Hypokalaemia and hyperkalaemia

Hyperkalemia burden and treatment patterns in Chinese patients on hemodialysis: final analysis of a prospective multicenter cohort study (PRECEDE-K)

OBJECTIVES

Patients with end-stage renal disease (ESRD) on hemodialysis (HD) are at risk for hyperkalemia (HK), associated with cardiac arrhythmia and sudden death. Data on the burden of HK and management techniques among HD patients in China are still scarce. This study assessed the treatment modalities, recurrence, and prevalence of HK in Chinese HD patients.

METHODS

In this prospective cohort study conducted from May 2021 to July 2022, patients aged ≥18 years who had ESRD and were on HD were enrolled from 15 centers in China (up to 6 months).

RESULTS

Overall, 600 patients were enrolled. At the baseline visit, mean (± standard deviation) urea reduction ratio was 68.0% ± 9.70 and Kt/V was 1.45 ± 0.496. Over 6 months, 453 (75.5%) patients experienced HK, of whom 356 (78.6%) recurred. Within 1, 2, 3, 4, 5, and 6 months, 203 (44.8%), 262 (57.8%), 300 (66.2%), 326 (72.0%), 347 (76.6%), and 356 (78.6%) patients had at least one HK recurrence event, respectively. The proportions of patients with ≥1, 2, 3, 4, 5, or 6 HK recurrence events were 356 (78.6%), 306 (67.5%), 250 (55.2%), 208 (45.9%), 161 (35.5%), and 110 (24.3%), respectively. Among the 453 patients who experienced HK, only 24 (5.3%) were treated with potassium binders: seven (1.5%) with sodium polystyrene sulfonate, 13 (2.9%) with calcium polystyrene sulfonate, and six (1.3%) with sodium zirconium cyclosilicate.

CONCLUSION

Since HK is a chronic illness, long-term care is necessary. Patients on HD should have effective potassium management on non-dialysis days, yet our real-world population rarely used potassium binders.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04799067.

Heart Failure and Edema Costs in Patiromer and Sodium Zirconium Cyclosilicate Users

Key Points

Prior research suggests differences in rates of heart failure hospitalization or serious emergency department visits between patients on patiromer versus sodium zirconium cyclosilicate. Total costs of heart failure–related hospitalizations and emergency department visits may be lower in patients on patiromer compared with sodium zirconium cyclosilicate.

Background

Previous work suggested differences between patients taking patiromer or sodium zirconium cyclosilicate (SZC) in real-world risk of heart failure (HF) hospitalizations and edema hospitalizations or emergency department (ED) visits (edema events). We further investigated these differences to assess economic importance. Retrospective study using published event rates and mean costs derived from Optum's deidentified Clinformatics Data Mart Database.

Methods

We designed a model to estimate adjusted economic offsets that combined respective patiromer and SZC HF hospitalization (25.1 and 35.8; difference 10.7 [95% confidence interval (CI)2, 2.6 to 18.8]) and edema event (3.4 and 7.1; difference 3.6 [95% CI, 1.7 to 7.1]) rates/100 person-years from the original published work with costs from our parallel data extract spanning 2019–2021, adjusted to 2021 US dollars.

Results

In a base case of mean HF hospitalization, edema event, and 30-count potassium-binder prescription costs from our data extract, the estimated mean savings with patiromer was $1428 per person per year (95% CI, −$1508 to $4652). Respective costs per person per year for patiromer versus SZC were $8526 versus $12,622 (difference $4096 [95% CI, $116 to $7320]) for HF hospitalization and edema events, and $10,649 versus $7981 (difference −$2668) for potassium binders, totaling $19,175 for patiromer versus $20,603 for SZC.

Conclusions

With differing drug costs, hospitalization and ED costs offset this difference when event rates were numerically small. Model outcomes were driven by HF hospitalization cost and least influenced by edema ED visit cost. A limitation was that the Clinformatics Data Mart data extract may differ from the original work.

Epidemiology and risk factors for hyperkalaemia in heart failure

Patients with heart failure (HF), particularly those with impaired renal function receiving renin-angiotensin-aldosterone system inhibitors (RAASis), are at risk of hyperkalaemia; when hyperkalaemia is severe, this can have serious clinical consequences. The incidence, prevalence, and risk factors for hyperkalaemia reported in randomized trials of RAASis may not reflect clinical practice due to exclusion of patients with elevated serum potassium (sK+) or severe renal impairment: information on patients managed in routine clinical care is important to understanding the actual burden of hyperkalaemia. This paper reviews the available clinical epidemiology data on hyperkalaemia in HF and considers areas requiring further research. Observational studies published since 2017 that focused on hyperkalaemia, included patients with HF, and had ≥1000 participants were considered. Hyperkalaemia occurrence in HF varied widely from 7% to 39% depending on the setting, HF severity, follow-up length, and concomitant medications. Rates were lowest in patients with newly diagnosed HF and highest in patients with greater disease severity; comorbidities, such as chronic kidney disease and diabetes, and RAASi use, reflected commonly identified risk factors for hyperkalaemia in patients with HF. Hyperkalaemia was most often mild; however, from the limited data available, persistence of mild hyperkalaemia was associated with an increased risk of mortality and major adverse cardiovascular events. There were also limited data available on the progression of hyperkalaemia. Recurrence was common, occurring in one-quarter to two-fifths of hyperkalaemia cases. Despite HF guidelines recommending close monitoring of sK+, 55-93% of patients did not receive appropriate testing before or after initiation of RAASi or in follow-up to moderate/severe hyperkalaemia detection. Many of the observational studies were retrospective and from a single country. There is a need for international, prospective, longitudinal, observational studies, such as the CARE-HK in HF study (NCT04864795), to understand hyperkalaemia's prevalence, incidence, and severity; to identify and characterize cases that persist, progress, and recur; to highlight the importance of sK+ monitoring when using RAASi; and to assess the impact of newer HF therapies and potassium binders in clinical practice. Data from both clinical trials and observational studies with adjustments for confounding variables will be needed to assess the contribution of hyperkalaemia to clinical outcomes.

Prevalence and Factors Associated with Potassium Abnormalities Among Outpatients with Heart Failure Taking Diuretics in a Tertiary Referral Hospital in Tanzania

Background

Heart failure (HF) is a chronic progressive condition in which the heart is unable to pump enough blood to meet the body's need for blood and oxygen. Globally, about 64 million people are affected with HF. This study was undertaken to determine the magnitude and factors associated with potassium abnormalities in heart failure patients on diuretics in Tanzania.

Methods

This was a hospital based cross-sectional study conducted at Bugando Medical Centre's outpatient clinic. The selection of this hospital was driven by the significant presence of heart failure patients in the facility and the convenience for the researchers, who were stationed at this facility during the study period. All consenting adult patients aged 18 years and above that were attending the cardiac clinic and had met Framingham criteria for heart failure and were taking diuretics for at least one month were included.

Results

The prevalence of hypokalemia and hyperkalemia was found to be 4.3% And 19.3% respectively. The median (IQR) age was 61 (46-70) years and majority of them (52.8%) were females. most of the patients (87.7%) had New York Heart Association (NYHA) class III heart failure.

Conclusion

Factors associated with potassium abnormalities include medication use, kidney disease and more severe heart failure. Healthcare providers should ensure that all patients with these associated factors receive regular electrolyte testing. Electrolytes should be part of the baseline investigation to all patients with heart failure starting treatment, and should be closely monitored in every clinic visit for early detection of these abnormalities and possible intervention, including dose adjustments.

Clinical features and recovery pattern of secondary hypokalaemic paralysis

PURPOSE

Information regarding frequency, details of neurological signs and recovery patterns of patients with secondary hypokalaemic paralysis (HP) is limited. This study aimed to analyse the frequency, aetiology, clinical features and recovery patterns of patients with secondary HP.

METHODS

The clinical and laboratory records of 18 consecutive patients with secondary HP aged ≥ 18 years admitted to our hospital between April 2011 and March 2022 were reviewed. Patients with inherited hypokalaemic periodic paralysis were excluded.

RESULTS

Of the 18 patients, 16 had a common aetiology: chronic alcoholism, diarrhoea or an imbalanced diet. Initial symptoms, such as fatigue, were often atypical. Three patients had prominent asymmetric limb weakness and four had predominant upper limb weakness. On admission, the mean serum potassium and creatine kinase (CK) levels of the patients were 1.90 mmol/L and 4488 U/mL, respectively. Ten patients (56%) had decreased potassium levels after admission, despite potassium replacement treatment (rebound hypokalaemia). Twelve patients presented with increased CK levels even after 2-5 days (delayed hyperCKaemia). Low serum magnesium levels significantly correlated with rebound hypokalaemia.

