Effect of thermal therapy using hot water bottles on brain natriuretic peptide in chronic hemodialysis patients

doi:10.4236/health.2013.52034

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Vol.5, No.2, 253-258 (2013) Health

http://dx.doi.org/10.4236/health.2013.52034

Effect of thermal therapy using hot water bottles on

brain natriuretic peptide in chronic hemodialysis

patients

Yoko Uchiyama-Tanaka*

Yoko Clinic, Kitakyushu, Japan; [email protected]

Received 14 May 2011; revised 15 August 2012; accepted 28 August 2012

ABSTRACT

Introduction: The use of repeated thermal the-

rapy for improving the symptoms of chronic

heart failure (CHF) has been recently demon-

strated. Usually, thermal therapy requires an in-

frared dry sauna. However, it is difficult for small

clinics to acquire such an expensive and exten-

sive sy stem. The author assessed the efficacy of

its substitution with hot water bottles. Moreover,

there are no prior studies demonstrating the

efficacy of thermal therapy in hemodialysis pa-

tients with chronic heart failure. Methods: The

author evaluated plasma brain natriuretic pep-

tide (BNP) levels in 98 hemodialysis p atients in a

clinic. A total of nine patients w hose BNP levels

were more than 500 pg/mL agreed to be enrolled

in this study and received thermal therapy using

hot water bottles. Results: Plasma BNP levels, a

potential marker for CHF, tended to decrease

(891 ± 448 pg/mL to 680 ± 339 pg/mL), but the

difference was not significant (P = 0.0845). The

oral temperature changed from 36.44˚C ± 0.45˚C

to 37.04˚C ± 0.48˚C (+0.597˚C, P < 0.0001). No

side effect s were experie nced during the t herapy.

Moreover, most patients had an improvement in

their symptoms and the ability to perform activi-

ties of daily living. Conclusion: Thermal therapy

using hot water bottles is very safe and tends to

reduce plasma BNP levels in hemodialysis pa-

tient s with CHF.

Keyw ords: BNP; Brain Natriure t i c Pe p t i de; Chronic

Heart Failure; Chronic Kidney Disease;

Hemodialysis; Hot Water Bottle Thermal Therapy

1. INTRODUCTION

Chronic heart failure (CHF) is a major serious com-

plication for hemodialysis patients [1-3]. Kihara et al.

and Miyata et al. recently reported that repeated thermal

therapy could improve hemodynamics and symptoms in

patients with CFH [4-6]. The therapy requires an infra-

red-ray dry sauna because the temperature needs to be

maintained evenly at 60˚C. Unfortunately, it is difficult

for small clinics to acquire such an expensive and exten-

sive system. Tei et al. [4-6] proposed warm water baths

as a substitute for saunas, which can warm the body

without overloading the heart.

This study assessed whether thermal therapy for CHF

using hot water bottles can be used as a substitute for

infrared-ray dry sauna. Moreover, the author also as-

sessed whether thermal therapy is useful for hemodialy-

sis patients with CHF as there have been no studies

demonstrating the efficacy of thermal therapy in this

patient population. BNP is a superior parameter for as-

sessing left ventricular (LV) function rather than volume

overload of heart failure patients with normal kidney

function [7]. Hemodialysis patients are loading of vo-

lume every day. This study used BNP as parameter for

assessing LV function.

2. MATERIALS AND METHODS

2.1. Study Design and Participants

The study procedures were in accordance with the

guidelines of the 2000 Declaration of Helsinki for human

experimentation. All subjects provided informed consent.

Nine out of 98 inpatients undergoing hemodialysis treat-

ment in November 2007 at the Hosoe clinic, and whose

BNP levels were more than 500 pg/mL were enrolled in

this study. Patients with arterial ventricular stenosis and

other outflow obstacle heart disease were excluded, as

such thermal therapy is contraindicated in these condi-

tions [4,5]. None of the nine patients had any signs,

symptoms, or history of cancer or any active inflamma-

tory disease.

2.2. Laboratory Measurements

To evaluate brain natriuretic peptide (BNP) levels after

*The author declares no conflict of interest.

Y. Uchiyama-Tanaka / Health 5 (2013) 253-258

254

hemodialysis, blood samples of the patients were col-

lected in the supine position. Plasma samples were pre-

pared within 30 minutes after collection using a pre-

cooled centrifuge. Extracted plasma samples were frozen

immediately and stored at −20˚C until analysis. Plasma

BNP concentrations were measured by an immunoradi-

ometric assay specific for human BNP using a commer-

cial kit (Shionogi BNP kit; Shionogi Co. Ltd., Osaka,

Japan). The author again collected blood samples 3

months later at the end of the follow-up period. Oral

temperature was measured before and after each therapy

session.

