1. Blood Pressure
Telehealth (2010), Blood Pressure monitor [picture]. Retrieved from

2. Summary Clinical Use History Specifications Principles of Operation
Block Diagram
Commercial Examples
Preventive Maintenance
Common Problems
Test Procedures

3. Heart’s Anatomy
Wikipedia. “Heart.” Wikipedia, p Retrieved from:

4. Circulatory Pressures
Yaddah (2006), View from the front [image]. Retrieved from

5. Häggström, Mikael. "Medical gallery of Mikael Häggström 2014"
Häggström, Mikael. "Medical gallery of Mikael Häggström 2014". Wikiversity Journal of Medicine 1 (2). DOI: /wjm/ ISSN (All used images are in public domain.) [Public domain], via Wikimedia Commons

6. Mechanisms for Pressure Control
Mikael Häggström and Madhero88 (Adapted from File:Kidney copy.png by Madhero88) [Public domain], via Wikimedia Commons
Kidney changes the amount of urine that is produced

7. Hypotension Causes Symptoms Results Dehydration Bleeding Inflammations
Drug’s Allergy
Dizziness
Light headedness
Shortness of breath Chest pain
Coma
Organs failures

8. Hypertension Causes Symptoms Results Increased salt intake Obesity
Alcohol
Stress
Lack of exercise
Headache
Blurry vision
Chest Pain
Frequent urination at night
Stroke
Congestive heart failure
Kidney failure
Heart attack
Heart rhythm problems
Aneurysm - dilation
An aneurysm (or aneurism ) is a localized, blood-filled dilation (balloon-like bulge) of a blood vessel caused by disease or weakening of the vessel wall.

9. History 1733 Reverend Stephen Hales Invasive Catheterisation Method
1905 Korotkoff
The Auscultatory Method
1970s Digital blood pressure monitor
Invasive Catheterisation Method
In 1733, Reverend Stephen Hales inserted a long glass tube upright into an incision in a horse's artery. The pumping action of the heart generated a pressure force, causing the blood level to rise in the tube. These early surgical procedures were dangerous for patients, due to the risk of infection and excessive blood loss. Even today, invasive catheterisation procedures are seldom used solely for blood pressure measurement. Instead, non-invasive (i.e. non-surgical) methods sacrifice a degree of accuracy for patient safety, comfort, and convenience.
The Auscultatory Method
In 1905, Korotkoff described the auscultatory sounds which became the foundation for the auscultatory technique. This is the most common method of blood pressure measurement today.
An air-filled cuff is wrapped around the patient's upper arm. The cuff is inflated to occlude the brachial artery. As the cuff is allowed to deflate, a stethoscope is placed over the patient's brachial artery (distal to the cuff). The clinician uses the stethoscope to listen for the Korotkoff sounds as the cuff deflates. The beginning of Phase I is systolic pressure. There is some debate as to whether Phase IV, Phase V, or a combination of the two best represents diastolic pressure. This situation is complicated by the fact that some patients may not have audible Phase IV sounds, and in others Phase V may be difficult to determine.
The auscultatory technique is based on the ability of the human ear to detect and distinguish sounds. This is a great advantage since it allows the clinician to determine the quality of each measurement. However, inherent in this is the possibility for measurement error due to differences in hearing acuity from clinician to clinician. Unqualified or inexperienced personnel may be more susceptible to outside noise, other interference, or inconsistent assessment of Korotkoff sounds. In an attempt to increase reproducibility, some automated devices have replaced the human ear with a microphone.
The Automated Auscultatory Method
These devices apply sound-based algorithms to estimate SBP and DBP. By using a microphone, these devices lack validation ability. In addition to noise-artifact sensitivity, these sound-dependent algorithms may not adequately compensate for patient conditions such as hypotension (i.e. low blood pressure), where the Korotkoff sounds may be muted. To make automated measurement more reliable, oscillometric devices were created.
The Oscillometric Method
The term "oscillometric" refers to any measurement of the oscillations caused by the arterial pressure pulse. These oscillations are the direct results of the coupling of the occlusive cuff to the artery. This method allowed blood pressure measurement of critical care and intensive care (ICU) patients with muted Korotkoff sounds. These devices do not use microphones. Therefore, cuff placement and external noise are not significant problems. These devices are sensitive to patient movement and do not allow measurement validation. Following is the arterial waveform display by using the oscillometric method:
Unlike auscultatory techniques, which measure systolic and diastolic but estimate mean arterial pressure, oscillometric devices measure the mean but estimate systolic and diastolic. An air-filled cuff is wrapped around the patient's upper arm. The cuff is inflated to occlude the brachial artery. As the cuff is allowed to deflate, pressure data is recorded by the device. Over time, the pressure data looks like a waveform (see below). The point of maximum amplitude is considered mean arterial pressure. Systolic and diastolic are estimated from mean arterial pressure (MAP). Therefore, an erroneous determination of MAP may produce inaccurate values for systolic and diastolic.
Pulse Dynamics, the patented technology by Pulse Metric, is a variant of the oscillometric method. It combines the reliability of oscillometrics with the validation capability of the manual auscultatory method.

