Measuring Accuracy Of Blood Pressure Devices

Importance of accurate blood pressure measurement

Increase in blood pressure or hypertension is an important risk factor consideration the health of the population. It not only increases the overall risk of coronary heart disease, haemorrhagic and ischemic shock, but also it increases the risk of developing other cardiac complications along with renal impairment and visual impairment (Joffres et al. 2018). Shahbabu et al. (2016) stated that accurate detection of the blood pressure on time helps to reduce the overall chances of developing cardiovascular complications. Myers et al. (2014) highlighted that measurement of blood pressure helps in drafting proper interventions and thereby helping to maintain blood pressure within the normal range (140/90 mm of Hg). There are two common techniques used in the measurement of blood pressure one is the conventional sphygmomanometer (manual) and another one is automated blood pressure machine. According to the Australian Institute of Health and Welfare (2017), 2 out of 3 Australians who are above 40 years of age suffer from hypertension. In spite of the advent of automation in measurement of the blood pressure ease of access, in Australia, the use of sphygmomanometer (manual) is high in comparison to the digital or automated blood pressure recording (Toohey, Noronha & Nunes 2017). The following research proposal is based on the analysis of the measuring accuracy of blood pressure devices (sphygmomanometer (manual) and automated blood pressure machine) under the medical and surgical settings of Royal Prince Alfred Hospital of New South Wales.

Royal Prince Alfred Hospital is a premier tertiary referral hospital. It is a part of network hospitals within Sydney Local Health District. It is also the principal teaching hospital of the University of Sydney. This referral hospital is flooded with patients and emergency admission or admission in surgical or medical  ward demands recording of the vital signs and of them blood pressure in an important factor (Smith et al. 2013). Parati et al. (2014) highlighted that rise in the systolic BP by 5 mm of Hg results in 25% increase in the probability of fatal stroke or myocardial infarction. These findings emphasize the catastrophic consequences underlying the requirement of accurate blood pressure. Parati et al. (2014) further highlighted that over-estimation of the original blood pressure by same level will result in improper treatment with anti-hypertension medications. This in turn increases the risk of adverse drug affect along with psychological effect of misdiagnosis and unnecessary cost to the overall disease. In order to ascertain the curacy of the blood pressure measurement, Shahbabu et al. (2016) conducted a comparative study between digital and aneroid sphygmomanometer. The result of this comparative study highlighted that accuracy of aneroid device is higher than the accuracy of the digital devices. However, the comparative study was conducted with high sample size (218 subjects), but the target population mainly OPD (outpatient department) patients. Parati et al. (2014) highlighted that proper tabulation of the blood pressure is more crucial in the medical and surgical ward especially among the cardiac patients. Taksande, Jadhav and Vagha (2015) conducted comparative study in order to ascertain the measuring efficacy of automated and manual sphygmomanometer among pediatric population. Their comparative study mainly included 100 children and four consecutive blood pressure was recorded (two systolic and two diastolic). The analysis of the findings highlighted that automate blood pressure measuring device is more accurate in comparison to the manual mercury based blood pressure recorded (Taksande, Jadhav & Vagha 2015). Study conducted by automated blood pressure recorder with model number (A&D UA-767PC) is not good enough in comparison to the manual blood pressure recording device. They mainly conducted the study over the 454 subjects with the mean age of 50.74 (+/- 15.4 years). Thus this study again provided the different results in comparison to study conducted by Taksande, Jadhav and Vagha (2015) however, the target population was different.

Common techniques used in the measurement of blood pressure

Thus it can be seen that the readings or the efficacy results of the blood pressure measuring device (both digital and manual) differs in different population and in different study. Moreover, there are no significant studies conducted in order to measure the efficacy of the digital and manual blood pressure recording device over the cardiac population whose day-to-day blood pressure monitoring is vital. Thus, the rationale of proposing this research proposal is justified. The research proposal is crucial under present day medical condition of Australia as the result evolving from the subsequent research will help to adapt accurate blood pressure measuring device. The use of accurate blood pressure measuring device will help in effective management and monitoring of the cardiac problems.

The research proposal aims to draw a comparison between manual mercury sphygmomanometer and automated blood pressure machine, for accurate measurement of blood pressure in the surgical and medical ward of Royal Prince Alfred Hospital, NSW.

Research design

The study will encompass a cross-sectional research design that will be held in the medical and surgical units of the Royal Prince Alfred Hospital. Observational studies emphasise on drawing inferences from a sample representative of a certain population, in which the independent variable is not controlled by the researcher. The cross-sectional design that is intended to be adopted in this regard is a type of observational study that will primarily emphasise on analysing data from the patient population, representative of the larger population (Aiken et al. 2014). One primary benefit of selecting a cross-sectional approach, in place of case-control design can be attributed to the fact that the latter only comprises of people having specific characteristics, rather than the entire population. This study design will measure the exposure to the intervention (either automated blood pressure machine or manual mercury sphygmomanometer) and the subsequent outcome (accurate blood pressure reading), simultaneously for all the subjects. The rationale behind conducting cross-sectional study is that the entire study can be completed in a relatively shorter timeframe (Von Elm et al. 2014). Furthermore, routine collection of data will facilitate the study conduction at little expense.

