Blood pressure monitoring is a vital part of small animal practice, and is often the responsibility of the veterinary nursing staff. Learn the indications for measurement and normal and abnormal blood pressure values. Show
December 19, 2014 | Lila K. SierraCVT, VTS (Emergency and Critical Care) Lila K. Sierra, CVT, VTS (Emergency and Critical Care) is the assistant nursing supervisor of the intensive care unit at Matthew J. Ryan Veterinary Hospital of University of Pennsylvania. She has lectured at state conferences and has published chapters in various veterinary manuals. Her passion lies in all aspects of advanced nursing care, including patient advocacy, innovative nursing development, and education of prospective veterinarians and nurses. Read Articles Written by Lila K. Sierra Emily SavinoBA, CVT, VTS (Emergency and Critical Care) Emily Savino, BA, CVT, VTS (Emergency and Critical Care) is the nursing supervisor of the intensive care unit at Matthew J. Ryan Veterinary Hospital of University of Pennsylvania. She has lectured on veterinary critical care nursing at conferences, and has published chapters in veterinary texts. She enjoys teaching new veterinary nurses the art of “critical thinking” and working in an environment where she is learning new things every day. Read Articles Written by Emily Savino Systemic arterial blood pressure is created by the pumping action of the heart, circulating arterial blood volume, and smooth muscle tone of blood vessel walls. Arterial blood pressure is essential for adequate perfusion of tissues, providing oxygen delivery for energy demands. The ability to measure and monitor blood pressure trends provides important data about patient cardiovascular status and may help define approach to treatment. Blood pressure monitoring has become a vital part of small animal practice, and is often the responsibility of the veterinary nursing staff. Veterinary nurses should:
Part 1 of this article series discusses terms associated with blood pressure measurement, indications for measurement, and normal and abnormal blood pressure values. Part 2 will describe types of blood pressure monitors and provide step-by-step instructions on how to perform blood pressure measurement. Blood Pressure DefinitionsBlood Pressure ValuesWhen the left ventricle contracts, blood is pushed into the aorta creating systolic arterial pressure (SAP); then the left ventricle empties, relaxes, and begins to fill again, and aortic pressure falls, creating diastolic arterial pressure (DAP). Mean arterial pressure (MAP) is calculated from the systolic and diastolic values:1 MAP = DAP + 1/3 (SAP–DAP) Types of MonitoringArterial blood pressure can be monitored in 2 ways:
FIGURE 1. Direct arterial blood pressure being monitored in a dog with an arterial catheter in the dorsal pedal artery. The catheter is attached to a disposable pressure transducer system. An inflated pressure bag maintains the system under constant pressure that must be higher than SAP.2 FIGURE 2. Doppler blood pressure measurement. FIGURE 3. Feline patient connected to an oscillometric blood pressure monitor. Indications for MeasurementSpecific indications for blood pressure monitoring include:
Blood Pressure Monitoring: Looking at the “Big Picture”Veterinary nurses should think critically about results obtained in their patients, never looking at 1 value independent of the rest of the patient. In other words, think about your patient globally and consider the patient’s blood pressure reading as part of the bigger picture. For example:
These are the types of questions that veterinary nurses should ask. By taking time to consider the “whole picture” rather than only looking at isolated pieces of information, veterinary nurses are better able to process what may be happening with their patients and pass significant concerns on to clinicians. Normal Arterial Blood Pressure ValuesBlood pressure measurement provides important information about the cardiovascular status of a patient, and the importance of knowing normal values in different species cannot be overstated (Table 1). HypotensionHypotension is defined as lower than normal blood pressure. Hypotension results in decreased tissue perfusion and can result in compromised blood flow to vital organs. Common causes of hypotension are listed in Table 2. DiagnosisA diagnosis of hypotension is made based on the patient’s presentation, physical examination, and blood pressure measurement. In dogs and cats, MAP is the preferred value used for making a diagnosis of hypotension. A patient is considered hypotensive when:
