The effect of muscle relaxation on serum calcium and phosphorus levels in patients undergoing hemodialysis

El efecto de la relajación muscular en los niveles de calcio y fósforo en suero en pacientes sometidos a hemodiálisis

Zahra Mohammadi arashniya2012@yahoo.com

Babol University of Medical scienc, Irán

Fatemeh Biabani

, Tabriz University of Medical Sciences, Irán

This work is licensed under Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International.

End-Stage Renal Disease (ESRD) is an important health issue around the world¹. The number of patients with ESRD in the world by the end of 2011 was 2,786,000 that year, a 7.16% increase is witnessed where 2,164,000 are under treatment and 1,929,000 undergo dialysis2. Prevalence and incidence of ESRD in Iran are 357 and 57 per million per year, respectively³.

Dialysis is a stressful process and causes many psychological problems for patients. The inappropriate response of stresses decreases the life quality of these patients and causes many problems for them⁴.

High level of stress causes many consequences such as anxiety, depression, and physical and mental problems⁵. Moreover, increased heart rate, high blood pressure, secretion of cortisol hormones, epinephrine, and norepinephrine are the signs of mental pressures⁶. Cortisol is one of the important steroid hormones that regulate important body functions such as cardiovascular, metabolic, and immunological functions7. One of the important functions of this hormone is its effect on serum calcium levels. Cortisol, in addition to increasing calcium urinary excretion, decreases its intestinal absorption⁸. Hemodialysis patients have low calcium and high phosphorus levels: 1. Due to reduced glomerular filtration, phosphorus excretion in urine decreases and its level in blood increases; on the other hand, calcium reabsorption in tubules and blood decreases; 2. Due to digestive phosphorus excretion that is accompanied by calcium excretion, serum calcium level decreases.

Low calcium and high phosphorus levels in these patients lead to renal osteodystrophy. To correct calcium and phosphorus and treat this problem, drug therapies are used in hospitals¹⁰.

Due to the high costs and consequences of drug therapies for stress control and its consequences such as increased cortisol level and decreased calcium level, non-drug methods should be used to control stress and its consequences¹¹. Varied nursing measures function as non-drug and complementary treatment and relaxation are one of them^12,13. Relaxation, decreasing the sympathetic nervous system and decreasing secretion of catecholamine and cortisol leads to decreased muscle stress and undesirable effects of secreted cortisol and catecholamines due to stress¹⁴. Relaxation has different methods but the method proposed by Benson (1970) is more popular due to easy learning and training¹⁵.

According to the positive effects reported from the implementation of this technique, especially in decreasing stress level of hemodialysis patients¹⁶, positive effects reported regarding fatigue of hemodialysis patients¹⁷ and the effect of this technique on insomnia of these patients¹⁸, it is expected that according to the effect of this technique on decreasing the stress level of these patients¹⁶, it influences calcium and phosphorus levels of serum that is under the influence of catecholamines and stress hormones. Therefore, the present study aimed to investigate the effect of Benson's muscle relaxation response on serum calcium and phosphorus levels among hemodialysis patients.

Figura 1

This study is a randomized clinical trial and its population included all hemodialysis patients under hemodialysis treatment in Zahedan Hospital during 2013-2014. Subjects for control and test groups were selected equally. After the pilot study, subjects were assigned to test and control groups according to permutation blocks. Considering the confidence coefficient of 0.95 and test power of 80%, 45 subjects were estimated for each group that considering drop rate, 45 subjects for each group and in sum, 90 subjects for both groups were appointed (1 person excluded from the study due to death). Inclusion criteria included 18 to 65 years old patients, history of hemodialysis at least for two months, undergoing hemodialysis 2-3 times a week, having complete vigilance, acceptable oral and verbal abilities to learn relaxation method, no known psychological problem such as severe anxiety and depression, no history in muscle diseases, and having active file at the center of interest. Exclusion criteria included every condition that causes interference during the intervention and makes it impossible to continue the intervention such as mortality, travel, no interest for cooperation, and not attending the training sessions.

After selecting the subjects according to the inclusion criteria and receiving written consent, the subjects were randomly assigned into control and test groups based on the permutation blocks method. Instruments used in this study included demographic information questionnaire in two sections of personal information (e.g. gender, age, marital status, education, job) and information related to disease and treatment (e.g. history of blood pressure and diabetes, renal failure duration, hemodialysis, and number of dialysis sessions per week), checklist before recording calcium and phosphorus indices before and after the intervention, and relaxation recording form. Consistent with the research method, the patients were asked to complete demographic information questionnaire and phosphorus and calcium serum levels of all subjects were measured. Then, the muscle relaxation technique was trained individually in three sessions for the test group. After that, the patients performed the technique at home, 2 times per day for 30 days. The method was as follows: 1. The patient takes a comfortable position; 2. Closes the eyes; 3. Relaxes all muscles from feet gradually toward the face and keep calm; 4. Breathes from nose and awareness about it and exhales from the mouth gradually and repeats number 1 silently and breathes comfortably and normally; 5. Performs this task for 15-20 minutes while muscles are relaxed. Then, he opens the eyes and does not stand up for several minutes; 6. Do not worry about deep level of relaxation; let relaxation occur with its peace. When the disturbing thoughts came about, try to ignore them¹⁹. To ensure the implementation of the relaxation technique during the intervention period, give a checklist (relaxation recording form) to the subjects to record day, hour, relaxation duration, and its unsuccessful implementation. Moreover, an audiovisual file for relaxation training was given to the patients. Also, to solve the potential problems about the implementation of the technique during the study, the researcher, every day called the subjects and followed the procedure for the implementation of the technique and completing a relaxation recording form. Finally, after the intervention, laboratory indices of interest were studied in patients. To obtain a blood sample, after turning on the blood pump of the dialysis machine, blood was taken from the arterial side and immediately transferred to the laboratory. Samples were prepared in a certain type of test tube (serum tube) with 5 cc syringe and a certain type of kit (Pars Azmoon) was used for tests before and after the intervention.