10. Clinical Use Primary diagnostic and monitoring tool Range:
120 mmHg systolic
80 mmHg diastolic
Mariana Ruiz Villarreal (LadyofHats) (Own work) [Public domain], via Wikimedia Commons. Retrieved from

11. Specifications Input: Pressure (0 mmHg - 300 mmHg)
Output Electronically (display)
Systolic, mmHg
Diastolic, mmHg
Wikipedia, “Blood Pressure.” Wikipedia, p Date retrieved: September, 16, Retrieved from:

12. Principles of Operation Acoustic Method (Auscultatory)
Heart Sounds
Sound
Origin
1st sound
Closure of mitral and tricuspid (input) valves
2nd sound
Closure of aortic and pulmonary (output) valves
3rd sound
Rapid ventricular filling in early diastole
4th sound
Ventricular filling due to atrial contraction

13. Principles of Operation
Acoustic Method
ProfBondi (Own work) [CC BY-SA 3.0 ( via Wikimedia Commons

14. Principles of Operation
Acoustic Method
Pressure Sensors: Mercury
Robert Malkin (2006), Medical Instrumentation in the Developing World [image]. Retrieved from library.ewh.org

15. Principles of Operation
Acoustic Method
Pressure Sensors: Aneroid (Bourdon Gauge)
DStaiger (Own work) [CC BY-SA 3.0 ( via Wikimedia Commons. Retrieved from

16. Principles of Operation
Oscillometric Method
Cromwell, L. et. al. “Blood Pressure Measurement.” From the publication Biomedical instrumentation and Measurements. Prentice Hall (1973), pgs

17. Principles of Operation
Oscillometric Method
Cooper, Justin and Alex Dahinten for Engineering World Health. “Blood Pressure Monitor (Manual) Preventative Maintenance.” From the publication Medical Equipment Troubleshooting Flowchart Handbook. Durham, NC: Engineering World Health (2013).

18. Principles of Operation
Oscillometric Method
Julo (2005), Blood Pressure [photograph]. Retrieved from

19. Principles of Operation
Oscillometric Method
Pressure Sensors: Piezoelectric
Tizeff (Template:Ownnn) [GFDL ( or CC BY-SA 3.0 ( via Wikimedia Commons

20. Principles of Operation
Oscillometric Method
Pressure Sensors: Piezoelectric
Medvedev (Own work) [CC BY-SA 3.0 ( via Wikimedia Commons

21. Blood Pressure Setup
Cromwell, L. et. al. “Blood Pressure Measurement.” From the publication Biomedical instrumentation and Measurements. Prentice Hall (1973), pgs

22. Ultrasonic Technique
National Heart Lung and Blood Insitute (NIH) (National Heart Lung and Blood Insitute (NIH)) [Public domain], via Wikimedia Commons. Retrieved from