2.3. Thermotherapy Using Hot Water Bottles

The author interviewed and evaluated the ability to

perform activities of daily living (ADL), and classified

the heart failure using the classification of New York

Heart Association (NYHA) before and after this study.

Before this study, all patients were treated with beta-

blockers, angiotensin II-converting enzyme inhibitors,

and angiotensin II-receptor blockers according to the

treatment guideline for the evaluation and management

of CHF [8]. Drug treatment was continued throughout

the study. After an examination that involved measuring

patients’ dry weight, and assessing X-ray images and

other clinical parameters, such as blood pressure, patients

received thermal therapy using hot water bottles. This

therapy is derived from the thermal therapy using an in-

frared-ray dry sauna invented by Kihara et al. and Mi-

yata et al. [4,5]. Initially, patients received a hot water

foot bath (44˚C) for 30 minutes. Subsequently, patients

were then asked to lie down on a bed with hot water bot-

tles and were wrapped in a blanket for another 30 min-

utes. This procedure was repeated three times per week

after hemodialysis for a total follow-up period of 3

months.

2.4. Statistical Analysis

Values are expressed as the mean ± SD. Student’s

t-test was used for all comparisons. P-values less than

0.05 were considered significant.

3. RESULTS

Demographic and clinical characteristics of the pa-

tients are summarized in Tables 1 and 2, respectively.

Before the study, the author assessed the ability of pa-

tients to perform ADL. If, despite high BNP levels, the

patients did not complain of NYHA-defined heart fail-

ure-related symptoms, it was speculated that it might

have been difficult for hemodialysis patients with many

other aches and joint problems to notice the symptoms

related to heart failure. Each patient underwent the ther-

mal therapy three times per week after hemodialysis for

3 months. The nine patients who were included in the

analysis (two men and seven women; mean age, 74.2 ±

14.6 years old; average duration of hemodialysis, 8.3 ±

6.2 years) were able to continue thermotherapy and were

observed for 3 months. Plasma BNP levels in the periph-

eral blood changed from 891 ± 448 pg/mL (range 419 -

1627 pg/mL) to 680 ± 339 pg/mL (range 208 - 1100

pg/mL) after 3 months (P = 0.0845). The change in

plasma BNP levels was not significant, but the levels

tended to decrease. The oral temperature changed from

36.44˚C ± 0.45˚C to 37.04˚C ± 0.48˚C (+0.597˚C, P <

0.0001). After 3 months of thermal therapy, the ADL

score was improved in all patients (Table 2).

Other clinical parameters, such as blood pressure, dry

weight, anemia, and cardiothoracic ratio did not change

significantly (data not shown). Results of the echocar-

diogram tests conducted before and after the study period

revealed no significant change in the ejection fraction

and other associated parameters (data not shown). No

side effects were experienced during the therapy.

Table 1. Demographic characteristics, and present heart disease and other conditions of the study population.

Case Age (years) Sex Duration of hemodialysis (years) Heart disease

1 79 Female 5.0 SN/AR moderate

2 79 Male 6.0 CGN/MR mild

3 53 Female 15.0 DM/LVH

4 83 Female 3.0 DM/OMI

5 73 Female 13.0 PKD/MR and LVH mild

6 80 Female 5.0 DM/MR and AR

7 47 Male 6.0 SN/MR

8 90 Female 2.0 MR/AR and LVH

9 84 Female 20.0 PKD/MR

AF atrial fibrillation, AR aortic valve regurgitation, CGN chronic glomerular nephropathy, DM diabetic nephropathy, LV H left ventricular hypertrophy, MR

mitral valve regurgitation, OMI old myocardial infarction, PKD polycystic kidney disease, SN sclerosis nephropathy.

Y. Uchiyama-Tanaka / Health 5 (2013) 253-258 255

Table 2. Demographic characteristics of the study population and the experienced symptom change.

