Diagnosis, not energy or weight, determines ventricular defibrillation.

In a study demonstrating 95% success in achieving defibrillation in 94 resuscitative events in adult patients, the authors find that weight did not determine that success and that the results were obtained at significantly low rates of energy output. Diagnosis was the key, they conclude, and they view the expensive high-energy defibrillators marketed today as unnecessary, potentially lethal, and economically wasteful.

Free plasma DNA in patients with pulmonary embolism.

Plasma samples from 46 patients with suspected pulmonary embolism and 25 patients with suspected acute myocardial infarction were analyzed for DNA by counterimmunoelectrophoresis (CIE). Anti-DNA serum was obtained from a patient with systemic lupus erythematosus who had a high titer of anti-DNA antibodies. Seven of eight patients (88%) with high probability of pulmonary embolism by lung scan criteria had free DNA in their plasma. Six of 21 patients (29%) with low probability scans for pulmonary embolism also had DNA in their plasma. None of the eight patients with normal scans and only one of 13 patients with myocardial infarction had DNA in their plasma. Detection of plasma DNA by CIE is a rapid and simple method of screening for pulmonary embolism.

Energy levels and patient weight in ventricular defibrillation.

In a prospective survey employing conventional devices that stored 400 joules or less, direct-current shocks that delivered 194 +/- 11 joules (1.8 joules/kg) to the chest wall terminated 45 of 46 episodes of ventricular fibrillation in 11 of 12 patients weighing 91 to 225 kg. Patients with coronary disease defibrillated more easily than patients without coronary disease. Weight did not determine outcome. The 98% defibrillation efficiency occurred at only half the energy predicted for 50% efficiency from retrospective data. Human defibrillation not only occurred at one third the untested level recommended by proponents of high-energy defibrillation, but also at one fourth the energy, defibrillating 69% of comparably heavy animals. Thus, the costly defibrillators delivering 400 to 800 joules now sold by 11 of 14 American manufacturers are superfluous, untested, potentially lethal devices with which to attempt ventricular defibrillation.

Determinants of ventricular defibrillation in adults.

Conventional defibrillators which stored no more than 400 J and used damped sine wave pulses defibrillated 240 of 253 (95%) episodes of ventricular fibrillation (VF) in 94 prospectively assessed resuscitations in 88 adults. Shocks of 80--240 J (under 3 J/kg) delivered to the chest wall defibrillated more often than higher energy levels. Defibrillation rate did not correlate with weight. Defibrillation was determined by the diagnosis and setting in which VF occurred. Patients with acute myocardial infarction (AMI) and primary VF or with coronary disease and no AMI defibrillated more easily than patients with AMI and secondary VF or with no coronary disease. VF in a terminal patient (agonal VF) defibrillated less often than VF in other clinical situations. Age, weight, delivered energy, duration of pulse wave, and duration of VF had little, if any, influence on rate of defibrillation. These data fail to support the use of more expensive, high-output defibrillators sold by 11 or 14 American manufactures.

A prospective study of plasma DNA in the diagnosis of pulmonary embolism.

To assess the usefulness of plasma deoxyribonucleic acid (DNA) detection in the diagnosis of pulmonary embolism (PE), we prospectively studied the frequency and duration of the occurrence of free plasma DNA in 23 patients with PE and in 49 patients with pneumonia, myocardial infarction, thrombophlebitis, or normal lung scans. Plasma DNA was detected in 19 of the 23 patients (83 per cent) with PE and in none of the 49 patients with other diagnoses. Eighteen of the 19 PE patients with free DNA had persistence of DNA on all subsequent sampling for up to 5 days. In this series, plasma DNA had a sensitivity of 83 per cent in the diagnosis of PE and was extremely specific for PE. Thus, detection of free plasma DNA may be useful as a rapid, noninvasive test to aid in the diagnois of PE.

Prophylaxis of infective endocarditis: a reevaluation.

Established practice dictates that physicians and dentists give antimicrobial agents at the time of procedures associated with bacteremia in an effort to prevent IE in persons with underlying cardiovascular diseases. Although prospective controlled study has not been established efficacy, very few cases of IE have been reported in patients at risk who have been treated with regimens recommended by the American Heart Association. Furthermore, studies in rabbits in recent years have shown that IE can be prevented by antimicrobials. The results in rabbits have raised some theoretical questions regarding efficacy of currently recommended regimens for man and have led some investigators to propose revisions of the American Heart Association recommendations. We feel that direct translation of results from experimental IE in rabbits into recommendations for prophylaxis of IE in man is subject to question. It is unlikely that a prospective study comparing placebo with antimicrobials will be undertaken, but it is possible and reasonable to undertake studies to document the occurrence of IE in patients at risk who are given established antibiotic regimens. With such data, modifications of established regimens could be proposed and tested. Regimens that are found to be totally effective in a large number of patients at risk might be modified toward simpler programs--for example, modifying parenteral therapy to oral therapy or changing multiple doses of antibiotic to a single dose. If regimens fail, even once in several thousand patients at risk, the factors responsible might be determined and a clear rationale for modification achieved.