Evidence based practice

INTRADIALYTIC HYPOTENSION

This essay describes about intradialytic hypotension in haemodialysis patients. It is a one of the complications during the hemodialysis. The other complications are Cramps, febrile reactions, arrhythmia, haemolysis hypoxemia.( http://classes.kumc.edu/) . I am currently working in a haemodialysis unit with 15 stations with a total of 90 patients. Patients with established renal failure (ERF) undergoing treatment of haemodialysis (HD) often have side effects during treatment of haemodialysis such as nausea, dizziness, cramps, vomiting, and cardiac condition. The most common complication in the dialysis is an intradialytic hypotension (IDH). Fluid which has accumulated in inter dialysis period has to be removed within a short period of time. Significant changes in the extracellular fluid environment of the patient may occur, which can lead to symptomatic hypotensive episodes. It continues to be a very common complication especially in the elderly and cardio vascular compromised patents. The pathophysiology can be explained by the fact that structural and functional abnormalities of the heart and blood vessels which increase the sensitivity of patient to changes in fluid status. Episodes of hypotension are uncomfortable and distressing for a patient that leads to morbidity, sometimes contribute to cardiovascular mortality. (Levyet al, 2004). So it is very important to prevent hypotension especially in the elderly and vulnerable patient remains a challenge to dialysis nurse and doctors( Frank M et al).

In this essay I am going to talk about the definition of hypotension, control and preventive measures of intradialytic hypotension and deliver effective haemodialysis treatment as recommended by Dialysis Outcomes Quality Initiative (National Kidney Foundation 2002). Critical evaluation, evidence of critical analysis, literature, articles, evidence base journals, renal nursing textbooks and handbooks, accessed some resources from my work area, opinions from my senior nurses and manager.

Harrison Medical Pocket Dictionary (2000) defines “ hypotension as a condition in which the arterial blood pressure is abnormally low. It occurs after excessive fluid loss”. K/DOQI Guidelines cause IDH as decrease in systolic blood pressure by >20 mmHg or a decrease in MAP by l0mmHg associated with symptoms that include: abdominal discomfort, yawing, sighing, nausea, vomiting, muscle cramps, restlessness, dizziness or fainting and anxiety. IDH occurs in (20% to 30%) of dialysis session with patients having haemodialysis treatment. (Daugirdas, Black and Ing 2001).

K/DOQI Guidelines recommended a number of strategies that the dialysis nurse can adopt in order to minimize risk of IDH such as, avoid excessive ultra filtration, slow ultra filtration rate, isolated ultra filtration, increase the dialysate sodium concentration, bicarbonate buffer dialysate, reduce dialysate temperature, correction of anaemia to the range recommended by NKF/KDOQI. Anaemia Guidelines and administer supplemental oxygen. 1 will discuss only some few aspects which we are often use in my unit while our

patients experiencing hypotensive episode during haemodialysis treatment. UF (ultra filtration) profiling, dialysate temperature, sodium profiling, ISO (isolated) UF,

blood volume monitoring (BVM) and dry weight. Before commencing dialysis, the nurse should carry out holistic pre assessments which include discussing with patient about any special concerns especially in his or her general health condition or any un expected events in previous dialysis session. Go through the previous dialysis history and previous notes and asking about any problems occurred during dialysis or post dialysis. Measurement of blood pressure , fluid allowance and clinical assessment. This will help the nurse to asses dry weight. (Thomas N, 2008). The treatment of IDH includes the use of trendlenbug’s position and saline bolus to increase the systolic blood pressure to 100-110mm of Hg (NKF/KDOQI guidelines for cardiovascular disease in dialysis patients)

UF Profiling:

UF profiling is also one of the preventive measures in IDH. Donauer et al (2000) state that UF profiling removes greater portion of fluid during the earlier part of the dialysis and decreasing the rate of fluid removal towards the end of the dialysis treatment. Physiologically this allows fluid to be removed from the plasma when there is sufficient extra fluid in the extra vascular compartment to maintain a strong hydrostatic pressure and facilitate vascular refilling. Movement of fluid from the extra to the intravascular space is likely to be higher at the beginning of dialysis before many of the blood solutes are removed by diffusion.

