Blood Potassium Concentrations Research Articles

Accurate correction model of blood potassium concentration in hemolytic specimens

Accurate correction model of blood potassium concentration in hemolytic specimens

Haematological and Plasma Biochemical Parameters in Response to Natural Coccidian Infection in Barbari and Jamunapari Goat Breeds in Semi-arid Tropics

Background: Small ruminants like goats are considered the most resourceful and efficient animal all over the world. Eimeria species causes disease in goats associated with poor growth, diarrhoea and decrease in production, high morbidity and mortalities. The present study was conducted to analyse the haematological and biochemical parameters in response to natural coccidian infection in Barbari and Jamunapari goat breeds in semi-arid tropics. Methods: A total of 474 goats were examined; 96 goats were selected (48 Barbari and 48 Jamunapari) and divided on the basis of high (12 males and 12 females) and low (12 males and 12 females) oocyst per gram (OPG) counts of both Barbari and Jamunapari goats. The blood was aseptically collected from the jugular vein, using a 22-gauge needle for each animal separately in 5 ml blood for the haematological and biochemical estimations. Result: In haematological parameters of Barbari goats there were no significant (P greater than 0.05) differences in males and females. Although significantly higher values of RBC were observed in low OPG females, similar results were also observed in Hct, Mcv, Hb, MCH and MCHC. Whereas, in WBC, Lymphocyte, Monocyte and Granulocyte statistically had no significant (P greater than 0.05) differences among all the groups. In haematological parameters of Jamunapari goats no significant (P greater than 0.05) differences was seen in males and females of both the groups. The same group of Barbari goats were also selected for biochemical parameters and high OPG females had significantly (P less than 0.05) higher blood glucose values. The blood potassium concentration was found to be significantly (P less than 0.05) higher in low OPG males compared to high OPG males. The same group of Jamunapari goats were selected for biochemical parameters and ALT, total protein and globulin had significantly (P less than 0.05) higher values in high OPG females than others. A/G ratio had significantly (P less than 0.05) higher value observed in high OPG males.

Development of a diagnostic model for pre-washout screening of primary aldosteronism.

Primary aldosteronism (PA) diagnosis is affected by antihypertensive drugs that are commonly taken by patients with suspected PA. In this study, we developed and validated a diagnostic model for screening PA without drug washout. We retrospectively analyzed 1095 patients diagnosed with PA or essential hypertension. Patients were randomly grouped into training and validation sets at a 7:3 ratio. Baseline characteristics, plasma aldosterone concentration (PAC), and direct renin concentration (DRC) before and after drug washout were separately recorded, and the aldosterone-to-renin ratio (ARR) was calculated. PAC and ARR were higher and direct renin concentration was lower in patients with PA than in patients with essential hypertension. Furthermore, the differences in blood potassium and sodium concentrations and hypertension grades between the two groups were significant. Using the abbreviations potassium (P), ARR (A), PAC (P), sodium (S), and hypertension grade 3 (3), the model was named PAPS3. The PAPS3 model had a maximum score of 10, with the cutoff value assigned as 5.5; it showed high sensitivity and specificity for screening PA in patients who exhibit difficulty in tolerating drug washout. PA screening remains crucial, and standard guidelines should be followed for patients to tolerate washout. The PAPS3 model offers an alternative to minimize risks and enhance diagnostic efficiency in PA for those facing washout challenges. Despite its high accuracy, further validation of this model is warranted through large-scale clinical studies.

