Combining pharmacokinetic and electrophysiological models for early prediction of drug-induced arrhythmogenicity

BACKGROUND AND OBJECTIVE

In silico methods are gaining attention for predicting drug-induced Torsade de Pointes (TdP) in different stages of drug development. However, many computational models tended not to account for inter-individual response variability due to demographic covariates, such as sex, or physiologic covariates, such as renal function, which may be crucial when predicting TdP. This study aims to compare the effects of drugs in male and female populations with normal and impaired renal function using in silico methods.

METHODS

Pharmacokinetic models considering sex and renal function as covariates were implemented from data published in pharmacokinetic studies. Drug effects were simulated using an electrophysiologically calibrated population of cellular models of 300 males and 300 females. The population of models was built by modifying the endocardial action potential model published by O'Hara et al. (2011) according to the experimentally measured gene expression levels of 12 ion channels.

RESULTS

Fifteen pharmacokinetic models for CiPA drugs were implemented and validated in this study. Eight pharmacokinetic models included the effect of renal function and four the effect of sex. The mean difference in action potential duration (APD) between male and female populations was 24.9 ms (p<0.05). Our simulations indicated that women with impaired renal function were particularly susceptible to drug-induced arrhythmias, whereas healthy men were less prone to TdP. Differences between patient groups were more pronounced for high TdP-risk drugs. The proposed in silico tool also revealed that individuals with impaired renal function, electrophysiologically simulated with hyperkalemia (extracellular potassium concentration [K+]o = 7 mM) exhibited less pronounced APD prolongation than individuals with normal potassium levels. The pharmacokinetic/electrophysiological framework was used to determine the maximum safe dose of dofetilide in different patient groups. As a proof of concept, 3D simulations were also run for dofetilide obtaining QT prolongation in accordance with previously reported clinical values.

CONCLUSIONS

This study presents a novel methodology that combines pharmacokinetic and electrophysiological models to incorporate the effects of sex and renal function into in silico drug simulations and highlights their impact on TdP-risk assessment. Furthermore, it may also help inform maximum dose regimens that ensure TdP-related safety in a specific sub-population of patients.

Impact of Sodium Zirconium Cyclosilicate Plus Renin-Angiotensin-Aldosterone System Inhibitor Therapy on Short-Term Medical Costs in Hyperkalemia: OPTIMIZE II Real-World Study

INTRODUCTION

Patients receiving cardiorenal-protective renin-angiotensin-aldosterone system inhibitors (RAASis) are at increased risk of developing hyperkalemia, which is associated with increased medical costs. The aim of this study was to evaluate the impact of adding sodium zirconium cyclosilicate (SZC) therapy on 3-month medical costs in patients who experienced hyperkalemia while receiving RAASi therapy.

METHODS

The retrospective OPTIMIZE II study used medical and pharmacy claims data from IQVIA PharMetrics® Plus. Patients aged ≥ 18 years who received SZC (≥ 60 day supply over 3 months' follow-up) and continued RAASi between July 2019 and December 2021 (Continue RAASi + SZC cohort) were 1:1 exact and propensity score matched with patients who discontinued RAASi after hyperkalemia diagnosis and did not receive SZC (Discontinue RAASi + no SZC cohort). The primary outcome was hyperkalemia-related medical costs to payers over 3 months; all-cause medical and pharmacy costs were also analyzed.

RESULTS

In the Continue RAASi + SZC (n = 467) versus Discontinue RAASi + no SZC (n = 467) cohort, there were significant reductions in mean per-patient hyperkalemia-related medical costs (reduction of $2216.07; p = 0.01) and all-cause medical costs (reduction of $6102.43; p < 0.001); mean hyperkalemia-related inpatient medical costs and all-cause inpatient and emergency department medical costs were significantly reduced. The reduction in all-cause medical cost in the Continue RAASi + SZC cohort offset an increase in the mean per-patient all-cause pharmacy cost (increase of $3117.71; p < 0.001).

CONCLUSION

RAASi therapy has well-established cardiorenal benefits. In OPTIMIZE II, management of RAASi-induced hyperkalemia with SZC was associated with lower hyperkalemia-related and all-cause medical costs than RAASi discontinuation without SZC, demonstrating medical cost savings with maintaining RAASi therapy with SZC.

Decision support system for NPK fertilization: a solution method for minimizing the impact on human health, climate change, ecosystem quality and resources

Sugarcane cultivation requires correct fertilizer rates. However, when nutrients are not available, or there is over-fertilization, the yields are significantly reduced and the environmental burden increase. In this study, it is proposed a decision support system (DSS) for the correct NPK (nitrogen, phosphorus and potassium) fertilization. The DSS consists of two fuzzy models; the edaphic condition model (EDC-M) and the NPK fertilization model (NPK-M). The DSS using parameters from soil analysis and is based on the experience of two groups of experts to avoid the bias to the reality of a single group of professionals. The results of the DSS are compared with the results of soil analysis and those of the group of experts. One hundred and sixty tests were developed in the NPK-M. The N rate shows R ²=0.981 for the DSS and R ²=0.963 for soil analyzes. The P rate shows R ²=0.9702 for the DSS and R ²=0.9183 for the soil analyzes. The K rate shows R ²=0.9691 for the DSS and R ²=0.9663 for the soil analyzes. Environmental results indicate that the estimated rates with the DSS do reduce the environmental impact on the tests performed.

Modified Glucose-Insulin-Potassium Regimen Provides Cardioprotection With Improved Tissue Perfusion in Patients Undergoing Cardiopulmonary Bypass Surgery

Background Laboratory studies demonstrate glucose-insulin-potassium (GIK) as a potent cardioprotective intervention, but clinical trials have yielded mixed results, likely because of varying formulas and timing of GIK treatment and different clinical settings. This study sought to evaluate the effects of modified GIK regimen given perioperatively with an insulin-glucose ratio of 1:3 in patients undergoing cardiopulmonary bypass surgery. Methods and Results In this prospective, randomized, double-blinded trial with 930 patients referred for cardiac surgery with cardiopulmonary bypass, GIK (200 g/L glucose, 66.7 U/L insulin, and 80 mmol/L KCl) or placebo treatment was administered intravenously at 1 mL/kg per hour 10 minutes before anesthesia and continuously for 12.5 hours. The primary outcome was the incidence of in-hospital major adverse cardiac events including all-cause death, low cardiac output syndrome, acute myocardial infarction, cardiac arrest with successful resuscitation, congestive heart failure, and arrhythmia. GIK therapy reduced the incidence of major adverse cardiac events and enhanced cardiac function recovery without increasing perioperative blood glucose compared with the control group. Mechanistically, this treatment resulted in increased glucose uptake and less lactate excretion calculated by the differences between arterial and coronary sinus, and increased phosphorylation of insulin receptor substrate-1 and protein kinase B in the hearts of GIK-treated patients. Systemic blood lactate was also reduced in GIK-treated patients during cardiopulmonary bypass surgery. Conclusions A modified GIK regimen administered perioperatively reduces the incidence of in-hospital major adverse cardiac events in patients undergoing cardiopulmonary bypass surgery. These benefits are likely a result of enhanced systemic tissue perfusion and improved myocardial metabolism via activation of insulin signaling by GIK. Clinical Trial Registration URL: clinicaltrials.gov. Identifier: NCT01516138.

