Thoracic epidural analgesia via the caudal approach using nerve stimulation in an infant with CATCH22

Visceral versus somatic pain: an educational review of anatomy and clinical implications

Somatic and visceral nociceptive signals travel via different pathways to reach the spinal cord. Additionally, signals regulating visceral blood flow and gastrointestinal tract (GIT) motility travel via efferent sympathetic nerves. To offer optimal pain relief and increase GIT motility and blood flow, we should interfere with all these pathways. These include the afferent nerves that travel with the sympathetic trunks, the somatic fibers that innervate the abdominal wall and part of the parietal peritoneum, and the sympathetic efferent fibers. All somatic and visceral afferent neural and sympathetic efferent pathways are effectively blocked by appropriately placed segmental thoracic epidural blocks (TEBs), whereas well-placed truncal fascial plane blocks evidently do not consistently block the afferent visceral neural pathways nor the sympathetic efferent nerves. It is generally accepted that it would be beneficial to counter the effects of the stress response on the GIT, therefore most enhanced recovery after surgery protocols involve TEB. The TEB failure rate, however, can be high, enticing practitioners to resort to truncal fascial plane blocks. In this educational article, we discuss the differences between visceral and somatic pain, their management and the clinical implications of these differences.

Prediction of Successful Epidural Catheter Placement by a ‘Cold Test’

We tested the hypothesis that the patients’ feeling of cold sensation down the back during epidural drug administration through the epidural catheter was a reliable predictor of correct epidural catheter placement. In a prospective study of 80 patients, an epidural catheter was placed in the lumbar epidural space. During epidural drug injection, patients were asked to report feeling of the cold sensation in their back by pressing a bell. After 15 minutes, the patients were assessed for cold sensation in the thoracic to sacral dermatomes bilaterally and the dermatomal block recorded. Of 80 patients, three had inadvertent dural puncture. Seventy-two of 77 patients reported feeling cold sensation in their back during local anaesthetic injection, and all had successful epidural blockade. Of the five patients who did not report any cold sensation, three had failed epidural block and two successful epidural block. There were no false positive results. Of three patients who had inadvertent dural puncture and had normal saline 5 ml injected through the Tuohy needle, none reported cold sensation. The perception of cold sensation in the back during epidural administration of a test dose and/or subsequent full dose of local anaesthetic is useful in predicting successful epidural catheter placement.

Stimulating thoracic epidural placement via a lumbar approach causes significant spinal cord damage in a porcine model

BACKGROUND

Continuous thoracic epidural analgesia is a valuable and common technique for analgesia but involves risk to the spinal cord. There is significant pediatric experience safely placing thoracic epidurals via a caudal approach. The use of a stimulating catheter offers the advantage of real-time confirmation of appropriate catheter placement. We hypothesize that the tip of a stimulating epidural catheter can be reliably advanced to the thoracic epidural space with lumbar insertion in a porcine model.

METHODS

This prospective experimental porcine study evaluated the feasibility of placing the tip of a stimulating epidural catheter to a predefined thoracic epidural location after percutaneous lumbar epidural access in six live pigs. After the lumbar epidural space was accessed, a stimulating epidural catheter was advanced until the targeted thoracic myotome was stimulated. The final position of the catheter in relation to the targeted location was determined by fluoroscopy. All animals were euthanized at the end of the experiment, necropsy and spinal cord histology were then performed to assess the extent of spinal cord damage.

RESULTS

In all animals the epidural catheter tip could be accurately advanced to the targeted thoracic myotome. Gross subdural bleeding occurred in three of the six animals and deep spinal damage was observed in two of the six animals. In one animal, the catheter was placed in the subarachnoid space.

CONCLUSIONS

Accurate access to the thoracic epidural space is possible via a lumbar approach using a stimulating epidural catheter. Based on gross and histopathological examination, this technique resulted in frequent complications, including subdural hemorrhage, deep spinal cord damage, and subarachnoid catheter placement.

Pediatric pain management

Regional anesthesia has become an integral part of adult anesthesia. Although not routinely used in children because of the need for general anesthesia that is necessary to keep the patients from moving and cooperating with the operator, regional anesthesia has been gaining immense popularity in the last decade. Although there is not much objective evidence, large prospective databases and expert opinion have favored administering regional anesthesia in the asleep child safely because major neural damage has not been reported in children. This review discusses a comprehensive approach to acute pain management in infants, children, and adolescents using regional anesthesia.

