Prolonged asystolic hyperkalemic cardiac arrest with no neurologic sequelae

Acute Hyperkalemia Management in the Emergency Department

Acute hyperkalemia is characterized by high concentrations of potassium in the blood that can potentially lead to life-threatening arrhythmias that require emergent treatment. Therapy involves the utilization of a constellation of different agents, all targeting different goals of care. The first, and most important step in the treatment of severe hyperkalemia with electrocardiographic (ECG) changes, is to stabilize the myocardium with calcium in order to resolve or mitigate the development of arrythmias. Next, it is vital to target the underlying etiology of any ECG changes by redistributing potassium from the extracellular space with the use of intravenous regular insulin and inhaled beta-2 agonists. Finally, the focus should shift to the elimination of excess potassium from the body through the use of intravenous furosemide, oral potassium-binding agents, or renal replacement therapy. Multiple nuances and controversies exist with these therapies, and it is important to have a robust understanding of the underlying support and recommendations for each of these agents to ensure optimal efficacy and minimize the potential for adverse effects and medication errors.

Lazarus Phenomenon or the Return from the Afterlife-What We Know about Auto Resuscitation

Autoresuscitation is a phenomenon of the heart during which it can resume its spontaneous activity and generate circulation. It was described for the first time by K. Linko in 1982 as a recovery after discontinued cardiopulmonary resuscitation (CPR). J.G. Bray named the recovery from death the Lazarus phenomenon in 1993. It is based on a biblical story of Jesus' resurrection of Lazarus four days after confirmation of his death. Up to the end of 2022, 76 cases (coming from 27 countries) of spontaneous recovery after death were reported; among them, 10 occurred in children. The youngest patient was 9 months old, and the oldest was 97 years old. The longest resuscitation lasted 90 min, but the shortest was 6 min. Cardiac arrest occurred in and out of the hospital. The majority of the patients suffered from many diseases. In most cases of the Lazarus phenomenon, the observed rhythms at cardiac arrest were non-shockable (Asystole, PEA). Survival time after death ranged from minutes to hours, days, and even months. Six patients with the Lazarus phenomenon reached full recovery without neurological impairment. Some of the causes leading to autoresuscitation presented here are hyperventilation and alkalosis, auto-PEEP, delayed drug action, hypothermia, intoxication, metabolic disorders (hyperkalemia), and unobserved minimal vital signs. To avoid Lazarus Syndrome, it is recommended that the patient be monitored for 10 min after discontinuing CPR. Knowledge about this phenomenon should be disseminated in the medical community in order to improve the reporting of such cases. The probability of autoresuscitation among older people is possible.

Electrocardiography is Unreliable to Detect Potential Lethal Hyperkalemia in Patients with Non-dialysis Chronic Kidney Disease

Hemodialysis patients with hypercalcemia are less likely to manifest the usual electrocardiographic changes associated with hyperkalemia than in those with normal renal function. This study was conducted to determine whether electrocardiography (ECG) is a reliable indicator to detect severe life-threatening hyperkalemia in non-dialysis CKD patients. The study was conducted at three referral university hospitals between July 2017 and June 2018. Severe hyperkalemia was defined as serum potassium concentration ≥ 8.0 mEq/L. Serum potassium, sodium, bicarbonate, calcium, and creatinine concentrations were measured and simultaneous 12-lead ECG was obtained. Patients with end-stage renal disease receiving renal replacement therapy were excluded. Also excluded were patients with the usual ECG abnormalities to hyperkalemia. Of the 438 patients screened, 10 (2.3%) aged 2-14 years with severe hyperkalemia and normal ECG findings were identified. Median serum potassium level was 8.6 mEq/L (range 8.2-9.0). All had regular sinus rhythm. P, QRS, ST segment, T morphology, PR and QT interval, and QRS duration were all normal. Hyperkalemia was associated with CKD, metabolic acidosis, and hypercalcemia in all cases. Therapy with intravenous 0.9% saline, sodium bicarbonate, glucose, insulin, calcium, and salbutamol corrected the hyperkalemia in 7 patients. The remaining three patients evinced arrhythmias requiring hemodialysis. Although rare, non-dialysis CKD patients with hypercalcemia may not manifest the usual electrographic abnormalities associated with hyperkalemia. Thus, a normal ECG finding in non-dialysis CKD patients should be interpreted with caution.