A study of Donauer, Kolbin, Bek, Krause and Bohler (2000) followed 183 dialysis sessions in 53 patients compared the incidence of symptomatic hypotension between the numbers of UF profiles. 6 treatment regimens were examined: UF profile0, with constant UF rate; UF profile 1, with a linear decreasing UF rate; UF profile 2, with a stepwise decreasing UF rate; and UF profile 3 through 5, with intermittent high UF rates interrupted by UF pause. They found that IDH occurred in 10.6% of treatments when UF rate was constant but only 5.7% of treatments involving a linear decreasing UF rate less episodes of IDH, but there was no large difference between constant UF rate and linear decreasing UF rate because not all patients could tolerated these technique and they failed to get correct statistical significance numbers. But my observation and experience, patients are more comfortable with UF profiling especially with large amount of fluid to remove most of our patients in my unit with more than 2 litres to remove usually are on UF profile. The machine we use in our unit have a 6 different profile options and each patient have their own preference which one to use or on which one they feel more comfortable with. However, these patients sometimes experienced hypotension and complaining of muscle cramps at the end of their dialysis treatment because they have been already removed much fluid during first half dialysis. As a result, saline will be given causing post dialysis thirst and overload of fluid. So achievement of dry weight is not possible. For this strategy each nurse working in a haemodialysis unit must have an adequate knowledge and observation on patient’s treatment and which UF profile would patient comfortable and tolerate with to minimize risk of hypotension and get target to achieve dry weight.

Dialysate temperature:

K/DOQI Guidelines state that during standard dialysis, an increase in the core body temperature is usual and increase the risk for IDH. The increase in the body temperature is either related to heat load from the extracorporeal system or secondary to volume removal. The use of low dialysate temperature (i.e. lower than the patients core temperature) compared with standard dialysate temperature, decrease the frequency and intensity of symptomatic hypotension. Low temperature dialysis improves the reactivity of capacitance and resistance vessels and is associated with improvement in cardiac contractility. But Dougirdas, Black and Ing (2004), mentioned that if patient dialysed against a cool dialysis solution, feels uncomfortable cool and shiver while on dialysis.

Teruel, Martins, Merino, Marcen and Ortuno (2006). In their study, the effect of dialysate

temperature on haemodynamic stability while patients on dialysis, discomfort

intradialytic hypotension and post dialysis fatigue were assessed. 31 patients of the

morning shift were eligible to participate in the study. Three patients refused. Patients

were assessed during 6 dialysis sessions: in three sessions the dialysate temperature was (37 o C) and in other three sessions the dialysate temperature was low (35.5oC). To evaluate the symptoms along the dialysis procedure, intradialytic and post dialysis hypotension and fatigue, specific scale questionnaires were administered in each dialysis session and respective score were assessed. Low temperature dialysate was associated with higher post dialysis systolic blood pressure (122 +/ -24 vs. 126 +/-11 mmHg), and lower post dialysis heart rate (82+/-13 vs. 78 +/- 9 beats/min) with the same ultrafiltration rate. Dialysis symptoms score, IHD and post dialysis fatigue score were better with the low dialysate temperature. Observed patients with high dialysate temperature with higher

dialysis symptoms, IHD and post dialysis fatigue score was high and having more than one episode of hypotension in a week. The patients were asked about their temperature preference, 61% patients’ preferred to be dialysed with the low temperature dialysate.

Another study performed by Ayoub and Finlayson (2004) about the effect of cool temperature dialysate.This was used to test in 2 groups of patients, group one was dialysed with cool dialysate and group two was dialysed with standard dialysate temperature. The results showed group one with cool dialysate increase ultrafiltration without affecting patients’ blood pressure. According to their conclusion they state that cool dialysate improves tolerance for dialysis in hypotensive patients and helps increase ultrafiltration with maintaining haemodynamic stability during and after dialysis compared to the second group with standard dialysate temperature. My own experience, this method is more effective and beneficial particularly to patients with prone to hypotension. In my most of our patients are dialysed with a cool dialysate temperature (35- 360 C) and we achieved less incidence of hypotension. I noticed that some patient with fluid overloaded, using this method is more beneficial for them and their blood pressure during dialysis keep them stable and we achieved our goal to remove more fluid from patients without any risk of hypotension. Therefore educate all staff and new staff about patient’s correct treatment and prescription while they are working in the

haemodialysis unit to reduce the risk of hypotension and run the unit efficiently.

