Transfusion-associated hyperkalemia in pediatric population: Prevalence, risk factors, survival, infusion rate, and RBC unit features

BACKGROUND

Hyperkalemia is a rare life-threatening complication of red blood cell (RBC) transfusion. Stored RBCs leak intracellular potassium (K+) into the supernatant; irradiation potentiates the K+ leak. As the characteristics of patients and implicated RBCs have not been studied systematically, a multicenter study of transfusion-associated hyperkalemia (TAH) in the pediatric population was conducted through the AABB Pediatric Transfusion Medicine Subsection.

STUDY DESIGN

The medical records of patients <18 years old were retrospectively queried for hyperkalemia occurrence during or ≤12 h after the completion of RBC transfusion in a 1-year period. Collected data included patient demographics, diagnosis, medical history, timing of hyperkalemia and transfusion, mortality, and RBC unit characteristics.

RESULTS/FINDINGS

A total of 3777 patients received 19,649 RBC units during the study period in four facilities. TAH was found in 35 patients (0.93%) in 37 occurrences. The patient median age and weight were 1.28 years and 9.80 kg, respectively. All patients had multiple serious comorbidities. There were 79 RBC units transfused in the TAH events; 62% were irradiated, and the median age of the units was 10 days. The median total RBC volume transfused ≤12 h before TAH was 24% of patient estimated total blood volume, and the median infusion rate (IR) was19.6 ml/kg/h. Mortality rate within 1 day after the TAH event was 20%.

CONCLUSIONS

The prevalence of TAH in children was low; however, the 1-day mortality rate was 20%. Patients with multiple comorbidities may be at higher risk for TAH. The IR was higher for patients who had TAH than the IR threshold for safe transfusion.

Potassium binders for chronic hyperkalaemia in people with chronic kidney disease

BACKGROUND

Hyperkalaemia is a common electrolyte abnormality caused by reduced renal potassium excretion in patients with chronic kidney diseases (CKD). Potassium binders, such as sodium polystyrene sulfonate and calcium polystyrene sulfonate, are widely used but may lead to constipation and other adverse gastrointestinal (GI) symptoms, reducing their tolerability. Patiromer and sodium zirconium cyclosilicate are newer ion exchange resins for treatment of hyperkalaemia which may cause fewer GI side-effects. Although more recent studies are focusing on clinically-relevant endpoints such as cardiac complications or death, the evidence on safety is still limited. Given the recent expansion in the available treatment options, it is appropriate to review the evidence of effectiveness and tolerability of all potassium exchange resins among people with CKD, with the aim to provide guidance to consumers, practitioners, and policy-makers.

OBJECTIVES

To assess the benefits and harms of potassium binders for treating chronic hyperkalaemia among adults and children with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 10 March 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-randomised controlled studies (quasi-RCTs) evaluating potassium binders for chronic hyperkalaemia administered in adults and children with CKD.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risks of bias and extracted data. Treatment estimates were summarised by random effects meta-analysis and expressed as relative risk (RR) or mean difference (MD), with 95% confidence interval (CI). Evidence certainty was assessed using GRADE processes.

MAIN RESULTS

Fifteen studies, randomising 1849 adult participants were eligible for inclusion. Twelve studies involved participants with CKD (stages 1 to 5) not requiring dialysis and three studies were among participants treated with haemodialysis. Potassium binders included calcium polystyrene sulfonate, sodium polystyrene sulfonate, patiromer, and sodium zirconium cyclosilicate. A range of routes, doses, and timing of drug administration were used. Study duration varied from 12 hours to 52 weeks (median 4 weeks). Three were cross-over studies. The mean study age ranged from 53.1 years to 73 years. No studies evaluated treatment in children. Some studies had methodological domains that were at high or unclear risks of bias, leading to low certainty in the results. Studies were not designed to measure treatment effects on cardiac arrhythmias or major GI symptoms. Ten studies (1367 randomised participants) compared a potassium binder to placebo. The certainty of the evidence was low for all outcomes. We categorised treatments in newer agents (patiromer or sodium zirconium cyclosilicate) and older agents (calcium polystyrene sulfonate and sodium polystyrene sulfonate). Patiromer or sodium zirconium cyclosilicate may make little or no difference to death (any cause) (4 studies, 688 participants: RR 0.69, 95% CI 0.11, 4.32; I2 = 0%; low certainty evidence) in CKD. The treatment effect of older potassium binders on death (any cause) was unknown. One cardiovascular death was reported with potassium binder in one study, showing that there was no difference between patiromer or sodium zirconium cyclosilicate and placebo for cardiovascular death in CKD and HD. There was no evidence of a difference between patiromer or sodium zirconium cyclosilicate and placebo for health-related quality of life (HRQoL) at the end of treatment (one study) in CKD or HD. Potassium binders had uncertain effects on nausea (3 studies, 229 participants: RR 2.10, 95% CI 0.65, 6.78; I2 = 0%; low certainty evidence), diarrhoea (5 studies, 720 participants: RR 0.84, 95% CI 0.47, 1.48; I2 = 0%; low certainty evidence), and vomiting (2 studies, 122 participants: RR 1.72, 95% CI 0.35 to 8.51; I2 = 0%; low certainty evidence) in CKD. Potassium binders may lower serum potassium levels (at the end of treatment) (3 studies, 277 participants: MD -0.62 mEq/L, 95% CI -0.97, -0.27; I2 = 92%; low certainty evidence) in CKD and HD. Potassium binders had uncertain effects on constipation (4 studies, 425 participants: RR 1.58, 95% CI 0.71, 3.52; I2 = 0%; low certainty evidence) in CKD. Potassium binders may decrease systolic blood pressure (BP) (2 studies, 369 participants: MD -3.73 mmHg, 95%CI -6.64 to -0.83; I2 = 79%; low certainty evidence) and diastolic BP (one study) at the end of the treatment. No study reported outcome data for cardiac arrhythmias or major GI events. Calcium polystyrene sulfonate may make little or no difference to serum potassium levels at end of treatment, compared to sodium polystyrene sulfonate (2 studies, 117 participants: MD 0.38 mEq/L, 95% CI -0.03 to 0.79; I2 = 42%, low certainty evidence). There was no evidence of a difference in systolic BP (one study), diastolic BP (one study), or constipation (one study) between calcium polystyrene sulfonate and sodium polystyrene sulfonate. There was no difference between high-dose and low-dose patiromer for death (sudden death) (one study), stroke (one study), myocardial infarction (one study), or constipation (one study). The comparative effects whether potassium binders were administered with or without food, laxatives, or sorbitol, were very uncertain with insufficient data to perform meta-analysis.

AUTHORS' CONCLUSIONS

Evidence supporting clinical decision-making for different potassium binders to treat chronic hyperkalaemia in adults with CKD is of low certainty; no studies were identified in children. Available studies have not been designed to measure treatment effects on clinical outcomes such as cardiac arrhythmias or major GI symptoms. This review suggests the need for a large, adequately powered study of potassium binders versus placebo that assesses clinical outcomes of relevance to patients, clinicians and policy-makers. This data could be used to assess cost-effectiveness, given the lack of definitive studies and the clinical importance of potassium binders for chronic hyperkalaemia in people with CKD.

Racial and Ethnic Differences in Mortality Associated with Serum Potassium in Incident Peritoneal Dialysis Patients

BACKGROUND

Abnormalities in serum potassium are risk factors for sudden cardiac death and arrhythmias among dialysis patients. Although a previous study in hemodialysis patients has shown that race/ethnicity may impact the relationship between serum potassium and mortality, the relationship remains unclear among peritoneal dialysis (PD) patients where the dynamics of serum potassium is more stable.