Melatonin receptor activation protects against low potassium-induced ventricular fibrillation by preserving action potentials and connexin-43 topology in isolated rat hearts

Hypokalemia prolongs the QRS and QT intervals, deteriorates intercellular coupling, and increases the risk for arrhythmia. Melatonin preserves gap junctions and shortens action potential as potential antiarrhythmic mechanisms, but its properties under hypokalemia remain unknown. We hypothesized that melatonin protects against low potassium-induced arrhythmias through the activation of its receptors, resulting in action potential shortening and connexin-43 preservation. After stabilization in Krebs-Henseleit solution (4.5 mEq/L K⁺ ), isolated hearts from Wistar rats underwent perfusion with low-potassium (1 mEq/L) solution and melatonin (100 μmol/L), a melatonin receptor blocker (luzindole, 5 μmol/L), melatonin + luzindole or vehicle. The primary endpoint of the study was the prevention of ventricular fibrillation. Electrocardiography was used, and epicardial action potentials and heart function were measured and analyzed. The ventricular expression, dephosphorylation, and distribution of connexin-43 were examined. Melatonin reduced the incidence of low potassium-induced ventricular fibrillation from 100% to 59%, delayed the occurrence of ventricular fibrillation and induced a faster recovery of sinus rhythm during potassium restitution. Melatonin prevented QRS widening, action potential activation delay, and the prolongation of action potential duration at 50% of repolarization. Other ECG and action potential parameters, the left ventricular developed pressure, and nonsustained ventricular arrhythmias did not differ among groups. Melatonin prevented connexin-43 dephosphorylation and its abnormal topology (lateralization). Luzindole abrogated the protective effects of melatonin on electrophysiological properties and connexin-43 misdistribution. Our results indicate that melatonin receptor activation protects against low potassium-induced ventricular fibrillation, shortens action potential duration, preserves ventricular electrical activation, and prevents acute changes in connexin-43 distribution. All of these properties make melatonin a remarkable antifibrillatory agent.

Potassium supplementation and heart rate: A meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Increasing the intake of potassium has been shown to lower blood pressure, but whether it also affects heart rate (HR) is largely unknown. We therefore assessed the effect of potassium supplementation on HR in a meta-analysis of randomized controlled trials.

METHODS AND RESULTS

We searched PubMed (1966-October 2014) for randomized, placebo-controlled trials in healthy adults with a minimum duration of two weeks in which the effect of increased potassium intake on HR was assessed. In addition, reference lists from meta-analysis papers on potassium and blood pressure were hand-searched for publications. Two investigators independently extracted the data. We performed random effects meta-analyses, subgroup and meta-regression analyses for characteristics of the study (e.g. design, intervention duration, potassium dose and salt type, change in potassium excretion, sodium excretion during intervention) and study population (e.g. gender, age, hypertensive status, pre-study HR, pre-study potassium excretion). A total of 22 trials (1086 subjects), with a median potassium dose of 2.5 g/day (range: 0.9-4.7 g/day), and median intervention duration of 4 weeks (range: 2-24 weeks) were included. The meta-analysis showed no overall effect of increased potassium intake on HR (0.19 bpm, 95% CI: -0.44, 0.82). Stratified analyses yielded no significant effects of potassium intake on HR in subgroups, and there was no evidence for a dose-response relationship in meta-regression analyses.

CONCLUSION

A chronic increase in potassium intake with supplemental doses of 2-3 g/day is unlikely to affect HR in apparently healthy adults.

Does Hemodialysis Dialysate Potassium Composition Matter?

Dyskalemia is known to cause cardiac arrhythmias and cardiac arrest. In persons undergoing hemodialysis, potassium dialysate composition has been identified as a contributingfactor in addition to co-morbidities, medications, dietary potassium intake, and stage of kidney disease. Current evidence recommends a thorough evaluation of all factors affecting potassium balance, and lower potassium concentration should be used cautiously in patients who are likely to develop cardiac arrhythmias. Nephrology nurses play a key role inpatient assessment and edu- cation related to potassium balance.

Emergency Department Visits for Adverse Events Related to Dietary Supplements

BACKGROUND

Dietary supplements, such as herbal or complementary nutritional products and micronutrients (vitamins and minerals), are commonly used in the United States, yet national data on adverse effects are limited.

METHODS

We used nationally representative surveillance data from 63 emergency departments obtained from 2004 through 2013 to describe visits to U.S. emergency departments because of adverse events related to dietary supplements.

RESULTS

On the basis of 3667 cases, we estimated that 23,005 (95% confidence interval [CI], 18,611 to 27,398) emergency department visits per year were attributed to adverse events related to dietary supplements. These visits resulted in an estimated 2154 hospitalizations (95% CI, 1342 to 2967) annually. Such visits frequently involved young adults between the ages of 20 and 34 years (28.0% of visits; 95% CI, 25.1 to 30.8) and unsupervised children (21.2% of visits; 95% CI, 18.4 to 24.0). After the exclusion of unsupervised ingestion of dietary supplements by children, 65.9% (95% CI, 63.2 to 68.5) of emergency department visits for single-supplement-related adverse events involved herbal or complementary nutritional products; 31.8% (95% CI, 29.2 to 34.3) involved micronutrients. Herbal or complementary nutritional products for weight loss (25.5%; 95% CI, 23.1 to 27.9) and increased energy (10.0%; 95% CI, 8.0 to 11.9) were commonly implicated. Weight-loss or energy products caused 71.8% (95% CI, 67.6 to 76.1) of supplement-related adverse events involving palpitations, chest pain, or tachycardia, and 58.0% (95% CI, 52.2 to 63.7) involved persons 20 to 34 years of age. Among adults 65 years of age or older, choking or pill-induced dysphagia or globus caused 37.6% (95% CI, 29.1 to 46.2) of all emergency department visits for supplement-related adverse events; micronutrients were implicated in 83.1% (95% CI, 73.3 to 92.9) of these visits.

