Magnesium sulfate has been used as an adjunct medication for the treatment of atrial fibrillation (AF) due to its ability to lessen sinus node depolarization via calcium antagonism. Prior studies investigating magnesium in rapid AF administered varying dosages, often targeted post-surgical patients, and had small sample sizes. Dr. Bryan Hayes summarized previous studies on Academic Life in Emergency Medicine in 2016, focusing on IV magnesium for rate-control in ED-related settings and concluded it to be safe and moderately effective for reducing heart rate in rapid AF.
A new 2018 study by Bouida and colleagues aimed to determine the benefit of two different magnesium doses vs. placebo to control ventricular rate in ED patients with AF, when used with an AV nodal blocking agent.
Subdissociative-dose ketamine (SDK) provides effective analgesia with lower rates of unwanted side effects when administered as a slow IV infusion. However, safety and efficacy studies have excluded geriatric patients until now, when Dr. Sergey Motov and colleagues strike again. SDK offers a much-needed pain management strategy for moderate to severe pain in this population who are often not ideal candidates for opioid analgesia.
Nitrofurantoin and fosfomycin are both recommended by the IDSA guidelines as first-line options in the treatment of uncomplicated cystitis due to their low resistance rates and minimal collateral damage. However, deciding which to choose is often based on convenience or habit, rather than supported by literature. This study was performed to compare sustained clinical resolution and microbiologic response between these two agents in middle-aged women with uncomplicated lower urinary tract infections.
Just like many other medications, ondansetron can prolong the QTc interval on an electrocardiogram. In fact, the FDA released a Drug Safety Communication in 2012 recommending against IV doses > 16 mg to help limit the risk. A prospective, observational study in 40 cardiac patients (heart failure or ACS) found that ondansetron 4 mg IV prolonged the QTc interval by 19 msec for up to 2 hours after the dose (Hafermann, Drug Healthc Patient Safety 2011). A retrospective cohort study of 210 ondansetron doses in pediatric ICU patients found that the QTC interval increased to 460-500 msec in 29% and to more than 500 msec in 11% (Trivedi, Pediatr Crit Care Med 2016). Underlying electrolyte abnormalities and organ dysfunction seemed to add the most risk.
But, what about in ED patients? What is the extent of QTC prolongation and is it clinically significant? Two groups have now published on this patient population. Here’s what they found.