, and the filum terminale was thicker compared to the normal group [L2(lower (L)) vs. L1(L), 2.2 mm vs. 0.8 mm]. Of eighteen children, four were confirmed as tethered spinal cord with lipoma on magnetic resonance imaging by the time of surgery, and two were strongly suspected of occult spinal dysraphism (OSD) based on ultrasound findings and follow-up interviews.

CONCLUSIONS

The prevalence of OSD in children under 24 months of age with simple urogenital anomaly was higher than what was reported for the general population. Ultrasound examination of spinal structures before caudal block in children with urogenital anomaly should be considered.

Caudal blocks

Caudal anesthesia is the single most important pediatric regional anesthetic technique. The technique is relatively easy to learn (1), has a remarkable safety record (2), and can be used for a large variety of procedures. The technique has been reviewed in the English (3) and French (4) literature, as well as in German guidelines (5) and in pediatric anesthesia textbooks (6).