Case Age

(years) Sex Ability to perform ADL† Change in ability to perform ADL NYHA heart failure

classification change

1 79 Female Pain in the right knee* Disappeared II → I

2 79 Male No symptoms No change II → I

3 53 Female Chill, heart palpitation at rest Disappeared (both symptoms) II → I

4 83 Female No symptoms No change I → I

5 73 Female

Right hand sclerosis (10/10); abdominal

pain after abdominal surgery (10/10); pain

in the left knee (10/10); could not perform

housework

Improvement in hand movement

(6/10), abdominal pain (3/10), knee

pain (5/10); could perform some

housework‡

6 80 Female Back pain Disappeared§ NA

7 47 Male Could not speak after brain hemorrhage Became more alert and started

speaking¶ NA

8 90 Female Pain in both knees Disappeared** NA

9 84 Female Pain in the left shoulder, toothache Disappeared†† NA

ADL activities of daily living, NYHA New York Heart Association. *The duration of knee pain was over a year; †Symptoms were assessed on a scale from 1

(minimal) - 10 (maximum); ‡The patient could not walk for 100 meters because of knee pain; after the study the patient could walk 3 km; §The patient could not

walk and used a wheelchair; after the study the patient could walk with a cane; ¶The patient could not speak to complain of any symptoms for 5 years, after the

study the patient could speak; **The patient could not walk because of knee pain and used a wheelchair; after the study the patient can walk with a cane; ††The

patient is bedridden.

4. DISCUSSION

Results of this study suggest that the ability to perform

ADL of hemodialysis patients can be improved with the

use of hot water bottle thermal therapy, and that such

therapy can help to decrease plasma BNP levels. This is

the first study to demonstrate that mild thermal therapy is

an effective, relatively safe, and easy way to improve the

ability to perform ADL, and may also improve LV func-

tion in CHF patients.

Thermal therapy, also known as Waon therapy, is de-

fined as “therapy in which the entire body is warmed in

an evenly heated chamber for 15 min at a temperature

that soothes the mind and body, and after the deep body

has increased by approximately 1.0˚C - 1.2˚C, the sooth-

ing warmth continues at rest for an additional 30 min,

with fluids supplied at the end to replace the loss from

perspiration” [4].

According to Tei [4-6], although medical progress in

the 20th century has been outstanding, there is still no

way of determining the magnitude of a patient’s internal

suffering and conflict. Medical staff cannot understand

the extent of pain, tension, and stress experienced by

patients who receive life-saving therapies, especially

CHF patients ineligible for operation. Kihara et al. and

Miyata et al. developed thermal therapy for such patients,

and it has been found to improve hemodynamics and

decrease serum BNP levels, arrhythmia, and sympathetic

nervous system activity, which occurs with severe car-

diac failure [4-6]. Moreover, this method is an effective

treatment for Sjogren disease and other lifestyle-related

diseases, such as hypertension, diabetes mellitus, hyper-

lipidemia, obesity, and smoking-related diseases [9,10].

Warming the body has been shown to relieve the

sympathetic nervous system [5-7]. Furthermore, it has

been shown that it might also improve the immune sys-

tem [11-13]. Warming the body using hot water bottles

warms the patient slowly and does not burden weak pa-

tients [11]. In the current medical practice, the medical

staff often does not have the sufficient time to see and

talk to patients. Talking and listening to a suffering pa-

tient enables them to relax and develop a trusting rela-

tionship with the medical team. The time spent with the

patient by the medical staff during the thermal treatment

might be the most important and effective part of this

therapy.

In the present study, most patients reported alleviation

of pain and the symptoms impacting the ability to per-

form ADL during the thermal therapy. Warming de-

creases activity of the sympathetic nervous system and

opens peripheral blood vessels, resulting in relaxation of

tendons and muscles [4-6]. Reducing the pain also de-

creases activity of the sympathetic nervous system and

increases the patient’s trust in the medical staff, resulting

in more efficient medical care.

There are no previous studies on the appropriate dura-

tion of the thermal treatment. The effect of sauna therapy

after 2 - 4 weeks has been reported [4-6], and the authors

suggest that the therapy was effective for improving the

ability to perform ADL in severe heart failure patients

when performed once a day for 3 - 4 days a week. In

addition, this method is very easy to implement; hence,

the length of each session can vary as required.

Measuring BNP levels is the established parameter for

assessing LV function with normal kidney function [7].

However, there are conflicting results concerning as-

Y. Uchiyama-Tanaka / Health 5 (2013) 253-258

256

sessing chronic renal function, especially in dialysis pa-

tients. Many reports recommend using the BNP level as a

possible prognostic marker for cardiac disease even in

chronic kidney disease (CKD) [14-17]. Park et al. re-

cently reported that the BNP level is a useful marker for

assessing the risk of new cardiac events in patients with

CKD [18]. There are few reports recommending BNP

levels as a prognostic marker for CHF in CKD because

BNP levels in hemodialysis patients vary within a large

range. Moreover, the level of BNP in hemodialysis pa-

tients can change daily [14,19]. Although a few reports

suggest that the normal BNP level is below 100 pg/dL

even in hemodialysis patients [20], other reports most

commonly suggest a range of 150 - 300 pg/dL for pa-

tients without heart disease, but this level is not consis-

tently reported and is based on cross-sectional studies

[21,22].

