Adenosine in the termination of albuterol-induced supraventricular tachycardia

Five percent of children in the United States have asthma. Status asthmaticus is one of the most common conditions for which children seek care in a pediatric emergency department. beta 2-Agonists such as albuterol are the mainstay of emergency therapy for such children. We present a case of a 4-year-old boy who experienced supraventricular tachycardia (SVT) following albuterol therapy. This is believed to be the first report of adenosine being successfully used to treat a child with albuterol-induced SVT. We also briefly review the recognition and management of SVT in children and the pharmacokinetics of and indications for adenosine.     

Electrophysiological mechanisms and determinants of vagal maneuvers for termination of paroxysmal supraventricular tachycardia

BACKGROUND: The vagal maneuvers used for termination of paroxysmal supraventricular reentrant tachycardia (PSVT) appear to involve more complex mechanisms than we have known, and further study should be done to explore the possible mechanisms. METHODS AND RESULTS: In this study, 133 patients with PSVT and 30 age- and sex-matched control subjects were included. We assessed the effects of different vagal maneuvers on termination of PSVT and compared baroreflex sensitivity and beta-adrenergic sensitivity between the patients with PSVT and control subjects. Out of 85 patients with atrioventricular reciprocating tachycardia (AVRT), vagal maneuvers terminated in 45 (53%). Of these, 28 (33%) terminated in the antegrade limb and 17 (20%) terminated in the retrograde limb. Out of 48 patients with atrioventricular nodal reentrant tachycardia (AVNRT), vagal maneuvers terminated the tachycardia in the antegrade slow pathway (14%) or in the retrograde fast pathway (19%). Baroreflex sensitivity was poorer but isoproterenol sensitivity test better in patients with AVNRT. Poorer antegrade atrioventricular node conduction properties and better vagal response determined successful antegrade termination of AVRT by vagal maneuvers. Poorer retrograde accessory pathway conduction property but better vagal response determined successful retrograde termination of AVRT. Better sympathetic and vagal response associated with poorer retrograde atrioventricular node conduction determined retrograde termination of AVNRT by the Valsalva maneuver. CONCLUSIONS: Both the vagal response and conduction properties of the reentrant circuit determine the tachycardia termination by vagal maneuvers. Improved understanding of the interaction of autonomic and electrophysiological mechanisms in maintaining or terminating PSVT may provide important insight into the pathophysiology of these two tachycardias.     

The use of propofol for sedation in the emergency department

Coats' disease is an idiopathic, primary vascular anomaly of the retina often presenting with retinal detachment. In this report, the unusual radiologic findings of a 17-month-old patient with advanced Coats' disease are discussed. Computed tomography (CT) showed diffuse increased density of the right eye. Magnetic resonance imaging (MRI) demonstrated moderately hyperintense signal intensity on T1-weighted images, mildly hypointense signal intensity on T2-weighted images, and linear enhancement of the leaves of the detached retina with intense enhancement in the retinal periphery following gadolinium-diethylenetriamine penta-acetic acid (DTPA) contrast administration. The hypointense T2-weighted images and the linear enhancement of the detached retina have not been reported previously in cases of Coats' disease. These observations correlated with the histopathologic features, which showed a totally detached retina containing large telangiectatic vesses and a supretinal space occupied by eoinophilic proteinaceous exudates containing abundant cholesterol crystals. It appears that the MRI characteristics observed in Coats' disease may vary depending on the nature of the subretinal exudate and the severity of the disease.     

The use of noninvasive positive pressure ventilation in the emergency department: results of a randomized clinical trial