Sodium profiling:

This is another method recommended by K/DOQI Guidelines can be used to prevent or minimise symptoms of hypotension and cramping by optimizing vascular refilling. Dialysate sodium is set at high level during the first hour (or 2) of dialysis and then either stepped downwards in intervals or reduced gradually over the next 3 hours (Levy, Morgan and Brown 2001).

(Studies done by Tang et al (2006) evaluate the effectiveness of sodium profiling in reducing hypotensive episodes and symptoms during haemodialysis. They examined 13 patients who experienced frequent episode of hypotension and symptoms such as cramps, dizziness, chest pain, nausea, vomiting and headache during haemodialys in the

preceding 4 weeks. Each patient was switched from standard haemodialysis with a constant dialysate sodium concentration of 135 to 140 mmol/L to profiling sodium haemodialysis for a period of 4 weeks. During this time the dialysate sodium concentration was linearly downwards from 150mmol/L at the beginning of dialysis to 140 mmol/L at the end of the dialysis. Switching from constant sodium haemodialysis to sodium profiling haemodialysis resulted in a reduction in the number of intradialytic hypertensive episodes

But post dialysis systolic and diastolic blood pressures were higher during sodium profiling haemodialysis compared with constant sodium haemodialysis, and there was a trend towards a smaller droop in blood pressure after dialysis. The intradialytic weight gain was greater with the sodium profiling haemodialysis. However sodium profiling during haemodialysis effectively reduces hypotensive episodes and intradialytic symptoms. Post dialysis blood pressure is better maintained. But a side effect of sodium profiling is greater intradialytic weight gain. They state that sodium profiling increase weight, thirst, post dialysis hypertension fatigue and failed to achieve their dry weight.

Another audit was performed by Devonport (2006) state that increasing dialysate sodium concentration, gaining intradialytic weight and increase blood pressure. An audit was performed in 469 maintenance regular haemodialysis patients who dialysed in seven different centres under the care of one university medical school. Those centers which used dialysate sodium of 140 mmol/L (mEq/L) had increased intradialytic weight gains, which more difficult blood pressure control and the greater percentage patients require anti hypertensive medication/A reduction in dialysate sodium was associated with lower intradialytic weight gains and less percentage patients require antihypertensive medication and controlling blood pressure without additional proper dietary sodium restriction. So again if sodium profiling set up too high in the beginning patient get intradialytic weight gain become thirsty, drink more fluid and cannot achieve target dry weight. If its low patients occasionally experienced hypotension and cramps towards end of the dialysis as a results hypertonic saline will be infused causing patient go away with overload fluid and cannot meet target dry weight..

Isolated ultrafiltration:

A study by Jones, Ward, Hoenich and Kerr (1977) state that ultrafiltration alone for fluid removal has been used and assessed in a number of clinical studies. A paired study of ultrafiltration alone against haemodialysis has shown, that as compared to haemodialysis, ultrafiltration alone within the ultrafiltration rates used is well tolerated. The use of ultrafiltration alone for both acute and chronic fluid overload has been shown to be an ideal therapeutic procedure. But there was no advantage of regular haemodialysis.

K/DOQI Guidelines states that patients with excessive weight gain should be encourage decreasing their fluid intake by performing isolated ultrafiltration with increase duration of haemodialysis treatment but losing for diffusive clearance. However, using this strategy need to be extended the haemodialysis treatment so that compensation is made for the time lost for adequacy or diffusive clearance. In my work place we do isolated ultrafiltration for our patients probably when patient is overload, puffy, oedematous and unable to achieve her or his dry weight. But this method is not obviously use for regular haemodialysis. Additional

measure, three days haemodialysis treatment, performing one day isolated ultrafiltration with educating patient about fluid restriction reduce the risk of hypotension and fluid overload in patients.