New insights into regional anesthesia in children: new techniques and new indications

The applications and indications for pediatric regional anesthesia continue to increase. Several recent advances have occurred in the understanding of this technology in children, including improved techniques, alternative drug combinations, as well as prospective investigations to understand the nature and incidence of adverse effects associated with these techniques when used in pediatric patients. The following article will review recent information from the literature concerning various regional anesthetic techniques in children, including caudal epidural block, lumbar and thoracic epidural anesthesia, and peripheral nerve blockade.

Innovative approaches to neuraxial blockade in children: the introduction of epidural nerve root stimulation and ultrasound guidance for epidural catheter placement

Continuous epidural blockade remains the cornerstone of pediatric regional anesthesia. However, the risk of catastrophic trauma to the spinal cord when inserting direct thoracic and high lumbar epidural needles in anesthetized or heavily sedated pediatric patients is a concern. To reduce this risk, research has focused on low lumbar or caudal blocks (ie, avoiding the spinal cord) and threading catheters from distal puncture sites in a cephalad direction. However, with conventional epidural techniques, including loss-of-resistance for localization of the needle, optimal catheter tip placement is difficult to assess because considerable distances are required during threading. Novel approaches include electrical epidural stimulation for physiological confirmation and segmental localization of epidural catheters, and ultrasound guidance for assessing related neuroanatomy and real-time observation of the needle puncture and, potentially, catheter advancement. The present article provides a brief and focused review of these two advances, and outlines recent clinical experiences relevant to pediatric epidural anesthesia.

Imaging techniques for regional nerve blockade and vascular cannulation in children

PURPOSE OF REVIEW

This review identifies the most serious complications likely to be encountered in the current practice of paediatric anaesthesia.

RECENT FINDINGS

The findings of the ASA Closed Claims Project, published in 1993, showed a higher proportion of closed paediatric malpractice claims related to respiratory events than to cardiovascular events. The Pediatric Perioperative Cardiac Arrest Registry--an offshoot of the American Society of Anesthesiologists Closed Claims Project--reviewed cardiac arrest data collected between 1994 and 1997, revealing a shift in the aetiology of cardiac arrest during paediatric anaesthesia over the past 20 years. The study found that reported cardiac arrests were now more prevalent from cardiovascular causes than respiratory causes, unlike the findings in the previous Closed Claims Project. Follow-up data collected by both the Pediatric Perioperative Cardiac Arrest Registry and the American Society of Anesthesiologists Closed Claims Project confirm this trend.

SUMMARY

Outcomes for paediatric patients undergoing anaesthesia have improved over the years as a result of advances in monitoring and equipment, safer and more easily titratable anaesthetic agents, and possibly the practice of subspecialization. Preventable complications still, however, occur. An awareness of frequently encountered complications during paediatric anaesthesia may lead to the earlier detection and treatment of perioperative problems, leading to better outcomes.

Anesthetic management of a child with chromosome 22q11 deletion syndrome

Chromosome 22q11 deletion syndrome (22q11DS) is a congenital anomaly characterized by cardiovascular, oropharyngeal, immunologic, endocrine, and neurodevelopmental abnormalities. We successfully managed a 6-year-old girl with 22q11DS with general anesthesia. Potential problems in anesthetic management of patients with 22q11DS are reviewed.

Inadvertent cervical epidural catheter placement via the caudal route using electrical stimulation

Inadvertent placement of an epidural catheter in the cervical region via the caudal route is described in an infant who underwent revision of a fundoplication. We attempted electrical stimulation (the Tsui test) via the epidural catheter to confirm correct placement and positioning of the catheter tip. In this case, the epidural catheter was inadvertently advanced to the cervical region, resulting in stimulation of the phrenic nerve. These diaphragmatic twitches were misinterpreted as chest wall twitches, and it was incorrectly assumed that the catheter was in the thoracic region. To avoid misinterpretation of the stimulation level, the catheter should be continuously stimulated while it is advanced. We also recommend that the catheter length be estimated before insertion (although doing so did not help in this case) and that the catheter position be radiographically confirmed after surgery.

