Accidental Hypothermia: 2021 Update

Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient arrests, continuous cardiopulmonary resuscitation (CPR) should be performed. In hypothermic patients, the chances of survival and good neurological outcome are higher than for normothermic patients for witnessed, unwitnessed and asystolic cardiac arrest. Mechanical CPR devices should be used for prolonged rescue, if available. In severely hypothermic patients in cardiac arrest, if continuous or mechanical CPR is not possible, intermittent CPR should be used. Rewarming can be accomplished by passive and active techniques. Most often, passive and active external techniques are used. Only in patients with refractory hypothermia or cardiac arrest are internal rewarming techniques required. ECLS rewarming should be performed with extracorporeal membrane oxygenation (ECMO). A post-resuscitation care bundle should complement treatment.

The use of vagal manoeuvres in narrow complex tachyarrhythmias in primary care

Supraventricular tachydysrhythmias (SVTs) are a common presenting complaint, with a national prevalence of 3/1000 persons. Whilst most commonly stable, prolonged paroxysms can deteriorate into haemodynamically unstable subtypes or ventricular dysrhythmias. Early recognition with appropriate management is critical to reducing the morbidity associated with this condition. The American Heart Association holds that vagal manoeuvres are a first-line therapy in the management algorithm of stable SVTs. However, they state that no clear recommendations can be made around which manoeuvre to use, highlighting that future research should examine the efficacy and safety profiles of the various manoeuvres. In the South African primary care setting, clinicians must be at the forefront of pragmatic management strategies in the face of resource limitations, such as the unavailability of adenosine – a second-line therapy when vagal manoeuvres fail. In this article, we begin with a case study and review the literature around vagal manoeuvres.

QT Interval Dynamics and Cardiovascular Outcomes: A Cohort Study in an Integrated Health Care Delivery System

Background Long QT has been associated with ventricular dysrhythmias, cardiovascular disease (CVD) mortality, and sudden cardiac death. However, no studies to date have investigated the dynamics of within‐person QT change over time in relation to risk of incident CVD and all‐cause mortality in a real‐world setting. Methods and Results A cohort study among members of an integrated health care delivery system in Northern California including 61 455 people (mean age, 62 years; 60% women, 42% non‐White) with 3 or more ECGs (baseline in 2005–2009; mean±SD follow‐up time, 7.6±2.6 years). In fully adjusted models, tertile 3 versus tertile 1 of average QT corrected (using the Fridericia correction) was associated with cardiac arrest (hazard ratio [HR], 1.66), heart failure (HR, 1.62), ventricular dysrhythmias (HR, 1.56), all CVD (HR, 1.31), ischemic heart disease (HR, 1.28), total stroke (HR, 1.18), and all‐cause mortality (HR, 1.24). Tertile 3 versus tertile 2 of the QT corrected linear slope was associated with cardiac arrest (HR, 1.22), ventricular dysrhythmias (HR, 1.12), and all‐cause mortality (HR, 1.09). Tertile 3 versus tertile 1 of the QT corrected root mean squared error was associated with ventricular dysrhythmias (HR, 1.34), heart failure (HR, 1.28), all‐cause mortality (HR, 1.20), all CVD (HR, 1.14), total stroke (HR, 1.08), and ischemic heart disease (HR, 1.07). Conclusions Our results demonstrate improved predictive ability for CVD outcomes using longitudinal information from serial ECGs. Long‐term average QT corrected was more strongly associated with CVD outcomes than the linear slope or the root mean squared error. This new evidence is clinically relevant because ECGs are frequently used, noninvasive, and inexpensive.

Accidental Olanzapine Consumption in Children

Olanzapine is commonly used an atypical antipsychotic drug. Overdose is characterized by agitation, deep coma, blurred vision, myosis, respiratory depression and cardiovascular effects. Cardiovascular toxicity includes alterations in blood pressure, conduction disturbances like prolongation of the QRS/ QT intervals or ventricular dysrhythmias. We report two children with Olanzapine poisoning who presented with altered consciousness and one of them had ECG abnormality. Both of them recovered and discharged.

Impact of dextrose dose on hypoglycemia development following treatment of hyperkalemia

Background: Hyperkalemia is an electrolyte abnormality that may cause ventricular dysrhythmias and cardiac arrest. The presence of hyperkalemia may necessitate prompt treatment via intravenous insulin and dextrose. One notable complication of this therapy is the development of hypoglycemia. Previous trials have examined the impact of altering the insulin dose administered on hypoglycemia development; no trials to date however, have examined the impact of altering the dextrose dose. Methods: This was a multicenter, retrospective, matched cohort study of patients who received intravenous insulin and dextrose for reversal of hyperkalemia. Patients received either 25 g or 50 g of dextrose in addition to 10 units of insulin. Study populations were matched based on preexisting rates of acute kidney injury, end-stage renal disease, and diabetes mellitus. Blood glucose levels were measured at 60 and 240 min following treatment. Results: A total of 240 patients were included in the analysis. At 60 min following treatment, 15.8% of patients who received 25 g of dextrose developed hypoglycemia, as opposed to 8.3% of patients who received 50 g of dextrose ( p = 0.11). Hyperglycemia was more common in patients who received 50 g of dextrose at 60 min posttreatment; however, this difference did not persist at 240 min. Potassium reduction at 60 min did not differ between groups. In patients with a pretreatment blood glucose <110 mg/dl or without diabetes, rates of hypoglycemia were significantly lower when 50 g of dextrose was administered. Conclusion: In the overall patient population, use of 50 g of dextrose instead of 25 g does not reduce hypoglycemia incidence. However, it may be beneficial is select patient populations, such as patients without type 2 diabetes or patients with a baseline blood glucose <110 mg/dl. Administration of 50 g of dextrose did not appear to place patients at significant risk for hyperglycemia however and could be considered during treatment of hyperkalemia.