BackgroundThe monitoring of dialysate ultraviolet (UV) absorbance is a validated technology to measure hemodialysis adequacy and allows for continuous and real-time tracking every session as opposed to the typical once-monthly assessments. Clinical care guidelines are needed to interpret the findings so as to troubleshoot problematic absorbance patterns and intervene during an individual treatment as needed.MethodsWhen paired with highly structured clinical care protocols that allow autonomous nursing actions, this technology has the potential to improve treatment outcomes. These devices measure the UV absorbance of dialysate solutes to calculate and then display the delivered as well as predicted clearance for that session. Various technical factors can affect the course of dialysate absorbance, confound the device’s readout of clearance results and thus lead to challenges for the dialysis unit staff to properly monitor dialysis adequacy. We analyze optimal and problematic patterns to the device’s ‘clearance’ display (e.g. due to thrombosis of hollow fibers, inadequate access blood flow or recirculation) and provide specific interventions to ensure delivery of an adequate dialysis dose. A rigorous algorithm is presented with representative device monitor display profiles from actual hemodialysis sessions. Procedural rationale and interventions are described for each individual scenario.ConclusionReal-time hemodialysate UV absorbance patterns can be used for protocol-based intradialytic interventions to optimize solute clearance.

Hyperkalemia occurs frequently in hospitalized patients and is of particular concern for those who have undergone surgery, with postoperative care provided by clinicians of many disciplines. This review describes the normal physiology and how multiple perioperative factors can disrupt potassium homeostasis and lead to severe elevations in plasma potassium concentration. The pathophysiologic basis of diverse causes of hyperkalemia was used to broadly classify etiologies into those with altered potassium distribution (e.g. increased potassium release from cells or other transcellular shifts), reduced urinary excretion (e.g. reduced sodium delivery, volume depletion, and hypoaldosteronism), or an exogenous potassium load (e.g. blood transfusions). Surgical conditions of particular concern involve: rhabdomyolysis from malpositioning, trauma or medications; bariatric surgery; vascular procedures with tissue ischemia; acidosis; hypovolemia; and volume or blood product resuscitation. Certain acute conditions and chronic co-morbidities present particular risk. These include chronic kidney disease, diabetes mellitus, many outpatient preoperative medications (e.g. beta blockers, salt substitutes), and inpatient agents (e.g. succinylcholine, hyperosmolar volume expanders). Clinicians need to be aware of these pathophysiologic mechanisms for developing perioperative hyperkalemia as many of the risks can be minimized or avoided.

With media focus on benefits from reducing sodium intake, there is increased popularity of salt substitutes, typically potassium chloride. While viewed by the public as a healthy alternative to standard table salt, less appreciated is the severe risk with certain comorbidities and medications. We report the case of an elderly female with chronically high salt substitute intake, normal renal function, diabetes, hypertension treated with angiotensin-converting enzyme inhibitor and beta blockade, who developed life-threatening hyperkalemia after a minimally invasive outpatient procedure. We describe the pathophysiology of the disruption in potassium homeostasis and emphasize the importance of dietary history and educating high-risk patients to avoid salt substitutes.

SUMMARY Background Identifying erythropoiesis‐stimulating agent (ESA) resistance is important for treating reversible causes, reaching target haemoglobin levels with minimal dosing, avoiding adverse effects and reducing costs. The resistance index (RI, dose/kg weight/g haemoglobin/dl) is reportedly superior to absolute or weight‐based dosing. Objectives With the growing number of ESA classes and medications, our goal was to develop methodology to establish RI ranges in otherwise healthy haemodialysis patients as a structured approach to identify remediable causes of anaemia. Design We retrospectively studied anaemia management with darbepoetin in 100 chronic haemodialysis patients and a subgroup of 48 without identifiable conditions that impair erythropoiesis. Data included inflammatory and bone marrow conditions, medications with hematologic effects, catheter use, iron, parathyroid and dialysis measures. Results The haematologically healthy group was aged 57.1 ± 1.9 SEM years, 33% diabetic, with haemoglobin 10.4 ± 0.2 g/dl. The darbepoetin RI (DRI) values were 0.05 ± 0.01, absolute dose 38.5 ± 3.5 mcg/week and weight‐based 0.50 ± 0.05 mcg/kg. Regression analyses included iron saturation, ferritin, parathyroid hormone and urea reduction ratio. DRI was superior to other dosing approaches based on the distribution of results (kurtosis) and discordance between the measures that occurred in 17% of patients at haemoglobin target. Conclusions We demonstrate the value of determining the RI for use with expanding ESA choices, using as an example how DRI values can be established for healthy haemodialysis patients so as to guide dosing. When elevated, the RI can trigger evaluation for remediable factors causing hyporesponsiveness even when haemoglobin goals have been reached.

A new method to image and quantify intra-abdominal haemorrhage using electrical impedance tomography (EIT) was tested in vivo. Supine peritoneal dialysis patients were monitored using an 8-electrode hemiarray placed on the anterior abdomen. EIT measurements were recorded using the EPack II data acquisition system before, during, and after the administration of dialysate. The amount of dialysate infused was recorded synchronous with EIT measurements and used as a control. Tomographic images of impedance change were reconstructed using a weighted, sensitivity-based method and then post-processed to obtain a quantitative estimate of the total dialysate volume added and the rate of dialysate administration. Our preliminary study included two subjects, one male and one female, each of whom participated for two sessions spaced about 6 months apart. Data collected from these sessions indicated that with an in vivo SNR of about 35 dB the EPack II can detect accumulations larger than about 100 ml, with a quantification uncertainty of about 50 ml. The rate of accumulation was determined in less than 2 min. This method shows promise for automated detection of other pathologies, eg ascites, and is adaptable to detecting conductive accumulations in other anatomy.