Effect of intravenous fluids on blood pressure course during hemodialysis in hypotensive-prone patients

Intravenous Albumin for Mitigating Hypotension and Augmenting Ultrafiltration during Kidney Replacement Therapy

Among its many functions, owing to its oversized effect on colloid oncotic pressure, intravascular albumin helps preserve the effective circulatory volume. Hypoalbuminemia is common in hospitalized patients and is found especially frequently in patients who require KRT either for AKI or as maintenance hemodialysis. In such patients, hypoalbuminemia is strongly associated with morbidity, intradialytic hypotension, and mortality. Intravenous albumin may be administered in an effort to prevent or treat hypotension or to augment fluid removal, but this practice is controversial. Theoretically, intravenous albumin administration might prevent or treat hypotension by promoting plasma refilling in response to ultrafiltration. However, clinical trials have demonstrated that albumin administration is not nearly as effective a volume expander as might be assumed according to its oncotic properties. Although intravenous albumin is generally considered to be safe, it is also very expensive. In addition, there are potential risks to using it to prevent or treat intradialytic hypotension. Some recent studies have suggested that hyperoncotic albumin solutions may precipitate or worsen AKI in patients with sepsis or shock; however, the overall evidence supporting this effect is weak. In this review, we explore the theoretical benefits and risks of using intravenous albumin to mitigate intradialytic hypotension and/or enhance ultrafiltration and summarize the current evidence relating to this practice. This includes studies relevant to its use in patients on maintenance hemodialysis and critically ill patients with AKI who require KRT in the intensive care unit. Despite evidence of its frequent use and high costs, at present, there are minimal data that support the routine use of intravenous albumin during KRT. As such, adequately powered trials to evaluate the efficacy of intravenous albumin in this setting are clearly needed.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Hyperoncotic Albumin Reduces Net Fluid Loss Associated With Hemodialysis

Purpose: The purpose of this study was to compare the volume of fluid removal associated with and without 25% albumin administration in conjunction with hemodialysis. Methods: This retrospective, cohort study was conducted at a large academic medical center over a 6-month period to compare the net fluid amount removed (mL) during hemodialysis between patients administered 25% albumin and those without albumin. Results: A total of 238 patients consisting of 973 unique hemodialysis sessions were evaluated. The mean overall net fluid removed by hemodialysis in the 25% albumin and no albumin groups were 1242 mL and 1899 mL, P < .001, respectively. No albumin group had significantly higher mean fluid losses compared with 25% albumin for a total dose of either 25 g (P = .001) or 50 g (P = .001). There were no significant differences in mean fluid loss between the no albumin group and patients receiving 75 g or 100 g of albumin. Post hoc analysis failed to demonstrate a dose-dependent response in those patients receiving 25% albumin and no albumin. Conclusion: Hyperoncotic albumin administered during hemodialysis sessions reduced net fluid loss associated with hemodialysis. The findings of this study do not support the routine use of 25% albumin to improve fluid removal during dialysis.

Application of Unit-Level Cost Transparency, Education, Enhanced Audit, and Feedback of Anonymized Peer Ranking to Promote Judicious Use of 25% Albumin in Critical Care Units

Objective: Hyperoncotic 25% albumin is widely used for fluid resuscitation in intensive care units. However, this practice remains controversial. By 2012 in our intensive care unit, annual 25% albumin expenditures had steadily increased to exceed $1 million. This prompted efforts to promote more judicious use. Design: Prospective time series cohort analysis using statistical process control charts. Setting: Seventy-six-bed quaternary level cardiovascular surgical intensive care unit (CVICU), organized into 6 adjacent units. Patients: Adult cardiac, thoracic, and vascular surgery patients admitted postoperatively to the CVICU during the study period. Interventions: Over 12 months starting March 2013, we sequentially implemented unit-level 25% albumin cost transparency, provider education, and individualized audit and feedback of anonymized peer ranking of albumin prescriptions. Measurements and Main Results: C control charts were used for analysis of monthly unit-level direct albumin costs for 20 months. Balance measures including red cell transfusions, number of diagnoses of pleural effusions, and length of stay were also tracked. Monthly average albumin expenditures had decreased 61% by December 2014, and there was no evidence of adverse changes in any of the balance measures. These reductions have been sustained. Conclusion: Sequential implementation of multimodal strategies can alter clinician practices to achieve substantial unit-level reduction in 25% albumin utilization without harm to patients.