Risen Alive: The Lazarus Phenomenon

The Lazarus phenomenon described as delayed return of spontaneous circulation (ROSC) after cessation of CPR is rare, though underreported. We present the case of a 25-year-old woman who visited our hospital for persistent vomiting and weight loss for the last six months following bariatric surgery. On the 16^th day of admission, the patient experienced cardiac arrest (code blue). The patient underwent 73 min of continuous cardiopulmonary resuscitation (CPR); however, no responses were observed, which led to an announcement of death. Fifty minutes later, the family members noticed subtle eye movements that necessitated resumption of the advanced cardiac life support protocol and resuscitation. The patient survived; however, she developed significant neurological deficits secondary to prolonged anoxic brain injury. She was discharged after a ten-week stay in the hospital but did not achieve full neurologic, cognitive, and motor recovery. Patients should be observed and monitored after the cessation of CPR before confirming death.

Lazarus Phenomenon: Return of Spontaneous Circulation After Cessation of Prolonged Cardiopulmonary Resuscitation in a Patient With COVID-19

The pandemic caused by the SARS-CoV-2 or COVID-19 infection has had an unimaginable impact on health systems worldwide. Cardiorespiratory arrest remains a potentially reversible medical emergency that requires the performance of a set of maneuvers designed to replace and restore spontaneous breathing and circulation. Suspending cardiopulmonary resuscitation (CPR) usually corresponds to an ethical-clinical dilemma that the health professional in charge must assume. The “Lazarus phenomenon” is an unusual syndrome with a difficult pathophysiological explanation, defined as the spontaneous return of circulation in the absence of any life support technique or after the cessation of failed CPR maneuvers.

We present the case of a 79-year-old patient hospitalized in the intensive care unit for septic shock of pulmonary origin associated with COVID-19 infection who presented cardiorespiratory arrest that required unsuccessful resuscitation maneuvers for 40 minutes, declared deceased. After 20 minutes of death, he presented a return to spontaneous circulation.

The pathophysiological changes of the Lazarus phenomenon remind us of the limitations we have in determining when to end cardiopulmonary resuscitation and that its interruption must be approached with more caution, especially in the context of the COVID-19 pandemic.

Atypical electrocardiographic findings in severe hyperkalemia with slow clinical course

A 77-year-old woman walked into the emergency department with an episode of syncope and vomiting. She had visited at an orthopedic clinic with weakness of the lower extremities 6 weeks before, but cervical and lumbar MRI findings were unremarkable. Thereafter, she developed fingertip numbness and appetite loss at 7 and 3 days, respectively, before admission. She had been prescribed with RAS inhibitors for years. Electrocardiography while in the emergency department revealed bradycardia with normal QRS and a tented T wave. Laboratory findings revealed serum potassium 9.2 mEq/L. We discontinued RAS inhibitors and β-blockers and added glucose-insulin therapy. Thereafter, her general condition gradually recovered, and her symptoms completely disappeared. Elderly patients with chronic kidney disease treated with RAS inhibitors might develop slowly progressive symptoms of hyperkalemia. Electrocardiographic findings could be atypical and inconsistent with serum potassium values.

Autoresuscitation (Lazarus phenomenon) after termination of cardiopulmonary resuscitation - a scoping review

BACKGROUND

Autoresuscitation describes the return of spontaneous circulation after termination of resuscitation (TOR) following cardiac arrest (CA). We aimed to identify phenomena that may lead to autoresuscitation and to provide guidance to reduce the likelihood of it occurring.

MATERIALS AND METHODS

We conducted a literature search (Google Scholar, MEDLINE, PubMed) and a scoping review according to PRISMA-ScR guidelines of autoresuscitation cases where patients undergoing CPR recovered circulation spontaneously after TOR with the following criteria: 1) CA from any cause; 2) CPR for any length of time; 3) A point was reached when it was felt that the patient had died; 4) Staff declared the patient dead and stood back. No further interventions took place; 5) Later, vital signs were observed. 6) Vital signs were sustained for more than a few seconds, such that staff had to resume active care.

RESULTS

Sixty-five patients with ROSC after TOR were identified in 53 articles (1982-2018), 18 (28%) made a full recovery.

