Download Mercury versus Non-Mercury Sphygmomanometers: A

TITLE:
Mercury versus Non-Mercury Sphygmomanometers: A Review of the
Comparative Clinical Effectiveness and Guidelines
DATE:
25 September 2012
CONTEXT AND POLICY ISSUES
A mercury manual sphygmomanometer is a device attached to the forearm to record arterial
pulsations. Basic components include an inflatable cuff to put pressure on the artery, a
pressure-measuring scale, and a bulb to inflate the cuff. As the cuff is inflated, the mercury in
the manometer rises through the column, and the pressure is displayed on the scale. A
stethoscope is placed over the brachial artery of the elbow to detect the systolic and diastolic
pressure during the slow deflation of the pressure of the cuff. Since the instrument relies on the
human judgment to detect systolic and diastolic pressure, it is termed an auscultatory device.1
Accuracy of mercury sphygmomanometers depend on proper validation, calibration, and
maintenance. Several factors may affect the accuracy including measurement technique, proper
cuff size, proper placement of the cuff, accurate recording of the systolic and diastolic
endpoints, patient’s level of anxiety, and patient-physician interaction (e.g. “white coat
response”).1 Poor maintenance of the mercury sphygmomanometer may result in loss of
accuracy due to equipment deterioration such as an obscure mercury column due to dirt or
mercury oxidation, faded scales that are hindering the readings of mercury meniscus, and
mercury leak, which is a major health concern.2 Despite its limitations, the mercury
sphygmomanometer is still considered “gold standard” in terms of accuracy.3
There are two common types of non-mercury sphygmomanometers: aneroid and oscillometric
devices.1 The aneroid devices are also operated manually and require a normal blood pressure
cuff and a stethoscope, but are liquid-free and use mechanical parts to relay the blood pressure
to the gauge.1 The oscillometric devices are operated automatically, and the inflation and
deflation of the cuff are controlled electronically.1 Based on the pressure-wave changes, an
algorithm in the oscillating device is used to calculate the systolic and diastolic pressures, which
are displayed on a digital readout.1 Accuracy of mercury-free sphygmomanometers also
depends on proper maintenance, calibration and validation.4 The perceive benefits of
oscillometric devices are that they are more accurate, less time consuming, easier to operate,
and safer in terms of being mercury-free.5,6 Oscillometric devices may result in greater “withinsubject” reliability than manual readings, by eliminating digit preference (the preference to round
a value to a lower or higher one), observer bias and the white coat effect.6 However, the
Disclaimer: The Rapid Response Service is an information service for those involved in planning and providing health care in Canada. Rapid
responses are based on a limited literature search and are not comprehensive, systematic reviews. The intent is to provide a list of sources and
a summary of the best evidence on the topic that CADTH could identify using all reasonable efforts within the time allowed. Rapid responses
should be considered along with other types of information and health care considerations. The information included in this response is not
intended to replace professional medical advice, nor should it be construed as a recommendation for or against the use of a particular health
technology. Readers are also cautioned that a lack of good quality evidence does not necessarily mean a lack of effectiveness particularly in
the case of new and emerging health technologies, for which little information can be found, but which may in future prove to be effective. While
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accuracy of oscillometric devices remains questionable and the use of oscillometric devices is
not clinically appropriate when patient has an arrhythmia.7
The aim of this report is to review the comparative accuracy, safety and guidelines regarding the
use of mercury versus non-mercury sphygmomanometers for the measurement of blood
pressure.
RESEARCH QUESTIONS
1.
What is the evidence regarding the comparative accuracy of mercury versus nonmercury sphygmomanometers for the measurement of blood pressure?
2.
What are the evidence-based guidelines regarding the use of mercury versus nonmercury sphygmomanometers in higher risk patient groups such as pregnancy and
pediatric specialty clinics?
KEY MESSAGE
Automated (oscillometric) office blood pressure devices, with proper maintenance, calibration
and validation, can be used as a replacement for the mercury sphygmomanometer in office
settings for the measurement of blood pressure. In pregnant women, children, patients with
arrhythmia, and hypertensive or hypotensive patients, identified guidelines recommend that the
measurement readings of automated devices should be validated with a mercury
sphygmomanometer. There is no evidence on the comparison of aneroid devices with mercury
sphygmomanometer.
METHODS
Literature Search Strategy
A limited literature search was conducted on key resources including PubMed, The Cochrane
Library (2012 Issue 8), Canadian and major international health technology agencies, as well as
a focused Internet search. Methodological filters were applied to limit retrieval to health
technology assessments, systematic reviews, meta-analyses, randomized controlled trials, nonrandomized studies containing safety data, and guidelines. The search was also limited to
English language documents published between August 27, 2007 and August 27, 2012.
Selection Criteria and Methods
One reviewer screened the titles and abstracts of the retrieved publications and evaluated the
full-text publications for the final article selection, according to selection criteria presented in
Table 1.
Table 1: Selection Criteria
Population
Q1: Adult and pediatric patients in hospital or medical clinic
Q2: High risk patients
Intervention
Non-mercury sphygmomanometers
Comparator
Mercury sphygmomanometers (gold standard)
Mercury versus Non-Mercury Sphygmomanometers
2
Outcomes
Study Designs
Accuracy and calibration needs for non-mercury
sphygmomanometers
Possible harms (acute inhalation or chronic exposure) due to mercury
spill with mercury sphygmomanometers
Guidelines regarding the use of non-mercury sphygmomanometers
Health technology assessments, systematic reviews, meta-analyses,
randomized controlled trials, non-randomized controlled trials (for
safety only), guidelines
Exclusion Criteria
Studies were excluded if they did not satisfy the selection criteria in Table 1, if they were
published prior to 2007, duplicate publications of the same study, or included in a selected
health technology assessment or systematic review.
Critical Appraisal of Individual Studies
The methodological quality of the systematic reviews were assessed using AMSTAR checklist.8
The quality of the RCTs and observational studies was assessed using Downs and Black
checklist.9 The Appraisal of Guidelines Research & Evaluation (AGREE) instrument10 was used
to evaluate the quality of the included guidelines.
For the critical appraisal of studies, a numeric score was not calculated. Instead, the strength
and limitations of the study were described.
SUMMARY OF EVIDENCE
Quantity of Research Available
The literature search yielded 55 citations. Upon screening titles and abstracts, eight potential
relevant articles were retrieved for full-text review. Ten additional relevant reports were retrieved
from other sources. Of the 18 potentially relevant articles, nine were included in this review.
They are two systematic reviews,11,12 three RCTs,13-15 and four guidelines.16-19 The study
selection process is outlined in a PRISMA flowchart (Appendix 1).
Summary of Study Characteristics
A summary of study characteristics can be found in Appendix 2.