CONCLUSIONS

Secondary HP can be caused by a variety of conditions, but mainly occurs due to lifestyle conditions/disorders. Secondary HP often presents with atypical symptoms, and the initial symptoms can be non-specific. Rebound hypokalaemia and delayed hyperCKaemia are common in secondary HP, despite potassium replacement. As such, careful serial monitoring is needed for patients with secondary HP.

Evaluation of safety, effectiveness and treatment patterns of sodium zirconium cyclosilicate in management of hyperkalaemia in China: a real-world study protocol

INTRODUCTION

Hyperkalaemia (HK) is a potentially life-threatening electrolyte imbalance associated with several adverse clinical outcomes. The efficacy and negative effects of currently existing treatment options have made HK management questionable. Sodium zirconium cyclosilicate (SZC), a novel highly selective potassium binder, is approved for the treatment of HK. The present study will be aimed to assess the safety, effectiveness and treatment patterns of SZC in Chinese patients with HK in a real-world clinical setting as it is required by China's drug review and approval process.

METHODS AND ANALYSIS

This is a multicentre, prospective cohort study which plans to enrol 1000 patients taking SZC or willing to take SZC from approximately 40 sites in China. Patients ≥18 years of age at the time of signing the written informed consent and with documented serum potassium levels ≥5.0 mmol/L within 1 year before study enrolment day will be included. Eligible patients will receive SZC treatment and will be followed up for 6 months from enrolment day. The primary objective will be to evaluate the safety of SZC for the management of HK in Chinese patients in terms of adverse events (AEs), serious AEs as well as discontinuation of SZC. The secondary objectives will include understanding the SZC dosage information in terms of its effectiveness and treatment patterns under real-world clinical practice and assessing effectiveness of SZC during the observational period.

ETHICS AND DISSEMINATION

This study protocol was approved by the Ethics Committee of the First Affiliated Hospital of Dalian Medical University (approval number: YJ-JG-YW-2020). All the participating sites have received the ethics approval. Results will be disseminated through national and international presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT05271266.

The Mutual Relationship among Cardiovascular Diseases and COVID-19: Focus on Micronutrients Imbalance

Micronutrients are ions and vitamins humbly required by the human body. They play a main role in several physiological mechanisms and their imbalance is strongly associated with potentially-fatal complications. Micronutrient imbalance is associated with many cardiovascular diseases, such as arrythmias, heart failure, and ischemic heart disease. It has been also observed in coronavirus disease 2019 (COVID-19), particularly in most severe patients. The relationship between cardiovascular diseases and COVID-19 is mutual: the latter triggers cardiovascular disease onset and worsening while patients with previous cardiovascular disease may develop a more severe form of COVID-19. In addition to the well-known pathophysiological mechanisms binding COVID-19 and cardiovascular diseases together, increasing importance is being given to the impact of micronutrient alterations, often present during COVID-19 and able to affect the balance responsible for a good functioning of the cardiovascular system. In particular, hypokalemia, hypomagnesemia, hyponatremia, and hypocalcemia are strongly associated with worse outcome, while vitamin A and D deficiency are associated with thromboembolic events in COVID-19. Thus, considering how frequent the cardiovascular involvement is in patients with COVID-19, and how it majorly affects their prognosis, this manuscript provides a comprehensive review on the role of micronutrient imbalance in the interconnection between COVID-19 and cardiovascular diseases.

Preoperative hypokalemia can increase complications after colorectal cancer surgery: a propensity score matching analysis

Background

Whether hypokalemia can affect the short-term outcomes of CRC patients after radical surgery remains unclear. The purpose of this study was to investigate the impact of preoperative hypokalemia on the short-term outcomes for colorectal cancer (CRC) patients who underwent radical CRC surgery using propensity score matching (PSM).

Methods

We retrospectively enrolled consecutive CRC patients from Jan 2011 to Dec 2021 in a single-center hospital. Hypokalemia was defined as a serum potassium concentration < 3.5 mmol/L. The short-term outcomes were compared between the hypokalemia group and the normal blood potassium group. In addition, univariate and multivariate logistic regression analyses were conducted to identify independent risk factors for overall complications.

Results

A total of 6183 CRC patients who underwent radical surgery were included in this study, of whom 390 (6.3%) patients were diagnosed with hypokalemia before surgery. After 1:1 ratio PSM, there were 390 patients in the hypokalemia group and in the normal potassium group. No significant difference was found between the two groups after PSM in terms of baseline information (p > 0.05). Regarding short-term outcomes, the hypokalemia group had a longer hospital stay (p = 0.028), a higher proportion of overall complications (p = 0.048) and a higher incidence of postoperative pneumonia (p = 0.008) after PSM. Moreover, hypokalemia (p = 0.036, OR = 1.291, 95% CI = 1.017–1.639) was an independent risk factor for overall complications.

Conclusion

Preoperative hypokalemia could increase complications after CRC surgery and prolong the hospital stay. Moreover, preoperative hypokalemia was an independent risk factor for overall complications.

Arrhythmogenic Mechanisms in Hypokalaemia: Insights From Pre-clinical Models

Potassium is the predominant intracellular cation, with its extracellular concentrations maintained between 3. 5 and 5 mM. Among the different potassium disorders, hypokalaemia is a common clinical condition that increases the risk of life-threatening ventricular arrhythmias. This review aims to consolidate pre-clinical findings on the electrophysiological mechanisms underlying hypokalaemia-induced arrhythmogenicity. Both triggers and substrates are required for the induction and maintenance of ventricular arrhythmias. Triggered activity can arise from either early afterdepolarizations (EADs) or delayed afterdepolarizations (DADs). Action potential duration (APD) prolongation can predispose to EADs, whereas intracellular Ca²⁺ overload can cause both EADs and DADs. Substrates on the other hand can either be static or dynamic. Static substrates include action potential triangulation, non-uniform APD prolongation, abnormal transmural repolarization gradients, reduced conduction velocity (CV), shortened effective refractory period (ERP), reduced excitation wavelength (CV × ERP) and increased critical intervals for re-excitation (APD-ERP). In contrast, dynamic substrates comprise increased amplitude of APD alternans, steeper APD restitution gradients, transient reversal of transmural repolarization gradients and impaired depolarization-repolarization coupling. The following review article will summarize the molecular mechanisms that generate these electrophysiological abnormalities and subsequent arrhythmogenesis.

Hyperkalemic Emergency: When You Have Taken a Few Too Many KCl Tablets

Hyperkalemia is a common clinical problem that varies significantly in severity and indications for treatment. Hyperkalemic emergency exists when there are clinical signs or symptoms, including cardiac conduction abnormalities. The combination of nebulized albuterol and insulin with glucose is most effective for managing clinically significant hyperkalemia. Prompt recognition of hyperkalemic emergency, immediate interventions to lower extracellular potassium, and involvement of multiple disciplines (including critical care and nephrology) are essential to addressing this life-threatening presentation.

Midazolam Alters Acid-Base Status Less than Azaperone during the Capture and Transport of Southern White Rhinoceroses (Ceratotherium simum simum)

Acidemia represents a major life-threatening factor during rhinoceros capture. The acid-base status during rhinoceros transport is unknown. The purpose of this study was to describe changes in acid-base status during rhinoceros capture and transport and compare these changes between rhinoceroses sedated with azaperone or midazolam. Twenty-three wild white rhinoceros bulls were road-transported 280 km for reasons unrelated to this study. Rhinoceroses were captured with etorphine-azaperone (Group A) or etorphine-midazolam (Group M). During transport, azaperone (Group A) or midazolam (Group M) was re-administered every 2 h and venous blood collected. Changes in blood pH and associated variables were compared over time and between groups using a general linear mixed model. Rhinoceroses of both groups experienced a respiratory and metabolic acidosis during capture (pH 7.109 ± 0.099 and 7.196 ± 0.111 for Group A and Group M, respectively) that was quickly compensated for by the start of transport (pH 7.441 ± 0.035 and 7.430 ± 0.057) and remained stable throughout the journey. Rhinoceroses from Group M showed a smaller decrease in pH and associated variables at capture than rhinoceroses from Group A (p = 0.012). The use of midazolam instead of azaperone could therefore improve the success of rhinoceros capture and thus, contribute to the outcome of important conservation translocations.

