A History of Blood Pressure
- V. A. Cyr
- Aug 21, 2024
- 16 min read
We have all gone to the doctor and had to have our blood pressure taken. How does it work, and what do the numbers mean? Why does the cuff have to squeeze so tight? What does the word “sphygmomanometer” mean? This post will examine the backbone of the vital signs: Blood Pressure! Along with the other vitals measured during an assessment (Heart Rate, Respiration, Temperature, and Pulse Oximetry), it gives a good idea of how a patient is doing physically. We will dissect where it originated and how the treatments have evolved.
Definition
Blood pressure measures how much pressure the blood is being pushed into the circulation by the heart. It measures two numbers: the systolic and the diastolic. The average blood pressure for an adult is aimed at 120 over 80 millimetres of mercury (120/80 mmHg). The term “tension” comes from the Latin word tensio meaning “to tighten, constrict or spasm" (Merriam-Webster, 2024). “Hyper” and “hypo” mean high and low, respectively. Therefore, hypertension is high tension, and hypotension is low tension (or blood pressure). These will be examined more thoroughly later in the post.
Types of Measurement
Manual Blood Pressure
Every nurse learns to manually take blood pressure with a stethoscope and sphygmomanometer (“blood pressure cuff”). Manual blood pressure is examined in the Auscultation post. There are different parts to a blood pressure cuff, including the sphygmomanometer (dial), the cuff, the hoses, the gasbag (baloon that is pumped to fill the cuff with air), and the thimble (to control the air leaving the gasbag).
Here is an image of a manual sphygmomanometer (Littman, n.d.).
This image of a manual sphygmomanometer may be seen on the walls or mobile around medical clinics (Baxter, n.d.).
Electronic Blood Pressure
Blood pressure machines are now more commonly used in healthcare settings and patients’ homes. These monitors are easier to use and do not require the nurse to auscultate or manually inflate the cuff. Research has shown that automated blood pressure readings are more accurate, as manual blood pressure readings tend to be higher (Mirdamadi & Etebari, 2017). Having a machine do this also saves time and allows the nurses to do other tasks while the monitor automatically verifies the patient’s vitals.
Patients can use an automatic blood pressure machine like this one at home (Med Supplies, n.d.).
This image is a version of a modern vital sign machine seen in a hospital (Baxter, n.d.).
Like manual machines, these can be attached to walls or on a mobile stand. These modern machines can measure and store a patient’s vitals (i.e., blood pressure, pulse, pulse oximetry, and temperature).
Location of Blood Pressure Measurement
Normally, the blood pressure (manual or automatic) is taken on the upper arm (preferably the left). It is best to achieve one measurement on both arms and acreage them to get a more accurate blood pressure. The nurse must ensure that an appropriately sized cuff is used for the circumference of the patient’s arm (i.e., pediatric, small, regular, large, or extra-large). A cuff that is too small can give a wrongly high systolic blood pressure, while one that is too large can mistakenly give a low blood pressure reading. The positioning must be correct for the body part they are measuring (e.g., upper arm, forearm, lower leg). An arrow on the cuff indicates where to place it on the artery (e.g., brachial) that is being measured. The change of location is done when the cuffs are the wrong size for the patient’s arm. Different locations on the body also have different blood pressures. For example, the systolic is higher, and the diastolic is lower in the legs than in the arms.
Here is an image showing the placement of the blood pressure cuff in different locations on the body (wrist, ankle, upper arm, and thigh) (Arab, 2018).
Arterial Blood Presure Monitoring
This invasive form of blood pressure measurement involves inserting a cannula (catheter) through a peripheral (brachial) artery (Nguyen & Bora, 2023). This method is only used in critically ill patients or during some surgical interventions. This is similar to inserting an intravenous (IV) catheter, but this is inserted into an artery instead. They use special intravenous tubing to measure the artery’s pressure, including a transducer attached to a cable.
Here is an image of a typical intra-arterial blood pressure monitoring system (Jones & Pratt, 2009).
