Advice

Technology overview

Technology overview

This briefing describes the regulated use of the technology for the indication specified, in the setting described, and with any other specific equipment referred to. It is the responsibility of health care professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

CE marking

The Epidrum is a class I medical device that received a CE mark in January 2008. The CE mark is held by the manufacturer, Exmoor Plastics.

Description

The Epidrum is a single‑use device designed to provide the user with a clear, visual signal that the epidural needle has entered the epidural space.

The Epidrum is formed from a cylindrical tube with sealed ends, which creates a chamber. It is made from medical grade polymers. The seal on the top end of the tube is an expandable membrane (the diaphragm), which deflates when the epidural needle enters the epidural space (figure 1). There are 2 ports, placed opposite each other in the walls of the cylinder. The inlet port (a female luer), containing a non‑return valve, connects with a syringe and the outlet port (a male luer) connects with an epidural needle.

The Epidrum device

Figure1: The Epidrum device attached to an epidural needle with the diaphragm inflated before entering the epidural space (left) and deflated upon entry (right)

The Epidrum functions as follows:

  • The user inserts the tip of the epidural needle through the skin and into tissue. Air is drawn into a pre‑connected 5‑ml luer syringe, and 1 ml of air is injected into the cylinder, thereby inflating the diaphragm. The non‑return valve ensures that air remains inside the device.

  • Users may need to 'top up' the volume of air in the chamber, which can hold a maximum of 3 ml. The clinician will decide on the amount of air to be injected into the chamber depending on the size and weight of the person having the epidural, and whether any air leakage into the tissues occurs.

  • The epidural needle is then pushed between 2 spinal vertebrae, through the supraspinous ligament, towards the epidural space.

  • When the epidural needle tip enters the epidural space the diaphragm deflates, signalling to the user that the needle is in the epidural space.

The current version of the Epidrum can only be used with standard 16‑ and 18‑gauge epidural needles (smaller gauge numbers indicate larger needle diameters). The manufacturer is developing a version for use with 20‑gauge needles but no indication has been given as to when this will be available. The use of small‑gauge epidural needles may be associated with reductions in post‑dural puncture headaches and haematoma formation (Cook et al. 2009).

Intended use

The Epidrum is intended to help trained clinicians access the epidural space to administer epidural medication. The use of the Epidrum has been developed to correctly identify the epidural space in adults. According to the manufacturer, any use on small children is at the discretion of the clinician (Exmoor Plastics 2013).

Setting and intended user

The Epidrum is intended for use in secondary care settings, specifically in anaesthetic rooms or maternity units with the equipment and staff expertise to conduct procedures that need direct access to the epidural space. The intended user is most likely to be an anaesthetist trained in epidural administration procedures.

Current NHS options

Epidural anaesthesia can be administered as a single injection for short‑term pain relief. If longer‑term pain relief is needed, a catheter is inserted into the epidural space so that continuous or intermittent bolus anaesthesia or analgesia can be given for hours or days (NHS Choices 2013). Currently, epidurals are performed using either 16‑ or 18‑gauge needles.

Lower back and radicular pain is managed with a single lumbar epidural steroid injection (Royal College of Anaesthetists 2014b). Continuous epidural anaesthesia is prescribed for pain relief during childbirth (natural and caesarean sections) and during or after thoracic, abdominal, pelvic or lower limb day‑surgery procedures (where a patient is admitted and discharged home on the same day). NICE's clinical guideline on intrapartum care recommends the use of either epidural or combined spinal–epidural analgesia for regional analgesia in labour. When rapid analgesia is needed, combined spinal–epidural analgesia with bupivacaine and fentanyl is recommended. Either patient‑controlled epidural analgesia or intermittent boluses given by healthcare professionals are preferred for epidural analgesia maintenance.

Depending on the administration method, the standard LOR technique can be complemented with imaging techniques. Fluoroscopy is recommended for single epidural steroid injections (Royal College of Anaesthetists 2014b). Ultrasound imaging should be available for day‑surgery procedures (Royal College of Anaesthetists 2014c) and for all epidural procedures in maternity cases (Royal College of Anaesthetists 2014d). According to NICE interventional procedures guidance, ultrasound-guided catheterisation of the epidural space is safe and may be helpful in achieving correct placement, and may be used provided that normal arrangements are in place for clinical governance, consent and audit. Ultrasound imaging can be used to either guide the epidural needle into the epidural space (in real‑time) or provide information on the regional anatomy before inserting the epidural needle into the epidural space (prepuncture ultrasound).

NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to the Epidrum:

  • the Episure AutoDetect LOR syringe (Indigo Orb)

  • the Epimatic (Vygon).