Systematic reviews and meta-analyses:
The systematic review and meta-analysis by Stergiou et al. 201211 assessed the accuracy of
automated blood pressure measurement in patients with sustained atrial fibrillation. Eight
observational studies (12 validations: four ambulatory, five home, and three office devices)
published between January 1986 and October 2011 with a total of 566 participants (57% men,
mean age 73 years) with sustained atrial fibrillation were included. Sample sizes ranged from 20
to 255 participants. A standard mercury sphygmomanometer was used as reference method in
five validations, a Hawksley random-zero method in five, and an aneroid sphygmomanometer in
two. For comparison of the two methods, blood pressure was measured either sequential (nine
validations) or simultaneous (three validations). Average values pooled by random-effects meta-
Mercury versus Non-Mercury Sphygmomanometers
3
analysis and accounting for heterogeneity were estimated with 95% confidence intervals for
correlation coefficients and for differences between automated and auscultatory blood pressure
measurements (systolic and diastolic).
The systematic review by Skirton et al. 201112 compared the accuracy and appropriateness of
auscultatory (manual) and oscillometric (automated) devices for measuring blood pressure in
clinical settings. Sixteen studies (15 observational studies and 1 RCT) published in English
between January 1997 and May 2009 were included. Quality of the evidence was appraised
and the results were summarized in a narrative form. The score for quality appraisal ranged
from 45 to 95%, covering study design, subject group, means of analysis, sample size and
estimates of variance. In nine of the studies, the manual reading was done by “trained
observers”, while in three studies the readings were made by clinical nurses. In other studies,
measurements were taken by nurses with or without specific training or by medical residents.
The practice settings for the studies included emergency care, hypertension clinics, general
wards, or outpatient clinics. Sample sizes ranged from 33 to 997 participants. The way
measurements were taken and recorded varied among studies.
Randomized controlled trials:
The trial by Brown et al. 201213 was a prospective randomized open study with blinded
endpoints design. The objective was to determine whether women diagnosed with hypertension
in pregnancy, using traditional mercury sphygmomanometers, have equivalent pregnancy
outcomes when blood pressure is measured thereafter by either an automated blood pressure
recorder or a mercury sphygmomanometer throughout pregnancy. Pregnant women with
hypertension (mean age 31 years, N=220) were randomized into one of the two groups: the
mercury sphygmomanometer (n=110) or the automated (Omron HEM-705CP) blood pressure
recording group. The primary outcome was the number of women in each group developing any
episode of severe hypertension (≥170 mm Hg systolic and/or ≥110 mm Hg diastolic), which was
used as a surrogate marker for detecting the risk of stroke and alerting the cases of severe
preeclampsia or gestational hypertension. Secondary endpoints included gestational time at
birth, small for gestational age (<10th centile) rates, caesarean section, and induction of labor
rates.
The multi-site cluster randomized controlled trial by Myers et al. 201114 compared the quality
and accuracy of manual office blood pressure and automated blood pressure using the awake
ambulatory blood pressure as a gold standard. The setting was primary care practices in five
cities in eastern Canada. The sites consisted of either one family physician or a group of two or
three physicians sharing the same office space. Adult patients (over 45 years, N=555) with
systolic hypertension (160 mm Hg / 95 mm Hg for untreated or 140 mm Hg / 90 mm Hg for
treated) and no serious comorbidities were randomly assigned to either manual office blood
pressure with continuing use of manual sphygmomanometer (control group) or automated office
blood pressure (intervention group) using the BpTRU device. The baseline characteristics were
balanced between groups in terms of age, gender, duration of hypertension, antihypertensive
treatment and cigarette smokers. The BpTRU is a fully automated sphygmomanometer that
records blood pressure by an oscillometric method. It was set to take readings at two minute
intervals (from the start of one reading to the start of the next one) while the patients were left
alone during five readings. For the manual office blood pressure control group, physicians
continued recording blood pressure as before, without any additional instructions on proper
blood pressure measurement technique. All patients were instructed to have 24 hour
ambulatory blood pressure monitoring using a Spacelabs Model 90207 unit, which has been
validated for accuracy. The device was set to record blood pressure at 15 minute intervals
between 6:00 and 22:00 and at 30 minute intervals during the night. The primary outcome was
Mercury versus Non-Mercury Sphygmomanometers
4
the mean estimated difference between the mean awake ambulatory blood pressure and the
automated blood pressure (intervention group) or manual office blood pressure (control group)
at the first office visit after enrolment.
Lamarre-Cliché et al. 201115 conducted a randomized, crossover study to compare the blood
pressure measurement by mercury sphygmomanometer and other three blood pressure
measurement modalities, namely the automated office blood pressure (AOBP) device (BpTRU),
the ambulatory blood pressure measurement (ABPM) device (Spacelabs, model 90207-30), and
self-measurement (Omron HEM-780CAN). Patients (mean age 58 years, N=101) from
hypertension clinic with average blood pressure of 134 ± 12.7/83.6 ± 8.8 mm Hg were recruited
and randomized to either the office or home group. The office group was then randomized to
undergo an AOBP – Sphygmomanometer or Sphygmomanometer – AOBP sequence. The
home group was randomized to undergo either a self-measurement – ABPM or ABPM – self
measurement sequence. The total length of the study was 8 to 14 days. The primary study
outcome was achievement of blood pressure goal.
Guidelines:
The characteristics on the grading of recommendations and levels of evidence used to develop
the corresponding guidelines are summarized in Appendix 3.
Summary of Critical Appraisal
The strengths and limitations of included studies are summarized in Appendix 4.
The methodological quality assessment of the systematic review by Stergiou et al. 201211 met 9
out of 11 items, while that of the systematic review by Skirton et al. 201112 met 8 out of 11 items
of the AMSTAR criteria. In Stergiou, the scientific quality of the include studies was not
assessed and considered in the conclusions. In Skirton, the likelihood of publication bias was
not assessed, methods of study selection and data extraction were not described, and there
was no pooling of the results from the included studies.
Overall, all three included RCTs13-15 met most items of the Downs and Black checklist for
measuring study quality. A major limitation of all RCTs was the lack of identification of potential
confounders. One RCT13 made attempt to blind the observers undertaking data collection and
analyzing data.
Although the scope and purpose were explicit, the included guidelines16-19 suffered from multiple
limitations, covering stakeholder involvement, rigour of development applicability, and editorial
independence according to AGREE instrument. Methods used to search for the evidence were
not reported in the identified guidelines. One guideline16 reported procedures for updating the
recommendations. Clarity and presentation criteria were met in three guidelines.16,17,19
Summary of Findings
The main study findings and authors’ conclusions from the clinical studies can be found in
Appendix 5.