Physiological Factors Affecting Blood Pressure
Heart Rate
The heart rate, or pulse, is the number of times the heart beats in one minute (beats per minute). A healthy adult’s range is between 60 and 100 bpm, but elite athletes can have a resting heart rate of 40 bpm. To keep the body in homeostasis (balance), the heart rate will increase and decrease depending on demand with vasodilation and vasoconstriction. The blood pressure can also help with homeostasis similarly. For example, if someone begins to exercise, their body needs more oxygen to function, and heart rate and respiration will increase to compensate.
Cardiac Output
Cardiac Output = Stroke Volume x Heart Rate
Cardiac output is the amount of blood pumped by the heart in one minute, measured in litres (L). At rest, regular adults should pump 5 to 6 L of blood every minute (King & Lowery, 2023).
Stroke Volume
Stroke Volume = End-Diastolic Volume - End-Systolic Volume
Stroke volume is the amount of blood ejected from the heart’s left ventricle during each systolic contraction. The average stroke volume amount should be about 1 millilitre of blood for each kilogram that the person weighs (e.g., 70 mL for a 70 kg person). The measurement of stroke volume is the difference between the amount of blood in the ventricle before (end-diastolic volume) and after (end-systolic volume) contraction (Bruss & Raja, 2022).
Pulse Pressure
Pulse Pressure = Systolic Blood Pressure - Diastolic Blood Pressure
This is the difference between the systolic and diastolic numbers measured during blood pressure. For example, a blood pressure of 120/80 mmHg has a pulse pressure of 40 mmHg (120 - 80 = 40), which is considered a healthy pulse pressure. This can be affected by several factors, like decreased cardiac output or physical barriers to the heart pumping properly. A narrow pulse pressure (less than 40 mmHg) is seen in individuals who do a lot of cardiac (cardio) exercises (e.g., running) and those who have disorders like heart failure, aortic stenosis (hardening of the aorta), and cardiac tamponade (fluid buildup around the heart) (Homan et al., 2023). A widened pulse pressure (over 40 mmHg) can be seen in aortic regurgitation (leaky artery), iron deficiency anemia (reduced hemoglobin in the blood), and arteriosclerosis (thickening of the arteries) (Homan et al., 2023).
Mean Arterial Pressure (MAP)
Mean Arterial Pressure = Diastolic Blood Pressure + ⅓ Pulse Pressure
MAP is the average martial pressure throughout one cardiac cycle (systole and diastole) (DeMers & Wachs, 2023). MAP is influenced by factors such as cardiac output and vascular resistance. The organs need a MAP of at least 60 mmHg to function correctly. If the MAP is below 60 mmHg for an extended period, there could be ischemia (reduced blood supply and oxygen) and infarction (tissue death) in the organs. The body regulates MAP by controlling cardiac output (e.g., increasing blood pressure) and vascular resistance (e.g., vasodilation or increasing the size of the arteries and veins) (DeMers & Wachs, 2023).
Individual Factors Affecting Blood Pressure
Age
As a person ages naturally, their blood vessels become thicker and stiffer. This is why older adults have a higher risk of hypertension. A poor diet and lack of exercise can accelerate this effect. This will lead to a decreased lumen (hollow passage inside vessels) and increased resistance within the blood vessels, which causes hypertension. With the rise in obesity in children that is currently occurring, hypertension has been seen more and more (NHLBI, 2024). Usually, children have lower blood pressure than adults.
Sex
Men in middle age are more likely to have hypertension than their female counterparts. However, in the older adult category, females have a higher risk (NHLBI, 2024). There is also a risk of females having both hypertension (gestational hypertension) and hypotension during pregnancy.
Here is a chart demonstrating the average blood pressure in children, adolescents, and adults (Ramburger, 2022). The sex of the adults was specified in the different age groups as they had different average blood pressure levels.
Genetics
Family history of hypertension can be passed through generations. A patient can have a higher risk of developing a heart condition if they have a biological family member with that condition.
Ethnicity
Hypertension is more common in Black adults compared with other racial or ethnic groups. They tend to have higher average blood pressure measurements and get high blood pressure earlier in life (NHLBI, 2024). Also, some medications for hypertension may not work as well for Black people (NHLBI, 2024).
