Lin-Fang Xu,Chun-Lei Wu,Hong-Mei Sun,Tong-Qiang Liu

Yanghu Branch,Changzhou No.2 People's Hospital,Changzhou,Jiangsu 213164,China

Original Article

Exploration of a reasonable dialysate temperature setting in hemodialysis for patients with hypertension

Lin-Fang Xu,Chun-Lei Wu*,Hong-Mei Sun,Tong-Qiang Liu

Yanghu Branch,Changzhou No.2 People's Hospital,Changzhou,Jiangsu 213164,China

A R T I C L E I N F O

Article history:

Received 15 May 2015

Received in revised form

15 December 2015

Accepted 17 June 2016

Available online 15 September 2016

Hemodialysis

Hypertension

Dialysate

Temperature

Blood pressure

Objective:This study aims to investigate the effect of 4 different dialysate temperatures on blood pressure during hemodialysis for patients with hypertension.

Methods:Using a self-controlled method,the patients'body temperature was set as T.Accordingly,the dialysate temperature was set as 37°C,T+0.5°C,T,and T-0.5°C.The changes in blood pressure,heart rate,mean arterial pressure and dialysis-induced adverse reactions at the 4 different dialysate temperatures were consistently monitored.

Results:Patients who received hemodialysis with 37°C and T+0.5°C dialysate demonstrated an unstable blood pressure and a higher incidence of adverse reactions.Patients who received hemodialysis with T and T-0.5°C dialysate showed a relatively stable blood pressure,heart rate,and mean arterial pressure during dialysis.In particular,dialysate at T-0.5°C resulted in the most stable blood pressure, the fewest adverse reactions and the best self-assessed comfort scores(P＜0.01).

Conclusions:The dialysate temperature during hemodialysis for patients with hypertension should be set to a temperature based on patients'preoperative body temperate T or 0.5°C below T.This practice is suggested to enhance the stability of patients'blood pressure and heart rate during hemodialysis,reduce complications and improve patients'tolerance of hemodialysis.

©2016 Shanxi Medical Periodical Press.Publishing services by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

1.Introduction

In clinical work,the prevention and treatment of dialysisinduced hypotension is typically timely and effective,but the treatment of hypertension during dialysis is often ineffective,and dialysis physicians even feel helpless in some intractable cases. Hypertension in dialysis patients often manifests as flushing, headache,hot flashes,vomiting,heavy sweating and other discomforts.Conventionally,decreasing the conductivity and blood flow or the oral administration of antihypertensive drugs is used to prevent and treat hypertension,but these interventions may not result in a noticeable or stable response.Patients'blood pressures often return to the original level or even higher soon after a shortterm reduction following treatment.The blood pressure eventually falls back to normal levels by different post-dialysis time periods.In addition,high blood pressure during dialysis causes fear,stress, anxiety,and depression in patients and reduces their quality of life.It is also a safety risk during the dialysis session.In this study,we used dialysates at 4 different temperatures in patients with hypertension during dialysis to explore the best dialysate temperature to reduce blood pressure changes and the incidence of adverse reactions during dialysis.

2.Subjects and methods

2.1.Subjects

Twenty dialysis patients with hypertension in the hemodialysis center at our hospital from January to December 2014 were selected for this study.The inclusion criteria were as follows:(1) adequate dialysis had been performed for more than 6 months; (2)blood pressure gradually increased during the process of dialysis,and the mean arterial pressure increased by 15 mmHg (1 mmHg=0.133 kPa)or more compared with the level recorded before dialysis.1The exclusion criteria included the following:(1) the hypertension occurred before dialysis,but the blood pressure gradually decreased to normal during the process of dialysis;(2) the blood pressure during dialysis was dangerously high,with thesystolic blood pressure equal to or exceeding 200 mmHg;(3)the patient had recently experienced a fever or had a history of infection,acute cardiovascular or cerebrovascular disease,or hyperthyroidism;and(4)the patient refused to cooperate.All of the enrolled patients signed the written informed consent.There were 10 males and 10 females aged between 42 and 67 years (52.3±6.7)years with a dialysis duration of 8 months to 65 months(18.1±16.5)months and an average blood pressure of (155.8±11.9)/(90.9±11.2)mmHg.Their underlying renal diseases included 6 cases of chronic glomerulonephritis,8 cases of diabetic nephropathy,5 cases of hypertensive nephropathy,and 1 case of lupus nephritis.