Factors in Predicting Short Term Mortality in ST Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Intervention

Background: Percutaneous coronary angiography and intervention have been applied in the diagnosis and treatment of coronary artery disease at Gia Dinh People's Hospital since April 2009 until now with very positive results, contributing to improving the quality of diagnosis and treatment. Treating cardiovascular patients with high technology. However, there is currently no research to help evaluate performance as well as prognostic factors affecting treatment outcomes at this unit. Therefore, we conducted this study with the research question: Short-term mortality rate in patients with ST-elevation acute myocardial infarction undergoing primary percutaneous coronary intervention at Gia Dinh People's Hospital. What is the year 2022 - 2023? What factors predict short-term mortality in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. Materials and methods: There were 163 patients at the Gia Dinh People's Hospital from November 2022 to September, 2023. This was a cohort study. Results: In-hospital and 30-day mortality rates after intervention were 4.29% and 4.91%, respectively. Short-term mortality prognostic factors include systolic blood pressure < 100 mmHg, arrhythmia at admission, TIMI score > 6, cardiogenic shock before the procedure, blood potassium concentration with mortality rate within 30 days after PCI, with p < 0.05. Conclusion: In clinical practice, attention should be paid to factors predicting 30-day mortality in STEMI patients include systolic blood pressure < 100 mmHg, arrhythmia at admission, TIMI score > 6, cardiogenic shock before the procedure, blood potassium concentration with mortality rate within 30 days after PCI.

Accurate correction model of blood potassium concentration in hemolytic specimens

Background and aimsThe results of blood potassium can be seriously affected by specimen hemolysis which may interfere with clinicians’ interpretation of test results. Redrawing blood and retesting may delay treatment time and it is not feasible for critically ill patients with difficulty in specimen collection. Therefore, it is significant to establish a mathematical model that can quickly correct the blood potassium concentration of hemolytic specimens. Materials and methodsThe residual blood samples from 107 patients at Peking University Third Hospital were collected to establish potassium correction model. Samples with different hemolysis indexes were obtained by ultrasonic crushing method. Blood potassium correction models of hemolysis specimens were established by linear regression and curve fitting using SPSS and MATLAB, respectively. In addition, blood samples from another 85 patients were used to verify the accuracy of the models and determine the optimal model. ResultsVariation of potassium (ΔK) was 0.003HI-0.03 (R2 = 0.9749) in linear regression model which had high correlation in ΔK and HI, and the correction formula was Kcorrection = Khemolysis-0.003 × HI + 0.03. Average rate of potassium change (αaverage) was 0.003 ± 0.0002 mmol/L in curve fitting model, and correction formula was Kcorrection = Khemolysis-0.003 × HI, and both men and women can use the same correction model. The accuracy of linear regression model was 96.5 %, and there was statistical difference between the verification results and the measured values (p < 0.05), while the accuracy of curve fitting model was 100 %, and there was no statistical difference between the verification results and the measured values (p = 0.552). The model was validated in an independent set of samples and all were within the TEa of 6 % and the accuracy of 100 %. ConclusionsBoth linear regression and curve fitting models of potassium correction had high accuracy, and can effectively correct the potassium concentration of hemolytic specimens, while the curve fitting model have superior accuracy.

Sociodemographic and clinical factors influencing serum potassium concentration: A retrospective cohort study

BackgroundSelf-care is crucial for maintaining the health and quality of life of individuals undergoing physical examinations, especially those with abnormal test results because they are at a higher risk of experiencing worse outcomes. However, there is currently a lack of comprehensive literature on the impact of sociodemographic and clinical factors on self-care practices related to serum potassium concentration among individuals undergoing physical examinations. Therefore, this study aimed to explore the sociodemographic and clinical factors influencing serum potassium concentration. MethodsData from 43,151 individuals who underwent physical examinations were retrospectively collected in January, April, July, and October of 2019–2021. The serum potassium concentrations of these individuals were compared based on sex, age, and residential area. Additionally, the whole cohort and a subset of 6698 individuals with available occupational information were included to analyze the sociodemographic factors associated with serum potassium concentration using logistic regression analysis. Furthermore, a propensity score matching approach was employed to match 642 individuals with abnormal serum potassium concentrations to 642 with normal serum potassium concentrations. Pearson’s correlation analysis was subsequently used to investigate the clinical factors contributing to abnormalities in serum potassium concentration. ResultsHigh temperatures; older age; male sex; living in the southern part of the city; and chemical, communication system, and transportation occupations were associated with a higher likelihood of experiencing abnormal serum potassium concentrations. Individuals with abnormal serum potassium concentrations had a higher prevalence of underlying diseases. Compared with the hypokalemia group, the hyperkalemia group exhibited a higher incidence of diabetes and cardiovascular disease. In the hyperkalemia group, serum potassium concentration positively correlated with serum creatinine concentration and negatively correlated with the estimated glomerular filtration rate (eGFR). In contrast, in the hypokalemia group, serum potassium concentration negatively correlated with creatinine concentrations, blood glucose concentration, and systolic and diastolic blood pressure, and positively correlated with eGFR. ConclusionsSociodemographic and clinical factors can affect blood potassium concentration. During daily self-care, it is essential for individuals with abnormal potassium concentrations to avoid exposure to relevant sociodemographic risk factors and seek medical attention as soon as possible to screen for diseases, such as hypertension, cardiovascular disease, and diabetes.