There have been no reports on longitudinal BNP levels

in hemodialysis patients. In the present study, the author

evaluated BNP levels in hemodialysis patients by means

of a longitudinal study. In most people without CKD,

BNP enhanced LV systolic and diastolic functions. How-

ever, the most precise and convenient method for the

evaluation of diastolic LV function remains controversial.

It is difficult to evaluate diastolic LV function by general

ultrasonography [23]. Echocardiography was performed

for all patients in the present study, but patients’ ability to

perform ADL was very poor and correct posture could

not be obtained. Some patients also had lung disease

with severe calcifications. Among patients on hemodi-

alysis, there are numerous patients with normal ejection

fraction, who also have restricted function of left ventri-

cle because of chronic volume overload, volume change,

hypertension, and/or amyloidosis.

The timing for measuring the BNP level is very im-

portant. In the present study, the author compared BNP

levels in the same patients at different times. Before

hemodialysis, weight gain (water volume) values dif-

fered each time, but after hemodialysis, dry weight va-

lues were fixed for each patient. The BNP level was

found to have less of a relationship to water volume, but

the levels were measured before and after hemodialysis,

and were clearly different. The author evaluated the BNP

levels after hemodialysis. This might be the reason that

there was no significant change in BNP levels before and

after the study. Interestingly, the BNP level could be used

as a marker for LV function in some patients, as shown

in the two patients whose BNP levels clearly decreased

in the present study (Figure 1). However, there is no

consensus on the best time to measure the BNP levels in

hemodialysis patients, whether it is at the start or end of

the week, or pre- or post-hemodialysis. The author de-

cided to measure BNP levels after hemodialysis when

weights were fixed and other parameters were stable. It

was difficult to find the most convenient and valid pa-

rameter to determine heart function in hemodialysis pa-

tients. BNP levels decreased in this study, but the de-

crease was not statistically significant; however, some

patients experienced significant decreases in BNP (Fig-

ure 1).

There were several limitations to this study. The num-

ber of patients was very limited and the increase of body

Figure 1. BNP levels before and after the present study of the two patients whose BNP clearly decreased. BNP brain

natriuretic peptide.

Y. Uchiyama-Tanaka / Health 5 (2013) 253-258 257

temperature in the study was 0.597˚C, less than 1.0˚C

suggested by Tei’s et al. Furthermore, the renal impair-

ment of hemodialysis patients in the present study may

lead to accumulation of levels of N-terminal proBNP [7,

15,24,25]. Moreover, this study included a small popula-

tion that was followed up for a very limited duration.

5. CONCLUSION

Using such a convenient and simple method for ther-

mal therapy, the author demonstrated an improvement in

patients who suffered from pain and experienced diffi-

culty with mobility. The therapy also could be conducted

without the side effects associated with other effective

therapies. The author concludes that thermal therapy

using hot water bottles is very safe and tends to decrease

plasma BNP levels in hemodialysis patients with CHF.

6. KEY SUMMARY POINTS

 The author assessed the efficacy of substituting infra-

red dry sauna with hot water bottle thermal therapy.

 A total of nine patients whose brain natriuretic pep-

tide (BNP) levels were more than 500 pg/mL agreed

to be enrolled in this study and received thermal

therapy using hot water bottles.

 Plasma BNP levels tends to decrease (891 ± 448

pg/mL to 680 ± 339 pg/mL), but there was no signi-

ficant difference (P = 0.0845). The oral temperature

changed 36.44˚C ± 0.45˚C to 37.04˚C ± 0.48˚C

(+0.597˚C, P < 0.0001).

 Most patients showed an improvement in their symp-

toms and ability to perform activities of daily living.

 The author concludes that thermal therapy using hot

water bottle is a very safe and tends to reduce plasma

BNP levels in hemodialysis patients with chronic

heart failure.

7. ACKNOWLEDGMENTS

Dr. Uchiyama-Tanaka is the guarantor for this article, and takes re-

sponsibility for the integrity of the work as a whole.

Open Access. This article is distributed under the terms of the Crea-

tive Commons Attribution Noncommercial License which permits any

noncommercial use, distribution, and reproduction in any medium,

provided the original author(s) and source are credited.

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