Article Types

Letters

Cardiovascular diseases Letters 6 March 2017 Free

Public access defibrillation: emerging importance of automated external defibrillators as a diagnostic clinical tool

To the Editor:The use of public access automated external defibrillators (AEDs) has rapidly increased from 2003 to 2013 — with an 11-fold growth in Victoria — and has shown improvement in survival rates for out-of-hospital cardiac arrest.1 Prompt deployment relies on lay people to recognise a cardiac arrest, operate the device and manage basic life support.2 Lay people’s use of these devices located in public locations, as opposed to specialised health care settings, is unparalleled among medical devices. However, lay people are not involved in the clinical handover of the patient with the AED and it often remains with the private owner, who may not appreciate the importance of retrieving critical AED data. Lack of handover postresuscitation of initial rhythm and AED data has been shown to underdiagnose ventricular fibrillation (VF), as well as miss other significant rhythms such as complete heart block.3,4 AEDs use arrhythmia algorithms to analyse heart rate and QRS duration from the triggered digital recording, and are designed to have a specificity of 99% and a sensitivity of > 90% for detection of VF and of > 75% for rapid ventricular tachycardia (VT), without a specific cut-off rate defined. Of four commercially available AEDs, one study indicated a large divergence in how they managed VT and supraventricular tachycardia (SVT), with some devices even delivering a shock for narrow complex SVT, therefore leading to difficulty for clinicians in interpreting the significance of an AED delivered shock.5 Specific equipment operated by trained personnel is required to download the rhythm data from the AED.2 Standardised data transmission software, either via smartphone or cellular networks, to a central server or at the hospital may fill this current critical data void. Systematic capture and documentation of the initial AED rhythm analysis may incorporate the AED as an essential diagnostic clinical tool and may reduce critical diagnostic errors and unnecessary use of implantable cardioverter defibrillators. Rhythm documentation of AED data has significant implications in determining underlying cardiac disease, dictating management and influencing preventive measures to reduce the risk of malignant arrhythmia recurrence. With the rapid expansion and increasing access of AEDs in the public domain, collaborative review of current protocols and coordination between health services, emergency management services and owners of public AEDs are required to avoid further loss of crucial data.

Andrew D Mulligan · Omar Al-Mukhtar · Michael Wong

Health services administration Letters 6 March 2017 Free

The economic benefits of eliminating Indigenous health inequality in the Northern Territory

To the Editor:Zhao and colleagues1 quantified the burden of indigenous health inequality in Australia’s Northern Territory. Any physician who has worked in the NT would agree, although the quantum calculated may shock readers. However, Zhao and colleagues appear to have left out an epidemiological principle in presenting their analysis: stratify appropriately, or risk unbeknown confounding. The authors have not taken into consideration the differences between the regions where Indigenous Australians live. The detrimental causes affecting Indigenous populations in the NT are more intense there than among Indigenous people on Australia’s eastern coast, for example, and increase as one moves away from Darwin to remote areas, across the whole spectrum of causes of inequality. Gray and colleagues,2 cited in the article, list many of the causes of Indigenous health inequality, including “lower levels of education, training and skill levels, … living in areas with fewer labour market opportunities, higher levels of … interactions with the criminal justice system, … and lower levels of job retention”. Employment, or lack of it, integrates and acts as a proxy measure of effect for many of these causes. If Zhao and colleagues had considered this variability of effect, they might have realised that the statement that “between 1994 and 2008, Indigenous employment in Australia increased by 55–70%” is misleading. If Australia is to close the gap between its Indigenous and non-Indigenous people, the government needs to recognise this spectrum of effect across the continent.

Richard X Davey

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