CONCLUSIONS

Almost a third made a full recovery after autoresuscitation. The following reasons for and recommendations to avoid autoresuscitation can be proposed: 1) In asystole with no reversible causes, resuscitation efforts should be continued for at least 20 min; 2) CPR should not be abandoned immediately after unsuccessful defibrillation, as transient asystole can occur after defibrillation; 3) Excessive ventilation during CPR may cause hyperinflation and should be avoided; 4) In refractory CA, resuscitation should not be terminated in the presence of any potentially-treatable cardiac rhythm; 5) After TOR, the casualty should be observed continuously and ECG monitored for at least 10 min.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Current treatment and unmet needs of hyperkalaemia in the emergency department

Hyperkalaemia is a common electrolyte abnormality and can cause life-threatening cardiac arrhythmia. Even though it is common in patients with diabetes, heart failure, and kidney disease, there is poor consensus over its definition and wide variability in its treatment. Medications used to treat hyperkalaemia in the emergent setting do not have robust efficacy and safety data to guide treatment leading to mismanagement due to poor choice of some agents or inappropriate dosing of others. Moreover, the medications used in the emergent setting are at best temporizing measures, with dialysis being the definitive treatment. New and old k binder therapies provide means to excrete potassium, but their roles are unclear in the emergent setting. Electrocardiograms are the corner stones of hyperkalaemia management; however, recent studies show that they might manifest abnormalities infrequently, even in severe hyperkalaemia, thus questioning their role. With an aging population and a rise in rates of heart and kidney failure, hyperkalaemia is on the rise, and there is a need, now more than ever, to understand the efficacy and safety of the current medications and to develop newer ones.

Hyperkalemia masked by pseudo-stemi infarct pattern and cardiac arrest

Background

Hyperkalemia is a common electrolyte abnormality and has well-recognized early electrocardiographic manifestations including PR prolongation and symmetric T wave peaking. With severe increase in serum potassium, dysrhythmias and atrioventricular and bundle branch blocks can be seen on electrocardiogram. Although cardiac arrest is a worrisome consequence of untreated hyperkalemia, rarely does hyperkalemia electrocardiographically manifest as acute ischemia.

Case presentation

We present a case of acute renal failure complicated by malignant hyperkalemia and eventual ventricular fibrillation cardiac arrest. Recognition of this disorder was delayed secondary to an initial ECG pattern suggesting an acute ST segment elevation myocardial infarction (STEMI). Emergent coronary angiography performed showed no evidence of coronary artery disease.

Conclusions

Pseudo-STEMI patterns are rarely seen in association with acute hyperkalemia and are most commonly described with patient without acute cardiac symptomatology. This is the first such case presenting concurrently with cardiac arrest. A brief review of this rare pseudo-infarct pattern is also given.

Potassium Homeostasis, Oxidative Stress, and Human Disease

Potassium is the most abundant cation in the intracellular fluid and it plays a vital role in the maintenance of normal cell functions. Thus, potassium homeostasis across the cell membrane, is very critical because a tilt in this balance can result in different diseases that could be life threatening. Both Oxidative stress (OS) and potassium imbalance can cause life threatening health conditions. OS and abnormalities in potassium channel have been reported in neurodegenerative diseases. This review highlights the major factors involved in potassium homeostasis (dietary, hormonal, genetic, and physiologic influences), and discusses the major diseases and abnormalities associated with potassium imbalance including hypokalemia, hyperkalemia, hypertension, chronic kidney disease, and Gordon's syndrome, Bartter syndrome, and Gitelman syndrome.

Review and Outcome of Prolonged Cardiopulmonary Resuscitation

The maximal duration of cardiopulmonary resuscitation (CPR) is unknown. We report a case of prolonged CPR. We have then reviewed all published cases with CPR duration equal to or more than 20 minutes. The objective was to determine the survival rate, the neurological outcome, and the characteristics of the survivors. Measurements and Main Results. The CPR data for 82 patients was reviewed. The median duration of CPR was 75 minutes. Patients mean age was 43 ± 21 years with no significant comorbidities. The main causes of the cardiac arrests were myocardial infarction (29%), hypothermia (21%), and pulmonary emboli (12%). 74% of the arrests were witnessed, with a mean latency to CPR of 2 ± 6 minutes and good quality chest compression provided in 96% of the cases. Adjunct therapy included extracorporeal membrane oxygenation (18%), thrombolysis (15.8%), and rewarming for hypothermia (19.5%). 83% were alive at 1 year, with full neurological recovery reported in 63 patients. Conclusion. Patients undergoing prolonged CPR can survive with good outcome. Young age, myocardial infarction, and potentially reversible causes of cardiac arrest such as hypothermia and pulmonary emboli predict a favorable result, especially when the arrest is witnessed and followed by prompt and good resuscitative efforts.