Lifestyle
Lifestyle choices can increase the risk of hypertension and cardiovascular disease (NHLBI, 2024). These include diet, exercise, socioeconomic situation, and vices. An unhealthy diet high in salt will lead to atherosclerosis (hardening and thickening of vessels) and possible blockages within the blood vessels (NHLBI, 2024). A lack of physical activity and a sedentary lifestyle can increase the risk of hypertension. Socioeconomic factors contributing to poor health include income, education level, home and work environment, poor sleep, and high-stress situations (NHLBI, 2024). Unhealthy habits (e.g., drinking alcohol, caffeine, smoking, using illicit drugs) can also increase the risk.
Comordbities
Comorbidities are conditions that a person has in addition to their primary diagnosis. Certain diseases and medications can increase a person’s chance of developing hypertension. Diseases include cancer (tumours), chronic kidney disease, metabolic syndrome (i.e., hyperglycemia, hypertriglyceridemia, and hypoalphalipoproteinemia), sleep apnea (periods of not breathing), and thyroid disorders (e.g., hypothyroidism) (NHLBI, 2024). Medications that can cause hypertension include antidepressants, decongestants, hormonal birth control pills, and non-steroidal anti-inflammatory drugs (e.g., aspirin, ibuprofen) (NHLBI, 2024).
Similarly, hypotension can also be caused by many disorders and medications. Some disorders include bleeding, dehydration (lack of water), diabetes (difficulty producing insulin), and heart conditions (e.g., arrhythmias) (NHLBI, 2022). Examples of drugs that cause hypotension are hypertension medications, antidepressants, and medications to treat Parkison’s disease (NHLBI, 2022).
Origins
There is mention of “hard pulse disease” (presumed to be hypertension) as early as 2600 BC (Ensunge, 1991). The first blood pressure measurement was done on horses and small animals by Englishman Stephen Hales in 1733. Hales was a natural philosopher and inventor who did many experiments with animals that led to the study of blood pressure (Lewis, 1994).
In 1840, Richard Bright discovered “Bright’s disease” (now known as chronic kidney failure) by finding renal hypertension in patients with proteinuria (protein in the urine) (Khan, 2006). In 1874, Frederick Akbar Mahomed, using a sphygmograph, proved that hypertension can be a cardiovascular disorder unrelated to the kidneys (O'Rourke, 1992). A sphygmograph was created by Karl von Vierordt in 1854 to measure the rise and fall of a person’s pulse (Lau, 2016). It works by compressing the radial pulse and, using a system of weights, moving up and down to draw the pulse on a piece of paper. This was used to approximate a person’s systolic blood pressure.
Here is a diagram of a sphygmograph (Welcome Library, 2018).
In 1881, an Austrian physician named Samuel Siegfried von Basch created the first non-invasive blood pressure measurement tool, the sphygmomanometer (Roguin, 2006). In 1896, Italian pediatrician Scipione Riva-Rocci further developed the tool into the mercury sphygmomanometer, which is more similar to today’s equipment (Roguin, 2006). However, these could only be used to measure the systolic blood pressure.
This is an image of a sphygmomanometer made by Riva-Rocci (Wood Library-Museum of Anesthesiology, 2024). The mercury would increase and decrease in the glass chamber to indicate the number.
Also, in 1896, Sir Thomas Clifford Allbutt called the disease of high arterial pressure hyperpiesis to distinguish it from Bright’s disease (Calvo-Vargas, 1996).
In 1905, Nickolai Korotkoff, a Russian military surgeon, described what sounds are heard upon auscultation to determine systolic and diastolic pressures (Campbell et al., 2023). These sounds are described in the Auscultation post.
Then, in 1911, Eberhard Frank coined the term hypertonie essentielle, meaning essential hypertension (see below) (Ensunge, 1991).