CONCLUSIONS

An estimated 23,000 emergency department visits in the United States every year are attributed to adverse events related to dietary supplements. Such visits commonly involve cardiovascular manifestations from weight-loss or energy products among young adults and swallowing problems, often associated with micronutrients, among older adults. (Funded by the Department of Health and Human Services.).

[Irradiation doses of population in mountainous Adjara region of Georgia]

Radionuclide content of food and water in high mountainous regions of Georgia - Adjara (Keda, Shuakhevi, Khulo) has been studied, internal and total irradiation doses for the population have been defined and preventive measures for its reduction have been proposed. Internal irradiation dose for the population caused by K-40 was identified as 0,63 mSv/y, total irradiation dose - 1,73 mSv/y, that slightly exceeds acceptable levels, due to this it seems desirable to provide some measures with aim to reduce the radiation dose of the population and conduct further observation of the radiation situation. Measures intended to reduce irradiation doses includes: provision of population with less radioactive water sources, the regulation of medical radiation procedures (mostly - X-ray diagnostic procedures), the rational use of fertilizers with 40K content, construction of buildings on the territories with the lowest values of gamma radiation and radon release from soil, use of materials with low content of natural radionuclides for building construction, provision of premises with effective ventilation and radiation monitoring of buildings at any stages of construction, reconstruction or repair.

Dialysate potassium and risk of death in chronic hemodialysis patients

BACKGROUND

Few data guide the prescription of dialysate potassium (dK) in hemodialysis, which is usually prescribed empirically on the basis of predialysis serum potassium levels.

METHODS

This was a retrospective cohort study of prospectively collected data. We studied all patients initiating chronic hemodialysis in the Northern Alberta Renal Program (NARP) between January 2001 and December 2006. Data on demographic, clinical and treatment characteristics as well as the dates of death or transplant were extracted from the NARP database. We aimed to examine the relation between dialysate potassium level and all-cause death.

RESULTS

During the study, 515/1,267 of patients (41%) died. The frequency of dK of 0 or 1 mEq/L, 2, 3 and 4 mEq/L was 6%, 40%, 51% and 3%, respectively. In our base model, which considered dK as a categorical exposure, the hazard ratios associated with 0 or 1 mEq/L, 2, 3 and 4 mEq/L were 1.13 (95% confidence interval [95% CI], 0.78-1.63), 1 (referent), 1.29 (95% CI, 1.07-1.56) and 1.74 (95% CI, 1.09-2.77), respectively. When markers of inflammation or malnutrition were adjusted for separately, the association between dK and mortality was attenuated but remained significant. After simultaneous adjustment for markers of inflammation and malnutrition, the risk of death associated with the higher dK categories was attenuated, and the overall trend was eliminated. Analyses using dK as a time-varying covariate found similar results.

CONCLUSIONS

Although unadjusted and partially adjusted models suggested a graded association between higher dK and the risk of all-cause death, this association was apparently due to confounding by factors suggesting malnutrition and inflammation. The relative paucity of data on the association between dK and clinical outcomes despite the biological importance of potassium suggest that further studies are needed.

[Alcoholism and possible consequences for the central nerval system - pontine and extrapontine myelinolysis]

The central pontine and extrapontine myelinolysis is an important entity in the neurology disorders in the context with alcohol abuse. Though often first based on clinical characteristics, the diagnosis can be often supported with radiologic imaging.

Survival of extreme hyperkalemia

Severe hyperkalemia has been reported to lead to typical ECG changes, often reflecting cardiac abnormalities which finally lead to death in arrhythmias. The present report describes a 77-year-old male, who developed extreme hyperkalemia because of treatment with a potassium saving diuretic in combination with potassium supplementation and subsequent development of urinary retention. In spite of a maximal potassium value of 10.1 mmol/l only non-specific ECG-changes were found. The patient survived after an uneventful dialysis. Thus, extreme hyperkalemia may occur without typical ECG changes and serum potassium values exceeding 10 mmol/l may be survived.

Glucose-insulin-potassium therapy in patients with ST-segment elevation myocardial infarction

CONTEXT

The clinical benefit of glucose-insulin-potassium (GIK) infusion in patients with ST-segment elevation myocardial infarction (STEMI) is unclear. While some smaller trials suggest benefit, in the CREATE-ECLA trial, GIK infusion had no effect on 30-day mortality in 20,201 patients.

OBJECTIVES

To determine the association between GIK infusion therapy and 30-day and 6-month outcomes in patients with STEMI.

DESIGN, SETTING, AND PARTICIPANTS

Primary analysis of the OASIS-6 GIK randomized controlled trial of 2748 patients with acute STEMI; prespecified analyses of the combined trial data from the OASIS-6 GIK and CREATE-ECLA GIK trial populations of 22,943 patients with acute STEMI; subgroup analysis on the timing of initiation of GIK infusion therapy and outcomes; and post hoc analyses exploring whether GIK infusion may cause early harm by increasing glucose and potassium levels and net fluid gain.

INTERVENTION

High-dose GIK solution consisting of 25% glucose, 50 U/L of regular insulin, and 80 mEq/L of potassium infused at 1.5 mL/kg per hour for 24 hours.

MAIN OUTCOME MEASURES

Mortality rates at 30 days and 6 months in the OASIS-6 GIK trial and rates of death, heart failure, and the composite of death or heart failure at 3 and 30 days in the combined OASIS-6 GIK and CREATE-ECLA GIK trial populations.

RESULTS

At 6 months, 148 (10.8%) GIK infusion patients and 143 (10.4%) control patients died in the OASIS-6 trial (hazard ratio [HR], 1.04; 95% CI, 0.83-1.31; P = .72); 153 (11.1%) GIK patients and 185 (13.5%) control patients had heart failure (HR, 0.83; 95% CI, 0.67-1.02; P = .08); and 240 (17.5%) GIK patients and 264 (19.2%) control patients had a composite of death or heart failure (HR, 0.91; 95% CI, 0.76-1.08; P = .27). In the prespecified analyses of the combined trial data, there were 712 deaths (6.2%) in the GIK group and 632 deaths (5.5%) in the control group at 3 days (HR, 1.13; 95% CI, 1.02-1.26; P = .03). This difference disappeared by 30 days, with 1108 deaths (9.7%) in the GIK group and 1068 (9.3%) in the control group (HR, 1.04; 95% CI, 0.96-1.13; P = .33). GIK therapy increased levels of glucose, potassium, and net fluid gain postinfusion, all 3 of which predicted death after adjusting for multiple confounders. Adjusting for glucose, potassium, and net fluid gain eliminated the apparent increase in mortality at 3 days observed with GIK infusion, suggesting a direct association with these factors. Administration of GIK infusion within 4 hours of symptom onset yielded no benefit compared with later initiation.