OBJECTIVE: To determine whether the use of noninvasive positive pressure ventilation (NPPV) in the emergency department (ED) will reduce the need for tracheal intubation and mechanical ventilation. DESIGN: Randomized, controlled, prospective clinical trial. SETTING: ED of Barnes-Jewish Hospital, a university-affiliated teaching hospital. PATIENTS: Twenty-seven patients meeting a predetermined definition of acute respiratory distress requiring hospital admission. INTERVENTIONS: Conventional medical therapy for the various etiologies of acute respiratory distress and the application of NPPV. MEASUREMENTS AND RESULTS: The primary outcome measure was the need for tracheal intubation and mechanical ventilation. Secondary outcomes also assessed included hospital mortality, hospital length of stay, acquired organ system derangements, and the utilization of respiratory care personnel. Sixteen patients (59.3%) were randomly assigned to receive conventional medical therapy plus NPPV, and 11 patients (40.7%) were randomly assigned to receive conventional medical therapy without NPPV. The two groups were similar at the time of randomization in the ED with regard to demographic characteristics, hospital admission diagnoses, and severity of illness. Tracheal intubation and mechanical ventilation was required in seven patients (43.8%) receiving conventional medical therapy plus NPPV and in five patients (45.5%) receiving conventional medical therapy alone (relative risk=0.96; 95% confidence interval=0.41 to 2.26; p=0.930). There was a trend towards a greater hospital mortality rate among patients in the NPPV group (25%) compared to patients in the conventional medical therapy group (0.0%) (p=0.123). Among patients who subsequently required mechanical ventilation, those in the NPPV group had a longer time interval from ED arrival to the start of mechanical ventilation compared to patients in the conventional medical therapy group (26.0+/-27.0 h vs 4.8+/-6.9 h; p=0.055). CONCLUSIONS: We conclude that the application of NPPV in the ED may delay tracheal intubation and the initiation of mechanical ventilation in some patients with acute respiratory distress. We also demonstrated that the application of NPPV was associated with an increased hospital mortality rate. Based on these preliminary observations, larger clinical investigations are required to determine if adverse patient outcomes can be attributed to the early application of NPPV in the ED. Additionally, improved patient selection criteria for the optimal administration of NPPV in the ED need to be developed.     

Prospective use of glycoprotein IIb/IIIa receptor blockers in the emergency department setting

OBJECTIVE: We examined whether alcohol consumption and problem drinking decreased with age or if the reported declines were actually cohort and/or period effects. METHOD: We utilized data from the Normative Aging Study, assessing 1,267 men three times over an 18-year period (1973, 1982, 1991). Men were divided into five 9-year birth cohorts; age ranged from 46 to 72. RESULTS: Sequential analyses using repeated measures ANOVAs showed significant age, cohort and period effects. Although there was a tendency for alcohol consumption to decline with age, this was not true for all cohorts. Men born between 1910 and 1918 increased from an average of 350 to 440 drinks per year from their fifties to their sixties. The younger cohorts tended to report both more consumption and more problems. However, period had the most consistent effect in this study. There was an increase in problems and in consumption during the 1970s but a decrease in the 1980s, with the exception of the youngest cohort (1937-1945) who reported more problems in the 1991 assessment despite lower consumption. CONCLUSIONS: Age-related change in both consumption and problems varied depending upon which cohort or time period was assessed. Thus, drinking patterns are a complex amalgam of individual aging and societal change.     

Safety and efficacy of central intravenous bolus administration of adenosine for termination of supraventricular tachycardia

OBJECTIVES: This study was done to quantify the dosing differences between central and peripheral adenosine administration for treatment of supraventricular tachycardia. BACKGROUND: Earlier studies that evaluated the safety and efficacy of adenosine primarily utilized a peripheral site of administration. Although it has been recommended that lower doses should be given centrally, dosing recommendations have not been provided. METHODS: Thirty adults with supraventricular tachycardia underwent invasive electrophysiologic study and were treated with central and peripheral intravenous administration of adenosine. Peripheral injections were administered through a venous catheter in an upper extremity and central infusions were accomplished by means of a catheter positioned in or near the right atrium. The site of administration was randomized and each subject received adenosine by both routes. Adenosine was administered every minute in increasing increments of 3, 6, 9 and 12 mg until the tachycardia terminated. Peripheral responses were compared with those obtained centrally. RESULTS: The minimal effective peripheral dose was distributed among the four doses: Tachycardia was terminated in 11 patients with 3 mg (37%), in 10 (33%) with 6 mg, in 4 (13%) with 9 mg and in 5 (17%) with 12 mg. In contrast, after central administration, 23 episodes of tachycardia (77%) were terminated with 3 mg, 6 (20%) with 6 mg and 1 (3%) with 9 mg; none required 12 mg. Lower doses of adenosine were more effective after central than after peripheral administration, with 63% of the subjects requiring a lesser dose. There was no difference between the two routes of drug administration in the incidence of side effects or transient arrhythmias at the time of tachycardia termination. CONCLUSIONS: Adenosine can be safely given centrally for termination of supraventricular tachycardia. The initial dose should be 3 mg.     

