May 10, 2021

Background: Occlusion myocardial infarction (OMI) is defined as acute coronary occlusion or near occlusion with insufficient collateral circulation leading to downstream myocardial infarction. Currently, we use STEMI ECG criteria to identify acute coronary OMI in the clinical setting. The diagnosis of STEMI is based on millimeter criteria on the ECG (see below) and essentially acts as a surrogate marker for the presence of an OMI. Under the current STEMI vs NSTEMI paradigm, almost 1/3rd of NSTEMI patients have unrecognized acute total occlusion (OMI) discovered on delayed angiograms. The delay in diagnosis results in increased short and long-term mortality compared to NSTEMI patients without OMI (We have reviewed these trials before on REBEL EM). As ECG interpretation has improved it has become clear that there are other early ECG indicators of OMI that do not meet STEMI criteria (i.e. hyperacute T-waves) that would benefit from early percutaneous coronary intervention [2].  Additionally, there are other features such as hemodynamic instability and persistent symptoms, as well as adjunct modalities, like echocardiography, that can add useful information and increase the likelihood of OMI. Ultimately, the OMI paradigm emphasizes underlying pathology over surrogate test results (i.e. STEMI).

May 6, 2021

Background: Hyponatremia is one of the most common electrolyte abnormalities seen in clinical practice. Under-correction could lead to cerebral edema, whereas overcorrection could result in osmotic demyelination syndrome (ODS).  The current recommendation is to use hypertonic saline in small, fixed, intermittent boluses. This approach avoids rapid partial correction of serum sodium, limits risk of overcorrection, and doesn’t require complex calculations. Slow continuous infusions on the other hand, require complex calculations to adjust hypertonic saline infusions to a rate of correction over time based on the rate of serum sodium correction.  Despite these facts, there are limited high-quality trials that have demonstrated if slow continuous infusion (SCI) therapy is as good as or as safe as rapid intermittent bolus (RIB) therapy.

May 1, 2021

Background: Head up (HUP) CPR is an emerging concept.  The theory behind HUP is it allows for venous blood to drain from the brain to the heart thereby decreasing intracranial pressure and lowering the arterial/venous pressure waves which concuss the brain with each compression.  Additionally, conventional CPR increases vascular pressure in both the venous and arterial sides of the heart simultaneously which in turn increases intrathoracic and intracranial pressure which can impede cerebral blood flow and compromise coronary circulation.  All of these theories were evaluated and confirmed in animal models with very limited human trials. In order for HUP to work however, we have to be able to effectively pump blood up to the brain which is not typically achieved with conventional CPR (C-CPR). Active Compression Decompression with Impedance Threshold Devices (ACD-ITD) are one way to improve C-CPR.  They can theoretically help by reducing intracranial pressure (ICP), reduce the potential for concussion with every compression, increase cerebral perfusion pressure (CerPP) and coronary perfusion pressure (CorPP). However, with any new approach, we should always temper enthusiasm, as the realities of implementing them may actually not be helpful, and maybe even harmful.

April 28, 2021

Background: It has long been thought that intravenous contrast can lead to acute kidney injury. Recent data, however, has called this dogmatic teaching into question.  Unfortunately, the data arguing against the association of contrast with AKI comes from observational trials and, thus, carry with it numerous biases.  One potential bias is baseline differences in the risk between exposure groups with patients not receiving contrast perceived to be at higher risk and those receiving contrast at lower risk of PC-AKI. Another example is selection bias due to requiring subsequent renal function testing in patients deemed to be higher risk and not those at lower risk.  Both of these can form a control group at high risk of kidney injury which creates a bias in favor of contrast and potentially masking harm.

April 15, 2021

Background: In patients requiring mechanical ventilation, sedative medications are used for patient comfort and safety.  However, these medications can also lead to brain dysfunction (i.e. delirium or coma) and long-term cognitive impairment. Currently, the Society of Critical Are Medicine [2] recommends sedation with either dexmedetomidine or propofol targeted to light levels of sedation in adult patients receiving mechanical ventilation. The evidence for which agent to use thus far with respect to acute brain dysfunction or cognitive impairment after critical illness have been unclear in determining which agent should be used. In fact, the Society of Critical Care Medicine’s 2018 Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU (PADIS Guidelines) recommends the use of either propofol or dexmedetomidine to target light sedation.
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