Evaluation of the Technique Used by Health-Care Workers for Taking Blood Pressure
Abstract
Abstract The precise guidelines recommended by the American Heart Association for blood pressure measurement are commonly overlooked by health-care workers, who generally take blood pressure in an arbitrary way. To validate this observation we designed a descriptive and observational study to be carried out in a major hospital. One hundred and seventy-two health-care workers divided into four groups (63 general practitioners, 25 clinical and 25 surgical specialists, and 59 nurses) were evaluated in a two-part test. In the first part (practical), the examinee had to follow all the steps recommended by the American Heart Association to get a passing score. In the second part (theoretical, which came second to avoid influencing the practical), the examinee had to answer correctly 7 of 10 questions based on the American Heart Association’s guidelines to obtain a passing score. The highest accepted variation in systolic and diastolic pressures between examinee and observer was ±4 mm Hg. None of the examinees followed the American Heart Association’s recommendations. Sixty-three percent of systolic and 53% of diastolic readings were out of range. Surgical specialists obtained the best practical results (48% systolic and 64% diastolic within range), and nurses obtained the lowest values (29% and 39%, respectively; P=.03 versus surgical specialists). These two groups showed deficiencies in the theoretical test (nurses, 10% correct answers and surgical specialists, 16%). Clinical specialists obtained the best results on the theoretical test (60% correct; P<.05 versus the other groups) but were deficient in the practical test (32% systolic and 60% diastolic within range). In conclusion, on practical and theoretical bases health-care workers took blood pressure inaccurately and incorrectly.
Arterial hypertension is one of the leading causes of cerebrovascular and cardiac morbidity. Up to 20% of adults are affected by this disorder. Thus, its control and treatment depend on proper diagnosis, in which the blood pressure (BP) measurement is a critical factor.1 Unfortunately, the way health-care workers take BP differs significantly from center to center and person to person, despite guidelines published by the American Heart Association (AHA) in 1988.2
The medical literature on the methods used for BP determination is scarce,3 4 5 6 7 8 and very few studies about the AHA recommendations have been published; therefore, we designed a descriptive study to evaluate this issue.
Methods
This was an observational and descriptive study carried out in a major hospital. One hundred and seventy-two health-care workers divided into four groups (63 general practitioners, 59 nurses, 25 clinical specialists, and 25 surgical specialists) were evaluated in a two-part test. The first part (practical) evaluated the different techniques used by the examinees to take BP, and the second part (theoretical) consisted of a 10-question test based on the AHA recommendations for BP measurement. The practical test was performed first to avoid bias on the part of the participants.
In the practical test a complete set of previously calibrated sphygmomanometers and stethoscopes was offered to the examinee, who, after selecting one of them, took the BP in front of two observers who were trained to follow the AHA guidelines.2 Immediately after the examinee determined the BP, one of the observers in the anteroom took the BP twice with the same equipment, and the average of the two readings was taken into account for correlation of the results. These observers were previously trained and evaluated on the AHA recommendations by a certified nephrologist to ensure unified criteria. Afterwards, the examinees answered a 10-point questionnaire about the basic standards of the AHA recommendations (Table).
For the practical test a passing score was given if all the steps were properly followed. This gives more support to the final analysis. On the other hand, for the theoretical test a passing score was obtained if 7 of 10 answers were correct. The highest variation in diastolic BP that was accepted between examinee and observer was ±4 mm Hg. Values above or below this range were considered incorrect whether plus or minus. The χ2 test was used for determination of differences between groups, and a value of P<.05 was considered statistically significant.
Results
The group of individuals evaluated was representative of the population of health-care workers in a large city and major hospital. Eighty-five (49.4%) of the examinees were men. Individuals between ages 20 and 65 years were evaluated, representing all age groups, with no difference in sex or experience.
Practical Test
All of the groups were notably inaccurate in the practical test. Only 3% of the general practitioners and 2% of the nurses obtained reliable results (P=NS in any group) (Fig 1). Arm and cuff positions were inadequate in 73%. Only 3% used the stethoscope bell.
