Abstract

Intradialytic hypotension is defined as a decrease in systolic blood pressure by ≥ 20 mm Hg or a decrease in mean arterial pressure by 10 mm Hg, and is associated with symptoms that include abdominal discomfort, yawning, sighing, nausea, vomiting, muscle cramps, restlessness, dizziness or fainting, and anxiety. The incidence of a symptomatic reduction in blood pressure during (or immediately following) dialysis ranges from 15-50% of dialysis sessions. It is a major cause for morbidity in elderly hemodialysis patients and those with cardiovascular compromise. It impairs patient well-being, limits ultrafiltration, and increases the risk for coronary and cerebral ischemic events as well as vascular access thrombosis. Several studies have shown a poorer survival in dialysis patients who experience frequent hypotensive episodes on dialysis as opposed to those who do not. In our outpatient dialysis unit, we identified that 9% of our dialysis patients experienced a decrease in their systolic blood pressure to below 80 during dialysis. The purpose of this quality improvement project was to study the factors associated with intradialytic hypotension in these patients and institute appropriate measures to mitigate this issue. Another aim was to educate the dialysis staff on how to manage these patients. Patients were selected using data from weekly rounding reports and orders were written for interventions including ultrafiltration profiling, cool (36 °C) dialysate, weight-based ultrafiltration, etc. Outcomes were studied over a period of 3 months. We found that up to 40% of patients experienced an improvement in their blood pressure profile over the period of the study, suggesting that simple changes to dialysis prescription can result in a significant reduction in the incidence of intradialytic hypotension.

 

Introduction

Intradialytic hypotension (IDH) is a serious cause for morbidity and mortality in hemodialysis patients. The incidence of a symptomatic reduction in blood pressure (BP) during or immediately following dialysis ranges from 15-50% of dialysis sessions.1Despite this significant impact, IDH is not routinely reported or aggregated in U.S. dialysis facilities. This lack of categorized reporting makes it difficult to assess the overall frequency and impact of IH and may hinder routine medical management.2

IDH can lead to increased incidence of ischemic events, both cardiovascular and cerebral, vascular access thrombosis, arrhythmias, fluid overload, and interdialytic hypertension due to limited ultrafiltration (UF).3-7 Most of all, it impairs the well-being of these patients and negatively affects their quality of life. In some patients, the development of orthostatic hypotension necessitates intravenous fluid replacement before they are able to leave the dialysis unit. Intradialytic hypotension can result from various causes, including rapid fluid removal in an attempt to attain “dry weight,” particularly among those with large interdialytic weight gains; diminished cardiac reserve and intake of medications that alter cardiovascular stability, and use of low-sodium dialysate or ingestion of a meal immediately before or during dialysis. The relative magnitude of the contribution of each of these factors is not known. This problem contributes to the excessive morbidity that is associated with the dialysis procedure, including at our own clinic.

 

Purpose

We describe a quality improvement project that was designed to identify and address various risk factors leading to intradialytic hypotension in maintenance hemodialysis patients. These included both patient-related and dialysis-related risk factors. This study was carried out at our outpatient dialysis center.

 

Participants

In developing unit-specific goals, protocols, and monitoring for fluid and BP control as mandated by the ESRD Networks, we found that about 9% of our hemodialysis patients frequently dropped their systolic pressure below 80 during dialysis. Data for all patients who had been on dialysis for at least three months or more were reviewed for inclusion in this study.

 

Material and methods

This study was performed in two phases. During phase 1, data regarding BP variations for these patients was followed consistently for three months. A literature review was conducted to identify strategies recommended for IDH. Nine patients who were demonstrating IDH in > 50% of their dialysis sessions were identified. Seven patients were enrolled in this phase of the study. Two patients were not included due to unavailability of consistent data regarding their dialysis treatments. KDIGO (Kidney Disease: Improving Global Outcomes) guidelines regarding strategies to overcome IDH were reviewed. Orders were written for cool dialysate (36 °C), weight-based (less than or equal to 4% of total body weight) ultrafiltration, and UF profiling (linear vs. stepwise, based on underlying cardiac status and tolerability to UF). Sodium profiling was not used, as data regarding its benefit in reducing IDH is controversial and significant individual and interdialysis variations in sodium levels exist. Also it is sometimes associated with thirst and weight gain associated with post-dialysis hypertension.

