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

Air versus saline in the loss of resistance technique for identification of the epidural space

BACKGROUND

The success of epidural anaesthesia depends on correct identification of the epidural space. For several decades, the decision of whether to use air or physiological saline during the loss of resistance technique for identification of the epidural space has been governed by the personal experience of the anaesthesiologist. Epidural block remains one of the main regional anaesthesia techniques. It is used for surgical anaesthesia, obstetrical analgesia, postoperative analgesia and treatment of chronic pain and as a complement to general anaesthesia. The sensation felt by the anaesthesiologist from the syringe plunger with loss of resistance is different when air is compared with saline (fluid). Frequently fluid allows a rapid change from resistance to non-resistance and increased movement of the plunger. However, the ideal technique for identification of the epidural space remains unclear.

OBJECTIVES

• To evaluate the efficacy and safety of both air and saline in the loss of resistance technique for identification of the epidural space.• To evaluate complications related to the air or saline injected.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 9), MEDLINE, EMBASE and the Latin American and Caribbean Health Science Information Database (LILACS) (from inception to September 2013). We applied no language restrictions. The date of the most recent search was 7 September 2013.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-randomized controlled trials (quasi-RCTs) on air and saline in the loss of resistance technique for identification of the epidural space.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

We included in the review seven studies with a total of 852 participants. The methodological quality of the included studies was generally ranked as showing low risk of bias in most domains, with the exception of one study, which did not mask participants. We were able to include data from 838 participants in the meta-analysis. We found no statistically significant differences between participants receiving air and those given saline in any of the outcomes evaluated: inability to locate the epidural space (three trials, 619 participants) (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.33 to 2.31, low-quality evidence); accidental intravascular catheter placement (two trials, 223 participants) (RR 0.90, 95% CI 0.33 to 2.45, low-quality evidence); accidental subarachnoid catheter placement (four trials, 682 participants) (RR 2.95, 95% CI 0.12 to 71.90, low-quality evidence); combined spinal epidural failure (two trials, 400 participants) (RR 0.98, 95% CI 0.44 to 2.18, low-quality evidence); unblocked segments (five studies, 423 participants) (RR 1.66, 95% CI 0.72 to 3.85); and pain measured by VAS (two studies, 395 participants) (mean difference (MD) -0.09, 95% CI -0.37 to 0.18). With regard to adverse effects, we found no statistically significant differences between participants receiving air and those given saline in the occurrence of paraesthesias (three trials, 572 participants) (RR 0.89, 95% CI 0.69 to 1.15); difficulty in advancing the catheter (two trials, 227 participants) (RR 0.91, 95% CI 0.32 to 2.56); catheter replacement (two trials, 501 participants) (RR 0.69, 95% CI 0.26 to 1.83); and postdural puncture headache (one trial, 110 participants) (RR 0.83, 95% CI 0.12 to 5.71).

AUTHORS' CONCLUSIONS

Low-quality evidence shows that results do not differ between air and saline in terms of the loss of resistance technique for identification of the epidural space and reduction of complications. Applicability might be compromised, as most of the results described in this review were obtained from parturient patients. This review underlines the need to conduct well-designed trials in this field. 

From the Journal archives: Epidural anesthesia in young children: what have we learned in the past 60 years?

Francis G. Ruston MD CITATION: Ruston FG. Epidural anaesthesia in infants and children. Can Anaesth Soc J 1954: 1: 37-44.

PURPOSE

The author describes the use of single-shot epidural anesthesia in a series of 44 infants and children. The patients were anesthetized in hospitals in Hamilton, Ontario from 1949 until the time of publication in 1954. The study aimed to describe the indications and efficacy of this technique as well as any apparent complications. A detailed description of the management of these patients was given, including many tips and suggestions that are still applicable in 2013.

PRINCIPAL FINDINGS

Seventy-seven infants and children received epidural anesthesia for a variety of procedures, particularly for pyloric stenosis. Forty-four of the procedures were carried out by the author. All patients survived, apart from one child who died of recurrent intestinal obstruction unrelated to the anesthetic. It was found, after some experience, that the sitting position was preferable for epidural needle insertion. Use of the hanging drop technique for identification of the epidural space proved to be simple and reliable. Surgical conditions were found to be excellent and relaxation was profound; however, some sedation was often required to obtain optimal conditions for surgery. The surgeons became sold on the technique and began to request an epidural on a regular basis.