2.2.Methods

2.2.1.Intervention methods

An F6HPS polysulfone dialyzer was used for the dialysis(4 h per treatment,three times per week for each patient).The blood flow ratewas set at 200-250 mL/min,and the dialysateflowratewas set at 500 mL/min.The bicarbonate dialysate used comprised various concentrations of ions:HCO-3at 32 mmol/L,Na+at 138 mmol/L,K+at 2.0 mmol/L,Ca2+at 1.25 mmol/L,Mg2+at 0.5 mmol/L,Cl-at 108 mmol/L and CH3COO-at 3.0 mmol/L.The electrical conductivity was set to 138 ms/cm.Conventional heparin or low-molecularweight heparin was used for anticoagulation.Before the study was started,all of the patients had their body weight under control, and their average dry body weight was 52.2±13.4 kg.The ultrafiltration volume was 2.3±1.2 kg per dialysis treatment.The antihypertensive and dialysis treatment options were kept at the same for all patients.Patients'oral temperature was measured for 5 min with a mercury thermometer immediately before starting dialysis.

Previous studies have shown that an elevated dialysate temperature can increase the blood temperature,thus decreasing blood pressure.2In contrast,our previous research results also indicated that extremely high dialysate temperatures could cause a higher incidence of headaches,hot flashes,heart palpitations,chest tightness,nausea,vomiting and other adverse reactions,while extremely low dialysate temperatures could increase blood pressure in dialysis patients.3Therefore,in this study,we excluded interference from extremely high and low temperatures.We measured patients'pre-dialysis body temperature,denoted as T, and carried out our experiment on patients using dialysate at four different temperatures:(1)37°C,as the default standard dialysate temperature parameter of the dialysis machine;(2)T+0.5°C,0.5°C higher than the measured body temperature(T),on average 37.2±0.7°C;(3)T,the measured body temperature,on average 36.8±0.4°C;and(4)T-0.5°C,0.5°C lower than the measured body temperature,on average 36.1±0.7°C.Each patient was dialyzed for 4 weeks at each temperature,3 times per week.The ambient temperature in the hemodialysis center was 22°C-24°C, and the humidity was maintained at 50%-60%.

2.2.2.Measurement criteria

(1)The hourly changes in blood pressure,heart rate and mean arterial pressure during dialysis were monitored.(2)The frequency of adverse reactions,such as headaches,hot flashes,palpitations and dyspnea,nausea and vomiting,sweating,and chills was observed and recorded for the dialysis patients.(3)The number of early dialysis session terminations was recorded.(4)The frequency of administering antihypertensive drug was recorded.During dialysis,if the systolicblood pressurewas higher than180 mmHgor if the diastolic blood pressure was higher than100 mmHg,patients were given antihypertensive drugs.(5)Patient comfort scores were assessed using a visual analog scale over a 10-point range4and were given by the dialysis patients according to their own subjective feeling.On this scale,0-2 points represents comfortable,3-4 represents mild discomfort,5-6 represents moderate discomfort, 7-8 represents discomfortand 9-10 represents extreme discomfort.

2.2.3.Statistical analysis

SPSS17.0 software was used for statistical analysis.Measurements were represented as the mean±standard deviation(x-±s). Categorical data were expressed in percentages.An F test was used for intergroup comparison.Theχ2test was applied to compare percentage data.The difference was considered statistically significant when P＜0.05.

3.Results

3.1.Changes in blood pressure,heart rate and mean arterial

pressure in patients at 4 different dialysate temperatures

Application of 37°C and T+0.5°C dialysate resulted in significant changes in blood pressure,heart rate and mean arterial pressure(P＜0.05)in dialysis patients.However,no significant changes in the patients'blood pressure,heart rate,or mean arterial pressure (P＞0.05)were observed in dialysis processes at T and T-0.5.In particular,T-0.5°C resulted in the most stable measurement outcomes as shown in Table 1 and Table 2.

3.2.Comparison of adverse reactions and patient's comfort score among dialysis patients at 4 different dialysate temperatures

Patients treated with dialysate at 37°C and T+0.5°C showed relatively higher incidence rates of adverse reactions and the need for the administration of antihypertensive drugs.In contrast,patients treated with dialysate at T and T-0.5°C showed lower incidence rates of adverse reactions and the need for the administration of antihypertensive drugs.In particular,patients receiving dialysate at T-0.5°C showed the best comfort rating outcomes (lowest scores,P＜0.01).No statistically significant difference (P＞0.05)was observed for the rate of early termination of dialysis between groups as shown in Table 3.