METHODS

Among 17,664 patients who started PD between January 1, 2007 and December 31, 2011 in a large US dialysis organization, we evaluated the association of serum potassium levels with all-cause and arrhythmia-related deaths across race/ethnicity using time-dependent Cox models with adjustments for demographics. We also used restricted cubic spline functions for serum potassium levels to explore non-linear associations.

RESULTS

Baseline serum potassium levels were the highest among Hispanics (4.2 ± 0.7 mEq/L) and lowest among non-Hispanic blacks (4.0 ± 0.7 mEq/L). Among 2,949 deaths during the follow-up of median 2.2 (interquartile ranges 1.3-3.2) years, 683 (23%) were arrhythmia-related deaths. Overall, both hyperkalemia and hypokalemia (i.e., serum potassium levels >5.0 and <3.5 mEq/L, respectively) were associated with higher all-cause and arrhythmia-related mortality. In a stratified analysis according to race/ethnicity, the association of hypokalemia with all-cause and arrhythmia-related mortality was consistent with an attenuation for arrhythmia-related mortality in non-Hispanic blacks. Hyperkalemia was associated with all-cause and arrhythmia-related mortality in non-Hispanic whites and non-Hispanic blacks, but no association was observed in Hispanics.

CONCLUSION

Among incident PD patients, hypokalemia was consistently associated with all-cause and arrhythmia-related deaths irrespective of race/ethnicity. However, while hyperkalemia was associated with both death outcomes in non-Hispanic blacks and whites, it was not associated with either death outcome in Hispanic patients. Further studies are needed to demonstrate whether different strategies should be followed for the management of serum potassium levels according to race/ethnicity.

Development of a health economic model to evaluate the potential benefits of optimal serum potassium management in patients with heart failure

AIMS

Patients with heart failure are at increased risk of hyperkalemia, particularly when treated with renin-angiotensin-aldosterone system inhibitor (RAASi) agents. This study developed a model to quantify the potential health and economic value associated with sustained potassium management and optimal RAASi therapy in heart failure patients.

MATERIALS AND METHODS

A patient-level, fixed-time increment stochastic simulation model was designed to characterize the progression of heart failure through New York Heart Association functional classes, and predict associations between serum potassium levels, RAASi use, and consequent long-term outcomes. Following internal and external validation exercises, model analyses sought to quantify the health and economic benefits of optimizing both serum potassium levels and RAASi therapy in heart failure patients. Analyses were conducted using a UK payer perspective, independent of costs and utilities related to pharmacological potassium management.

RESULTS

Validation against multiple datasets demonstrated the predictive capability of the model. Compared to those who discontinued RAASi to manage serum potassium, patients with normokalemia and ongoing RAASi therapy benefited from longer life expectancy (+1.38 years), per-patient quality-adjusted life year gains (+0.53 QALYs), cost savings (£110), and associated net monetary benefit (£10,679 at £20,000 per QALY gained) over a lifetime horizon. The predicted value of sustained potassium management and ongoing RAASi treatment was largely driven by reduced mortality and hospitalization risks associated with optimal RAASi therapy.

LIMITATIONS

Several modeling assumptions were made to account for a current paucity of published literature; however, ongoing refinement and validation of the model will ensure its continued accuracy as the clinical landscape of hyperkalemia evolves.

CONCLUSIONS

Predictions generated by this novel modeling approach highlight the value of sustained potassium management to avoid hyperkalemia, enable RAASi therapy, and improve long-term health economic outcomes in patients with heart failure.

Association of Serum Potassium with All-Cause Mortality in Patients with and without Heart Failure, Chronic Kidney Disease, and/or Diabetes

BACKGROUND

The relationship between serum potassium, mortality, and conditions commonly associated with dyskalemias, such as heart failure (HF), chronic kidney disease (CKD), and/or diabetes mellitus (DM) is largely unknown.

METHODS

We reviewed electronic medical record data from a geographically diverse population (n = 911,698) receiving medical care, determined the distribution of serum potassium, and the relationship between an index potassium value and mortality over an 18-month period in those with and without HF, CKD, and/or DM. We examined the association between all-cause mortality and potassium using a cubic spline regression analysis in the total population, a control group, and in HF, CKD, DM, and a combined cohort.

RESULTS

27.6% had a potassium <4.0 mEq/L, and 5.7% had a value ≥5.0 mEq/L. A U-shaped association was noted between serum potassium and mortality in all groups, with lowest all-cause mortality in controls with potassium values between 4.0 and <5.0 mEq/L. All-cause mortality rates per index potassium between 2.5 and 8.0 mEq/L were consistently greater with HF 22%, CKD 16.6%, and DM 6.6% vs. controls 1.2%, and highest in the combined cohort 29.7%. Higher mortality rates were noted in those aged ≥65 vs. 50-64 years. In an adjusted model, all-cause mortality was significantly elevated for every 0.1 mEq/L change in potassium <4.0 mEq/L and ≥5.0 mEq/L. Diuretics and renin-angiotensin-aldosterone system inhibitors were related to hypokalemia and hyperkalemia respectively.

CONCLUSION

Mortality risk progressively increased with dyskalemia and was differentially greater in those with HF, CKD, or DM.

Hyperkalemia is Associated with Increased 30-Day Mortality in Hip Fracture Patients

Abnormal plasma concentrations of potassium in the form of hyper- and hypokalemia are frequent among hospitalized patients and have been linked to poor outcomes. In this study, we examined the prevalence of hypo- and hyperkalemia in patients admitted with a fractured hip as well as the association with 30-day mortality in these patients. A total of 7293 hip fracture patients (aged 60 years or above) with admission plasma potassium measurements were included. Data on comorbidity, medication, and death was retrieved from national registries. The association between plasma potassium and mortality was examined using Cox proportional hazards models adjusted for age, sex, and comorbidities. The prevalence of hypo- and hyperkalemia on admission was 19.8% and 6.6%, respectively. The 30-day mortality rates were increased for patients with hyperkalemia (21.0%, p < 0.0001) compared to normokalemic patients (9.5%), whereas hypokalemia was not significantly associated with mortality. After adjustment for age, sex, and individual comorbidities, hyperkalemia was still associated with increased risk of death 30 days after admission (HR = 1.93 [1.55-2.40], p < 0.0001). After the same adjustments, hypokalemia remained non-associated with increased risk of 30-day mortality (HR = 1.06 [0.87-1.29], p = 0.6). Hyperkalemia, but not hypokalemia, at admission is associated with increased 30-day mortality after a hip fracture.

The Relation of Serum Potassium Concentration with Cardiovascular Events and Mortality in Community-Living Individuals

BACKGROUND AND OBJECTIVES

Hyperkalemia is associated with adverse outcomes in patients with CKD and in hospitalized patients with acute medical conditions. Little is known regarding hyperkalemia, cardiovascular disease (CVD), and mortality in community-living populations. In a pooled analysis of two large observational cohorts, we investigated associations between serum potassium concentrations and CVD events and mortality, and whether potassium-altering medications and eGFR<60 ml/min per 1.73 m2 modified these associations.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 9651 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Cardiovascular Health Study (CHS), who were free of CVD at baseline (2000-2002 in the MESA and 1989-1993 in the CHS), we investigated associations between serum potassium categories (<3.5, 3.5-3.9, 4.0-4.4, 4.5-4.9, and ≥5.0 mEq/L) and CVD events, mortality, and mortality subtypes (CVD versus non-CVD) using Cox proportional hazards models, adjusting for demographics, time-varying eGFR, traditional CVD risk factors, and use of potassium-altering medications.