CONCLUSIONS

Epidural anesthesia in infants and young children is effective for a variety of procedures below the diaphragm, even in moribund patients.

The Episure Autodetect syringe, a loss-of-resistance technique for locating the epidural space, used in pediatric patients

INTRODUCTION

The Episure Autodetect syringe, a spring-loaded syringe, is a loss-of-resistance syringe with an internal compression that applies constant pressure on the plunger. As the principle of loss-of-resistance is the same for adult and for pediatric patients, the Episure Autodetect syringe should be able to identify correctly the epidural space also in pediatric patients.

METHODS

A retrospective review was carried out for all pediatric patients, in which the Episure Autodetect syringe was used for locating the epidural space between 2007 and 2011 in our department.

RESULTS

In 17 pediatric patients (9 months-14 years, 7.5-43 kg weight), the Episure syringe was used. In all 17 patients, the epidural space was correctly identified using the spring-loaded syringe as evidenced by satisfactory analgesia. No accidental dural punctures or false loss-of-resistances were observed.

CONCLUSION

The spring-loaded Episure Autodetect syringe might be a potentially useful loss-of-resistance syringe for identification of the epidural space in pediatric patients.

Recent developments in paediatric neuraxial blocks

Paediatric anaesthesia and paediatric regional anaesthesia are intertwined. Almost all surgeries unless contradicted could be and should be supplemented with a regional block. The main objective of this review is to elaborate on the recent advances of the central neuraxial blocks, such as application of ultrasound guidance and electrical stimulation in the pursuit of safety and an objective end point. This review also takes account of the traditional technique and understand the benefits as well the risk of each as compared with the recent technique. The recent trends in choosing the most appropriate peripheral block for a given surgery thereby sparing the central neuroaxis is considered. A penile block for circumcision or a sciatic block for unilateral foot surgery, rather than caudal epidural would have a better risk benefit equation. Readers will find a special mention on the recent thoughts on continuous epidural analgesia in paediatrics, especially its rise and fall, yet its unique importance. Lastly, the issue of block placements under sedation or general anaesthesia with its implication in this special population is dealt with. We conducted searches in MEDLINE (PubMed) and assessed the relevance of the abstracts of citations identified from literature searches. The search was carried out in English, for last 10 years, with the following key words: Recent advances in paediatric regional anaesthesia; ultrasound guidance for central neuraxial blocks in children; role of electrical stimulation in neuraxial blocks in children; complications in neuraxial block. Full-text articles of potentially relevant abstracts were retrieved for further review.

Pediatric epidural analgesia (PEA)

The pediatric epidural is an accepted method of advanced analgesia in children. Newer techniques have now superseded pediatric epidural analgesia (PEA), being as effective and safer, especially with the advances in ultrasonography. PEA is, however, still an important technique to master and employ, and it may be that the indications for this mode of analgesia have now become more defined.

Some current controversies in paediatric regional anaesthesia

PURPOSE OF REVIEW

Controversial topics in paediatric regional anaesthesia are discussed.

RECENT FINDINGS

The performance of blocks under general anaesthesia, new local anaesthetics, adjuvants, location techniques, and risks of masking compartment syndromes are contemplated.

SUMMARY

The performance of regional blocks in anaesthetized patients is generally contra-indicated in adults but accepted in children. Levobupivacaine displays the same pharmacokinetic profile as racemic bupivacaine with possibly less cardiac toxicity. Ropivacaine undergoes slower absorption and, in some studies, concomitant increase in peak plasma concentration in infants. Conversely, continuous infusion of ropivacaine offers the safest therapeutic index. Many adjuvants have been used but only epinephrine, clonidine, and preservative-free ketamine offer clear advantages. Midazolam and neostigmine are effective but have potential drawbacks and raise safety questions. Needle and catheter positioning is critical. Electrocardiogram guidance and electrical stimulation occasionally help identify the migration of epidural catheters. Stimulating catheters might be useful for continuous peripheral blockade. Ultrasonography will probably become the reference technique for peripheral catheter placement. Patients at risk of compartment syndrome must be monitored (measurement of compartmental pressures); adequate pain management does not 'hide' this complication but, on the contrary, can facilitate early diagnosis since the increase in requirement for pain medication precedes other clinical symptoms by an average of 7.3 h.