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Isothermal dialysis to control intradialytic hypotension and patient comfort: a pilot study.

Intradialytic hypotension (IDH) is a common complication of hemodialysis (HD). IDH can limit removal of metabolic waste products and extra fluid volume, which reduces the effectiveness or adequacy of the treatment. Patients may experience post-treatment symptoms, such as respiratory distress resulting from unresolved hypervolemia or malaise from persistent uremia.

IDH is multifactorial. It is related to a complex cascade of events resulting in low blood pressure, decreased circulating blood volume, cardiac decompensation, and an inadequate vascular response to the treatment (van der Sande et al., 2009). Several methods can be used to control IDH.

Reducing the dialysate temperature is a simple and cost-effective method of controlling IDH (Azar, 2009; Pizzarelli, 2007; Ramos et al., 2007; Selby & McIntyre, 2006). The majority of studies of thermal control are specific to the outpatient HD population (Azar, 2009; Ghasemi, Shafiee, & Rowghani, 2008; Ramos et al., 2007), in which only narrative reports of patient comfort levels are documented. Although cooling dialysate temperature was reported in one study, causing approximately 20% of patients to complain of shivering (van der Sande et al., 2009), other studies report only minimal patient complaints (Azar, 2009; Pizzarelli, 2007; Ramos et al., 2007). Complaints of vomiting, cramping, lightheadedness, and fatigue have been documented both in cooling HD (Azar, 2009; van der Sande et al., 2009) and during standard HD (Azar, 2009).

The purpose of this study was to examine thermal control of dialysate and patient comfort in an acute care dialysis unit. The objectives of this project led to three major research questions:

* To what extent does isothermal HD affect IDH in patients receiving HD at a community, acute care hospital?

* What is the association between isothermal HD and patient comfort?

* Do patients receiving isothermal HD report an increased level of specific discomfort symptoms as described in previous studies?

Literature Review

The most frequent interventions used to prevent IDH in outpatient studies include ongoing vigilant weight monitoring, patient adherence to dietary restrictions, avoiding feeding patients during treatment, thermal control of dialysate, holding antihypertensive medications, implementing sodium modeling, and using the ultra filtration profile (Jepson, 2009). However, in acutely hospitalized patients, weight, diet, and medications are often difficult to control due to the frequently changing patient condition.

Human body temperature is regulated by neural feedback mechanisms, and the temperature varies slightly due to environmental and metabolic factors. During standard hemodialysis, body temperature increases due to an inflammatory response, which causes vasodilatation resulting in hypotension (Cadena et al., 2008; Jepson, 2009).

For the past two decades, many studies have indicated that using thermal control of dialysate during HD reduces episodes of IDH (Azar, 2009; Pizzarelli, 2007; Ramos et al., 2007). Three methods of dialysate thermal control include isothermal, cooling, and thermoneutral HD, all of which reduce the body temperature increase caused by standard hemodialysis, and subsequently, reduce IDH. During standard HD, dialysate temperature is set at a recommended 37 to 37.5 degrees Celsius (Pizzarelli, 2007). Isothermal HD attempts to maintain the dialysate at the same temperature as the patient's body temperature, and therefore, body thermoregulation is minimally impacted by dialysis. Isothermal HD is done by setting the dialysate temperature equal to the patient's baseline temperature. Depending on temperature-monitoring capacity, the dialysate temperature may be adjusted periodically over the course of the HD treatment. Ideally, body temperature is constantly monitored, and any body temperature change results in dialysate temperature throughout the dialysis procedure. Cooling HD is done by cooling the dialysate temperature to 35.0 to 35.5 degrees Celsius (Pizzarelli, 2007), without regard to the patient's baseline body temperature. Cooling HD effectively prevents the increase in body temperature and resultant hypotension commonly found with standard HD; however, it may lower body temperature to symptomatic and uncomfortable levels. In thermoneutral HD, the dialysate temperature is adjusted to prevent heat exchange between the arteriovenous extracorporeal circuit so no energy is added to or removed from the patient. All three thermal control methods adjust dialysate temperature lower than standard HD.