RESULTS

Compared with serum potassium concentrations between 4.0 and 4.4 mEq/L, those with concentrations ≥5.0 mEq/L were at higher risk for all-cause mortality (hazard ratio, 1.41; 95% confidence interval, 1.12 to 1.76), CVD death (hazard ratio, 1.50; 95% confidence interval, 1.00 to 2.26), and non-CVD death (hazard ratio, 1.40; 95% confidence interval, 1.07 to 1.83) in fully adjusted models. Associations of serum potassium with these end points differed among diuretic users (Pinteraction<0.02 for all), such that participants who had serum potassium ≥5.0 mEq/L and were concurrently using diuretics were at higher risk of each end point compared with those not using diuretics.

CONCLUSIONS

Serum potassium concentration ≥5.0 mEq/L was associated with all-cause mortality, CVD death, and non-CVD death in community-living individuals; associations were stronger in diuretic users. Whether maintenance of potassium within the normal range may improve clinical outcomes requires future study.

[Not Available]

Zusammenfassung. Die Hyperkaliämie bei Dialysepatienten ist die häufigste Elektrolytstörung, die mit erhöhtem Risiko für Herz-Kreislauf-Mortalität und arrhythmogenen Tod verbunden ist. Die Prävalenz der Hyperkaliämie bei Dialysepatienten liegt bei ca. 8,7–10 %, die Sterblichkeit im Zusammenhang mit Hyperkaliämie bei ca. 3,1/1000 Patienten-Jahre, und etwa 24 % der Patienten mit terminaler Niereninsuffizienz werden aufgrund einer schweren Hyperkaliämie notfallmässig dialysiert. Um die Zeit bis Hämodialyse-Beginn zu überbrücken, ist es sinnvoll, die Therapie-Strategien zu kombinieren. Die Hyperkaliämie bei Hämodialysepatienten ist oft durch Diätfehler verursacht. Nach Korrektur der Hyperkaliämie muss deren Ursache geklärt werden.

Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort

BACKGROUND

Hyperkalemia is observed in chronic kidney disease patients and may be a risk factor for life-threatening arrhythmias and death. Race/ethnicity may be important modifiers of the potassium-mortality relationship in maintenance hemodialysis (MHD) patients given that potassium intake and excretion vary among minorities.

METHODS

We examined racial/ethnic differences in baseline serum potassium levels and all-cause and cardiovascular mortality using Cox proportional hazard models and restricted cubic splines in a cohort of 102,241 incident MHD patients. Serum potassium was categorized into 6 groups: ≤3.6, >3.6 to ≤4.0, >4.0 to ≤4.5 (reference), >4.5 to ≤5.0, >5.0 to ≤5.5, and >5.5 mEq/L. Models were adjusted for case-mix and malnutrition-inflammation cachexia syndrome (MICS) covariates.

RESULTS

The cohort was composed of 50% whites, 34% African-Americans, and 16% Hispanics. Hispanics tended to have the highest baseline serum potassium levels (mean ± SD: 4.58 ± 0.55 mEq/L). Patients in our cohort were followed for a median of 1.3 years (interquartile range 0.6-2.5). In our cohort, associations between higher potassium (>5.5 mEq/L) and higher mortality risk were observed in African-American and whites, but not Hispanic patients in models adjusted for case-mix and MICS covariates. While in Hispanics only, lower serum potassium (<3.6 mEq/L) levels were associated with higher mortality risk. Similar trends were observed for cardiovascular mortality.

CONCLUSIONS

Higher potassium levels were associated with higher mortality risk in white and African-American MHD patients, whereas lower potassium levels were associated with higher death risk in Hispanics. Further studies are needed to determine the underlying mechanisms for the differential association between potassium and mortality across race/ethnicity.

Serum Potassium, Mortality, and Kidney Outcomes in the Atherosclerosis Risk in Communities Study

OBJECTIVES

To investigate the association between serum potassium, mortality, and kidney outcomes in the general population and whether potassium-altering medications modify these associations.

PATIENTS AND METHODS

We studied 15,539 adults in the Atherosclerosis Risk in Communities Study. Cox proportional hazard regression was used to investigate the association of serum potassium at baseline (1987-1989), evaluated categorically (hypokalemia, <3.5 mmol/L; normokalemia, ≥3.5 and <5.5 mmol/L; hyperkalemia, ≥5.5 mmol/L) and continuously using linear spline terms (knots at 3.5 and 5.5 mmol/L), with mortality, sudden cardiac death, incident chronic kidney disease, and end-stage renal disease. The end date of follow-up for all outcomes was December 31, 2012. We also evaluated whether classes of potassium-altering medications modified the association between serum potassium and adverse outcomes.

RESULTS

Overall, 413 (2.7%) of the participants had hypokalemia and 321 (2.1%) had hyperkalemia. In a fully adjusted model, hyperkalemia was significantly associated with mortality (hazard ratio, 1.24; 95% CI, 1.04-1.49) but not sudden cardiac death, chronic kidney disease, or end-stage renal disease. Hypokalemia as a categorical variable was not associated with any outcome; however, associations of hypokalemia with all-cause mortality and kidney outcomes were observed among those who were not taking potassium-wasting diuretics (all P for interaction, <.001).

CONCLUSIONS

Higher values of serum potassium were associated with a higher risk of mortality in the general population. Lower levels of potassium were associated with adverse kidney outcomes and mortality among participants not taking potassium-wasting diuretics.

Serum Potassium Levels and Mortality in Hemodialysis Patients: A Retrospective Cohort Study

BACKGROUND

Hyperkalemia is common in patients receiving maintenance hemodialysis. However, few studies have examined the association between serum potassium level and mortality.

METHODS

This study used annual cohorts of hemodialysis patients during 2007-2010. To determine hyperkalemia prevalence, monthly hyperkalemia was defined as serum potassium level ≥5.5 mEq/l; prevalence was calculated as a ratio of hyperkalemia episodes to follow-up time, reported separately by long and short interdialytic interval. To determine the impact of hyperkalemia on mortality, patients in the 2010 cohort were followed from first potassium measurement until death or a censoring event; hyperkalemia was defined, sequentially, by potassium levels 5.5-6.0 mEq/l at 0.1 mEq/l intervals. Time-dependent Cox proportional hazards modeling was used to estimate the association between hyperkalemia and mortality.

RESULTS

The 4 annual cohorts ranged from 28,774 to 36,888 patients. Mean age was approximately 63 years, about 56% were men, 51% were white and 44% had end-stage renal disease caused by diabetes. Hyperkalemia prevalence was consistently estimated at 16.3-16.8 events per 100 patient-months. Prevalence on the day after the long interdialytic interval was 2.0-2.4 times as high as on the day after the short interval. Hyperkalemia, when defined as serum potassium ≥5.7 mEq/l, was associated with all-cause mortality (adjusted hazards ratio (AHR) 1.13, 95% CI 1.01-1.28, p = 0.037, vs. <5.7 mEq/l) after adjustment. AHRs increased progressively as the hyperkalemia threshold increased, reaching 1.37 (95% CI 1.16-1.62, p < 0.0001) for ≥6.0 mEq/l.

CONCLUSIONS

The long interdialytic interval was associated with increased likelihood of hyperkalemia. Hyperkalemia was associated with all-cause mortality beginning at serum potassium ≥5.7 mEq/l; mortality risk estimates increased ordinally through ≥6.0 mEq/l, suggesting a threshold at which serum potassium becomes substantially more dangerous.

