Therapeutic options for severe, refractory status asthmaticus: inhalational anaesthetic agents, extracorporeal membrane oxygenation and helium/oxygen ventilation

Despite improvements in supportive care, the mortality and morbidity of asthma remain constant. The risks and incidence of morbidity related to barotrauma remain high in patients that require mechanical ventilation. The authors present three alternative strategies including the inhalation of anaesthetic agents, helium/oxygen ventilation, and extracorporeal membrane oxygenation which may be beneficial when 'conventional therapies' fail in the intubated patient with status asthmaticus.     

Modified Magnet Test for a Reversed Automatic Implantable Cardioverter Defibrillator

We present the case of a 55-year-old man with atrial septal defect and cardiomyopathy who underwent implantation of an automatic cardioverter defibrillator (AICD) for ventricular tachycardia resulting in collapse. This case demonstrates multiple unusual complications related to AICD, including rotation of the pulse generator unit about its long axis requiring a "left-handed" magnet test to determine the appropriate counts.     

A COMPARATIVE STUDY OF FOUR METHODS FOR ANALYSING REPEATED MEASURES DATA

This paper compares four alternative statistical methods for the analysis of repeated measures data. The data set involves fatty acid composition of red blood cell membrane examined after acute MI and is characterized by a moderate sample size, unbalanced repeated measures and high within-individual correlations. Two methods are based on individual curve fitting and two on the random effects model. Results yielded by the four methods differed. The advantages and disadvantages of the methods are discussed. Assumptions required for the valid application of these methods are tested.     

Self-mutilation in female remanded prisoners II: A cluster analytic approach towards identification of a behavioural syndrome

Cluster analysis of phenomenological variables and the associated symptom profile of self-mutilation in 74 female prisoners identified a subgroup with a disorder of mood who injured themselves as a symptom-relieving mechanism and received a diagnosis of borderline personality disorder (BPD). Marked differences were found between the women in this cluster in the form of their behaviour and on a range of different variables compared with a second, more heterogeneous, cluster who had injured themselves as a reaction to life-events, psychotic illness, or in a suicide attempt. The relevance of a symptom-relieving mechanism to research into self-mutilation and BPD is discussed. It is proposed that future research should concentrate on the ‘affective instability’ component of BPD and the affective symptoms reported by subjects with this diagnosis prior to impulsive behaviours such as self-mutilation.     

The in vitro erosive potential of a range of baby drinks

Objective.  The aim of this study was to assess the erosive potential of a range of commercially available baby drinks in the laboratory.
Methods.  The erosive potential of each product was assessed by measuring its initial pH, neutralizable acidity, and ability to erode primary and permanent enamel. These parameters were compared to those of an orange juice positive control.
Results.  The initial pH of the baby drinks ranged from 3.5 to 4.0 with their neutralizable acidity ranging from 5.76 to 16.02 mL of 0.1  m NaOH. The amount of primary enamel removed following 1-h immersion in the drinks ranged from 3.77 to 8.10 microns, while the amount of permanent enamel removed ranged from 1.09 to 4.86 microns. In comparison, the orange juice control (Tropicana smooth) had an initial pH of 3.86, a neutralizable acidity of 37.0 mL of 0.1  m NaOH, and removed 6.39 microns of primary enamel and 5.32 microns of permanent enamel.
Conclusion.  All the baby drinks tested were found to be erosive; some of the products were as erosive as orange juice.     

Case Studies with the Experts: Management Decisions in Atrial Fibrillation

Atrial fibrillation (AF) is the most common outpatient arrhythmia. The recent ACC/AHA/ESC guidelines outline a variety of approaches to the management of AF, but their implementation into clinical practice requires multi-faceted patient evaluations and assessments for optimizing patient care. Using a case-based approach, issues such as rate versus rhythm control, anticoagulation, cardioversion, pharmacological and catheter ablation for maintenance of sinus rhythm, and the pathophysiology of AF are discussed. These data were originally presented at a satellite symposium titled Case Studies with the Experts: Management Decisions in AF , held on May 10, 2007, during the annual Heart Rhythm Society meeting.     

