Ultrasound guided catheterisation of the epidural space (interventional procedures consultation)

NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE

Interventional Procedure Consultation Document

Ultrasound-guided catheterisation of the epidural space

Catheterisation of the epidural space (an 'epidural') is a common way of providing pain relief for childbirth or surgery. Ultrasound guidance may be used to help position the tip of the catheter in the correct place, particularly for patients in whom this is difficult.

The National Institute for Health and Clinical Excellence is examining ultrasound-guided catheterisation of the epidural space and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about ultrasound-guided catheterisation of the epidural space.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

comments on the preliminary recommendations
the identification of factual inaccuracies
additional relevant evidence.

Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that the Institute will follow after the consultation period ends is as follows.

The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
The Advisory Committee will then prepare draft guidance which will be the basis for the Institute's guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the Institute's website (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and how it might be improved.

Closing date for comments: 23 October 2007
Target date for publication of guidance: January 2008

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.

1	Provisional recommendations

1.1	Evidence on ultrasound-guided catheterisation of the epidural space is limited in amount, but suggests that ultrasound may be helpful in some patients whose anatomy makes use of the conventional technique (without image guidance) problematic. The use of ultrasound guidance introduces no additional safety concerns to epidural catheterisation. Clinicians who use this technique should therefore do so with normal arrangements for governance and audit. Normal consent should include informing patients about the possibility of rare but serious complications of catheterisation of the epidural space.

The procedure

2.1

Indications

2.1.1

Catheterisation of the epidural space, commonly known as an epidural, is often used to provide pain control during labour or during and after surgery on the abdomen, pelvis or legs.

2.1.2

In some patients, such as those with scoliosis or obesity, it may be more difficult to insert the catheter into the epidural space.

2.1.3

In the conventional procedure, the point of injection is determined by feeling for specific bony landmarks on the spine and pelvis. A small volume of local anaesthetic is injected into the skin and interspinous ligament. A needle is advanced slowly through the interspinous ligament until resistance is no longer felt to the attempted injection of air or saline: this indicates that the tip of the needle is in the epidural space (the 'loss-of-resistance' technique). A catheter is then threaded through the needle into the epidural space, the needle is removed and the catheter is secured.

2.2

Outline of the procedure

2.2.1

Ultrasound guidance may be used in two different ways to facilitate catheterisation of the epidural space. One method is to use real-time ultrasound imaging to observe passage of the needle towards and into the epidural space (real-time ultrasound). The second method (prepuncture ultrasound) is to use ultrasound as a guide to the conventional 'loss-of-resistance' technique. In this method an initial ultrasound scan of the patient?s lumbar spine is performed to locate the midline and the middle of an interspinous space: the position of each is marked on the skin. The depth of the epidural space is also determined by ultrasound. Catheterisation is then done in the conventional way, based on the skin markings.

2.3

Efficacy

2.3.1

The published literature describes the use of this procedure in children and neonates, pregnant women and patients with scoliosis.

2.3.2

In a randomised controlled trial (RCT) of 64 children, comparing real-time ultrasound with prepuncture ultrasound, epidural catheter placement was successful in all children. The epidural procedure took 162 seconds to perform in the real-time ultrasound group compared with 234 seconds in the prepuncture ultrasound group (p less than 0.01). In the prepuncture ultrasound group, supplementary intraoperative analgesia was required by 6% (2/34) of children and postoperative intravenous morphine by 6% (2/34) of children. Neither were required for children in the real-time ultrasound group.

2.3.3

In a case series of 180 children, the epidural space was located on the first puncture attempt in 99.4% (179/180) of cases using prepuncture ultrasound.

2.3.4

In two RCTs (of 300 and 72 pregnant women), comparing prepuncture ultrasound with no ultrasound (control), mean numbers of puncture attempts in the prepuncture ultrasound groups were 1.3 and 1.5 compared with 2.2 and 2.6, respectively, in the control groups (p less than 0.013 and p less than 0.001). In an RCT of 30 pregnant women comparing real-time ultrasound, prepuncture ultrasound and no ultrasound, only one puncture attempt was required in 100% (10/10) of procedures using real-time ultrasound, 70% (7/10) of procedures using prepuncture ultrasound and 40% (4/10) of procedures not using ultrasound (p = 0.036). Patient satisfaction in the RCT of 300 women was significantly higher in the prepuncture ultrasound group than the control group (no ultrasound) (1.3 versus 1.8, measured on a 6-point verbal scale where 1 is very good and 6 is insufficient, p less than 0.001). For more details, refer to the sources of evidence (see appendix).

2.3.5

The Specialist Advisers stated key efficacy outcomes to include patient comfort during catheter insertion, success rate for entering the epidural space at the first attempt, success in patients in whom the conventional technique has failed, identification of the interspinous space by ultrasound and correlation of depth measured by ultrasound with depth on needle insertion.

2.4

Safety

2.4.1

In the RCT of 64 children, aspiration of blood was reported in 3% (1/34) of procedures that used prepuncture ultrasound and in none of the 30 procedures that used real-time ultrasound (p not stated). There were no dural punctures in either group. A case series of 180 children reported that there were no incidents of dural puncture or aspiration of blood using prepuncture ultrasound.

2.4.2

In the RCT of 300 pregnant women, dural puncture was reported in 0.7% (1/150) of patients in the prepuncture ultrasound group compared with 1.3% (2/150) in the control group (not using ultrasound). Aspiration of blood was reported in 2.0% (3/150) of patients in the prepuncture ultrasound group and 7.3% (11/150) of patients in the control group (p not significant). ?Severe? headache was reported in 2.7% (4/150) of patients in the prepuncture ultrasound group and 10.0% (15/150) of patients in the control group (p less than 0.011). There were no significant differences in the rates of reported backache, sensory problems and continence problems. For more details, refer to the sources of evidence (see appendix).

2.4.3

One Specialist Adviser identified an increased risk of accidental dural puncture as a potential adverse outcome if the 'loss-of-resistance' technique is not adhered to.

3	*Further information*
3.1	The Institute has produced technology appraisals guidance on the use of ultrasound locating devices for placing central venous catheters (www.nice.org.uk/TA049).

Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
September 2007

Appendix:

Sources of evidence

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making its provisional recommendations.

'Interventional procedure overview of ultrasound-guided catheterisation of the epidural space', June 2007.

Available from: www.nice.org.uk/ip403overview.

This page was last updated: 30 March 2010