Prevalence and Prognosis of Hyperkalemia in Patients with Acute Myocardial Infarction

BACKGROUND

Hyperkalemia is common and potentially dangerous in hospitalized patients; its contemporary prevalence and prognostic importance after acute myocardial infarction are not well described.

METHODS

In 38,689 consecutive patients with acute myocardial infarction from the Cerner Health Facts database, we evaluated the association between maximum in-hospital potassium levels and in-hospital mortality. Patients were stratified by dialysis status and grouped by maximum potassium as follows: <5 mEq/L, 5 to <5.5 mEq/L, 5.5 to <6.0 mEq/L, 6.0 to <6.5 mEq/L, and ≥6.5 mEq/L. Multivariable logistic regression was used to adjust for multiple patient and site characteristics. The relationship between the number of hyperkalemic values and the in-hospital mortality was evaluated.

RESULTS

Of 38,689 patients with acute myocardial infarction, 886 were on dialysis. The rate of hyperkalemia (maximum potassium ≥5.0 mEq/L) was 22.6% in patients on dialysis and 66.8% in patients not on dialysis. Moderate to severe hyperkalemia (maximum potassium ≥5.5 mEq/L) occurred in 9.8% of patients. There was a steep increase in mortality with higher maximum potassium levels. In-hospital mortality exceeded 15% once maximum potassium was ≥5.5 mEq/L regardless of dialysis status. The relationship between higher maximum potassium and increased mortality risk persisted after multivariable adjustment. In addition, patients with a greater number of hyperkalemic values (vs a single value) experienced higher in-hospital mortality.

CONCLUSIONS

Hyperkalemia is common in patients who are hospitalized with acute myocardial infarction. Higher maximum potassium levels and number of hyperkalemic events are associated with a steep mortality increase, with higher risks for adverse outcomes observed even at mild levels of hyperkalemia. Whether more intensive management of hyperkalemia may improve outcomes in patients with acute myocardial infarction merits further study.

The burden of hyperkalemia in patients with cardiovascular and renal disease

Hyperkalemia is a potentially serious condition that can result in life-threatening cardiac arrhythmias and is associated with an increased mortality risk. Patients older than 65 years who have an advanced stage of chronic kidney disease (stage 3 or higher), diabetes, and/or chronic heart failure are at higher risk for hyperkalemia. To reduce disease progression and improve outcomes in these groups of patients, modulation of the renin-angiotensin-aldosterone system (RAAS) is recommended by guidelines. One limiting factor of RAAS inhibitors at proven doses is the increased risk for hyperkalemia associated with their use. Although there are effective therapeutic options for the short-term, acute management of hyperkalemia, the available strategies for chronic control of high potassium levels have limited effectiveness. The management of high potassium in the long term often requires withdrawing or reducing the doses of drugs proven to reduce cardiovascular and renal outcomes (eg, RAAS inhibitors) or implementing excessive and often intolerable dietary restrictions. Furthermore, withholding RAAS inhibitors may lead to incremental healthcare costs associated with poor outcomes, such as end-stage renal disease, hospitalizations due to cardiovascular causes, and cardiovascular mortality. As such, there is an important unmet need for novel therapeutic options for the chronic management of patients at risk for hyperkalemia. Potential therapies in development may change the treatment landscape in the near future.

Co-trimoxazole and sudden death in patients receiving inhibitors of renin-angiotensin system: population based study

OBJECTIVE

To determine whether the prescription of co-trimoxazole with an angiotensin converting enzyme inhibitor or angiotensin receptor blocker is associated with sudden death.

DESIGN

Population based nested case-control study.

SETTING

Ontario, Canada, from 1 April 1994 to 1 January 2012.

PARTICIPANTS

Ontario residents aged 66 years or older treated with an angiotensin converting enzyme inhibitor or angiotensin receptor blocker. Cases were those who died suddenly shortly after receiving an outpatient prescription for one of co-trimoxazole, amoxicillin, ciprofloxacin, norfloxacin, or nitrofurantoin. Each case was matched with up to four controls on age, sex, chronic kidney disease, and diabetes.

MAIN OUTCOME MEASURE

Odds ratio for the association between sudden death and exposure to each antibiotic relative to amoxicillin, after adjustment for predictors of sudden death according to a disease risk index.

RESULTS

Of 39,879 sudden deaths, 1027 occurred within seven days of exposure to an antibiotic and were matched to 3733 controls. Relative to amoxicillin, co-trimoxazole was associated with an increased risk of sudden death (adjusted odds ratio 1.38, 95% confidence interval 1.09 to 1.76). The risk was marginally higher at 14 days (adjusted odds ratio 1.54, 1.29 to 1.84). This corresponds to approximately three sudden deaths within 14 days per 1000 co-trimoxazole prescriptions. Ciprofloxacin (a known cause of QT interval prolongation) was also associated with an increased risk of sudden death (adjusted odds ratio 1.29, 1.03 to 1.62), but no such risk was observed with nitrofurantoin or norfloxacin.

CONCLUSIONS

In older patients receiving angiotensin converting enzyme inhibitors or angiotensin receptor blockers, co-trimoxazole is associated with an increased risk of sudden death. Unrecognized severe hyperkalemia may underlie this finding. When appropriate, alternative antibiotics should be considered in such patients.

Acute and chronic cardiovascular effects of hyperkalemia: new insights into prevention and clinical management

The plasma pool of potassium is a partial reflection of the overall body, transient cellular shifts, and potassium elimination regulated by the kidneys. Potassium concentrations elevating above the upper limit of normal (> 5.0 mEq/L) have become more common in cardiovascular practice due to the growing population of patients with chronic kidney disease and the broad applications of drugs that modulate potassium excretion by either reducing production of angiotensin II (angiotensin-converting enzyme inhibitors, direct renin inhibitors, beta-adrenergic receptor antagonists), blocking angiotensin II receptors (angiotensin receptor blockers), or antagonizing the action of aldosterone on mineralocorticoid receptors (mineralocorticoid receptor antagonists). In addition, acute kidney injury, critical illness, crush injuries, and massive red blood cell transfusions can result in hyperkalemia. Progressively more severe elevations in potassium are responsible for abnormalities in cardiac depolarization and repolarization and contractility. Untreated severe hyperkalemia results in sudden cardiac death. Traditional management steps have included reducing dietary potassium and discontinuing potassium supplements; withdrawal of exacerbating drugs; acute treatment with intravenous calcium gluconate, insulin, and glucose; nebulized albuterol; correction of acidosis with sodium bicarbonate for short-term shifts out of the plasma pool; and, finally, gastrointestinal ion exchange with oral sodium polystyrene sulfonate in sorbitol, which is mainly used in the hospital and is poorly tolerated due to gastrointestinal adverse effects. This review explores hyperkalemia as a complication in cardiovascular patients and highlights new acute, chronic, and preventative oral therapies (patiromer calcium, cross-linked polyelectrolyte, ZS-9) that could potentially create a greater margin of safety for vulnerable patients with combined heart and kidney disease.

Penultimate pulse wave velocity, better than baseline pulse wave velocity, predicted mortality in Italian ESRD cohort study - a case for daily hemodialysis for ESRD patients with accelerated pulse wave velocity changes

BACKGROUND

Cardiac disease remains the major cause of death among ESRD patients. Indeed, the risk of cardiovascular events in ESRD is reported to be at least 3.4 fold higher than that of the general population. Moreover, annual mortality rates among ESRD patients on hemodialysis approximate 20%, with cardiovascular disease accounting for almost half of this mortality profile. Despite this knowledge, so far we have been unable to identify treatable pathogenetic factors among ESRD patients to help reverse these poor cardiovascular outcomes. The difficulty to prognosticate cardiovascular mortality in ESRD remains elusive. However, in 2011, our group, for the first time, had demonstrated that cyclic variations of arterial stiffness as measured by pulse wave velocity (PWV) before and after hemodialysis determined mortality differences within an ESRD cohort. We have therefore examined the impact of individual patient-level translational PWV changes over time on mortality outcomes in an Italian ESRD cohort.