In the 1970s, Donal Nunn developed the automated “oscillometric” sphygmomanometer (Sharman et al., 2023). This machine made it easier to take serial blood pressure measurements and is the type of sphygmomanometer we still use today. Several manufacturers produce their models of machines, but the first commercial machine was called the Device for Indirect Non-invasive Automatic Mean Arterial Pressure or DINAMAP (Sharman et al., 2023). (Those who work in a hospital setting have all heard someone yelling for a DINAMAP!)
Here is a photo of a DINAMAP from 1978 (Wood Library-Museum of Anesthesiology, 2024). There have been many evolutions of this machine since then!
Uses in Medicine
Diagnosing and treating a cardiovascular disorder is essential to preserve a good quality of life. As the reasons for hyper- or hypotension differ, many different treatment methods exist. Usually, hypotension is treated based on the symptoms and underlying cause of the issue. Asymptomatic hypotension may not require any interventions. If a patient arrives with hypotension, they likely have a more prominent problem (e.g., significant bleeding), and the first treatment option for them is fluid replacement therapy (giving intravenous fluids). However, all hypertension should be monitored and treated accordingly with medications to lower the blood pressure. The following sections will discuss the differential diagnoses of both types of blood pressure disorders and the history of the treatments for hypertension.
Diagnosis of Hypotension
Hypotension means "low" (hypo) blood pressure (tension). This can be measured approximately at 90/60 mmHg or lower. There are various types of hypotension:
Benign hypotension is low blood pressure that is asymptomatic and does not indicate a disease process.
Orthostatic hypotension, or postural hypotension, is a drop in blood pressure during positional changes (e.g., laying down to standing up).
Postprandial hypotension is a decrease in blood pressure one to two hours after eating a large meal.
Neurally mediated hypotension is a drop in blood pressure after standing for long periods.
Hypotensive shock can occur from a combination of other types below (combined type). Shock is a life-threatening condition in which there is a lack of blood flow throughout the body. (It is not the same as someone "going into shock" after a traumatic experince).
Distributive shock occurs as a failure to maintain peripheral resistance in the blood vessels with maintained cardiac function attempting to compensate (Sharma et al., 2023). This occurs during anaphylaxis (life-threatening allergic reaction) and septic shock (organ failure due to sepsis or generalized infection).
Cardiogenic shock is a failure to achieve sufficient cardiac output with maintained peripheral resistance (e.g., heart failure) (Sharma et al., 2023).
Hypovolemic shock is a loss of total blood volume, so blood pressure is not maintained. In this type, the body retains cardiac output and total peripheral vascular resistance (Sharma et al., 2023). This can occur in situations of extreme dehydration.
Obstructive shock occurs when the cardiovascular system is blocked or compressed, inhibiting blood flow so the heart cannot maintain stroke volume (Sharma et al., 2023).
Here is a table with hypotensive measurements and a typical patient’s possible symptoms (Toshi, 2024).
Diagnosis of Hypertension
Hypertension is the term for "high" (hyper) blood pressure (tension). Elevated blood pressure is any measurement over 120/80 mmHg. Depending on the measurement, there are different categories and types of hypertension:
Stage 1 hypertension is a systolic pressure of 130-139 and diastolic of 80-89 mmHg.
Stage 2 hypertension is a systolic of 140 or higher and a diastolic of 90 or higher.
Hypertensive crisis is an emergency, and the person must seek medical attention immediately. This occurs when the systolic blood pressure is over 180, and the diastolic is higher than 120 mmHg.
Essential hypertension is high blood pressure without an identifiable underlying cause.
Secondary hypertension is high blood pressure from a disease process or illness.
Resistant hypertension is high blood pressure that is very difficult to control even with pharmaceutical intervention. Usually, patients with this diagnosis require multiple medications to stabilize their blood pressure.
Malignant hypertension is high blood pressure that is causing organ damage. This type is a medical emergency.
Isolated systolic hypertension is a systolic blood pressure of 140 mmHg or higher and a diastolic of less than 90 mmHg. This can occur with age as the blood vessels thicken.
Labile hypertension is an uncontrollable change in blood pressure. For example, the pressure can suddenly reach 140/90 mmHg or higher and quickly return to normal.
