Loss of resistance to saline with a bubble of air to identify the epidural space in infants and children: a prospective study

Intramedullary pneumorrhachis following a cervical epidural steroid injection

Pneumorrhachis (PR) is a rare radiological condition characterized by the presence of intraspinal air. PR is commonly classified as spontaneous (nontraumatic), traumatic, or iatrogenic, and iatrogenic PR is the most common and often occurs secondary to invasive procedures such as epidural anesthesia, lumbar puncture, or spinal surgery. PR is usually asymptomatic, but it can produce symptoms associated with its underlying pathology. Here, we report a rare case of intramedullary cervical PR following a cervical epidural steroid injection (ESI) and include pertinent discussion.

Identification of epidural space using loss of resistance syringe, infusion drip, and balloon technique: A comparative study

BACKGROUND AND OBJECTIVE

There are various techniques to identify epidural space but superiority of one technique over other has not been adequately studied. We conducted a study to Compare and evaluate the three techniques for epidural space localization that is, loss of resistance (LOR) syringe technique, balloon technique and drip infusion technique.

MATERIALS AND METHODS

Seventy-five patients of either sex, belonging to American Society of Anesthesiologists physical status Class 1 or 2, between 20 and 50 years of age, scheduled to undergo lower abdominal and lower limb surgeries were randomly allocated to one of the three groups (n = 25 each) depending upon epidural space localization. In Group I, epidural space localization was done with LOR syringe technique. In Group II Balloon technique and in Group III drip infusion technique was used. Distance of the epidural space from skin, number of attempts, time taken for epidural space localization and quality of the block were the parameter recorded during the study.

RESULTS

First attempt success rate for epidural space localization was highest in Group III (100%). The mean time taken for epidural space localization was least in Group III, and when compared with other groups it was found to be statistically significant with P = 0.016. Number of attempt for space localization and success rate of the block was better in the majority of patients of Group III, but the difference was found to be statistically nonsignificant. Complication rate was almost negligible in all three techniques.

CONCLUSION

We conclude that the time taken to localize the epidural space was least in drip infusion technique. As for number of attempts, quality of the block and complications is concerned, all the three techniques are comparable.

Controversial issues in pediatric regional anesthesia

Regional anesthesia in children has reached in the last decades a widespread approval and today is a valid and effective technique used in the daily activity in many pediatric centres. Data from surveys and studies show the very low rate of complications and suggest that the use of regional techniques in children is at least as safe as general anesthesia alone. Despite these evidences there are aspects still creating discussions on the best approach to avoid or prevent risks and on the way to make this techniques more and more reliable and safe. Compartment syndrome, test dose, loss-of-resistance technique and blocks performed under general anesthesia are examples of, sometimes, never-ending stories; this review without the presumption to solve every problem shows the more recent data to offer, if possible, the best updated-answer on these topics.

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.

Compressed air injection technique to standardize block injection pressures

PURPOSE

Presently, no standardized technique exists to monitor injection pressures during peripheral nerve blocks. Our objective was to determine if a compressed air injection technique, using an in vitro model based on Boyle's law and typical regional anesthesia equipment, could consistently maintain injection pressures below a 1293 mmHg level associated with clinically significant nerve injury.

METHODS

Injection pressures for 20 and 30 mL syringes with various needle sizes (18G, 20G, 21G, 22G, and 24G) were measured in a closed system. A set volume of air was aspirated into a saline-filled syringe and then compressed and maintained at various percentages while pressure was measured. The needle was inserted into the injection port of a pressure sensor, which had attached extension tubing with an injection plug clamped "off". Using linear regression with all data points, the pressure value and 99% confidence interval (CI) at 50% air compression was estimated.

RESULTS

The linearity of Boyle's law was demonstrated with a high correlation, r = 0.99, and a slope of 0.984 (99% CI: 0.967-1.001). The net pressure generated at 50% compression was estimated as 744.8 mmHg, with the 99% CI between 729.6 and 760.0 mmHg. The various syringe/needle combinations had similar results.

CONCLUSION

By creating and maintaining syringe air compression at 50% or less, injection pressures will be substantially below the 1293 mmHg threshold considered to be an associated risk factor for clinically significant nerve injury. This technique may allow simple, real-time and objective monitoring during local anesthetic injections while inherently reducing injection speed.

