Parenteral magnesium sulfate versus amiodarone in the therapy of atrial tachyarrhythmias: a prospective, randomized study.

OBJECTIVE: To compare the efficacy of parenteral magnesium sulfate vs. amiodarone in the therapy of atrial tachyarrhythmias in critically ill patients. DESIGN: Prospective, randomized study. SETTING: Multidisciplinary intensive care unit (ICU) at a university teaching hospital. PATIENTS: Forty-two patients, 21 medical and 21 surgical, of mean (SD) age 67 +/- 15 yrs and mean Acute Physiology and Chronic Health Evaluation II score of 22 +/- 6, with atrial tachyarrhythmias (ventricular response rate of > or = 120 beats/min) sustained for > or = 1 hr. INTERVENTIONS: After correction of the plasma potassium concentration to > or = 4.0 mmol/L, patients were randomly allocated to treatment with either a) magnesium sulfate 0.037 g/kg (37 mg/kg) bolus followed by 0.025 g/kg/hr (25 mg/kg/hr); or b) amiodarone 5 mg/kg bolus and 10 mg/kg/24-hr infusion. Therapeutic plasma magnesium concentration in the magnesium sulfate group was 1.4 to 2.0 mmol/L. Therapeutic end point was conversion to sinus rhythm over 24 hrs. MEASUREMENTS AND MAIN RESULTS: At study entry (time 0), initial mean ventricular response rate and systolic blood pressure were 151 +/- 16 (SD) beats/min and 127 +/- 30 mm Hg in the magnesium sulfate group vs. 153 +/- 23 beats/min and 123 +/- 23 mm Hg in the amiodarone group, respectively (p = .8 and .65). Plasma magnesium (time 0) was 0.84 +/- 0.20 vs. 1.02 +/- 0.22 mmol/L in the magnesium and amiodarone group, respectively (p = .1). Eight patients had chronic dysrhythmias (magnesium 3, amiodarone 5). Excluding the two patient deaths (amiodarone group, time 0 + 12 to 24 hrs), no significant change in systolic blood pressure subsequently occurred in either group. In the magnesium group, mean plasma magnesium concentrations were 1.48 +/- 0.36, 1.82 +/- 0.41, 2.16 +/- 0.45, and 1.92 +/- 0.49 mmol/L at time 0 + 1, 4, 12 and 24 hrs, respectively. By logistic regression, the probability of conversion to sinus rhythm was significantly better for magnesium than for amiodarone at time 0 + 4 (0.6 vs. 0.44), 12 (0.72 vs. 0.5), and 24 (0.78 vs. 0.5) hrs. In patients not converting to sinus rhythm, a significant decrease in ventricular response rate occurred at time 0 + to 0.5 hrs (mean decrease 19 beats/min, p = .0001), but there was no specific treatment effect between the magnesium and the amiodarone groups; thereafter, there was no significant reduction in ventricular response rate over time in either group. CONCLUSIONS: Intravenous magnesium sulfate is superior to amiodarone in the conversion of acute atrial tachyarrhythmias, while initial slowing of ventricular response rate in nonconverters appears equally efficacious with both agents.

Management of atrial tachyarrhythmias in the critically ill: a comparison of intravenous procainamide and amiodarone.

OBJECTIVE: To compare the efficacy and safety of intravenous (IV) amiodarone and procainamide for the treatment of atrial tachyarrhythmias (AT) in the critically ill. DESIGN: In this prospective study, patients were allocated to drug treatment on the basis of hospital identification number, even for procainamide and odd for amiodarone. SETTING: Patients were recruited from a teaching hospital ICU and did not include postoperative cardiac patients. PATIENTS AND PARTICIPANTS: 26 patients with AT sustained for at least 1 h and failure to respond to correction of possible precipitating factors were entered in the study. Exclusion criteria were systolic blood pressure (SBP) < 80 mmHg, and known hypersensitivity to either drug. Two patients with chronic atrial fibrillation (who received amiodarone) were later excluded from the analysis. In the final analysis, 14 patients received procainamide and 10 amiodarone. INTERVENTIONS: IV amiodarone (3 mg/kg followed by 10 mg/kg/24 h, with repeat dose of 3 mg/kg at 1 h if no response) or i.v. procainamide (10 mg/kg at 1 mg/kg/min followed by infusion of 2-4 mg/min for 24 h, with repeat dose of 5 mg/kg at 1 h if no response). MEASUREMENTS AND RESULTS: In the procainamide group 10/14 (71%) and in the amiodarone group 7/10 (70%) had converted to sinus rhythm by 12 h. There was no significant difference in response between the groups. SBP was not significantly different from baseline after administration of either drug. CONCLUSIONS: Procainamide and amiodarone appear to be safe and equally effective in the treatment of AT in the critically ill.

HIV, trauma, and infection control: universal precautions are universally ignored.

The medical, legal, and ethical problems associated with routine HIV screening have led to the recommendation that all patients should be presumed to be seropositive and thus protective measures should be taken by all health care workers. This philosophy, termed "universal precautions," has been difficult to adhere to or enforce, however. Nevertheless, in some trauma population subsets, the prevalence of HIV seropositivity runs as high as 19%, and thus presents an occupational hazard to the trauma health care worker. The mainstays of universal precautions (UP) are barrier techniques against body fluid contact and protection from inadvertent needlestick. To judge compliance with a strict UP protocol, surgical residents engaged in trauma room resuscitations were observed on a random basis by trauma nurse coordinators. Previously, UP had been discussed in conferences and by memo. Over 2 months, 81 trauma rooms were observed, involving 18 house officers. Overall, there was only 16% compliance with strict UP. The most common protocol variations involved sharps technique. While glove use was nearly universal, protective eye wear, ankle and foot protection, and body protection such as gowns or aprons were commonly ignored. Even in the presence of invasive procedures such as endotracheal intubation or insertion of chest tubes, compliance was less than 40%. The reasons most commonly given by house officers for the lapse in UP were not knowing the protocol, forgetting the protocol, or not having time to implement the protocol. Even for the nine patients residents identified as suspected of being in a high-risk category, UP was strictly adhered to only once. Compliance with universal precautions is difficult to achieve under the best of circumstances. It cannot be assumed that passive informational measures can achieve this goal. Active infection control surveillance and ongoing housestaff inservice are required to minimize the risk of inadvertent injury or contamination.

A high flow turbine CPAP system.

A continuous high flow CPAP system incorporating a turbine blower is described. The system achieves inspiratory flow rates of 150 l/min or more by means of reticulated gas flow and inspired oxygen fractions of 0.21-0.95. Positive airway pressure is provided by weighted disc valves and a modified aviation-type CPAP face mask provides electronic communication with the patient. The mobility of the system also enables its use as an intermittent physiotherapy aid. Work of breathing of the system, as assessed by total pressure fluctuations is at a minimum.