Heparin-induced hyperkalemia, can LMWH cause hyperkalemia? A systematic review.

Hyperkalemia, an elevated blood potassium concentration exceeding 5.0mEq/L, is associated with adverse outcomes and is frequently observed in hospitalized patients. Drug-induced hyperkalemia accounts for a significant proportion of cases, with heparin, commonly used for venous thrombosis prevention, suspected to contribute, though less recognized than other heparin-related side effects. Both unfractionated heparin (UFH) and low molecular weight heparin (LMWH) have been implicated in inducing hyperkalemia, primarily through the suppression of aldosterone levels and modulation of angiotensin II receptors. This systematic review examines the relationship between heparin, particularly LMWH, and hyperkalemia. Thirteen studies involving 1407 patients were analyzed. Findings indicated a lack of highquality evidence, with no significant increase in potassium levels associated with LMWH use. LMWH did not exhibit a dose-response relationship with hyperkalemia incidence. Additionally, mechanisms underlying the hypothetical LMWHinduced hyperkalemia remained inconclusive. While this suggests that LMWH is unlikely to be a primary cause of hyperkalemia, caution is warranted, especially in patients with elevated baseline potassium levels.

Supplementing urea molasses mineral block improves growth performances and blood biochemical parameters of Mithun calves (Bos frontalis)

This experiment aimed to determine the effect of urea molasses mineral block (UMMB) supplementation on growth performances and blood biochemical parameters of Mithun calves (Bos frontalis). Ten growing Mithun calves were allocated into two groups (control and UMMB) and the diet including natural grass (50%) and tree forage (50%) was used as basal diet. The Mithun calves from control group were fed only basal diet and calves from treatment group were fed basal diet with supplementation of UMMB. This experiment lasted for 12 weeks and nutrient intakes, digestibility, energy status, body weight gain and blood biochemical parameters were measured. The intakes, digestibilities and digestible intakes of dry matter, organic matter, crude protein, neutral detergent fibre and acid detergent fibre, energy intake, energy balance, mineral intake, total weight gain and average daily gain (ADG) were higher (p < 0.05) in UMMB supplemented group than in control group. The serum glucose, blood urea nitrogen (BUN), globulin, calcium, available phosphorus, sodium and potassium concentrations of UMMB supplemented group was also significantly higher (p < 0.05) than those of control group, however the albumin and chloride concentrations were not different (p > 0.05). Thus, UMMB supplementation increased the growth performances and some blood biochemical parameters of growing Mithun calves.