CONCLUSIONS

Infusion of GIK provided no benefit and may cause early harm following STEMI. Avoidance of infusion-related hyperglycemia, hyperkalemia, and net fluid gain may be advisable in future studies of metabolic modulation in patients with STEMI.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00064428.

Treatment of hypertension with nutraceuticals, vitamins, antioxidants and minerals

Hypertension is the most common reason for visits to physicians' offices and the primary reason for prescription drug use. The target organ damage associated with hypertension, such as stroke, myocardial infarction, congestive heart failure, renal disease and large artery disease, can be mitigated by aggressive nondrug and drug therapies. Hypertension is a syndrome of various metabolic, functional and structural abnormalities that must be viewed in a more global setting of cardiovascular risk. Aggressive detection, evaluation and treatment of the 'blood vessel health' is mandatory to modern hypertensive care. Lifestyle modifications in conjunction with vitamins, minerals, antioxidants, nutraceutical supplements, optimal nutrition and drug therapy will prevent and treat hypertension and its sequelae while addressing global cardiovascular risk, vascular biology, endothelial dysfunction and overall vascular health.

The role of the BK channel in potassium homeostasis and flow-induced renal potassium excretion

The kidney is the major regulator of potassium homeostasis. In addition to the ROMK channels, large conductance Ca(2+)-activated K(+) (BK) channels are expressed in the apical membrane of the aldosterone sensitive distal nephron where they could contribute to renal K(+) secretion. We studied flow-induced K(+) secretion in BK channel alpha-subunit knockout (BK(-/-)) mice by acute pharmacologic blockade of vasopressin V(2) receptors, which caused similar diuresis in wild-type and knockout mice. However, wild-type mice, unlike the BK(-/-), had a concomitant increase in urinary K(+) excretion and a significant correlation between urinary flow rate and K(+) excretion. Both genotypes excreted similar urinary amounts of K(+) irrespective of K(+) diet. This was associated, however, with higher plasma aldosterone and stronger expression of ROMK in the apical membrane of the aldosterone-sensitive portions of the distal nephron in the knockout than in the wild-type under control diet and even more so with the high-K(+) diet. High-K(+) intake significantly increased the renal expression of the BK channel in the wild-type mouse. Finally, despite the higher plasma K(+) and aldosterone levels, BK(-/-) mice restrict urinary K(+) excretion when placed on a low-K(+) diet to the same extent as the wild-type. These studies suggest a role of the BK channel alpha-subunit in flow-induced K(+) secretion and in K(+) homeostasis. Higher aldosterone and an upregulation of ROMK may compensate for the absence of functional BK channels.

The Role of the Urinary Epithelium in the Pathogenesis of Interstitial Cystitis/Prostatitis/Urethritis

The urothelium plays a pivotal role as a barrier between urine and its solutes and the underlying bladder. Bladder surface mucus is a critical component of this function. The biologic activity of mucus that imparts this barrier function is generated by the highly anionic polysaccharide components (eg, glycosaminoglycans), which are extremely hydrophilic and trap water at the outer layer of the umbrella cell. This trapped water forms a barrier at the critical interface between urine and the bladder. The result is a highly impermeable urothelium that serves as a key protective barrier for the bladder interstitium. In interstitial cystitis (IC), disruption of the urothelial barrier may initiate a cascade of events in the bladder, leading to symptoms and disease. Specifically, epithelial dysfunction leads to the migration of urinary solutes, in particular, potassium, that depolarize nerves and muscles and cause tissue injury. Exogenous heparinoids can restore the barrier function of the urothelium and thus successfully treat patients with IC. Groups of patients who have been given a diagnosis of IC, chronic prostatitis, and urethritis have been shown to have IC by virtue of their shared potassium sensitivity. It would seem, therefore, that mucous deficiency may be present throughout the lower urinary tract. If one is to rename these diseases, perhaps it is best to do so in reference to a shared loss of epithelial barrier function. A name such as lower urinary dysfunctional epithelium would incorporate all of these diseases under a single pathophysiologic process. As a result of these discoveries, a new paradigm for diagnosis and treatment is emerging.

Neural Upregulation in Interstitial Cystitis

Interstitial cystitis (IC) is a syndrome of bladder hypersensitivity with symptoms of urgency, frequency, and chronic pelvic pain. Although no consensus has been reached on the underlying cause of IC, several pathophysiologic mechanisms, including epithelial dysfunction, mast cell activation, and neurogenic inflammation, have been proposed. Despite multiple different causes of urinary cystitis, the bladder's response to cystitis is limited and typical. Animal experiments have shown upregulation of proteinase-activated receptors, tryptase, beta-nerve growth factor, inducible nitric oxide synthase, nuclear transcription factor-kappaB, c-Fos, phosphodiesterase 1C, cyclic adenosine monophosphate (cAMP)-dependent protein kinase, and proenkephalin B. After the noxious stimulus has abated, downregulation of genes appears to follow. Distention of the bladder results in the release of adenosine triphosphate (ATP) from urothelial cells, which activates purinergic P2X3 receptors. Activation by ATP of P2X3-expressing afferents is a fundamental signaling factor in bladder sensation and appears to play a role in bladder reflexes. Fos proteins present in spinal cord neurons have been shown to be upregulated in animals that have undergone cyclophosphamide-induced chemical cystitis. These and other findings suggest that neural upregulation occurs both peripherally and centrally in subjects with chronic cystitis. It is unclear whether neural mechanisms and inflammation are the cause of IC or the result of other initiating events. Neural upregulation is known to play a role in the chronicity of pain, urgency, and frequency and represents an exciting area of research that may lead to additional treatments and a better understanding of IC.

Potassium and phosphorus repletion in hospitalized patients: implications for clinical practice and the potential use of healthcare information technology to improve prescribing and patient safety

OBJECTIVES

Evaluate potassium and phosphorus repletion in hospitalized patients. Assess the potential role for use of various methods, including healthcare information technology, to improve prescribing and patient safety.

RESEARCH DESIGN AND METHODS

Inpatient medication profiles were screened to identify orders for potassium and phosphorus replacement products. Electronic laboratory and medical records were used to evaluate efficacy and safety. Eligibility for oral therapy was defined by the presence of other scheduled oral medications on the medication profile. Appropriateness of prescribing was based on adherence to the hospital guidelines for repletion.