Systematic review:
In the systematic review and meta-analysis by Stergiou et al.,11 automated measurements were
higher than manual blood pressure measurements [pooled average systolic difference 0.5 mm
Hg, 95% CI -0.9, 1.9; diastolic 2.5 mm Hg, 95% CI -0.6, 5.7). Pooled correlation coefficients
between automated and manual bleed pressure measurements were stronger for systolic than
Mercury versus Non-Mercury Sphygmomanometers
5
diastolic blood pressure (r=0.89 versus 0.76, P<0.001). Four of eight studies reporting data
regarding the within 5 mm Hg ESH-IP criterion have passed for SBP (at least 65% of
comparisons within 5 mm Hg) and two for DBP, suggesting better measurement accuracy for
systolic blood pressure. Three studies showed no impact of heart rate on the blood pressure
differences between automated and manual measurements. It was concluded that automated
blood pressure monitors are accurate in measuring systolic but not diastolic blood pressure in
elderly with atrial fibrillation.
In the systematic review by Skirton et al 2011,12 oscillometric (automated) devices were found
less accurate than the mercury sphygmomanometer in 10 of the included studies. However, in
most case the authors of the included studies concluded that the differences were not clinically
significant, and the oscillometric devices could be used in the clinical settings, with the
exceptions being used with hypertensive patients, patients with arrhythmia and patients with
trauma.
Randomized controlled trial:
In the trial by Brown et al. 2012,13 blood pressures obtained by six sequential recordings
(alternating between mercury and automated) at randomization, according to the allocated
group were similar. Both groups had similar maternal and fetal outcomes. The percentage of
women with any episode of severe hypertension was similar between groups (39% for mercury
vs. 44% for automated, P=0.5). The average number of episodes of severe hypertension per
woman affected was also similar between groups (3 ± 2 for mercury vs. 4 ± 5 for automated,
P=0.3). Small gestational age (<10th centile) occurred more frequently in those using automated
blood pressure than mercury sphygmomanometer (17% vs. 12%), but the difference was not
statistically significant (P=0.3). Birth weight and perinatal mortality were similar among groups. It
was concluded that the use of automated blood pressure recording is associated with similar
maternal and fetal outcomes compared with mercury sphygmomanometer.
In the trial by Myers et al. 2011,14 both groups showed a drop in mean office blood pressure
between the pre-study office visit and blood pressure recorded after enrolment. The reduction in
the automated group was numerically higher than that in the manual group, but the difference
was not statistically significant. With respect to the primary outcome measure, the mean
estimated difference between awake ambulatory blood pressure and office blood pressure after
enrolment was -2.3 (95% confidence interval [CI] -0.3 to -4.3) / -3.3 (95% CI -2.2 to -4.4)
(P=0.02 / P<0.001) for automated group and -6.5 (95% CI -4.3 to -8.6) / -4.3 (95% CI -2.9 to 5.8) (P<0.001 / P<0.001). The difference for systolic manual office blood pressure (-6.5) was
significantly greater (P=0.006) than that for the systolic automated office blood pressure (-2.3).
Automated office blood pressure showed a stronger (P<0.001) within group correlation (r=0.34 /
r=0.56) with the awake ambulatory blood pressure compared with manual office blood pressure.
The number of individual readings that showed digit preference, with readings being rounded off
to the nearest zero, was significantly reduced (P<0.001) when automated office blood pressure
readings were taken. It was concluded that the quality and accuracy of the automated blood
pressure was better than the manual office blood pressure in relation to the awake ambulatory
blood pressure. The automated office blood pressure measurement significantly reduced the
white coat response compared with the manual office blood pressure measurement.
In the trial by Lamarre-Cliché et al. 2011,15 average blood pressures taken from all
measurement methods were similar with the exception of daytime ambulatory blood pressure
measurement (ABPM), which resulted in significantly greater systolic pressure compared with
other methods. With the sphygmomanometer, blood pressure decreased by 1.2 ± 5.5 (P=0.029)
/ 0.4 ± 4.3 (P=0.40) mm Hg between the first and third measurements. With the automated
Mercury versus Non-Mercury Sphygmomanometers
6
office blood pressure (AOBP) device, blood pressure decreased by 2.8 ± 7.5 (P=0.0004) / 1.1 ±
4.7 (P=0.40) mm Hg between the first and fifth measurements. According to cut-off values,
target blood pressure of 140/90 mm Hg was reached in 67% of patients according to office
sphygmomanometer and 70% according to the AOBP. Kappa coefficients measuring
concordance showed fair agreement between two office methods (AOBP and
sphygmomanometer; kappa coefficient 0.653; 95% CI 0.493 to 0.813). AOBP had the best
diagnostic performance when using a sphygmomanometer as the gold standard but had
variable results when choosing other standards. It was concluded that AOBP device can be
used as a replacement for the sphygmomanometer in office settings for the measurement of
blood pressure in hypertensive patients.
Guidelines:
Three guidelines were identified that provided recommendations on the use of blood pressure
measuring devices in hypertensive adults, in children, and in pregnant women.
Recommendations stated that extra care should be given to the use of automated device in
measuring blood pressure for patients having pulse irregularity, because the device may not
measure blood pressure accurately. In pregnant women, mercury sphygmomanometer remains
the gold standard for measurement of blood pressure. Automated or aneroid devices can be
used to monitor blood pressure in women with preeclampsia. Because automated and aneroid
devices are prone to error, it is recommended that a mercury sphygmomanometer should be in
place for validation. In children, mercury or aneroid sphygmomanometer is recommended to be
used for diagnostic evaluation of blood pressure elevation. However, automated devices may be
acceptable for routine surveillance or in newborns and young infants, in whom auscultation may
be difficult.
Limitations
Clinical
Several limitations of the two systematic reviews11,12 included differences in patient populations
among studies, differences in protocol design, the lack of information about sample selection,
and small sample sizes in some included studies. Many included studies in the systematic
reviews were of observational design, which suffered from potential biases in selection and
measurement.
Due to the nature of the studies, it is difficult to conduct a blinded RCT in blood pressure
measurement. All three RCTs used open-labeled design. However, one RCT13 reported an
attempt to blind those measuring the outcomes. The use of one type of automated device
(BpTRU in two trials14,15 and Omron in one trial13) in each trial makes it difficult to extrapolate the
findings to other automated devices. The study population in each trial was selective and it is
not known for certain if the findings could be applied to the general population.
Guidelines
Of the four identified guidelines, one was from Canada,19 which had recommendations for the
type of device for blood pressure measurement in pregnant women. There was no specific
guideline emphasizing the use of blood pressure monitoring devices, rather recommendations
on the measurement of blood pressure were part of the management guidelines of specific
individuals with hypertension. There were no tools or algorithms for the use of different type of
devices in each situation.
Mercury versus Non-Mercury Sphygmomanometers
7
CONCLUSIONS AND IMPLICATIONS FOR DECISION OR POLICY MAKING
The collective current evidence suggests that automated office blood pressure monitoring
devices, which are mercury-free, can be used in substitution of the mercury
sphygmomanometer in clinical settings, although there are still some concerns about the
accuracy of the devices with respect to specific populations such as those with hypertension,
hypotension, arrhythmia, and children. Evidence from one RCT suggests that the maternal and
fetal outcomes were comparable between automated and manual devices used to monitor
throughout pregnancy. The mercury sphygmomanometer is still considered as the “gold
standard” according to clinical practice guidelines for blood pressure measurement in patients
with pulse irregularity, in children, and in pregnant women with hypertension. In those patients, it
was recommended that blood pressure readings by automated devices should be verified by a
mercury sphygmomanometer or an aneroid device. No evidence on the comparison of aneroid
devices with mercury sphygmomanometers was identified.