Uncovering the Neurobiological Consequences of High-Voltage Electrical Field Exposure on the Visual Working Memory of Macaques and Also Using Spiking Neural Network Model

High-voltage (HV) power transmission lines running near cities and villages can cause severe damage (Mental and physical). Due to the magnetic and electric fields they produce. This study aimed to investigate the effects of high-voltage (HV) electric fields on the spiking neural network model of the brain and biological and behavioral models of visual working memory. To achieve this goal, macaques were studied for their cognitive functions, expression of the NMDA receptor gene, MRI-assisted analysis of brain anatomy, and variations in blood sodium and potassium concentrations. The experimental group of macaques was exposed to a 3kV/m high-voltage field for four hours a day for one month. Computational models were then evaluated using experimental parameters. According to the results, it was observed that being exposed to high-voltage electric fields led to a reduction in the expression of the NMDA receptor gene, as well as a decrease in the levels of Sodium and potassium ions in the blood plasma. Additionally, analysis assisted by MRI showed a decrease in the volume of the hippocampus and amygdala after exposure to the electric field. In conclusion, the results of cognitive, genetic, blood, and MRI tests, along with the spiking neural network model, elucidate the mechanism of the visual working memory deterioration in macaques due to high-voltage electric field exposure.

Are slaughterhouse-obtained livers suitable for use in ex vivo perfusion research?

The success of the ex vivo machine perfusion of pig livers used for preclinical research depends on organ quality and availability. In this study, we investigated whether livers obtained from slaughterhouses are suitable and equivalent to livers obtained from laboratory pigs. Livers were obtained from slaughterhouse pigs stunned by electrocution or CO2 inhalation and from laboratory pigs. For the latter group, 45 minutes of warm ischemia was mimicked for a subgroup, ensuring a valid comparison with slaughterhouse-derived livers. Livers from CO2-stunned pigs showed lower indocyanine green clearance and bile production, higher blood lactate and potassium concentrations, and higher alanine aminotransferase activities than electrically stunned pigs. Furthermore, livers from electrically stunned pigs, and livers from laboratory pigs, subjected or not to warm ischemia, showed similar performance in terms of perfusion and metabolism. For an ex vivo liver model generated using slaughterhouse pigs, electrical stunning is preferable to CO2 stunning. Livers from electrically stunned slaughterhouse pigs performed similarly to laboratory pig livers. These findings support the use of livers from electrically stunned slaughterhouse pigs, which may therefore provide an alternative to livers obtained from laboratory pigs, consistent with the principle of the 3Rs.

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Hyperkalaemia can be an emergency presentation and refers to a blood potassium concentration of &gt;5.5 mmol/l. Olivia Walesby, an ECC resident at the University of Edinburgh, discusses the causes of hyperkalaemia, clinical presentation and acute treatment.

Post-exercise rehydration: Comparing the efficacy of three commercial oral rehydration solutions.

This study compared the efficacy of three commercial oral rehydration solutions (ORS) for restoring fluid and electrolyte balance, after exercise-induced dehydration. Healthy, active participants (N = 20; ♀ = 3; age ∼27 y, O2peak ∼52 ml/kg/min) completed three randomised, counterbalanced trials whereby intermittent exercise in the heat (∼36°C, ∼50% humidity) induced ∼2.5% dehydration. Subsequently, participants rehydrated (125% fluid loss in four equal aliquots at 0, 1, 2, 3 h) with a glucose-based (G-ORS), sugar-free (Z-ORS) or amino acid-based sugar-free (AA-ORS) ORS of varying electrolyte composition. Urine output was measured hourly and capillary blood samples collected pre-exercise, 0, 2 and 5 h post-exercise. Sodium, potassium, and chloride concentrations in urine, sweat, and blood were determined. Net fluid balance peaked at 4 h and was greater in AA-ORS (141 ± 155 ml) and G-ORS (101 ± 195 ml) than Z-ORS (-47 ± 208 ml; P ≤ 0.010). Only AA-ORS achieved positive sodium and chloride balance post-exercise, which were greater for AA-ORS than G-ORS and Z-ORS (P ≤ 0.006), as well as for G-ORS than Z-ORS (P ≤ 0.007) from 1 to 5 h. when provided in a volume equivalent to 125% of exercise-induced fluid loss, AA-ORS produced comparable/superior fluid balance and superior sodium/chloride balance responses to popular glucose-based and sugar-free ORS.