According to van der Sande et al. (2009), central blood volume tends to be higher using cooling HD compared with isothermic and thermoneutral methods, but frequently contributes to patient discomfort, such as shivering and cramping. Isothermal HD has not only been reported to control hypotension, but also to minimize the side effects experienced during cooling HD (Azar, 2009; Pizzarelli, 2007; van der Sande et al., 2009). Azar (2009) examined preference among 50 patients who received both standard HD and cooling HD, and discovered 76% of patients preferred cooling HD, 14% of patients preferred continuing standard HD, and 10% of patients had no preference.

Theoretical Framework

Although there is mention of discomfort associated with thermal control HD, no consistent or recommended measurement of patient comfort was found in the nephrology literature. Kolcaba's Comfort Theory proposes an important relationship between patient comfort, patient behaviors that move the patient toward a state of well-being, and outcomes (Kolcaba & Wilson, 2002; Wagner, Byrne, & Kolcaba, 2006). Patient satisfaction, an important institutional outcome, may be related to patient comfort level during hospitalization or treatment. Kolcaba's Comfort Theory has been applied to perioperative, orthopedic, pediatric, psychiatric, and palliative care populations. For example, in the outpatient surgical setting, temperature is important in the patient's perception of comfort (Fossum, Hays, & Henson, 2001; Wagner et al., 2006). The Kolcaba General Comfort Scale has been adapted for use in multiple settings and has been translated into multiple languages (Kolcaba, 2010a)


Sample and Design

This study used a quasi-experimental design with two patient groups. The Standard HD Group (comparison group) was composed of participants who stated they did not have a history of IDH and received standard HD. The Isothermal HD Group (study group) received isothermal HD and included participants who stated they experienced IDH often in the past or whose pre-HD systolic blood pressure (SBP) was equal to or less than 110 mmHg during this study period. The SBP limit was based on the standard of care in the unit and consultation with a clinical nurse specialist, and was considered a conservative approach to minimize severe hypotensive episodes in these patients. Our goal with this pilot was to demonstrate the feasibility and safety of isothermal HD, which had not been used in our facility. The comparison group was designed to provide a standard of care comparison and to be able to accrue enough participants with history of hypotension into the study arm. Unfortunately, we did not have pre-study comfort data to provide historical comparisons.

This study was approved by the Nursing Research Committee, the medical director of nephrology, and the Institutional Review Board at the facility. The study included a convenience sample of adult participants who were admitted to an acute care hospital and received inpatient hemodialysis between March 7, 2011, and May 6, 2011. All adult patients admitted to the hospital hemodialysis unit were approached by a nurse experienced in hemodialysis who had received human subjects protection training and study-specific training to describe the study and seek consent to participate in the study. Exclusion criteria included patients who were medically unstable or unable to give consent. Inclusion criteria included patients 18 years of age or older. Inclusion criteria for the isothermal HD group included a history of hypotension during HD or a pre-HD SBP equal to or less than 110 mmHg.


Verbal Rating Comfort Scale. The Verbal Rating Comfort Scale is a variation for clinical documentation of Kolcaba's General Comfort Scale (Kolcaba, 2010b) and has shown correlation to the Healing Touch Comfort Questionnaire (Dowd, Kolcaba, & Steiner, 2006). This scale allows the participant to rate his or her total comfort using a Likert scale (0 = no comfort at all to 10 = highest comfort possible). Internal consistency of several versions of the Kolcaba's original scale ranged from 0.64 (End of Life Comfort Scale) to 0.82 (Urinary Incontinence and Frequency Comfort Questionnaire) (Dowd et al., 2006).

Patient flowsheet. Patient flowsheets utilized during routine HD visits were used to document age, gender, patient temperature, dialysate temperature, blood pressure, and dialysis-related interventions. Data were collected pre- and post-HD treatment.


Participants who consented and did not meet inclusion criteria for the isothermal HD group were placed in the comparison group and received standard HD, which was the standard of care currently used in the hemodialysis unit. For participants who consented and met the inclusion criteria for the isothermal HD group, the nephrologist of record was contacted to initiate an order for as-needed (pm) isothermal HD. The pm order would allow nurses to change the dialysate temperature back to standard HD if symptoms or participant preferences changed.

