The emergency treatment of hyperkalemia

Clinical and electrocardiogram presentations of patients with high serum potassium concentrations within emergency settings: a prospective study

BACKGROUND

Elevated potassium level is a common and reversible peri-arrest condition. Diagnosis and management of hyperkalemia in a short time is critical, where electrocardiogram (ECG) alterations might be helpful. We aimed to investigate the role of clinical features and ECGs in early diagnosing and treating hyperkalemia.

METHODS

Prospectively, adult patients who presented to the emergency department (ED) from July 2019 to March 2020 with hyperkalemia (serum potassium ≥5.5mmol/L) were included. History was obtained, and laboratory investigations and ECGs were performed at the presentation and before initiating hyperkalemia therapy. Hyperkalemia severity was divided into mild (5.5-5.9mmol/L), moderate (6.0-6.4mmol/L), and severe (≥6.5mmol/L). A cardiologist and emergency physician blinded to laboratory values, study design, and patients' diagnoses interpreted ECGs and presenting symptoms independently to predict hyperkalemia.

RESULTS

Sixty-seven hyperkalemic patients with a mean (±SD) serum potassium level of 6.5±0.7mmol/L were included in this study. The mean age was 63.9±15.1, and 58.2% were females. Hyperkalemia was mild in 10.4%, moderate in 40.3%, and severe in 49.3%. Almost two thirds of patients (71.6%) had hypertension, 67.2% diabetes, and 64.2% chronic kidney disease. About one-quarter of patients (22.4%) were asymptomatic, while fatigue (46.3%), dyspnea (28.4%), and nausea/vomiting (20.9%) were the most common presenting symptoms. Normal ECGs were observed in 25.4% of patients, while alterations in 74.6%. Atrial fibrillation (13.4%), peaked T wave (11.9%), widened QRS (11.9%), prolonged PR interval (10.5%), and flattening P wave (10.5%) were the most common. Peaked T wave was significantly more common in severe hyperkalemia (87.5%) than in mild and moderate hyperkalemia (12.5%, 0.0%, respectively) (p=0.041). The physicians' sensitivities for predicting hyperkalemia were 35.8% and 28.4%, improved to 51.5% and 42.4%, respectively, when limiting the analyses to severe hyperkalemia. The mean (±SD) time to initial hyperkalemia treatment was 63.8±31.5 min. Potassium levels were positively correlated with PR interval (r=0.283, p=0.038), QRS duration (r=0.361, p=0.003), peaked T wave (r=0.242, p=0.041), and serum levels of creatinine (r=0.347, p=0.004), BUN (r=0.312, p=0.008), and CK (r=0.373, p=0.039).

CONCLUSIONS

The physicians' abilities to predict hyperkalemia based on ECG and symptoms were poor. ECG could not be solely relied on, and serum potassium tests should be conducted for accurate diagnosis.

High-dose calcium reduces early-onset hyperkalemia in extremely preterm neonates

BACKGROUND

Early-onset hyperkalemia often occurs in extremely preterm infants during a few days after birth. While there are several treatments for hyperkalemia, calcium infusion to reduce plasma potassium concentrations remains controversial. The purpose of this study is to investigate whether a high dosage of calcium reduces early-onset hyperkalemia.

METHODS

Extremely low-birthweight neonates born at 22-25 weeks' gestation were enrolled. We analyzed data using multivariate regression analysis and performed a retrospective cohort study with patients divided into two groups according to the dosage of calcium in their initial infusion.

RESULTS

A total of 103 patients were eligible. Early-onset hyperkalemia was observed in 27 patients. The dosage of calcium gluconate during 24 h after birth was the only independent factor affecting early-onset hyperkalemia. The maximum plasma potassium concentration during 72 h after birth was negatively correlated with the dosage of calcium. High-dose calcium reduced occurrences of hyperkalemia and hypoglycemia caused by insulin infusion given for treatment of hyperkalemia, without increasing the risk of any other complications.

CONCLUSIONS

Infusion of calcium gluconate may reduce early-onset hyperkalemia in a dose-dependent manner.

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.

Prediction of hyperkalemia in dogs from electrocardiographic parameters using an artificial neural network

OBJECTIVE

To predict severe hyperkalemia from single electrocardiogram (ECG) tracings.