Blood Pressure
Sixty-three percent of examinees were out of range in their readings of systolic BP (46% incorrect positive, 54% incorrect negative) and 53% in diastolic BP (40% incorrect positive, 60% incorrect negative). The nurses had the highest out-of-range values in both BP readings (P<.03 versus surgical specialists).
Theoretical Test
The clinical specialists obtained the best results in the theoretical test compared with the other groups, with 60% correct answers (P<.05) (Fig 2). The nurses showed the lowest results, with only 10% correct answers (P<.05 versus the general practitioners and clinical specialists). Regarding the systolic palpable pressure (radial pulse), 74% of the examinees were aware of its importance, but only 19% knew the reason for its usefulness and only 14% took it during the practical test (P<.00001 between theory and practice). Although 68% considered the mercury sphygmomanometer to be the most reliable measuring device, only 38% used it during the practical test (P<.0001 between theory and practice). Thirty-nine percent answered that the BP should be measured in both arms, and 56% believed it should be taken in the standing, supine, and sitting positions. Twenty-one percent and 27% of the examinees did not know which Korotkoff sound determined the systolic and diastolic BPs. Forty-two percent were not aware of the effect of arm position, and 55% did not know what cuff size should be chosen.
In all the groups except for general practitioners, there was a significant difference between the results of the theoretical test and the systolic BP taken, as also between the theoretical test and the diastolic BP taken by surgical specialists and nurses (P<.001).
Discussion
The main finding of this study showed that 60% of physicians and nurses working in a major hospital were taking BP inaccurately. This is not surprising if one considers the lack of training and literature available on the recommended techniques for taking BP, in addition to the arbitrary way in which health-care workers modify the technique and their lack of awareness of a disorder that affects more than 20% of adults and is a major public health problem.3 4 5 6 7 8
The individuals evaluated in this study should have had very good academic and technical backgrounds, considering the positions they held in a major hospital, but the theory does not match the practical results. Although the clinical specialists had a broader theoretical knowledge of BP technique compared with the rest of the health-care workers, their practical results were disappointing (P<.05) (Figs 1 and 2). The same situation occurred with the nurses, who showed poor results in both theory and practice, which is disturbing, considering that they are normally in charge of BP measurement. In addition, doctors usually rely on them for the purpose of BP follow-up. The same discrepancy between theory and practice was observed for the surgical specialists (Figs 1 and 2).
With regard to the methods used in this study to observe and validate the BP measurements, and considering that the goal of this study was the evaluation of the whole process for taking BP and not exclusively the health-care worker interpretation of Korotkoff sounds, the Y-stethoscope was not used. We believe that the use of this type of stethoscope would be ideal in a study designed for examinees well trained in the AHA recommendations, which would guarantee that not only the stethoscope but also the sphygmomanometer was correctly positioned and also that examinees would follow the rest of the recommended steps. Also, with the Y-stethoscope method the errors of the examinee would have altered the readings of the observer.
The examinees measured BP only once because despite the AHA recommendations this is the routine in daily clinical practice. Unknown observer/subject interactions (white coat, male/female) become unavoidable and unmeasurable variables in this type of study. Other remarkable findings in this investigation included the inadequate use of the sphygmomanometers, the erratic position of the stethoscope, the lack of knowledge of the basic principles of BP measurement, and the rounding off of the last digit of the BP reading to 0 or 5. The results also showed that the second BP readings (taken by the observers) were both higher and lower (almost 50% higher and 50% lower in systolic and diastolic readings, respectively) compared with the BP measurements taken by the examinees. Thus, a systematic lower BP effect from observer measurements cannot be inferred.
It is accepted that many clinical therapies in the management of hypertensive patients, that is, nonpharmacological, only reduce by a very few millimeters of mercury the systolic and diastolic BP values; for this reason, the results obtained in this study show the importance of taking BP accurately. How, then, would a health-care worker detect a change in BP as small as 1 or 2 mm Hg in BP, if the readings he or she takes are not reliable or the last digit is rounded off to 0 or 5?