Effects of epidural administration of morphine and buprenorphine on the minimum alveolar concentration of isoflurane in cats

OBJECTIVE

To determine effects of epidural administration of morphine and buprenorphine on the minimum alveolar concentration of isoflurane in cats. Animals-6 healthy adult domestic shorthair cats.

PROCEDURES

Cats were anesthetized with isoflurane in oxygen. Morphine (100 microg/kg diluted with saline [0.9% NaCl] solution to a volume of 0.3 mL/kg), buprenorphine (12.5 microg/kg diluted with saline solution to a volume of 0.3 mL/kg), or saline solution (0.3 mL/kg) was administered into the epidural space according to a Latin square design. The minimum alveolar concentration (MAC) of isoflurane was measured in triplicate by use of the tail clamp technique. At least 1 week was allowed between successive experiments.

RESULTS

The MAC of isoflurane was 2.00 +/- 0.18%, 2.13 +/- 0.11%, and 2.03 +/- 0.09% in the morphine, buprenorphine, and saline solution groups, respectively. No significant difference in MAC was detected among treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

A significant effect of epidural administration of morphine or buprenorphine on the MAC of isoflurane in cats could not be detected. Further studies are needed to establish whether epidural opioid administration has other benefits when administered as a component of general anesthesia in cats.

Pneumorrhachis following lumbar puncture: a case report

We report a rare case of pneumorrhachis following lumbar puncture. A 4-year-old boy was admitted to our hospital with seizures following a head injury and upper respiratory infection. Lumbar puncture was performed to rule out central nervous system infection. In response to leg pain and weakness a few hours after the procedure, lumbar spine computed tomography (CT) revealed pneumorrhachis at the level of L5-S1. In a follow-up CT scan 3 days later, the pneumorrhachis resolved spontaneously. Pneumorrhachis following diagnostic lumbar puncture is an extremely rare condition. We discuss pneumorrhachis and review cases in the literature.

Loss of resistance to normal saline is preferred to identify the epidural space: a survey of Canadian pediatric anesthesiologists

PURPOSE

Several methods have been described to locate the epidural space, but the loss-of-resistance (LOR) technique is the most commonly used. Expert opinion states that LOR to air is the best medium for neonates and infants. We conducted a Canada-wide postal survey to determine the current state of practice for placement of epidural catheters in pediatric patients.

METHODS

Two hundred and nine surveys were distributed to academic pediatric anesthesiologists across Canada. The survey was limited to six questions and was anonymous.

RESULTS

The response rate was 62.2%. LOR was the method of choice for 124/130 anesthesiologists (95.4%). LOR to normal saline was the medium of choice for all age groups, although LOR to air and LOR to air/saline gained in popularity with increasing patient age. The majority of anesthesiologists do not change their LOR technique for different patient ages or level of epidural insertion. Most responders ranked 'training' as the most important determinant of practice, whereas 'departmental guidelines' were considered the least important. No complication attributable to the LOR technique used was reported.

CONCLUSION

LOR to normal saline is the preferred method for identification of the epidural space in children of all age groups. The suggestion by experts that LOR to air should be used in neonates and infants was not supported by the practice of pediatric anesthesiologists across Canada.

Epidural analgesia in veterinary critical care

Epidural analgesia has minimal systemic effects and is a useful technique for relieving pain in critical care patients. Before administration, patients must be thoroughly assessed to identify any preexisting conditions that preclude the safe use of this technique. Analgesia can be achieved by administration of local anesthetics, opioids, alpha 2 agonists, or a combination of these analgesic agents. Concurrent administration of more than one drug allows the synergistic interaction of these agents and generally improves the level of analgesia achieved, lengthens the duration of action, and lowers the dose of each drug required to achieve analgesia. Complications of epidural techniques are infrequent and include both iatrogenic and idiopathic problems, most of which have no permanent sequelae. This review provides a detailed description of the epidural analgesia technique and lists multiple sources of specialized supplies necessary for either single injection or epidural catheter placement. It also provides direction for monitoring the critical care patient with an epidural catheter.