Blood Pressure Lab
Introduction:
Blood pressure is an important physiological indicator of the state of a person’s cardiovascular health. The value of a person’s blood pressure reflects the combined work of cardiac output and total peripheral resistance. For example, if an individual has a high blood pressure, it means they are putting an increased strain on the arteries and on the heart. A heart under strain in turn increases the chance of a cardiovascular event or disease. Blood pressure is composed of two values, the systolic, or contraction value, and the diastolic, or relaxation value. Systolic blood pressure is susceptible to change, while diastolic blood pressure remains relatively stable despite rest or exercise.
Blood pressure responds differently to different states of being- rest vs. dynamic exercise, for example. Blood pressure is important at rest because it can reveal a person’s blood pressure category whether that be normal, pre-hypertensive, stage one or stage two. Refer to figure 1 below for the values associated with these categories. If an individual has high resting blood pressure, or hypertension, it may increase their risk for cardiovascular disease, and if it is too high (140/90), it may be unsafe for them to exercise. Resting BP is also important because it helps establish baseline values to develop an exercise prescription and compare pre- and post- training values.
Category Systolic Diastolic
Normal <120 and <80
Pre-hypertensive 120-139 or 80-89
HIGH
Stage 1 140-159 or 90-99
Stage 2 160+ or 100+
Figure 1*
During exercise, BP is very important to make sure that an individual is not exercising at unsafe levels. While it is normal for systolic blood pressure to increase due to the increased cardiac output that accompanies the increased rate of work, too high of levels may be dangerous. For instance, if the systolic value is >200 or diastolic value is >110, the exercise session should be stopped. Diastolic blood pressure typically remains unchanged or only slightly increases during exercise in response to an increased workload. Certain lifestyle changes may actually increase blood pressure values, such as smoking, caffeine, or sodium, while an increased fitness level may actually lower it.
The purpose of this lab is to gain a proficiency, or at least strong ability in taking and reading indirect blood pressure both during rest and during dynamic exercise. The lab will also allow for changes in heart rate and blood pressure to be observed during dynamic exercise. The blood pressure will be taken using a sphygmomanometer and a stethoscope, and the the Ebbeling Submaximal treadmill test will be utilized for dynamic exercise
Procedure:
Resting Blood Pressure:
Blood pressure is assessed using a stethoscope and a sphygmomanometer, which includes an inflatable arm cuff connected to a mercury gauge and a bulb with an air control valve to pump up the arm cuff. The correct cuff size must be determined for the participant, as an incorrect or ill-fitting cuff may skew results. The bladder should encircle at least 2/3 or the arm. The arm cuff is places around the brachial artery of the upper right arm, and the patients arm should be appropriately supported by the person assessing blood pressure. The stethoscope is placed over the brachial artery in the ante-cubital space towards the inside of the arm- just below the cuff. With the valve in one hand, grip the controller knob of the air valve with the thumb and index finger. The stethoscope should be held in the other hand.
Make sure that the subject is keeps their arm relaxed as their blood pressure is taken. Make sure the mercury column is in a clear line of sight and that the patients arm is supported at heart level. With the air valve in a tightened, or closed, position, and with all of the air completely emptied from the cuff, hold the bulb and pump air into the cuff so that the pressure on the mercury gauge reaches at least 180 mmHg. Once the gauge reaches 180 mmHg, slowly loosen the air valve to slowly let air out of the cuff with your thumb and index finger, at about 2-4 mmHg per second, until the force developed by the heart during systole is great enough to force blood past the cuff. Listen through the stethoscope for the first thumping sound of the heart- the systolic, contraction phase. The number at which this occurs is the systolic pressure, or the top number reported in blood pressure. Then, when the thumping sound dies out and becomes muffled, the last disappearing muffled sound that is heard is the bottom number of blood pressure, the diastolic, relaxation phase of the heart contraction. After the blood pressure has been read, release the rest of the air from the cuff, remove it, and record the blood pressure.
Ebbeling Submaximal Treadmill Test:
Prior to beginning the Ebbeling Submaximal Treadmill Test, walking speed for the for the test was individually determined by the individual on the basis of size, gender, and fitness level. Additionally, the participants estimated their age-predicted maximal heart rate by the calculation (220-age). From this number, they then calculated 50%, 70%, ad 85% of their maximal heart rate. Before beginning the test, the participant had to put on a heart rate monitor chest strap that was easily worn during the test. The monitor sent data to a watch that was observed during the test. A resting heart rate was recorded. Lastly, a resting blood pressure was taken, using the above-mentioned methods.
After calculations were made and the equipment was in place, the test can begin. The participant stepped onto the treadmill and began warming up at the predetermined speed for 4 minutes at a 0% grade in order to bring their heart rate up to between 50 and 70%. This was stage one of exercise. A heart rate for the participant was recorded at minutes 1, 3, and 4. At minute 4, a blood pressure reading was also recorded (the group member was advised approximately 1.5 minutes before the reading was to take place in order that they could get in position. The blood pressure was taken by having a member of the participant group attach the blood pressure cuff to the participant’s arm, using a stool if necessary, and use the same methods as mentioned above to record the blood pressure. The learning stethoscope was used for another group member to listen in, and aid in accuracy. The participant had to extend their arm at heart level and allow it to be supported by the group member, and leave it as relaxed as possible. After a reading was taken, the cuff was removed and the participant continued walking.