Other variables that could possibly affect BP including hemoglobin, albumin, BP medications, average interdialytic weight gain, and cardiac status (ejection fraction [EF] on last Echo performed) were also studied. Dialysis staff was educated about the project and expected outcomes in home-room meetings. Compliance with orders was monitored intermittently and outcomes were evaluated at six weeks.

The following interventions were performed:

1.              Limit UF to <4% of body weight during each dialysis session.

2.              Lower dialysate temperature to 36 °C.

3.              Minimize use of BP-lowering medications prior to dialysis session.

4.              Conduct dietary education on limitation of fluid and salt intake by the renal dietitian.

5.              Discourage eating immediately before or during dialysis.

6.              Educate staff about the changes to dialysis prescription and rationales.

7.              Monitor that patients who were already taking midodrine to support their BP remain on this medication for the duration of the study.

8.              Evaluate in detail antihypertensive regimens for each individual patient.

9.              Ask patients to take their single-dose medications preferably at night and ask those who were on multiple antihypertensive medications to hold some of them prior to dialysis.

10.           Dialyze all patients using a fixed sodium bath of 137. Sodium profiling was not performed.

11.           Analyze patients’ dry weights at regular intervals and make changes as deemed appropriate by the physician.

12.           Maximize diuretic use for patients who had residual renal function.

 

Results

Table 1 describes the total number of treatments that each patient underwent and lowest BP during treatments. The mean number of treatments per patient was 39.7 and mean number of treatments per patient where SBP remained > 80 was 31.8. This was improved from their previous records. However, as indicated in Table 1, orders for cool dialysate and weight-based profiling were not applied in all dialysis treatments. Orders for cool dialysate were followed in an average of 50-75% of the treatments among the 7 patients studied. Orders for weight-based profiling were followed in about 85-100% of the treatments. For some of the patients (especially #1, #2, and #5 in Table 1), the lowest BP measurements during treatment still remained low but the number of treatments where SBP remained > 80 was increased with these interventions.

Staff compliance with orders and patient tolerance were major challenges to following these measures. At the end of phase 1, we found that intradialytic BP improved in 40% of the patients studied, irrespective of their underlying cardiac status. Hemoglobin values and albumin were found to have no significant association with intradialytic hypotension. However, a statistical analysis was not performed.

Based on results of phase 1 of the study, we extended our project to include patients whose systolic blood pressure decreased to <100 during dialysis. During phase 2, additional interventions performed included:

1.                        Increase dialysate calcium to 2.5 meq/L (unless contraindicated due to hypercalcemia)

2.                        Limit interdialytic weight gain to the recommended range (2-3 kg on average)

3.                        Intensify staff education and monitoring to ensure compliance with orders.

Phase 2 interventions were found to have less of an impact on improving BP profile during dialysis treatments. Many patients did not show any improvement because of non-compliance to dialysis treatments—either missing completely or cutting short their treatments. We also recognized that patient education regarding limiting interdialytic weight gain had to be reinforced frequently. In 30% of the patients during phase 2 of this study, IDH with SBP <100 occurred in < 30% of the treatments. In those where IDH incidence was much higher, either non-compliance with treatments, treatment orders or medication use was observed. Following of orders by the staff was also very inconsistent (see Table 2).

  • Patients whose BP profile did not improve despite these interventions were identified to have one of the following limiting factors:
  • Poor cardiac function—low EF on last documented Echo or h/o severe coronary artery disease and congestive heart failure
  • Labile BP requiring multiple BP meds
  • Other serious co-morbidities, such as late-stage diabetes, multiple myeloma, etc.
  • Non-compliance with treatments as mentioned above.
  • Severity of anemia and hypoalbuminemia, did not show any major correlation to the incidence of IDH in our HD population.