Evaluation of Albumin 25% Use in Critically Ill Patients at a Tertiary Care Medical Center

Background: Albumin 25% has been studied and has demonstrated benefit in a limited number of patient populations. The use of albumin 25% is associated with higher costs compared with crystalloid therapy. The aim of this study was to describe the prescribing practices of albumin 25% at a tertiary-care medical center and identify opportunities for restriction criteria related to its use to help generate cost savings. Methods: This evaluation was a retrospective, noninterventional, descriptive study of albumin 25% use between June 2015 and February 2016. Inclusion criteria consisted of patients ≥18 years old and who received at least one dose of albumin 25% while admitted to a Cleveland Clinic main campus intensive care unit (ICU). Inclusion was restricted to 150 randomly selected patients. Results: A total of 539 albumin 25% orders were placed for the 150 included patients. The cardiovascular ICU more frequently prescribed albumin 25% compared with the medical, surgical, neurosciences, and coronary ICUs (51% vs 23% vs 11% vs 9% vs 6%, respectively). Although the cardiovascular surgery ICU most frequently prescribed albumin 25% compared with other ICUs, the medical ICU prescribed a larger total quantity of albumin 25% compared with the cardiovascular, surgical, neurosciences, and coronary ICUs (8705 g vs 7275 g vs 3205 g vs 2162 g vs 625 g, respectively). The majority of patients (61%) did not have an indication listed for albumin 25% use and only 9% of patients were prescribed for indications supported by primary literature. Of the patients prescribed albumin for other indications not supported by primary literature (30%), the most common reasons for albumin 25% were hypotension, acute kidney injury, and volume resuscitation. The median cost per patient of albumin 25% was $417 with a total cost of $122 164 for the cohort. Only 19% of the total cost aligned with dosing regimens evaluated in primary literature. Conclusion: Prescribing patterns of albumin 25% at a tertiary academic medical center do not align with indications supported by primary literature. These findings identified a major opportunity for prescriber education and implementation of restriction criteria to target cost savings.

Implementation of an Algorithm Utilizing Saline Versus Albumin for the Treatment of Intradialytic Hypotension

Background: Intradialytic hypotension (IDH) is the most commonly reported complication of hemodialysis (HD) treatment. At our institution, dialysis patients often have both 25% albumin and normal saline ordered as rescue options for management of IDH, without specification of which agent to use first. Objective: The purpose of this study was to determine the effect of an algorithm for IDH management. Methods: A retrospective study was conducted in HD patients who experienced IDH. The primary end point was to evaluate albumin use. Secondary end points included albumin costs, study fluid use per dialysis session, compliance with algorithm, efficacy of hypotension reversal to mean arterial pressure (MAP) ⩾60 mm Hg, percentage of target ultrafiltration achieved, time required to restore systolic blood pressure ⩾90 mm Hg, blood pressure post–study fluids, IDH treatment failure rate, and early termination of dialysis as a result of persistent IDH. Results: Implementation of the algorithm was observed in 94% of patients (n = 90). Total albumin use was significantly reduced from 11 400 to 4700 mL in the pre– (n = 90) and post–algorithm implementation group (n = 90; P < 0.001). The associated total cost of albumin was reduced by 59% ($10 534 vs $4343; P < 0.001). No statistical differences were observed between the 2 groups regarding efficacy of hypotension reversal to MAP ⩾60 mm Hg, early HD termination, or treatment failure rates (all P = 0.99). Conclusion and Relevance: Implementation of an evidence-based, standardized algorithm and pharmacy education to nursing staff can result in a reduction in albumin use and its associated drug costs for IDH management without compromising efficacy of IDH reversal.