Blood volume monitoring:

Another method reducing the risk of hypotension related to slow refilling is the use of blood volume monitoring (BVM). Some machines have this device as an integral part of the machine but a separate monitor can be used. Changes in blood volume are measured through haematocrit and oxygen saturation of the blood. The machine will alarm when the patient is at risk of hypotension (Smith 2000).Levy, Morgan and Brown (2001) state that continuous optical measurement of haematocrit or plasma protein concentration will allow assessment of blood volume by change in concentration of haemoglobin or plasma protein. A decrease in blood volume >8 – 10 % per hour indicates that hypovolemia is imminent. But an individual patient has a relative blood volume (RBV) limit below which hypotension occurs. This is useful when performed repeatedly but there are large inter-patient variations in responses.

A study performed by Germain, Steuer and Cheung (1998) Fluid removal guide by changing blood volume during routine haemodialysis to detect fluid overload. Intradialytic changes in blood volume were continuously monitored by measuring haematocrit. There were 56 patients in a single dialysis unit over 7 weeks. After one week, patients categorized in to two separate group’s depending on their maximum intradialytic decrease in blood volume. In group one 46 of 56 patients, in 82% more than 5 % had decreased in blood volume and group two 10 of 56 patients, in 18 % less than 5 % had decrease in blood volume and they found that during 2 to 7 weeks dialytic fluid removal was increase in group two. The resulted in a larger intradialytic decrease in body weight and a larger intradialytic decrease in blood volume than experienced during week one with a low incidence of symptomps.They conclude that there is a significant percentage of chronic haemodialysis patients who can tolerate additional fluid removal without hypovolemic symptoms even though they are considered to be at dry weight by routine physical examination and that the identification of these patients can be facilitated by using blood volume monitoring. In this perspective, intradialytic blood volume monitoring may prove extremely useful in reducing the incidence of IDH during HD treatment. By the use of BVM helps to detect inadequately high dry weight that may reduce the incidence of chronic volume overload, hypertension and cardiovascular morbidity. My own opinion this method is safe and effective but this tool is bit complicated need to have training and practice for all members of nursing staff in the

unit. In my work place we have only few BVM machines, sometimes it is impossible to

use this method for all patients. We use this tool when patient is new, malnourished, flu.

in and out from the hospital and unable to assessed their dry weight. Criteria cannot meet to get target dry weight

Dry weight:

The term of dry weight (ideal body weight or target weight) the weight at which there is no clinical evidence of oedema, shortness of breath, increased jugular venous pressure or hypertension. (Smith 2000). Fluid balance is an integral component of haemodialysis treatments to prevent under or over hydration. Fluid removal is usually achieved by ultrafiltration to achieve a clinically derived value for “dry weight” (Jaeger and Mehta 1999). Dry weight can usually estimate by trial and error and assessed by episode of hypotension, overt volume overload or hypertension (Levy, Morgan and Brown 2004). Dougirdas, Blake, Ing (2001) states that if the dry weight is set too high, the patient will remain fluid overload at the end of the dialysis session and if set too low the patient may frequently suffer with hypotensive episodes during or the latter part of

The dialysis treatment.

Most of our patient’s dry weight ray change over a period of 3 to 6 weeks (K/DOQI 2000). Our doctors and nursing staff should look in to patient’s clinical features including blood pressure, any signs of oedema, shortness of breathing, jugular venous pressure, intradialytic weight gain and patient’s diet, what they eat and make sure each patient must seen by dietician. If we look in to patient’s dry weight it is essential to look at patient’s experience of hypotensive episode during haemodialysis or patients might left

with fluid overloaded post dialysis, Dry weight is also determined through trial and error

basis. Nurses should have confident and best experienced to assessing patient’s dry

weight. Accurate clinical assessment asking patient’s past medical history, patient’s appearance, how much urine patient passes in 24 hrs, dietary history about appetite,

treatment of haemodialysis, fluid restriction, diet, salt, and their medication. Schreiber (2001) states that, an understanding of the pathology, appropriate dialysis prescription modification, application therapies and development of strategies prevent IDH. Patients should have their data set as part of their pre dialysis assessment to achieve dry weight with understanding individual risk of IDH.

