NASPE POLICY STATEMENT The NASPE* BPEG** Defibrillator Code

BERNSTEIN, A.D., et al .: The NASPE/BPEG Defibrillator Code. A new generic code, patterned after and compatible with the NASPE/BPEG Generic Pacemaker Code (NBG Code) was adopted by the NASPE Board of Trustees on January 23, 1993. It was developed by the NASPE Mode Code Committee, including members of the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG). It is abbreviated as the NBD (for NASPE/BPEG Defibrillator) Code. It is intended for describing the capabilities and operation of implanted cardioverter defibrillators (ICDs) in conversation, record keeping, and device labeling, and incorporates four positions designating: (1) shock location; (2) antitachycardia pacing location; (3) means of tachycardia detection; and (4) antibradycardia pacing location. An additional Short Form, intended only for use in conversation, was defined as a concise means of distinguishing devices capable of shock alone, shock plus antibradycardia pacing, and shock plus antitachycardia and antibradycardia pacing. (PACE, Vol. 16, September 1993)     

Effect of intravenous magnesium sulphate on airway calibre and airway reactivity to histamine in asthmatic subjects

In a randomized, double-blind, placebo controlled cross-over study we have investigated the effect of intravenous magnesium on airway calibre and airway reactivity to histamine in 20 subjects with mild to moderate asthma. After baseline measurements of forced expiratory volume in one second (FEV₁), subjects received 100 ml normal saline with or without 2 g of magnesium sulphate by infusion over 20 min. Measurements of FEV₁ were repeated at 5 min intervals throughout the infusion, and the provocative dose of histamine required to drop the FEV₁ by 20% from baseline ( PD ₂₀FEV₁) was determined at 20 min. The area under the curve (AUC) in litre minutes for change from baseline in FEV₁ between 0 and 20 min was significantly higher on the magnesium study day (mean difference in AUC (95% CI) 1.71 (0.02-3.4), P = 0.049). The increase in FEV₁ from baseline with magnesium relative to saline was maximal at 20 min (mean difference (95% CI) 0.13 (0.02-0.23) 1, P = 0.01). Log P D ₂₀FEV₁ to histamine was not significantly different after magnesium and saline (mean difference in log P D ₂₀FEV₁ (95% CI) 0.04 (-0.19 to 0.27), P = 0.7). We conclude that intravenous magnesium is a weak bronchodilator but does not alter airway reactivity at this dose in stable asthmatic subjects.     

Corrosion of Pacemaker Electrodes

As improvements in pacemaker components and design increase pacemaker life, problems with other components may emerge such as corrosion of the electrodes. Explanted electrodes were examined under a scanning electron microscope and the degree of corrosion was graded and correlated with the reasons for expiantation, the status of the explanted pacemaker, and the duration of the implant. Fifty-six explanted electrodes were removed for loss of capture or sensing, pacemaker extrusion, broken wires, or after death. A numerical grading system was used to qualitate the degree of corrosion. The pacemaker itself was retrieved in 50 cases, permitting evaluation of the entire pacing system. The dc component of the pacemaker output was measured. Without She aid of magnification most electrodes appeared shiny and smooth. With one exception all corrosion was microscopic. Significant corrosion was seen on all pacemaker electrodes that had been connected to pacemakers with dc offset currents greater than 5 microamperes. All except the "youngest" explanted electrode showed some degree of corrosion. The data suggest that corrosion was directly related to the duration of implantation. With the possible exception of one case, no consistent adverse clinical effects were observed, even when electrodes were heavily corroded. Whether or not corrosion eventually will progress to the point that clinical problems become manifest cannot be predicted at this time.     

Synergism between halothane and labetalol

A patient in chronic renal failure, who was receiving large doses of the combined alpha- and beta-blocking agent, labetalol, was selected for renal transplantation. A low concentration of halothane was used for induction and maintenance of anaesthesia, but severe myocardial depression occurred which proved unresponsive to atropine or isoprenaline, although it responded to a dopamine infusion. Synergism has already been reported between labetalol and high concentrations of halothane, but this case suggests that, in patients with previous myocardial damage, much lower concentrations of this inhalational agent may prove fatal.     