Preeclampsia (or toxaemia) is the development of hypertension during pregnancy. Women at risk of this usually develop gestational hypertension. If unmonitored, this can lead to eclampsia (hypertension causing seizures and coma).
Here is a chart demonstrating the different stages of hypertension and corresponding blood pressure measurements (American Heart Association, 2024).
Treatment of Hypertension
Hypertension is still challenging to treat. Many techniques, like surgeries, diets, and medications, have been tried throughout the years to block certain nerve endings. In 1900, sodium thiocyanate was used to treat hypertension by causing vasodilation and reducing resistance to blood flow (Ensunge, 1991). It was a very unpopular treatment as it was toxic and caused many side effects. In 1904, research by Ambard found that a reduced sodium intake (sodium restriction diet) would reduce blood pressure and the risks of morbidity and mortality that come with having hypertension (Graudal et al., 2020).
In 1923, the first surgical sympathectomy for essential hypertension was done by Fritz Bruening (Ensunge, 1991). A surgical sympathectomy is the cutting of parasympathetic nerves in the vertebral column. The parasympathetic nervous system (relaxes the body) supplies the internal organs and blood vessels. This has been seen to reduce blood pressure but is not a recommended procedure for every patient (Allen, 1952). Chemical sympathectomy was introduced around the same time in the 1920s. This procedure consists of an injection of medication (tetraethylammonium chloride or hexamethonium) into the spinal column rather than an invasive surgical procedure with similar outcomes (Ensunge, 1991).
Based on research on reduced sodium intake in treating hypertension, the Rice Diet became popular in the 1940s (Ensunge, 1991). The diet involves mainly eating rice and fruit while limiting the amount of protein and sodium eaten. Between 1947 and 1960, Freis studied antimalarial medications (pentaquine, bretylium, and guanethidine) as therapy for hypertension. These drugs were never clinically used as they had disturbing side effects. However, they did lower blood pressure and reduced several complications (e.g., neuroretinitis, congestive heart failure, and headaches) in patients with malignant hypertension (Freis, 2005). Hydralazine (Apresoline) is a vasodilator that was introduced in 1949 and is still used today to treat toxaemia (preeclampsia).
In 1957, Freis, Wilsona and Parish introduced the first orally effective diuretic, chlorothiazide (Ensunge, 1991). Diuretics work by inducing the body to excrete excess fluids in the body. The kidneys filter the blood and excrete urine, eliminating the fluids in the blood vessels and reducing the blood pressure. Diuretics are still used today (e.g., furosemide or Lasix) to treat hypertension and fluid overload (e.g., pulmonary edema).
The 1960s saw the rise of calcium channel blockers (nifedipine and verapamil). When calcium enters the cells of a muscle, it causes that muscle to contract tightly. Since these medications block calcium from entering the heart muscle, it does not contract so hard during a heartbeat, and the blood pressure is lowered. Amlodipine (Norvasc) is a calcium channel blocker and one of the most commonly used medications today for hypertension. In 1964, beta-blockers (propranolol and alpha-methyl-dopa) were created. These slow down the heart rate, making it easier for the heart to function. Today’s popular beta blockers are metoprolol (Lopresor) and labetalol (Trandate).
Research in the 1970s found that angiotensin II receptor blockers (ARBs) and renin inhibitors had a similar mechanism of action on the body to block the activity of renin (Taylor, 2011). Renin produces angiotensin II, which increases blood pressure. By blocking the receptors or reducing the renin production, they can be used to treat hypertension. Common ARBs used today are losartan (Cozaar) and candesartan (Atecand).
Timeline Throughout History: Pharmaceutical Interventions for Hypertension
This overview of blood pressure, hypotension, and hypertension gives us a glimpse into the hard work of thoroughly assessing a patient. Let me know if you learned anything new by posting a comment!