STUDY DESIGN AND SETTING

Prospective observational study, 2007-2010, in an Italian ESRD cohort who underwent in-center outpatient conventional thrice weekly hemodialysis.

METHODS

PWV was measured by the foot-to-foot method and repeated after six months. Coronary artery calcification (CAC) was measured at 0, 12 and 24 months. Routine clinical data and patient demographics were recorded and mortality outcomes were analyzed.

RESULTS

Between 2007 and 2010, 466 Italian ESRD patients, 229 males and 237 females, age 19-97 (65.6) years, were followed up for 28.9 months. 128 patients (74M:54F) died. The major causes of death were acute myocardial infarction (AMI) in 47 (37%) patients (age 70, 26M:21F) and sudden death (SD) in 29 (23%) patients (age 72, 19M:10F). Paired PWV data was available in 308 surviving patients and in 106 patients who died. Baseline PWV was lower in surviving vs dead patients 8.46 +/- 1.8 vs 9.43 +/- 3.75 (p=0.0005). Repeat PWV values were unchanged in the 308 survivors (8.46 +/- 1.8 vs 8.53 +/- 1.85, p=0.5, NS). Repeat PWV values increased in the 106 patients who died from 9.43 +/- 3.75 to 12.11 +/- 4.18 (p<0.0001). Of the 29 patients who died from SD, death occurred <12 hours after the last dialysis (ATLD) in 7, >24 hours ATLD in 20 and >48 hours ATLD in 17. Of the 47 patients who died from AMI, 6 died <12 hours ATLD, 35 died >24 hours ATLD and 23 died >48 hours ATLD. Of the 14 ESRD patients in the cohort that died from hyperkalemia, 3 died <12 hours ATLD, 11 died >24 hours ATLD, and 7 died >48 hours ATLD. CAC data scatter did not allow for adequate statistical subgroup analysis but overall, baseline CAC values were higher in the AMI/SD dead patients vs surviving patients.

CONCLUSIONS

This is the first report to show a scalable and direct relationship between translational follow up PWV changes after six months versus observed cardiovascular mortality in an ESRD cohort. We have shown, for the first time, that penultimate PWV, better than baseline PWV, predicted cardiovascular mortality in this ESRD cohort. Moreover, higher proportions of the ESRD deaths from AMI, SD and hyperkalemia occurred during the long inter-dialytic (weekend) period when ESRD patients went for 3 days without hemodialysis. We propose that PWV be monitored among all new ESRD patients, and be repeated after six months of initiation of chronic hemodialysis. Our group had earlier demonstrated in 2012 that daily dialysis reduced PWV in chronic hemodialysis patients. From these study findings, we have proposed that ESRD patients who exhibit elevated initial PWV values, or more so, ESRD patients who demonstrate accelerated PWV values after six months on maintenance chronic hemodialysis should be converted to daily hemodialysis protocol. Furthermore, such patients may require more intense cardiovascular analysis by cardiologists. Further research into new preventative or therapeutic options in this area of ESRD care is warranted.

Mortal hyperkalemia disturbances in rats are NO-system related. The life saving effect of pentadecapeptide BPC 157

We demonstrate the full counteracting ability of stable gastric pentadecapeptide BPC 157 against KCl-overdose (intraperitoneal (i), intragastric (ii), in vitro (iii)), NO-system related. (i) We demonstrated potential (/kg) of: BPC 157 (10ng, 10μg ip, complete counteraction), l-arginine (100mg ip, attenuation) vs. L-NAME (5mg ip, deadly aggravation), given alone and/or combined, before or after intraperitoneal KCl-solution application (9mEq/kg). Therapy was confronted with promptly unrelenting hyperkalemia (>12mmol/L), arrhythmias (and muscular weakness, hypertension, low pressure in lower esophageal and pyloric sphincter) with an ultimate and a regularly inevitable lethal outcome within 30min. Previously, we established BPC 157-NO-system interaction; now, a huge life-saving potential. Given 30min before KCl, all BPC 157 regimens regained sinus rhythm, had less prolongation of QRS, and had no asystolic pause. BPC 157 therapy, given 10min after KCl-application, starts the rescue within 5-10min, completely restoring normal sinus rhythm at 1h. Likewise, other hyperkalemia-disturbances (muscular weakness, hypertension, low sphincteric pressure) were also counteracted. Accordingly with NO-system relation, deadly aggravation by L-NAME: l-arginine brings the values to the control levels while BPC 157 always completely nullified lesions, markedly below those of controls. Combined with l-arginine, BPC 157 exhibited no additive effect. (ii) Intragastric KCl-solution application (27mEq/kg) - (hyperkalemia 7mmol/L): severe stomach mucosal lesions, sphincter failure and peaked T waves were fully counteracted by intragastric BPC 157 (10ng, 10μg) application, given 30min before or 10min after KCl. (iii). In HEK293 cells, hyperkalemic conditions (18.6mM potassium concentrations), BPC 157 directly affects potassium conductance, counteracting the effect on membrane potential and depolarizations caused by hyperkalemic conditions.

Rapid response team interventions for severe hyperkalemia: evaluation of a patient safety initiative

RATIONALE

This study evaluates outcomes and process measures associated with a rapid response team (RRT) intervention for patients with severe hyperkalemia.

STUDY POPULATION

Inpatients on medical-surgical floors (excluding dialysis or comfort care patients) at a 1000-bed tertiary hospital from 2005 to 2009 with severe hyperkalemia (defined as potassium [K(+)] ≥ 6.3 mEq/L).

METHODS

Retrospective administrative data and medical record review. Hyperkalemia incidence (based both on coding data and laboratory test results) was assessed, as was the association between hyperkalemia and mortality. Independent physician reviewers adjudicated selected cases for death directly attributable to hyperkalemia and potential for preventability with the RRT intervention. All 115 Baylor University Medical Center (Dallas, TX) cases receiving the RRT hyperkalemia intervention over a 12-month period (December 2006-December 2007) underwent in-depth process assessment.

RESULTS

Hyperkalemia occurred as a codable diagnosis in approximately 3.2% of all hospital discharges annually (5-year average of 42 000 discharges), and K(+) values ≥ 6.3 mEq/L were observed in 0.8% to 0.9% of all K(+) assays run by the laboratory in the months sampled. Deaths determined to be directly related to hyperkalemia and potentially preventable were rare, with a total of only 4 events during the study period (3 of these were in the pre-implementation phase), precluding statistical analysis on mortality related to the intervention. The RRT averaged 6 to 10 interventions for hyperkalemia monthly (representing 10% of all inpatient K(+) values ≥ 6.3 mEq/L). Mean initial K(+) level triggering the RRT cascade was 6.7 ± 0.3 mEq/L; average time from floor notification of critical K(+) level to bedside RRT arrival was 14.6 ± 12.1 minutes. Over 24 to 36 hours, K(+) declined 1.7 ± 1.1 mEq/L between patients' initial and final K(+) values (P < 0.001).

CONCLUSIONS

Hyperkalemia occurs frequently in inpatient settings. Rapid response team intervention for this condition facilitates timely correction of critical laboratory test results and consistent treatment through use of a standardized protocol. Benefit of the intervention on mortality could not be reliably demonstrated in this study due to event rarity and challenges with case ascertainment. Further research with a prospective, multi-site cluster design using electronic medical records and larger sample sizes could demonstrate which RRT hyperkalemia intervention components warrant widespread adoption.