Comparative Study of Constipation Exacerbation by Potassium Binders Using a Loperamide-Induced Constipation Model

Patients on dialysis are frequently administered high doses of potassium binders such as calcium polystyrene sulfonate (CPS) and sodium polystyrene sulfonate (SPS), which exacerbate constipation. Here, we compare the degree of constipation induced by CPS and SPS using a loperamide-induced constipation model to identify the safer potassium binder. Constipation model was created by twice-daily intraperitoneal administration (ip) of loperamide hydrochloride (Lop; 1 mg/kg body weight) in rats for 3 days. Rats were assigned to a control group, Lop group, Lop + CPS group or Lop + SPS group, and a crossover comparative study was performed. Defecation status (number of feces, feces wet weight, fecal water content and gastrointestinal transit time (GTT)) was evaluated. In the Lop + CPS group, GTT was significantly longer, and fecal water content was reduced. In the Lop + SPS group—although the fecal water content and GTT were unaffected—the number of fecal pellets and the fecal wet weight improved. Thus, SPS was less likely to cause constipation exacerbation than CPS. Considering the high frequency of constipation in dialysis patients with hyperkalemia, preferentially administering SPS over CPS may prevent constipation exacerbation.

Metabolic alkalosis is related to delayed response to treatment of hypokalemia in non-surgical critically ill patients

Background: Potassium (K+) homeostasis is closely related to acid - base disorders. The aim of this study is to analyze the possible causes of hypokalemia non-surgical critically ill patients including acid - base disorders and its relationship with response to K+ supplementation. Methods: We performed a retrospective cohort study of 122 consecutive non-surgical patients admitted to the Intensive Care Unit during July 2016 Patients were classified according to the presence of hypokalemia or not. Demographic data, morbidities associated with hypokalemia, with emphasis in acid-base disorders and response to treatment were described and analyzed. Results: Hypokalemia was observed in 32,7% (n = 40) of the patients included. Hypokalemic group had a higher value of base excess (median of -0.65 [IQR -3.3-5.2] Vs -3.2 [IQR -5.1--1.4]; p < 0.001). The patients with hypokalemia that achieved normal serum K+ in more than 25 h had a higher value of excess base than those who did so in less than 24 h (median of 4.3 [IQR -2.1-5.5] vs -1.9 [IQR -4.8-3]; p < 0.05). Neither the degree of hypokalemia, the time to development, route of administration or solution concentration, speed of infusion, the amount of K+ administered per day per kg of weight were related with the response of treatment. Conclusions: Hypokalemia is a common disorder in non-surgical critically ill patients. Hypokalemic patients had a higher incidence of metabolic alkalosis. Patients with hypokalemia and metabolic alkalosis needed a higher amount of potassium administration and higher time to achieve correction.

A Study of the Change in Sodium and Potassium Ion Concentrations in Stored Donor Blood and Their Effect on Electrolyte Balance of Recipients

Background

Preserved blood cells undergo progressive structural and functional changes that may affect their function, integrity, and viability after transfusion. The impact of transfusion of stored blood on potassium, sodium, or acid-base balance in the recipient may be complex, but information on it is inconsistent. This study therefore sought to determine the changes in the potassium and sodium levels in whole blood stored at 4°C for 28 days and clinical outcomes when such blood are transfused.

Methods

Whole blood were taken into double CPDA-1 bags and 50 ml transferred into the satellite bags for the study. Electrolyte concentration determinations were made on each of the blood sample on days 0, 7, 14, 21, and 28 using the Vitalab Selectra Junior chemistry analyser. The remaining blood in the main bags was transfused after the 28-day period, and biochemical analysis carried out on the patients before and after the transfusion. One-way ANOVA was used for the analysis of variance between the weekly ion concentrations and independent sample Mann-Whitney U test for the data obtained from the patients.

Results

The mean potassium level of all the samples started with a normal value of 3.45 mmol/L on the first day followed by a sharp rise to 9.40 mmol/L on day 7, 13.40 mmol/L on day 14, 14.60 mmol/L on day 21, and 15.40 mmol/L on day 28. Sodium on the other hand started with a high value of 148.4 mmol/L on day 0 and then reduced to 146.4 mmol/L on day 7, 140.8 mmol/L on day 14, 135.6 mmol/L on day 21, and a low value of 130.8 mmol/L on day 28. No adverse clinical outcomes were seen in patients after they were transfused with the blood.

Conclusion

It can be deduced that potassium concentration in refrigerated blood increases, whilst sodium concentration reduces with time and when such blood is transfused, it may not result in any adverse clinical outcome.

Efficiency evaluation and safety monitoring of tailored rapid potassium supplementation strategy for fatal severe hypokalemia

Stringent regulations have been established for the intravenous administration of potassium to avoid hyperkalemia in the clinic. The standard approach, however, often does not work well for treating severe hypokalemia. In the present study, a rabbit model of hyperkalemia was used to develop an tailored rapid potassium supplementation strategy and the effectiveness and safety of this new strategy were assessed. A total of 20 rabbits with induced severe hypokalemia were randomly divided into two equal treatment groups. All of the animals were injected with 3% KCl through the auricular marginal veins by a micro-injection pump; the target serum potassium concentration was 4 mmol/l. The conventional treatment group was administered a continued potassium infusion at the standard infusion rate of 0.4 mmol/kg/h. The tailored rapid supplementation group was treated in two steps: First, a loading dose of potassium was rapidly injected for 5 min and this step was repeated until the serum potassium concentration was increased to 3.5 mmol/l. After this increase in serum potassium concentration, a sustained potassium infusion at a constant dose was performed. Electrocardiogram, blood pressure, respiratory rate, serum potassium concentration, urine volume and vital signs were monitored in real-time. No hyperkalemia occurred in any of the two the groups. However, compared with the conventional group, the tailored rapid group had a significantly shorter duration of potassium infusion and arrhythmia, and a higher survival rate. In conclusion, these results demonstrate that the tailored rapid potassium supplementation strategy shortened the time of hypokalemia and is a safe and better treatment option to remedy life-threatening arrhythmia caused by severe hypokalemia with a high success rate.

Genetically encoded fluorescent indicators for imaging intracellular potassium ion concentration

Potassium ion (K+) homeostasis and dynamics play critical roles in biological activities. Here we describe three genetically encoded K+ indicators. KIRIN1 (potassium (K) ion ratiometric indicator) and KIRIN1-GR are Förster resonance energy transfer (FRET)-based indicators with a bacterial K+ binding protein (Kbp) inserting between the fluorescent protein FRET pairs mCerulean3/cp173Venus and Clover/mRuby2, respectively. GINKO1 (green indicator of K+ for optical imaging) is a single fluorescent protein-based K+ indicator constructed by insertion of Kbp into enhanced green fluorescent protein (EGFP). These indicators are suitable for detecting K+ at physiologically relevant concentrations in vitro and in cells. KIRIN1 enabled imaging of cytosolic K+ depletion in live cells and K+ efflux and reuptake in cultured neurons. GINKO1, in conjunction with red fluorescent Ca2+ indicator, enable dual-color imaging of K+ and Ca2+ dynamics in neurons and glial cells. These results demonstrate that KIRIN1 and GINKO1 are useful tools for imaging intracellular K+ dynamics.

Prevalence and risk factors for hypokalemia in patients scheduled for laparoscopic colorectal resection and its association with post-operative recovery

Background

Perioperative serum potassium levels are closely associated with postoperative clinical outcomes after gastrointestinal surgery. The aim of our retrospective study was to identify the prevalence and risk factors for preoperative hypokalemia (before pneumoperitoneum) and to evaluate the influence of preoperative hypokalemia on the recovery of postoperative gastrointestinal function.

Methods

In this retrospective study, patients scheduled for laparoscopic colorectal resection from November 11 2014 to October 20 2016, were considered for inclusion. A blood potassium level between 3.5 and 5.5 mmol/L was defined as normal, with levels between 3.0 to 3.5 mmol/L, 2.5 to 3.0 mmol/L and < 2.5 mmol/L considered as slight, moderate, and severe level of hypokalemia. The factors including age, gender, ASA grade, BMI, hypertension, diabetes, anti-hypertension drugs, lactose oral soluble, oral cathartics, oral cathartics, cathartic enemas, and blood potassium level before gastrointestinal preparation which might be associated with blood potassium level before pneumoperitoneum were analysed. The time to postoperative first flatus (FFL) and first feces (FFE) was compared between patients with and without hypokalemia.

Results

The final analysis was based on the data of 108 patients. Hypokalemia was identified in 70.37% patients, with the following distribution of blood potassium levels before pneumoperitoneum: slight, 49 (45.37%) patients; moderate, 23 (21.30%); and severe, 4 (3.70%) patients. Hypokalemia was significantly associated with hypertension and the use of ≥2 types of oral cathartics for preoperative gastrointestinal preparation. With treatment, potassium levels recovered to normal levels in all patients within 48 h postoperatively. Hypokalemia was associated with a longer postoperative time to first feces, compared to patients with a normal potassium level before pneumoperitoneum.

Conclusions

Our findings underlie the importance of early monitoring and management of serum potassium levels in these patients.

