What are the Consequences of Volume Expansion in Chronic Dialysis Patients?

Variable-Volume Kinetic Model to Estimate Absolute Blood Volume in Patients on Dialysis Using Dialysate Dilution

Long- and short-term adverse outcomes in hemodialysis (HD) have been associated with intradialytic hypotension, a common HD complication and significant cause of morbidity. It has been suggested that knowledge of absolute blood volume (ABV) could be used to significantly improve treatment outcomes. Different dilution-based protocols have been proposed for estimating ABV, all relying on the classic mono-exponential back-extrapolation algorithm (BEXP). In this paper, we introduce a dialysate dilution protocol and an estimation algorithm based on a variable-volume, two-compartment, intravascular blood water content kinetic model (VVKM). We compare ABV estimates derived using the two algorithms in a dialysate dilution study including three arterio-venous (AV) and three central-venous (CV) access patients, and multiple bolus injection tests (3-5) within each of several (2-6) HD treatments. The distribution of differences between ABV estimated from the two methods showed negligible systematic difference between the mean values of ABVs estimated from the BEXP and VVKM algorithms, however, the VVKM estimates were 53% and 42% more precise for the CV and AV patients, respectively. Good agreement was observed between measured and VVKM-estimated blood water concentration with the root-mean-square error (RMSE) less than 0.02 kg/kg (2%) and 0.03 kg/kg (3%) for AV and CV patients, respectively. The dilution protocol and the new VVKM-based estimation algorithm offer a noninvasive, inexpensive, safe, and practical approach for ABV estimation in routine HD settings.

Measuring the prevalence of intradialytic hypotension in a satellite dialysis clinic: Are we too complacent?

AIMS AND OBJECTIVES

To measure the prevalence of symptomatic (S-IDH) and asymptomatic intradialytic hypotension (A-IDH) or postdialysis overhydration in a satellite haemodialysis clinic in Western Australia.

BACKGROUND

Intradialytic hypotension is one of the most common side effects of haemodialysis caused by ultrafiltration provoking a temporary volume depletion. The prevalence of asymptomatic hypotension during dialysis has been rarely reported, but is considered to have the same negative consequences as symptomatic hypotension on various end organs like the brain and the gastrointestinal tract.

DESIGN

Observational study on a retrospective 3-month period of nursing recorded fluid-related adverse events.

METHODS

Data collection on the occurrence of S-IDH and A-IDH during a total of 2,357 haemodialysis treatments in 64 patients. Body weight of patients at the time of cessation of treatment was recorded, and patients, whose weight exceeded their ideal body weight by at least 0.5 kg, were classified as overhydrated. Data analysis was performed using spss version 24 software.

RESULTS

Symptomatic intradialytic hypotension was the most common adverse event measured in this cohort, and occurred during 221 (9.4%) of all treatments, whereas asymptomatic intradialytic hypotension occurred in 88 (3.7%) of all treatments. The total occurrence of intradialytic hypotension was 13.1%, and symptomatic was observed in 30 patients, implying that nearly every second patient had at least one symptomatic episode within 3 months. Overhydration occurred in a total of 103 (4.4%) of all treatments, and involved 17 patients.

CONCLUSIONS

Symptomatic and asymptomatic intradialytic hypotension were the most commonly observed adverse events in this cohort; overhydration occurrence was considerably less common.

RELEVANCE TO CLINICAL PRACTICE

The high occurrence of hypotension-related events demonstrates that ultrafiltration treatment goals in satellite dialysis clinics are sometimes overestimated, resulting in regular significant symptomatic episodes for the patient. Raising the awareness of the prevalence of IDH amongst renal nurses could be an essential initial step before collectively preventative strategies in haemodialysis satellite units are implemented.

Higher Ultrafiltration Rate Is Associated with Longer Dialysis Recovery Time in Patients Undergoing Conventional Hemodialysis

BACKGROUND

Increased mortality and morbidity are reported in association with high ultrafiltration rate (UFR) and with long dialysis recovery time (DRT). We studied the association between UFR and DRT.

METHODS

This is a cross-sectional, observational study was conducted. Patients on thrice-weekly hemodialysis (HD) with self-reported DRT between August and December 2014 were included. We examined the association of 30-day average UFR with recovery time.

RESULTS

The total number of patients included in this study was 2,689. DRT in categories of immediate recovery, >0-≤2, >2-≤6, >6-≤12, and >12 h, were reported in 27, 28, 17, 9, and 20% of the patients respectively. In multivariable analysis, longer DRT was associated with female gender, non-black race, higher body weight, lower serum albumin, chronic heart failure, cerebrovascular disease, missed dialysis sessions, higher pre-dialysis systolic blood pressure, and larger UF volume. Compared to UFR of <10, UFR ≥13 mL/kg/h was associated with longer DRT, OR of 1.16 (95% CI 0.99-1.36), and 1.28 (95% CI 1.06-1.54) in the unadjusted and the adjusted analyses respectively. Intradialytic hypotension was also associated with longer DRT in the unadjusted (per 10% higher frequency, OR 1.04 [95% CI 1.01-1.07]) and adjusted analyses (OR 1.03 [95% CI 1.00-1.07]).

CONCLUSION

Long recovery time is common after HD. Rapid fluid removal is associated with longer DRT.

Use of ultrasound by registered nurses-a systematic literature review

BACKGROUND

In Western Australia (WA), most stable patients undergoing haemodialysis receive treatment in a satellite setting where no doctors are on-site during treatment hours, so nurses must make critical decisions about fluid removal. Some patients regularly experience adverse events during dialysis (intradialytic), often due to excessive ultrafiltration goals, with intradialytic hypotension being particularly challenging. Ultrasound of the inferior vena cava has been previously demonstrated being a rapid and non-invasive method for volume assessment on haemodialysis patients, thus could hold valuable information for the treating nurse.

AIM

This paper examines the existing literature in regards to the use of ultrasound measurements of the inferior vena cava in patients on haemodialysis for objective assessment of their intravascular volume status by renal nurses.

METHOD

A systematic literature review was performed within medical and nursing databases including CINAHL Plus with Full Text, SCOPUS, Web of Science and MEDLINE.

RESULTS

Renal nurses are conscious of the significance of intradialytic hypotension and have only limited options for its prevention. Ultrasound of the inferior vena cava could add another objective dimension for intravascular volume assessment and prevention of intradialytic hypotension, but to date renal nurses have not been using this technique.

CONCLUSIONS

Ultrasound of the inferior vena cava has the potential to assist in defining the ultrafiltration goal for that particular dialysis session, thus reducing the risk of intradialytic hypotension. Additionally, it has potential to change current renal nursing practice when added to clinical nursing assessment methods. Further studies are required to validate this assessment tool carried out by a renal nurse compared with a skilled ultrasonographer.