RESULTS

Overall, 134 orders for potassium in 92 patients and 36 orders for phosphorus in 27 patients were evaluated over a 3-week data collection period. Intravenous (IV) potassium was prescribed in 73% of replacement episodes (46% as single doses and 54% within large volume IV fluids), with 85% for normokalemia or mild-to-moderate cases of hypokalemia. Phosphorus orders involved single doses of IV potassium phosphate (mean 13.1 mmol) in 75% of cases. Approximately 85% of doses were for mild or moderate hypophosphatemia. Eligibility for oral therapy was evident in 74% of normokalemic or mild hypokalemic cases receiving IV potassium products and in 33% of cases receiving IV phosphorus replacement. Six cases of mild hyperkalemia were observed. No hyperphosphatemia was documented. Study limitations include use of a retrospective design, inability to discern whether some electrolyte doses were given with a preventative intent, potential overestimation of the number of patients eligible for oral repletion, and lack of data on the accessibility of the laboratory serum concentrations or the awareness of serum values to the prescribers.

CONCLUSIONS

Intravenous potassium and phosphate products are commonly prescribed for mild or moderate cases of hypokalemia or hypophosphatemia. Many patients met eligibility for oral therapy. Efforts to enhance prescriber education and implement computerized prescribing and decision support systems have the potential to improve prescribing and reduce possibilities of adverse drug events and medication errors related to potassium and phosphate administration.

[A girl with hereditary myotonia due to an exceptional sodium channel mutation]

A 22-month-old girl had cramps and stiffness of her muscles. After medical history, physical examination and an EMG, a short differential diagnosis based on the symptoms of myotonia was made. Initially, the symptoms were incorrectly assumed to be due to Becker's myotonia, an autosomal recessive condition caused by a mutation in the chloride channel. Molecular analysis did not show a defect in the chloride channel, but instead a defect in the sodium channel of the muscle fibre. Since defects in the sodium channel are responsible for several myotonic diseases, further analysis was necessary. Based on knowledge of the structure and mechanism of the sodium channel and study of literature on cases involving the identical mutation, the diagnosis 'potassium-aggravated myotonia' (PAM) was made. Re-evaluation of the patient showed that her symptoms fitted the diagnosis 'myotonia permanens', the severest form of PAM. She was treated with mexiletine. In myotonia several features can give direction to the diagnosis, including sensitivity to temperature and exercise, and family history. However, it is often necessary to use molecular analysis to be able to diagnose the disease correctly, make a prognosis and predict the risk of recurrence as well as to formulate a treatment plan.

Anti-inflammatory effects of insulin and pro-inflammatory effects of glucose: relevance to the management of acute myocardial infarction and other acute coronary syndromes

Hyperglycemia worsens morbidity and mortality for patients in intensive care or with acute myocardial infarction, stroke, or coronary artery bypass grafts. The control of hyperglycemia with insulin improves clinical outcomes for patients with these conditions. This article reviews the anti-inflammatory effects of insulin and pro-inflammatory effects of glucose and free fatty acids, and provides a mechanistic justification for maintaining euglycemia with insulin infusions. Hyperglycemia induced by infusions of a fixed dose of insulin with high rates of glucose may neutralize the benefit of insulin, and such regimens should be replaced by infusion of insulin to restore and maintain euglycemia.

Mechanism by which hyperglycemia plays a role in the setting of acute cardiovascular illness

Acute hyperglycemia is associated with excess morbidity and mortality in acute cardiovascular illness in both diabetic and nondiabetic patients. Hyperglycemia is associated with altered myocardial energetics, but abnormalities in glucose oxidation and glycolysis do not fully account for this excess risk. Hyperglycemia leads to a pro-oxidative/proinflammatory state that is associated with endothelial dysfunction, diminished coronary vasodilatory reserve, and a prothrombotic state. Hyperglycemia negates the protective effect of ischemic preconditioning and, most importantly, appears to interfere with the salutary effects of insulin in acute cardiovascular illness. Aggressive therapy with continuous infusion of insulin seems to improve a host of metabolic and physiologic effects associated with acute hyperglycemia and appears warranted if euglycemia can be maintained.

Glucose, insulin, and potassium for metabolic support in acute myocardial infarction: is the jury still out?

During ischemic and cardiomyopathic conditions, carbohydrate (glucose) metabolism in cardiomyocytes predominates over use of free fatty acids. The shift to glucose metabolism is a physiologic response to ischemia, which in many patients, particularly diabetics or those who are insulin-resistant, is blunted. Free fatty acid metabolism during ischemia produces higher levels of lactate and hydrogen ions within the ischemic cells. This in turn degrades myocardial contractility, induces diastolic dysfunction, and reduces the arrhythmogenic threshold of the cardiomyocyte. Suppression of free fatty acid uptake and oxidation by any means will increase myocardial glucose substrate utilization in ischemia. Theoretically, then, an insulin-glucose solution that can augment GLUT-1 and GLUT-4 translocation to the sarcolemmal membrane can assist cardiomyocyte survival during ischemia; however, study results have not supported metabolic therapy. It is essential for any investigation of glucose, insulin, potassium therapy to separate out the effect of hyperglycemia and glucose toxicity to make any meaningful comment on the effectiveness of metabolic support in myocardial infarction.

Properties of BK(Ca) channels in oral keratinocytes

Keratinocytes are important for epithelial antimicrobial barrier function. The activity of ion channels can affect the proliferation of keratinocytes. Little is known about Ca2+-activated K+ currents in these cells. Ion currents in normal human oral keratinocytes were characterized with a patch-clamp technique. In whole-cell configuration, depolarizing pulses evoked K+ outward currents (I(K)) in oral keratinocytes. Iberiotoxin (200 nM) and paxilline (1 microM) suppressed I(K); however, neither apamin (200 nM) nor 5-hydroxydecanoate (30 microM) had any effects on it. Caffeic acid phenethyl ester, a compound of honeybee propolis, increased I(K) with an EC50 value of 12.8 +/- 1.2 microM. In inside-out patches, a BK(Ca) channel was observed in keratinocytes, but not in oral squamous carcinoma (OCE-M1) cells. Caffeic acid phenethyl ester or cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate applied to the intracellular surface of a detached patch increased BK(Ca)-channel activity. The results demonstrate that the properties of BK(Ca) channels in normal human oral keratinocytes are similar to those described in other types of cells. Caffeic acid derivatives can also stimulate BK(Ca)-channel activity directly.