For data analysis, data distribution in research groups was performed using the Kolmogorov-Smirnov test for normality. According to the normal distribution of data, an independent t-test was used to compare the mean of quantitative data and also to investigate the relationship between the qualitative variable, chi-square test at the significance level of 0>0.05 was used.

Findings: The findings showed that of all the sample studied (89), 52 were male and 37 were female and also showed that 68 were married and 21 were single. The average age of the sample was 43±15. Independent t-test did not show any significant difference between research groups in terms of age. Most of the sample were male, married, illiterate, and housewife. According to the chi-square test, research groups did not show any significant difference in terms of demographic variables of gender, marital status, education, and job and they were homogenous. Also, about information related to the disease, most of the units had a history of elevated blood pressure but did not show a history of diabetes. The chi-square test did not show any significant difference in terms of the mentioned variables and the groups were homogenous in this regard (Table 1).

Table 1. Frequency distribution of demographic characteristics and information related to research units’ diseases

Table 1
Frequency distribution of demographic characteristics and information related to research units’ diseases

Average calcium levels in the test group before and after the intervention were 8.69±1.18 and 8.79±0.95, respectively. According to the results of paired t-test in the test and control groups, no significant difference was observed before and after the intervention. Also, according to the results of the independent t-test, average calcium after the intervention was significantly higher in the test group (p-0.005). However, no significant difference existed before the intervention (p-0.2). Average phosphorus in the test group before the intervention was significantly higher than its value after the intervention (p-0.002, 4.76±1.58 vs 5.43±1.65) but no significant difference was observed in the control group before and after the intervention. The results of the independent t-test showed that average phosphorus did not show any significant difference before and after the intervention (Table 2).

Table 2. Comparison of the mean and standard deviation of calcium and phosphorus before and after the intervention for each group

Table 2.
Comparison of the mean and standard deviation of calcium and phosphorus before and after the intervention for each group

The results of the Pearson correlation coefficient showed that no significant relationship exists between calcium and phosphorus before and after the intervention (p>0.05). The results of Table 3 showed that a significant relationship exists between average serum calcium before and after the intervention and job status of people. The results of Tukey's post hoc test showed that average calcium in employees before and after the intervention is significantly higher than housewife subjects (p-0.01). Also, no significant relationship exists between calcium levels before and after the intervention and gender and education. The results of Table 4 showed that no relationship exists between average phosphorus levels before and after the intervention and gender, education, and job status.

Table 3. The relationship between average serum calcium and demographic variables before and after the intervention

Table 3
The relationship between average serum calcium and demographic variables before and after the intervention

Table 4. The relationship between average serum phosphorus and demographic variables before and after the intervention

Table 4.
The relationship between average serum phosphorus and demographic variables before and after the intervention

In this study, the effect of muscle relaxation based on Benson’s muscle relaxation response on serum calcium and phosphorus levels of hemodialysis patients was investigated. The results showed that this technique increases serum sodium level in the test group while no significant effect was observed on serum phosphorus level of these patients.

Searching in authoritative research databases did not find any study on the effect of relaxation techniques on serum indices of patients. The findings were related to the effect of diet training on the levels of certain serum indices of hemodialysis patients. The results of studies by Salehi²⁰ and Baraz showed that average calcium for three months after diet training for hemodialysis patients did not show any significant increase while the results of a study by Schalatter showed that calcium level after training increased significantly. Ebrahimi and Sadeghi also showed that diet training has a significant effect on increased serum calcium among hemodialysis patients.

Muscle relaxation influences the sympathetic system and decreases catecholamine secretions that lead to decreased cortisol secretion and increased calcium serum level in the body.

The results of the present study did not show any significant effect of relaxation on the phosphorus serum level in the test group. The results of studies by Salehi et al., Ebrahimi and Sadeghi, and Oka et al. showed a significant decrease in phosphorus level among hemodialysis patients after diet training.

Also, the results showed that there is no significant relationship between age, gender, and education of subjects with calcium and phosphorus levels (before and after the intervention). However, average calcium in employees is significantly higher than housewives after the intervention (p-0.01). It seems that increased serum calcium level that is observed both before and after the intervention, is related to the diet of these patients due to better financial level and following a particular diet compared with housewives.

Since this technique did not significantly decrease the phosphorus level, it is recommended to investigate the effect of other non-drug techniques and methods on the serum phosphorus level of these patients.

Due to the low cost and non-drug nature of Branson's muscle relaxation and positive effects on serum calcium level due to decreased adrenaline and catecholamine secretions, it is recommended to train this technique in hemodialysis units.

Acknowledgment: This article is the result of a thesis to receive a Master's Degree in Critical Care Nursing with the ethics code of recGMU/1392/43 and the Center for Clinical Trials Registration's code of IRCT2014051117656N1. The authors appreciate the Graduate Council and Research Council of Gonabad University of Medical Sciences. Also, the authors appreciate the sincere cooperation of staff and hemodialysis patients of 22 Bahman Hospital of Gonabad, Khatamolanbia Hospital, and Emam Ali Hospital and special thanks to Mrs. Nikpour, Mrs. Khaghani, Mrs. Nikbakht, Mrs. Maghsoodpour, Mr. Mohammadi, and Mr. Rafi.