Donation after cardiac death and the emergency department: ethical issues

Organ donation after cardiac death (DCD) is increasingly considered as an option to address the shortage of organs available for transplantation, both in the United States and worldwide. The procedures for DCD differ from procedures for donation after brain death and are likely less familiar to emergency physicians (EPs), even as this process is increasingly involving emergency departments (EDs). This article explores the ED operational and ethical issues surrounding this procedure.

Donation after cardiocirculatory death: a call for a moratorium pending full public disclosure and fully informed consent

Many believe that the ethical problems of donation after cardiocirculatory death (DCD) have been "worked out" and that it is unclear why DCD should be resisted. In this paper we will argue that DCD donors may not yet be dead, and therefore that organ donation during DCD may violate the dead donor rule. We first present a description of the process of DCD and the standard ethical rationale for the practice. We then present our concerns with DCD, including the following: irreversibility of absent circulation has not occurred and the many attempts to claim it has have all failed; conflicts of interest at all steps in the DCD process, including the decision to withdraw life support before DCD, are simply unavoidable; potentially harmful premortem interventions to preserve organ utility are not justifiable, even with the help of the principle of double effect; claims that DCD conforms with the intent of the law and current accepted medical standards are misleading and inaccurate; and consensus statements by respected medical groups do not change these arguments due to their low quality including being plagued by conflict of interest. Moreover, some arguments in favor of DCD, while likely true, are "straw-man arguments," such as the great benefit of organ donation. The truth is that honesty and trustworthiness require that we face these problems instead of avoiding them. We believe that DCD is not ethically allowable because it abandons the dead donor rule, has unavoidable conflicts of interests, and implements premortem interventions which can hasten death. These important points have not been, but need to be fully disclosed to the public and incorporated into fully informed consent. These are tall orders, and require open public debate. Until this debate occurs, we call for a moratorium on the practice of DCD.

The Lazarus phenomenon

Even though Lazarus phenomenon is rare, it is probably under reported. There is no doubt that Lazarus phenomenon is a reality but so far the scientific explanations have been inadequate. So far the only plausible explanation at least in some cases is auto-PEEP and impaired venous return. In patients with PEA or asystole, dynamic hyperinflation should considered as a cause and a short period of apnoea (30-60 seconds) should be tried before stopping resuscitation. Since ROSC occurred within 10 minutes in most cases, patients should be passively monitored for at least 10 minutes after the cessation of CPR before confirming death.

The Lazarus phenomenon

Even though Lazarus phenomenon is rare, it is probably under reported. There is no doubt that Lazarus phenomenon is a reality but so far the scientific explanations have been inadequate. So far the only plausible explanation at least in some cases is auto-PEEP and impaired venous return. In patients with PEA or asystole, dynamic hyperinflation should considered as a cause and a short period of apnoea (30-60 seconds) should be tried before stopping resuscitation. Since ROSC occurred within 10 minutes in most cases, patients should be passively monitored for at least 10 minutes after the cessation of CPR before confirming death.

Spontaneous defibrillation after cessation of resuscitation in out-of-hospital cardiac arrest: A case of Lazarus phenomenon

This report describes a case of out-of-hospital cardiac arrest with spontaneous defibrillation and subsequent return of circulation after cessation of resuscitative efforts. A 47-year-old man was found in cardiac arrest and resuscitation was initiated. As no response was achieved, the efforts were withdrawn and final registered cardiac rhythm was ventricular fibrillation. Fifteen minutes later the patient was found to be normotensive and breathing spontaneously. The patient made a poor neurological recovery and died 3 months after the arrest. The authors are unable to give an explanation to the event, but suspect the effect of adrenaline combined with mild hypothermia to have contributed to the self-defibrillation of the myocardium.