A hypotensive blood pressure reading should be followed by brief physical assessment of the patient, and the clinician should be notified of the patient’s status. MonitoringHypotensive patients should be monitored on a regular basis and their cardiovascular status should be re-evaluated, at minimum, every 30 minutes. Frequent reassessment is necessary to determine whether therapy is working or if more aggressive intervention is necessary. It is important to remember that a patient’s cardiovascular status can decline rapidly. Renal tissue perfusion diminishes when MAP declines below approximately 65 mm Hg.4 In patients with sustained MAP < 65 mm Hg, the patient’s urine output should be monitored closely because decreased urine output can signify impaired renal perfusion. HypertensionHypertension is typically divided into 2 categories: primary and secondary. Primary HypertensionPrimary hypertension is caused by an imbalance between cardiac output and systemic vascular resistance that has no known cause; therefore, it is sometimes referred to as idiopathic hypertension.6,7 It is rare in small animals. A diagnosis of primary hypertension is made when reliable blood pressure readings demonstrate a sustained increase in blood pressure, paired with a normal complete blood count, serum biochemical profile, and urinalysis.6 TABLE 3. Secondary HypertensionSecondary hypertension is elevated blood pressure that occurs secondary to concurrent disease (Table 3), or due to administration of medications, including certain therapeutic agents, such as glucocorticoids, mineralocorticoids, erythropoietin, sodium chloride, phenylpropanolamine, and nonsteroidal anti-inflammatory drugs.6,7 Diagnosis
ConsequencesPersistent elevations in blood pressure can have serious consequences. Sustained hypertension is associated with damage to the eyes, ears, brain, and kidneys.6,7 A hypertensive emergency occurs when the patient has a marked elevation of blood pressure and is at risk for development of end-organ damage or vascular incidents, such as cerebral hemorrhage causing neurologic signs or intraocular hemorrhage causing blindness.7 MonitoringIt is imperative that severely hypertensive patients are treated at a facility that can provide 24-hour critical care monitoring. When “Normal” Does Not Mean All is Well
Accurate Blood Pressure MeasurementStress and anxiety in the clinic setting, coupled with stress during handling to obtain a blood pressure measurement, can cause elevated readings, resulting in a false diagnosis of hypertension. The following steps should be taken to ensure an accurate measurement:
Minimizing the risk of an incorrect diagnosis of hypertension in the fearful or painful patient relies on interpretation of a pet’s body language during the examination, use of a little creativity, and a lot of patience:
White Coat SyndromeSome patients may fall into the category of white coat syndrome, which should not be confused with true hypertension. Unfamiliar faces, scents, and sounds, followed by a close encounter with a stranger in a white coat can inadvertently cause stress, anxiety, and fear, hindering our ability to obtain accurate blood pressure readings. In human medicine, this is a well-recognized phenomenon. Blood pressure surges occur in patients with this condition, making it difficult to ascertain valid blood pressure measurements, and potentially resulting in an inaccurate diagnosis of hypertension.8 SummaryVeterinary nurses play a fundamental role in patient care. We are often on the front lines, assessing patients as they are initially presented and then assessing them repeatedly after the clinician leaves. This gives us unique insight to detect subtle variations that may otherwise go unnoticed. Documenting that information, interpreting it, and communicating changes to the clinician provides the veterinary team an opportunity to proactively manage potential problems. Key to Terms DAP = diastolic arterial pressure; MAP = mean arterial pressure; SAP = systolic arterial pressure References
What is the nurse's role in taking blood pressure?Nurses often are the first health professionals to detect hypertension and therefore have a key role in communicating with patients and other health professionals to enforce treatment guidelines through development and appropriate revision of the patient's treatment plan.
What are the nursing responsibilities while taking vital signs?The nursing responsibilities during vital signs monitoring include taking the patient's history and performing physical examinations. The history includes asking about any medical conditions affecting the patient's health.
When taking the blood pressure correctly the nurse should?Palpate the brachial pulse. If this is the patient's initial reading, determine a target pressure by inflating the BP cuff until you no longer feel the pulse, and note the sphygmomanometer reading at that point. Target pressure inflations will be 30 mm Hg above that reading. Deflate the cuff and wait 2 minutes.
What are the steps to follow when taking blood pressure?Step-by-Step Blood Pressure Check. Locate your pulse. Locate your pulse by lightly pressing your index and middle fingers slightly to the inside center of the bend of your elbow (where the brachial artery is). ... . Secure the cuff. ... . Inflate and deflate the cuff. ... . Record your blood pressure.. |