Many symposia are held every year on the new developments, therapeutics, and diagnosis of hypertension, but the technique of BP measurement rarely receives the same consideration. The same situation is observed in medical schools.
In conclusion, this study shows that the health-care workers evaluated measured BP in an inadequate, incorrect, and inaccurate way independent of their specialty, sex, age, or experience. This conclusion warrants the implementation of procedures to improve the technique health-care workers use to take BP, starting with the training years and continuing during their clinical practice and followed by a continuing education program. It would also be of interest to carry out a repeat study after the health-care workers have received additional instruction on BP measurement.
| 1. Which do you think is the most appropriate manometer? |
| a. Mercury |
| b. Aneroid |
| c. Electronic or digital |
| 2. How often should the manometer be calibrated? |
| a. Every month |
| b. Every 6 months |
| c. Never |
| d. Whenever it fails |
| 3. How many times should blood pressure be measured on the first visit? |
| a. 1 |
| b. 2 |
| c. 3 |
| d. Any desired number of times |
| 4. What arm should be used to take blood pressure (not injured patients)? |
| a. Right |
| b. Left |
| c. Both |
| d. Either arm |
| 5. In what position should blood pressure be taken? (mark all that apply) |
| a. Standing |
| b. Supine |
| c. Sitting |
| 6. What determines systolic blood pressure? |
| a. The first sound heard |
| b. Change of intensity |
| c. High-pitched sound |
| 7. What determines diastolic blood pressure? |
| a. The last audible sound |
| b. Change of intensity |
| c. Low-pitched sound |
| 8. If a standard adult cuff (12-cm) is used in a very obese adult patient, you would expect the blood pressure results to be: |
| a. Falsely high |
| b. Falsely low |
| c. True |
| 9. The main reason why the radial pulse (systolic palpable pressure) should be measured is (mark all that apply): |
| a. To avoid the auscultatory gap |
| b. It is the best indication of systolic blood pressure |
| c. It avoids disturbing the patient more than necessary, due to the inflation of the cuff bladder |
| d. It is the best indication of diastolic blood pressure |
| 10. Regarding arm position, which is correct? |
| a. If the arm is raised, blood pressure increases |
| b. If the arm is lowered, blood pressure decreases |
| c. If the arm is raised, blood pressure decreases |
| d. The arm position does not affect blood pressure readings |
References
1.
1. Allman RM. Basic evaluation of older patients with hypertension. Clin Geriatr Med. 1989;5:717-730.
2.
Frohlich ED, Grim C, Labarthe DR, Maxwell MH, Perloff D, Weidman WH. Recommendations for human blood pressure determinations by sphygmomanometers: report of a special task force appointed by the Steering Committee, American Heart Association. Circulation. 1988;77:501A-514A.
3.
Bulletin. International Society of Hypertension, special edition, June 1993.
4.
Ljungvall P, Thulin T. Hand-free stethoscope-method and instrument for more reliable blood pressure measurement. Ann Intern Med. 1991;230:213-217.
5.
Canner PL, Borhani NO, Oberman A, Cutler J, Prineas RJ, Langford H, Hooper FJ. The Hypertension Prevention Trial: assessment of the quality of blood pressure measurement. Am J Epidemiol. 1991;134:379-392.
6.
Norman E, Gadeleta D, Griffin C. An evaluation of three blood pressure methods in stabilized acute trauma population. Nurses. 1991;40:86-89.
7.
Sprafka JM, Strickland D, Gómez-Marín M, Prineas RJ. The effect of cuff size on blood pressure measurements in adults. Epidemiology. 1991;2:214-217.
8.
Atkins N, Mee F, O’Malley K, O’Brien E. The relative accuracy of simultaneous same arm, simultaneous opposite arm and sequential same arm measurements in the validations of automated blood pressure measuring devices. J Hum Hypertens. 1990;4:647-649.
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Copyright
© 1995.
History
Received: 18 June 1995
Revision received: 16 September 1995
Accepted: 3 October 1995
Published online: 1 December 1995
Published in print: December 1995
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