Friday, 23 October 2015

What's new in emergency medicine

GENERAL ADULT EMERGENCY MEDICINE
Modified Valsalva maneuver for treatment of hemodynamically stable supraventricular tachycardia (September 2015)
For both diagnostic and therapeutic purposes, the Valsalva maneuver is commonly used in patients with suspected supraventricular tachycardia (SVT). In a randomized trial of vagal maneuvers for the treatment of hemodynamically stable SVT, patients were assigned to perform the standard Valsalva maneuver (strain generating 40 mmHg pressure for 15 seconds while in a semirecumbent position) with or without supine repositioning and passive leg raise for 15 seconds following the strain phase [1]. Patients performing the modified Valsalva maneuver with supine repositioning and passive leg raise were significantly more likely to have restoration of sinus rhythm at one minute. For patients with hemodynamically stable SVT who are able to effectively perform the maneuver, we recommend the modified Valsalva maneuver as the initial treatment. (See "Atrioventricular nodal reentrant tachycardia", section on 'Stable patient'.)
Predictors of the need for repeat epinephrine doses in anaphylaxis (August 2015)
Epinephrine is the first-line therapy for anaphylaxis, and retrospective studies suggest that up to one-third of patients may require a second dose. However, predictive factors for requiring more than one dose are not well defined. In a prospective cohort study of over 500 patients (all ages) treated for anaphylaxis in a tertiary care emergency department, 14 percent of those requiring any epinephrine required more than one dose [2]. Patients with a history of previous anaphylaxis, and those presenting with flushing, diaphoresis, or dyspnea, were more likely to require multiple doses of epinephrine to control symptoms. Anaphylaxis is an inherently unpredictable disorder, but this study provides some insight into predictors of a more complicated treatment course and may help clinicians managing such patients. (See "Anaphylaxis: Rapid recognition and treatment", section on 'Dosing and administration'.)
Updated CDC guidelines on the management of sexually transmitted infections (June 2015)
The US Centers for Disease Control and Prevention (CDC) updated its guidelines on the management of sexually transmitted infections in June 2015 [3]. Major revisions include a lower threshold for the diagnosis of urethritis based on microscopy of a urethral specimen, a new emphasis on the role ofMycoplasma genitalium in persistent urethritis and cervicitis, preference for nucleic acid amplification-based testing for the diagnosis of Trichomonas vaginalis, and a recommendation to retest women after treatment for T. vaginalis to evaluate for reinfection. New screening recommendations include annual hepatitis C virus (HCV) testing for HIV-infected men who have sex with men and T. vaginalis testing for HIV-infected women annually and when pregnant. (See "Urethritis in adult men", section on 'Diagnostic criteria' and "Mycoplasma genitalium infection in men and women", section on 'Nongonococcal urethritis' and "Trichomoniasis", section on 'Follow-up' and "Primary care of the HIV-infected adult", section on 'Sexually transmitted infections'.)
Prevalence and clinical presentation of Borrelia miyamotoi infection (June 2015)
Borrelia miyamotoi is an emerging zoonotic pathogen that is transmitted by the same genus of ticks (eg, Ixodes scapularis, Ixodes pacificus) that transmitsBorrelia burgdorferi (the agent of Lyme disease), Anaplasma phagocytophilum, and Babesia species. In one case series, B. miyamotoi was identified using polymerase chain reaction (PCR) in approximately 1 percent of specimens from 11,515 patients in the northeastern United States who presented with an acute febrile episode from April through November in 2013 and 2014 [4]. Clinical information was available for 51 patients with B. miyamotoi infection; the majority had marked headache, myalgia, arthralgia, malaise, and/or fatigue, and 24 percent were hospitalized. Diagnostic testing is not widely available, but doxycycline, which is used to treat many other tick-borne infections, is also effective against B. miyamotoi. (See "Borrelia miyamotoi infection", section on 'Clinical manifestations'.)
Dabigatran reversal agent approved (June 2015)
Dabigatran is a direct oral anticoagulant used in patients with atrial fibrillation or venous thromboembolism. However, lack of a specific reversal agent has been a persistent concern. Idarucizumab, an experimental monoclonal antibody-based therapy, has now been demonstrated to reverse the effects of dabigatran. In a cohort of 90 elderly patients who had clinically significant bleeding or the need for an urgent invasive procedure while taking dabigatran for atrial fibrillation, idarucizumab caused rapid normalization of clotting times and/or surgical hemostasis [5]. There were five thrombotic events and 18 deaths; without a control group it is unclear how these would compare with outcomes in similar patients who did not receive idarucizumab. (See"Management of bleeding in patients receiving direct oral anticoagulants", section on 'Antidotes under development'.)