PREPARED BY:
Canadian Agency for Drugs and Technologies in Health
Tel: 1-866-898-8439
www.cadth.ca
Mercury versus Non-Mercury Sphygmomanometers
8
REFERENCES
1.
World Health Organization. Replacement of mercury thermometers and
sphygmomanometers in health care. Technical guidance [Internet]. Geneva: WHO; 2011.
[cited 2012 Sep 14]. Available from:
http://whqlibdoc.who.int/publications/2011/9789241548182_eng.pdf
2.
Markandu ND, Whitcher F, Arnold A, Carney C. The mercury sphygmomanometer should
be abandoned before it is proscribed. J Hum Hypertens. 2000 Jan;14(1):31-6.
3.
Buchanan S, Orris P, Karliner J. Alternatives to the mercury sphygmomanometer. J Public
Health Policy. 2011 Feb;32(1):107-20.
4.
Scientific Committee on Emerging and Newly Identified Health Risks. Mercury
sphygmomanometers in healthcare and the feasibility of alternatives [Internet]. Brussels:
European Commission; 2009. [cited 2012 Sep 14]. Available from:
http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_025.pdf
5.
Medicines and Healthcare products Regulatory Agency. Minutes of the meeting of the
Committee on Blood Pressure Monitoring in Clinical Practice, Tuesday, 4 November 2003.
London (UK): The Agency; 2003.
6.
Myers MG, Godwin M. Automated office blood pressure. Can J Cardiol. 2012
May;28(3):341-6.
7.
Beevers G, Lip GY, O'Brien E. ABC of hypertension. Blood pressure measurement. Part Isphygmomanometry: factors common to all techniques. BMJ [Internet]. 2001 Apr 21 [cited
2012 Sep 14];322(7292):981-5. Available from:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1120141
8.
Shea BJ, Grimshaw JM, Wells GA, Boers M, Andersson N, Hamel C, et al. Development
of AMSTAR: a measurement tool to assess the methodological quality of systematic
reviews. BMC Med Res Methodol [Internet]. 2007 Feb 15 [cited 2012 Aug 8];7:10.
Available from: http://www.biomedcentral.com/1471-2288/7/10
9.
Downs SH, Black N. The feasibility of creating a checklist for the assessment of the
methodological quality both of randomised and non-randomised studies of health care
interventions. J Epidemiol Community Health [Internet]. 1998 Jun [cited 2012 Aug
8];52(6):377-84. Available from:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1756728/pdf/v052p00377.pdf
10.
The AGREE Collaboration. Appraisal of guidelines for research and evaluation (AGREE)
instrument [Internet]. London: The AGREE Research Trust; 2001 Sep. [cited 2012 Aug 8].
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11.
Stergiou GS, Kollias A, Destounis A, Tzamouranis D. Automated blood pressure
measurement in atrial fibrillation: a systematic review and meta-analysis. J Hypertens.
2012 Aug 21. Epub ahead of print.
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12.
Skirton H, Chamberlain W, Lawson C, Ryan H, Young E. A systematic review of variability
and reliability of manual and automated blood pressure readings. J Clin Nurs. 2011
Mar;20(5-6):602-14.
13.
Brown MA, Roberts LM, Mackenzie C, Mangos G, Davis GK. A prospective randomized
study of automated versus mercury blood pressure recordings in hypertensive pregnancy
(PRAM Study). Hypertens Pregnancy. 2012;31(1):107-19.
14.
Myers MG, Godwin M, Dawes M, Kiss A, Tobe SW, Grant FC, et al. Conventional versus
automated measurement of blood pressure in primary care patients with systolic
hypertension: randomised parallel design controlled trial. BMJ [Internet]. 2011 [cited 2012
Sep 4];342:d286. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3034423
15.
Lamarre-Cliche M, Cheong NN, Larochelle P. Comparative assessment of four blood
pressure measurement methods in hypertensives. Can J Cardiol. 2011 Jul;27(4):455-60.
16.
National Institute for Health and Clinical Excellence. Hypertension: clinical management of
primary hypertension in adults [Internet]. London: NICE; 2011 Aug. 36 p. [cited 2012 Sep
4]. (Clinical Guidelines CG127). Available from:
http://guidance.nice.org.uk/CG127/NICEGuidance/pdf/English
17.
Cincinnati Children's Hospital Medical Center. Blood pressure measurement in children
[Internet]. Cincinnati (OH): The Centre; 2009 Jan 9. 9 p. [cited 2012 Sep 4]. (Best
evidence statement (BESt)). Available from:
http://www.cincinnatichildrens.org/assets/0/78/1067/2709/2777/2793/9198/20912557-f3e949b6-9f30-0f66bb9c8efb.pdf
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Lowe SA, Brown MA, Dekker G, Gatt S, McLintock C, McMahon L, et al. Guidelines for the
management of hypertensive disorders of pregnancy 2008 [Internet]. Sydney: Society of
Obstetric Medicine of Australia and New Zealand (SOMANZ); 2008. 31 p. [cited 2012 Sep
4]. Available from: http://www.somanz.org/pdfs/somanz_guidelines_2008.pdf
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Magee LA, Helewa M, Moutquin JM, von DP, Hypertension Guideline Committee,
Strategic Training Initiative in Research in the Reproductive Health Sciences (STIRRHS)
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Mercury versus Non-Mercury Sphygmomanometers
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APPENDIX 1: Selection of Included Studies
55 citations identified from electronic
literature search and screened
47 citations excluded
8 potentially relevant articles
retrieved for scrutiny (full text, if
available)
10 potentially relevant
reports retrieved from
other sources (grey
literature, hand
search)
18 potentially relevant reports
9 reports excluded:
irrelevant comparator (3)
published in language other than
English (1)
observational study with no safety
data (1)
other (review articles, editorials)(4)
9 reports included in review
2 SR/MA
3 RCTs
4 guidelines
Mercury versus Non-Mercury Sphygmomanometers
11
APPENDIX 2: Characteristics of Included Clinical Studies
First
Author,
Publication
Year,
Country
Study
Design
Patient
Intervention
characteristics,
sample Size (n)
Systematic reviews and meta-analyses
Stergiou et al.
Systematic
Individuals (57%
11
2012
review and
men, mean age 73
meta-analysis years) with
Greece
sustained atrial
fibrillation from 8
studies, N=566
Skirton et al.
Systematic
Participants
12
2011
review
(inpatients and
outpatients) with or
UK
without elevated
blood pressure from
16 included studies
(15 observational
studies and 1 RCT),
N=4,429
Randomized controlled trials
Brown et al.