Applications in clinical practice

Prevention and treatment of IDH requires a multidisciplinary approach involving the physician, nurse practitioner, physician assistant, dialysis nurse, dialysis technician, dietitian, and social worker, as well as the patient. Ideally, after patients with frequent IDH have been identified, assessment and a new plan of care can be developed during routine care plan meetings in which all of the team can be present. After group discussion that includes the patient, the appropriate strategies can be selected and all parties can have an opportunity to ask questions. Since many of the strategies are very patient-dependent, discussion should include how each strategy selected can help decrease IDH to increase both patient and staff compliance. Limiting fluid and salt, taking the correct dose of medication at the right time of day, coming to dialysis treatments and staying the prescribed time can all play a role in decreasing IDH.

Empowering the patient to take control can improve their outcomes. Having them bring a small thermos of strong coffee to drink during the last hour of dialysis can help. Caffeine blocks adenosine, which can cause vasodilatation. Likewise, support and encouragement from all of the dialysis team should be evident at each session. During predialysis assessment, praise and /or concern can be made as the patient’s weight and blood pressure are taken. Probative questions can be asked to identify causes for variances in expected outcomes. UF profiling and dialysate temperature, if ordered, should be mentioned as they are programmed into the dialysis machine so that the patient is aware they are getting the individualized care that was discussed and ordered. The dialysis staff should have training on assessment and evaluation of hypotension and options that they can use to decrease the risks of IDH.

Automatically stopping UF or administering intravenous fluids can be counter-productive and should be avoided unless absolutely necessary. If large weight gains continue to be an issue, encouraging a weekly food diary can be helpful so the dietitian can identify high-sodium foods the patient is eating that could be either decreased or eliminated from their diet. Lower sodium alternatives can then be suggested. If transportation, inability to get prescriptions filled, changes in social support, openness for counseling or drug rehabilitation or other psychosocial problems are identified, the social worker can explore options with the patient and involve the medical team when necessary. When the medical team rounds, the same degree of concern about interdialytic weight gains, blood pressure, and other outcomes should be evident. Interventions that are either working well or need modification can be addressed chair-side with input from all parties. The patient’s dialysis prescription and/or medications can then be adjusted according to their response to therapy, and barriers to success can be identified and referred to the appropriate team member for further follow-up or intervention. Working together in a consistent, positive, focused manner promotes the caring environment needed to support change in these complex patients. The improved communication and education obtained through these interactions can also improve both patient and staff satisfaction.

Patients who continue to have frequent hypotensive episodes on dialysis despite maximal intervention may need longer treatment times to either decrease the ultrafiltration rate or allow time for isolated ultrafiltration at the beginning of dialysis. Also, extra dialysis sessions, usually up to two per month, could be done for volume overload. For patients with heart failure or who are unable or unwilling to limit their fluid and salt intake, switching to a home dialysis modality where daily or almost daily treatments are done may be helpful. These strategies could be discussed in the initial care plan meeting so that the patient knows what options may be available if they continue to have either blood pressure and/or volume problems. Patients identified as having resistant IDH should be evaluated further for causation.

 

Conclusion

This project identified some simple measures that were found to be effective in improving fluid management in hemodialysis patients with frequent IDH. The measures outlined above, including UF profiling, limiting UF to <4% of body weight, lowering dialysate temperature, focusing patient education on salt and fluid limits and maximizing diuretic use, as tolerated, in patients with residual renal function, can be employed to reduce the incidence of intradialytic hypotension in many hemodialysis patients. Individualization of the hemodialysis prescription is needed but is often difficult for staff to consistently deliver. Staff compliance is a key factor, especially in changing dialysate temperature manually. Lowering the temperature on all patients, so individualization of dialysate temperature is not needed, may be a better approach.

The major hindrance seen with this intervention was patient intolerance to the cooler dialysate, with resulting chills. This could be a major problem in winter months. Medical devices that can monitor intradialytic blood volume so that ultrafiltration can be better managed could also be an effective strategy, but these are not available in our unit.

Even after employing these measures, there remained a small proportion of patients who showed no improvement in their BP profile during treatments. These patients most likely had what is labeled as resistant IDH.

Acknowledgements

The authors would like to thank Cindy Reid for editing assistance.

References

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