Each patient's blood pressure was measured pre- and post-HD, every 30 minutes, and as needed during HD. The patient's temperature was measured pre- and post-HD and as needed according to the standard practice procedures of the hemodialysis unit. The temperature was measured using a digital thermometer, and a dedicated thermometer was used for all patients in the study. These parameters, using the standard of care, were documented on the patient flowsheet.

The participant's comfort level was measured by the Verbal Rating Comfort Scale pre- and post-HD and recorded on the patient flowsheet. In addition, the flowsheet was used by RNs to record participant discomfort symptoms, such as shivering, vomiting, cramping, lightheadedness, and/ or fatigue. The nurse documented any complaints and subsequent nursing interventions (for example, provided blanket).


A total of 68 patients consented to participate in the study, with 59 completing the study. There were 28 participants in the isothermal HD group and 31 participants in the standard HD group. A total of 157 study cases (separate HD events) with complete data were analyzed using SPSS v. 18 (2009). Participant age range was 31 to 90 years. The mean age was 58 years. There were 38 (64%) male participants and 21 (36%) female participants. The standard HD group age ranged from 39 to 90 years (mean = 58.8 years), and the isothermal HD group age ranged from 31 to 83 years (mean = 57.2 years). Detailed demographics are shown in Table 1.

To answer the first research question concerning the relationship between isothermal HD and hypotension, t-tests were conducted. T-tests comparing pretreatment systolic blood pressure (SBP) between the two groups indicated significant differences. Participants in the isothermal HD group had significantly lower mean measures on their lowest treatment SBP (t = -4.54, p < 0.001) and lower mean pre-treatment SBP (t = -4.29, p < 0.001). However, the mean change from pre-SBP to either the lowest SBP or post-SBP was not significantly different between the two groups ip = 0.825 and p = 0.082, respectively). The use of isothermal HD did not modify the drop in SBP; these participants started with lower SBP, and the mean of their lowest SBP recorded during HD was also lower.

The change in blood pressure among the isothermal and standard HD groups is displayed in Figure 1. Comparing pre-HD SBP to the lowest SBP during HD or post-HD, 56% of participants in the isothermal HD group maintained their SBP within 15 mmHg compared to 54% in the standard HD group. Nineteen percent of participants in the isothermal HD group and 22% of participants in the standard HD group experienced a change in blood pressure between 16 to 30 mmHg, while 25% of participants in the isothermal HD group and 24% participants in the standard HD group experienced a change in blood pressure of more than 30 mmHg.

Findings related to the second research question, investigating the association between isothermal HD and patient comfort, were analyzed using t-tests. No significant differences in the change in comfort level between the two groups were found. The change in comfort level between the two groups is shown in Figure 2. The X axis represents ranges of change in the participant's comfort level, and the Y axis represents the percentage of participants in each group. For example, if a participant's pre-HD comfort level was 9 and the post-HD comfort level was 10, the participant's comfort level improved by 1 unit.

The third research question was related to the frequency of specific discomfort symptoms in the two groups. Comparing the comfort level change from pre-HD to post-HD, there was no significant difference between the two groups. Complaints of cold or shivering occurred in 33% of participants in the isothermal HD group compared to 15% of participants in the standard HD group (see Figure 3). Other complaints were rarely reported.


This study was an innovative attempt to demonstrate the usefulness of isothermal HD in the acute care setting. Generally, participants stated that their comfort level was not affected by using isothermal HD. Any discomforts experienced by participants were manageable with nursing interventions. This implies that implementing isothermal HD was not associated with change in the participant's comfort level because nursing care managed the problem quickly and effectively. Isothermal HD showed no statistically significant difference, compared to standard HD, in controlling hypotension in an acute care setting. Data indicated that the mean change from pre-HD SBP to either the lowest SBP during HD or postHD SBP was not significantly different between the two groups.


Some limitations to the study include routine temperature measurement and routine care related to hospital admission and HD. For example, a digital thermometer was used for routine axillary temperature measurement. The accuracy of the thermometer as reported by the manufacturer was +/-0.3 degree Celsius. Although core body temperature is the recommended procedure for isothermal dialysis, Pizzarelli (2007) supports the use of isothermal HD by monitoring peripheral body temperature if core body temperature measurement is unavailable. In this study, axillary body temperature was recorded, which may be less reliable and/or accurate than other measures of body temperature. Additionally, factors that could impact patient comfort relative to the hospital admission, such as environmental temperature, acute illness, and inpatient care, were not controlled. Finally, the reliability of the comfort tool was not assessed for this study.