Arginine, symmetric and asymmetric dimethylarginine levels in canine leishmaniasis

The study aimed to investigate the levels of arginine, symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) in dogs with canine leishmaniasis (CanL) and their relationship with some renal and cardiovascular parameters. A total of 60 dogs were enrolled, including 40 with CanL and 20 healthy controls. The CanL group was divided into four stages based on clinical and laboratory findings. The levels of plasma arginine, SDMA, and ADMA were determined by high performance liquid chromatography (HPLC). The data from the healthy group were compared with those from the CanL group, and according to the stages. In dogs with CanL, systolic and diastolic blood pressure, plasma creatinine, cystatin-C, phosphorus, potassium, and low-density lipoprotein concentrations, the urine protein/creatinine ratio, the amount of nitric oxide, and creatine kinase-MB activity were higher, while the high-density lipoprotein concentration was lower compared to healthy controls. The concentration of arginine was low (p < 0.05) and the levels of ADMA (p < 0.001) and SDMA (p < 0.05) were high in dogs with CanL. There were no statistically significant differences in arginine concentration among the different stages of CanL. However, the concentration of plasma ADMA was higher in all stages of CanL compared to the healthy group, and the concentration of plasma SDMA was higher in Stage IV compared to the healthy group and Stage III. The present study demonstrates for the first time a decrease in arginine concentration and an increase in ADMA concentration in dogs with CanL. The increase in SDMA concentration in dogs with CanL was consistent with previous studies. However, compared to other renal parameters, SDMA exhibited limited performance distinguishing between clinical stages of CanL. These findings could be a source for future diagnostic and therapeutic studies to explain the renal and cardiovascular pathophysiology of CanL. Additional clinical studies that include treatment and patient follow-up with an assessment of the acute phase response are needed to provide a more detailed understanding of the changes observed in dogs with CanL.

Retrospective evaluation of acute hyperkalemia of unknown origin during general anesthesia in dogs

ObjectiveTo report and characterize cases of acute hyperkalemia of unknown origin in dogs under anesthesia. Study designMulticentric retrospective clinical study. AnimalsMedical records of 19 client-owned dogs that developed acute hyperkalemia during anesthesia. MethodsAnesthetic records of dogs developing acute hyperkalemia from January 2015 to December 2022 were evaluated. Data collected included demographics, duration of anesthesia until the episode, electrolytes and blood gas measurements, electrocardiogram (ECG) abnormalities, drugs used as part of the anesthetic protocol, hyperkalemia treatment and outcome. ResultsA total of 13 cases met the inclusion criteria with documented acute hyperkalemia with no apparent underlying cause during anesthesia. Dogs were [mean ± standard deviation (range)] 6.5 ± 5.0 (3–10) years old and weighed 18.0 ± 14.3 (5.1–40.0) kg. All dogs were administered dexmedetomidine and an opioid as part of the premedication. All dogs had inhalation anesthesia of >60 minutes’ duration. The first clinical sign was bradycardia that was minimally responsive to anticholinergic administration and was often accompanied by moderate/severe hypotension. These signs were rapidly followed by ECG changes compatible with hyperkalemia and/or cardiac arrest. Rapid identification and treatment for hyperkalemia, with or without dexmedetomidine reversal, resulted in survival of 12 dogs and one fatality. Conclusions and clinical relevanceUnknown origin hyperkalemia is a life-threatening complication that can occur during general anesthesia. In healthy dogs, preanesthetic administration of dexmedetomidine in association with an opioid and followed by inhalation anesthesia of more than 1 hour duration may predispose to this complication. A sudden decrease in heart rate >90 minutes after dexmedetomidine administration, or ECG changes, may warrant measurement of blood potassium concentrations.