The validity and reliability of a new examination of the clinical competence of medical students

In a previous study we described a problem-based criterion-referenced test of the clinical competence of medical students which was felt to offer advantages over the traditional final-year examination. This paper reports the validity and reliability studies on which it is possible to judge the value of this new test when compared to the traditional approach.
The results demonstrate a high level of content validity and provide evidence of the construct validity of the test. Efforts to obtain measures of concurrent and predictive validity were thwarted by a failure to attain reliable assessments of ward performance from resident and consultant staff. Satisfactory levels of internal consistency were established for the whole test. Marker reliability was satisfactory in all sections of the test except for those requiring examiners to rate practical clinical skills. This was so despite the use of simulated patients, behavioural check-lists and rater training. Possible solutions to this problem are discussed.
It is concluded that this new approach overcomes many of the measurement problems inherent in the traditional final examination. It has been shown to be feasible to construct and administer in the medical school setting without the need for the allocation of additional resources.     

Dendritic Cell Numbers in the Blood of HIV-1 Infected Patients Before and After Changes in Antiretroviral Therapy

Antigen presenting dendritic cells (DCs) can serve as sites for HIV replication and as vehicles for transmission of the virus to T cells. It is known that the numbers of DCs in blood is reduced during HIV-1 infection. Here we monitored the two major subsets of blood DCs in 12 individuals undergoing a change, primarily initiation, of highly active antiretroviral therapy. The numbers of plasmacytoid DCs were reliably higher on therapy, although in the 1–3 month interval we followed, these numbers did not return to those seen in HIV uninfected controls. An increase in plasmacytoid DCs was accompanied by an increase in IFN- production in response to a standard challenge in culture with UV-inactivated herpes simplex virus. The levels of myeloid DCs also demonstrated an increase while on HAART, and these numbers become comparable to the HIV uninfected controls. The numbers of plasmacytoid and myeloid DCs varied inversely with the levels of plasma HIV viremia. These longitudinal studies extend prior work showing that virus infection with HIV leads to a decrease in the number of dendritic cells in blood, and that this can be reversed at least in part by therapy.     

Transplantation of Autologous Keratinocyte Suspension in Fibrin Matrix to Chronic Venous Leg Ulcers: Improved Long-Term Healing after Removal of the Fibrin Carrier

BACKGROUND The transplantation of keratinocytes suspended in fibrin carrier represents a candidate regimen for chronic ulcer treatment in an outpatient setting. We evaluated the integration and survival of autologous individualized keratinocytes applied within fibrin matrix onto chronic venous leg ulcers in vivo. Parallel in vitro culture was used to validate keratinocyte survival and apoptosis in fibrin compared to collagen matrix carrier.
METHODS Seven patients with chronic venous leg ulcers were transplanted with autologous keratinocytes suspended in fibrin sealant after isolation and expansion from full-skin biopsy. The fibrin carrier was removed in three patients after 7 days, whereas four patients served as control with fibrin remaining. In parallel in vitro cultures, primary keratinocyte movement in fibrin as well as viability in three-dimensional (3D) fibrin versus collagen lattices was examined.
RESULTS Complete ulcer healing was observed in four of seven ulcers after a mean duration of 14.5 weeks. If the fibrin layer was removed, complete wound healing occurred in three of three patients, compared to one of four in the control group. In vitro, keratinocytes formed a monolayer underneath but remained isolated and nonmobile within the fibrin matrix, suggesting reepithelialization along the lower fibrin interphase. Keratinocyte culture in 3D fibrin at clinically used concentration (90 mg/mL) caused high levels of apoptosis, similar to 3D collagen, which was prevented by diluting fibrin concentration to 3 mg/mL.
CONCLUSIONS Transplantation of autologous keratinocytes suspended in fibrin is efficient in the treatment of chronic venous leg ulcers. Due to an antimigratory and survival-compromising effect, the presently used fibrin carrier should be removed after a few days of transplantation.