High-dose glucose-insulin-potassium treatment reduces myocardial apoptosis in patients with acute myocardial infarction

BACKGROUND

Several clinical trials have suggested that a metabolic cocktail of glucose-insulin-potassium (GIK) decreases mortality rates in patients with acute myocardial infarction (AMI). It has also been reported that Fas-mediated apoptosis plays an important role in ischaemic/reperfusion injury in the rat model. This study was designed to evaluate the interaction of ischaemic/reperfusion and reperfusion therapy coadministered with high-dose GIK treatment on soluble Fas/APO-1 (sFas) and Fas ligand (sFasL) plasma concentration in patients with AMI.

MATERIALS AND METHODS

Seventy-four patients presenting with AMI who underwent reperfusion therapy were randomized into a GIK group (n = 35) receiving high-dose GIK for 24 h or a vehicle group (n = 39). Thirty-four control subjects were also enrolled in the present study. Strepavidin-biotin ELISA was used to determine the soluble sFas and sFasL plasma concentration at baseline, 24 h (h), 3 day (d), 7 d and 14 d.

RESULTS

Soluble Fas and sFas-L serum concentrations ([sFas] and [sFas-L]) of patients with AMI were significantly elevated at baseline as compared with normal controls (NCs; P < 0.01 vs. NC). The sFas in the GIK and vehicle groups markedly decreased 24 h after the GIK infusion (10.7-->5.9 ng mL(-1) and 9.7-->6.5 ng mL(-1); P < 0.01 vs. baseline) and then increased during the 3-7-d period (5.9-->12.1 ng mL(-1) and 6.5-->11.1 ng mL(-1); P < 0.01 vs. 24 h). The GIK group demonstrated reduced sFas (12.1-->5.9 ng mL(-1)) at 14 d (P < 0.01 vs. 7 d), with no concomitant changes in the vehicle group. The sFas-L in the GIK and vehicle groups was not significant different during the 14-d period.

CONCLUSIONS

These results indicate that the sFas and sFasL in patients with AMI increased significantly compared with NC. Owing to the cardioprotective effects reported here and by others, a high-dose GIK infusion co-administered with the timely re-establishment of nutritive perfusion should be strongly considered as a treatment of choice for AMI. Additionally, sFas may be a valuable marker of the physiological response to ischaemic/reperfusion injury and reperfusion associated with high-dose GIK treatment.

The in vitro quality of washed, prestorage leucocyte-depleted red blood cell concentrates

BACKGROUND AND OBJECTIVES

No data are currently available on the quality of washed prestorage leucocyte-depleted red blood cell concentrates (RCCs).

MATERIALS AND METHODS

Five groups of RCCs stored in additive solution (SAG-M) were washed. The groups differed in the age of RCCs (2-5 days or 11-15 days), the temperature during the washing procedure and a 6-h storage period (4 degrees C or room temperature) and the washing solution (saline, SAG-M or 5% albumin). We measured ATP, 2,3-diphosphoglycerate (2,3-DPG), haemolysis, blood cell count, Na(+), K(+), pH, pO(2), pCO(2) and lactate, before and after the washing procedure and hourly during the 6-h postwash storage period.

RESULTS

The erythrocyte ATP content increased by 2-13%, relative to the baseline value, during the washing procedure. The 2,3-DPG level decreased by 15-35% in 2-6-day-old RCCs and by 30-40% in 11-15-day-old RCCs (relative to baseline values) during the washing procedure. In RCCs that were washed and stored at room temperature, and in 2-week-old RCCs, a further decrease in 2,3-DPG of up to 40%, relative to the baseline value, was observed during the 6-h postwash time-period.

CONCLUSIONS

Washing of RCCs stored in SAG-M results in a considerable, significant loss of erythrocyte 2,3-DPG, especially in older RCCs. This loss increases in during a 6-h storage period postwash, even at 4 degrees C. This loss of erythrocyte quality might well outweigh the benefits of washed SAG-M RCCs during massive transfusion in neonates.

Optimal composition of the dialysate, with emphasis on its influence on blood pressure

Introduction. From the beginning of the dialysis era, the most appropriate composition of the dialysate has been one of the central topics in the delivery of dialysis treatment.

METHODS

A discussion is employed to achieve a consensus on key points relating to the composition of the dialysate, focusing on the relationships with blood pressure behaviour.

RESULTS

Sodium balance is the cornerstone of intra-dialysis cardiovascular stability and good inter-dialysis blood pressure control. Hypernatric dialysis carries the risk of positive sodium balance, with the consequent possibility of the worsening sense of thirst and hypertension. Conversely, hyponatric dialysis may lead to negative sodium balance, with the possibility of intra-dialysis cardiovascular instability and 'disequilibrium' symptoms including fatigue, muscle cramps and headache. The goal is to remove with dialysis the exact amount of sodium that has accumulated in the inter-dialysis interval. The conductivity kinetic model is applicable on-line at each dialysis session and has been proved to be able to improve intra-dialytic cardiovascular stability in hypotension-prone patients. Therefore, it should be regarded as a promising tool to be implemented in everyday clinical practice. Serum potassium concentration and variations during dialysis treatment certainly play a role in the genesis of cardiac arrhythmia. Potassium profiling, with a constant gradient between plasma and dialysate, should be implemented in clinical practice to minimize the arrhythmogenic potential of dialysis. Calcium plays a role both in myocardial contractility and in peripheral vascular resistance. Therefore, an increase in dialysate calcium concentration may be useful in cardiac compromised hypotension-prone patients. Acid-buffering by means of base supplementation is one of the major roles of dialysis. Bicarbonate concentration in the dialysate should be personalized in order to reach a midweek pre-dialysis serum bicarbonate concentration of 22 mmol/l. The role of convective dialysis techniques in cardiovascular stability is still under debate. It has been demonstrated that dialysate temperature and sodium balance play a role and this should be taken into account. Whether removal of vasoactive, middle-sized compounds by convection plays an independent role in improving cardiovascular stability is still uncertain.

CONCLUSIONS

The prescription of dialysis fluid is moving from a pre-fixed, standard dialysate solution to individualization of electrolyte and buffer composition, not only during the dialysis session, but also within the same session (profiling) in order to provide patients with an optimal blood purification coupled with a high degree of tolerability.

Glucose-insulin-potassium infusion as adjunctive therapy in myocardial infarction: current evidence and potential mechanisms

BACKGROUND

In ST-elevation myocardial infarction (STEMI) there is conflicting evidence that mortality, morbidity and infarct size is reduced by therapies influencing myocardial metabolism, such as infusion of glucose-insulin-potassium (GIK). Several clinical trials with GIK have already provided insight into the magnitude of this effect. The aim of this article was to review randomized trials on adjunctive GIK infusion in STEMI.