Kir2.1 channels set two levels of resting membrane potential with inward rectification

Strong inward rectifier K⁺ channels (Kir2.1) mediate background K⁺ currents primarily responsible for maintenance of resting membrane potential. Multiple types of cells exhibit two levels of resting membrane potential. Kir2.1 and K2P1 currents counterbalance, partially accounting for the phenomenon of human cardiomyocytes in subphysiological extracellular K⁺ concentrations or pathological hypokalemic conditions. The mechanism of how Kir2.1 channels contribute to the two levels of resting membrane potential in different types of cells is not well understood. Here we test the hypothesis that Kir2.1 channels set two levels of resting membrane potential with inward rectification. Under hypokalemic conditions, Kir2.1 currents counterbalance HCN2 or HCN4 cation currents in CHO cells that heterologously express both channels, generating N-shaped current-voltage relationships that cross the voltage axis three times and reconstituting two levels of resting membrane potential. Blockade of HCN channels eliminated the phenomenon in K2P1-deficient Kir2.1-expressing human cardiomyocytes derived from induced pluripotent stem cells or CHO cells expressing both Kir2.1 and HCN2 channels. Weakly inward rectifier Kir4.1 or inward rectification-deficient Kir2.1•E224G mutant channels do not set such two levels of resting membrane potential when co-expressed with HCN2 channels in CHO cells or when overexpressed in human cardiomyocytes derived from induced pluripotent stem cells. These findings demonstrate a common mechanism that Kir2.1 channels set two levels of resting membrane potential with inward rectification by balancing inward currents through different cation channels such as hyperpolarization-activated HCN channels or hypokalemia-induced K2P1 leak channels.

Palatability and physical properties of potassium-binding resin RDX7675: comparison with sodium polystyrene sulfonate

Background

Hyperkalemia is a potentially life-threatening condition that patients with heart failure or chronic kidney disease, especially those taking renin–angiotensin–aldosterone system inhibitors, are at high risk of developing. Sodium polystyrene sulfonate (SPS), a current treatment, binds potassium within the gastrointestinal tract to reduce potassium absorption. However, poor palatability limits its long-term use. RDX7675, a novel potassium binder in development for the treatment of hyperkalemia, is a calcium salt of a reengineered polystyrene sulfonate-based resin designed to have enhanced palatability. Here, the physical properties and palatability of RDX7675 and SPS are compared.

Methods

RDX7675 and SPS particle sizes were measured using wet dispersion laser diffraction. Palatability was assessed in a randomized, crossover, healthy volunteer study with two visits. At visit 1 (open label), volunteers evaluated high-viscosity, intermediate-viscosity, and water-reconstituted formulations of RDX7675 (all vanilla flavor), and an equivalent reconstituted SPS (Resonium A^®). At visit 2 (single-blind), volunteers evaluated RDX7675 as a high-viscosity formulation in vanilla, citrus, and mint flavors, and as intermediate-viscosity, low-viscosity, and reconstituted formulations in citrus flavor. Volunteers used a “sip and spit” technique to rate overall acceptability and seven individual characteristics from 1 (“dislike everything”) to 9 (“like extremely”).

Results

RDX7675 particles were smaller than SPS particles, with a narrower size range (RDX7675, 80%, 14–52 µm; SPS, 11.3–124.2 µm), and had a smooth, spherical shape, in contrast to the shard-like SPS particles. Reconstituted RDX7675 was considered superior to SPS for five of the seven palatability characteristics and for overall acceptability (median, visit 1: reconstituted RDX7675, 5.0; SPS, 4.0). High-viscosity vanilla was the most highly rated RDX7675 formulation (median overall acceptability, visit 2: 7.0).

Conclusion

The smaller, more uniformly shaped, spherical particles of RDX7675 resulted in improved palatability over SPS when reconstituted in water. The overall results are promising for future patient acceptability of RDX7675 treatment.

Long-Term Safety of Dapagliflozin in Older Patients with Type 2 Diabetes Mellitus: A Pooled Analysis of Phase IIb/III Studies

Objective

To evaluate the 104-week safety of dapagliflozin in older patients with type 2 diabetes mellitus.

Methods

Pooled analysis assessing general safety (nine phase III studies ≤104 weeks) and cardiovascular safety (21 phase IIb/III studies ≤208 weeks) by age (<65; ≥65; ≥75 years). Patients with type 2 diabetes mellitus (±background glucose-lowering therapy) received: dapagliflozin 10 mg (n = 2026) vs. placebo (n = 1956) (nine-study pool); or dapagliflozin (2.5–50 mg; n = 5936) vs. control (placebo/comparator) (n = 3403) (21-study pool).

Results

Adverse events (AEs) and discontinuations owing to AEs were more common in older vs. younger patients, and were more frequent with dapagliflozin than placebo (AEs: <65 years: 73.1 vs. 70.7 %; ≥65 years: 77.4 vs. 73.1 %; ≥75 years: 80.4 vs. 75.3 %, respectively; discontinuations: <65 years: 5.9 vs. 5.0 %; ≥65 years: 14.4 vs. 12.2 %; ≥75 years: 26.8 vs. 22.1 %, respectively); serious AE (SAE) frequency was similar (<65 years: 11.0 vs. 11.8 %; ≥65 years: 20.0 vs. 20.2 %; ≥75 years: 19.6 vs. 18.2 %, respectively). Hypoglycaemia frequency was similar across age groups and was higher with dapagliflozin than placebo (<65 years: 18.0 vs. 13.4 %; ≥65 years: 20.2 vs. 17.7 %; ≥75 years: 17.5 vs. 16.9 %, respectively); major episodes were rare. Urinary tract infection frequency was similar between treatment groups in older patients, with no increase vs. younger patients (<65 years: 8.8 vs. 5.5 %; ≥65 years: 8.1 vs. 7.6 %; ≥75 years: 8.2 vs. 9.1 %, respectively); urinary tract infection SAEs were rare. Genital infection AEs were more common with dapagliflozin, with no increase in older patients (<65 years: 8.2 vs. 1.0 %; ≥65 years: 6.6 vs. 0.9 %; ≥75 years: 7.2 vs. 0.0 %, respectively) and no SAEs. Volume reduction AEs were uncommon, with a higher frequency with dapagliflozin vs. placebo and in patients ≥75 years (<65 years: 1.7 vs. 1.2 %; ≥65 years: 2.3 vs. 1.7 %; ≥75 years: 3.1 vs. 2.6 %, respectively). Dapagliflozin did not increase the risk of fractures (<65 years: 1.1 vs. 1.1 %; ≥65 years: 1.1 vs. 2.7 %; ≥75 years: 1.0 vs. 2.6 %, respectively) or falls (<65 years: 0.7 vs. 0.7 %; ≥65 years: 0.6 vs. 2.1 %; ≥75 years: 0.0 vs. 1.3 %, respectively), regardless of age. AEs of renal function were more common with dapagliflozin than placebo and increased with age (<65 years: 3.5 vs. 2.3 %; ≥65 years: 14.0 vs. 7.9 %; ≥75 years: 29.9 vs. 20.8 %, respectively). Most were non-serious small transient increases in serum creatinine. Dapagliflozin did not increase cardiovascular risk regardless of age [hazard ratio (95 % confidence interval) vs. control: <65 years: 0.726 (0.473, 1.114); ≥65 years: 0.879 (0.565, 1.366); ≥75 years: 0.950 (0.345, 2.617), respectively].

Conclusion

Dapagliflozin treatment up to 104 weeks was well tolerated in older patients. Older dapagliflozin-treated patients had more renal AEs than placebo-treated patients; the majority of which were non-serious small transient changes in serum creatinine.

Electronic supplementary material

The online version of this article (doi:10.1007/s40266-016-0382-1) contains supplementary material, which is available to authorized users.

Kir2.1 and K2P1 channels reconstitute two levels of resting membrane potential in cardiomyocytes

KEY POINTS

Outward and inward background currents across the cell membrane balance, determining resting membrane potential. Inward rectifier K⁺ channel subfamily 2 (Kir2) channels primarily maintain the resting membrane potential of cardiomyocytes. Human cardiomyocytes exhibit two levels of resting membrane potential at subphysiological extracellular K⁺ concentrations or pathological hypokalaemia, however, the underlying mechanism is unclear. In the present study, we show that human cardiomyocytes derived from induced pluripotent stem cells with enhanced expression of isoform 1 of Kir2 (Kir2.1) channels and mouse HL-1 cardiomyocytes with ectopic expression of two pore-domain K⁺ channel isoform 1 (K2P1) recapitulate two levels of resting membrane potential, indicating the contributions of Kir2.1 and K2P1 channels to the phenomenon. In Chinese hamster ovary cells that express the channels, Kir2.1 currents non-linearly counterbalance hypokalaemia-induced K2P1 leak cation currents, reconstituting two levels of resting membrane potential. These findings support the hypothesis that Kir2 currents non-linearly counterbalance inward background cation currents, such as K2P1 currents, accounting for two levels of resting membrane potential in human cardiomyocytes and demonstrating a novel mechanism that regulates excitability.