RCT open
Women (mean age
13
2012
study with
31 years) with
blinded end
hypertension in
Australia
points
pregnancy
(outpatients and
Source of
Follow-up:
inpatients), N=220
funding: not
remainder of
reported
pregnancy
Comparators
Clinical
Outcomes
Oscillometric
(automated)
devices
Mercury
sphygmomanometer
Mean BP
Oscillometric
(automated)
devices
Ausculatory
(manual) devices
Mean BP
Automated
(Omron HEM705 CP)
devices, n=110
Mercury
sphygmomanometer,
n=110
Number of
women
having
episode of
severe
hypertension
Maternal
outcomes
Fetal
outcomes
Myers et al.
14
2011
Multi-site
cluster RCT
Canada
Public funding
Lamarre-Cliché
15
et al. 2011
Canada
Source of
funding: not
reported
RCT,
crossover
Patients (>45
years) with systolic
hypertension and
no serious
comorbidities,
N=555
Hypertensive
patients (mean age
58 years)
Length of
study: 8-14
days
Automated
office blood
pressure device
(BpTRU),
n=303
Manual blood
pressure device,
n=252
Automated
office blood
pressure device
(BpTRU),
n=101
Office mercury
sphygmomanometer
Mean BP
Mean BP
Mean BP
Target BP
24-hour ambulatory
Daytime ambulatory
Self-measurement
BP=blood pressure; RCT=randomized controlled trial
Mercury versus Non-Mercury Sphygmomanometers
12
APPENDIX 3: Grading of Recommendations and Levels of Evidence
Guideline
Society or
Institute
Recommendation
National
Institute for
Health and
Clinical
Excellence
(NICE), UK,
16
2011
Cincinnati
Children’s
Hospital
Medical Center.
Best evidence
statement,
17
2009
The Center established a Guideline Development Group, which reviewed the evidence and
updated the recommendations. An independent Guideline Review Panel oversaw the updating of
the guideline. For more information, see WWW.nice.org.uk/HowWeWork
Society of
Obstetric
Medicine of
Australia and
New Zealand
(SOMANZ)
18
2008
Society of
Obstetricians
and
Gynaecologists
of Canada
Magee et al.
19
2008
Level of Evidence
“Strongly recommended”: There is
consensus the benefits clearly outweigh risks
and burdens (or visa-versa for negative
recommendations)
“Recommended”: There is consensus that
benefits are closely balanced with risks and
burdens
No recommendation made: There is a lack of
consensus to direct development of a
recommendation
Not indicated
1a or 1b: Systematic review, meta-analysis, or
meta-analysis of multiple studies
2a or 2b: Best study design for domain
3a or 3b: Fair study design for domain
4a: or 4b: Weak study design for domain
5: Other: General review, expert opinion, case
report, consensus report, or guideline
A. There is good evidence to recommend
the clinical preventive action
B. There is fair evidence to recommend the
clinical preventive action
C. the existing evidence is conflicting and
does not allow to make a
recommendation for or against use of the
clinical preventive action; however, other
factors may influence decision-making
D. There is fair evidence to recommend
against the clinical prevention action
E. There is good evidence to recommend
against the clinical prevention action
I. There is insufficient evidence (in quantity
or quality) to make a recommendation;
however, other factors may influence
decision-making
I: Evidence obtained from at least one properly
randomized controlled trial
II-1: Evidence from well-designed controlled trials
without randomization
II-2: Evidence from well-designed cohort
(prospective or retrospective) or case-control
studies, preferably from more than one centre or
research group
II-3: Evidence obtained from comparisons
between times or places with or without the
intervention. Dramatic results in uncontrolled
experiments (such as results of treatment with
penicillin in 1940s) could also be included in this
category
III: Opinions of respected authorities, based on
clinical experience, descriptive studies, or reports
of expert committees
Mercury versus Non-Mercury Sphygmomanometers
a = good quality study; b = lesser quality study
Not indicated
13
APPENDIX 4: Summary of Study Strengths and Limitations
First Author,
Publication Year
Strengths
Systematic Reviews and Meta-analyses
11
Stergiou et al. 2012
Scored “Yes” on 9 out of 11 items of the
AMSTAR checklist (1-6, 9-11)
12
Skirton et al. 2011
Scored “Yes” on 8 out of 11 items of the
AMSTAR checklist (1, 3-8, 11)
Limitations
Scored “No” on 2 out of 11 items of the
AMSTAR checklist (7, 8). List of excluded
studies not provided
Scored “No” on one item (10), “Can’t tell” on
one item (2), and “Not applicable” on one
item (9)
AMSTAR check list
1. Was an “a priori” design provided?
2. Was there duplicate study selection and data extraction?
3. Was a comprehensive literature search performed?
4. Was the status of publication (i.e., grey literature) used as an inclusion criteria?
5. Was a list of studies (included and excluded) provided?
6. Were the characteristics of the included studies provided?
7. Was the scientific quality of the included studies assessed and documented?
8. Was the scientific quality of the included studies used appropriately in formulating conclusions?
9. Were the methods used to combine the findings of studies appropriate?
10. Was the likelihood of publication bias assessed?
11. Was the conflict of interest stated?
Randomized controlled trials
13
Brown et al. 2012
Hypothesis/objective, main outcomes to
A list of principal confounders was not
be measured, characteristics of
provided
included patients, interventions of
The characteristics of patients lost to followinterest and the main findings were
up were not described
explicit
Attempt was made to blind study subjects
The study provided mean and standard
(not applicable in this study)
deviation or percentage for outcomes
Unable to determine compliance with the
All important adverse events were
interventions
reported
Random assignment was not concealed
The actual p-values were reported
from staff
The recruited subjects represented the
Unable to determine if there was adequate
entire population within a specified
adjustment for confounding in the analyses,
period of time
or losses of patients to follow-up were taken
Staff, places and facilities where
into account
patients were treated, were
representative of the treatment the
majority of patients received
Attempt was made to blind those
measuring the main outcomes of the
intervention.
Follow-up was the same for all study
patients
Statistical tests used to assess the main
outcomes were appropriate
The outcome measures were clearly
described
Patients in both groups were recruited
from the same population, over the
same period of time, and were
randomized to the interventions groups
The trial was powered to detect the
difference in primary outcome
14
Myers et al. 2011
Hypothesis/objective, main outcomes to
A list of principal confounders was not
be measured, characteristics of
provided
Mercury versus Non-Mercury Sphygmomanometers
14
First Author,
Publication Year
Lamarre-Cliché et al.