Serum/plasma potassium monitoring using potentiometric point-of-care microanalyzers with improved ion selective electrodes

Different causes can trigger imbalances on homeostatic mechanisms between intracellular and extracellular compartments resulting in abnormal blood potassium concentrations (hypo or hyperkalemia). This can lead to serious consequences, even a life-threatening situation. Early diagnosis, treatment and follow-up are essential to minimize critical impacts in patients. Bedside determination of blood potassium is not accessible in all health care centers or in all emergency departments and far less common in this kind of centers in emerging countries. We have therefore proposed a portable, economic and long-lifetime potentiometric point-of-care (POC) analytical microsystem to deal with this question. It is a continuous flow microfluidic platform, made of cyclic olefin copolymer (COC), which combines microfluidics and a detection system based on the potentiometric technique containing a potassium selective electrode with a novel composition of polymeric membrane, which improves lifetime. Its size is smaller than a credit card and shows a linear range of Nernst calibration equation from 1 to 26 mM K+, a detection limit of 0.16 mM K+, a satisfactory repeatability and reproducibility, and an analysis frequency of 20 samples h−1, requiring only 25 μL as sample volume. Moreover, lifetime is as long as 9 months by intensive use. All these features comply with medical requirements. Human serum samples were analyzed with the developed device and the obtained results were compared with those provided by two methods: ICP-OES and another using ion selective electrodes. No significant differences were observed, demonstrating the suitability of the developed POC microanalyzer for bedside health applications.

Effect of inhaled albuterol on whole blood potassium concentrations in dogs.

Albuterol by inhalation (IH) is a common treatment for hyperkalemia in humans but its effect on blood potassium concentrations in dogs is unknown. Determine whether albuterol (IH) decreases blood potassium concentrations in healthy normokalemic dogs and if effects are dose-dependent. Ten healthy dogs. Prospective, crossover experimental study. Albuterol sulfate was administered at a low-dose (90 μg) in phase I and, 7 days later, high-dose (450 μg) in phase II. Blood potassium and glucose concentrations (measured via blood gas analyzer) and heart rates were obtained at baseline and then 3, 5, 10, 15, 30, 60, 90, 120, 180, and 360 minutes after inhaler actuation. Blood potassium concentrations decreased rapidly after albuterol delivery with a significant reduction compared to baseline within 30 minutes in both phases (P=.05). The potassium nadir concentration of phase I occurred at 60 minutes (mean, SD; 4.07 mmol/L, 0.4) and was significantly decreased from baseline, (4.30 mmol/L, 0.3; t(9)=2.40, P=.04). The potassium nadir concentration of phase II occurred at 30 minutes (mean, SD; 3.96 mmol/L, 0.39) and was also significantly decreased from baseline, (4.33 mmol/L, 0.4; t(9)=2.22, P=.05). The potassium nadir concentration decreased by 0.1 mmol/L for each 10μg/kg increase in dose of albuterol (P=.01). Five dogs had ≥1 hyperglycemic measurement (ie, >112 mg/dL). No median heart rate was tachycardic nor was any mean blood glucose concentration hyperglycemic at any time point. Albuterol IH decreases blood potassium concentrations in a dose-dependent manner without clinically meaningful alterations to heart rate or blood glucose concentrations in healthy dogs. The mean decrease in potassium concentration at the high-dose of albuterol was modest (0.38 mmol/L).

Comparison of the efficacy between Del Nido cardioplegia and HTK cardioplegia in Stanford type A aortic dissection patients undergoing open-heart surgery.