4.Discussions

4.1.Incidence and risk of hypertension in hemodialysis patients

Nearly 80%of maintenance hemodialysis patients have hypertension.5The majority of hypertensive patients in hemodialysis receive antihypertensive drug treatment,but only 30%achieve good control of their blood pressure.Some patients in dialysis show an increase rather than a decrease in their blood pressure.6,7Severe hypertension and the use of anticoagulants are risk factors for cardiovascular and cerebrovascular diseases in patients,potentially causing serious impacts on quality of life and patient safety. Therefore,it is important to prevent and control hypertension during dialysis.

4.2.Effect of dialysate temperature on blood pressure in hemodialysis patients

Human blood pressure regulatory pathways involve sympathetic regulation,the renin-angiotensin-aldosterone system,regulation of cardiac output and peripheral vascular tension,etc.8Therefore,adjustment of the dialysate temperature as a means to regulate patients'body temperature and blood pressure and to balance patients'body energy was explored in this study.9Someresearchers have suggested that tolerance of dialysate temperature differences is correlated with the pre-dialysis body temperature.10Some studies have also confirmed that a high dialysate temperature can increase blood temperature,decrease blood pressure and cause fever,tachycardia,nausea,vomiting and other symptoms.2In this study,the dialysate temperatures were selected based on the pre-dialysis measured body temperature,T.At the standard dialysate temperature 37°C and T+0.5°C,the majority of patients showed an increase rather than a decrease in blood pressure.Some patients experienced headache,irritability,heavy sweating,nausea, vomiting and other symptoms.In addition,2 patients complained of severe headache and dizziness and requested early termination of the dialysis session.For patients with dialysates at T and T-0.5°C,and especially for patients with dialysate at T,their heart rates were stable,and their blood pressure(i.e.,their mean arterial pressure)showed only a slight increase,which was not statistically significant(P＞0.05).In addition,adverse reactions were less common in these patients,and only 2 patients undergoing dialysis with dialysate at these temperatures showed minor chills but were able to finish the entire course of dialysis.In this study,patients undergoing dialysis with dialysate at 37°C and T+0.5°C did not show any decrease in blood pressure with the increase in dialysate temperature.Patients undergoing dialysis with dialysate at T and T-0.5°C exhibited relatively stable blood pressures,which may be attributable to the controlled average heart rate during hemodialysis.11Patients undergoing dialysiswith dialysates at Tand T-0.5°C could avoid the restlessness and heavy sweating caused by higher dialysate temperatures and the inaccurate ultrafiltration volumes generated by a subsequent early termination of dialysis.This practice increased patient tolerance during dialysis treatment.At the same time,patients undergoing dialysis with dialysates at Tand T-0.5°C experienced a smooth process without headache or other adverse reactions,which may be related to the avoidance of increased sympathetic activity due to increased body temperature, which is in agreement with the study by Zhang et al.12

Table 1Changes in blood pressure in patients at 4 different dialysate temperatures(x-±s)/mmHg.

Table 2Changes in heart rate and mean arterial pressure in patients at 4 different dialysate temperatures(x-±s).

Table 3Comparison of adverse reactions in dialysis patients at 4 different temperatures.(n=20).

4.3.The significance of a reasonable setting for dialysate temperature on control of blood pressure during hemodialysis

During hemodialysis,a too high,too low or highly fluctuant blood pressure will affect the blood supply to vital organs and can even endanger patients'lives.Therefore,maintaining a stable blood pressure and heart rate during the process of dialysis has a very high clinical importance.In this study on patients with hypertension,an appropriate reduction in the dialysate temperature based on the measured pre-dialysis body temperature(T-0.5°C)not only stabilized blood pressures but effectively reduced the occurrence of complications during dialysis and improved dialysis tolerance and the accuracy of ultrafiltration,achieving better dialysis outcomes. This practice is worth promoting in clinical application.The best reasonable selection of dialysate temperature should be adjusted according to individual differences in patients.

Conflicts of interest

All contributing authors declare no conflicts of interest.

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How to cite this article:Xu L-F,Wu C-L,Sun H-M,et al.Exploration of a reasonable dialysate temperature setting in hemodialysis for patients with hypertension.Chin Nurs Res.2016;3:133-136. http://dx.doi.org/10.1016/j.cnre.2016.06.017

*Corresponding author.

E-mail address:406598905@qq.com(C.-L.Wu).

Peer review under responsibility of Shanxi Medical Periodical Press.

http://dx.doi.org/10.1016/j.cnre.2016.06.017

2095-7718/©2016 Shanxi Medical Periodical Press.Publishing services by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons. org/licenses/by-nc-nd/4.0/).