23. Invasive Blood Pressure
Common in surgery and intensive care units
A completely different approach to measuring blood pressure is to invasively introduce a catheter
into an artery. This is most common in surgery and intensive care units. The blood pressure
device is connected to the catheter via a rigid wall plastic tube filled with a saline solution. The
tube is connected to a transducer, which may be connected to bag of saline or “flush.” Figure
2.7.3 illustrates the set up. The transducer is hung at the level of the heart. The output from
the transducer is amplified and displayed as numbers, waveform or both. Since the skin has
been breached the patients first line of defense for both infection and electrical shock have been
bypassed. Extreme care must be taken to assure the safety of the
patient.
For the invasive method, a hollow tube (cannula) is inserted in the artery. The cannula is connected to the pressure transducer via a thin tube called a catheter. There are two system arrangements – the infusion system and the constant flush system.
The infusion system is shown in Slide 20: There must be no air in the tubing; it is filled with a saline solution. This system is prone to plugging by clotting blood. Air must be bled out of the lines and only a non-compressible liquid used.
Slide 21 shows the constant flush infusion system that is used for longer term monitoring. Pressure is applied to the bag to force the liquid into the system. The valve is set to allow a small flow such as 3ml/hr is used. The heparin (a drug that prevents blood clotting) is added to the saline to help keep the catheter clear of clots. (Mention anesthetic and blood thinner used by leaches.) The fast flush device is used to force the liquid into the system to fill the transducer dome. The fast flush is also used to clear clots.
Robert Malkin (2006), Medical Instrumentation in the Developing World [image]. Retrieved from library.ewh.org

24. Invasive Blood Pressure
Applications:
Arterial
Central venous
Pulmonary arterial
Left atrial
Right atrial
Femoral arterial
Umbilical venous
Umbilical arterial
Intracranial pressures
A completely different approach to measuring blood pressure is to invasively introduce a catheter
into an artery. This is most common in surgery and intensive care units. The blood pressure
device is connected to the catheter via a rigid wall plastic tube filled with a saline solution. The
tube is connected to a transducer, which may be connected to bag of saline or “flush.” Figure
2.7.3 illustrates the set up. The transducer is hung at the level of the heart. The output from
the transducer is amplified and displayed as numbers, waveform or both. Since the skin has
been breached the patients first line of defense for both infection and electrical shock have been
bypassed. Extreme care must be taken to assure the safety of the
patient.
For the invasive method, a hollow tube (cannula) is inserted in the artery. The cannula is connected to the pressure transducer via a thin tube called a catheter. There are two system arrangements – the infusion system and the constant flush system.
The infusion system is shown in Slide 20: There must be no air in the tubing; it is filled with a saline solution. This system is prone to plugging by clotting blood. Air must be bled out of the lines and only a non-compressible liquid used.
Slide 21 shows the constant flush infusion system that is used for longer term monitoring. Pressure is applied to the bag to force the liquid into the system. The valve is set to allow a small flow such as 3ml/hr is used. The heparin (a drug that prevents blood clotting) is added to the saline to help keep the catheter clear of clots. (Mention anesthetic and blood thinner used by leaches.) The fast flush device is used to force the liquid into the system to fill the transducer dome. The fast flush is also used to clear clots.

