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Fifteen-minute versus thirty-minute blood pressure evaluation during chronic hemodialysis.

Hypothetical Case

A 65-year-old female arrived at her outpatient dialysis center for her regularly scheduled hemodialysis treatment. The nurse greeted the patient and performed the pre-assessment, including weight, vital signs, heart and lung sounds, evaluation for edema, and subjective evaluation. The patient reported no problems or complaints since her last treatment. Her interdialytic weight gain was 5.0 kg, blood pressure 170/98, heart rate 92, respiratory rate 20 breaths per minute, and temperature 98.2[degrees]. The patient's arteriovenous fistula was cannulated without difficulty, and the dialysis treatment was initiated. Her blood pressure was routinely checked every 30 minutes per facility policy. Three hours into the four-hour treatment, the patient's blood pressure was 132/70, and heart rate was 80. The patient was sleeping and was not awakened. Thirty minutes later, the patient's blood pressure was undetectable, with a heart rate of 30 beats per minute. The patient's blood was returned, a liter of normal saline administered, and resuscitative measures initiated. The patient was sent to the emergency department via Emergency Medical Services with a blood pressure of 70/40 and a heart rate of 60 beats per minute, and she was unresponsive. The patient was diagnosed with an acute myocardial infarction. She was sent to the Cardiac Care Unit and was discharged home one week later with no further complications.

Could this situation have been prevented? If so, what nursing action could be taken to prevent the situation?

Question

What is the recommended frequency for the evaluation of blood pressure during hemodialysis to prevent intradialytic hypotension?

Literature Search

A literature search was conducted using the databases EBSCOHost, Pubmed, and CINAHL to locate evidence regarding the frequency of blood pressure evaluation during hemodialysis procedures. Key words used to identify relevant articles were blood pressure, monitoring, evaluation, hemodialysis, and intradialytic hypotension. The accepted date range for relevant articles was 2000 to present to ensure inclusion of current recommendations.

Introduction

Alterations in blood and fluid volume during hemodialysis predispose patients to potential precipitous changes in blood pressure. Nephrology nurses report various practices regarding frequency of blood pressure, ranging from every 15 minutes to hourly (Hossli, 2005; Palmer, 2009). The question for consideration relates to identifying the best practice for frequency of blood pressure evaluation to prevent intradialytic complications.

Intradialytic blood pressure fluctuations are a common occurrence during the hemodialysis procedure. According to Santos, Peixoto, and Perazella (2012), symptomatic intradialytic hypotension is the most common complication experienced by patients during a hemodialysis treatment, although a small percentage of patients experiences intradialytic hypertension.

Individuals with end stage renal disease (ESRD) receiving hemodialysis are at greater risk for cardiovascular morbidity and mortality because of diabetes, hypertension, vascular calcification, and other factors associated with uremia (Flythe et al., 2012). Flythe and colleagues (2012) have suggested variability of blood pressure during the hemodialysis procedure as a factor that increases morbidity and mortality for the ESRD population receiving long-term hemodialysis.

Physiology of Blood Pressure Control

Perfusion to capillary beds during a wide range of physiologic conditions is maintained through regulation of mean arterial pressure (MAP), the average arterial pressure throughout the cardiac cycle (Guyton & Hall, 2000). The normal range for MAP is 80 to 100 mmHg. Arterial wall elasticity and circulating blood volume are properties that facilitate regulation of MAR Blood pressure will change in response to changes in either factor regulating arterial pressure.

Blood pressure is the product of cardiac output and peripheral resistance (Guyton & Hall, 2000). Guyton and Hall (2000) define cardiac output as total blood volume ejected from the ventricles in one minute, with stroke volume and heart rate as determining factors. Therefore, intravascular volume and myocardial health are key factors affecting cardiac output. Adequate cardiac output can be maintained with approximately 10% loss of blood volume, such as during hemodialysis. As total blood volume decreases, cardiac output decreases with subsequent drop in blood pressure. At around 20% loss of blood volume, blood pressure drops dramatically, which may result in tissue damage to vital organs. The relationship between the percentage of blood volume depletion and blood pressure response is depicted in Figure 1. To compensate for decreasing blood pressure, the heart rate increases along with more forceful myocardial contractility in an attempt to restore blood pressure to a normal physiologic state (Guyton & Hall, 2000).

Peripheral resistance is described as blood flow resistance within blood vessels, primarily affected by blood vessel diameter (Guyton & Hall, 2000). Arterial constriction will raise mean arterial pressure while arterial dilation decreases MAP with corresponding changes in measured blood pressure. Other factors that may influence MAP, therefore blood pressure, include blood viscosity and vessel length. Factors that change either cardiac output or peripheral resistance will lead to changes in blood pressure.