METHODS

Randomized trials comparing GIK with placebo or untreated controls in patients with STEMI were identified by electronic and manual searches. A systematic analysis of all data was performed, with regard to inclusion criteria, dose of GIK and additional use of reperfusion therapy. Thirteen trials, involving 4992 patients, were included.

RESULTS

Overall, hospital mortality was 10.8% after GIK compared to 12.9% in controls (p = 0.02). GIK infusions were in particular effective when a high dose was used and if given as an adjunct to reperfusion therapy. In patients with heart failure on admission, GIK may have worse effects. In all analyzed trials, GIK infusion caused only mild adverse effects, although fluid overload may be a problem in certain patients.

CONCLUSIONS

GIK may reduce mortality in patients with STEMI, particularly if a high dose is used and when GIK is administered as an adjunct to reperfusion therapy. However, all studies had a relative small sample size and additional large randomized trials are certainly needed before a definite conclusion can be made. The limited evidence currently available does not warrant GIK therapy to be applied in patients at the present time.

Reversal of Glucose-Insulin-Potassium-Induced Hyperglycemia by Aggressive Insulin Treatment in Postoperative Heart Failure

Metabolic support with glucose-insulin-potassium (GIK) significantly reduces the morbidity and mortality of patients in cardiogenic shock after hypothermic ischemic arrest for aortocoronary bypass surgery. However, a small subset of these patients develops postoperative insulin resistance regardless of their preoperative diabetic status. Whether GIK directly contributes to higher mortality in these patients is unknown. We reviewed the records of 322 patients whose treatment for postoperative cardiogenic shock included GIK. Ten patients (3%) had postoperative hyperglycemia (serum glucose > or =250 mg/dl or 13.9 mmol/l) due to insulin resistance. These were compared to randomly selected GIK-treated, insulin-responsive patients (n = 10) and non-GIK-treated patients (n = 10) for comparison. The insulin-resistant patients required increasing amounts of regular insulin up to 130 U/h until blood glucose levels fell below 250 mg/dl. However, short-term outcomes (IABP support time, length of stay in ICU, 7-day mortality) for insulin- resistant patients were indistinguishable from those for insulin-responsive patients. These data indicate that postoperative iatrogenic hyperglycemia in patients after cardiopulmonary bypass may not be detrimental per se and is reversible when treated with supplemental insulin.

Drug labeling; orally ingested over-the-counter drug products containing calcium, magnesium, and potassium. Final rule

The Food and Drug Administration (FDA) is amending the general labeling provisions for over-the-counter (OTC) drug products to require that the labeling of all OTC drug products intended for oral ingestion include: The calcium content per dosage unit when the product contains 20 milligrams (mg) or more per single dose; a warning statement that persons with kidney stones and persons on a calcium-restricted diet should ask a doctor before using when the product contains more than 3.2 grams (g) of calcium in the labeled maximum daily dose; the magnesium content per dosage unit when the product contains 8 mg or more per single dose; a warning statement that persons with kidney disease and persons on a magnesium-restricted diet should ask a doctor before using if the product contains more than 600 mg magnesium in the labeled maximum daily dose; the potassium content per dosage unit when the product contains 5 mg or more per single dose; and a warning statement that persons with kidney disease and persons on a potassium restricted diet should ask a doctor before using if the product contains more than 975 mg potassium in the labeled maximum daily dose. FDA is issuing this final rule in order to provide uniform calcium, magnesium, and potassium content and warning labeling for all OTC drug products intended for oral ingestion whether marketed under an OTC drug monograph, the ongoing OTC drug review, a new drug application (NDA) or abbreviated new drug application (ANDA), or no application.

The pitfalls of potassium replacement in thyrotoxic periodic paralysis: a case report and review of the literature

Thyrotoxic Periodic Paralysis is an uncommon disorder seen primarily in Asian males and caused by excessive thyroid hormones. This is an endocrine emergency that can lead to respiratory failure, dysrhythmia, and death. The mainstay of therapy has been potassium replacement, however, recent evidence suggests propranolol is a more effective therapy. We present a severe case of TPP in a 22-year-old Latino male with rapidly progressive ascending paralysis and hypokalemia severe enough to lead to cardiac arrest.

[Influence of potassium on Mg- and Ca-metabolism in cows: effects and side effects of scientific research]

Results of scientific studies are obtained by analysing of the present knowledge of a current problem and a corresponding new experimental set-up. Under ideal conditions the data of the new study agree with the deduced working hypothesis. This general consideration is true for the well established correlation between K content and growth rates of plants. At low K concentrations (up to 3% of dry matter) K causes a linear increase of growth and finally a saturation. This positive effect of K on growth rates of plants is accompanied by some side effects. There is no doubt that a high intake of K is involved in the pathogenesis of grass tetany and of milk fever. The present publication gives some information about this correlation and discusses the discrepancy between the intention of a scientific study and possible "side effects", which cannot be predicted in many cases.

Evaluation of Salvaged Myocardium After Acute Myocardial Infarction Using Single Photon Emission Computed Tomography After 201Tl-Glucose-Insulin Infusion

BACKGROUND

GIK-201Tl imaging reportedly improves the detection of viable myocardium, so the present study evaluated whether it can detect myocardial viability after acute myocardial infarction (AMI).

METHODS AND RESULTS

Resting 201Tl and 99mTc-pyrophosphate (PYP) dual single photon emission computed tomography (SPECT) and 201Tl SPECT after 201Tl with GIK (10% glucose, insulin 5 U, and KCl 10 mmol) infusion (GIK-201Tl) were performed in 25 AMI patients within 10 days of admission. GIK-201Tl SPECT images were obtained immediately and 4 h after infusion. Left ventriculography (LVG) was performed within 3 weeks and at 6 months when follow-up 201Tl SPECT was also performed. From 20 SPECT segments, both the summed defect score (RDS) and the number of defect segments (ES) were calculated. The infarcted area was defined as 99mTc-PYP uptake segments. Wall motion was estimated in 7 LVG segments. The ES of R-201Tl (5.5 +/- 2.8), immediate GIK-201Tl (4.0 +/- 2.3), and 4-h GIK-201Tl (5.6 +/- 2.7) were lower than that of 99mTc-PYP (7.5 +/- 4.1) (p<0.05), and the ES had significantly declined 6 months later on 201Tl (3.5 +/- 2.8) (p<0.05). Although the RDS of R-201Tl (11.3 +/- 7.9) and 4-h GIK-201Tl (11.2 +/- 6.3) were greater than at the 6-month 201Tl (7.1 +/- 6.5), immediate GIK-201Tl (7.4 +/- 6.5) was equivalent to follow-up 201Tl. The sensitivity of immediate GIK-201Tl was highest among the imaging methods.