Bioimpedance monitoring of cellular hydration during hemodialysis therapy

Introduction The aim of this paper is to describe and demonstrate how a new bioimpedance analytical procedure can be used to monitor cellular hydration of End Stage Renal Disease (ESRD) patients during hemodialysis (HD). Methods A tetra-polar bioimpedance spectroscope (BIS), (UFI Inc., Morro Bay, CA), was used to measure the tissue resistance and reactance of the calf of 17 ESRD patients at 40 discrete frequencies once a minute during dialysis treatment. These measurements were then used to derive intracellular, interstitial, and intravascular compartment volume changes during dialysis. Findings The mean (± SD) extracellular resistance increased during dialysis from 92.4 ± 3.5 to 117.7 ± 5.8 Ohms. While the mean intracellular resistance decreased from 413.5 ± 11.7 to 348.5 ± 8.2 Ohms. It was calculated from these data that the mean intravascular volume fell 9.5%; interstitial volume fell 33.4%; and intracellular volume gained 20.3%. Discussion These results suggest that an extensive fluid shift into the cells may take place during HD. The present research may contribute to a better understanding of how factors that influence fluid redistribution may affect an ESRD patient during dialysis. In light of this finding, it is concluded that the rate of vascular refill is jointly determined with the rate of "cellular refill" and the transfer of fluid from the intertitial compartment into the intravascular space.

Detection of microcirculatory impairment by transcutaneous oxymetry monitoring during hemodialysis: an observational study

Background

Little is known about the effects of intermittent hemodialysis on microcirculatory perfusion. The aim of this study is to assess the effects of hemodialysis on microvascular perfusion using transcutaneous oxymetry (TCPO2).

Methods

In this observational study, hourly TCPO2 measurements were performed during hemodialysis sessions. Ankle brachial index (ABI) was carried out to classify patients according their vascular condition.

Results

50 patients (mean age 70 ± 8 years old) were enrolled. Mean TCPO2 decreased significantly on average 23.9% between start and finish of hemodialysis. Severe ischemia (TCPO2 < 30 mmHg) and critical ischemia (TCPO2 < 10 mmHg) occurred during dialysis in 47.1% and 15.5% respectively. Critical ischemia occurred only in limbs with ABI < 0.9 (8.3%) or > 1.3 (28%). Patients with critical ischemia experienced a significantly larger decline in mean blood pressure (32.4 ± 26.1 mmHg vs 12.7 ± 10.7 mmHg; P = 0.007) and a more pronounced ultrafiltration (45.55 ± 16.9 ml/kg vs 35.17 ± 18.2 ml/kg; P = 0.04) compared to patients without ischemia. Clinical outcomes (death or vascular procedures) were five times more frequent in patients who had developed critical ischemia (55.7% vs 10.1% P = 0.01). The elevated age of patients, the low basal value of TCPO2, and the occurrence of critical ischemia were more frequently associated with clinical outcome (P = 0.03, P = 0.048, P = 0.01 respectively).

Conclusions

This study demonstrates that hemodialysis induces microcirculatory injury, dependent on blood pressure reduction, peripheral vascular state and ultrafiltration. The occurrence of critical ischemia is associated to pejorative patient outcome and therefore, TCPO2 seems to be useful to avoid potential distal tissue damage during hemodialysis.

Monitoring intracellular, interstitial, and intravascular volume changes during fluid management procedures

The bioimpedance spectroscopic (BIS) analytical algorithm described in this report allows for the non-invasive measurement of intravascular, interstitial, and intracellular volume changes during various fluid management procedures. The purpose of this study was to test clinical use feasibility and to demonstrate the validity of the BIS algorithm in computing compartmental volume shifts in human subjects undergoing fluid management treatment. Validation was performed using volume changes recorded from 20 end stage renal disease patients. The validation procedure involved mathematically deriving post hoc hematocrit profiles from the BIS data-generated fluid redistribution time profiles. These derived hematocrit profiles were then compared to serial hematocrit values measured simultaneously by a CritLine(®) monitor during 60 routine hemodialysis sessions. Regression and Bland-Altman analyses confirm that the BIS algorithm can be used to reliably derive the continuous and real-time rates of change of the compartmental fluid volumes. Regression results yielded a R (2) > 0.99 between the two measures of hematocrit at different times during dialysis. The slopes of the regression equations at the different times were nearly identical, demonstrating an almost one-to-one correspondence between the BIS and CritLine(®) hematocrits. Bland-Altman analysis show that the BIS algorithm can be used interchangeably with the CritLine(®) monitor for the measurement of hematocrit. The present study demonstrates for the first time that BIS can provide real-time continuous measurements of compartmental intravascular, interstitial and intracellular fluid volume changes during fluid management procedures when used in conjunction with this new algorithm.