My recommendation I have found some evidence during my essay to give information about the several methods can be used to prevent IDH. We use several methods in our unit. UF profiling gets less incidence of hypotension but end of the dialysis patient gets cramp. According to my practical view I will prefer the method with low dialysate temperature is more effective method and only few side effects to the patients, less hypotensive episodes, and achieved target dry weight. There was another evidence showed about sodium profiling may be effective treatment to reduced risk of

hypotension but disadvantage is increased intradialytic weight, patient get thirsty and hypertensive during dialysis. Isolated UF is good to achieve dry weight, but it is not acceptable in regular haemodialysis treatment need to be extend dialysis treatment time which some patients refused due to tiredness and lost for adequacy. Blood volume monitoring is easy and safe to use but unable to use for all patients due to less availability of BVM parameters and inadequate knowledge, only adequate knowledge to those staff that is trained in that area for long time. None of these above which are beneficial unless the patients dry weight is correct. There is only one and last question is patient’s dry weight. For dry weight is the most important aspect for our patient’s assessment, incorrect individual assessment may leave patients being overload or hypotensive. Therefore a recommendation is an educating the staff towards our clinical practice and work area according to K/DOQI Guidelines to reduced haemodialysis complication and achieve best quality treatment of haemodialysis in each unit. Clinical training sessions on IDH risk recognition and appropriate treatment should be implemented within the each dialysis unit. Each member of staff has to go for further education in order to deliver more effective and efficient treatment to haemodialysis patients. Preventive strategies can be developed in each unit to decrease the number of future IDH events. During this course I have learn a lots and it will help me to improve my skills towards my clinical area, to be a more confident in my work and gain more knowledge and experience in my future practice)

CONCLUSION:

The main issues in the prevention of intradylatic hypotension are mainly blood volume preservation and improvement of cardiovascular stability . In the future it may become possible to integrate blood volume monitoring, blood temperature monitoring and sodium profiling , within a closed-loop of bio feed back system. Which automatically set the U.F rate the dialysis sodium concentration, and the dialysate temperature. Even though all those parameter have to be calculated individually and applied to each patient. There for the introduction of such a automated device can be help in the prevention of intradialyatic hypotension.( Van der Sande et al, 2000) But will never replace the personalised care of the patient by doctors and nurse. In my essay I have covered and discussed the different methods that we could use for patients who prone to intradialytic hypotension. There were all methods have got advantages and disadvantages the best method use in my clinic area is the low dialysate or cool dialysate temperature (Rezki et al, 2007). These was the more effective interventions with few side effects to patients, less hypotensive episode were noted and achieved target dry weight.

References

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Van der Sande FM, Kooman JP, Leunissen KML: Strategies for improving hemodynamic stability in cardiac compromised dialysis patients. Am J Kidney Dis 2000;35:E19

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Dougirdas, J.T; Blake, P.O. & Ing, T. S. (2001) Handbook of Dialysis. (Third Edition) Philadelphia: Lippincott Williams and Wilkins.

Germain, MJ; Steuer, R.R. & Cheung, A.K. (1998) Enhanced fluid removal guide by blood volume monitoring during chronic haemodialysis. Artificial Organs 22 (2) 627-632

Harrison, L.M; (ed) (2000) Medical Dictionary. Delhi: Jahangeer Offset Press.

Jaeger, J. & Mehta, L. (1999) Assessment of dry weight in haemodialysis an overview. Journal of the American society of nephrology 10 (2) 1046-66

Jones, E.O; Ward, M.K; Hoenich, N.A. & Kerr, D.N. (1977) Separation of dialysis and ultrafiltration does it really help. Proceeding of the European Dialysis and Transplant Association 14:160-166

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Rezki H, Salam N, Addou K, Medkouri G, Benghanem MG, Ramdani B. Comparison of prevention methods of intradialytic hypotension. Saudi J Kidney Dis Transpl 2007;18:361-4

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Available

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