test bpm check fuzzy, MANUAL
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Buyers’ guide
Low cost non-invasive blood pressure
monitors
CEP 08035
September 2008
Contents
2
Introduction............................................................................................... 3
Technical considerations.......................................................................... 6
Operational considerations....................................................................... 8
Economic considerations ....................................................................... 10
Purchasing ............................................................................................. 11
Market review ......................................................................................... 12
Recommendations ............................................................................... 119
Acknowledgements .............................................................................. 128
Glossary ............................................................................................... 129
References ...........................................................................................130
Appendix 1: Supplier contact details .................................................... 134
Appendix 2: EU procurement procedure .............................................. 137
Appendix 3: Data collection pro-forma ................................................. 139
Author and report information............................................................... 143
CEP 08035: September 2008
Introduction
3
General
This report is intended to assist in the selection of low cost automated non-invasive blood
pressure (NIBP) monitors. A similar buyers’ guide for hospital grade NIBP monitors was
published in May 2008 (CEP 08018). Information is presented in a standardised format to
help purchasers prepare a short-list of devices. The 44 models in this issue represent the
majority of low cost devices designed for use on the upper arm that were on the UK market
during 2007 and 2008.
Several manufacturers offer a wide range of models. Where this is the case, we have chosen
a representative sample of models from those available.
Models are presented alphabetically by manufacturer. Abbreviations used in this report are
defined in the Glossary (page 129).
Scope
The report reviews low cost monitors selected (see Method, page 12) from the large number
of automated blood pressure monitors available in the UK. Their prices ranged from £8.50 to
£98.99.
All 44 of the devices were capable of making automated measurement of blood pressure
using the oscillometric measurement technique. This works on the principle that when an
inflated cuff partially occludes blood flow in the brachial artery, pulsatile changes in blood
volume during each heart beat induce small (typically < 3 mmHg) pulses in the cuff. Devices
measure the size of these pressure pulses while inflating or deflating the cuff (see box,
page 7).
Devices were available for use on the upper arm or wrist. We excluded wrist devices from
this study (see European Society of Hypertension guidelines, page 5).
Eight devices required the cuff to be inflated manually using a supplied bulb inflator. As well
as making straightforward measurements of blood pressure and pulse rate, some monitors
had additional features, such as memory for storing multiple previous readings, and
connectivity to external printers and/or PCs, with software available to download readings for
archiving.
National guidance
British Hypertension Society guidelines
In 2004 the British Hypertension Society (BHS) issued guidelines [1] for management of
hypertension. Those relating to blood pressure measurements are reproduced below:
Use a properly maintained, calibrated and validated device.
Measure sitting blood pressure routinely; standing blood pressure should be recorded at
the initial estimate in elderly and diabetic patients.
Remove tight clothing, support arm at heart level, ensure hand relaxed and avoid talking
during the measurement procedure.
CEP 08035: September 2008
Introduction
4
Use a cuff of appropriate size: the bladder should surround at least 80% of the upper
arm; using too large a cuff will result in an underestimation of blood pressure, while too
small a cuff will lead to overestimation.
When using the auscultatory method (see box, page 6) lower mercury column slowly
(2 mmHg/s); read blood pressure to the nearest 2 mmHg; measure diastolic as
disappearance of sounds (phase V).
Take the mean of at least two readings; more recordings are needed if marked
differences between initial measurements are found.
Do not treat on the basis of an isolated reading.
MHRA guidelines
In 2005 the Medicines and Healthcare Products Regulatory Agency (MHRA) issued a report
containing recommendations of the Independent Advisory Group on Blood Pressure
Monitoring in Clinical Practice [2] and followed it up with a medical device alert [3]. Those
recommendations which are relevant to the selection of NIBP monitors are reproduced
below:
Recommendation 3
Where oscillometric blood pressure measurement is used, it should
not
be assumed that
a CE marked blood pressure monitor is automatically suitable for use in the diagnosis of
hypertension.
Recommendation 4
In those clinical conditions where oscillometry is inappropriate (e.g. arrhythmias, pre-
eclampsia and certain vascular diseases) an alternative method of pressure
measurement (auscultation, arterial cannulation) should be used.
Recommendation 5
The MHRA, in collaboration with the Committee on Blood Pressure Monitoring in Clinical
Practice,
should define acceptable performance criteria against which automated non-
invasive blood pressure monitors should be evaluated. Evidence for compliance with
these criteria should be obtained from properly conducted clinical trials [4,5,6,7,8]. The
population characteristics for which the device has been evaluated should be specifically
included.
Recommendation 6
The NHS and other healthcare sectors should only purchase devices that meet the
performance criteria in the recommendation above.
Recommendation 7
Auscultation as a method of determining blood pressure should continue to be taught to
healthcare workers as appropriate. Calibrated non-mercury devices, which do not rely on
oscillometry, should be made available in all clinical areas. These should be used to
check oscillometric results and other non auscultatory alternative blood pressure
measurement determination on individual patients. These devices should also be used in
clinical conditions where alternative methods may be inappropriate e.g. arrhythmia,
pre-eclampsia or specific vascular disease.
CEP 08035: September 2008
Market review
15
Table 2
BHS grading criteria
—see O'Brien E,
et al
[5]
Absolute difference between standard and test device
5 mmHg
10 mmHg
15 mmHg
Grade
Cumulative percentage of readings
A
60%
85%
95%
B
50%
75%
90%
C
40%
65%
85%
D
Worse than C
Readings taken by the device under validation are compared with those independently taken
by two trained observers using the auscultatory technique. The observer’s measurements
are performed simultaneously; the device measurements are performed sequentially to the
observer measurements. There are 85 subjects; 255 measurements are taken in total.
Grades are derived from the percentage of device readings within 5, 10 and 15 mmHg of the
observers’ readings. To achieve a particular grade, all three percentages must be equal to or
greater than the tabulated values above.
For studies where a BHS grade was not quoted in either a peer reviewed paper or in an
unpublished report we used ANSI/AAMI SP10 data to derive an equivalent BHS grade.
Criteria for recommendation
Our general recommendations are based on three criteria which are important to consider
when purchasing a device:
Accuracy: Passed ANSI/AAMI SP10 and achieved a BHS grade A or B (or
equivalent) in a clinical validation study for both systolic and diastolic pressure.
Level of evidence, in order of preference:
o
Independent clinical validation study published in a peer reviewed journal.
o
Independent clinical validation study with an unpublished report.
o
In-house clinical validation study and report.
Measurement performance comprising:
o
Excellent measurement repeatability (within 1 mmHg) from 30 consecutive
measurements of 120/80 mmHg when tested using a repeatable [14] laboratory
NIBP simulator.
o
At least two successful measurements from five attempts at each pressure range
setting and pulse rate setting (settings are shown in the pro-forma reproduced in
Appendix 3).
CEP 08035: September 2008
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