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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2009  |  Volume : 20  |  Issue : 4  |  Page : 596-603
Effect of dialysate temperature on hemodynamic stability among hemodialysis patients

Biomedical Engineering Department, Misr University for Science and Technology, 6th of October City, Egypt

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Date of Web Publication8-Jul-2009


Cooling the dialysate below 36.5°C is an important factor that contributes to hemody­namic stability in patients during hemodialysis (HD). In this study, the effect of dialysate tempe­rature on hemodynamic stability, patients' perception of dialysis discomfort and post dialysis fatigue were assessed in a group of patients on HD. A total of 50 patients, all of whom were on 3-times-per­week dialysis regimen, were studied. Patients were assessed during six dialysis sessions; in three sessions, the dialysate temperature was normal (37°C) and in three other sessions, the dialysate tem­perature was low (35°C). Specific scale questionnaires were used in each dialysis session, to evaluate the symptoms during the dialysis procedure as well as post-dialysis fatigue, and respective scores were noted. The results showed that usage of low dialysate temperature was associated with the fol­lowing: higher post dialysis systolic blood pressure (P< 0.05) and lower post dialysis heart rate (P< 0.01), with similar ultrafiltration rates, better intra-dialysis symptoms score and post-dialysis fatigue scores (P< 0.001, and P < 0.001, respectively), shorter post-dialysis fatigue period (P< 0.001) as well as higher urea removal (P< 00001) and Kt/V (P< 0.0001). Patients' perceptions were measured by a questionnaire, which showed that 76% of them felt more energetic after dialysis with cool dialysate and requested to be always dialyzed with cool dialysate. Low temperature dialysate is particularly beneficial for highly symptomatic patients, improves tolerance to dialysis in hypotensive patients and helps increase ultrafiltration while maintaining hemodynamic stability during and after dialysis.

Keywords: Cool Dialysate, Hemodynamic Stability, Hypotensive Episodes, Standard Dialysate, Urea Reduction Ratio, Equilibrated Kt/V, Post dialysis fatigue

How to cite this article:
Azar AT. Effect of dialysate temperature on hemodynamic stability among hemodialysis patients. Saudi J Kidney Dis Transpl 2009;20:596-603

How to cite this URL:
Azar AT. Effect of dialysate temperature on hemodynamic stability among hemodialysis patients. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2021 Nov 29];20:596-603. Available from: https://www.sjkdt.org/text.asp?2009/20/4/596/53247

   Introduction Top

Many studies have shown that cool dialysate improves cardiovascular tolerance among hemo­dialysis (HD) patients and reduces hypotensive episodes during HD. [1],[2],[3],[4],[5],[6] During standard dialysis and ultrafiltration, the combination of low blood volume and loss of peripheral vascular resistance causes hypotension. Blood cooling has been used to stabilize blood pressure (BP) during very high efficiency HD with high ultrafiltration rate, and helps to maintain BP without compromising the efficacy of HD. [7],[8],[9] The increase in BP associated with cool dialysate is due largely, if not entirely, to increased total peripheral resistance and increased venous tone. [10] The use of cooler dia­lysate improves left ventricular contractility, in­dependently of pre-load and after-load. [11] The aim of this study was to assess the impact of dialysate temperature on hemodynamic stability, patients' perception of dialysis quality and on the post-dialysis fatigue syndrome in patients on maintenance HD. This study also aims at studying the effect of using cool dialysate on dialysis efficacy. The study was carried out on a sample of patients selected randomly and compared the response at two bath temperatures: 37°C as the usual temperature, and 35°C as the low tempe­rature. We chose the latter temperature because several studies have shown that this degree of cooling produces the least variations in core body temperature. [9] ,[12],[13],[14]