[Fluid overload and arterial hypertension in hemodialysis patients]

The water sodium overload is a factor of morbi-mortality and its treatment is one of the markers of adequacy of the hemodialysis treatment. Its first clinical assessment was improved by tools such as echocardiography and ultrasonography of the inferior vena cava, the per-dialytic curve of plasma volume, measuring BNP or proBNP and by impedancemetry. The combination of the evaluation of these parameters and of the clinical situation allows one to assess the extracellular overload, the state of the blood volume and the potential of plasma refilling. The latter is a key factor of the per-dialytic hemodynamic tolerance. It is itself a determining factor in weight can be achieved at the end of the session. Getting the "dry" weight can require modifications of the prescriptions of the hemodialysis sessions, a filling by albumin even a drugs support. Finally, the overload treatment is the central part of the treatment of arterial hypertension, which has to benefit however often from antihypertensive treatment the profit of which is demonstrated.

Modulation of oxidative stress and microinflammatory status by colloids in refractory dialytic hypotension

Background

Intradialytic hypotension may adversely affect the outcome of chronic hemodialysis. Therapeutic albumin has powerful anti-oxidant and anti-inflammatory properties. We have recently shown that systematic colloid infusion during hemodialysis sessions improves hemodynamic parameters in most dialysis hypotension-prone patients unresponsive to usual of preventive measures.

We postulated that frequent hypotensive episodes may lead to a noxious inflammatory response mediated by oxidative stress induced by ischemia-reperfusion. The aim of this study was therefore to analyze the effect of 20% albumin and 4% gelatin infusions on oxidative stress and microinflammatory status in hypotension-prone patients unresponsive to usual preventive measures.

Methods

Prospective cross-over study (lasting 20 weeks) of routine infusion of 200 ml of 20% albumin versus 200 ml of 4% gelatin in 10 patients with refractory intradialytic hypotension. We analyzed the effect of 20% albumin and 4% gelatin on microinflammatory status, oxidative stress, serum nitrite and nitrate levels by analysis of variance.

Results

A significant decrease in serum ceruloplasmin and serum C3 was observed during the albumin period (p < 0.05, repeated measure ANOVA). A significant decrease in serum hydrogen peroxide was seen during albumin and gelatin administration (p < 0.01, repeated measure ANOVA) and a very large decrease in serum lipid peroxides was observed during the albumin period only (p < 0.01, Friedman test). Serum lactoferrin, serum proinflammatory cytokines and serum nitrite and nitrate levels remained stable during the different periods of this pilot trial.

Conclusions

We conclude that the improvement in microinflammatory status observed during colloid infusion in hypotension-prone dialysis patients may be related to a decrease in ischemia-reperfusion of noble organs, together with a specific reduction in oxidative stress by albumin.

Trial registration

ISRCTN 20957055

Human albumin for intradialytic hypotension in haemodialysis patients

BACKGROUND

Intradialytic hypotension (IDH) occurs in 20% to 55% of haemodialysis sessions and is more frequent among patients on long-term haemodialysis. Symptomatic IDH is generally defined as a decrease in systolic blood pressure (BP) of at least 10 mm Hg or a systolic BP less than 100 mm Hg, with symptoms such as cramps, nausea, vomiting, and dizziness. IDH is managed acutely by volume expansion through the intravenous administration of fluids.

OBJECTIVES

To compare the benefits and harms of volume expansion with human albumin, alone or in combination with crystalloid or non-protein colloids, for treating IDH in haemodialysis patients.

SEARCH STRATEGY

The Cochrane Renal Group's Specialised Register and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 9) MEDLINE (1966 to Oct 2009), and EMBASE (1980 to Oct 2009) were searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs as well as randomised crossover studies were to be included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Relative risk (RR) was to be used to analyse dichotomous variables and mean difference (MD) used to analyse continuous variables.