Potassium disorders—clinical spectrum and emergency management

Potassium disorders are common and may precipitate cardiac arrhythmias or cardiopulmonary arrest. They are an anticipated complication in patients with renal failure, but may also occur in patients with no previous history of renal disease. They have a broad clinical spectrum of presentation and this paper will highlight the life-threatening arrhythmias associated with both hyperkalaemia and hypokalaemia. Although the medical literature to date has provided a foundation for the therapeutic options available, this has not translated into consistent medical practice. Treatment algorithms have undoubtedly been useful in the management of other medical emergencies such as cardiac arrest and acute asthma. Hence, we have applied this strategy to the treatment of hyperkalaemia and hypokalaemia which may prove valuable in clinical practice.

Irreversible apnoeic coma 35 years later. Towards a more rigorous definition of brain death?

The concept of brain death (BD) has been widely accepted by medical and lay communities in the Western world and is the basis of policies of organ retrieval for transplantation from brain-dead donors. Nevertheless, concerns still exist over various aspects of the clinical condition it refers to. They include the utilitarian origin of the concept, the substantial international variation in BD definitions and criteria, the equivalence between BD and the donor's biological death, the practice of retrieving organs from donors who are not brain-dead (as in non-heart-beating organ donor protocols), the proposal to abandon the dead donor rule and attempts to overcome these problems by adapting rules and definitions. Suggesting that BD, as it was originally proposed by the Harvard Committee, is more a moral than a scientific concept, we argue that current criteria do not empirically justify the definition of BD; yet they consistently identify a clinical condition in which organ retrieval can be morally and socially justified. We propose to revert to the old term of "irreversible coma" or, better yet, of "irreversible apnoeic coma", thus abandoning the presumption of diagnosing the death of all intracranial neurons and/or the patient's biological death. On the other hand, we think that a (re)definition of the vital status of donors identified on neurological criteria can only occur through a prior (re)definition of death, a task which is not only medical but societal.

Death following spontaneous recovery from cardiopulmonary arrest in a hospital mortuary: 'Lazarus phenomenon' in a case of alleged medical negligence

We report a possibly first forensic autopsy case of death following a spontaneous recovery from cardiopulmonary arrest (CPA) after clinical declaration of death: 'Lazarus phenomenon'. A 65-year-old male with congenital deafness and dumbness was found unconscious in his room at a public home. During pre-hospital and clinical resuscitation including defibrillation and medications for about 35 min, CPA persisted under electrocardiographic (ECG) monitoring and therefore, his death was pronounced. However, about 20 min later, a police officer who had been called for the postmortem investigation found the patient moving in the mortuary. The patient subsequently showed typical ECG signs and laboratory findings of early inferior wall myocardial infarction and died 4 days later. The forensic autopsy, due to alleged medical negligence, revealed myocardial infarction with thrombotic occlusion of the right coronary artery and secondary hypoxic brain damage. The present case and the related clinical literature suggest that, especially in cases of acute myocardial infarction in elderly patients, a careful observation to confirm death after discontinuation of resuscitation is recommended to provide appropriate medical care, irrespective of the quality or duration of advanced life supporting efforts.

Lidocaine-induced conduction disturbance in patients with systemic hyperkalemia

We report 2 cases in which lidocaine, given for wide-complex tachycardia in the presence of hyperkalemia, precipitated profound conduction disturbance and asystole. The electrophysiologic effects of hyperkalemia and its interaction with lidocaine are reviewed. In patients with known hyperkalemia and wide-complex tachycardia, treatment should be directed at hyperkalemia, rather than following treatment algorithms for wide-complex tachycardia.

Severe hyperkalemia with minimal electrocardiographic manifestations: a report of seven cases

Severe hyperkalemia with minimal or nonspecific electrocardiographic (ECG) changes is unusual. We report data on seven patients with renal failure, metabolic acidosis, and severe hyperkalemia (K+ > or =8 mmol/L) without typical ECG changes. Initial ECGs revealed sinus rhythm and PR and QT intervals in the normal range. QRS intervals were slightly prolonged in two patients (110 ms), and incomplete right bundle branch block was evident in one. Thus, the absence of typical ECG changes does not preclude severe hyperkalemia.

