Clinical and technical evidence

A literature search was carried out for this briefing in accordance with the published process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting

Published evidence

Two publications (table 1) are summarised in this briefing. The first publication (Mariyaselvam et al. 2015a) reported the following evidence:

  • a clinical audit of bacterial contamination of standard 3‑way taps in a single intensive care unit in the UK

  • a manikin simulation study using standard 3‑way tap ports to determine the likelihood of accidental arterial injection by 'time-pressured' junior doctors in an intensive care unit in the UK

  • a laboratory study to determine the protection offered by the needle-free arterial non-injectable connector (NIC) against transmission of bacteria.

Evidence from the clinical audit and manikin study was not included in this briefing, because it does not provide direct evidence on the NIC.

The second publication (Mariyaselvam et al. 2015b) reported the following evidence:

  • Results of a national survey sent to every acute NHS trust in the UK (where the NIC was not in use) to gather information on the incidence of accidental administration into an arterial line in the past 5 years.

  • A regional survey carried out across 11 trusts in the east of England to gather information on the acceptability of the NIC to 258 users (including nurses, doctors, operating department practitioners and other healthcare staff) after a 6‑month implementation study. Further details of the respondents were not reported.

  • A cost-effectiveness assessment of the NIC which was also based on information gathered from the 6‑month implementation study of the NIC in 11 trusts in the east of England.

Findings from the national survey on accidental administration into an arterial line were not included in this briefing because it does not provide evidence in relation to the NIC.

Table 1 summarises the included evidence as well as its strengths and limitations.

Table 1: Summary of clinical evidence


Details of intervention and comparator


Strengths and limitations

Mariyaselvam, Heij, Laba et al. (2015a)

UK-based laboratory simulation study to determine the protection offered by the NIC against transmission of bacteria.

An artificial system was prepared to imitate arterial blood sampling and the flushing sequence through a 3‑way arterial connector.

A syringe that was intentionally heavily contaminated with bacteria was connected to a standard 3‑way arterial connector (n=20) or to the NIC (n=20).

Downstream flush samples and swabs of the 3‑way tap ports were collected.

Bacterial growth was found in 85% and 100% of samples and swabs respectively, when using standard 3‑way arterial connectors.

No bacterial growth was found in any samples or swabs when the NIC was used.

The researchers used a syringe that was more heavily contaminated than would be expected in normal clinical practice, and showed that even when bacterial contamination is excessively high, it is not transmitted to the port or the arterial blood sample. This was done in an artificial system designed to imitate arterial blood sampling and flushing in real-life, because it would be unethical to do such a test in patients. However, transmission rates using standard connectors may be much lower in clinical practice than when used with a heavily contaminated syringe and it is not known whether there would be a clinically or statistically significant difference in a real-world situation.

Outcome assessors were not blinded to the type of connector, and 2 of the investigators have a profit share arrangement for the device.

Mariyaselvam, Blunt, Young (2015b) Implementation study carried out in 11 NHS trusts in the east of England that had been using the NIC for 6 months.

Cost-effectiveness assessment, comparing the NIC with a standard arterial connector, based on: estimates of staff time; process steps and consumables; costs of erroneous injections; and costs of bloodstream infections.

Use of the NIC could lead to better outcomes at lower costs, saving £285 per year for an average trust.

Cost-effectiveness estimates were derived from real-world use of the NIC in NHS settings.

Uncertainties around the parameters and assumptions used were not explored. Insufficient details about the methods of the analysis were reported to allow judgement of whether the cost savings are likely to be realised elsewhere. The study has not yet been peer-reviewed as part of a publication process.

Survey of 258 staff who had used the NIC, comparing the NIC with a standard arterial connector.

Acceptability for users:

  • 96.5% said the NIC made it easier to identify the arterial line, although 70.9% thought that the standard connector was adequate for identifying an arterial line

  • 81% wanted to continue using NIC after the study ended

  • 22% noted problems with using the NIC.

The survey was based on real-world use of the NIC in NHS settings.

Insufficient details were reported to determine if the survey used was valid. One of the investigators on implementation study has a profit share arrangement for the device. The study has not yet been peer-reviewed as part of a publication process.

Abbreviation: NIC, needle-free arterial non-injectable connector.

Strengths and limitations of the evidence

The evidence to support the NIC is from laboratory studies and user experience surveys. Any clinical study designed to show that the NIC prevents accidental injection into or blood loss from arterial lines would need to be very large, in order to be adequately powered to show a reduction in the incidence of these rare events. The evidence for prevention of bacterial contamination is limited to a small laboratory study and the benefit of the NIC in a clinical situation is unknown. The NIC was compared with 1 type of connector, so the benefit compared with the various types of connectors currently used in the NHS is also unclear.

The evidence on acceptability to users in this MIB is from a representative group of NHS staff, and indicates that most users would choose to continue using the NIC. The NIC offers a safety feature not found in currently used arterial connectors that could also lead to cost savings. However, there is uncertainty about whether the estimated cost savings are accurate, and so these could be greater or less than estimated if it is adopted more widely in the NHS.

Recent and ongoing studies

No ongoing or in-development trials on the NIC were identified.