Oxygen not helpful in normoxic STEMI patients (June 2015)
Small studies have raised the possibility of harm from supplemental oxygen in patients with ST-elevation myocardial infarction (STEMI). In the AVOID study, 441 normoxic patients with confirmed STEMI were randomly assigned to either supplemental oxygen (8 L/min) or no oxygen [6]. The trial showed no improvement in the primary end point of a diminution in infarct size with oxygen and perhaps evidence of a larger infarct. For STEMI patients who are not hypoxic, we suggest not administering supplemental oxygen. (See "Overview of the acute management of ST elevation myocardial infarction", section on 'Oxygen'.)
Low allergic cross-reactivity between penicillins and carbapenems (May 2015)
Carbapenems (eg, imipenem, meropenem) share a common beta-lactam ring with penicillins and hence the potential for allergic cross-reactivity, and some drug information systems list penicillin allergy as a contraindication to the use of carbapenems (figure 1). In the largest study to date, 212 patients with allergy to penicillins, confirmed by skin testing, were then tested with carbapenems [7]. All subjects were negative to carbapenem skin testing and tolerated graded challenges to three different carbapenems. Based on this and other series, the rate of reactivity to carbapenems in patients with confirmed penicillin allergy is estimated at <1 percent. This supports our current recommendations on administration of carbapenems to patients reporting immediate-type penicillin allergy: Perform penicillin skin testing when available. If negative, patients may safely receive penicillins and carbapenems. If penicillin skin testing is positive or not available, carbapenems may be administered via a graded challenge. (See "Penicillin-allergic patients: Use of cephalosporins, carbapenems, and monobactams", section on 'Carbapenems'.)
High-flow oxygen therapy by nasal cannula for acute hypoxemic respiratory failure in adults (May 2015)
In adults with acute hypoxemic respiratory failure without hypercapnia, high-flow oxygen therapy by nasal cannula is a reasonable alternative to standard oxygen therapy or noninvasive positive pressure ventilation. Such patients should be managed in settings with appropriate monitoring (eg, emergency departments or intensive care units). In a multicenter trial of 310 adults with hypoxemic respiratory failure without hypercapnia that compared high-flow oxygen therapy by nasal cannula with standard oxygen therapy by face mask or noninvasive positive pressure ventilation (NPPV), the intubation rate was not significantly different for patients receiving high-flow oxygen compared with standard therapy or NPPV [8]. Patients who received high-flow oxygen therapy had significantly lower 90-day mortality and fewer days of mechanical ventilation than the other two groups, although patients receiving NPPV might have had a greater degree of baseline lung injury. (See "Continuous oxygen delivery systems for infants, children, and adults", section on 'High flow'.)
New practice guideline for unprovoked first seizures in adults (April 2015)
The American Academy of Neurology and the American Epilepsy Society have released a new guideline on the management of an unprovoked first seizure in adults, with a particular focus on the decision of whether or not to start antiepileptic drug (AED) therapy at the time of the initial seizure [9]. Unprovoked seizures include seizures of unknown etiology as well as those related to a preexisting brain lesion or progressive nervous system disorder. The guideline advocates for an individualized approach that weighs the risk of seizure recurrence against the adverse effects of AEDs and incorporates patient values and preferences. The most important risk factors for seizure recurrence after an unprovoked first seizure are clinical or radiographic evidence of prior brain insult or injury, epileptiform abnormalities on electroencephalogram, and nocturnal seizure. (See "Initial treatment of epilepsy in adults", section on 'First-time unprovoked seizure'.)
GENERAL PEDIATRIC EMERGENCY MEDICINE
Diagnostic accuracy of serial ultrasounds for pediatric appendicitis (April 2015)
In pediatric patients whose initial ultrasound is equivocal for the diagnosis of appendicitis and who have persistent findings, repeat physical examination and a second ultrasound has good diagnostic accuracy and can markedly reduce the use of computed tomography (CT). A prospective observational study of 294 children undergoing acute evaluation for abdominal pain (38 percent with appendicitis) evaluated a protocol stratifying children into three paths: serial physical examination, surgical consultation, and repeat ultrasound if the initial ultrasound was equivocal; discharge home if the initial ultrasound showed a normal appendix; and surgical consultation if the initial ultrasound was positive for appendicitis [10]. This strategy, consistent with our approach, achieved a sensitivity of 97 percent and a specificity of 91 percent; CT was performed in four patients. (See "Acute appendicitis in children: Diagnostic imaging", section on 'Imaging approach'.)