CONCLUSION

To detect myocardial viability after AMI, early imaging with GIK-201Tl is more useful than resting 201Tl imaging.

Acute coronary syndrome: potassium, magnesium and cardiac arrhythmia

BACKGROUND

Cardiac arrhythmia is often present in patients with acute coronary syndrome (ACS) and may be due to the electrolyte imbalance.

AIM

To assess the prevalence and clinical significance of electrolyte imbalance in ACS.

METHODS

Serum potassium and magnesium levels were measured within the first few hours in 204 consecutive patients with ACS admitted to our department over a period of 23 months. Cardiac arrhythmia was documented using continuous ECG monitoring, telemetry or standard ECG.

RESULTS

Hypokalemia was observed in 34% of patients, and was significantly associated with the occurrence of life-threatening ventricular arrhythmias (26% of patients with potassium level <4 mmol/l vs 11.9% of patients with normokalemia, p<0.001). No relationship was found between potassium level and supraventricular arrhythmias or in-hospital mortality. Decreased magnesium serum concentration was found in 22% of patients but was not significantly associated with cardiac arrhythmias or mortality.

CONCLUSIONS

Hypokalemia and hypomagnesemia are often present in patients with ACS. The former is associated with dangerous ventricular arrhythmias. Early assessment of electrolyte serum concentration is needed in order to implement proper supplementation.

Effects of calcium and magnesium pretreatment on hyperkalaemic cardiac arrest in rats

BACKGROUND AND OBJECTIVE

Administration of calcium safely and effectively reverses many of the electrophysiological actions of hyperkalaemia, but it has not been studied for pretreatment. Based on cellular studies, magnesium also has been suggested to prevent the effects of potassium on the heart. As their mechanisms of action differ, a combination of these drugs might have a synergistic protective action. Both compounds are inexpensive and can be administered safely in modest doses. We investigated whether magnesium, calcium or their combination could protect against hyperkalaemic cardiac arrest.

METHODS

Twenty-four adult rats were anaesthetized with halothane and randomly pretreated with CaCl2 15 mg kg(-1), MgSO4 30 mg kg(-1), CaCl2 7.5 mg kg(-1) + MgSO4 15 mg kg(-1) or physiological saline. Potassium (0.01 mmol kg(-1) h(-1)) was infused. The times to the first dysrhythmia, mean arterial pressure decrease to <40% of baseline and cardiovascular collapse were measured.

RESULTS

Serum potassium concentrations increased to similar values in all groups (to 12.0 +/- 0.2 mmol L(-1) at the time of collapse). No differences in survival times were observed between groups. There was a trend for respiratory values to be better in the group receiving magnesium.

CONCLUSIONS

Pretreatment with magnesium, calcium or a combination of both did not influence the time to cardiovascular collapse, and is therefore--at least in our model--not of any benefit in preventing hyperkalaemic cardiac arrest.

High-dose glucose-insulin-potassium after cardiac surgery: a retrospective analysis of clinical safety issues

BACKGROUND

Metabolic treatment with insulin or glucose-insulin-potassium (GIK) has received attention in association with myocardial infarction, cardiac surgery and critical care. As a result of insulin resistance during neuroendocrine stress, doses of insulin up to 1 IU kg-1 b.w.*h are required to achieve maximal metabolic effects after cardiac surgery. The clinical experience with regard to safety issues of such a high-dose GIK regime in critically ill patients after cardiac surgery is reported.

METHODS

Retrospective, observational study involving all patients treated with high-dose GIK after cardiac surgery during one year in a cardiovascular center at a University Hospital.

RESULTS

Eighty-nine patients out of 854 adult patients undergoing cardiac surgery were treated with high-dose GIK. Mean age was 69 +/- 1 years, Higgins score 5.3 +/- 0.3. Preoperatively 31.4% had left ventricular function EF< or =0.35 and 32.5% had sustained a myocardial infarct during surgery. Mortality was 5.6% and the average ICU stay was 3.7 +/- 0.5 days. The main indication for GIK was intraoperative heart failure (69.7%). The average glucose infusion rate during the first 6 h was 4.22 +/- 0.15 and 4.91 +/- 0.14 mg kg-1 b.w.*min, respectively, in diabetic and non-diabetic patients (P = 0.023). Blood glucose and s-potassium control was acceptable.

CONCLUSIONS

The high-dose GIK regime allowed substantial amounts of glucose to be infused both in diabetic and critically ill patients with maintenance of acceptable blood glucose control. Provided careful monitoring, this regime can be safely used in clinical practice and deserves further evaluation for treatment of critically ill patients following cardiac surgery.

Prospective study of potassium-associated acute transfusion events in pediatric intensive care

OBJECTIVE

Transfusion of packed red blood cells containing high concentrations of potassium have been associated with fetal and neonatal arrhythmia and hyperkalemic cardiac arrest. This study sought to determine the biochemical and associated clinical effects of packed red blood cells transfusion in critically ill children.

DESIGN

Prospective case series.

SETTING

Tertiary multidisciplinary university hospital pediatric intensive care unit.

PATIENTS

Consecutive sample of 28 children 2.7-27 kg (1 wk to 12 yrs old) receiving a packed red blood cell transfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Potassium concentration was prospectively measured from packed red blood cell transfusions. Adverse events were recorded during and for 4 hrs following transfusion including hyperkalemia, therapy for hyperkalemia, arrhythmia, cardiac arrest, and death. There were 54 packed red blood cell transfusions (mean volume of 11.8 +/- 2.8 mL/kg). The measured packed red blood cell potassium concentration was > 25 mmol/L in 16, 15-25 mmol/L in 11, and < 15 mmol/L in 25. The mean patient potassium concentrations before (3.85 +/- 0.55, range 2.7-5.2 mmol/L) and after transfusion (3.94 +/- 0.62, range 2.8-5.7 mmol/L) were not significantly different. There was no therapy required for hyperkalemia, no new arrhythmia, no cardiopulmonary arrest, and no deaths during and up to 4 hrs following transfusion. Of the six children given a bolus of packed red blood cells (> or = 5 mL/kg over < 10 mins), the maximum increase in patient potassium concentration was 0.8 mmol/L, in a child who had an initial potassium concentration of 2.7 mmol/L. No patient's potassium concentration was > 5 mmol/L following rapid transfusion.

CONCLUSIONS

This prospective study found no significant change in patient potassium concentration and no acute adverse events related to transfusion in critically ill children, including those receiving packed red blood cells by bolus. Larger prospective studies are required to evaluate the acute effects of rapid and central venous transfusion in critically ill children.