MAIN RESULTS

One double blind randomised crossover trial met the inclusion criteria and compared 5% albumin to normal saline in patients with a previous history of IDH. Results from 45 assessable participants did not lead to rejection of the null hypothesis of no difference between 5% albumin and normal saline in the primary outcome measure of percentage target ultrafiltration achieved, nor in 11/12 secondary outcomes. Additional (unblinded) saline was given less often when 5% albumin was used compared with saline (16% versus 36%, P = 0.04). However, the volume of additional fluid administered was similar in both groups. There were no significant differences in the nursing time required to treat IDH and the time to restore BP.

AUTHORS' CONCLUSIONS

No randomised or controlled trial was identified comparing albumin to crystalloids (other than normal saline) or non-protein colloids, or a combination of both, in the treatment of symptomatic hypotension during dialysis. One double blind crossover RCT in 45 assessable patients showed that 5% albumin is not superior to normal saline for the treatment of symptomatic hypotension in maintenance haemodialysis patients with a previous history of IDH. Given the cost and relative rarity of albumin use compared to saline, saline should be first line of therapy for treatment of IDH in stable dialysis patients.

Hypertonic saline in critical care: a review of the literature and guidelines for use in hypotensive states and raised intracranial pressure

Hypertonic saline has been in clinical use for many decades. Its osmotic and volume-expanding properties make it theoretically useful for a number of indications in critical care. This literature review evaluates the use of hypertonic saline in critical care. The putative mechanism of action is presented, followed by a narrative review of its clinical usefulness in critical care. The review was conducted using the Scottish Intercollegiate Guidelines Network method for the review of cohort studies, randomised-controlled trials and meta-analyses. The review focuses specifically on blood pressure restoration and outcome benefit in both haemorrhagic and non-haemorrhagic shock, and the management of raised intracranial pressure. Issues of clinical improvement and outcome benefit are addressed. Hypertonic saline solutions are effective for blood pressure restoration in haemorrhagic, but not other, types of shock. There is no survival benefit with the use of hypertonic saline solutions in shock. Hypertonic saline solutions are effective at reducing intracranial pressure in conditions causing acute intracranial hypertension. There is no survival or outcome benefit with the use of hypertonic saline solutions for raised intracranial pressure. Recommendations for clinical use and future directions of clinical research are presented.

Changes in the volume status of haemodialysis patients are reflected in sublingual microvascular perfusion

BACKGROUND

After the introduction of sidestream darkfield imaging (SDF) of the microcirculation, it has become clear that in sepsis, microcirculatory alterations can exist in the absence of systemic haemodynamic abnormalities. However, it is unclear whether this phenomenon also occurs in the treatment of end-stage kidney disease (ESKD) where alterations in the volume status of patients occur during dialysis. We tested the hypothesis that volume changes during dialysis directly affect the perfusion of the microcirculation in a group of adult haemodialysis patients. Secondly, we evaluated microcirculatory response to autotransfusion using the Trendelenburg position (TP).

METHODS

Patients who were on chronic intermittent haemodialysis were assessed for sublingual microvascular flow by SDF imaging pre- and post-TP, performed before and after ultrafiltration (UF). Sublingual microvascular flow was estimated using a semi-quantitative microvascular flow index (MFI) in small (diameter <25 microm, which includes capillaries), medium (25-50 microm) and large-sized (50-100 microm) microvessels (no flow: 0, intermittent flow: 1, sluggish flow: 2 and continuous flow: 3). Changes were evaluated with the non-parametric paired Wilcoxon test. P < 0.05 was judged to indicate a significant difference.

RESULTS

Thirty-nine adult patients took part in the study. The underlying diseases causing ESKD were predominantly hypertension (HT, n = 10), diabetes mellitus (DM, n = 7) or both (n = 3). At the start of UF, microvascular flow did not change significantly by TP. After completion of UF, MFI had decreased significantly in all types of microvessels (P < 0.001). After UF (median volume extraction 2.49l), MFI was lower than that at the start of UF and increased in most patients after TP (P < 0.001) in all categories of vessels. Changes were most prominent in the smallest microvessels.

CONCLUSIONS

Sublingual microvascular perfusion is reduced by UF and can be restored temporarily using autotransfusion by TP due to increased venous return. SDF imaging is able to detect these volume changes. SDF imaging and TP could become a useful bedside tool to evaluate the patient's (microvascular) volume status and response to therapy in dialysis or intradialytic hypotension.

