Home sphygmomanometers

1
Home sphygmomanometers

• Tekin AKPOLAT, MD
• Professor of Internal Medicine
• Ondokuz Mayis University School of Medicine
• Department of Nephrology
• SAMSUN-TURKEY
• November 21, 2009 ANTALYA

2
Plan

• Introduction
• Home sphygmomanometers and features
• Validation protocols
• Limitations of the validation protocols
• Accuracy of sphygmomanometers
• Potential role of nephrologists
• Conclusions/Summary
• References

3
Purpose of this presentation

• Summarize basic features of automated home BP
  measurement devices
• Emphasize the distinction between validation,
  calibration and accuracy of automated home
  sphygmomanometers
• Discuss some practical points for improvement of
  BP control in CKD for nephrologists.

4
Other topics

• Aneroid and mercury sphygmomanometers
• Proper patient preparation
• Patient training
• BP measurement techniques
• Potential advantages of SMBP and 24h ABPM
• Automated devices used for 24 hours ABPM or in
  hospitals will not be discussed

5
(No Transcript)
6
Current situation 1

• The introduction of inexpensive, easy-to-use, and
  automated BP measuring devices, lead to a
  widespread use of SMBP at home and SMBP at home
  became a part of clinical practice including CKD.

7
Current situation 2

• According to a nation-wide survey in 20042005 in
  Japan, 90 of clinicians recommended home blood
  pressure measurement and 77 of hypertensive
  patients have a sphygmomanometer at home.
• The proportion of patients owning a monitor has
  increased from 49 in 2000 to 64 in 2005 (USA).

8
(No Transcript)
9
Home sphygmomanometers

• Mercury, aneroid, automatic, and semi-automatic
• Mercury the gold standard
• Aneroid practical difficulties
• Automated preferred
• Measurement of BP with an automated device is a
  simple procedure.

10
Features of automated home sphygmomanometers 1

• Measurement site (upper arm, wrist, finger)
• Appropriate cuff-size
• Availability of smaller or larger sized cuffs
• One device-two cuffs
• Comfort cuff (22-42 cm)

11
Features of automated home sphygmomanometers 2

• Validation status in general population
• Validation status in special groups
• Model/type
• Accuracy

12
Features of automated home sphygmomanometers 3

• Arrhythmia detection
• Consecutive 3 measurements
• Avoidance of pumping to too high levels
• Multi-user facility
• Easy to use
• XL size display
• Infrared interface

13
Features of automated home sphygmomanometers 4

• Quick measurement
• Capacity of memory
• Modern style
• Small dimensions (suitable for traveling,
  handbags)
• Equipped with carrying bag
• Soft case
• Easy wrap cuff

14
Features of automated home sphygmomanometers 5

• Washable cuff cover
• Batteries included
• Minimum number of batteries
• Low battery indication
• Rechargeable battery pack
• Enabling PC connectability via USB cable

15
Features of automated home sphygmomanometers 6

• Software for use with a PC
• Links to PC separate printer
• With printer
• Bluetooth output to telemedicine service
  providers
• Blood pressure classification indicator
• Hypertension Indicator

16
Features of automated home sphygmomanometers 7

• Hide display function
• Advanced Positioning Sensor
• Wrist position sensor
• Voice speaks readings
• Voice speaks orders
• Automatic switch off

17
Features of automated home sphygmomanometers 8

• Fully automated deflation
• Tracking of morning hypertension
• Time and date of measurement
• Pulse rate
• Provide trend plots

18
Important/essential features

• Measurement site (upper arm, wrist, finger)
• Appropriate cuff-size
• Validation status in general population/ special
  groups
• Accuracy

19
Wrist/upper arm

• Wrist devices are popular
• Wrist diameter is little affected by obesity
• Strict attention should be paid to having wrist
  at heart level while operating the device.
• Three specific guidelines and two relevant
  websites recommend upper arm devices
• A validated finger device is not available

20
Appropriate cuff-size

• Obesity is an increasing problem
• Cuff bladder must encircle at least 80 of the
  arm.
• The manufacturer's specifications can be followed
• Recommendations AHA and BSH
• Smaller or larger cuff-sizes Extra payment

