Undersensing of VF in a Patient With Optimal R Wave Sensing During Sinus Rhythm

We describe a case of potentially fatal undersensing of VF by a third generation ICD with predetermined automatic gain control. In this patient, ventricular sensing was optimal, as R wave amplitudes during sinus rhythm were at least 16 mV. Cyclical, high amplitude signals during VF elevated the sensing floor to such an extent that complete undersensing of subsequent lower amplitude local electrograms occurred. This led to bradypacing and complete ICD therapy failure. Therefore, high R wave amplitudes during sinus rhythm do not warrant flawless sensing during VF. (PACE 2004; 27[Pt. I] 833–834)     

THE [LACTATE]/[PYRUVATE] RATIO AND ALCOHOL METABOLISM: EXPERIMENTS WITH NALOXONE IN FASTING NORMAL MALE VOLUNTEERS

Naloxone administration to fasting normal male volunteers reversesthe acute ethanol-induced increase in the blood [lactate]/[pyruvate]ratio, but fails to lower blood-ethanol concentration. The resultsare discussed in relation to factors affecting ethanol eliminationand the mechanism of antagonism of acute alcohol intoxicationby naloxone.     

The Nominal Group Technique: A Research Tool for General Practice?

Qualitative methods are increasingly recognized as valuable,yet practitioners face difficult decisions in their choice ofmethod and the process of analysis. The nominal group techniquecombines quantitative and qualitative data collection in a groupsetting, and avoids problems of group dynamics associated withother group methods such as brainstorming, Delphi and focusgroups. Idea generation and problem solving are combined ina structured group process, which encourages and enhances theparticipation of group members. The stages involved in conductinga nominal group are described, and practical problems of itsuse in a health care setting are discussed with reference toa study of the priorities of care of diabetic patients, carersand health professionals. Some potential applications of thetechnique in audit and exploratory research are also outlined.     

Social Media and Internet‐Based Data in Global Systems for Public Health Surveillance: A Systematic Review

Context: The exchange of health information on the Internet has been heralded as an opportunity to improve public health surveillance. In a field that has traditionally relied on an established system of mandatory and voluntary reporting of known infectious diseases by doctors and laboratories to governmental agencies, innovations in social media and so-called user-generated information could lead to faster recognition of cases of infectious disease. More direct access to such data could enable surveillance epidemiologists to detect potential public health threats such as rare, new diseases or early-level warnings for epidemics. But how useful are data from social media and the Internet, and what is the potential to enhance surveillance? The challenges of using these emerging surveillance systems for infectious disease epidemiology, including the specific resources needed, technical requirements, and acceptability to public health practitioners and policymakers, have wide-reaching implications for public health surveillance in the 21st century.Methods: This article divides public health surveillance into indicator-based surveillance and event-based surveillance and provides an overview of each. We did an exhaustive review of published articles indexed in the databases PubMed, Scopus, and Scirus between 1990 and 2011 covering contemporary event-based systems for infectious disease surveillance.Findings: Our literature review uncovered no event-based surveillance systems currently used in national surveillance programs. While much has been done to develop event-based surveillance, the existing systems have limitations. Accordingly, there is a need for further development of automated technologies that monitor health-related information on the Internet, especially to handle large amounts of data and to prevent information overload. The dissemination to health authorities of new information about health events is not always efficient and could be improved. No comprehensive evaluations show whether event-based surveillance systems have been integrated into actual epidemiological work during real-time health events.Conclusions: The acceptability of data from the Internet and social media as a regular part of public health surveillance programs varies and is related to a circular challenge: the willingness to integrate is rooted in a lack of effectiveness studies, yet such effectiveness can be proved only through a structured evaluation of integrated systems. Issues related to changing technical and social paradigms in both individual perceptions of and interactions with personal health data, as well as social media and other data from the Internet, must be further addressed before such information can be integrated into official surveillance systems.     

Prevalence of markers for hepatitis B virus and HIV-1 among drug injectors in London: injecting careers, positivity and risk behaviour

Concerns about the risks of HIV infection among drug injectors have eclipsed concerns about the prevalence and transmission of hepatitis, and in particular hepatitis B virus infection. Findings are reported from surveys undertaken with two separate community-recruited samples of drug injectors in London collected in 1992 (n = 505) and in 1993 (n = 507). Anonymized confirmed testing of saliva snows 51.5% of drug injectors in 1992 and 47.9% in 1993 to be antibody positive to the core antigen of hepatitis B virus (anti-HBc). Approximately half of the drug injectors confirmed as anti-HBc positive were unaware that they had been infected with hepatitis, Anti-HIV-1 prevalence was considerably lower at 7.0% in 1992 and 6.9% in 1993. Multivariate analyses showed anti-HBc positivity to be most likely among older injectors with longer injecting careers who had a history of having shared used needles and syringes. HIV-1 positivity was also associated with a history of having shared injecting equipment as well as with recent sharing (i.e. in the last 6 months). Unlike anti-HBc positivity, there were no associations between HIV-1 positivity and age or length of injecting career. Younger injectors with shorter injecting careers were more likely to report recent sharing of used injecting equipment than older injectors with longer injecting careers. We note the potential for continued transmission of HBV and HIV-1, particularly among younger injectors. We recommend an integrated strategy to maximize the health of drug injectors, of which HIV and HBV prevention is a part. There is a need to widen the availability of HBV vaccinations for HBV negative drug injectors and their sexual partners and for clear guidelines to drug injectors about the relative efficacy of bleach to disinfect injecting equipment of HBV and HIV.     

Supraventricular Electrical Interaction in Conjoined Twins with Common Coronary Sinus

Conjoined twins with echocardiographic evidence of continuity of the coronary sinuses had identical heart rates on ECG. Both had broad, polyphasic QRS complexes, and various imaging modalities were unable to determine whether there was ventricular myocardial continuity. Administration of adenosine demonstrated that the broad polyphasic complexes were a "fusion" of the twins' individual QRS complexes, which could be clearly distinguished after administration of the drug. Ventricular pacing resulted in dissociation of the individual QRS complexes, thus demonstrating an absence of ventricular myocardial continuity. This was confirmed when the twins were successfully separated at the age of 10 months.     

Non–response bias in alcohol and drug population surveys

Introduction and Aims. This proposed study was to assess non‐response bias in the 2004 Canadian Addictions Survey (CAS). Design and Methods. Two approaches were used to assess non‐response bias in the CAS which had a response rate of only 47%. First, the CAS sample characteristics were compared with the 2002 Canadian Community Health Survey (CCHS, response rate 77%) and the 2001 Canada Census data. Second, characteristics of early and late respondents were compared. Results. People with lowest income and less than high‐school education and those who never married were under‐represented in the CAS compared with the Census, but similar to the CCHS. Substance use was more prevalent in the CAS than the CCHS sample, but most of the CAS and CCHS estimates did not exceed±3% points. Late respondents were also significantly more likely to be male, young adult, highly educated, used, have high income, live in different provinces and report substance use. Multivariate logistic regression found significant non‐response bias for lifetime, past 12 months, chronic risky, acute risky and heavy monthly alcohol use, lifetime and past year cannabis use, lifetime hallucinogen use, any illicit drug uses of lifetime and past year. Adjustment for non‐response bias substantially increased prevalence estimates. For example, the estimates for lifetime and past 12 month illicit drug use increased by 5.22% and 10.34%. Discussion and Conclusions. It is concluded that non‐response bias is a significant problem in substance use surveys with low response rates but that some adjustments can be made to compensate.[Zhao J, Stockwell T, Macdonald S. Non‐response bias in alcohol and drug population surveys. Drug Alcohol Rev 2009]