   Subjects and Methods Top

The study was carried out on 50 clinically sta­ble patients after obtaining informed consent to participate. There were 23 males and 27 female patients, with ages ranging between 28 and 73 years (48 ± 13, mean and SD), and dialysis the­rapy duration ranging between 6 and 96 months (32 ± 28). The etiology of renal failure was chro­nic glomerulonephritis (11 patients), vascular ne­phropathy (9 patients), diabetic nephropathy (11 patients), hypertension (7 patients), chronic in­terstitial nephropathy (5 patients), unknown cause (4 patients), and others (3 patients). The study was carried out between August and October 2007. The vascular access used was a native ar­teriovenous fistula in 45 patients, and a perma­nent jugular catheter in five patients. Seven pa­tients were taking antihypertensive medicines, which were told to be omitted on the day of HD. Regular medications for the selected sample in­cluded phosphate binders. Patients had dialysis three times a week, in 3-4 hour sessions, with arterial blood flow of 300-350 mL/min, and dia­lysate flow of 500 mL/min. The dialysate con­sisted of the following constituents: sodium 141 mmol/L, potassium 2.0 mmol/L, calcium 1.3 mmol/L, magnesium 0.2 mmol/L, chloride 108.0 mmol/L, acetate 3.0 mmol/L and bicarbonate 35.0 mmol/L. All patients used hollow fiber dialy­zers with high-permeability biocompatible mem­brane; 1.8 m 2 polysulphone with an ultrafiltra­tion coefficient of 18 mL/hour/mmHg. The dia­lysis technique was conventional HD on all pa­tients; no patient was on hemodiafiltration. The adjustable parameters during a HD session were kept constant throughout the study. Fluid removal was calculated as the difference between the pa­tients' weight before and after a dialysis session. Pre-dialysis body weight, blood pressure, pulse rate and axillary temperature were measured be­fore ingestion of food and drink. Blood pressure was determined with a digital electronic sphyg­momanometer with the patient in sitting posi­tion, and axillary temperature was measured with a mercury thermometer with glass support. In patients having an arteriovenous fistula, the con­tralateral arm was used for both BP measure­ments. The BP, pulse rate, arterial line pressure, venous line pressure, blood flow rate, transmem­brane pressure and fluid loss were all checked hourly during dialysis. Weight, BP, pulse rate and temperature were recorded post-dialysis. Blood flow during dialysis was slowed to 100 mL/min before collecting post-dialysis blood samples for urea. Mean arterial pressure was calculated as the diastolic pressure plus one­third of the pulse pressure. The urea reduction ratio (URR) was calculated using the formula: urea pre-urea post/urea pre × 100%. [15] Dialysis dose was measured by equilibrated Kt/V (Kt/ V eq ). [16] The single pool Kt/V (Kt/V sp ) was de­termined from the Daugirdas second generation formula. [17] The method of research utilized was single subject multiple probes across partici­pants in each group, over six HD sessions. Du­ring the first three sessions, patients continued having their dialysis with the usual dialysate tem­perature at 37°C; the data of this week were considered as baseline values. During the subsequent three sessions, the dialysate temperature was decreased to 35°C. During the study weeks, the ultrafiltration rate in each dialysis session (expressed in mL and in percentage of lean wei­ght) was noted. The average of the three weekly values was calculated for each patient. The room temperature was controlled and was 23°C at low air movement. The number of hypotensive events the patients had during HD as well as the other symptoms and complications they might have developed were registered. A hypotensive event was defined according to the criteria esta­blished by the DOQI guidelines which refers to a decrease in systolic BP of > 20 mmHg asso­ciated with symptoms. [18] To assess the patients' perception on the symptoms they had during the HD session, a modified version of the question­naire designed by Cruz et al was used. [19] At the end of each dialysis session, during the study weeks, a questionnaire was given to each pa­tient with the following questions: Have you had any discomfort during the dialysis session? Which one? What level of discomfort have you noticed?