Acute Stanford type A aortic dissection is an extremely dangerous and life-threatening cardiovascular disease, usually treated with extracorporeal circulation heart surgery. Histidine-tryptophan-ketoglutarate (HTK) cardioplegia is a protective intracellular myocardial fluid that has been used extensively in different types of extracorporeal circulation surgeries. Del Nido cardioplegia is an extracellular myocardial protection fluid, which was first used in pediatric heart surgery and has been gradually used in a variety of pediatric and adult heart procedures. This study aims to compare the myocardial protection effect between Del Nido and HTK in patients undergoing extracorporeal circulation heart surgery for acute Stanford type A dissection and its impact on patients' prognosis by analyzing selected parameters and clinical manifestations at different time points. Clinical data were collected from 431 patients with acute Stanford type A dissection who were diagnosed and underwent surgery between January 1, 2018 and December 31, 2020 at Xiangya Hospital, Central South University. After excluding some of the data based on exclusion criteria, patients were divided into a HTK group and a Del Nido (DN) group based on type of intraoperative cardioplegia. Propensity score-matching was performed subsequently using the the R statistical software to determine the DN group ( n =40) and HTK group ( n =41). The matching factors were age, sex, hypertension, cardiopulmonary bypass time, and aortic occlusion time. Perioperative data, postoperative complications, blood gas data, and myocardial injury data were collected from the patients, and SPSS 26.0 was used to analyze the data of each group. The DN group had a higher rate of spontaneous cardioversion (41.5% vs 15.0%, P =0.005) and a lower postoperative hospital stay [10.0(8.0,14.0) d vs 13.0(11.0,19.0) d, P <0.05] compared to the HTK group. In terms of changes in blood gas analysis, immediate sodium and potassium concentrations were significantly higher in the DN group than that in the HTK group (both P <0.05). There was no significant difference in myocardial injury indexes between the two groups at different time points (all P >0.05). In terms of postoperative complications, the cardiac complications in DN group were much lower than those in the HTK Group (0 vs 12.5%, P =0.026). Del Nido cardioplegia has similar myocardial protective effects as HTK cardioplegia used in Stanford type A aortic dissection, with a higher rate of cardiac recurrence and fewer cardiac complications. Del Nido cardioplegia should play an important role in future application for acute Stanford type A aortic dissection, but our findings need to be further validated in a large sample of prospective clinical studies.

Weighted Time Warping Improves T-Wave Morphology Markers Clinical Significance.

T-wave (TW) morphology indices based on time-warping ( dw) have shown significant cardiovascular risk stratification value. However, errors in the location of TW boundaries may impact their prognostic power. Our aim was to test the hypothesis that a weighted time-warping function (WF) would reduce the sensitivity of dw to these errors and improve their clinical significance. The WFs were proportional to (i) the reference TW ( T), and (ii) the absolute value of its derivative ( D). The index dw was recalculated using these WFs, and its performance was compared to the unweighted control case ( C) in four different scenarios: 1) robustness against simulated TW boundaries location errors; 2) ability to retain physiological information in an electrophysiological cardiac model; 3) ability to monitor blood potassium concentration changes ( ∆[K+]) in 29 hemodialysis (HD) patients; 4) and the sudden cardiac death (SCD) risk stratification value of the TW morphology restitution (TMR) index, derived from dw, in 651 chronic heart failure (CHF) patients. The WFs led to a reduced sensitivity ( R) of dw to TW boundary location errors as compared to C (median R=0.19 and 0.22 and 0.35 for T, D and C, respectively). They also preserved the physiological relationship between dw and repolarization dispersion changes at ventricular level. No improvements in ∆[K+] tracking were observed for the HD patients (Pearson's median correlation [ r] between ∆[K+] and dw was 0.86 ≤ r ≤ 0.90 for T, D and C). In CHF patients, the SCD risk stratification value of TMR was improved by applying T (hazard ratio, HAR, of 2.80), followed by D (HAR=2.32) and C (HAR=2.23). The proposed WFs, with T showing the best performance, increased the robustness of time-warping based markers against TW location errors preserving their physiological information content and boosting their SCD risk stratification value. Results from this work support the use of T when deriving dw for future clinical applications.

Reducing the Fermentability of Wheat with a Starch Binding Agent Reduces Some of the Negative Effects of Heat Stress in Sheep.

