Deja vu: nosocomial hepatitis B virus transmission and fingerstick monitoring.

PURPOSE: Three patients with acute hepatitis B virus infection were identified who had been hospitalized on the same medical ward during a 19-day period several months earlier. An investigation was undertaken to determine if nosocomial transmission had occurred. SUBJECTS AND METHODS: A cohort study of patients admitted to the medical ward during the 19-day period in 1995 was conducted. In addition, we reviewed medical charts and laboratory records of all patients with acute hepatitis B virus infection who had been admitted to the hospital from 1992 through October 1996 to identify other cases with possible nosocomial acquisition. RESULTS: The 3 patients who had developed acute hepatitis B infection 2 to 5 months after hospitalization on the same medical ward had diabetes mellitus but no identified risk factors for hepatitis B infection. A source patient with diabetes mellitus and hepatitis B "e" antigenemia also was present on the same medical ward at the same time; all 4 patients were infected with the same viral subtype (adw2). Diabetes mellitus and fingerstick monitoring were associated with illness (P <0.001). Through the review of medical charts and laboratory records, 11 additional cases of suspected nosocomial acquisition via fingersticks were identified in 1996, including two clusters involving an unusual subtype of hepatitis B virus (adw4). The fingerstick device employed had a reusable base onto which disposable lancet caps were inserted. There was ample opportunity for cross-contamination among patients because deficiencies in infection control practices, particularly failure to change gloves between patients, were reported by nurses and patients with diabetes mellitus. CONCLUSION: Transmission during fingerstick procedures was the most likely cause of these cases of nosocomial hepatitis B infection. Contamination probably occurred when healthcare workers failed to change gloves between patients undergoing fingerstick monitoring, although other means of contamination cannot be ruled out.

Dynamic properties of cardiovascular systems.

A recently derived mathematical model of an isolated heart is extended here to a closed-loop cardiovascular system. Taking the end-diastolic volume as state variable, the authors show that the closed-loop cardiovascular system can be described by a one-dimensional nonlinear discrete dynamical system that depends on parameters describing the systolic and diastolic properties of the heart, heart rate, total peripheral resistance, and arterial capacitance. Studies of this model show that the system possesses a rich spectrum of dynamical behavior, from stable points through stable cycles to a "chaotic" behavior. It is shown that such an analysis of dynamic behavior yields those domains in the parameter space that correspond to a normal and abnormal beating heart, when the heart ejects time-invariant and time-variant (periodic or aperiodic) stable stroke volumes, respectively. Determination of such domains may lead to better understanding of the specific pathologic mechanism involved in the evolution of an abnormal beating heart.

Periodicities of cardiac mechanics.

Using a finite-difference equation to model cardiac mechanics, we simulated the stable action of the left ventricle. This model describes the left ventricular end-diastolic volume as a function of the previous end-diastolic volume and several physiological parameters describing the mechanical properties and hemodynamic loading conditions of the heart. Our theoretical simulations demonstrated that transitions (bifurcations) can occur between different modes of dynamic organization of the isolated working heart as parameters are changed. Different regions in the parameter space are characterized by different stable limit cycle periodicities. Experimental studies carried out in an isolated working rat heart model verified the model predictions. The experimental studies showed that stable periodicities were invoked by changing the parameter values in the direction suggested by the theoretical analysis. We propose in the present work that mechanical periodicities of the heart action are an inherent part of its nonlinear nature. The model predictions and experimental results are compatible with previous experimental data but may contradict several hypotheses suggested to explain the phenomenon of cardiac periodicities.

Stability analysis of one-dimensional dynamical systems applied to an isolated beating heart.

In this paper we propose a new model of an isolated beating heart. The model is described by a one-dimensional non-linear discrete dynamical system which depends on several parameters. Applying stability analysis we investigate the dynamic properties of the non-linear system. We find those domains in the parameter space in which the equilibrium point of the system (the fixed point) and the periodic orbits are attractors and in which they are unstable. These domains correspond to a normal and abnormal beating heart, i.e. when the end diastolic volumes are stable time invariant and time variant, respectively. On transition between these domains there is a bifurcation which gives rise to a pair of attracting points of period 2. This case corresponds to the simplest type of period doubling behavior of an abnormal beating heart, called mechanical alternans. Our results provide qualitative and quantitative predictions which can be used for comprehensive experimental design.

Prolapse of gastrostomy tube resulting in entero-enteric fistula and intussusception.

A case is reported in which a surgical gastrostomy tube migrated into the duodenum and eroded through the jejunal wall into an adjacent loop of jejunum. This resulted in an entero-enteric fistula, small bowel obstruction and intussusception. Since the number of gastrostomy tubes being placed endoscopically and surgically is increasing, gastroenterologists and surgeons should be alerted to these and other potential complications.

Marked elevation of transaminases and alkaline phosphatase during asymptomatic cholangitis associated with calcific pancreatitis-induced common bile duct stricture.

Cholestasis due to chronic pancreatitis has been well documented. Previous reports describe the gamut of biochemical, radiological and clinical findings in these patients. We wish to present the unusual association of a relatively asymptomatic cholangitis due to common bile duct (CBD) stricture induced by calcific pancreatitis.