If the patient recovered rapidly, the discomfort was considered as being mild, if it persisted for longer than half an hour it was considered mo­derate, and if it persisted throughout the whole session, it was considered as severe. To assess the post-dialysis fatigue syndrome, the modi­fied Sklar et al questionnaire was used. [20] Before each dialysis session, the patient was asked the following: how long did it take to recover from the last dialysis session? Which was the main complaint he/she had? What level of discomfort did he/she experience? The discomfort was con­sidered mild if it did not prevent the patient from doing his/her usual activity, moderate if his/her activity was limited but he/she did not have to take bed-rest, or severe if he/she had to take bed-rest to recover. At the end of the se­cond study week, each patient was asked his/her preference regarding dialysate temperature [nor­mal (37°C) or low (35°C)]. For the subsequent four weeks, each patient was dialyzed using his/her preferred dialysate temperature, and du­ring the last week all the previous parameters were collected again including the questionnaires. All questionnaires were evaluated by the same individual. Statistical analysis was performed using SPSS 14.0 and NCSS 2007 software pa­ckages. Mean errors relative to reference values were compared by one way ANOVA test. The Student's t test was used for both paired and non paired data. P values < 0.05 were considered as statistically significant.

   Results Top

The change noted in clinical parameters by decreasing the dialysate temperature are shown in [Table 1].

There was no change in the post-dialysis axil­lary temperature with the use of dialysate at 37°C, but it decreased with the use of bath at 35°C (P< 0.001). The mean arterial pressure post dia­lysis was significantly higher in patients dia­lyzed with cool dialysate compared with those dialyzed with normal dialysate (P= 0.01). The BP decreased after dialysis with both cool and normal temperature dialysate (P< 0.05 for SBP with both dialysates, P< 0.05 for DBP at 37°C, and P= 0.07 for DBP at 35°C). The heart rate increased with bath temperature at 37°C (P< 0.001) and was not altered with bath tempera­ture at 35°C. The main discomfort experienced by the patients during the HD session was light­headedness; this symptom being the one that most conditioned the "Symptomatology Index" during HD. Other reported symptoms included the fo­llowing: with bath temperature at 37°C, three patients reported feeling hot and uncomfortable, and one patient had cramps; with bath tempe­rature at 35°C, three patients had chills, and two patients had cramps. Two patients had vomiting with both bath temperatures. The main problem experienced by the patients post-dialysis was fatigue, followed by light headedness. One pa­tient complained of post dialysis headache with bath temperature at 37°C, and one other had cramps with bath temperature at 35°C. The im­provement in patients' perception of symptoms and in the number of hypotensive events after decreasing the dialysis bath temperature was particularly relevant in patients who had poor tolerance to HD with dialysate bath temperature of 37°C. At the end of the second study week, the patients were asked their preference regar­ding the dialysate bath temperature: the conven­tional 37°C or, the new 35°C (low temperature). Thirty eight patients (76%) preferred the 35°C dialysate, seven (14%) preferred the 37°C dia­lysate while no specific preference was indicated by the remaining five patients (10%). The vast majority of respondents reported feeling more energetic and having a dramatic improvement in their general health following dialysis with cool dialysate. The results from the question­naire are summarized in [Table 2]. As indicated in [Table 3], the difference in Kt/V eq values with the use of cool dialysate (35°C) and normal dialy­sate (37°C) was statistically significant (P< 0.0001). Usage of cool dialysate resulted in in­creased ultrafiltration, while maintaining hemo­dynamic stability compared with normal dialy­sate (37°C) (P< 0.0001). Also, there was a statis­tically significant difference in the URR bet­ween HD using cool dialysate and normal dia­lysate (P< 0.0001). [Figure 1] and [Figure 2] illustrate the comparison of Kt/V eq and URR between the two dialysate temperatures.