The number of uncontrolled, intervening variables may have limited findings of statistical significance. Further research is recommended to determine the impact of uncontrolled intervening variable (such as length of HD treatment) and if isothermal HD may be an appropriate HD option for controlling intradialytic hypotension in the acute care setting. An alternate design should consider use of the patient as his or her own control in response to both isothermal HD and standard HD.

Conclusions and Implications For Nursing Practice

This pilot study explored and described the use of isothermal HD in an acute care setting and patient comfort issues associated with thermal control. The study is the first step in developing the evidence to support the use of isothermal dialysis in an acute care HD population. Quality nursing care, which improves hypotension tolerance, improves comfort level, prevents delay in treatment, increases successful completion of HD, and proves to be cost effective for patients on hemodialysis in an acute care setting, will result in improved outcomes for patients as well as the hospital.


To provide an overview of isothermal dialysis as a method of improving intradialytic tolerance in hypotension-prone patients in an acute care setting.


1. Review the background of isothermic regulation of hypotension in the outpatient dialysis setting.

2. Discuss the theoretical framework of Kolcaba's Comfort Theory.

3. Determine the implications of this study for nephrology nurses working in acute care settings.

Acknowledgement: We wish to acknowledge the invaluable assistance from the clinical registered nurses in the Dialysis Unit at SJHA for collecting the data for this study: Rachel Varghese, Jaitha Kalladanthyil, LisaWaugh, Kalpna Duvvuri, ElizpbethWallace, Dorothy Lucas, Frances Luecke, and Debby Goodwin. Additional appreciation is extended to the medical nephrologists whose patients participated in the study with special thanks to Dr. Gregory Knowlton, Dr. Anupama Gowda, Kevin Viel, PhD, and Beverly Smith, Manager of the Dialysis Unit, for supporting the study.


Azar, A.T. (2009). Effect of dialysate temperature on hemodialysis stability among hemodialysis patients. Saudi Journal of Kidney Diseases and Transplantation, 20(4), 596-603. Retrieved from asp?issn=1319-2442;year=2009; volume=20;issue=4;spage=596;epage =603;aulast=Azar

Cadena, M., Medel, H., Rodrguez, E, Flores, R, Mariscal, A., Franco, M. . . Escalante, B. (2008). Isothermic vs thermoneutral hemodiafiltration evaluation by indirect calorimetry. Retrieved from articulos/2008/EMBS_2008.pdf

Dowd, T., Kolcaba, K., & Steiner, R. (2006). Development of the Healing Touch Comfort Questionnaire. Holistic Nursing Practice, 20, 122-129.

Fossum, S., Hays J., & Henson M.M. (2001). A comparison study on the effects of prewarming patients in the outpatient surgery setting. Journal of Perianesthesia Nursing, 16, 187-194. doi: 10.1053/jpan.2001.24039

Ghasemi, A., Shaflee, M., & Rowghani K. (2008). Stabilizing effects of cool dialysate temperature on hemodynamic parameters in diabetes. Saudi Journal of Kidney Diseases and Transplantation, 19, 378-383.

Jepson, R. (2009). Protect your patient from dialysis hypotension. Nursing, 39, 55-56.

Kolcaba, K. (2010a). Comfort theory. Retrieved from

Kolcaba, K. (2010b). Comfort questionnaires. Retrieved from caba

Kolcaba, K., & Wilson, L. (2002). Comfort care: A framework for perianesthesia nursing. Journal of Perianesthesia Nursing, 17, 102-111. doi:10.1053/ jpan.2002.31657

Pizzarelli, F. (2007). From cold dialysis to isothermal dialysis: A 25-year voyage. Nephrology Dialysis Transplantation, 22, 1007-1012. doi:10.1093/ndt/ gfl822

Ramos, R., Soto, C., Mestres, R., Jara,J., Zequera, H., Merello, J.I., & Moreso, F. (2007). How can symptomatic hypotension be improved in hemodialysis patients: Cold dialysis vs. isothermal dialysis. Nefrologia, 27, 737741.