After the fourth minute, stage two of the exercise test was entered, and the group raised the treadmill grade of the participant to 5%. The participant was to keep walking as they had been. A heart rate value was take at minute five, and eight, as well as another blood pressure reading at minute 8. After minute 8 was concluded, the treadmill was slowed to a stop and the grade reduced to 0%. In the Post exercise phase, another heart rate and blood pressure reading was taken at 60 seconds post exercise and 120 seconds post exercise. After these final readings, the test was concluded and the data entered into a group excel file.
Data:
Figure Two*
As illustrated in figure two and as expected, systolic blood pressure increased significantly due to dynamic exercise from 109 resting to 128 during the more strenuous phase of the exercise test, and returned to near normal after the dynamic exercise was stopped. While the final post exercise blood pressure was close to the initial, pre-exercise blood pressure, it had not yet fully resumed its resting state.
Figure three*
Again, as expected, diastolic blood pressure experienced little change in response to dynamic exercise, only changing about 4 mmHg in average over the entirety of the test from about 62 mmHg to 63 during exercise, back down to about 59 during post exercise.
Conclusion/Discussion:
This lab definitely allowed for students to practice taking and reading blood pressure and observing its fluctuations, as each Ebbeling submaximal treadmill test required 5 blood pressure readings. The graphs created from the data also helped for trends in blood pressure changes to be easily seen and recognized. The lab also allowed for students to understand the importance of blood pressure as a physiological indicator of health and fitness and the values of blood pressure that indicate something may be wrong with the body (pre-hypertension, hypertension, etc.) This lab also allowed us to see how blood pressure changes with changes in the state of the body, whether it is at rest or undergoing work.
For healthy young individuals, the average blood pressures recorded from the experiment were normal in both the resting state and the exercise state. The average resting BP observed (~110 mmHg) was under the normal recommendations, and the exercising BP was well under 200/110, indicating safe exercise. Systolic BP rose during exercise as expected due to the increased cardiac output that accompanies the increased rate of work, and diastolic BP remained relatively the same.
As an intended physical therapist, assessing BP will be an important part of my job. Assessing resting blood pressure will be important in making sure it is safe for a client to do a certain exercise and will help me establish baseline values for developing exercise prescription and comparing pre- and post- values for clients. Measuring a client’s dynamic BP is important also because it will allow me to monitor the safety of a client who is exercising and may be susceptible to reaching unsafe BP values. It would be a mistake for a PT to prescribe something outside of the capacity a client can do, and why blood pressure plays such a critical role in PT.
In conclusion, this lab allowed for blood pressure to be explored in many aspects: We were able to practice taking BP at rest and during dynamic exercise, learn the procedure of the Ebbeling Submaximal treadmill test, and also observe changes in BP as a result of dynamic exercise. The lab allowed us to learn many different applications of BP and fully realize the significance it holds.
Question Section:
When manually assessing resting and exercise blood pressure what are some potential sources of error during blood pressure assessment? What are some strategies you can use to avoid these sources of error? (10 points)
One common source of error is the participant using their own muscles to support their arm at heart level, and therefore skewing the results of the BP reading. To avoid this, the BP taker must fully support the arm of the participant, ensuring that the participant will not have to flex any muscles in order to support their own arm.
Another common error is placing the stethoscope in the wrong region of the arm and therefore not being able to read the BP at all, because nothing was heard. To fix this, the BP reader can practice finding the brachial artery in the ante cubital space on the patient before attempting to take the BP.
Lastly, some people may skew the BP reading by relying on watching the pumping of the mercury gauge. This can be avoided by focusing on taking the recording based only on the sounds heard through the stethoscope rather than the visual pumping of the mercury gauge.
What was your seated resting blood pressure? Were your systolic blood pressure and diastolic blood pressure within the normal range, as defined in the ACSM Guidelines for Exercise Evaluation and Prescription book? If they were not in the normal range, what range did they fall into?
Provide at least one reason why your seated systolic and/or diastolic blood pressure fell within a normal, prehypertensive or hypertensive range. (10 points)
My seated resting blood pressure was 108/62, which is in the normal range as defined by the ACSM guidelines. My resting blood pressure was likely in the normal range because I am young, healthy, and relatively fit (I go to the gym 3+ times a week).
During an aerobic exercise session why is it important to monitor an individual’s blood pressure before, during and after the exercise session? (10 points)
It is important to measure a person’s blood pressure prior to exercise because you can observe if the BP values are too high to exercise. Starting exercise with a blood pressure in an at-risk state may increase the odds of a cardiovascular event, and therefore is unsafe without consulting a physician. It is also important to measure BP during exercise to ensure that the individual is not exercising at unsafe levels (200+/110+). Finally, it is important to measure BP post exercise to ensure that their BP is returning to an appropriate resting state. If a person’s BP remains elevated, it may be indicative of a cardiovascular event or that something is not quite right with the individual, and that they may need to consult a physician.