15
2011
Guidelines
National Institute for
Health and Clinical
Strengths
included patients, interventions of
interest and the main findings were
explicit
The study provided mean differences
and 95% confidence intervals for
outcomes
The actual p-values were reported
The recruited subjects represented the
entire population within a specified
period of time
Staff, places and facilities where
patients were treated, were
representative of the treatment the
majority of patients received
Follow-up was the same for all study
patients
Statistical tests used to assess the main
outcomes were appropriate
The outcome measures were clearly
described
Patients in both groups were recruited
from the same population, over the
same period of time, and were
randomized to the interventions groups
The trial was powered to detect the
difference in primary outcome
Hypothesis/objective, main outcomes to
be measured, characteristics of
included patients, interventions of
interest and the main findings were
explicit
The study provided mean differences
and 95% confidence intervals for
outcomes
The actual p-values were reported
The recruited subjects represented the
entire population within a specified
period of time
Staff, places and facilities where
patients were treated, were
representative of the treatment the
majority of patients received
Follow-up was the same for all study
patients
Statistical tests used to assess the main
outcomes were appropriate
The outcome measures were clearly
described
Patients in both groups were recruited
from the same population, over the
same period of time, and were
randomized to the interventions groups
The trial was powered to detect the
difference in primary outcome
Objectives and target patients
population were explicit.
Mercury versus Non-Mercury Sphygmomanometers
Limitations
All important adverse events were not
reported
The characteristics of patients lost to followup were not described
No attempt was made to blind study
subjects (not applicable in this study)
No attempt was made to blind those
measuring the main outcomes of the
intervention.
Unable to determine compliance with the
interventions
Random assignment was not concealed
from staff
Unable to determine if there was adequate
adjustment for confounding in the analyses,
or losses of patients to follow-up were taken
into account
A list of principal confounders was not
provided
All important adverse events were not
reported
The characteristics of patients lost to followup were not described
No attempt was made to blind study
subjects (not applicable in this study)
No attempt was made to blind those
measuring the main outcomes of the
intervention.
Unable to determine compliance with the
interventions
Random assignment was not concealed
from staff
Unable to determine if there was adequate
adjustment for confounding in the analyses,
or losses of patients to follow-up were taken
into account
The guidelines are not supported with
application tools
15
First Author,
Publication Year
Strengths
Excellence (NICE),
16
UK, 2011
A procedure for updating the guideline
was provided
The recommendations were specific
and unambiguous
Key recommendations were easily
identified
The editorial independence of the
guidelines was specified.
Cincinnati Children’s
Hospital Medical
Center. Best evidence
17
statement, 2009
Objectives and target patients
population were explicit.
The recommendations were specific
and unambiguous
Key recommendations were easily
identified
Society of Obstetric
Medicine of Australia
and New Zealand
18
(SOMANZ) 2008
Objectives and target patients
population were explicit.
The recommendations were specific
and unambiguous
Society of
Obstetricians and
Gynaecologists of
Canada
19
Magee et al. 2008
Objectives and target patients
population were explicit.
The recommendations were specific
and unambiguous
Key recommendations were easily
identified
Formulation of the recommendations
was based on clinical evidence
Mercury versus Non-Mercury Sphygmomanometers
Limitations
The cost implication of applying these
guidelines was not evaluated and reported.
The recommendations were based on
consensus of appraisal committee
members, who considered evidence from a
number of sources including systematic
reviews, assessment reports and
manufacturers documents.
Patient’s preferences and views were not
explicitly taken into consideration.
Methods used for searching the evidence
were not reported.
The guidelines are not supported with
application tools
A procedure for updating the guideline was
not provided
The cost implication of applying these
guidelines was not evaluated and reported.
Formulation of the recommendations was
based on expert consensus.
Patient’s preferences and views were not
explicitly taken into consideration.
Methods used for searching the evidence
were not reported.
The editorial independence of the guidelines
was not specified.
The guidelines are not supported with
application tools
A procedure for updating the guideline was
not provided
The cost implication of applying these
guidelines was not evaluated and reported.
Formulation of the recommendations was
based on literature reviews and expert
consensus.
Patient’s preferences and views were not
explicitly taken into consideration.
Methods used for searching the evidence
were not reported.
The editorial independence of the guidelines
was not specified.
Key recommendations were not easily
identified
The guidelines are not supported with
application tools
A procedure for updating the guideline was
not provided
The cost implication of applying these
guidelines was not evaluated and reported.
Patient’s preferences and views were not
explicitly taken into consideration.
Methods used for searching the evidence
were not reported.
The editorial independence of the guidelines
was not specified.
Financial disclosures and conflict of interest
were not stated.
16
APPENDIX 5: Main Study Findings and Authors’ Conclusions – Clinical
First
Author,
Publication
Year,
Country
Main Findings
Systematic Review
Correlation coefficient between automated and manual SBP/DBP (4 studies):
Stergiou et al.
11
2012
For SBP: r=0.89, 95% CI 0.84, 0.94
For DBP: r=0.76, 95% CI 0.70, 0.81, p<0.001 for difference
Average blood pressure differences between automated and manual method (6 studies):
SBP difference = 0.5 mm Hg, 95% CI -0.9, 1.9
DBP difference = 2.5 mm Hg, 95% CI -0.6, 5.7
Absolute blood pressure differences within 5 mm Hg
Four of eight studies reporting data regarding the within 5 mm Hg ESH-IP criterion have passed
for SBP (at least 65% of comparisons within 5 mm Hg) and only two for DBP
Impact of heart rate
Heart rate had no impact on the blood pressure differences between automated and manual
measurements
Authors’ Conclusions: “this analysis suggests that the currently available automated blood pressure monitors that
have been validated in individuals with sinus rhythm appear to be accurate in measuring systolic blood pressure but
not diastolic blood pressure in individuals with sustained atrial fibrillation” p.8
Skirton et al.
12
2011
Study
Intervention vs. control Population
Main findings
CrossAutomated (BpTRU) vs.
50 patients in a
Results suggested that the
UK
sectional
manual (mercury)
hypertension or
automated device should
survey
internal
replace manual instruments in
medicine clinic
clinical practice and research
CrossAutomated (Dinamap)
47 hospital
Dinamap demonstrably less
sectional
vs. manual (mercury)
patients
accurate than mercury
sphygmomanometer, especially
systolic pressure (p<0.05)
Prospective
Automated (Dinamap)
171 patients in
The automated device
Crossvs. manual (mercury)
emergency
consistently overestimated
sectional
department
systolic BP and underestimated
study
diastolic BP
CrossAutomated BP wrist
85 participants
Wrist device readings are more
sectional
monitor (Omron Rx) vs.
closely correlated with mercury
manual (mercury)
sphygmomanometer readings
using appropriately sized cuffs.