PEDIATRIC RESUSCITATION
Timely administration of epinephrine improves survival following pediatric arrest (August 2015)
Epinephrine is recommended during cardiopulmonary resuscitation for children with asystole or pulseless electrical activity without ventricular fibrillation or tachycardia. In a retrospective review of registry data on 1558 children with inpatient arrest and a documented nonshockable initial rhythm, adjusted survival to discharge occurred in up to 37 percent of patients who received epinephrine one minute or less after arrest and decreased 5 percent for every additional minute delay in epinephrine administration [11]. Survival with favorable neurologic outcome at discharge occurred in approximately 16 percent of all patients and in adjusted analysis also decreased 5 percent for every additional minute of delay in epinephrine administration. Thus, timely administration of epinephrine is associated with improved outcomes after pediatric arrests with nonshockable cardiac rhythms. (See "Guidelines for pediatric advanced life support", section on 'Advanced management'.)
Oxyhemoglobin desaturation during rapid sequence intubation in children (June 2015)
Timing the laryngoscopy duration during a pediatric endotracheal intubation attempt and discontinuing it if intubation is unsuccessful within a specific time period (eg, 30 seconds) may prevent oxyhemoglobin desaturation. In an observational study that used video review of 114 children undergoing rapid sequence intubation in a pediatric emergency department, at least one episode of oxyhemoglobin desaturation (pulse oximetry <90 percent) occurred in 33 percent of patients [12]. Oxyhemoglobin desaturation was more common in children two years of age or younger compared with older children (59 versus 10 percent) and was strongly associated with the duration of laryngoscopy; 82 percent of patients experiencing desaturations had laryngoscopy durations of 30 seconds or longer. There was no association between the number of intubation attempts and episodes of desaturation. (See "Emergency endotracheal intubation in children", section on 'During laryngoscopy/intubation'.)
Post-resuscitation therapeutic hypothermia not better than targeted normothermia in children (May 2015)
Therapeutic hypothermia to maintain core body temperature below normal (typically 32 to 34°C) has been proposed after resuscitation from pediatric cardiac arrest based upon evidence for improved neurologic outcome in neonates and selected adults. In a multicenter trial involving children who were resuscitated from an out-of-hospital cardiac arrest, 260 patients (48 hours to 18 years of age) were randomized to either therapeutic hypothermia with a target core body temperature of 33°C or therapeutic normothermia to maintain a temperature of 36.8°C. One-year survival with good neurologic function was not significantly different in patients undergoing therapeutic hypothermia compared with therapeutic normothermia (20 versus 12 percent, respectively, relative likelihood 1.54, 95% CI 0.86-2.76) [13]. Of note, the number of patients randomized was insufficient to exclude an important benefit or harm from therapeutic hypothermia. Further study is needed to determine the role of therapeutic hypothermia after resuscitation from pediatric cardiac arrest; current practice is to provide targeted temperature management to prevent fever (core body temperature >38°C). (See "Guidelines for pediatric advanced life support", section on 'Early postresuscitation management'.)
PRIMARY CARE ORTHOPEDICS AND SPORTS MEDICINE
Rehabilitation exercises for chronic tendinopathy (August 2015)
For a number of years, rehabilitation programs for the treatment of chronic, overuse tendinopathies have emphasized the eccentric phase of resistance exercises. However, recent studies suggest that resistance exercises involving the affected tendon may be effective regardless of what phase is emphasized. In a single-blinded randomized trial involving 58 patients with chronic Achilles tendinopathy, heavy slow resistance training emphasizing both the concentric and eccentric portions of the exercises selected produced the same improvements in symptoms, function, and tissue appearance on ultrasound achieved by patients following a training program that emphasized only the eccentric portion of selected exercises [14]. The improvements were sustained at one-year follow-up in each group. Of note, patient compliance was significantly better among patients following the heavy slow resistance program (92 versus 78 percent in the eccentric training group). (See "Achilles tendinopathy and tendon rupture", section on 'Heavy slow resistance training'.)
Platelet-rich plasma for acute muscle injury (July 2015)
Platelet-rich plasma (PRP) injections have been touted as an effective treatment for acute muscle and tendon injuries despite scant evidence from randomized trials. The results of a recent randomized trial of 90 professional athletes with acute, MRI-confirmed hamstring injury cast further doubt on the effectiveness of PRP. In this trial, athletes treated with a single PRP injection in addition to intensive physical therapy did not return to play any faster than athletes treated with intensive physical therapy alone [15]. Re-injury rates were also similar. (See "Hamstring muscle and tendon injuries", section on 'PRP and other injections'.)
PROCEDURES
Chlorhexidine-alcohol for site preparation before intravascular catheter insertion (October 2015)
Skin antiseptic preparation with chlorhexidine-alcohol prior to intravascular catheter insertion provides greater protection against short-term catheter-related infection than povidone iodine-alcohol. In a large randomized trial including 2349 patients (5159 catheters), use of chlorhexidine–alcohol resulted in a lower incidence of catheter-related infections than povidone iodine-alcohol (0.28 versus 1.77 per 1000 catheter-days) [16]. We continue to recommend use of chlorhexidine-alcohol prior to catheter insertion, in conjunction with other measures for prevention of intravascular catheter-related infections. (See"Prevention of intravascular catheter-related infections", section on 'Insertion site preparation'.)