Small-volume resuscitation with hyperoncotic albumin: a systematic review of randomized clinical trials

Background

Small-volume resuscitation can rapidly correct hypovolemia. Hyperoncotic albumin solutions, long in clinical use, are suitable for small-volume resuscitation; however, their clinical benefits remain uncertain.

Methods

Randomized clinical trials comparing hyperoncotic albumin with a control regimen for volume expansion were sought by multiple methods, including computer searches of bibliographic databases, perusal of reference lists, and manual searching. Major findings were qualitatively summarized. In addition, a quantitative meta-analysis was performed on available survival data.

Results

In all, 25 randomized clinical trials with a total of 1,485 patients were included. In surgery, hyperoncotic albumin preserved renal function and reduced intestinal edema compared with control fluids. In trauma and sepsis, cardiac index and oxygenation were higher after administration of hydroxyethyl starch than hyperoncotic albumin. Improved treatment response and renal function, shorter hospital stay and lower costs of care were reported in patients with liver disease receiving hyperoncotic albumin. Edema and morbidity were decreased in high-risk neonates after hyperoncotic albumin administration. Disability was reduced by therapy with hyperoncotic albumin in brain injury. There was no evidence of deleterious effects attributable to hyperoncotic albumin. Survival was unaffected by hyperoncotic albumin (pooled relative risk, 0.95; 95% confidence interval 0.78 to 1.17).

Conclusion

In some clinical indications, randomized trial evidence has suggested certain benefits of hyperoncotic albumin such as reductions in morbidity, renal impairment and edema. However, further clinical trials are needed, particularly in surgery, trauma and sepsis.

Influence of fluid resuscitation on renal microvascular PO2 in a normotensive rat model of endotoxemia

Introduction

Septic renal failure is often seen in the intensive care unit but its pathogenesis is only partly understood. This study, performed in a normotensive rat model of endotoxemia, tests the hypotheses that endotoxemia impairs renal microvascular PO₂ (μPO₂) and oxygen consumption (VO_2,ren), that endotoxemia is associated with a diminished kidney function, that fluid resuscitation can restore μPO₂, VO_2,ren and kidney function, and that colloids are more effective than crystalloids.

Methods

Male Wistar rats received a one-hour intravenous infusion of lipopolysaccharide, followed by resuscitation with HES130/0.4 (Voluven^®), HES200/0.5 (HES-STERIL^{® ®} 6%) or Ringer's lactate. The renal μPO₂ in the cortex and medulla and the renal venous PO₂ were measured by a recently published phosphorescence lifetime technique.

Results

Endotoxemia induced a reduction in renal blood flow and anuria, while the renal μPO₂ and VO_2,ren remained relatively unchanged. Resuscitation restored renal blood flow, renal oxygen delivery and kidney function to baseline values, and was associated with oxygen redistribution showing different patterns for the different compounds used. HES200/0.5 and Ringer's lactate increased the VO_2,ren, in contrast to HES130/0.4.

Conclusion

The loss of kidney function during endotoxemia could not be explained by an oxygen deficiency. Renal oxygen redistribution could for the first time be demonstrated during fluid resuscitation. HES130/0.4 had no influence on the VO_2,ren and restored renal function with the least increase in the amount of renal work.

Effect of a newly developed charging chamber for the treatment of hypotension during hemodialysis

We developed a new method of hemodialysis using a charging chamber for treatment of hemodialysis patients with hypotension occurring during the latter half of hemodialysis (collapse). The purpose of this method was to recover systolic blood pressure (BP) by returning a part of blood within the chamber into the body circulation when hemodialysis collapse occurred. Using this method, systolic BP recovery (DeltaBP) in ten hemodialysis patients (4 males, 6 females, mean age 66.0 years old) was compared to a control group treated with intravenous administration of 20 ml of 10% NaCl. When hemodialysis collapse occurred, 60 ml of blood within the chamber in this method and 20 ml of 10% NaCl intravenously in the control group were administered and systolic BP was measured 20 minutes later. The results showed that DeltaBP using this method was 26.0 mm Hg (ANOVA: p = 0.0072), while in the control group it was 30.2 mm Hg (ANOVA: p = 0.0003), and there was no significant difference between the systolic BP recovery of both groups (paired t test: p = 0.4196).