Normally functioning kidneys play a pivotal role in blood pressure control through the renin-angiotensin aldosterone system (Hendry, Farley, & McLafferty, 2012; Peters, 2007). When a fall in blood pressure is detected by the juxtaglomerular cells in the kidney, renin is released, which reacts with angiotensinogen in circulating blood to convert angiotensin to angiotensin I. Vascular endothelium, primarily in lungs but also from heart, brain, and vessels, releases an angiotensin converting enzyme (ACE) to convert angiotensin I to angiotensin II (Peters, 2007).

Angiotensin II causes elevation in blood pressure through several mechanisms. Vasoconstriction of blood vessels acts to increase peripheral resistance. The adrenal cortex is stimulated to release aldosterone, which increases sodium reabsorption and fluid retention. A third function of angiotensin II is stimulation of posterior pituitary to release vasopressin, an anti-diuretic hormone, which further increases fluid retention by the kidneys. All of the described physiologic processes work to maintain a stable blood pressure (Hendry et al., 2012; Peters, 2007).

Hemodynamic Changes During Hemodialysis

Adequate blood pressure management is essential for individual well-being. Due to the hemodynamic changes that occur during hemodialysis, management of blood pressure requires diligent assessment and management. Compensatory mechanisms used by the body to maintain blood pressure while changes in blood volume occur include vasoconstriction, vasodilation, heart rate changes, and vascular refill rate (Charra, 2007). Ventricular dysfunction, vascular tone, autonomic dysfunction, and dialysate composition may have an impact on the ability of compensatory mechanisms to function adequately (Ronco, 2001).

Physiologic changes that occur during hemodialysis are most commonly associated with ultrafiltration, vascular refill, and plasma osmolality (Lindsay, Shulman, Prakash, Nesrallah, & Kiaii, 2003). Ultrafiltration rate and vascular refill need to occur at approximately the same rate to maintain a stable blood pressure during the hemodialysis procedure (Ballantine & Barcellos, 2004). During hemodialysis, blood volume initially decreases within the intravascular compartment leading to an increase in plasma oncotic pressure caused by increase in plasma protein concentration. Increased oncotic pressure and decreased capillary hydrostatic pressure yields a shift in fluid from interstitial space to intravascular space. Hypotension occurs when ultrafiltration rate exceeds interstitial-intravascular refill rate. The refill process may be hampered by a low plasma osmolality. Reduction in osmolality is a result of imbalance of extracellular and intracellular osmotically active solutes leading to less available fluid to refill intravascular space; thus, hypotension occurs (Ishibe & Peixoto, 2004). Flythe et al. (2012) postulate that these pathways underlining ultrafiltration and destabilization of blood pressure may lead to increased cardiovascular mortality.

Implications for Nephrology Nurses

Evidence indicates the importance for prevention of intradialytic hypotension, which occurs in 10% to 30% of hemodialysis treatments (Santos et al., 2012). Sustained, unrecognized intradialytic hypotension may lead to subsequent organ damage to brain, heart, intestines, or lungs, as well as contribute to thrombosis of hemodialysis access (Palmer, 2009; Sherman & Kapoian, 2011). Repetitive occurrences of hypotension during hemodialysis have been associated with cardiac ischemia and/or infarction, cardiac arrhythmias, cerebrovascular accident, and seizures that ultimately lead to higher mortality (Hossli, 2005; Ronco, 2001; Santos et al., 2012). Normal compensatory mechanisms activate in response to hypotension to maintain perfusion to vital organs. Blood pressure may be maintained for 15 to 40 minutes through those mechanisms, which points to the importance of blood pressure monitoring at intervals allowing for early detection and prevention of serious complications associated with hypotension (Guyton & Hall, 2000; Lindsay et al., 2003). Consequently, nephrology nurses have a responsibility to prevent harm to the patient through a proactive effort to prevent complications associated with fluctuations in blood pressure during hemodialysis.

Serious complications from intradialytic hypotension are more pronounced in the elderly, which comprises a large percentage of patients on hemodialysis (Santos et al., 2012). The existence of other co-morbidities, such as diabetes, cardiac disease, and autonomic insufficiency, further intensifies the incidence of hypotension. Although the body attempts to auto-regulate blood pressure, the loss of a large amount of circulating volume within a short time interval may overtax regulatory mechanisms leading to hypotension and organ malfunction. Diligent monitoring of blood pressure accompanied by patient assessment data, interdialytic weight gains, accuracy of estimated dry weight, and patient adherence to the treatment prescription work together to improve outcomes for patients on hemodialysis.

Prevention of hypotensive episodes, however, does not lie only within the domain of nephrology nurses. Patients also have a responsibility to be active participants in personal health care and decision-making. Nephrology nurses are responsible for the provision of education that allows informed decision-making by the patient. Interdialytic weight gains, sodium intake, missing or shortening treatments, and adhering to medication regimen are factors that may influence blood pressure control that are under control of the patient.