Costs and use of the technology

The manufacturer states that the Epidrum is available in packs of 10 or 100. The cost of a pack of 10 is £72 (£7.20 per unit) and of a pack of 100 is £570 (£5.70 per unit), excluding VAT. The manufacturer has stated that further bulk discounts are likely; for example, if a hospital purchases more than 800 units per month, the cost will be £4.85 per unit, excluding VAT.

The Epidrum is a single‑use device. Since the Epidrum is used with a luer syringe and an epidural needle (£3.82 per unit [syringe and needle] excluding VAT; prices available on the NHS supply chain), the highest cost of treatment is estimated to be £11.02 per procedure. By comparison, a conventional LOR syringe and epidural needle costs £6.15 per unit (syringe and needle), excluding VAT (prices available from NHS supply chain). Ultrasound‑guided catheterisation of the epidural space is assumed to have a similar cost to an ultrasound scan used in anaesthetics. The relevant NHS reference cost of an ultrasound scan lasting less than 20 minutes in anaesthetics (NHS reference cost 2012–13 code RA23Z) is £18 (Department of Health 2013).

The manufacturer does not offer formal training, but a free demonstration kit is provided to ensure that clinicians can practice the use of the device before using it on patients.

Likely place in therapy

The Epidrum would be used in place of the current LOR syringe for aiding access to the epidural space whenever drugs are indicated to be administered by epidural injection or infusion. It would not replace image‑guided placement when this is otherwise clinically indicated.

Specialist commentator comments

According to one specialist commentator the conventional LOR technique is a reliable method for identifying the epidural space. They noted the difference in the way that pressure is applied to the needle when using the conventional LOR technique compared with the Epidrum. In conventional LOR techniques, the air or saline is unable to leave the tip of the needle until the needle enters the epidural space. When the tip of the needle enters the epidural space, firstly the air or saline is forced out, pushing the dura further from the tip of the needle, and secondly the advancing plunger absorbs any forward force on the needle, allowing the needle to stop moving immediately. These 2 factors reduce the risk of dural puncture, but would not happen when using the Epidrum instead of conventional LOR techniques. The commentator remarked that when using the Epidrum, pressure is applied directly to the needle. As the needle passes through tissue of different resistance it may move forward in an uncontrolled manner, passing through the epidural space and puncturing the dura.

One specialist commentator noted that the Epidrum is very useful for teaching purposes. A major problem that trainees face is successfully advancing the epidural needle while at the same time maintaining constant pressure on the syringe. The Epidrum solves this problem by allowing trainees to use both hands to handle the syringe and advance the needle. The same specialist commentator stated that the epidural procedure is more technically challenging in patients with 'soft' dura, for example pregnant women and people with obesity. In these cases, the Epidrum provides a clear signal that the needle has been inserted into the epidural space.

According to 2 specialist commentators, ultrasound and fluoroscopy may provide anatomical information that will help identify the desired location of the epidural catheter and help avoid damaging nearby tissues. However, their use is complementary to the Epidrum which provides clear confirmation that the needle has reached the epidural space. One specialist commentator stated that ultrasound is useful in identifying the midline in people who are considered to be morbidly obese, people with spinal deformity or people who have previously had spinal surgery.

Two specialist commentators noted that the choice of administration method (single injection or continuous infusion) will not impact on the method used to identify the epidural space. Another specialist commentator noted that the time taken to identify the epidural space, either with the Epidrum or using the conventional LOR technique, is minimal compared to the time taken for the overall procedure (approximately 20 minutes).

One specialist commentator stated that it is uncommon for epidurals to be performed with an epidural needle smaller than 18‑gauge, even in very small children. Another specialist commentator stated that there is no robust evidence to support an association between the use of smaller gauge needles and fewer complications during epidural anaesthesia. One specialist commentator noted that a possible reduction of post‑dural puncture headaches (PDPH) and haematoma formation with smaller‑gauge needles, as mentioned in Cook et al. (2009), is most likely referring to the use of spinal needles to perform spinal anaesthetics. Another specialist commentator noted that factors such as patient positioning, patient movement and clinician's experience are more likely to affect the incidence of dural puncture than the size of the epidural needle. However, a dural puncture caused by a larger epidural needle will result in a higher incidence of PDPH symptoms (up to 70% of patients). The same specialist commentator also noted that in cases of combined spinal–epidural anaesthesia, smaller needles (27‑gauge) or modified epidural needles, such as the Espocan, may reduce the incidence of PDPH (Landau et al. 2001, Browne et al. 2005, Morley‑Forster et al. 2006).

Equality considerations

NICE is committed to promoting equality and eliminating unlawful discrimination. We aim to comply fully with all legal obligations to:

  • promote race and disability equality and equality of opportunity between men and women

  • eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief, in the way we produce our guidance (these are protected characteristics under the Equality Act 2010).

The Epidrum would be used for epidural anaesthesia in intrapartum care. Pregnancy and maternity are protected characteristics defined in the Equality Act 2010.