METHODS

Ten conditioned dogs each underwent this protocol three times: Under isoflurane anesthesia, 2 mEq/kg/hr of potassium chloride was given intravenously until P-waves were absent from the ECG and ventricular rates decreased > or =20% in < or =5 minutes. Serum potassium levels (K(+)) were measured at regular intervals with concurrent digital storage of lead II of the surface ECG. A three-layer artificial neural network with four hidden nodes was trained to predict K(+) from 15 separate elements of corresponding ECG data. Data were divided into a training set and a test set. Sensitivity, specificity, and diagnostic accuracy for recognizing hyperkalemia were calculated for the test set based on a prospectively defined K(+) = 7.5.

RESULTS

The model produced data for 189 events; 139 were placed in the training set and 50 in the test set. The test set had 37 potassium levels at or above 7.5 mmol/L. The neural network had a sensitivity of 89% (95% CI = 75% to 97%) and a specificity of 77% (95% CI = 46% to 95%) in recognizing these. The positive likelihood ratio was 3.87. Overall accuracy of this model was 86% (95% CI = 73% to 94%). Mean (+/-SD) difference between predicted and actual K(+) values was 0.4 +/- 2.0 (95% CI = -0.2 to 1.0).

CONCLUSIONS

An artificial neural network can accurately diagnose experimental hyperkalemia using ECG parameters. Further work could potentially demonstrate its usefulness in bedside diagnosis of human subjects.

The effects of verapamil and diltiazem pretreatment on potassium release in dogs after the administration of succinylcholine

Verapamil exacerbates the increase in serum potassium after a large-dose potassium infusion or after the IV administration of succinylcholine. We conducted a study in 12 canines conditioned for 30 days acting as their own controls. The canines had chronic tracheotomies and carotid loops performed 2 wk before the experiment. Control canines were given 1 mg/kg succinylcholine at Time 0. Blood samples were analyzed for potassium at 0, 1, 3, 5, 10, 15, 30, and 60 min. One week later, the dogs received 0.15 mg/kg of either verapamil or diltiazem, followed by a 5.6-microg x kg(-1) x min(-1) 10-min infusion of the same drug. The animals were then given a bolus dose of succinylcholine 1 mg/kg, and the blood potassium was analyzed as before. There was no significant difference in the potassium concentration before the succinylcholine injection (Time 0) between the study groups. The canines pretreated with verapamil had a significantly greater increase (24% +/- 8%) in potassium concentration than the control canines (14% +/- 6%) 15 min after succinylcholine administration. There was no difference between the potassium concentrations of the diltiazem-pretreated canines and the control group at any time point. Therefore, diltiazem pretreatment does not significantly influence potassium regulation after a succinylcholine injection, whereas verapamil pretreatment has measurable hyperkalemic effects.

IMPLICATIONS

Succinylcholine is a drug that causes blood potassium to increase. Potassium influences heart rhythm. Verapamil and diltiazem are drugs used for angina heart pain. We used dogs to determine the effect of verapamil or diltiazem on the blood's potassium after an injection of succinylcholine and found that verapamil had the greatest effect.

Potassium and anaesthesia

Potassium is the principle intracellular ion, and its concentration and gradients greatly influence the electrical activity of excitable membranes. Because anaesthesia is so intimately involved with electrically active cells, potassium concentrations in surgical patients have received considerable attention in diagnostic and therapeutic applications. With the ongoing evolution in the indications for potassium, it is important to review the role of potassium in cellular activity, in storage and regulation, in diseases that alter potassium homeostasis, and in the therapeutic implications of perioperative alterations of potassium concentration. A rational approach to abnormal potassium values and the use of potassium in the operating room is sought, based on a physiological understanding of risks and benefits.

The ability of physicians to predict hyperkalemia from the ECG

STUDY OBJECTIVE

To determine whether physicians blinded to the serum potassium level can predict hyperkalemia (potassium concentration of more than 5.0 mmol/L) from the ECG.

DESIGN

ECGs of patients at high risk for hyperkalemia were interpreted retrospectively by two physicians blinded not only to the specific clinical diagnosis of the patient and to their serum potassium measurement but also to each other's interpretation. The physicians predicted the presence or absence of hyperkalemia as well as the severity of hyperkalemia on a nominal scale (mild, moderate, or severe).

SETTING

The emergency department of a university-affiliated urban county hospital.

PATIENTS

Two hundred twenty consecutive patients admitted to the hospital from the ED with a diagnosis of renal failure or hyperkalemia. Eighty-seven patients had hyperkalemia, and 133 did not.

RESULTS

The sensitivities of the readers for predicting hyperkalemia were .43 and .34, respectively (best positive predictive value, .65). The respective specificities for detecting hyperkalemia were .85 and .86 (best negative predictive value, .69). When only patients with moderate-to-severe hyperkalemia (potassium of more than 6.5 mmol/L) were analyzed, sensitivities were .62 and .55. The readers' ability to predict the severity of hyperkalemia was equally poor.