Hyperkalemia accompanies hemorrhagic shock and correlates with mortality

OBJECTIVE

This study was designed to evaluate the effects of terlipressin versus fluid resuscitation with normal saline, hypertonic saline or hypertonic-hyperoncotic hydroxyethyl starch, on hemodynamics, metabolics, blood loss and short-term survival in hemorrhagic shock.

METHOD

Twenty-nine pigs were subjected to severe liver injury and treated 30 min later with either: (1) 2 mg terlipressin in a bolus, (2) placebo-treated controls, (3) 4 mL/kg 7.5% hypertonic NaCl, (4) 4 mL/kg 7.2% hypertonic-hyperoncotic hydroxyethyl starch 200/0.5, or (5) normal saline at three times lost blood volume.

RESULTS

The overall mortality rate was 69%. Blood loss was significantly higher in the hypertonic-hyperoncotic hydroxyethyl starch and normal saline groups than in the terlipressin, hypertonic NaCl and placebo-treated controls groups (p<0.005). Hyperkalemia (K>5 mmol/L) before any treatment occurred in 66% of the patients (80% among non-survivors vs. 22% among survivors, p=0.019). Post-resuscitation hyperkalemia occurred in 86.66% of non-survivors vs. 0% of survivors (p<0.001). Hyperkalemia was the first sign of an unsuccessful outcome for the usual resuscitative procedure and was not related to arterial acidemia. Successfully resuscitated animals showed a significant decrease in serum potassium levels relative to the baseline value.

CONCLUSION

Hyperkalemia accompanies hemorrhagic shock and, in addition to providing an early sign of the acute ischemic insult severity, may be responsible for cardiac arrest related to hemorrhagic shock.

[Acute renal failure. Extracorporeal therapy]

Acute renal failure is increasingly found in critically ill patients as part of the multiple organ dysfunction syndrome. Intermittent hemodialysis and continuous renal replacement therapy are standard extracorporeal replacement therapies. Continuous therapies are thought to be especially useful in cardiovascularly instable patients in the intensive care unit. Recently, slow, extended daily dialysis was introduced as a hybrid method, combining the advantages of intermittent and continuous renal replacement therapy. While controlled studies have uniformly shown that a high dose of such replacement therapy increases survival, studies have failed to support a definitive advantage for any method in terms of patient survival. Therefore, the choice of renal replacement therapy should be based on personal experience, the available resources/infrastructure as well as the needs of the individual patient.

The Effect of Calcium Chloride in Treating Hyperkalemia Due to Acute Digoxin Toxicity in a Porcine Model

BACKGROUND

The administration of intravenous (IV) calcium to treat hyperkalemia resulting from digoxin poisoning is considered potentially dangerous, based on a body of older literature which, in sum, reported increased cardiac glycoside toxicity with calcium administration (increased arrhythmias, higher rate of death).

OBJECTIVE

This pilot study sought to determine if the administration of calcium chloride when compared to normal saline would affect time to death when given to hyperkalemic, digoxin toxic swine.

METHODS

Digoxin IV at 0.25 mg/kg was determined to be appropriately toxic for this study. When arrhythmias consistent with hyperkalemia developed, animals were given either IV calcium chloride (CaCl) bolus (10 mg/kg, Group 1, n=6) or normal saline volume equivalent (Group 2, n=6). Three intervals were observed: Interval 1: time interval from digoxin administration (T0) to when ECG changes consistent with hyperkalemia developed (at which point calcium chloride or normal saline was administered); Interval 2: time interval from the development of ECG changes consistent with hyperkalemia to asystole; Interval 3: time interval from digoxin administration to asystole. Both groups were monitored for changes in heart rhythms, serum potassium levels, and time to asystole.

RESULTS

The intravenous digoxin dose of 0.25 mg/kg induced hyperkalemia, arrhythmias, and death approximately 1 h after administration in all animals studied. Group 1: Interval 1 averaged 18.75 (S.D. +/-7.96) min, Interval 2 averaged 16.75 (S.D. +/-17.17) min, and Interval 3 averaged 35.5 (S.D. +/-14.49) min range; Group 2: average Interval 1 24.8 (S.D. +/-4.71) min, Interval 2 averaged 19.5 (S.D.+/-15.92), Interval 3 averaged 44.3 (S.D. +/-13.80) minutes. There was no statistically significant difference between the groups at any time interval, Interval 1 (p=0.43), Interval 2 (p=0.65), Interval 3 (p=0.40). There was no difference in serum potassium throughout the study period.

CONCLUSION

The administration of intravenous CaCl in the setting of hyperkalemia from acute digoxin toxicity did not affect mortality or time to death at the dose administered.

Rates of hyperkalemia after publication of the Randomized Aldactone Evaluation Study

BACKGROUND

The Randomized Aldactone Evaluation Study (RALES) demonstrated that spironolactone significantly improves outcomes in patients with severe heart failure. Use of angiotensin-converting-enzyme (ACE) inhibitors is also indicated in these patients. However, life-threatening hyperkalemia can occur when these drugs are used together.

METHODS

We conducted a population-based time-series analysis to examine trends in the rate of spironolactone prescriptions and the rate of hospitalization for hyperkalemia in ambulatory patients before and after the publication of RALES. We linked prescription-claims data and hospital-admission records for more than 1.3 million adults 66 years of age or older in Ontario, Canada, for the period from 1994 through 2001.

RESULTS

Among patients treated with ACE inhibitors who had recently been hospitalized for heart failure, the spironolactone-prescription rate was 34 per 1000 patients in 1994, and it increased immediately after the publication of RALES, to 149 per 1000 patients by late 2001 (P<0.001). The rate of hospitalization for hyperkalemia rose from 2.4 per 1000 patients in 1994 to 11.0 per 1000 patients in 2001 (P<0.001), and the associated mortality rose from 0.3 per 1000 to 2.0 per 1000 patients (P<0.001). As compared with expected numbers of events, there were 560 (95 percent confidence interval, 285 to 754) additional hyperkalemia-related hospitalizations and 73 (95 percent confidence interval, 27 to 120) additional hospital deaths during 2001 among older patients with heart failure who were treated with ACE inhibitors in Ontario. Publication of RALES was not associated with significant decreases in the rates of readmission for heart failure or death from all causes.

CONCLUSIONS

The publication of RALES was associated with abrupt increases in the rate of prescriptions for spironolactone and in hyperkalemia-associated morbidity and mortality. Closer laboratory monitoring and more judicious use of spironolactone may reduce the occurrence of this complication.

Learning and memory is preserved after induced asanguineous hyperkalemic hypothermic arrest in a swine model of traumatic exsanguination

BACKGROUND

Induced asanguineous hypothermic metabolic arrest (suspended animation) could provide valuable time to repair major vascular injuries if safely induced in patients with trauma. We report a novel method of doing this in a swine model of uncontrolled lethal hemorrhage (ULH) that resulted in preservation of learning ability and memory.

METHODS

Yorkshire swine (100 to 125 lb) underwent ULH before rapid intra-aortic infusion of a hypothermic (4 degrees C), hyperkalemic (70 mEq/L) organ preservation solution by a left thoracotomy. Cooling continued until core temperature reached 10 degrees C, and this was maintained for 60 minutes using low-flow cardiopulmonary bypass. Vascular injuries were repaired during this state of suspended animation, which was then reversed, and the animals were observed for 6 weeks. Cognitive functions were tested by training animals to retrieve food from color-coded boxes. Postoperatively, the ability to remember this task and a 75-point objective neurologic scale were used to test neurologic function. In experiment I, ULH was caused by lacerating thoracic aorta (n = 9). Five preoperatively untrained animals were trained to perform the task and compared with control animals (n = 15), and 4 preoperatively trained animals were tested for memory retention postoperatively. In experiment II, ULH was induced by creating an iliac artery and vein injury (n = 15). Animals were kept in shock for 15, 30, and 60 minutes before the induction of hypothermia.