ABSTRACT

Inward rectifier K⁺ channel subfamily 2 (Kir2) channels primarily maintain the normal resting membrane potential of cardiomyocytes. At subphysiological extracellular K⁺ concentrations or pathological hypokalaemia, human cardiomyocytes show both hyperpolarized and depolarized resting membrane potentials; these depolarized potentials cause cardiac arrhythmia; however, the underlying mechanism is unknown. In the present study, we show that inward rectifier K⁺ channel subfamily 2 isoform 1 (Kir2.1) currents non-linearly counterbalance hypokalaemia-induced two pore-domain K⁺ channel isoform 1 (K2P1) leak cation currents, reconstituting two levels of resting membrane potential in cardiomyocytes. Under hypokalaemic conditions, both human cardiomyocytes derived from induced pluripotent stem cells with enhanced Kir2.1 expression and mouse HL-1 cardiomyocytes with ectopic expression of K2P1 channels recapitulate two levels of resting membrane potential. These cardiomyocytes display N-shaped current-voltage relationships that cross the voltage axis three times and the first and third zero-current potentials match the two levels of resting membrane potential. Inhibition of K2P1 expression eliminates the phenomenon, indicating contributions of Kir2.1 and K2P1 channels to two levels of resting membrane potential. Second, in Chinese hamster ovary cells that heterologously express the channels, Kir2.1 currents non-linearly counterbalance hypokalaemia-induced K2P1 leak cation currents, yielding the N-shaped current-voltage relationships, causing the resting membrane potential to spontaneously jump from hyperpolarization at the first zero-current potential to depolarization at the third zero-current potential, again recapitulating two levels of resting membrane potential. These findings reveal ionic mechanisms of the two levels of resting membrane potential, demonstrating a previously unknown mechanism for the regulation of excitability, and support the hypothesis that Kir2 currents non-linearly balance inward background cation currents, accounting for two levels of resting membrane potential of human cardiomyocytes.

Hypokalaemia: Addressing human factors and improving education around prescription and administration of Intravenous(IV) Potassium infusion in Trauma and Orthopaedics

A high incidence of hypokalaemia was noted in Trauma and Orthopaedics of Ninewells Hospital. We sought to establish the reason behind this and implemented three PDSA cycles via questionnaires to 30 ward staff, both doctors and nurses over a 1 week period in December, February and July 2016. Key baseline measures include availability of IV fluids with 40mmol potassium on the wards, confidence prescribing or administering IV fluids with 40mmol potassium, necessity for cardiac monitoring during slow IV potassium replacement and recognition of confusion and learning need in this area. Interventions made include awareness and education session, departmental guideline, improving stock of IV fluids and hypokalaemia management pathway for mild, moderate and severe hypokalaemia. Post-intervention results showed 70% from 33% who said 40mmol IV potassium was available, 87% from 67% were confident prescribing or administering IV potassium and 70% from 27% were aware that cardiac monitoring was not necessary.

Prevalence and prognostic significance of hyperkalemia in hospitalized patients with cirrhosis

BACKGROUND

The prevalence and clinical significance of hyponatremia in cirrhotics have been well studied; however, there are limited data on hyperkalemia in cirrhotics.

AIM

We evaluated the prevalence and prognostic significance of hyperkalemia in hospitalized patients with cirrhosis and developed a prognostic model incorporating potassium for prediction of liver-related death in these patients.

METHODS

The training derivative cohort of patients was used for development of prognostic scores (Group A, n = 1160), which were validated in a large prospective cohort of cirrhotic patients. (Group B, n = 2681) of cirrhosis.

RESULTS

Hyperkalemia was seen in 189 (14.1%) and 336 (12%) in Group A and Group B, respectively. Potassium showed a significant association that was direct with creatinine (P < 0.001) and urea (P < 0.001) and inverse with sodium (P < 0.001). Mortality was also significantly higher in patients with hyperkalemia (P = 0.0015, Hazard Ratio (HR) 1.3, 95% confidence interval 1.11-1.57). Combination of all these parameters into a single value predictor, that is, renal dysfunction index predicted mortality better than the individual components. Combining renal dysfunction index with other known prognostic markers (i.e. serum bilirubin, INR, albumin, hepatic encephalopathy, and ascites) in the "K" model predicted both short-term and long-term mortality with an excellent accuracy (Concordance-index 0.78 and 0.80 in training and validation cohorts, respectively). This was also superior to Model for End-stage Liver Disease, Model for End-stage liver disease sodium (MELDNa), and Child-Turcott-Pugh scores.

CONCLUSIONS

Cirrhotics frequently have impaired potassium homeostasis, which has a prognostic significance. Serum potassium correlates directly with serum creatinine and urea and inversely with serum sodium. The model incorporating serum potassium developed from this study ("K"model) can predict death in advanced cirrhotics with an excellent accuracy.

Effect of the SGLT2 Inhibitor Dapagliflozin on Potassium Levels in Patients with Type 2 Diabetes Mellitus: A Pooled Analysis

INTRODUCTION

Hyperkalemia risk is increased in diabetes, particularly in patients with renal impairment or those receiving angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) or potassium-sparing diuretics. Conversely, other diuretics can increase hypokalemia risk. We assessed the effects of the sodium glucose co-transporter 2 (SGLT2) inhibitor dapagliflozin on serum potassium levels in a pooled analysis of clinical trials in patients with type 2 diabetes mellitus (T2DM).

METHODS

Fourteen randomized, placebo-controlled, double-blind T2DM studies were analyzed: pooled data from 13 studies of ≤24 weeks' duration (dapagliflozin 10 mg, N = 2360; placebo, N = 2295); and one 52-week moderate renal impairment study in patients with baseline eGFR ≥30 to <60 mL/min/1.73 m(2) (dapagliflozin 10 mg, N = 85; placebo, N = 84). Central laboratory serum potassium levels were determined at each study visit.

RESULTS

No clinically relevant mean changes from baseline in serum potassium ≤24 weeks were reported for dapagliflozin 10 mg [-0.05 mmol/L; 95% confidence interval (CI) -0.07, -0.03] versus placebo (-0.02 mmol/L; 95% CI -0.04, 0.00) in the pooled population or in the renal impairment study (-0.03 mmol/L; 95% CI -0.14, 0.08 vs. -0.02 mmol/L; 95% CI -0.13, 0.09, respectively). The incidence rate ratio for serum potassium ≥5.5 mmol/L over 24 weeks for dapagliflozin 10 mg versus placebo was 0.90 (95% CI 0.74, 1.10) in the pooled population; with no increased risk in patients receiving ARBs/ACE inhibitors, or potassium-sparing diuretics, or in those with moderate renal impairment. Slightly more patients receiving dapagliflozin 10 mg had serum potassium ≤3.5 mmol/L versus placebo (5.2% vs. 3.6%); however, no instances of serum potassium ≤2.5 mmol/L were reported.

CONCLUSION

Dapagliflozin is not associated with an increased risk of hyperkalemia or severe hypokalemia in patients with T2DM.

FUNDING

Bristol-Myers Squibb and AstraZeneca.

Ventricular anti-arrhythmic effects of heptanol in hypokalaemic, Langendorff-perfused mouse hearts

Ventricular arrhythmic and electrophysiological properties were examined during normokalaemia (5.2 mM [K⁺]), hypokalaemia (3 mM [K⁺]) or hypokalaemia in the presence of 0.1 or 2 mM heptanol in Langendorff-perfused mouse hearts. Left ventricular epicardial or endocardial monophasic action potential recordings were obtained during right ventricular pacing. Hypokalaemia induced ventricular premature beats (VPBs) in 5 of 7 and ventricular tachycardia (VT) in 6 of 7 hearts (P<0.01), prolonged action potential durations (APD₉₀) from 36.2±1.7 to 55.7±2.0 msec (P<0.01) and shortened ventricular effective refractory periods (VERPs) from 44.5±4.0 to 28.9±3.8 msec (P<0.01) without altering conduction velocities (CVs) (0.17±0.01 m/sec, P>0.05), reducing excitation wavelengths (λ, CV × VERP) from 7.9±1.1 to 5.1±0.3 mm (P<0.05) while increasing critical intervals (CI, APD₉₀-VERP) from −8.3±4.3 to 26.9±2.0 msec (P>0.001). Heptanol (0.1 mM) prevented VT, restored effective refractory period (ERP) to 45.2±2.9 msec without altering CV or APD, returning λ to control values (P>0.05) and CI to 8.4±3.8 msec (P<0.05). Heptanol (2 mM) prevented VPBs and VT, increased ERP to 67.7±7.6 msec (P<0.05), and reduced CV to 0.11±0.1 m/sec (P<0.001) without altering APD (P>0.05), returning λ and CI to control values (P>0.05). Anti-arrhythmic effects of heptanol during hypokalaemia were explicable by ERP changes, scaling λ and CI.