Sample

In the medical and surgical wards of the Royal Prince Alfred Hospital, subjects above the age of 40 years, will be selected randomly from three working days per week. This randomisation process will be conducted over a period of two months (December 2018-February 2019). The age criteria will be selected above 40 years owing to the high risks of hypertension among people belonging to that age group. Both males and females, with or without any previous history of abnormal blood pressure will be eligible for participation in the study. Exclusion criteria of the patients will comprise of presence of bruises or cut marks at the site of blood pressure measurement, or amputation in the upper limb. Total 30 patients will be recruited for the purpose. The participants will be subjected to blood pressure measurement by a manual mercury sphygmomanometer (NOVAPHON), and an automated sphygmomanometer (UA-767S).

Analysis of the accuracy of blood pressure measuring device

Data collection

All the instruments to be used for checking the blood pressure will be calibrated, checked and standardised by nursing experts. An approval will be taken from the Institutional Ethics Committee, followed by informed consent of the participants, prior to data collection. The participants will be seated by supporting their back and the left arm will be kept at the heart level. They will be allowed to rest for a while, before the measurements are taken. The manual mercury sphygmomanometer will be first used for determining the systolic estimate. The cuff will be inflated until there is no palpation. The cuff will again be inflated till 30 mmHg, followed by a release at 2 mmHg/second, until reappearance of the radial pulse (Li-wei et al. 2013). This value is the systolic estimate. Inflating the cuff to levels higher than the systolic estimate, and deflating it at 2 mmHg/second will produce Korotkoff sounds. While the 1^st sound will represent the systolic pressure, the 5^th will denote the diastolic pressure. The pressures will be noted for each patient. This will be followed by a 3-minute break.

The automated sphygmomanometer will be based on an inflate technology where a pumping system will drive the inflation and an electromagnetic control will govern the deflation. Upon pressing the ‘start’ button, blood pressure measurement will commence on the UA-767S machine. The digitally displayed records for systolic and diastolic pressure will be again noted for all patients (Leung et al. 2016). Both the manual and automated devices will be positioned in a way that the patients are not able to see the readings.

Average of the two recordings will be calculated for all participants. SPSS-21.0 statistical software will be put to use for calculating the mean and the standard deviations. Histograms will be drawn for demonstrating the mean automated and manual BP systolic and diastolic values. Paired t-tests will be conducted for assessing the differences between the two instrument readings (DiMaggio 2013). This will be followed by a linear regression analysis that will determine the association between the manual and automated readings, with automated BP as the independent variable.

Limitations

The primary limitation of this study can be associated with conduction of the study in medical and surgical wards only, thus comprising of patients who came there to seek medical advice. This might lead to bias in sample selection, due to failure to include community members. Secondly, using only one model each of the two types of sphygmomanometers would not help in determining the overall effectiveness of manual and automated blood pressure monitoring devices. Furthermore, the study will be conducted only in Royal Prince Alfred Hospital, for two months. Taking into consideration the role of climate in altering blood pressure, a bias might be obtained in the results as well. 

Research proposal and study design

References

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Australian Institute of Health and Welfare (2017). ‘Risk Factors to Health’. Access date: 1^st September 2018. Retrieved from: https://www.aihw.gov.au/reports/biomedical-risk-factors/risk-factors-to-health/contents/high-blood-pressure

DiMaggio, C., 2013. ‘Introduction’, In SAS for Epidemiologists (pp. 1-5). Springer, New York, NY.

Joffres, M., Falaschetti, E., Gillespie, C., Robitaille, C., Loustalot, F., Poulter, N., … & Campbell, N. 2013, ‘Hypertension prevalence, awareness, treatment and control in national surveys from England, the USA and Canada, and correlation with stroke and ischaemic heart disease mortality: a cross-sectional study’, BMJ open, vol. 3, no. 8, pp. e003423.

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Lim, Y.H., Choi, S.Y., Oh, K.W., Kim, Y., Cho, E.S., Choi, B.Y., Kim, Y.M. &Shin, J., 2013, ‘Comparison between an automated device and a manual mercury sphygmomanometer in an epidemiological survey of hypertension prevalence’, American journal of hypertension, vol. 27, no. 4, pp.537-545.

Li-wei, H.L., Saeed, M., Talmor, D., Mark, R. & Malhotra, A., 2013, ‘Methods of blood pressure measurement in the ICU’, Critical care medicine, vol.41, no.1, p.34.

Myers, M.G., Kaczorowski, J., Dawes, M. & Godwin, M., 2014, ‘Automated office blood pressure measurement in primary care’, Canadian Family Physician, vol. 60, no. 2, pp.127-132.

Parati, G., Stergiou, G., O’brien, E., Asmar, R., Beilin, L., Bilo, G., Clement, D., De La Sierra, A., De Leeuw, P., Dolan, E. & Fagard, R., 2014, ‘European Society of Hypertension practice guidelines for ambulatory blood pressure monitoring’, Journal of hypertension, vol. 32, no. 7, pp.1359-1366.

Royal Prince Alfred Hospital. (2018). ‘About Us’. Access date: 1^st September 2018. Retrieved from: https://www.slhd.nsw.gov.au/rpa/services.html 

Shahbabu, B., Dasgupta, A., Sarkar, K. &d Sahoo, S.K., 2016, ‘Which is more accurate in measuring the blood pressure? A digital or an aneroid sphygmomanometer’, Journal of clinical and diagnostic research: JCDR, vol. 10, no. 3, pp.LC11.

Smith, G.B., Prytherch, D.R., Meredith, P., Schmidt, P.E. & Featherstone, P.I., 2013, ‘The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death’, Resuscitation, vol. 84, no. 4, pp.465-470.

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