   Discussion Top

In a non-selected HD population, reduction of the dialysate temperature increases hemodyna­mic stability, decreases subjective symptoma­tology during dialysis, and improves post dia­lysis fatigue syndrome. By decreasing dialysate temperature from 37 to 35°C, patients complete the dialysis session with higher systolic blood pressure and lower heart rate, with the same degree of ultrafiltration. [6] ,[12] ,[19] ,[21] The decrease in dialysate temperature increases vascular reac­tivity [14] and achieves better preservation of car­diac output and central blood volume, [21] facili­tating the hemodynamic response to prevent hypotensive episodes. To evaluate the level of discomfort experienced by the patients during the HD session, the modified questionnaire by Cruz et al was used, [19] that allows for a quanti­fication by means of a symptomatology index. Hemodialysis with low dialysate temperature was accompanied by a decrease of this index in the study patients. Other studies analyzing the pa­tient perception of dialysis quality have also ob­tained similar results. [6] ,[19] Post-dialysis fatigue is a frequent complication that limits activity and quality of life among patients in the period im­mediately following the HD session. It is a poorly understood syndrome in which, the in­fluence of dialysate temperature has never been studied as a possible cause. [20] In our study, we found that post-dialysis fatigue syndrome is re­lated to dialysate temperature and reduction of the latter, decreases the perception of its se­verity and duration. It may not be true that all symptoms in all patients improve by decreasing the dialysate temperature. For instance, the inci­dence of cramps increases, as has been observed in a previous study. [22] We observed that the pa­tients benefiting with the use of low dialysate temperature are those who show poor tolerance with the usual dialysate temperature. Patients with more than one episode of hypotension per week and those with higher discomfort percep­tion during HD, or those with a more severe post-dialysis syndrome were the ones who be­nefited most with dialysate temperature of 35°C. In the remaining patients, no major change was observed in the analyzed parameters or the sub­jective perception of symptoms during HD with the use of cool dialysate.

Fine et al, [23] suggested the dialysate tempera­ture should be reduced only in patients whose body temperature was low, since they represent the group of patients who are likely to improve with this measure. In our study, the post dia­lysis body temperature was significantly lower in patients who were dialyzed with cool dia­lysate. Other studies have not been able to find such correlation between cool dialysate HD and body temperature. [12] Skin temperature does not help in identifying the group of patients that may benefit from reducing the dialysate temperature.

With the current available data, the role of dia­lysate temperature in HD is an issue that is not sufficiently explained. The rationale for using a dialysate temperature of 37°C is empirical and is based on the body temperature. This figure is being revised in the general population. [24] On the other hand, it is a well known fact that the tem­perature in dialysis patients is lower than that of the healthy population. [25] According to these data, the mean pre-dialysis axillary temperature during the first two weeks of our study were 36 and 36.1°C, respectively. These figures are lower than the mean values of 36.3°C reported in the literature for a healthy population. [24] Therefore, it is probably better to define the thermal as­pects of HD with regard to the physiologic ef­fects on the patient. During the HD session, there is an increase of heat production asso­ciated with a negative energy balance. [26] In order to achieve a neutral energy balance (thermoneu­tral dialysis), the body core temperature has to be raised using dialysate temperatures of about 37.5°C. Also, in order to keep the body core temperature steady (isothermal dialysis), it is required to increase energy loss by using dia­lysate with temperature of about 35.5°C or even lower, depending on the ultrafiltration rate. [14] ,[27] ,[28]

The increase in body core temperature is an important factor causing hemodynamic insta­bility and thus, isothermal dialysis is better tole­rated than thermoneutral dialysis. [27] Body core temperature, that of the blood coming out of the heart, is the one that controls the thermoregu­latory mechanisms. In recent clinical studies, tympanic temperature has been used as the reference method to measure core temperature in dialyzed patients. [12] ,[19] ,[23] ,[29] ,[30] In a preliminary study in our patients, we have noted that tym­panic temperature is 0.2-0.4°C higher than axil­lary temperature. In the present study, we used axillary temperature because it is the one usually measured in HD units. Moreover, although axil­lary temperature is lower than core temperature, the temperature of arterial blood reaching the dialyzer through an arteriovenous fistula is even lower. [25]

For measuring Kt/V and URR, the second­generation formula was used because, it elimi­nated the overestimation of Kt/V compared with the first formula. Also, the total error (absolute value percentage error + 0.02 SD) was reduced with the second-generation formula. The calcu­lation of the P-values shows that there were significant differences in the Kt/V eq values bet­ween dialysis with cool dialysate and standard dialysate. Contrary to earlier studies, [6] we found that cool dialysate had a beneficial effect on urea removal (P< 0.0001) and equilibrated Kt/V (P< 0.0001). Also, using of cool dialysate in this study resulted in achieving an increased ultra-filtration rate compared with normal dia­lysate (P< 0.0001).