Patiromer: a clinical review

IMPORTANCE

Patiromer FOS (for oral suspension), formerly known as RLY5016, is pending FDA approval for the treatment of hyperkalemia. Once approved, patiromer, as well as a second agent known as sodium zirconium cyclosilicate (ZS-9), will be among the new therapeutic options available to treat hyperkalemia in over 50 years.

OBJECTIVE

The primary objective of this review is to analyze the efficacy and safety of patiromer to treat hyperkalemia and compare its pharmacokinetics to currently available sodium polystyrene sulfonate (SPS) therapy. Patiromer was studied in patients with chronic kidney disease and/or heart failure for both acute and chronic therapy.

EVIDENCE REVIEW

Studies of patiromer were obtained via a literature search of PubMed database and Google Scholar (2000 to the present) using 'patiromer', 'RLY5016', and 'hyperkalemia management' as keywords. Additional references were identified from fda.gov, clinicaltrials.gov, and the pharmaceutical manufacturer, Relypsa Inc.

FINDINGS

Three published clinical trials, ten posters, one clinical trial commentary, three editorials and one oral presentation were obtained. The materials discussed three main clinical trials (PEARL-HF, OPAL-HK and AMETHYST-DN) and examined the safety and efficacy of patiromer in patients with hyperkalemia or at risk for hyperkalemia who have chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), hypertension and/or heart failure (HF) while receiving renin-angiotensin-aldosterone system inhibitors (RAASis). All three studies achieved their primary endpoints and reduced serum potassium. The PEARL-HF study increased the proportion of patients able to titrate their spironolactone dose from 25 mg/day to 50 mg/day in patients with normokalemia who had a history of hyperkalemia or an estimated glomerular filtration rate of <60 mL/min. The OPAL-HK study allowed patients receiving patiromer to remain on their RAASi therapy. The AMETHYST-DN study demonstrated that patiromer reduced and maintained mean serum potassium ≤5.0 mEq/L for up to 1 year, with a low rate of hypokalemia. Adverse events (AEs) were similar between studies. The most commonly reported adverse event was constipation.

CONCLUSIONS AND RELEVANCE

Patiromer is effective in decreasing serum potassium, preventing recurrence of hyperkalemia, and reducing RAASi discontinuation. Compared to current SPS therapy, patiromer may be the preferred option to treat hyperkalemia, once approved. Patiromer is well tolerated and is not associated with serious AEs.

Autophagic degradation of aquaporin-2 is an early event in hypokalemia-induced nephrogenic diabetes insipidus

Hypokalemia (low serum potassium level) is a common electrolyte imbalance that can cause a defect in urinary concentrating ability, i.e., nephrogenic diabetes insipidus (NDI), but the molecular mechanism is unknown. We employed proteomic analysis of inner medullary collecting ducts (IMCD) from rats fed with a potassium-free diet for 1 day. IMCD protein quantification was performed by mass spectrometry using a label-free methodology. A total of 131 proteins, including the water channel AQP2, exhibited significant changes in abundance, most of which were decreased. Bioinformatic analysis revealed that many of the down-regulated proteins were associated with the biological processes of generation of precursor metabolites and energy, actin cytoskeleton organization, and cell-cell adhesion. Targeted LC-MS/MS and immunoblotting studies further confirmed the down regulation of 18 selected proteins. Electron microscopy showed autophagosomes/autophagolysosomes in the IMCD cells of rats deprived of potassium for only 1 day. An increased number of autophagosomes was also confirmed by immunofluorescence, demonstrating co-localization of LC3 and Lamp1 with AQP2 and several other down-regulated proteins in IMCD cells. AQP2 was also detected in autophagosomes in IMCD cells of potassium-deprived rats by immunogold electron microscopy. Thus, enhanced autophagic degradation of proteins, most notably including AQP2, is an early event in hypokalemia-induced NDI.

Evaluation of laboratory critical serum potassium values and their association with clinical symptoms in Chinese Han patients

OBJECTIVES

A retrospective, observational study to evaluate the association between critical potassium values and clinical symptoms, and to define critical potassium limits in hospital inpatients of Chinese Han ethnicity.

METHODS

Adult patients (aged ≥ 18 years) of Chinese Han ethnicity admitted to the Beilun People's Hospital of Ningbo, Zhejiang University, China, were sequentially enrolled. Inpatient data recorded on admission (or at first time during hospital stay for serum potassium values) between 1 January 2011 and 31 December 2012 were used to calculate the percentage of patients with relevant clinical symptoms, the percentage of critical patients (presence of neurological symptoms and deterioration of at least two physiological systems), and the hospital prevalence of clinical symptoms. Correlations between critical serum potassium values and clinical symptoms were determined.

RESULTS

Out of 3 665 included patients, 1 514 patients with a critical serum potassium value (as determined in the present study) were mainly treated in the intensive care unit or the haematology department (low serum potassium, ≤ 2.9 mmol/l), and Renal and Hepatitis departments (high serum potassium, ≥ 6.0 mmol/l). High critical serum potassium values (≥ 6.0 mmol/l) were significantly correlated with clinical symptoms (such as neurological symptoms, loss of appetite, oliguria and hypotension). Low critical serum potassium values (≤ 2.9 mmol/l) were significantly correlated with clinical symptoms (such as neurological symptoms, loss of appetite and dyspnoea).

CONCLUSIONS

Based on the present findings, the lower and upper critical potassium limits were defined as 2.9 mmol/l and 6.0 mmol/l, respectively.

Single-incision laparoscopic adrenalectomy in a patient with acute hypokalemic paralysis due to primary hyperaldosteronism

Acute hypokalemic paralysis is a relatively rare cause of acute weakness. It may resolve spontaneously; however, it may be a potential life-threatening condition. Hypertension may be considered the most important finding in combination with hypokalemic paralysis for raising the suspicion of primary hyperaldosteronism (PHA). A 55-year-old hypertensive Mexican woman was admitted to the Emergency Unit with a sudden onset of generalized paralysis. An endocrinological workup and an abdominal magnetic resonance imaging revealed PHA with a 1.5 cm left adrenal tumor. After preoperative medication, left adrenalectomy was performed with single-incision laparoscopic surgery (SILS). The duration of the surgery was 45 min, and no postoperative complication was encountered. The patient was discharged after 24 h. Hypokalemic paralysis may be due to different conditions, but it may raise the suspicion of PHA in combination with a history of generally mild hypertension. Laparoscopic adrenalectomy is the preferred operation for unilateral adrenal adenomas that cause PHA. Single-incision laparoscopic surgery is a step-forward technique that improves the cosmesis, decreases access-related morbidity, and increases the postoperative recovery. We report a case with acute hypokalemic paralysis due to PHA and treated with SILS.

A survey demonstrating lack of consensus on the sequence of medications for treatment of hyperkalemia among pediatric critical care providers

OBJECTIVE

Hyperkalemia is one of the reversible causes of cardiac arrest in children. The Advanced Cardiovascular Life Support guidelines have specific recommendations on the choice and sequence of medications for treatment of life-threatening hyperkalemia. However, the Pediatric Advanced Life Support guidelines have no specific treatment recommendations. The objective of this study was to measure the extent to which opinions diverge among pediatricians on the choice and sequence of medication administration in the management of hyperkalemia during cardiac arrest.

DESIGN

Scenario-based survey.

SETTING

A hypothetical hospital area covered by the pediatric rapid response team.

PATIENTS

A hypothetical scenario of a 7-year old child receiving a blood transfusion who is suddenly unresponsive and found to be in pulseless ventricular tachycardia with stat labs revealing a potassium level of 8.3.

INTERVENTIONS

A scenario-based survey of PICU fellows and attendings at a PICU Fellows Boot Camp.

MEASUREMENT AND MAIN RESULTS

Eighty-four fellows and 24 attendings responded to the survey. The response rate was 89%. Calcium was chosen most frequently as the first drug to be administered (calcium chloride, 40/115 [34.8%]; calcium gluconate, 62/115 [53.9%]) while 38 of 115 respondents (33%) chose a drug other than calcium. Only 17 of 115 respondents (15%) would use calcium, sodium bicarbonate, insulin, and dextrose in the advanced cardiovascular life support-recommended sequence. PICU attendings were significantly more likely to administer the advanced cardiovascular life support-recommended sequence than fellows (attendings, 8/24 [33%] vs fellows, 9/84 [11%]; p = 0.007).