Recommendations

A paucity of research studies was found regarding specific guidelines for best practice related to the frequency of blood pressure evaluation during a hemodialysis treatment. Based on the literature review, however, the physiology of blood pressure control and hemodynamic changes that occur during a hemodialysis treatment, blood pressure evaluations at 15-minute intervals as opposed to 30-minute intervals may enable nephrology nurses and other care providers to recognize and prevent dramatic drops in blood pressure. Blood pressure recommendations from National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines indicate the maintenance of a target prehemodialysis blood pressure of 140/90 or less and posthemodialysis blood pressure of 130/80 or less (NKF, 2005).

Conclusion

Through maintenance of blood pressure stability and prevention of intradialytic hypotension, patient morbidity and mortality may be decreased. It is imperative that nephrology nurses recognize that blood pressure monitoring is one component for ensuring quality care, and decreasing morbidity and mortality. Integration of assessment data, estimated dry weight evaluation, and patient adherence are fundamental to the promotion of good health outcomes.

References

Ballantine, L., & Barcellos, B. (2004). A quality initiative--Can we reduce the incidence of hypotension during hemodialysis? CANNT Journal, 14(1), 26-33.

Charra, B. (2007). Fluid balance, dry weight, and blood pressure in dialysis. Hemodialysis International, 11(1), 21-31.

Flythe, J.E., Kunaparaju, S., Dinesh., Cape, K., Feldman., & Brunelli, S.M. (2012). Factors associated with intradialytic systolic blood pressure variability. American Journal of Kidney Diseases, 59(3), 409-418.

Guyton, A.C., & Hall, J.E. (2000). Textbook of medical physiology (10th ed.). Philadelphia: W.B. Saunders.

Hendry, C., Farley, A., & McLafferty, E. (2012). Blood vessels, circulation, and blood pressure. Nursing Standard, 27(11), 35-40.

Hossli, S.M. (2005). Clinical management of intradialytic hypotension: Survey results. Nephrology Nursing Journal, 32(3), 287-292.

Ishibe, S., & Peixoto, A.J. (2004). Methods of assessment of volume stares and intercompartmental fluid shifts in hemodialysis patients: Implications in clinical practice. Seminars in Dialysis, 17(1), 37-43.

Lindsay, R.M., Shulman, T., Prakash, S., Nesrallah, G., & Kiaii, M. (2003). Hemodynamic and volume changes during hemodialysis. Hemodialysis International, 7(3), 204-208.

National Kidney Foundation (NKF). (2005). Kidney Disease Quality Outcome Initiatives (KDOQI): Clinical practice guidelines for cardiovascular disease in dialysis patients. Retrieved from http://www.kidney.org/professionals/kdoqi/guidelines_cvd/index.htm

Palmer, B.E (2009). Preventing intradialytic hypotension. Seminars in Dialysis, 22(5), 489-491. doi:10.1111/j.1525-139X.2009.00643.x

Peters, JJ. (2007). The rennin-angiotensin aldosterone system: Pathophysiological role and pharmacologic inhibition. Journal of Managed Care Pharmacy, 13(8), 9-20.

Ronco, C. (2001). The problem of hypotension in haemodialysis. Nephrology, 6(3), 99-103. doi: 10.1046/j.1440-1797.2001.00054.x

Santos, S.E, Peixoto, A.J., & Perazella, M.A. (2012). How should we manage adverse intradialytic blood pressure changes? Advances in Kidney Diseases, 1.9(3), 1.58-16.5. doi:10.1053/j.ackd.2012.03.003

Sherman, R.A., & Kapoian, T. (2011). Intradialytic hypotension strikes again. Journal of the American Society of Nephrology, 22(8), 1396-1398. doi:10.1681/ASN.2011060541

Exploring the Evidence is a department in the Nephrology Nursing Journal designed to provide a summary of evidence-based research reports related to contemporary nephrology nursing practice issues Content for this department is provided by members of the ANNA. Research Committee. Committee members review the current literature related to a clinical practice topic and provide a summary of the evidence and implications for best practice. Readers are invited to submit questions or topic areas that pertain to evidence-based nephrology practice issues. Address correspondence to: Tamara Kear, Exploring the Evidence Department Editor, ANNA National Office, East Holly Avenue/Box 56, Pitman. NJ 08071-0056; (856) 256-2320; or via e-mail at NNJEvidence@ajj.com. The opinions and assertions contained herein are the private views of the contributors and do not necessarily reflect the views of the American Nephrology Nurses' Association.

Alicia M. Horkan, MSN, RN, CNN, is Assistant Director, Dialysis Services, the Dialysis Center at Colquitt Regional Medical Center, Moultrie, GA; a member of ANNA's Peach Chapter,. and current member of ANNA's Research Committee. The author may be contacted directly via e-mail at amhorkan@windstream.net
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Title Annotation:Exploring the Evidence
Author:Horkan, Alicia
Publication:Nephrology Nursing Journal
Article Type:Report
Date:May 1, 2013
Words:2231
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