Advice
Evidence review
Evidence review
Clinical and technical evidence
Regulatory bodies
A search of the Medicines and Healthcare Products Regulatory Agency (MHRA) website revealed no manufacturer Field Safety Notices or Medical Device Alerts for this equipment. No reports of adverse events were identified from searches of the US Food and Drug Administration (FDA) Manufacturer and User Device Facility Experience (MAUDE) database.
Clinical evidence
Four studies providing information on the Epidrum were identified, of which 2 randomised controlled trials were selected to summarise in the briefing. One in‑vitro randomised controlled cross‑over study (Roberts et al. 2010) and 1 randomised controlled trial (Hasan et al. 2010) comparing the Epidrum to the conventional LOR technique were not included in this briefing as they were only published as abstracts.
The randomised controlled trial by Kim et al. (2012) investigated the efficacy and safety of the Epidrum (n=54) compared with the conventional LOR air method (n=54) in people who were scheduled to have gynaecological or orthopaedic surgery under combined spinal–epidural anaesthesia. The study was powered to detect a 20% reduction of procedural time (primary outcome) compared with the conventional technique. The time (mean±SD) to identify the epidural space (measured from the interspinal ligament to the epidural space) with the conventional method was 30±10 seconds. In both groups, the procedure was done by an experienced trainee anaesthetist with an 18‑gauge epidural (Tuohy) needle inserted using a midline approach. Using the Epidrum reduced the mean procedural time by approximately 13 seconds. Analysis of secondary outcomes found significant differences in failure rates, multiple attempts, ease of identification (for both the operator and observer) and satisfaction scores (operators) in favour of the Epidrum group. A summary of these results is reported in tables 1 and 3.
The randomised trial by Sawada et al. (2012) investigated the efficacy and safety of the Epidrum (n=40) compared with conventional LOR techniques (n=40) in people who were scheduled for epidural anaesthesia. The primary outcome was the procedural time in comparison with the conventional techniques. The time needed to identify the epidural space was defined as the time from the skin perforation until the needle penetrated the epidural space. In both groups, the procedure was done by a trainee anaesthetist. No information was provided on the size of the epidural needle or the approach used. The use of the Epidrum reduced the mean procedural time by approximately 60 seconds. Analysis of secondary outcomes found statistically significant improvement in the operator's experience of controlling the epidural needle in the Epidrum group. There was no statistically significant difference between the 2 groups in certainty of epidural space identification as measured by clinical judgement. A summary of these results is reported in tables 2 and 3.
Table 1 Overview of the Kim et al. (2012) randomised controlled trial
|
Study component |
Description |
|
Objectives/hypotheses |
To investigate the efficacy and safety of the Epidrum in comparison with the conventional LOR air technique for identifying the epidural space. |
|
Study design |
Single‑centre randomised controlled trial. |
|
Setting |
A Korean centre. This study did not state a recruitment period. The study did not state a follow‑up period. |
|
Inclusion/exclusion criteria |
Inclusion:
Exclusion:
|
|
Primary outcomes |
Primary:
Secondary:
|
|
Statistical methods |
Descriptive statistics expressed as mean±SD, median and interquartile range. A sample size of n=45 people per group was calculated as adequate to identify a 20% reduction in the time needed to identify the epidural space in the Epidrum group compared to that of the control group, with an alpha error of 0.05 and a power of 80%. The Kolmogorov–Smirnov test was used to test normality. Normally distributed data were compared using independent t‑tests. Non‑normally distributed data were compared using the Mann–Whitney U‑test. The number of people between groups was compared with a chi‑square test. Significance was set at the 0.05 level. |
|
Participants |
The Epidrum (ED) group: 54 participants; age = 45±1.3 years, 15 men and 39 women, mean height 162.1±8.8 cm and mean weight = 62.3±10.2 kg. Conventional LOR (C) group: 54 participants; mean age 45.4±10.4 years, 16 men and 38 women, mean height 162.5±8 cm and mean weight 63.5±10.5 kg. No significant difference existed between the study groups for the above characteristics. |
|
Results |
