Advice

Clinical and technical evidence

Clinical and technical evidence

A literature search was done for this briefing in accordance with the interim 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 mibs@nice.org.uk.

Published evidence

Seven studies are summarised in this briefing, including over 513 patients (1 study did not report the number of patients and so the exact total is not clear). All studies compared the Bair Hugger temperature monitoring system with either invasive core temperature monitoring or minimally invasive temperature monitoring. The level of agreement between the devices was high. The manufacturer has re-branded the device since these studies were published but there have been no changes to the technology itself (previously known as SpotOn).

Table 2 summarises the clinical evidence as well as its strengths and limitations.

Overall assessment of the evidence

The evidence base is developing, both in availability and scope. It is currently focused on measurement accuracy compared with other temperature monitors and not on changes in patient management or outcomes. Only 3 studies have been published in full; others are only available as abstracts which give limited details about the studies.

Studies assessing clinical outcomes would improve the evidence base. These outcomes could include rates of hypothermia, recovery from surgery and length of hospital stay.

Table 2 Summary of clinical evidence

Cullen (2016)

Study size, design and location

Audit study, prospective data collection from 2 theatres in the UK. 221 intraoperative temperature measurements.

Intervention and comparator(s)

SpotOn temperature monitoring system compared with bladder or pharyngeal core temperature measurement.

Key outcomes

Paired temperature bias (difference in temperature) was 0.1°C (95% limits of agreement ±0.73°C).

Strengths and limitations

Abstract only, minimal data given, no details of the patients or surgery type. Temperature values taken at 4 time points only. Funding source not reported.

Maniken et al. (2016)

Study size, design and location

30 patients

Prospective cohort study

Finland

Intervention and comparator(s)

SpotOn temperature monitoring system Model 370 (all patients).

Mon-a-therm Foley with temperature sensor 400 series, urinary bladder (all patients).

Mon-a-therm general purpose temperature probe 400 series inserted into lower oesophagus (during vascular surgery, n=15) or nasopharynx and pulmonary artery (during cardiac surgery, n=15).

Swan-Ganz pulmonary artery temperature probe (cardiac surgery, n=15).

Key outcomes

Agreement was good between SpotOn and oesophageal temperature during vascular surgery, between SpotOn and pulmonary artery temperature during cardiac surgery (off cardiopulmonary bypass), and between SpotOn and nasopharyngeal temperature during cardiac surgery (on and off cardiopulmonary bypass).

Agreement in 1 patient during induced hypothermia below 32°C was poor.

Strengths and limitations

The study used automated, continuous temperature monitoring and included patients having 2 different types of surgery. However, the sample sizes in the 2 groups were small. Author has links with manufacturer, device supplied by manufacturer.

Jack et al. (2016)

Study size, design and location

29 patients

Prospective cohort study

UK

Intervention and comparator(s)

SpotOn

Oesophageal temperature probe

Key outcomes

Good level of agreement (difference between devices was 0.024 °C).

Strengths and limitations

Temperature values taken every minute. Small study, published as abstract only, minimal data given, no details of patients. Funding source not reported.

Arunachalam et al (2015)

Study size, design and location

166 patients

Prospective cohort study

UK

Intervention and comparator(s)

SpotOn thermometer

Tympanic membrane thermometer, no further details provided; assume this is surface temperature.

Key outcomes

Good concordance between temperatures taken by the SpotOn thermometer and tympanic membrane thermometer.

Strengths and limitations

Large prospective study but published as an abstract only. Few details of patients or when temperatures were recorded. Part of a bigger study of perioperative practice. Comparator was not measuring core temperature although the authors state this is their standard practice. Manufacturer helped in data collection, analysis and provided SpotOn recording devices.

Iden et al. (2016)

Study size, design and location

83 patients

Prospective cohort study

Germany

Intervention and comparator(s)

SpotOn

Nasopharyngeal probe

Sublingual probe

Key outcomes

Bias was 0.1°C or less compared with the nasopharyngeal probe and −0.37°C or less compared with the sublingual probe.

Strengths and limitations

Large, powered, prospective study including patients having 2 types of surgery. Temperature was taken at 3 time points only. 3.3% of patients were excluded because of SpotOn failure and 16% because of sublingual probe calibration failure. A further 12% were excluded from the analysis. Funded by the manufacturer.

Eshraghi (2014)

Study size, design and location

105 patients

Prospective cohort study

US

Intervention and comparator(s)

SpotOn prototype

Pulmonary artery catheter

Key outcomes

The overall mean difference (bias) was –0.23°C. Differences of 0.5 °C or less were seen between SpotOn and pulmonary artery catheter temperatures in 78% to 84% of measurements.

Strengths and limitations

Large prospective study using continuous temperature monitoring. 2 patients were excluded because of sensor failure. Data from a further 6 patients were excluded because of temperatures indicating sensor or software problems. Relevance of comparator to UK practice is unclear. Funded by the manufacturer.

Searle et al. (2014)

Study size, design and location

100 patients

Prospective cohort study

UK

Intervention and comparator(s)

SpotOn

Infra-red tympanic thermometer, no further details, assume surface temperature.

Key outcomes

Both methods showed similar averages. SpotOn had lower variability suggesting less random error.

Overall, 25% of patients were preoperatively labelled 'normothermic' by tympanic measures, when hypothermic according to SpotOn.

In recovery, SpotOn showed earlier recognition of normothermia.

Strengths and limitations

Large prospective study but published as an abstract only, minimal data given, no details of the patients. Temperature values taken half hourly. Comparator was not measuring core temperature. Funding source not reported.

Recent and ongoing studies