RESULTS

In experiment I, surviving animals (7/9) were neurologically intact, and their capacity to learn new skills was no different than for control animals. All pretrained animals demonstrated complete memory retention. In experiment II, survival with 15, 30, and 60 minutes of shock were 80%, 60%, and 80%, respectively. All animals (except 1) in the 60-minute group were neurologically intact and displayed normal learning capacity.

CONCLUSIONS

Induction of hypothermic metabolic arrest (by thoracotomy) for repair of complex traumatic injuries is feasible with preservation of normal neurologic function, even after extended periods of shock from an intra-abdominal source of uncontrolled hemorrhage.

Life-threatening hyperkalemia during combined therapy with angiotensin-converting enzyme inhibitors and spironolactone: an analysis of 25 cases

PURPOSE

The beneficial effects of spironolactone are additive to those of ACE inhibitors among patients with heart failure and/or hypertension; however, it is essential to identify patients prone to develop serious hyperkalemia during combined treatment and to evaluate the associated morbidity and mortality.

SUBJECTS AND METHODS

We studied 25 patients treated with ACE inhibitors and spironolactone who were admitted to the emergency room with a serum potassium level > 6 mmol/L. Patients were followed up for at least one month after admission.

RESULTS

The mean age of the patients (11 males, 14 females) was 74 +/- 13 years. Five patients were diabetics. On admission, the serum potassium was 7.7 +/- 0.7 mmol/L and the serum creatinine was 3.8 +/- 1.8 mg/dL; these values were significantly higher than the most recent follow-up laboratory measurements (4.6 +/- 0.5 mmol/L and 1.9 +/- 1.2 mg/dL, respectively) obtained at 13 +/- 5 weeks before admission. The arterial pH on admission was 7.3 +/- 0.1 and the plasma bicarbonate was 18 +/- 5 mmol/L. The main causes for acute renal failure were dehydration (n = 12) and worsening heart failure (n = 9). The mean daily dose of spironolactone was 57 +/- 32 mg and 12 patients were concomitantly treated with other drugs that may cause hyperkalemia. Two patients died, and 2 patients were resuscitated but survived. Hemodialysis was necessary in 17 patients; 12 patients were admitted to the intensive care unit. The mean duration of hospitalization was 12 +/- 6 days. Two patients needed to be started on maintenance hemodialysis therapy.

CONCLUSION

A combination of ACE inhibitors and spironolactone should be considered with caution and monitored closely in patients with renal insufficiency, diabetes, older age, worsening heart failure, a risk for dehydration, and in combination with other medications that may cause hyperkalemia. A daily spironolactone dose of 25 mg should not be exceeded.

Glucose and insulin infusion versus kayexalate for the early treatment of non-oliguric hyperkalemia in very-low-birth-weight infants

Forty very low birth weight (VLBW) infants with non-oliguric hyperkalemia in the first few days after birth were enrolled in this study. They were randomly divided into 2 groups, regular insulin (RI) infusion group and kayexalate resin enema group. Therapy was administered when serum potassium level was greater than 6 mEq/L. None of these infants received blood transfusion during this study course. In RI group (n = 20), the ratio of infusion glucose to regular insulin was 10-15 gm glucose to 1 unit RI, and the glucose infusion rate was maintained at least 6 mg/Kg/min. In Kayexalate group (n = 20), the dose of Kayexalate was 1 gm/Kg body weight given rectally every four hours. All treatment discontinued after the serum potassium level returned to normal for 6 hours. The mean gestational ages were 27.4 +/- 1.8 weeks in RI group and 28.4 +/- 2.4 weeks in Kayexalate group, respectively. Mean birth weights were 935 +/- 259 gm (RI) and 1065 +/- 214 gm (Kayexalate). The ages at onset of hyperkalemia were 24.6 +/- 8.2 (RI) and 22.2 +/- 8.1 (Kayexalate) hours after birth. The mean urine outputs during the 8-hour interval prior to development of hyperkalemia were 5.4 +/- 1.3 (RI) and 5.5 +/- 0.9 (Kayexalate) ml/kg/min. The durations of hyperkalemia were 26.4 +/- 14.9 (RI) and 38.6 +/- 13.3 (Kayexalate) hours. The peak serum potassium levels during therapy were 7.3 +/- 0.9 and 7.4 +/- 0.6 mEq/L. The incidences of grade II and above intraventricular hemorrhage (IVH) were 15% (3/20) and 50% (10/20). The incidences of cardiac dysrhythmia were 5% (1/20) and 10% (2/20). Significantly shorter duration of non-oliguric hyperkalemia and lower incidence of IVH were noted in RI group, but there were no differences in the peak potassium level or the incidence of cardiac dysrhythmia between these two groups. We conclude that to use early continuous regular insulin infusion therapy for the treatment of non-oliguric hyperkalemia in VLBW infants is more effective than kayexalate in decreasing the duration of hyperkalemia and reducing the incidence of intraventricular hemorrhage.

Hyperkalemia in outpatients using angiotensin-converting enzyme inhibitors. How much should we worry?

BACKGROUND

Hyperkalemia is a potentially life-threatening complication resulting from the use of angiotensin-converting enzyme (ACE) inhibitors; data to guide the intensity of monitoring for or responding to hyperkalemia in outpatients are limited.

METHODS

Case-control methodological procedures were used to identify risk factors for hyperkalemia. Outpatients prescribed ACE inhibitors during 1992 and 1993 at a Veterans Affairs medical center general medicine clinic were identified. Case patients had a potassium level higher than 5.1 mmol/L on the day of clinic visit while using an ACE inhibitor; controls had a potassium level lower than 5.0 mmol/L on the day of clinic visit while using an ACE inhibitor and had no elevated potassium level during the study period. Predictor variables measured included type and dosage of ACE inhibitor; serum chemistries; comorbidities; concurrent drug use; and age. Case patients were followed up for 1 year after the index episode of hyperkalemia. Follow-up variables included changes in therapy with ACE inhibitor, maximum potassium for each change, and mortality.

RESULTS

Of 1818 patients using ACE inhibitors, 194 (11%) developed hyperkalemia. Results of laboratory studies indicating a serum urea nitrogen level higher than 6.4 mmol/L (18 mg/dL), creatinine level higher than 136 mumol/L (1.5 mg/dL), congestive heart failure, and long-acting ACE inhibitors were independently associated with hyperkalemia; concurrent use of loop or thiazide diuretic agent was associated with reduced risk. After 1 year of follow-up, 15 (10%) of 146 case patients remaining on a regimen of an ACE inhibitor developed severe hyperkalemia (potassium level > 6.0 mmol/L). A serum urea nitrogen level higher than 8.9 mmol/L (25 mg/dL) and age more than 70 years were independently associated with subsequent severe hyperkalemia.

CONCLUSIONS

Mild hyperkalemia is common in medical outpatients using ACE inhibitors, especially in those with renal insufficiency or congestive heart failure. However, once hyperkalemia is identified during the use of ACE inhibitors, subsequent severe hyperkalemia is uncommon in patients younger than 70 years with normal renal function.