Retrospective Automated (Dinamap)
388 trauma
Manual BP readings were more
crossvs. manual (mercury)
patients
reflective of patient condition.
sectional
Automated BP measurements
study
were higher than manual
readings, especially in
hypotensive patients
Prospective
Automated (Dinamap)
85 participants
The automated device is
cohort study
vs. manual (mercury)
(outpatients or
acceptable for clinical use,
staff of a large
according to BHS criteria
teaching
hospital)
CrossAutomated (Omron R3
85 patients
All three types of devices
sectional
and Visomat OZ2) vs.
attending a
showed good reproducibility.
quasimanual (mercury)
medical
Automated devices performed
Mercury versus Non-Mercury Sphygmomanometers
17
First
Author,
Publication
Year,
Country
Main Findings
experimental
outpatient clinic
Crosssectional
aneroid and oscillometric
vs. manual (mercury)
500 participants
from
Hypertension
Center,
Preventive
Medicine
Research
Center and local
fairs
Post-hoc
analysis of
observational
Prospective
cohort
Automated (OMRON 705
CP) vs. manual
(mercury)
Automated (Dinamap
Pro-care 400) vs. manual
(mercury)
313 untreated
hypertensive
patients
300 patients at
one tertiary care
teaching
hospital
Prospective
cohort
Automated (TM-2564G)
vs. sphygmomanometer
85 inpatients
from one
hospital
Prospective
crosssectional
aneroid Welch Allyn
Tycos 767 vs. manual
(mercury)
997 participants
at high risk of
diabetes
Prospective
crosssectional
Automated (BpTRU) vs.
manual (mercury)
238 Ontario
residents
Prospective
cohort
Automated (Dinamap
Pro-care) vs. manual
(mercury)
33 outpatients
Mercury versus Non-Mercury Sphygmomanometers
less well than mercury
sphygmomanometer in
hypertensive patients.
Measuring BP on the wrist
using automated devices was
not found to be satisfactory
Oscillometric device slightly
overestimated systolic BP and
underestimated diastolic BP
compared with mercury
sphygmomanometer.
Oscillometric device was
comparable in performance to
the aneroid device, and both
could be used to replace the
mercury manometer
There are differences between
readings obtained by both
devices.
Authors state ‘reasonable good
correlation’ between the two
devices for systolic and
diastolic pressure. Some
observer bias noted when
mercury manometer was used
notably repeated measure and
terminal digit bias. Interoperator measurements were
more consistent for the
automated device than intraoperator measurements using
the mercury device
Diastolic readings taken with
the device did not differ more
than 5 mmHg from those taken
with the sphygmomanometer.
99.2% of the systolic readings
taken with the device were
within 5 mmHg of
sphygmomanometer
There were no clinically
significant differences between
readings according to the type
of sphygmomanometer
Mean BP taken with automated
device was lower than that
taken with mercury
sphygmomanometer. Authors
conclude the BpTRU able to be
used because it reduced white
coat effect
79% of measurements with
device were within 5 mm Hg of
the systolic reading taken with
18
First
Author,
Publication
Year,
Country
Main Findings
mercury, while 77% of diastolic
readings were within 5 mmHg.
The device is acceptable for
clinical use, according to the
Advancement of Medical
Instrumentation
Prospective
Automated (OMRON) vs. 907
99% readings by traditional
sphygmomanometer
hypertensive
nurses ended in zero. Using a
patients
level of plus and minus 5 mm
Hg, traditional nurse over
estimated systolic BP in 45%
cases and underestimated
systolic BP in 26.5% cases.
Automated device
overestimated systolic BP in
51.3% cases and
underestimated systolic BP in
12% cases
Randomized
Automated (IVAC 4200)
145 stable
IVAC measurements are less
controlled
vs. manual (mercury)
inpatients
than satisfactory in both systolic
trial
and diastolic BP. Arrhythmia or
low K5 reduces IVAC accuracy.
IVAC should not be used for
patients with hypertension
Authors’ Conclusions: “There are situation where the substitution of oscillometric for auscultatory devices could
have particularly serious repercussions for the patient, such as when the patient is either hypertensive or
hypotensive. However, further research is required on the use of aneroid sphygmomanometers as a replacement for
mercury devices” p.602
Randomized controlled trials
Blood pressures obtained by six sequential recordings (alternating between mercury and
Brown et al.
13
automated)
2012
Mercury
Automated
(n=110)
(n=110)
Average BP using mercury manometer (mm Hg)
139 (9) / 90 (7)
137 (9) / 91 (7)
Average BP using automated device (m Hg)
136 (12) / 86 (8)
137 (11) / 87 (8)
Difference in average BP (mm Hg)
2 (8) / 3 (6)
1 (7) / 5 (5)
Average SBP difference between methods (%)
55
56
≤5 mm Hg
80
90
≤10 mm Hg
96
96
≤15 mm Hg
Average DBP difference between methods (%)
60
63
≤5 mm Hg
88
92
≤10 mm Hg
97
99
≤15 mm Hg
Maternal and fetal outcomes were similar between groups.
Mercury
Gestation at last antenatal visit (weeks)
Gestation at birth (weeks)
Diagnosis at birth (%)
Essential hypertension
Mercury versus Non-Mercury Sphygmomanometers
Automated
37 (2)
38 (3)
37 (2)
37 (3)
pvalue
0.1
0.08
15
14
0.96
19
First
Author,
Publication
Year,
Country
Main Findings
Gestational hypertension
Preeclampsia
Onset of labor (%)
Spontaneous
Induction of labor
Nil
Mode of birth (%)
Normal vaginal birth
Instrumental
Lower segment caesarean section
Gestational diabetes (%)
Maternal antenatal transfer (n)
Antihypertensive medications at birth (%)
Women with any episodes of severe hypertension (%)
Average number of episodes of severe hypertension per
woman affected
Birth weight (grams)
th
Small for gestational age (<10 centile) (%)
Premature (<37 weeks) (n)
Transfer to NICU (%)
Perinatal mortality (n)
39
46
38
48
63
11
26
51
23
26
0.052
39
15
46
12
3
90
39
3 (2)
46
13
41
7
4
85
44
4 (5)
0.552
3014 (780)
12
30
4
1
2890 (712)
17
38
4
1
0.2
0.3
0.1
1
1
0.3
0.7
0.2
0.5
0.3
Percentage of women with any episode of severe hypertension was similar between groups
(39% for mercury vs. 44% for automated, p=0.5)
Average number of episodes of severe hypertension per woman affected was similar
between groups (3±2 for mercury vs. 4±5 for automated, p=0.3)
Authors’ Conclusions: “This study showed that there are similar maternal and fetal outcomes when BP is measured
by either routine mercury sphygmomanometer or the Omron HEM-705CP automated BP device after the initial
detection of hypertension by mercury sphygmomanometer in pregnant women” p.117
Mercury versus Non-Mercury Sphygmomanometers
20
First
Author,
Publication
Year,
Country
Main Findings
Myers et al.