Prospective use of platelet glycoprotein IIb/IIIa receptor blockers in the emergency department setting

Platelets play a pivotal role in the pathophysiology of acute coronary syndromes (ACS) and thus are logical therapeutic targets for treatment of this disease process. Platelet glycoprotein (GP IIb/IIIa receptor antagonists, which interrupt the final common pathway of platelet aggregation, have been proven to reduce the 30-day incidence of death, acute myocardial infarction (MI), and urgent revascularization in both high-risk and low-risk patients undergoing percutaneous intervention procedures. Three-year follow-up has indicated that these benefits appear durable. Recent large-scale randomized trials have demonstrated the value of GP IIb/IIIa receptor inhibitors in reducing the risk of death and MI in unstable angina/non-Q-wave MI patients receiving pharmacologic management. And, emerging evidence suggests a future role for GP IIb/IIIa receptor inhibitors as an adjunct to low-dose fibrinolytic therapy in patients with acute MI. As the list of indications for GP IIb/IIIa receptor antagonists expands to encompass the full spectrum of ACS, there is increasing interest in the potential use of these agents in the emergency department setting. The integration of GP IIb/IIIa receptor inhibitors into emergency department protocols will ultimately depend largely on whether these drugs prove to be safe and effective regardless of the direction of ST-segment deviation, and irrespective of whether definitive therapy will be invasive or conservative.     

Influence of beta-adrenergic and vagal activity on the effect of exogenous adenosine on supraventricular tachycardia termination

Adenosine, which binds to cell surface receptors and couples with guanosine triphosphate-binding inhibitory proteins (G(i)), is potent in terminating supraventricular tachycardia (SVT). However, whether the differences in autonomic tone will influence this effect remains unknown. This study was designed to investigate the role of beta-adrenergic and vagal activity on the action of adenosine. Forty patients with clinically documented SVT (22 with atrioventricular node reentrant tachycardia and 18 with atrioventricular reciprocating tachycardia) were divided into 4 groups with 10 patients in each group. In groups 1 and 2, adenosine was intravenously injected during the baseline state and during infusion of isoproterenol (2 and 4 microg/min, respectively). Group 2 patients received atropine (0.04 mg/kg) injection before isoproterenol infusion. In groups 3 and 4, intravenous injection of adenosine was given during the baseline state and after injection of atropine (0.02 and 0.04 mg/kg, respectively). Group 4 patients received propranolol (0.2 mg/kg) before atropine injection. The minimal dose of adenosine to terminate tachycardia during isoproterenol infusion of 2 microg/min was greater than that during the baseline state in both groups 1 and 2. The minimal dose of adenosine during isoproterenol infusion with 4 microg/min was higher than that with 2 microg/min in group 2, but not in group 1 patients. In both groups 3 and 4, the minimal dose of adenosine required to terminate tachycardia during atropine injection with 0.02 mg/kg was greater than that during the baseline state. The minimal effective dose of adenosine during atropine injection with 0.04 mg/kg was higher than that with 0.02 mg/kg in group 4, but not in group 3 patients. In conclusion, either limb of the autonomic nervous system may modulate the adenosine dosage required for termination of SVT. Patients taking drugs such as beta blockers or vagolytic agents may need alterations in the dose of adenosine for therapy.     

The hemodynamic effects of induced supraventricular tachycardia in man

The circulatory effects of supraventricular tachycardia (SVT) were studied in eight patients who reported disabling symptoms during paroxysms of the arrhythmia. Supraventricular tachycardia was induced in each patient by rapid atrial pacing or with atrial premature stimuli. Hemodynamic parameters in sinus rhythm and following the initiation of SVT were recorded and compared. The following mean values were observed in sinus rhythm (SR) and SVT. Heart rate (beats/min): SR 79, SVT 183; P-R interval (msec): during SR, 154; during SVT, 256; ratio of mean P-R intervals to mean R-R cycl lengths: SR 20%, SVT 76%; brachial artery pressures (mmHg): SR 141, SVT 99; cardiac index (L/min/m2): SR 3.6, SVT 2.2; pulmonary artery pressures (mmHg): SR 18/7, SVT 26/15; peak right atrial pressures (mm Hg): SR 4, SVT 17. Large waves appeared in the right atrium during SVT due to atrial contraction against closed tricuspid valves. Pulsus alternans were observed in each case during SVT. Despite the presence of chest pain during SVT, the coronary arteries were normally patent in four patients who underwent coronary arteriography.     

Is myoglobin useful in the diagnosis of acute myocardial infarction in the emergency department setting?