25. Continuous Non-invasive
Arterial Pressure
A completely different approach to measuring blood pressure is to invasively introduce a catheter
into an artery. This is most common in surgery and intensive care units. The blood pressure
device is connected to the catheter via a rigid wall plastic tube filled with a saline solution. The
tube is connected to a transducer, which may be connected to bag of saline or “flush.” Figure
2.7.3 illustrates the set up. The transducer is hung at the level of the heart. The output from
the transducer is amplified and displayed as numbers, waveform or both. Since the skin has
been breached the patients first line of defense for both infection and electrical shock have been
bypassed. Extreme care must be taken to assure the safety of the
patient.
For the invasive method, a hollow tube (cannula) is inserted in the artery. The cannula is connected to the pressure transducer via a thin tube called a catheter. There are two system arrangements – the infusion system and the constant flush system.
The infusion system is shown in Slide 20: There must be no air in the tubing; it is filled with a saline solution. This system is prone to plugging by clotting blood. Air must be bled out of the lines and only a non-compressible liquid used.
Slide 21 shows the constant flush infusion system that is used for longer term monitoring. Pressure is applied to the bag to force the liquid into the system. The valve is set to allow a small flow such as 3ml/hr is used. The heparin (a drug that prevents blood clotting) is added to the saline to help keep the catheter clear of clots. (Mention anesthetic and blood thinner used by leaches.) The fast flush device is used to force the liquid into the system to fill the transducer dome. The fast flush is also used to clear clots.
Cromwell, L. et. al. “Blood Pressure Measurement.” From the publication Biomedical instrumentation and Measurements. Prentice Hall (1973), pgs

26. Commercial Examples
Wikipedia, “Blood Pressure.” Wikipedia, p Date retrieved: September, 16, Retrieved from:

27. Most commonly found in the developing world
Wikipedia, “Blood Pressure.” Wikipedia, p Date retrieved: September, 16, Retrieved from:

28. Patient’s Safety
No main safety issues have been reported for non-invasive blood manual pressure devices
NIBP machines have a safety valve (pressostat) which opens whenever the pressure exceeds the maximum limit

29. Patient’s Safety Invasive
Thrombosis
Infection
Bleeding
Requires special electrical protection since the skin barrier has been breached
A completely different approach to measuring blood pressure is to invasively introduce a catheter
into an artery. This is most common in surgery and intensive care units. The blood pressure
device is connected to the catheter via a rigid wall plastic tube filled with a saline solution. The
tube is connected to a transducer, which may be connected to bag of saline or “flush.” Figure
2.7.3 illustrates the set up. The transducer is hung at the level of the heart. The output from
the transducer is amplified and displayed as numbers, waveform or both. Since the skin has
been breached the patients first line of defense for both infection and electrical shock have been
bypassed. Extreme care must be taken to assure the safety of the
patient.

30. Preventive Maintenance
Requires calibration every 6 months normally
Wikipedia, “Blood Pressure.” Wikipedia, p Date retrieved: September, 16, Retrieved from:

31. Preventive Maintenance
Old mercury manometers may oxide forming a black powder
Remove and filter the mercury through filter paper
reservoir
Mercury is toxic DO NOT touch or breath it!
Malkin, R. “Blood Pressure Machines,” From the publication: Medical Instruments in the Developing World. Engineering World Health, 2006.

32. Preventive Maintenance
Calibration
If the pressure is consistently too high or too low, you will need to adjust the zero by removing or adding mercury
Wikipedia, “Blood Pressure.” Wikipedia, p Date retrieved: September, 16, Retrieved from:

33. Common Problems Leaks in the tubing are common
Find it by rubbing soapy water over the tubing and looking for bubbles
One can repair it with epoxy or silastic

34. Common Problems User error The cuff must be at the level of the heart
The manometer must read zero before the cuff is inflated

35. Test Procedures Sphygmomanometer Check the device valve
When inflated with the valve closed, the pressure should not drop appreciably in ten seconds
When the valve is open, the pressure should drop slowly and linearly

36. Test Procedures Calibration with a standard device:
Measure your own blood pressure five times
Measure your with another calibrated device five times. The two systems should match to within 3 mmHg

37. Test Procedures NIBP Machines
Calibration with a column of water in a tube up to a height of 271 cm, (200 mmHg)
Check several pressure levels:
mmHg
cm H20
200
271
100
136 50 68
Robert Malkin (2006), Medical Instrumentation in the Developing World [image]. Retrieved from library.ewh.org

38. NIPB with Alarm Setting
© 2015 Medisave UK Ltd. Retrieved from

39. Test Procedures NIBP Machines Check the heart rate alarms:
Lower than your own heart rate
(upper rate alarm)
Higher than your own heart rate
(lower rate alarm).
Check battery (if present) charging circuit

40. Questions ?