21
Validation/accuracy

• Validation protocols are objective guides
• Two useful websites
• All models/types of any trademark or company
  present in the market are not validated
• The validation protocols do not guarantee
  accuracy of a particular device for an individual
  patient

22
(No Transcript)
23
Validation protocols 1

• AAMI
• BHS
• International protocol
• Japan ISO-WG

24
Validation protocols 2

• The basis of the validation tests is the
  comparison of BP measured by the device being
  tested with measurements made by trained
  observers, using a mercury sphygmomanometer under
  control of one or two experts.
• BP should be measured with the arm supported at
  heart level after 10-15 min rest.

25
Validation protocols 3

• Indirect measurement of BP using a mercury
  sphygmomanometer is preferred, direct
  (intra-arterial) or simultaneous measurements
  have some disadvantages.
• A sequential same-arm method was used for
  comparison of tested automated and mercury
  sphygmomanometers.
• The devices are tested over a wide range of BP
  categories with a certain number of subjects in
  each category.

26
(No Transcript)
27
(No Transcript)
28
Validation in special groups 1

• The BHS protocol described validation procedures
  for special groups such as pregnant women,
  children and elderly people
• The basis of additional validation testing for
  elderly population is increased arterial
  stiffness with aging which is a manifestation of
  CKD including predialysis period

29
Validation in special groups 2

• Arterial stiffness can influence the
  correspondence between readings taken by mercury
  sphygmomanometers and oscillometric devices.
• Up to now, only one home sphygmomanometer was
  validated for dialysis patients (Blood Press
  Monit 2007 12 227-232)

30
Validation in special groups 3

• Arterial stiffness is also increased in diabetes
  mellitus which is the most common cause of CKD in
  most of the countries.
• Special patient groups such as early stages of
  CKD, diabetic nephropathy or patients having
  extraosseus/vascular calcifications may require
  specific validation tests.

31
Blood Press Monit 2002 7 313-8.
32
Blood Press Monit 2002 7 313-8.

• Gerin et al have addressed the clinically
  relevant issue of device accuracy in individual
  patients for the first time.
• They planned a theoretical study and made an
  empirical test to estimate the proportion of
  persons for whom a BP monitor validated according
  to existing BHS and AAMI standards would be
  inaccurate.

33
Blood Press Monit 2002 7 313-8.

• They have shown that errors do tend to cluster
  within persons, and by concentrating solely on
  the population mean error, the BHS and AAMI
  protocols allow the approval of monitors that are
  inaccurate for a substantial proportion of
  people.
• As a result, they concluded that under these
  validation criteria, it is possible that more
  than half of patients will have an average error
  greater than 5 mmHg, and more than one in four
  will have an average error greater than 10mmHg.

34
They proposed two stages for validation.

1. The model of the monitor in question should be
   validated at the population level.
2. The particular monitor unit should be validated
   in the physicians office for the intended user.

35
International protocol

• In order to decrease individual inaccuracy, the
  IP introduced a tertiary phase whereby the device
  was assessed according to the number of subjects
  in whom it gives accurate measurements in
  addition to its overall accuracy.

36
Blood Press Monit 2008 13 187-91

• The statistical power of three validation
  protocols (AAMI, BHS and International) have been
  compared by Friedman et al and they concluded
  that the decrease of participants from 85 to 33
  in the IP reduced its statistical power from 98
  to 70 .

37
Accuracy of sphygmomanometers 1

• Validation, accuracy and calibration are
  different and confusing concepts.
• Calibration is a procedure to control accurate BP
  measurement and it assesses a sphygmomanometer
  under in-vitro conditions.
• For automated sphygmomanometers, calibration is
  the assessment of the accuracy of the pressure
  transducer, which requires specialized equipment.

38
Accuracy of sphygmomanometers 2

• Although calibration of the pressure transducer
  is essential for an automated device, it does not
  address the accuracy of BP determination.
• Accuracy can only be determined by clinical
  testing.

39
Accuracy of sphygmomanometers 3

• The American Heart Association, American Society
  of Hypertension, Preventive Cardiovascular Nurses
  Association and European Society of Hypertension
  guidelines on SMBP emphasized the importance of
  checking monitors for accuracy in 2008.