   Conclusion Top

This study shows that cool dialysate improves tolerance to HD and is an important factor in stabilizing BP during HD, without compromi­sing the efficacy of dialysis. In general, this study also shows that usage of cool dialysate helps in achieving higher ultrafiltration while maintaining hemodynamic stability during and after dialysis. At the same time, the URR and Kt/V eq values were also increased. Using of cool dialysate is a simple, useful and economical procedure, especially for highly symptomatic patients. Not all patients may benefit from it and we should not forget that it creates a nega­tive energy balance, the clinical implication of which remains to be determined. Individualiza­tion of bath temperature by means of thermal sensors may be one of the clinical goals of HD in the years to come.

   Acknowledgement Top

The author thanks all medical staff at the nephrology department in the Ahmad Maher Teaching Hospital, Cairo, Egypt for their inva­luable support during the course of this study.

   References Top

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2.Lindholm T, Thysell H, Yamamato Y, Forsberg B, Gullberg C. Temperature and vascular stability in hemodialysis. Nephron 1985;39: 130-3.  Back to cited text no. 2    
3.Yu A, Ing T, Zabineh R, Daugirdas J. Effect of dialysate on central hemodynamic and urea kinetics. Kidney Int 1995;48:237-43.  Back to cited text no. 3    
4.Levin N, Morris A, Lavarias V, et al. Effect of body core temperature reduction on hemo­dynamic stability and hemodynamic efficiency at constant ultrafiltration. Nephrol Dial Transplant 1996;11:31-4.  Back to cited text no. 4    
5.Schneditz D. Temperature and thermal balance in hemodialysis. Semin Dial 2001;14:35-8.  Back to cited text no. 5    
6.Ayoub A, Finlayson M. Effect of cool tem­perature dialysate on the quality and patients' perception of hemodialysis. Nephrol Dial Transplant 2004;19(1):190-4.  Back to cited text no. 6    
7.Schneditz D, Martin K, Kramer M, Kenner T, Skrbal F. Effect of controlled extracorporeal blood cooling on ultrafiltration induced blood volume changes during hemodialysis. J Am Soc Nephrol 1997;8:956-64.  Back to cited text no. 7    
8.Maggiore Q, Pizzarelli F, Zoccali C, Sisca S, Nicolo F, Parlongo S. Effect of extracorporeal blood cooling on dialytic arterial hypotension. EDTA 1981;18:597-602.  Back to cited text no. 8    
9.Daugirdas JT. Dialysis hypotension: A hemo­dynamic analysis. Kidney Int 39:233-246, 1991.  Back to cited text no. 9    
10.Meada K, Morita H, Shinzato T, et al. Role of hypovolemia in dialysis induced hypotension. Artif Organs 1988;12:112-6  Back to cited text no. 10    
11.Jost C, Agarwal R, Kair El Din K, Grayburn P, Victor R, Henrich W. Effect of cooler tem­perature dialysate on hemodynamic stability in 'problem' dialysis patients. Kidney Int 1993; 39: 606-12.  Back to cited text no. 11    
12.Van der Sande FM, Kooman JP, Burema JH, et al. Effect of dialysate temperature on energy balance during hemodialysis: Quantification of energy transfer from the extracorporeal circuit to the patient. Am J Kidney Dis 1999;33:1115-21.  Back to cited text no. 12  [PUBMED]  [FULLTEXT]
13.Barendregt JN, Kooman JP, Van der San-de FM, et al. The effect of dialysate temperature on energy transfer during hemodialysis. Kidney Int 1999;55(6):2598-608.  Back to cited text no. 13    