– V. A. Cyr
References
Ajanta Pharma USA. (n.d.). Captopril Tablets, USP 12.5 mg [Image]. https://ajantapharmausa.com/product/captopril-tablets-usp-12-5-mg/
Allen, E. V. (1952). Sympathectomy for Essential Hypertension. Circulation, 6, 131―140. https://www.ahajournals.org/doi/pdf/10.1161/01.CIR.6.1.131
American Heart Association. (2024). Healthy and unhealthy blood pressure ranges [Image]. https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings
Arab, S. (2018). Where do you take blood pressure when you can't use the arms? [Image]. Quora. https://www.quora.com/Where-do-you-take-blood-pressure-when-you-cant-use-the-arms
Baxter. (n.d.). Welch Allyn® Connex® Vital Signs Monitor [Image]. Hillrom. https://www.hillrom.ca/en/products/connex-vital-signs-monitor/
Baxter. (n.d.). Welch Allyn® 767-Series Wall / Mobile Sphygmomanometers [Image]. Hillrom.
https://www.hillrom.ca/en/products/767-series-wall-mobile-sphygmomanometers/
Bruss, Z.S. & Raja, A. (2022). Physiology, Stroke Volume. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK547686/
Calvo-Vargas, C. G. (1996). A centennial of two great discoveries in the history of medicine: hyperpiesis and the sphygmomanometer (1896-1996) [Spanish]. Gaceta Médica de México, 132(5), 529―534. https://pubmed.ncbi.nlm.nih.gov/9011515/
Camber Pharmaceuticals Inc. (n.d.). Losartan [Image]. https://www.camberpharma.com/products/losartan/
Campbell, M., Sultan, A., Shumway, K. R. & Pillarisetty, L. S. (2023). Physiology, Korotkoff Sound. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK539778/
DDP Medical Supply. (n.d.). Hydralazine 50mg, 100ct Tablets [Image]. https://ddpmedical.com/hydralazine-50mg-100ct-tablets/
DeMers, D. & Wachs, D. (2023). Physiology, Mean Arterial Pressure. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK538226/
Empower Pharmacy. (n.d.). Hydrochlorothiazide (HCTZ) Tablets [Image]. https://www.empowerpharmacy.com/compounding-pharmacy/hydrochlorothiazide-hctz-tablets/
Esunge, P. M. (1991). From blood pressure to hypertension: the history of research. Journal of the Royal Society of Medicine, 84(10), 621. 10.1177/014107689108401019
Freis, E. D. (2005). Chapter 1 - A History of Hypertension Treatment. Hypertension (2nd ed.), 1―6. https://doi.org/10.1016/B978-0-7216-0258-5.50091-0
Graudal, N. A., Hubeck-Graudal, T. & Jurgens, G. (2020). Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database Systematic Review, 12(12). 10.1002/14651858.CD004022.pub5
Green Pharmacy. (n.d.). Propranolol HCL ER 160MG [Image]. https://greenpharmacyonline.com/rx-products/propranolol-hcl-er-160mg-277.html
Henry Schein Medical (n.d.). Nifedipine 60mg 100/Bt [Image]. https://www.henryschein.com/us-en/medical/p/pharmacy/rx/nifedipine-er-tablets/1409463
Homan, T. D., Bordes, S. J. & Cichowski, E. (2023). Physiology, Pulse Pressure. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK482408/
Jones, A. & Pratt, O. (2009). Fig. 1 A typical IABP measuring system [Image]. https://resources.wfsahq.org/atotw/physical-principles-of-intra-arterial-blood-pressure-measurement/
King, J. & Lowery, D. R. (2023). Physiology, Cardiac Output. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK470455/#
Khan, G. (2006). Hypertension. Encyclopedia of Heart Diseases, 469―491.