40
Samsun experience 1

• We planned a campaign to determine the accuracy
  of home sphygomanometers in 2006.
• The findings have been published in two articles
  Blood Press 2008 17 3441 and Blood Press
  Monit 2009 14 2631..

41
Samsun experience 2

• We realized that a significant proportion of the
  devices had individual accuracy problems.
• Devices having a difference greater than 4mmHg
  were considered inaccurate.
• After learning that their newly purchased devices
  were inaccurate, most of the patients returned
  them to the retailer, who in turn forwarded them
  to the importer.

42
Samsun experience 3

• The technical service of the importer found that
  the calibration was normal in almost all of the
  devices.
• The company did not consider inaccuracy a problem
  and returned the device back to the patient.
• The patients came back, there was nothing to do.

43
Published studies/guidelines

• The devices were checked for accuracy using two
  methods in previous studies assessment of
  calibration and sequential measurement.
• The percentage of inaccurate automated devices
  was higher than 40 in all studies using the
  sequential method for the evaluation of accuracy
• This high inaccuracy rate is the evidence of
  magnitude of the individual accuracy problem.

44
Calibration/Accuracy

• Calibration and accuracy are different concepts
• Accuracy can only be determined by clinical
  testing But HOW?

45
HOW WILL THE INDIVIDUAL ACCURACY BE CHECKED?

• The cutoff value for inaccuracy began from
  greater than 3mmHg many investigators used at
  least 5mmHg, and Ali and Rouse J Hum Hypertens
  2002 16359361 considered inaccuracy an error
  of greater than 10 mmHg.
• The relevant guidelines emphasized the importance
  of checking the individual accuracy, but did not
  mention how to do it.

46
Blood Press Monit 2009 14 208-215.
47
Blood Press Monit 2009 14 208-215.

• This study described a method for the assessment
  of individual accuracy in details.
• The three pivots of this method are sequential
  measurement, the number of BP measurements and
  cutoff values for assessment.

48
Blood Press Monit 2009 14 208-215.

• The test has three stages
• Sequential measurement of BP similar to
  validation protocols (mercury, tested device,
  mercury..) was used for the first time for the
  assessment of individual accuracy.
• The tested devices were categorized into 4 groups

49
(No Transcript)
50
Potential role of nephrologists

• Recommendation for purchase of a validated device
  (trademark and model/type)
• Checking of the device of the patient for
  accuracy
• Teaching of BP measurement technique
• Observation of the patient while operating the
  device

51
Practical points

• Two useful websites
• Measurement of arm circumference
• Supplementation with CD, video, easily readable
  booklets, brochures
• The PA.NET International Quality Certification
  Protocol (Blood Press Monit 2008 13 285-9)

52
Conclusions/Summary 1

• Inaccuracy of home sphygmomanometers is a common,
  neglected and ignored problem.
• Measurement site, cuff-size, validation status,
  and accuracy are the most important features.

53
Conclusions/Summary 2

• Individual accuracy can be more important in
  special patient groups such as early stages of
  CKD, diabetic nephropathy or patients having
  extraosseus/vascular calcifications.
• The nephrology clinics have a great role and
  responsibility to encourage optimal circumstances
  for SMBP at home for their patients and they can
  be organized for training programs and check of
  individual accuracy.

54
Conclusions/Summary 3

• Active guidance of nephrologists to all steps of
  SMBP at home will improve control of BP and
  increase quality of patient care in CKD.

55
References

• http//www.dableducational.org.
• http//www.bhsoc.org/blood_pressure_list.stm
• J Hypertens 2008 26 1505-26.
• J Cardiovasc Nurs 2008 23 299-323.
• J Hypertens 1993 11 (suppl 2) S43S63.
• Blood Press Monit 2009 14 208-215.
• Blood Press Monit 2002 7 313-8.
• Blood Press Monit 2002 7 3-17.
• Hypertens Res 2003 26 771-82.

56

• If you want this presentation
• Please send an email to
• tekinakpolat_at_yahoo.com
• In 10 days