The authors evaluated the usefulness of a rapid fluorometric enzyme immunoassay for myoglobin (Myo) for early diagnosis of acute myocardial infarction (AMI) in patients in the emergency department. The rapid fluorometric enzyme immunoassay for myoglobin was performed on timed blood samples collected previously for serial CK and CKMB determinations from 41 patients who initially presented to the ED with chest pain and were subsequently admitted to patient care units. Twenty-two patients were AMI positive and 19 were AMI negative. In 12 patients who were AMI positive, Myo increased rapidly and significantly peaking at 6.53 +/- 5.45 hours, whereas in the other 10 patients who were AMI positive, only the declining slopes of Myo were observed due to late AMI presentation. In the AMI negative group, Myo values were within reference range in 8 and persistently elevated in 11. Using the initial rate of Myo release of 20 ng/mL per hour as criteria of discrimination, this assay has a sensitivity of 90.1% and a specificity of 74%. Available samples for the two patients who were false negative were past the window of Myo release for AMI detection. All five patients who were false positive were associated with various degrees of muscular trauma or renal disorder. The authors conclude that the initial rate of Myo release demonstrates good utility both at early detection and early exclusion of AMI. However, its tissue nonspecificity may not permit AMI recognition in the presence of muscular injury.     

The intubating laryngeal mask: use of a new ventilating-intubating device in the emergency department

OBJECTIVE: Despite modern diagnostic methods and appropriate treatment, pleural empyema remains a serious problem. Our purpose was to assess the feasibility and efficacy of the video-assisted thoracoscopic surgery in the management of nontuberculous fibrinopurulent pleural empyema after chest tube drainage treatment had failed to achieve the proper results. METHODS: We present a prospective selected single institution series including 45 patients with pleural empyema who underwent an operation between March 1993 and December 1996. Mean preoperative length of conservative management was 37 days (range, 8-82 days). All patients were assessed by chest computed tomography and ultrasonography and underwent video-assisted thoracoscopic debridement of the empyema and postoperative irrigation of the pleural cavity. RESULTS: In 37 patients (82%), video-assisted thoracoscopic debridement was successful. In 8 cases, decortication by standard thoracotomy was necessary. There were no complications during video-assisted thoracic operations. The mean duration of chest tube drainage was 7. 1 days (range, 4-140 days). At follow-up (n = 35) with pulmonary function tests, 86% of the patients treated by video-assisted thoracic operation showed normal values; 14% had a moderate obstruction and restriction without impairment of exercise capacity, and no relapse of empyema was observed. CONCLUSIONS: Video-assisted thoracoscopic debridement represents a suitable treatment for fibrinopurulent empyema when chest tube drainage and fibrinolytics have failed to achieve the proper results. In an early organizing phase, indication for video-assisted thoracic operation should be considered in due time to ensure a definitive therapy with a minimally invasive intervention. For pleural empyema in a later organizing phase, full thoracotomy with decortication remains the treatment of choice.     

Interpreter use in an inner city accident and emergency department

OBJECTIVE: To determine the extent of communication problems that arose from patients whose primary language was non-English presenting to an inner city accident and emergency (A&E) department. METHODS: A prospective survey over seven consecutive days during September 1995. All adult patients other than those directly referred by their general practitioner to an inpatient team had a questionnaire completed by the A&E doctor first seeing the patient. The doctor recorded language ability and form of interpreter used, and estimated any prolongation of the consultation and ability to improve communication by the use of additional services. RESULTS: 103 patients (17%) did not speak English as their primary language; 55 patients (9.1% of the study population) had an English language ability rated as other than good, and 16 (29%) of these consultations could have been improved by the use of additional interpreter services; 28 patients overall (4.6% of the study population) required the use of an interpreter, who was usually a relative. CONCLUSIONS: A significant number of patients presenting to A&E have difficulty in communicating in English. These consultations could often have been improved by the use of additional interpreter services. Telephone interpreter services may provide the answer for use in A&E departments because of their instant and 24 hour availability.     

A protocol to improve analgesia use in the accident and emergency department

In this experiment, intracellular K+ concentration ([K+]i) and ATPase activity of myocardiocytes were measured in early stage of burn injury. Comparing with control group, it was found that, 1. [K+]i were decreased after burn injury, [K+]i of 1st, 3rd, 8th and 24th hours were decreased to 96.2 +/- 1.3%, 85.8 +/- 1.3%, 65.9 +/- 1.0% and 73.7 +/- 1.1% of normal, respectively. 2. Cardiac sarcolemma total ATPase, Mg(2+)-ATPase and Na(+)-K(+)-ATPase activities were all reduced significantly at 8th hour after injury. These results suggest that, burn injury accelerates K+ efflux current, but inhibits K+ influx current, and the reduction of Na(+)-K(+)-ATPase activity is one reason of decrease of [K+]i after injury.