CONCLUSION

This survey revealed notable variability in the choice and sequence of medications for treatment of life-threatening hyperkalemia with surprisingly few participants in compliance with the advanced cardiovascular life support hyperkalemia guidelines. A standardized approach for pediatric life-threatening hyperkalemia is recommended to improve resuscitation quality.

The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer-assisted potassium control

Introduction

The relationship between potassium regulation and outcome is not known. Our first aim in the present study was to determine the relationship between potassium level and variability in (ICU) stay and outcome. The second aim was to evaluate the impact of a computer-assisted potassium regulation protocol.

Methods

We performed a retrospective before-after study including all patients >15 years of age admitted for more than 24 hours to the ICU of our university teaching hospital between 2002 and 2011. Potassium control was fully integrated with computerized glucose control (glucose and potassium regulation program for intensive care patients (GRIP-II)). The potassium metrics that we determined included mean potassium, potassium variability (defined as the standard deviation of all potassium levels) and percentage of ICU time below and above the reference range (3.5 through 5.0 mmol/L). These metrics were determined for the first ICU day (early phase) and the subsequent ICU days (late phase; that is, day 2 to day 7). We also compared potassium metrics and in-hospital mortality before and after GRIP-II was implemented in 2006.

Results

Of all 22,347 ICU admissions, 10,451 (47%) patients were included. A total of 206,987 potassium measurements were performed in these patients. Glucose was regulated by GRIP-II in 4,664 (45%) patients. The overall in-hospital mortality was 22%. There was a U-shaped relationship between the potassium level and in-hospital mortality (P <0.001). Moreover, potassium variability was independently associated with outcome. After implementation of GRIP-II, in the late phase the time below 3.5 mmol/L decreased from 9.2% to 3.9% and the time above 5.0 mmol/L decreased from 6.1% to 5.2%, and potassium variability decreased from 0.31 to 0.26 mmol/L (all P <0.001). The overall decrease in in-hospital mortality from 23.3% before introduction of GRIP-II to 19.9% afterward (P <0.001) was not related to a specific potassium subgroup.

Conclusions

Hypokalemia, hyperkalemia and potassium variability were independently associated with increased mortality. Computerized potassium control clearly resulted in improved potassium metrics.

Hypokalemia in acute medical patients: risk factors and prognosis

OBJECTIVE

Hypokalemia is one of the most common electrolyte disorders in hospitalized patients. It is associated with a high mortality rate among patients with cardiovascular disease. Whether hypokalemia confers a similar risk in an unselected hospitalized population is not well established.

METHODS

We conducted a prospective cohort study involving all first-time admissions (n = 11,988) to the Acute Medical Department at Odense University Hospital linking potassium level at admission with registry data on patient characteristics, laboratory data, redeemed prescriptions, and time of death for the period from August 2009 to August 2011. We estimated hazard ratios for all-cause mortality within 0 to 7 days and 8 to 30 days after admission, comparing patients with hypokalemia at admission (plasma [K(+)] level <3.4 mmol/L) with patients with eukalemia at admission ([K(+)] level of 3.4-3.8 mmol/L).

RESULTS

Hypokalemia occurred in 16.8% of first-time admissions (n = 2011). It was associated with an adjusted hazard ratio [HR] of 1.34 (95% confidence interval [CI], 0.98-1.85) for 7-day mortality and 1.56 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Among patients with more severe hypokalemia (plasma [K(+)] <2.9 mmol/L), the adjusted HR was 2.17 (95% CI, 1.34-3.49) for 7-day mortality and 1.90 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Prognostic factors for both 7-day and 8- to 30-day mortality among hypokalemic patients were increasing age and Charlson Comorbidity Index, whereas there was no prognostic effect of current diuretic or beta-agonist use.

CONCLUSIONS

In a mixed population of hospitalized medical patients, hypokalemia is common, and plasma [K(+)] <2.9 mmol/L is associated with increased 7-day and 8- to 30-day mortality.

Significance of serum potassium level monitoring during the course of post-operative rehabilitation in patients with hypokalemia

OBJECTIVE

Our objective was to evaluate the significance of pre-hospital and post-operative serum potassium level monitoring and hypokalemia intervention in laparotomy patients with hypokalemia.

METHOD

A total of 118 laparotomy patients with hypokalemia were randomly divided into an intervention group (N = 60) and a control group (N = 58). Blood samples were collected for measurement of potassium levels at various time points (pre-admission, admission, 24 h and 48 h post-operation) for both groups. Hypokalemia interventions were administered to patients in the intervention group in the pre-admission period and the post-operative period. Visceral dynamics were assessed after laparotomy in both groups.

RESULT

Average serum potassium levels at admission, time period of drinking, and time of first bowel sound after laparotomy differed significantly (p < 0.001) between the two groups. Average serum potassium levels, first time of defecation, urination, and ambulation at 24 h and 48 h post-operation differed significantly (p < 0.05) between the two groups.

CONCLUSION

An optimal pathway of serum potassium monitoring not only saves limited ward space but also allows for early correction of hypokalemia in patients undergoing laparotomy.

Altered and dynamic ion selectivity of K+ channels in cell development and excitability

K(+) channels play a key role in regulating cellular excitability. It was thought that the strong K(+) selectivity of these channels was static, only altered by mutations in their selectivity filter, which can cause severe genetic disorders. Recent studies demonstrate that selectivity of K(+) channels can also exhibit dynamic changes. Under acidic conditions or in low extracellular K(+) concentrations, the two-pore domain K(+) channel (K2P) TWIK1 becomes permeable to Na(+), shifting from an inhibitory role to an excitatory role. This phenomenon is responsible for the paradoxical depolarization of human cardiomyocytes in pathological hypokalemia, and therefore may contribute to cardiac arrhythmias. In other cell types, TWIK1 produces depolarizing leak currents under physiological conditions. Dynamic ion selectivity also occurs in other K2P channels. Here we review evidence that dynamic selectivity of K2P channels constitutes a new regulatory mechanism of cellular excitability, whose significance is only now becoming appreciated.

Hyperkalemia in hemodialysis patients

Hyperkalemia contributes significantly to high mortality among ESRD patients. Excess intake and inadequate removal are the most common etiologies in HD patients. Although dialysis is the definitive treatment, classical medical therapy must be employed as a temporizing measure to acutely lower serum potassium. Reducing potassium intake through dietetic/nutritional support is critical to reducing the K+ load in ESRD patients and preventing this condition.

Risk of hyperkalemia in patients with moderate chronic kidney disease initiating angiotensin converting enzyme inhibitors or angiotensin receptor blockers: a randomized study

Background

Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are renoprotective but both may increase serum potassium concentrations in patients with chronic kidney disease (CKD). The proportion of affected patients, the optimum follow-up period and whether there are differences between drugs in the development of this complication remain to be ascertained.

Methods

In a randomized, double-blind, phase IV, controlled, crossover study we recruited 30 patients with stage 3 CKD under restrictive eligibility criteria and strict dietary control. With the exception of withdrawals, each patient was treated with olmesartan and enalapril separately for 3 months each, with a 1-week wash-out period between treatments. Patients were clinically assessed on 10 occasions via measurements of serum and urine samples. We used the Cochran–Mantel–Haenszel statistics for comparison of categorical data between groups. Comparisons were also made using independent two-sample t-tests and Welch’s t-test. Analysis of variance (ANOVA) was performed when necessary. We used either a Mann–Whitney or Kruskal-Wallis test if the distribution was not normal or the variance not homogeneous.

Results

Enalapril and olmesartan increased serum potassium levels similarly (0.3 mmol/L and 0.24 mmol/L respectively). The percentage of patients presenting hyperkalemia higher than 5 mmol/L did not differ between treatments: 37% for olmesartan and 40% for enalapril. The mean e-GFR ranged 46.3 to 48.59 ml/mint/1.73 m² in those treated with olmesartan and 46.8 to 48.3 ml/mint/1.73 m² in those with enalapril and remained unchanged at the end of the study. The decreases in microalbuminuria were also similar (23% in olmesartan and 29% in enalapril patients) in the 4 weeks time point. The percentage of patients presenting hyperkalemia, even after a two month period, did not differ between treatments. There were no appreciable changes in sodium and potassium urinary excretion.

Conclusions

Disturbances in potassium balance upon treatment with either olmesartan or enalapril are frequent and without differences between groups. The follow-up of these patients should include control of potassium levels, at least after the first week and the first and second month after initiating treatment.