TRAUMA
Lower mortality for children treated in pediatric trauma centers (October 2015)
In a retrospective analysis of a national database of almost 176,000 pediatric trauma patients, the unadjusted mortality rate was lowest among patients treated in pediatric trauma centers (0.6 percent) compared with adult trauma centers (2.3 percent) and mixed trauma centers (1.8 percent) [17]. After adjustment, children treated in adult or mixed trauma centers had an estimated 57 and 45 percent increased risk of dying, respectively, when compared with patients treated in pediatric trauma centers (PTC). Because optimal outcomes occur when the critically injured child is initially resuscitated and subsequently managed in a PTC, it is preferable to provide care in such facilities from the outset, whenever possible, or to arrange transfer to a PTC for ongoing management. (See "Trauma management: Approach to the unstable child", section on 'Definitive care'.)
Contrast regimens for children requiring abdominal and pelvic computed tomography after blunt trauma (September 2015)
In a multicenter, prospective observational study of over 5000 children with blunt trauma undergoing abdominal and pelvic computed tomography (CT) with intravenous (IV) contrast, of whom 1010 also received oral contrast, the sensitivity for identifying intraabdominal injury was not significantly different with or without oral contrast (99 versus 98 percent, respectively) [18]. Patients who received oral contrast had a significantly longer delay in undergoing CT (median 12 minutes) compared with children who received IV contrast alone. Thus, oral contrast does not improve detection of intraabdominal injury in children but delays time to imaging. We suggest that hemodynamically stable children undergoing CT of the abdomen and pelvis after blunt trauma receive IV contrast alone rather than IV and oral contrast.  (See "Overview of blunt abdominal trauma in children", section on 'Use of contrast'.)
Risk of intracranial injury in young children with isolated linear skull fractures (April 2015)
Linear skull fractures account for approximately 75 percent of all skull fractures in children, and hospitalization for this condition is frequently performed. In a prospective, multicenter observational study of 350 children (median age 10 months) with isolated linear skull fractures and no additional injury identified on initial computed tomography, no patient required neurosurgical intervention on follow-up ranging from 7 to 90 days (95% CI 0 to 1 percent), although 201 patients were hospitalized after initial evaluation [19]. These findings suggest that neurologically normal children with isolated linear skull fractures have a low risk for intracranial injury requiring neurosurgical intervention and may safely undergo discharge home to a reliable caretaker after emergency department evaluation. (See "Skull fractures in children", section on 'Isolated skull fractures'.)
Imaging to rule out ligamentous cervical spine injury in the unconscious patient (April 2015)
Debate continues about the best method to rule out ligamentous cervical spine injury in the unconscious trauma patient. Two systematic reviews of more recent, higher-quality studies support the use of advanced multi-detector computed tomography (MDCT) alone (ie, without additional magnetic resonance imaging [MRI] studies) for this purpose. One systematic review performed by the Eastern Association for the Surgery of Trauma (EAST) included five studies that used axial CT slices of less than 3 mm to assess obtunded adult trauma patients (follow-up was completed for 1017 patients), and no unstable injuries were missed [20]. Another review included a separate analysis of seven higher-quality studies, defined by their prospective design, low risk of bias, and use of more sophisticated CT imaging and interpretation, involving 1686 patients and reported no missed cervical spine injuries of clinical significance [21]. While we continue to prefer MRI to rule out ligamentous injury in such patients, properly performed and interpreted MDCT appears to be a viable alternative in some settings. (See "Evaluation and acute management of cervical spinal column injuries in adults", section on 'Approach to imaging'.)
Imaging of potential thoracolumbar injury (April 2015)
In contrast to cervical spine trauma, thoracolumbar (TL) injuries are studied relatively infrequently, and well-defined decision rules for obtaining imaging studies of such injuries are lacking. Recently, a prospective study performed at 13 trauma centers in the United States proposed a decision-rule for imaging potential TL injuries [22]. The study included 499 patients diagnosed with TL injuries, 264 of whom required treatment (surgical management in 29.2 percent and rigid spine immobilization (TL spine orthosis, TLSO) in 70.8 percent). Injuries were identified by multidetector computed tomography in most instances (93.3 percent). According to the study, the presence of three major risk factors (suggestive examination findings, high-risk mechanism of injury, and age over 60) predicted a clinically significant injury with a sensitivity of 98.9 percent and a specificity of 29 percent, and predicted the need for surgery with a sensitivity of 100 percent and a specificity of 27.3 percent. While an important step forward, this decision rule omits some important indications for imaging (eg, presence of a cervical spine injury) and needs further prospective validation. (See "Evaluation of thoracic and lumbar spinal column injury", section on 'Decision rules for imaging thoracic or lumbar spine injury'.)

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