Selby, N.M., & McIntyre, C.W. (2006). A systematic review of the clinical effects of reducing dialysis fluid temperature. Nephrology Dialysis Transplantation, 21, 1883-1898. doi: 10. 1093/ndt/gfll26

van der Sande, F.M., Wystrychowski, G., Kooman, J.P., Rosales, L., Raimann, J" Kotanko, P, ... Levin, N.W. (2009). Control of core temperature and blood pressure stability during hemodialysis. Clinical Journal of the American Society of Nephrologists, 4, 9398. doi:10.2215/CJN,01800408

Wagner, D., Byrne, M., & Kolcaba, K. (2006). Effects of comfort warming on preoperative patients. Association of Perioperative Registered Nurses Journal, 84, 427-448. doi: 10.1016/ S0001-2092(06)63920-3

Jianjun "Jan" Li, BSN, RN, CNN, was a Staff Nurse, the Dialysis Unit, SaintJoseph's Hospital, Atlanta, GA., and is currently a student in the MBA/MHA program at University of Georgia. She is a member of ANNA's Dogwood Chapter and may be contacted directly via email at

Lanell Bellury, PhD, RN, AOCNS, is an Associate Professor, Mercer University, Georgia Baptist College of Nursing, Atlanta, GA.

Marianne Baird, MN, RN, ACNS-BC, PCCN, is a Clinical Nurse Specialist and Magnet*' Program Director, Emory Healthcare System, Atlanta, GA.

Lewis N. Van Brackle, PhD, is a Professor of Statistics, Kennesaw State University, Kennesaw, GA.

Kathie Aduddell, EdD, MSN, RN, is Director and a Professor of Nursing, Texas Lutheran University, Seguin, TX.

Note: Authors' biographical statements and acknowledgments can be found on the following Page Statement of Disclosure: The authors reported no actual or potential conflict of interest in relation to this continuing nursing education activity.

Note: Additional statements of disclosure and instructions for CNE evaluation can be found on page 281

Table 1
Demographic Data

                                Standard HD      Isothermal HD
                   Sample          Group             Group
                  (N = 59)       (N = 28)          (N = 31)
Age in Years
Mean (Range)     58 (31-90)   58.8 (39 to 90)   57.2 (31 to 83)

  Male N (%)      38 (64%)
  Female N (%)    21 (36%)

Table 2
Comparison of Groups

                          Standard HD Group (N = 88)

                             Group            n (%)

Change in systolic         5 or less         25 (28)
blood pressure              6 to 15          23 (26)
                            16 to 30         19 (22)
                            31 to 45         15 (17)
                           46 or more         6 (7)

Change in comfort          Up 4 to 5          4 (5)
level                      Up 2 to 3         15 (17)
                      Up 1 to 0 to down 1    60 (68)
                          Down 2 to 3         6 (7)
                          Down 4 to 5         3 (3)

Complaints               Cold/shivering      13 (15)
                            Fatigue            1 0)
                        Nausea/vomiting       3 (3)
                            Cramping          3 (3)
                        Lightheadedness       0 (0)

                        Isothermal HD Group (N = 69)

                             Group            n (%)

Change in systolic         5 or less         21 (30)
blood pressure              6 to 15          18 (26)
                            16 to 30         13 (13)
                            31 to 45         13 (19)
                           46 or more         4 (6)

Change in comfort          Up 4 to 5          2 (3)
level                      Up 2 to 3          8 (12)
                      Up 1 to 0 to down 1    55 (80)
                          Down 2 to 3         3 (4)
                          Down 4 to 5          1 (D

Complaints               Cold/shivering      33 (23)
                            Fatigue           2 (3)
                        Nausea/vomiting       0 (0)
                             Cramp             1 0)
                        Lightheadedness       0 (0)
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Article Details
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Title Annotation:Continuing Nursing Education
Author:Li, Jianjun "Jan"; Bellury, Lanell; Baird, Marianne; Van Brackle, Lewis N.; Aduddell, Kathie
Publication:Nephrology Nursing Journal
Article Type:Report
Geographic Code:1USA
Date:May 1, 2014
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