The number of failures and the number of attempts more than 2 were significantly reduced with the ED group, p=0.022 and p=0.002 respectively. Time taken to identify the epidural space was significantly reduced with the ED group, p<0.001. Ease of performance (both operator and observer) and satisfaction scores were significantly higher with ED group, p<0.001, p<0.001 and p<0.001 respectively. One dural puncture occurred which was associated with group C. No other significant differences existed between the 2 groups. |
|
Conclusions |
The use of the Epidrum reduced the time needed to identify the epidural space. |
|
Abbreviations: ASA, American Society of Anaesthesiologists; C group, conventional loss of resistance techniques group; CSE, combined spinal–epidural; ED, Epidrum; LOR, loss of resistance; SD, standard deviation. |
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Table 2 Overview of the Sawada et al. (2012) randomised controlled trial
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Study component |
Description |
|
Objectives/hypotheses |
To investigate the efficacy and safety of the Epidrum in comparison with the conventional LOR air or saline techniques for identifying the epidural space. |
|
Study design |
Single‑centre randomised controlled trial. |
|
Setting |
A Japanese centre. This study did not state a recruitment period. The study did not state a follow‑up period. |
|
Inclusion/exclusion criteria |
Inclusion:
Exclusion:
|
|
Primary outcomes |
Primary:
Secondary:
|
|
Statistical methods |
Descriptive statistics were expressed as mean±SD or median with IQR. The unpaired t‑test was used to compare interval data when normally distributed. The Mann–Whitney U‑test was used to compare ordinal data. Significance was set at the 0.05 level. |
|
Participants |
The Epidrum group: 40 participants; mean age 54.3±18.2 years, 15 men and 25 women, mean height 157.7±8.0 cm and mean weight 55.7±9.7 kg. Epidural position: T11/12=10, T12/L1=25, L1/L2=4 and L2/3=1. Control group: 40 participants; mean age 51.7±15.9 years, 16 men and 24 women, mean height 159.3±7.7 cm and mean weight 57.2±11.0 kg. Epidural position: T11/12=11, T12/L1=21, L1/L2=6 and L2/3=2. No significant difference existed between the study groups for the above characteristics. |
|
Results |
Time taken to identify the epidural space was significantly reduced in the Epidrum group: median 28 seconds (IQR 10–76) compared with median 90 seconds (IQR 34–185), p<0.05. User‑rated needle control was significantly increased in the Epidrum group, p<0.05. There was no significant difference for success or failure of epidural anaesthesia between groups. One dural puncture occurred in the control group. No other significant differences existed between the 2 groups. |
|
Conclusions |
The Epidrum reduced the time required for identifying the epidural space. |
|
Abbreviations: ASA, American Society of Anaesthesiologists; IQR, interquartile range; LOR, loss of resistance; L, lumbar; SD, standard deviation; T, thoracic. |
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Table 3 Summary of the randomised controlled trials
|
The Epidrum |
Conventional LOR technique |
Analysis |
|
|
Kim et al. (2012) |
|||
|
Randomised |
n=54 |
n=54 |
|
|
Efficacy |
n=54 |
n=54 |
|
|
Primary outcome: Time required to identify the epidural space in seconds |
Mean 18.6±8.7 SD |
Mean 31.5±16.8 SD |
p<0.001 |
|
Selected secondary outcomes: |
|||
|
Failure to identify the epidural space |
0 |
5 |
p=0.022 |
|
More than 2 attempts |
2 |
13 |
p=0.002 |
|
Ease of epidural space identification score |
2 (2–4) |
3 (25) |
p<0.001 |
|
Operator satisfaction score |
2 (2–4) |
3 (2–5) |
p<0.001 |
|
Safety |
n=54 |
n=54 |
|
|
Patients reporting serious adverse events |
Not applicable |
Not applicable |
|
|
Dural puncture |
0 |
1 |
p=0.155 |
|
Sawada et al. (2012) |
|||
|
Randomised |
n=40 |
n=40 |
|
|
Efficacy |
n=40 |
n=40 |
|
|
Primary outcome: Time required to identify the epidural space |
Median 28 IQR 10‑76 |
Median 90 IQR 34‑185 |
p<0.05 |
|
Selected secondary outcomes: |
|||
|
Control of epidural needle (easy/moderate/difficult) |
40/0/0 |
27/7/6 |
p<0.05 |
|
Certainty of epidural space identification (certain/moderate/uncertain) |
40/0/0 |
33/0/7 |
p>0.05 |
|
Safety |
n=40 |
n=40 |
|
|
Patients reporting serious adverse events |
Not applicable |
Not applicable |
|
|
Dural puncture |
0 |
1 |
Not reported |
|
Abbreviations: CI, confidence interval; ITT, intention to treat; IQR, interquartile range; n, number of patients; RR, relative risk. |
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Recent and ongoing studies
Two ongoing clinical trials on the Epidrum for epidural anaesthesia were identified in the preparation of this briefing.