Unexpected return of spontaneous circulation after cessation of resuscitation (Lazarus phenomenon)

Since 1982, more than 20 patients with return of spontaneous circulation after cessation of cardiopulmonary resuscitation (Lazarus phenomenon) have been published. We report on another case here. Such cases are probably underreported due to medicolegal concerns. After cessation of resuscitation, each patient should be further monitored for at least 10 min to detect a possible Lazarus phenomenon.

Hyperkalemic cardiac arrest during anesthesia in infants and children with occult myopathies

In 1992, the Malignant Hyperthermia Association of the United States and The North American Malignant Hyperthermia Registry received reports of cardiac arrest in apparently healthy children given succinylcholine. Using data from 1990 to 1993, this study analyzes: (1) etiology of all reported pediatric arrests and (2) whether survival was associated with certain patient or treatment variables. We reviewed retrospectively all reports of pediatric (age < 18 years) arrests occurring within 24 hours of anesthesia. Etiology of arrests and presence of myopathy were determined. Twenty-five patients (92% male, median 45 months old) arrested; 23/25 (92%) were scheduled for minor surgery. Before receiving a potent inhalational anesthetic (92%) and/or succinylcholine (72%), these patients were evaluated by the anesthesiologist as being healthy with no personal or family history of myopathy. Serum potassium during arrest was measured in 18/25 (72%) patients; hyperkalemia (mean [K+] = 7.4 +/- 2.8, median 7.5 mmol/L) was detected in 13/18 (72%) patients. Postarrest resuscitations lasted a median of 42 minutes (range 10-296). Ten (40%) patients died, 1 (4%) is vegetative, and 14 (56%) returned to baseline neurologic function. A previously unrecognized Duchenne dystrophy (n = 8) or unspecified myopathy (n = 4) was diagnosed in 12 (48%) patients. Eight of these 12 patients' arrests were associated with hyperkalemia. Ten (40%) patients had no postarrest evaluation to exclude occult myopathy. No patient or treatment variables were statistically associated with survival. We conclude that, whenever possible, pediatricians should evaluate their patients (especially male infants and children) preoperatively for the presence of occult myopathy. During perianesthetic resuscitations, the pediatric advanced life support protocol should be modified to detect and treat hyperkalemia, a potentially reversible state even after prolonged resuscitation efforts. Following anesthetic deaths, pathologists should examine body fluid electrolytes and skeletal muscle for myopathy and dystrophin. If a preanesthetic creatine kinase screen for myopathy in male patients and restrictions on succinylcholine had been used, 64% of arrests and 60% of deaths might have been prevented. A formal prospective risk/benefit analysis for preventive measures is needed.

Disturbances of potassium homeostasis in poisoning

Unless renal function is impaired or rhabdomyolysis is severe, hyperkalemia is a relatively uncommon metabolic complication of poisoning. In contrast, marked hypokalemia is a more common problem and may have serious sequelae. Most potassium disturbances in acute poisoning are due to disruption of extra-renal control mechanisms, notably the activity of Na+/K+ ATPase and K+ channels. Hypokalemia occurs because of increased Na+/K+ ATPase activity (e.g. beta 2 agonist, theophylline or insulin poisoning), competitive blockade of K+ channels (e.g. barium or chloroquine poisoning), gastrointestinal losses and/or alkalosis. Hyperkalemia follows inhibition of Na+/K+ ATPase activity (e.g. by digoxin), increased uptake of potassium salts, disruption of intermediary metabolism (e.g. cyanide poisoning), activation of K+ channels (e.g. fluoride poisoning), and the presence of acidosis and rhabdomyolysis, particularly if the latter is complicated by renal failure. Hypokalemia results in generalized muscle weakness, paralytic ileus, ECG changes (flat or inverted T waves, prominent U waves, ST segment depression) and cardiac arrhythmias (atrial tachycardia +/- block, AV dissociation, VT, VF). Hyperkalemia is associated with abdominal pain, diarrhea, muscle pain and weakness, ECG changes (tall peaked T waves, ST segment depression, prolonged PR interval, QRS prolongation) and cardiac arrhythmias (VT, VF). Significant disturbances of potassium homeostasis are often unrecognized and may cause considerable morbidity and mortality. Prompt recognition and appropriate treatment of these disturbances could be life-saving.