Albumin in critical care: SAFE, but worth its salt?

Intravascular fluid therapy is a common critical care intervention. However, the optimal type of resuscitation fluid, crystalloid or colloid, remains controversial. Despite the many theoretical benefits of human albumin administration in critically ill patients, there has been little evidence to support its widespread clinical use. Previous systematic reviews have led to conflicting results regarding the safety and efficacy of albumin. The recently reported Saline versus Albumin Evaluation study has provided conclusive evidence that 4% albumin is as safe as saline for resuscitation, although no overall benefit of albumin use was seen. Subgroup analysis of the albumin-treated group revealed a trend towards decreased mortality in patients with septic shock, and a trend towards increased mortality in trauma patients, especially those with traumatic brain injury. The results of these subgroups, as well as the use of higher albumin concentrations and other synthetic colloids (dextrans, starches), require rigorous evaluation in clinical trials. Finally, the Saline versus Albumin Evaluation trial represents a methodological milestone in critical care medicine, due to its size, its efficient trial design, and its logistical coordination. Future studies are still required, however, to establish a therapeutic niche for albumin and other colloids.

Clinical case-based approach to understanding intradialytic hypotension

The approach to end-stage renal disease (ESRD) patients who develop intradialytic hypotension (IDH) encompasses an understanding of the pathophysiology, appropriate dialysis prescription modification, application of newer pharmacologic therapies, and development of strategies for prevention. Patients should have a "minimal data set" as part of their predialysis assessment. This information is critical to prescription modifications that may help decrease the risk for IDH. Individuals at "high risk" for IDH should be kept to a "safe zone" for dialysis ultrafiltration (</=3% of body weight). Specific maneuvers that may decrease the risk for IDH include adjustment of the dialysate sodium or calcium concentration and dialysate temperature. The first priority for patients developing IDH should be the stabilization of the blood pressure and improvement in the patient's symptomology. Pharmacologic intervention should be considered for patients who require repeat interventions for IDH. "At-risk" patients with a strong cardiac history should undergo an assessment of their cardiovascular status if IDH episodes occur. The use of pharmacologic therapy, ie, midodrine, alone or in combination with prescription modification, can be helpful in decreasing interventions required for IDH. Noncompliance and high interdialytic weight gain in the setting of left ventricular hypertrophy (LVH) and diastolic dysfunction can increase the risk of IDH. Assessment of antihypertensive medications should be performed on a regular basis to determine the correct dosing schedule for patients with hypertension who develop IDH. Coronary flow reserve may be compromised in patients with LVH, adding to the risk for perfusion injury with low blood pressure. Increasing the dialysate calcium concentration may decrease the incidence of arrhythmogenicity in certain patients. Patients with low body temperature may benefit most from cool dialysate. Unit personnel should be aware of the potential link between hypotension and the increased relative risk for death in ESRD patients. Clinical training sessions on IDH risk recognition and appropriate treatment should be implemented within the dialysis unit. Because repeated bouts of IDH can be disruptive to the smooth efficiency of unit operations, attention to prevention as well as acute intervention of IDH is important. Preventive strategies can be developed in each unit to decrease the number of future IDH events. Considering the importance of hypotension in overall patient survival, attention to identifying the percentage of patients in each unit who experience IDH and/or who present with low blood pressure (systolic <110 mm Hg) should be tracked as a quality assurance initiative.

Implications for the role of endogenous nitric oxide inhibitors in hemodialysis hypotension

Hypotensive episodes during hemodialysis in patients with end-stage renal disease in the absence of inadequate maintenance of the plasma volume, pre-existence of cardiovascular disease, or autonomic nervous system dysfunction is accompanied by increase in the plasma concentrations of the end-products of nitric oxide metabolism, above the levels expected based on the reduction of urea. Factors that can influence the synthesis of nitric oxide or the regulation of the effects of this free radical in patients with chronic renal failure are reviewed. Convergence of these factors and their interactions during the hemodialysis procedure are discussed as the basis for the generation of excessive amounts of nitric oxide that serves as an important contributing factor in the development of symptomatic hypotension.