Trial registration

The trial EudraCT “2008-002191-98”.

Suicide attempt by intravenous potassium self-poisoning: a case report

Introduction. Overdose of potassium is not as frequently encountered in clinical practice as hyperkalaemia due to acute or chronic renal disease. However, potassium overdoses leading to serious consequences do occur. Case Presentation. A 20-year-old nurse student presented with a cardiac arrest with asystole rhythm. Beside the patient were found four 50-mL syringes and empty vials of potassium chloride (20 mL, 10%). After initial resuscitation with epinephrine, 125 mL of a 4.2% intravenous solution of sodium bicarbonate were injected which resulted in the recovery of an effective cardiac activity. The patient recovered without sequelae. Conclusion. The difficulty in this case was to recognize the potassium poisoning. The advanced resuscitation with the use of a specific treatment helped to resuscitate the patient.

Role of the activation gate in determining the extracellular potassium dependency of block of HERG by trapped drugs

Drug induced long QT syndrome (diLQTS) results primarily from block of the cardiac potassium channel HERG (human-ether-a-go-go related gene). In some cases long QT syndrome can result in the lethal arrhythmia torsade de pointes, an arrhythmia characterized by a rapid heart rate and severely compromised cardiac output. Many patients requiring medication present with serum potassium abnormalities due to a variety of conditions including gastrointestinal dysfunction, renal and endocrine disorders, diuretic use, and aging. Extracellular potassium influences HERG channel inactivation and can alter block of HERG by some drugs. However, block of HERG by a number of drugs is not sensitive to extracellular potassium. In this study, we show that block of WT HERG by bepridil and terfenadine, two drugs previously shown to be trapped inside the HERG channel after the channel closes, is insensitive to extracellular potassium over the range of 0 mM to 20 mM. We also show that bepridil block of the HERG mutant D540K, a mutant channel that is unable to trap drugs, is dependent on extracellular potassium, correlates with the permeant ion, and is independent of HERG inactivation. These results suggest that the lack of extracellular potassium dependency of block of HERG by some drugs may in part be related to the ability of these drugs to be trapped inside the channel after the channel closes.

Severe Hypokalemia Masquerading Myocardial Ischemia

An advanced degree of body potassium deficit may produce striking changes in the electrocardiogram (ECG). These changes can result in incidental findings on the 12-lead ECG or precipitate potentially life-threatening dysrhythmias. Although usually readily recognized, at times these abnormalities may be confused with myocardial ischemia. The object was to report a case of severe hypokalemia mimicking myocardial ischemia. A 33-year-old, previously healthy man, presented to the Emergency Department (ED) with a progressive weakness and chest discomfort. The electrocardiogram showed a marked ST-segment depression in leads II, III, aVF, V₁-V₆. The initial diagnosis was non ST-elevation myocardial infarction. Echocardiography was normal and troponin levels were within normal limits. A more detailed history revealed that the patient had an episode of acute gastroenteritis with diarrhea and vomiting. Serum chemistries were notable for a potassium concentration of 1,8 mmol per liter. With aggressive electrolyte correction, the ECG abnormalities reverted as potassium levels normalized. Hypokalemia induced ST-segment depression may simulate myocardial ischemia. The differential diagnosis might be difficult, especially in the cases when ST changes are accompanied with chest discomfort.

Drug-induced life-threatening potassium disturbances detected by a pharmacovigilance program from laboratory signals

PURPOSE

Detection and reporting of drug-induced life-threatening potassium disturbances and the study of associated factors under a Pharmacovigilance Program using Laboratory Signals at a Hospital (PPLSH) during a 2-year period.

METHODS

All serum potassium levels <2 mmol/l or >7 mmol/l detected at admission to the hospital, including those of patients who died in the emergency ward or during hospitalization, were monitored prospectively from January 2009 through to December 2010. The incidence rate of each etiology of potassium disturbances was calculated. Factors associated with drug-induced potassium disturbances were detected using a multiple logistic regression model.

RESULTS

The incidence of true life-threatening drug-induced hyper- and hypokalemia events was 3 and 4.32 (Poisson 95 % confidence interval 1.62-10.24), respectively, per 10,000 admissions. Of the severe potassium disturbances, 32.3 % were drug-induced, and 23 % were lethal. We identified previously undescribed pharmacological causes of hyperkalemia (risedronate, doxazosin) and hypokalemia (acyclovir, teicoplanin, cefepime, meropenem, dexketoprofen colistimethate). Significant predictor factors associated with drug-induced hyperkalemia were the use of polypharmacy (>5 drugs), age (>74 years), sex (female) and kidney disease (glomerular filtration rate <60 ml/min) with the presence of ≥4 comorbid conditions. The only predictor of drug-induced hypokalemia was the use of >5 drugs. The triggering factor associated with drug-induced hyperkalemia and hypokalemia was azotemia and hypoalbuminemia, respectively.

CONCLUSIONS

Drug-induced life-threatening potassium disturbances remain a relevant problem. Potential strategies for prevention are to avoid polypharmacy, early discontinuation of treatment of drugs causing hyperkalemia or nephrotoxicity in cases of various clinical situations (cardiac descompensation, infection, hypovolemia) or obstructive causes, and insistence on albumin control during hospitalization.

TWIK-1 two-pore domain potassium channels change ion selectivity and conduct inward leak sodium currents in hypokalemia

Background potassium (K+) channels, which are normally selectively permeable to K+, maintain the cardiac resting membrane potential at around -80 mV. In subphysiological extracellular K+ concentrations ([K+]o), which occur in pathological hypokalemia, the resting membrane potential of human cardiomyocytes can depolarize to around -50 mV, whereas rat and mouse cardiomyocytes become hyperpolarized, consistent with the Nernst equation for K+. This paradoxical depolarization of cardiomyocytes in subphysiological [K+]o, which may contribute to cardiac arrhythmias, is thought to involve an inward leak sodium (Na+) current. Here, we show that human cardiac TWIK-1 (also known as K2P1) two-pore domain K+ channels change ion selectivity, becoming permeable to external Na+, and conduct inward leak Na+ currents in subphysiological [K+]o. A specific threonine residue (Thr118) within the pore selectivity sequence TxGYG was required for this altered ion selectivity. Mouse cardiomyocyte-derived HL-1 cells exhibited paradoxical depolarization with ectopic expression of TWIK-1 channels, whereas TWIK-1 knockdown in human spherical primary cardiac myocytes eliminated paradoxical depolarization. These findings indicate that ion selectivity of TWIK-1 K+ channels changes during pathological hypokalemia, elucidate a molecular basis for inward leak Na+ currents that could trigger or contribute to cardiac paradoxical depolarization in lowered [K+]o, and identify a mechanism for regulating cardiac excitability.

Haemodynamic consequences of changing potassium concentrations in haemodialysis fluids

BACKGROUND

A rapid decrease of serum potassium concentrations during haemodialysis produces a significant increase in blood pressure parameters at the end of the session, even if effects on intra-dialysis pressure are not seen. Paradoxically, in animal models potassium is a vasodilator and decreases myocardial contractility. The purpose of this trial is to study the precise haemodynamic consequences induced by acute changes in potassium concentration during haemodialysis.

METHODS

In 24 patients, 288 dialysis sessions, using a randomised single blind crossover design, we compared six dialysate sequences with different potassium profiles. The dialysis sessions were divided into 3 tertiles, casually modulating potassium concentration in the dialysate between the value normally used K and the two cut-off points K+1 and K-1 mmol/l. Haemodynamics were evaluated in a non-invasive manner using a finger beat-to-beat monitor.

RESULTS

Comparing K-1 and K+1, differences were found within the tertiles regarding systolic (+5.3, +6.6, +2.3 mmHg, p < 0.05, < 0.05, ns) and mean blood pressure (+4.3, +6.4, -0.5 mmHg, p < 0.01, < 0.01, ns), as well as peripheral resistance (+212, +253, -4 dyne.sec.cm-5, p < 0.05, < 0.05, ns). The stroke volume showed a non-statistically-significant inverse trend (-3.1, -5.2, -0.2 ml). 18 hypotension episodes were recorded during the course of the study. 72% with K-1, 11% with K and 17% with K+1 (p < 0.01 for comparison K-1 vs. K and K-1 vs. K+1).

CONCLUSIONS

A rapid decrease in the concentration of serum potassium during the initial stage of the dialysis-obtained by reducing the concentration of potassium in the dialysate-translated into a decrease of systolic and mean blood pressure mediated by a decrease in peripheral resistance. The risk of intra-dialysis hypotension inversely correlates to the potassium concentration in the dialysate.

TRIAL REGISTRATION NUMBER

NCT01224314.