A Quantitative Measurement of Spatial Orderin Ventricular Fibrillation

Quantifying Spatial Order in Fibrillation. Introduction: The degree of organization in ventricular fibrillation (V F) is not known. As an objective measurement of spatial order, spatial correlation functions and their characteristic lengths were estimated from epicardial electrograms of pigs in VF.
Methods and Results: VF was induced by premature stimulation in five pigs, EIectroj;raniswere simultaneously recorded with a 22 × 23 array of unipolar electrodes spaced 1.12 mmapart, Data were obtained by sampling the signals at 2000 Hz for 20 minutes immediately afterthe initiation of VF. Correlations between all pairs of signals were computed at various times.Correlation lengths were estimated from the decay of average correlation as a function of electrode separation. The correlation length of the VF in pigs was found to be approximately 4 to 10 mM. varying as fihrillation progressed. The degree of correlation decreased in the first 4 seconds after fibrillation then increased over the next minute.
Conclusion: The correlation length is much smaller than the scale of the heart, suggestingthat many independent regions of activity exist on the epicardium at any one time. On theother hand, the correlation length is 4 to 10 times the interelectrode spacing, indicating thatsome coherence is present. These results imply that the heart behaves during VF as a highdimensional, but not random, system involving many spatial degrees of freedom, which mayexplain the lack of convergence of fractal dimension estimates reported in the literature.Changes in the correlation length also suggest that VF reorganizes slightly in the first minuteafter an initial breakdown in structure.     

Pharmaceutics: The Effect of Dose on the Characterization of Aerodynamic Particle-size Distributions of Beclomethasone Dipropionate Metered-dose Inhalers

The aerodynamic particle-size distribution for two doses of a Becloforte metered-dose inhaler (MDI) was measured by use of a twin-stage impinger (TSI), the new multi-stage (five-stage) liquid impinger (MSLI) and the Andersen cascade impactor (ACI) (n = 5 for each apparatus). The mean (s.d.) fine-particle doses measured by the three techniques for the Becloforte MDI were 40.3 (1.2), 45.7 (0.5) and 41.8 (0–4)% w/w, respectively; the median mass aerodynamic diameters (MMAD) measured using the MSLI and the ACI were 3.50 and 3.73 μm, respectively. The MSLI fine particle (< 6.8 μm) doses for 2, 5, 10, 20, 30 and 40 doses from Becloforte MDIs (n = 5 for each dose) were 49.7 (0.7), 52.9 (1.2), 45.3 (0.6), 45.5 (0.71), 45.9 (0.7) and 46.4 (0.7)% w/w, respectively. Values obtained using the ACI (< 5.8 μm) were 40.8 (1.0), 41.0 (0.8), 44.4 (0.5), 43.1 (0.4), 42.8 (0.5) and 40.4 (0.4)% w/w (n = 4). MMAD values measured with the MSLI were 3.39, 3.46, 3.75, 3.91, 4.15 and 4.45 μm, respectively; using the ACI they were 3.46, 3.54, 3.61, 3.66, 3.73 and 3.85 μm. The results indicate that the measured aerodynamic particle-size distributions of beclomethasone dipropionate MDIs are affected by the dose dispensed and by the apparatus used for measurement.     

Smoking habits in relapsed subjects from a smoking cessation trial after one year

Reports of smoking cessation studies often claim that many relapsed subjects reduce their smoking. We investigated the smoking habits of relapsers 1 year after quitting in a smoking cessation trial using nicotine or placebo patches. All 289 participants in that study were summoned to a 1-year follow-up visit–148 (57%) of 259 relapsers attended, as did all 30 sustained abstainers. Fewer than 1% of the subjects had quit spontaneously after the primary relapse. Daily cigarette consumption, standard nicotine yield per cigarette, saliva cotinine concentration, expired carbon monoxide level and two nicotine dependency scales were assessed at entry and at the 1-year follow-up. In five of these six smoking-related characteristics, there was a small but significant mean reduction of 7%-27%. A significant weight gain of 0.5 ± 2.9 kg (mean ± SD) was recorded in the relapsers compared with 4.8 ± 4.2 kg for abstainers (p < 0.001). It is concluded that smoking habits in relapsers are relatively unchanged, and thus the most important outcome measure in smoking cessation trials is abstinent subjects.     

Clinicians'' assessment of stress occurring with toddler''s diarrhoea

From biographical and behavioural data, four clinicians independently rated the degree of stress as either due to general environmental influences or induced by family relationships likely to act upon two groups of children--one with toddler's diarrhoea and a matched control group with other physical disorders. Each clinician rated the experimental group significantly higher on both scales of stress than the control group; inter-rater correlation was positive and significant. The results suggest that environmental stress influences are associated with the aetiology and maintenance of toddler's diarrhoea, and imply that modification of such stress is relevant to treatment of the condition.     

Bleeding peptic ulcer: An evolving role for surgical intervention

Abstract Early surgical intervention was previously advocated in patients > 60 years with bleeding peptic ulcer presenting with haemodynamic instability or ongoing transfusion requirements. It is, however, well recognized that emergency surgical intervention with its inherent risks must be reserved for highly selected patients in whom endoscopy initially fails to control exsanquinating haemorrhage or in whom life-threatening bleeding recurs. Therapeutic endoscopy for bleeding ulcer has led to a remarkable decline in rebleeding rates, the need for emergency surgery and mortality. Octogenarians are at risk, particularly when ulcer size exceeds 2 cm. Poor surgical candidates make up two-thirds of patients with major ulcer bleeding and operation is to be avoided if at all possible. Medical therapy with proton pump inhibitor and subsequent eradication of Helicobacter pylori following endoscopic treatment has been shown to be beneficial to outcomes. Should surgery be deemed necessary, it is likely that laparoscopic techniques to control bleeding, with or without the addition of an acid-reducing procedure, will find a role in haemodynamically stable patients undergoing operation on an early elective basis.