https://doi.org/10.1016/B978-012406061-6/50071-0
Lau, C. P. (2016). The sphygmograph. Hong Kong Medical Journal, 22(4), 402―403. https://www.hkmj.org/abstracts/v22n4/402.htm
Lewis, O. (1994). Stephen Hales and the measurement of blood pressure. Journal of Human Hypertension, 8(12), 865―871. https://pubmed.ncbi.nlm.nih.gov/7884783/
Littman. (n.d.). Prosphyg 760 Adult Blood Pressure Monitor (23-40cm)
[Image]. Stethoscope. https://stethoscope.ca/products/prosphyg-760-adult-blood-pressure-monitor-23-40cm?variant=44514879570210
Med Supplies. (n.d.). BIOS Automatic Blood Pressure Monitor [Image]. https://www.medsupplies.co/bios-automatic-blood-pressure-monitor.html
Merriam-Webster. (2024). Tension Definition & Meaning. Merriam-Webster Dictionary. https://www.merriam-webster.com/dictionary/tension
Mirdamadi, A. & Etebari, M. (2017). Comparison of manual versus automated blood pressure measurement in intensive care unit, coronary care unit, and emergency room. ARYA Atheroscler, 13(1), 29―34. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5515188/
Nguyen, Y. & Bora, V. (2023). Arterial Pressure Monitoring. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK556127/#
National Heart, Lung, and Blood Institute (NHLBI). (2022). Low Blood Pressure. National Institutes of Health. https://www.nhlbi.nih.gov/health/high-blood-pressure/causes
National Heart, Lung, and Blood Institute (NHLBI). (2024). High Blood Pressure: Causes and Risk Factors. National Institutes of Health. https://www.nhlbi.nih.gov/health/high-blood-pressure/causes
O'Rourke, M. F. (1992). Frederick Akbar Mahomed. Hypertension, 19(2), 212―217. 10.1161/01.hyp.19.2.212
Ramburger, L. (2022). Normal Blood Pressure By Age: What You Need To Know [Image]. Oak Street Health. https://www.oakstreethealth.com/normal-blood-pressure-by-age-what-you-need-to-know-1100608
Roguin, A. (2006). Scipione Riva-Rocci and the men behind the mercury sphygmomanometer. International Journal of Clinical Practice, 60(1), 73―9. 10.1111/j.1742-1241.2005.00548.x
Sharma, S., Hashmi, M. F. & Bhattacharya, P. T. Hypotension. (2023). StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK499961/
Sharman, J. E., Tan, I., Stergiou, G. S., Lombardi, C., Saladini, F., Butlin, M., Padwal, R., Asayama, K., Avolio, A., Brady, T. M., Murray, A. & Parati, G. (2023). Automated 'oscillometric' blood pressure measuring devices: how they work and what they measure. Journal of Human Hypertension, 37(2), 93―100. 10.1038/s41371-022-00693-x
Taylor, A. A., Siragy, H. & Nesbitt, S. (2011). Angiotensin receptor blockers: pharmacology, efficacy, and safety. Journal of Clinical Hypertension, 13(9), 677―686. 10.1111/j.1751-7176.2011.00518.x
Thermo Fisher Scientific Inc. (n.d.) Sodium Thiocyanate, Crystal, ACS, 98%, Spectrum™ Chemical [Image]. https://www.fishersci.ca/shop/products/sodium-thiocyanate-crystal-acs-98-spectrum-chemical/p-7166371
Thuoc Dantoc. (n.d.). Thuốc Bretylium tosilate được chỉ định để chống loạn nhịp tim, chống rung tâm thất [Image]. https://thuocdantoc.vn/thuoc/bretylium-tosilate
Toshi, N. (2024). How To Manage & Prevent Low Blood Pressure? [Image]. PharmEasy. https://pharmeasy.in/blog/low-blood-pressure-precautions-and-ways-to-manage-it/
Welcome Library. (2018). A sphygmograph, probably of Etienne-Jules Marey's design [Image]. https://en.wikipedia.org/wiki/Sphygmograph#/media/File:Engraving;_direct_sphymograph;_E.J._Marey_Wellcome_L0012232.jpg
Wood Library-Museum of Anesthesiology. (2024). Dinamap 1045 [Image]. https://www.woodlibrarymuseum.org/museum/dinamap-1045/
Wood Library-Museum of Anesthesiology. (2024). Riva-Rocci Sphygmomanometer [Image]. https://www.woodlibrarymuseum.org/museum/riva-rocci-sphygmomanometer/
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