Variability in Implantable Cardioverter Defibrillator Pulse Generator Longevity Between Manufacturers

ELLINOR, P.T., et al .: Variability in Implantable Cardioverter Defibrillator Pulse Generator Longevity Between Manufacturers. ICDs are used frequently to treat malignant ventricular arrhythmias. Despite the expanding role of these devices, little is known about the manufacturer variability in the performance of ICD generators. The purpose of this study is to explore the indications for ICD pulse generator replacement and to examine performance differences between the three major manufacturers of ICDs in the United States. The authors performed a retrospective review of ICD pulse generators that were implanted and replaced at Massachusetts General Hospital between February 1998 and March 2002. During the study period, 50 (7%) of the 707 devices in the study cohort were replaced. The most common indication for pulse generator replacement was related to battery performance followed by device recall, upgrade to a dual chamber device, and pulse generator malfunction. After exclusion of the recalled devices, a significantly higher number of pulse generators manufactured by St. Jude Medical (14/229) required replacement for battery depletion or prolonged charge times during the study period compared with devices from Guidant (2/220) or Medtronic (0/273),  P = 0.003  and  P < 0.0001  , respectively. This difference was attributable to reduced longevity in the Angstrom series of defibrillators. (PACE 2003; 26[Pt. I]:71–75)     

Transvenous Single Lead Atrial Defibrillation: Efficacy and Risk of Ventricular Fibrillation in an Ischemic Canine Model

Transvenous atrial defibrillation with multiple atrial lead systems has been shown to be effective in models without the potential for ventricular arrhythmias. The specific aim of this study was to evaluate the efficacy and safety of transvenous single lead atrial defibrillation in a canine model of ischemia cardiomyopathy. Ten dogs had ischemia cardiomyopathy induced by repeated intracoronary micmsphere injections. The mean LV ejection fraction decreased from 71%± 9% to 38%± 14% (P = 0.003). Spontaneous atrial fibrillation (AF) developed in four dogs, and in six AF was induced electrically. Atrial defibrillation thresholds (ADFTs) were determined with synchronous low energy shocks using a transvenous tripolar lead with two defibrillation coils (right ventricle, superior vena cava) and an integrated sensing lead (RV coil vs electrode tip). The ADFTs derived by logistic regression were compared at 50% and 90% probability of success (ED₅₀, ED₉₀): ED₅₀ was 2.4 ±1.7 J and 2.9 ±2.1 J, respectively, for 5- and 10-ms monophasic shocks, and 1.8 ± 0.9 J and 2.1 ± 1.3 J, respectively, for 5- and 10-ms biphasic shocks. Immediately after 3 of 2,179 (0.1%) synchronized shocks, ventricular fibrillation (VF) developed. VF was induced in 3 of 1,062 (0.3%) shocks with integrated sensing (RV coil vs electrode tip) compared to 0 of 1,117 shocks when a separate bipolar RV sensing electrode was used for synchronization. In our canine model of ischemic cardiomyopathy, low energy atrial defibrillation via a transvenous single lead system was highly effective. However, there was a small but definite risk of VF induction, which seemed to be greater when an integrated as opposed to a true bipolar RV sensing was used.     

Inhibition of Bradycardia Pacing Caused by Far-Field Atrial Sensing in a Third-Generation Cardioverter Defibrillator with an Automatic Gain Feature

The diagnostic accuracy of implantable Cardioverter defibrillators may be improved by automatically adjusting gain algorithms, which in general reduce the likelihood of oversensing while maintaining the ability to detect the low amplitude signals associated with ventricular fibrillation. We present a patient with a third-generation device who developed prolonged ventricular asystole arising as a complication of the automatic gain feature. During asystole the device automatically increased sensitivity in order to prevent undersensing of ventricular fibrillation, which in this case resulted in far-field sensing of atrial activity and inhibition of ventricular pacing.