Rapid life-threatening hyperkalemia after addition of amiloride HCl/hydrochlorothiazide to angiotensin-converting enzyme inhibitor therapy

STUDY OBJECTIVE

To highlight the dangers of a precipitous rise in serum potassium levels in patients at risk for renal insufficiency, already receiving an angiotensin-converting enzyme (ACE) inhibitor, who are given a potassium-sparing diuretic.

METHODS

We conducted a retrospective chart review of five patients who were taking the above combination of medications who were seen in our ED with hyperkalemia.

RESULTS

All five patients had diabetes and were older than 50 years of age. Except for one patient, they had some degree of renal impairment and all were receiving an ACE inhibitor. Each had amiloride HCl/hydrochlorothiazide added to their therapeutic regimen 8 to 18 days before presenting to our ED with hyperkalemia. Potassium levels were between 9.4 and 11 mEq/L in 4 of the patients; 2 did not respond to resuscitation measures.

CONCLUSION

The concomitant use of ACE inhibitor and potassium-sparing diuretic therapy should be avoided. If impossible, weekly monitoring of both renal function and serum potassium should be performed. In the ED patients who are receiving such a combination should receive immediate ECG monitoring.

Serum potassium, cigarette smoking, and mortality in middle-aged men

The relation between serum potassium level and all-cause mortality was examined in a prospective study of 7,636 middle-aged British men followed for 11.5 years (1978-1991). Men being treated for hypertension had a significantly lower mean (+/- standard error) potassium level than men not in treatment (4.24 +/- 0.03 mmol/liter vs. 4.32 +/- 0.01 mmol/liter; p < 0.01). During the follow-up period of 11.5 years, after exclusion of the 374 men under antihypertensive treatment, there were 771 deaths from all causes in the remaining 7,262 men. A low potassium level (< 3.7 mmol/liter) was not associated with increased mortality. Elevated potassium levels > or = 5.2 mmol/liter were associated with a significant increase in mortality, particularly noncardiovascular deaths, even after adjustment for potentially confounding factors. However, serum potassium was strongly related to smoking, and the increased risk of mortality associated with elevated potassium was seen only among current smokers. In current smokers with raised potassium levels (> or = 5.2 mmol/liter) compared with smokers with levels under 5.2 mmol/liter, the relative risks of mortality were 1.7 (95% confidence interval (CI) 1.2-2.5) for deaths from all causes, 1.8 (95% CI 1.0-3.2) for all cancer deaths, and 2.5 (95% CI 1.1-5.6) for lung cancer deaths. In the 374 men receiving regular antihypertensive treatment, a low potassium level was not associated with excess mortality; those with raised potassium levels had excess risks for both cardiovascular and noncardiovascular deaths. The findings suggest that either raised potassium levels in association with smoking have an influence on the risk of death from noncardiovascular disease, particularly lung cancer, or a raised serum potassium level is a marker for some other risk factor associated with smoking. The prognostic and therapeutic implications of these observations warrant further exploration.

Hyperkalaemia in patients in hospital

A survey of all laboratory blood specimens with a plasma potassium concentration greater than or equal to 5.5 mmol/L was conducted over a three month period. Of 331 specimens with hyperkalaemia, 71 were excluded because the specimens was haemolysed, old or contaminated. The laboratory served a population of 348,561 and during this time measured the plasma potassium on 25,016 occasions. Sixty-six outpatients and 20 neonates were not evaluated. The survey was undertaken on 86 of 102 inpatients (46 males), 48 of whom were over 66 years of age. Fifty-seven patients were admitted under a medical service and 29 under a surgical service. Fifty-nine had a single episode of hyperkalaemia. Thirty-two underwent a surgical procedure. The commonest contributing factor was impaired renal function which was present in 71 (83%) patients. Although a definitive causative role for drugs could be identified in only five patients, in 52 (60%) patients drugs were a contributing factor (potassium supplements 24, ACE inhibitors 16, nonsteroidal antiinflammatory drugs 12). Thirty-five of the 86 (41%) patients died during their hospital admission. Nineteen of the 35 deaths occurred within three days of the hyperkalaemia being recorded. A normal plasma potassium was eventually documented in 50 of the 86 patients. Of the remaining 36 patients, 25 (69%) subsequently died. In general the treatment of patients with hyperkalaemia focused on identifying and treating the underlying cause. Hyperkalaemia must always be considered seriously and regard given to the overall clinical status of the patient, with particular attention to drug therapy, renal and cardiac function, acid base status and the possibility of sepsis.

Hyperlactataemia, hyperkalemia and heart block in acute iron overload: the fatal role of the hepatic iron-incorporation rate in rats on ferric citrate infusions

An animal model is presented that provides constant and controllable conditions for approaching gradually, and within reasonable time, different stages of iron overload and, probably, an iron-induced mitochondrial disorder. Thirty-five rats were infused with ferric citrate, sodium citrate and saline at constant rates for 6-24 h. In the 200-3200 micrograms Fe h-1 loading range, the iron-incorporation capacity of the liver was not saturable and the fractional iron uptake by the liver remained at approximately 30% even at a loading rate of 3200 micrograms Fe h-1. Up to a loading rate of 200 micrograms Fe h-1, iron storage was not associated with toxic effects. Beyond this loading rate, however, the liver was no longer able to prevent a massive plasma iron increase on one side and hyperlactataemia on the other. These signs most probably represent hepatocellular decompensation with respect to a critical iron-storage rate. The product of plasma iron x exposition time was significantly correlated with increased plasma lactate levels (r = 0.89, P less than 0.005), whereas increased plasma iron levels per se were not. Hyperlactataemia was associated with hyperkalaemia and progressive cardiac conduction defects leading to cardiac arrest at lactate concentration of 9.1 +/- 4.3 mmol l-1. The hypothesis is discussed that toxicity in acute iron overload may entirely be due to hepatocellular (mitochondrial) damage, and not to multiple organ iron overload.

Early onset hyperkalemia in extremely low birth weight infants

The incidence of hyperkalemia and associated clinical features in extremely preterm infants were determined by reviewing medical records of 32 infants with birth weights of less than or equal to 800 g born during a 1-year period. Hyperkalemia, defined as serum potassium concentration of greater than 6.5 mEq/L, occurred in 12 infants on the first day of life and in four others on the second day. Six infants (38%) had electrocardiographic abnormalities associated with hyperkalemia. Infants with hyperkalemia were less mature than infants with normal potassium levels. All infants of less than 25 weeks' gestation developed hyperkalemia. Fluid intakes and urine flow rates were lower and body weight loss greater during the first 24 hours of hospitalization for hyperkalemic infants. Hyperkalemia frequently occurs within the first 48 hours of life in extremely immature infants. Serum potassium should be monitored closely to avoid life-threatening cardiac arrhythmias in these infants.

Prognostic factors in severe accidental hypothermia: experience from the Mt. Hood tragedy

The May 1986 Mt. Hood climbing disaster presented Portland area hospitals the opportunity to initiate a trial of extracorporeal rewarming using cardiopulmonary bypass in ten severely hypothermic patients (two survivors). The data from this experience as well as others previously reported can yield prognostic indicators of survival in cases of accidental hypothermia. These are demonstrated to include: the presence of underlying medical illness, duration of cold exposure, initial core temperature, mental status, the presence of spontaneous respirations, presenting cardiac rate and rhythm, and arterial oxygen tension. Profound hyperkalemia and markedly elevated serum ammonia levels indicate cell lysis; significant hypofibrinogenemia suggests intravascular thrombosis and each laboratory marker predicts a dire outcome. The treatment of choice for severe accidental hypothermia is felt to be rapid core rewarming on cardiopulmonary bypass.