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NCT01597466: A randomised clinical trial based in France to evaluate the use of the Epidrum to identify the epidural space in patients requiring thoracic epidural analgesia. This is an ongoing study with July 2014 as the original estimated completion date.
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NCT01574391: A randomised clinical trial based in Ireland to evaluate whether the use of the Epidrum to identify the epidural space in women in labour reduces morbidity, when compared with standard LOR techniques. The recruiting status of this study is unknown and the original estimated completion date was July 2012.
Costs and resource consequences
No published evidence on resource consequences of the Epidrum was identified in the systematic review of evidence.
If the Epidrum is adopted in the NHS, it could help clinicians identify the epidural space more quickly in situations where epidural anaesthesia is needed, such as childbirth (including caesarean sections) and thoracic, abdominal, pelvic or lower limb surgery. It is estimated that about 335,000 epidural anaesthesia procedures (including combined spinal and epidurals) are performed in the UK annually (Cook et al. 2009).
No change to current service organisation or delivery would be needed in order for the Epidrum to be used. No other additional facilities or technologies are needed alongside the Epidrum device.
According to the manufacturer, the Epidrum is not being actively promoted in the UK and only a few clinicians currently have experience in using the device.
Strengths and limitations of the evidence
It was unclear in both studies what randomisation method was used to allocate patients to the treatment groups. In the study by Kim et al. (2012), patients were matched for age, gender, height and weight, and in the study by Sawada et al. (2012) they were additionally matched for the spinal level at which the epidural was inserted. However, it is unclear if other confounding factors were equally balanced across the groups. As a result, selection bias cannot be excluded.
Patient and investigator blinding (that is, not being aware of which treatments are being assigned) is especially important when the outcome measures are subjective, such as user satisfaction scores and the certainty of epidural space identification. In the 2 randomised controlled trials, the operators and independent observer collecting the results were not blinded to the use of the Epidrum compared with the standard LOR technique, increasing the possibility of performance bias. This limitation is not specific to these trials. Although blinding of the operator is standard practice for studies involving drugs, it is often not feasible in studies involving medical devices, because the operator can see which device is being used.
A sample size calculation was presented in only 1 of the studies (Kim et al. 2012). The sample size was calculated only for the primary outcome of 'time to identify the epidural space'. The studies were not powered to detect any differences in the secondary outcomes, including any safety issues such as the rate of adverse events (such as dural puncture).
Both studies had objective measurements for the primary outcomes. However, the secondary outcomes of 'operator satisfaction score' and 'ease of epidural space identification' were subjective and could be susceptible to bias. Finally, neither study used an objective measure of identifying the epidural space as a reference, nor did they consider patient‑related outcomes such as the level and duration of anaesthesia.
The results from the 2 randomised controlled trials suggest that the device is at least as easy to use as the conventional LOR technique. In addition, they showed that using the Epidrum decreased the time needed to accurately identify the epidural space compared with the conventional LOR technique. On average, the time needed was 13 to 60 seconds less in the Epidrum group, so although the results were statistically significant, their clinical significance is unclear.
The manufacturer states that the Epidrum could in future be used with smaller gauge epidural needles, which are associated with lower rates of post‑dural puncture headaches and haematoma formation. In the studies by Sawada et al. (2012) and Kim et al. (2012), a standard 18‑gauge needle was used. Finally, 2 studies sponsored by the manufacturer and published as abstracts in 2010 (Hasan et al. 2010; Roberts et al. 2010), as well as the study by McMorrow et al. (NCT01574391, with an estimated completion date of July 2012), have not yet been published in full. This raises the possibility of publication bias. In the preliminary analyses of their findings, the authors (Hasan et al. 2010; Roberts et al. 2010) showed that the use of the Epidrum significantly reduced the failure rates and the number of attempts needed to complete the procedure compared to a conventional LOR technique. Similar to the studies by Kim et al. and Sawada et al., these studies did not include the incidence of dural puncture as a primary outcome measure and were not powered to detect any differences in the incidence of dural puncture when using the Epidrum.