Simple SummaryHeat stress is one of the major problems affecting the thermotolerance of livestock in Australia and in many parts of the world. Dietary interventions are considered to be one of the effective strategies to beat the heat. Hence, this study evaluated the benefits of reducing the fermentability of wheat grains (BioprotectTM) in the diet of Merino lambs. These results indicated that Bioprotect supplementation had a positive effect on the respiratory rate and heart rate of heat-stressed lambs.The objective of this study was to investigate the effects of reducing the fermentability of grains on thermoregulatory responses in heat stressed (HS) lambs. To achieve this, wheat grain treated with a commercial starch binding agent, Bioprotect, is compared to maize, which has already demonstrated effects in ameliorating heat stress-induced thermoregulation responses and untreated wheat grains. An initial in vitro experiment was conducted to examine cumulative gas production from the fermentation of wheat grain with different dosages of the commercial starch binding agent, Bioprotect. Based on the in vitro results, an in vivo lamb experiment was conducted using 24 Merino lambs (1 year old; 42.6 ± 3.6 kg BW). The lambs were offered one of three dietary treatments: a wheat-based diet (WD), a Bioprotect treated wheat-based diet (BD), and a maize-based diet (MD). Three successive 1-week experimental periods were conducted with lambs from all dietary groups (P1, P2, and P3). During P1, lambs were exposed to a TN environment and fed a 1.7× Maintenance feed intake (MF) level; in P2, lambs were kept in a HS environment and fed a 1.7× MF level; and in P3, animals were kept in a HS environment and fed a 2× MF level. The in vitro experiment revealed a reduction in cumulative gas production (p < 0.05) from the Bioprotect treated wheat compared to untreated wheat samples. In the in vivo component of the study, the replacement of wheat with maize or 2% Bioprotect-treated wheat reduced the respiration rate (p < 0.001) and heart rate (p ≤ 0.01) of lambs during HS. There was a reduction in the concentration of blood gas variables such as a base excess of blood (BE(b)) and extracellular fluid (BE(ecf)), bicarbonate (CHCO3−), the partial pressure of carbon dioxide (pCO2), the total concentration of carbon dioxide (ctCO2), and sodium (Na+) (p ≤ 0.001 for all) during the periods of HS compared to the thermoneutral conditions. Moreover, BD- and MD-fed lambs had a higher blood potassium concentration (K+) than the WD-fed lambs (p = 0.008). The results of the present study suggest that Bioprotect can be a viable feed treatment strategy for treating rapidly fermentable grains such as wheat to alleviate the effects of HS. Further, Bioprotect-treated wheat could be an option to replace maize in concentrate rations in jurisdictions where maize is cost-prohibitive or unavailable.

Perimortem dynamics of blood potassium concentration in patients dying in intensive care unit: A prospective nested cohort study.

To enable diagnosis of hyperkalemia from the perimortem blood sample, we aim to describe the natural dynamics of blood potassium [K+ ] in patients dying after withdrawal of care while in an intensive care unit. In a nested sub-study of international Death Prediction and Physiology after Removal of Therapy (DePPaRT) project, we obtained serial whole-blood samples and analyzed ions and acid-base parameters in 23 patients just before life-sustaining treatment withdrawal, at the time of death, and after 5 and 30 min after death. Of the 631 patients in the DePPaRT study, we obtained consent and enrolled 23 subjects in the [K+ ] sub-study (12 M, 11F, aged 73 ± 14 years), mostly dying from irreversible brain damage or multi-organ failure. Blood [K+ ] rose from the median 4.3 (IQR 3.9; 4.8) mEq/L at treatment withdrawal to 5.2 (IQR 5.0; 6.8) mEq/L at death and then to 5.85 (IQR 5.2; 6.8) mEq/L after 30 min (mean rise of +0.64 mEq.L-1 .h-1 ). These changes were associated with progressive lactic and hypercapnic acidemia. After correcting the measured [K+] for pH by subtracting 0.6mEq/L from [K+] for every 0.1 pH decrease from 7.40, the calculated [K+] remained normal or decreased from that measured at treatment withdrawal. In contrast to the late autolysis phase, the early changes of blood [K+ ] after death are slow and can be fully explained by progressive acidemia. Our data suggest that the diagnosis of hyperkalemia at death from a blood sample obtained within 30 min after death can be made by adjusting the [K+] concentration to a pH7.40.