14.Van der Sande FM, Gladziwa U, Kooman JP, Bocker G, Leunissen KM. Energy transfer is the single most important factor for the difference in vascular response between isolated ultrafil­tration and hemodialysis. J Am Soc Nephrol 2000;11;1512-7.  Back to cited text no. 14    
15.Lowrie EG, Lew NL. The urea reduction ratio (URR): a simple method for evaluating hemodia­lysis treatment. Contemp Dial Nephrol 1991;12: 11-20.  Back to cited text no. 15    
16.Daugirdas JT. Estimation of equilibrated Kt/V using the unequilibrated post dialysis BUN. Semin Dial 1995;8:283-4.  Back to cited text no. 16    
17.Daugirdas JT. Second generation logarithmic estimates of single-pool variable volume Kt/V: an analysis of error. J Am Soc Nephrol 1993;4 (5):1205-13.  Back to cited text no. 17    
18.K/DOQI Clinical Practice Guidelines for Cardiovascular Disease in Dialysis Patients: intradialytic hypotension. Am J Kidney Dis 2005;45(Suppl 3): S76-S80.  Back to cited text no. 18    
19.Cruz DN, Mahnensmith RL, Brickel HM, Perazella MA. Midodrine and cool dialysate are effective therapies for symptomatic intradialytic hypotension. Am J Kidney Dis 1999;33:920-6.  Back to cited text no. 19  [PUBMED]  [FULLTEXT]
20.Sklar A, Newman N, Scott R, Semenyuk L, Schultz J, Fiacco V. Identification of factors responsible for postdialysis fatigue. Am J Kidney Dis 1999;34:464-70.  Back to cited text no. 20  [PUBMED]  [FULLTEXT]
21.Hoeben H, Abu-Alfa AK, Mahnensmith R, Perazella MA. Hemodynamics in patients with intradialytic hypotension treated with cool dia­lysate or midodrine. Am J Kidney Dis 2002; 39:102-7.  Back to cited text no. 21  [PUBMED]  [FULLTEXT]
22.Marcen R, Quereda C, Orofino L, et al. Hemo­dialysis with low temperature dialysate: A long term experience. Nephron 1988;49:2932.  Back to cited text no. 22    
23.Fine A, Penner B. The protective effect of cool dialysate is dependent on patients' predialysis temperature. Am J Kidney Dis 1996;28:262-5.  Back to cited text no. 23  [PUBMED]  [FULLTEXT]
24.Sund-Levander M, Forsberg C, Wahren LK. Normal oral, rectal tympanic and axillary body temperature in adult men and women: a syste­matic literature review. Scand J Caring Sci 2002;16:122-8.  Back to cited text no. 24  [PUBMED]  [FULLTEXT]
25.Pergola PE, Habiba NM, Johnson JM. Body temperature regulation during hemodialysis in longterm patients: Is it time to change dialysate temperature prescripttion? Am J Kidney Dis 2004;44: 155-65.  Back to cited text no. 25    
26.Kaufman AM, Morris AT, Lavarias VA, et al. Effects of controlled blood cooling on hemo­dynamic stability and urea kinetics during high efficiency hemodialysis. J Am Soc Nephrol 1998;9:877-83.  Back to cited text no. 26  [PUBMED]  [FULLTEXT]
27.Maggiore Q. Isothermic dialysis for hypotension prone patients. Semin Dial 2002;15(3):187-90.  Back to cited text no. 27    
28.Rosales LM, Schneditz D, Morris AT, Rahmati S, Levin NW. Isothermic hemodialysis and ultra­filtration. Am J Kidney Dis 2000;36:353-61.  Back to cited text no. 28  [PUBMED]  [FULLTEXT]
29.Schneditz D, Rosales L, Kaufman AM, Kaysen G, Levin NW. Heat accumulation with relative blood volume decrease. Am J Kidney Dis 2002; 40:777-82.  Back to cited text no. 29  [PUBMED]  [FULLTEXT]
30.Keijman JM, Van der Sande FM, Kooman JP, Leunissen KM. Thermal energy balance and body temperature: comparison between isolated ultrafiltration and hemodialysis at different dialysate temperatures. Nephrol Dial Transplant 1999;14:2196-200.  Back to cited text no. 30  [PUBMED]  [FULLTEXT]

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