Thoracic epidural catheter placement via the caudal approach in infants by using electrocardiographic guidance

We examined the success of inserting epidural catheters via the caudal route in infants by using electrocardiographic guidance. A case series of 20 patients with thoracic epidural analgesia was studied. After the induction of general anesthesia, an 18-gauge IV catheter was inserted into the caudal space to allow threading of a 20-gauge epidural catheter. The electrocardiogram (ECG) tracings via the epidural catheter, as well as the surface ECG at the target spine level, were recorded simultaneously with a modified two-channel five-lead ECG system. The epidural catheter was advanced from the caudal space until the tip reached the target level as demonstrated by a match in the configuration of the epidural ECG tracing to that of the surface ECG tracing at the target level. The catheter tip location was verified by postoperative radiographs. All catheter tips were located within two vertebrae of the target level, and satisfactory intraoperative epidural anesthesia was achieved in all subjects.

IMPLICATIONS

Epidural electrocardiography may be used to guide the positioning of the thoracic epidural catheter tip via the caudal approach to the appropriate dermatome for optimum analgesia.

The caudal catheter in neonates: where are the restrictions?

PURPOSE OF REVIEW

In neonates, epidural catheters inserted at the sacral hiatus can easily be advanced to a lumbar or thoracic level. These 'caudal catheters' are popular because they allow the neonate to benefit from epidural analgesia without the concerns of spinal cord injury potentially associated with primary thoracic placement in an asleep neonate. This review looks at use and benefits, and risks and complications of caudal epidural catheters in neonates.

RECENT FINDINGS

Restrictions of neonatal caudal catheters are related to risks associated with placement and advancement of the catheters, infectious risks of caudal catheters, and toxicity risks related to the higher free fraction and lower clearance of bupivacaine in neonates. Caudal catheters in neonates are popular, but evidence that they improve outcome is lacking.

SUMMARY

Epidural anesthesia and analgesia for neonates should be performed and managed by pediatric anesthesiologists. Potential risks and complications must be appreciated and all steps to maximize safety of the technique must be taken. In particular, close postoperative observation and pain service management are indispensable. Future research should investigate the risks of caudal and segmentally placed catheters in neonates, study the role of epidural analgesia in outcome improvement for neonates, and guide us to safer use of local anesthetics suitable for neonates with their pharmacologic immaturity.

New concepts in acute and extended postoperative pain management in children

Increased knowledge of the pathophysiology of pain in children and an improved understanding of the pharmacology and pharmacodynamics of multiple agents have provided the clinician with a wide variety of tools to treat postoperative pain in children. The interest in a multimodal approach is kindled by the realization that the combination of a number of therapies can enhance analgesia with fewer untoward side effects. The expertise of other health care professionals should be tapped to open new avenues of treatment. Many therapies still require critical evidence-based evaluations to assess how well they work in larger patient populations. Dedication to research, compassionate patient care, and a willingness to teach the next generation of clinicians will bring us closer to the goal of safe and pain-free surgery.

Practical pediatric regional anesthesia

In children, regional anesthetic techniques are safe and effective adjuncts to general anesthesia and for postoperative pain relief. Application of the techniques described in this article will contribute to improved care for pediatric patients undergoing surgical procedures. The judicious choice of local anesthetics, along with the blockades of targeted nerves, decrease the need for supplemental analgesics in the recovery phase.

Thoracic epidural analgesia via the caudal approach in pediatric patients undergoing fundoplication using nerve stimulation guidance

IMPLICATIONS

Epidural catheter placement using electrical stimulation guidance is an alternative approach for positioning the catheter into the thoracic region via the caudal space. This easily performed clinical assessment provides optimization of catheter tip positioning for achieving effective pain control.

Thoracic epidural anesthesia for bilateral reduction mammoplasty in a patient with Klippel-Feil syndrome

General anesthesia is best avoided in cases of Klippel-Feil syndrome where tracheal intubation is potentially difficult. The syndrome features severe abnormalities of the neck and upper thoracic spine, which may also lead to difficulties with neuraxial blockade. We describe the use of epidural anesthesia for bilateral reduction mammoplasty in a patient with this condition.