CONCLUSION

The ECG is not a sensitive method of detecting hyperkalemia, even in high-risk patients. The specificity of the ECG is better for hyperkalemia, but empiric treatment of hyperkalemia based on the ECG alone will lead to mistreatment of at least 15% of patients.

Effect of hyperkalemia on experimental myocardial depression by verapamil

Three patients with systemic hypotension and sinus bradycardia that were initially refractory to conventional therapy responded well to intravenous calcium administration. Two-dimensional echocardiography revealed immediate reversal of severe left ventricular dysfunction after intravenous administration of calcium in two instances. Common factors were hyperkalemia and verapamil therapy. This interaction was examined further by evaluation of contractility, heart rate, and arterial blood pressure in anesthetized dogs. Controls (n = 9) received saline infusion, and a second group (n = 10) received saturated potassium chloride (approximately 0.2 ml/min intravenously). In control dogs, administration of verapamil (1195 +/- 181 micrograms/kg intravenously) reduced systemic arterial pressure from 113 +/- 7 mm Hg to 74 +/- 5 mm Hg, and heart rate from 147 +/- 9 beats/min to 86 +/- 11 beats/min. Potassium chloride infusion alone increased blood [K+] from 3.4 +/- 0.1 to 6.2 +/- 0.2 mEq/L, but was without hemodynamic effects. In hyperkalemic dogs, a significantly lower dose of verapamil (428 +/- 42 micrograms/kg intravenously) reduced systemic arterial pressure from 102 +/- 8 mm Hg to 36 +/- 4 mm Hg, and heart rate from 150 +/- 5 beats/min to 104 +/- 15 beats/min. Myocardial contractile function was examined with right ventricular isometric contractile force and left ventricular segment length changes. In normokalemic and hyperkalemic groups, contractility was decreased by verapamil. Effects of verapamil on arterial pressure and contractility could be reversed significantly by administration of calcium, 0.4 mEq/kg intravenously. The present results support the theory that the negative hemodynamic effects of verapamil may be exaggerated to a harmful degree by concomitant hyperkalemia. These adverse events may be reversed by calcium administration.

Disorders of potassium homeostasis

Hypokalemia and hyperkalemia are common problems that may be artifactual, iatrogenic, or due to altered body homeostatic mechanisms. ECG may help one to recognize hyperkalemia but not hypokalemia. Excessive K supplementation is a common iatrogenic cause of hyperkalemia whereas fluid therapy is a common cause of iatrogenic hypokalemia. The most common causes of spontaneous hyperkalemia are renal failure and hypoadrenocorticism whereas the most common causes of spontaneous hypokalemia are vomiting, diarrhea, and renal wasting. Symptomatic therapy is usually done until the underlying cause(s) is resolved.

Complications following oral administration of exchange resins in extremely low-birth-weight infants

Complications of the oral use of sodium polystyrene sulfonate and calcium polystyrene sulfonate are reported in five extremely low-birth-weight infants in which exchange resins were used to treat hyperkalemia. Radio opaque masses outlining the stomach were seen in all infants and could be palpated in the left upper quadrant of the abdomen. In two infants, at autopsy the palpable mass could be identified as a solid chalk-like concretion outlining the stomach. X-ray diffraction studies identified the material as Brushite. Administration of exchange resins by the gastric route should be avoided in the treatment of hyperkalemia in critically sick, extremely low-birth-weight infants.

Hyperkalaemic cardiac arrest following intravenous hydralazine and propranolol therapy post-embolectomy

A case of hyperkalaemic cardiac arrest occurring in a 50-year-old woman after bilateral femoral embolectomies is presented. The postoperative course was complicated by acute renal failure, metabolic acidosis, hypotension and low cardiac output. The possible contribution of hydralazine and propranolol therapy to the rapid development of hyperkalaemia is discussed.

Mannitol, osmolality and steroids during renal transplantation. Real and theoretical influences on plasma potassium

Mannitol did not have an exaggerated effect on plasma potassium when administered to twelve patients undergoing renal transplantation. Unexpected rises in plasma osmolality, greater than those recorded after mannitol, were observed in two of the patients. In these two patients the osmolality changes were due to sudden hyperglycaemia and followed methylprednisolone therapy (given for immunosuppression). It is suggested that under certain circumstances, such changes in osmolality may lead to a rise in plasma potassium comparable to the effect of mannitol. One of the two patients with the rise in glucose and osmolality did have a rise in plasma potassium.