A. Larry Wright

Prehospital cardiac arrest: The impact of witnessed collapse and bystander CPR in a metropolitan EMS system with short response times

Objective: Numerous studies have shown initiation of bystander CPR to significantly improve survival from prehospital cardiac arrest. However, in emergency medical services (EMS) systems with very short response times, bystander CPR has not been shown to impact outcome. The purpose of this study was to determine the effect of bystander CPR on survival from out-of-hospital cardiac arrest in such a system. Design: Prehospital, hospital, and death certificate data from a medium-sized metropolitan area were retrospectively analyzed for adult, nontraumatic cardiac arrest during a 16-month period. Results: A total of 298 patients met study criteria. One hundred ninety-five arrests (65.4%) were witnessed, and 103 (34.6%) were unwitnessed. Twenty-five witnessed victims (12.8%) were discharged alive, whereas no unwitnessed victims survived ( P P P P Conclusion: Our data revealed improved survival rates when bystander CPR was initiated on victims of witnessed cardiac arrest in an EMS system with short response times.

Two strong limit theorems for processes with independent increments

Two related almost sure limit theorems are obtained in connection with a stochastic process {[xi](t), -[infinity] 0 for almost all sample functions of the process. The second result deals with a wide-sense stationary process whose random spectral distributions is [xi]. It addresses the question: Under what conditions does converge as T --> [infinity] for all [tau] for almost all sample functions?

Hepatitis B and vaccination in emergency physicians

The seroprevalence of hepatitis B virus (HBV) markers in emergency physicians has been shown to be approximately 13%, roughly three times the prevalence in the general population. Frequent contact with blood and body secretions of potentially infectious patients undoubtedly is a major factor in the increased seroprevalence and risk of hepatitis B. The potential sequelae of HBV infection include chronic active hepatitis, cirrhosis, primary hepatocellular carcinoma, and development of the chronic carrier state, any of which may have a devastating impact on the personal health and professional career of the emergency physician. A vaccine against hepatitis B has been available since 1982 and has been found to be effective in approximately 90% of vaccinees. The vaccine is generally well tolerated; the most common side effects are reactions at the injection site, although systemic side effects may occur. The risk of serious illness due to the vaccine is very low. Using a risk/benefit analysis to assess the risks of hepatitis B and the risks and benefits of HBV vaccination, it is clear that HBV vaccination should be accepted by the emergency physician to minimize the risk of contracting hepatitis B.

On the inconsistency of Bayesian non-parametric estimators in competing risks/multiple decrement models☆

Abstract In the competing risks/multiple decrement model, the joint distribution is often not identifiable given only the observed time of failure and the cause of failure. The traditional approach is consequently to assume a parametric model. In this paper we shall not do this, but rather assume a Bayesian stance, take a Dirichlet process as a prior distribution, and then calculate the posterior distribution given the data. In this paper we show that in dimensions ⩾ 2, the posterior mean yields an inconsistent estimator of the joint probability law, contrary to the common assumption that the prior law ‘washes out’ with large samples. For single decrement mortality tables however, the non-parametric Bayesian method allows a flexible method for adjusting a standard mortality table to reflect mortality experience, or covariate information.

Some methods for simulating random fields

Several methods exist for simulating random fields. This paper reviews some of the methods used to simulate stationary random fields in Rn, n ≥ 1. A recent study comparing the traditional turning bands method to a method called the random impact method is given. The results of this study indicate that the random impact model is comparable to the turning bands method in terms of execution time, and in terms of reproducibility of the covariance functions.