14
2011
Mean (SD) blood pressure (BP) taken in physicians’ office before and after enrolment into
study and baseline mean awake ambulatory BP recorded between two office visits
Canada
Measurement
Last routine office BP
Office BP after enrolment
Difference from last routine
Awake ambulatory
Difference from last routine
Difference from post-enrolment
Automated (n=299)
149.5 (10.8)/81.4 (8.3)
135.6 (17.3)/77.7 (10.9)
-13.9 (-11.8, -16.1)***/
-3.7 (-2.5, -4.8)***
133.2 (12.4)/74.4 (9.8)
-16.3 (-14.5, -18.1)***/
-7.0 (-5.8, -8.1)***
-2.3 (-0.31 to -4.3)*/
-3.3 (-2.2 to -4.4)***
Manual (n=249)
149.9 (10.7)/81.8 (8.5)
141.4 (14.6)/80.2 (9.5)
-8.5 (-6.5, -10.4)***/
-1.6 (-0.4, -2.8)**
135.0 (13.1)/75.9 (10.0)
-14.9 (-12.9, -17.0)***/
-5.9 (-4.6, -7.2)
-6.5 (-4.3, -8.6)***/
-4.3 (-2.9, -5.8)***
*p=0.02
**p=0.01
***p<0.001
Coefficients of correlation between office systolic/diastolic BP readings and mean awake
ambulatory BP
Measurement
Last routine vs. awake ambulatory
After enrolment vs. awake
ambulatory
Estimated mean difference (95%
CI) in r from before to after
enrolment
*p<0.001
**p=0.03
Automated
r=0.10 / r=0.40
r=0.34 / r=0.56
Manual
r=0.04 / r=0.42
r=0.22 / r=0.30
0.24 (0.12, 0.36)*/
0.16 (0.07, 0,25)*
0.18 (0.02, 0.32)**/
-0.12 (-0.01, 0.24)
Authors’ Conclusions: “In compliant, otherwise healthy, primary care patients with systolic hypertension,
introduction of automated office blood pressure measurement into routine primary care significantly reduced the white
coat response compared with the ongoing use of manual office blood pressure measurement. The quality and
accuracy of automated office blood pressure in relation to the awake ambulatory blood pressure was also significantly
better when compared with manual office blood pressure.” p.1
Lamarre-Cliché
15
et al. 2011
Average Blood Pressure
Mean ± SD
Canada
Sphygmomanometer
129.9 ± 13.7 / 80.9 ± 9.3
AOBP (BpTRU)
128.4 ± 13.9 / 80.0 ± 9.4
24-hour ABPM
131.4 ± 11.7 / 78.7 ± 9.7
Daytime ABPM
135.5 ± 11.4 / 82.0 ± 11.9
Self-Measurement
131.0 ± 14.3 / 82.5 ± 8.2
Differences between methods
Sphygmomanometer vs. BpTRU
1.45 ± 7.59 / 0.84 ± 5.05
Sphygmomanometer vs. 24-hour ABPM
-1.29 ± 11.85 / 2.30 ± 7.59**
Sphygmomanometer vs. daytime ABPM
-5.43 ± 12.12*** / 0.98 ± 7.55
Sphygmomanometer vs. self-measurement
-1.11 ± 14.05 / -1.56 ± 8.50
BpTRU vs. 24-hour ABPM
-2.76 ± 12.56* / 1.39 ± 7.09
BpTRU vs. daytime ABPM
-6.90 ± 12.86*** / -1.90 ± 6.90**
BpTRU vs. self-measurement
-2.56 ± 15.25 / -2.41 ± 8.02**
24-hour ABPM vs. self-measurement
0.34 ± 10.09 / -3.66 ± 7.88***
Daytime ABPM vs. self-measurement
4.48 ± 11.24*** / -0.38 ± 8.30
ABPM=ambulatory blood pressure measurement; AOBP=automated office blood pressure
*p<0.05
**p<0.01
***p<0.001
Target BP 140/90 mm Hg: 67% with office sphygmomanometer; 70& with AOBP
Mercury versus Non-Mercury Sphygmomanometers
21
First
Author,
Publication
Year,
Country
Main Findings
Target BP 135/85 mm Hg: 52% with self-measurement; 43% with daytime ABPM readings
Target 130/80 m Hg: 37% with 24-hour ABPM
Authors’ Conclusions: “This study shows that sphygmomanometer, AOBP, ABPM, and self-measurement provide
similar average blood pressure estimates but generate many discordant results on an individual basis. The AOBP is a
new office measurement device that offers specific advantages but has diagnostic properties that are highly
dependent on chosen diagnostic thresholds” p. 459
Mercury versus Non-Mercury Sphygmomanometers
22
APPENDIX 6: Guidelines and Recommendations on Use of Device for Blood Pressure
Measurement
Guideline Society,
Country, Author,
Year, Indication
Recommendations
National Institute for
Health and Clinical
Excellence (NICE), UK,
16
2011
“Because automated devices may not measure blood pressure accurately if there is
pulse irregularity (for example, due to atrial fibrillation), palpate the radial or brachial
pulse before measuring blood pressure. If pulse irregularity is present, measure blood
pressure manually using direct auscultation over the brachial artery” p.10
Clinical Management of
primary hypertension in
adults
“Healthcare providers must ensure that devices for measuring blood pressure are
properly validated, maintained and regularly recalibrated according to manufacturers’
instructions” p.10
Cincinnati Children’s
Hospital Medical Center.
Best evidence
17
statement, 2009
Blood pressure
Measurement in Children
Society of Obstetric
Medicine of Australia
and New Zealand
18
(SOMANZ) 2008
Management of
Hypertensive Disorders
of Pregnancy
Society of Obstetricians
and Gynaecologists of
Canada
19
Magee et al. 2008
Diagnosis, evaluation
and management of the
hypertensive disorders of
pregnancy
“If using an automated blood pressure monitoring device, ensure that the device is
validated and appropriate cuff size for the person’s arm is used” p.11
“It is recommended that auscultation with mercury or aneroid sphygmomanometer be
used for diagnostic evaluation of blood pressure evaluation [5]” p.1
“Note 1: Blood pressure measurement with an oscillometric device may be
acceptable for routine surveillance [5]. An elevated blood pressure reading obtained
with an oscillometric device should be repeated using auscultatory method [5]” p.1
“Note 2: Use of automated devices may be necessary for blood pressure
measurement in newborns and young infants, in whom auscultation may be difficult
[5]” p.1
“Mercury sphygmomanometers remain the gold standard for measurement of blood
pressure in pregnancy however occupational health concerns are limiting their
availability” p.4
“Each unit should maintain a mercury sphygmomanometer for validation of automated
and aneroid devices” p.4
“All devices should be calibrated on a regular basis (ideally monthly), as recommended
by the British Hypertension Society” p.4
“BP can be measured using a mercury sphygmomanometer, calibrated aneroid device,
or an automated BP device that have been validated for use in preeclampsia. (II-2A)
Automated BP machines may underestimate BP in women with preeclampsia, and
comparison of readings using mercury sphygmomanometer or an aneroid device is
recommended. (II-2A)
Ambulatory BP monitoring (by 24-hour or home measurement) may be useful to detect
isolated office (white coat) hypertension. (II-2B)” p.S9
Mercury versus Non-Mercury Sphygmomanometers
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