A DYNAMO application of microcomputer-based simulation in health sciences teaching.

This paper presents a concrete application of microcomputer-based simulation in health sciences education. It shows a pharmacological system dynamics model representing graphics and numerical behaviour and relations between variables, which in addition allows interaction with students for experimentation. The work also illustrates a strategy for introducing this kind of model in the classroom, as well as the suitability of their implementation, in educational environments, using professional tools such as DYNAMO and DYNEX. Subsequent evaluation of the results and comments given by the students revealed more positive attitudes towards the discipline.

[Age as a prognostic factor in intensive care]. / La edad como factor pronóstico en cuidados intensivos.

In order to define the prognostic impact of the age of critical patients as well as its association with the initial severity of illness (SAPS index) and therapeutic effort (TISS index), we studied 1.102 patients older than 14 years admitted consecutively to 3 general intensive care units. The oldest patients (more than 65 years) showed a higher mean SAPS (11.00 versus 8.58, p less than 0.0001) and mortality (odds ratio = 1.99, p less than 0.0001) than the younger ones. The association between age and mortality showed a "dose-response" pattern, even after controlling for the effect of initial severity (p less than 0.0001). The effect of age was stronger in the groups of patients with low SAPS (odds ratio = 2.94, p = 0.0007) or admitted for acute myocardial infarction (odds ratio = 3.28, p less than 0.0001). The oldest group showed a lower TISS/SAPS ratio and a shorter stay in the intensive care unit than younger patients, suggesting a low relative therapeutic effort in the latter. The differential therapeutic effort did not explain, however, the mortality excess in the oldest group, because the gradient of mortality increased after adjusting for TISS/SAPS ratio (adjusted odds ratio = 2.42, p less than 0.0001).

[Autonomic cardiovascular dysfunction in multiple sclerosis not caused solely by brain stem lesions]. / Disfunción autonómica cardiovascular en la esclerosis múltiple no provocada únicamente por lesiones troncoencefálicas.

INTRODUCTION: Multiple sclerosis (MS) can cause alterations in autonomic cardiovascular functioning. Some authors attribute these anomalies detected in MS patients to brain stem lesions, due to the fact that important autonomic nuclei are located in this region of the brain. Other studies, however, have been unable to prove such a relation. AIMS. The purpose of this study was to analyse whether these alterations had an exclusive relation with the brain stem lesions that usually appear in the course of this disease. PATIENTS AND METHODS: We compared the spectral analysis of the heart rate variability (SAHRV) in the frequency domain between a group of 34 patients with MS and another group of 14 patients with isolated brain stem lesions (IBSL) of a non inflammatory origin, which were measured using a 24 hour Holter recording. RESULTS: Heart rate, very low rates, low rates and the low rate/high rate quotient are significantly higher in the MS group than in the IBSL group, even when the former present brain stem lesions. Results in the high rate component, however, depend on the presence of brain stem lesions in the MS group. CONCLUSION: These findings suggest that autonomic cardiovascular dysfunction in MS is only related with brain stem lesions, although we obtained results that confirm the importance of this area in cardiovascular innervation.

Heart rate variability in multiple sclerosis during a stable phase.

OBJECTIVES: Multiple sclerosis (MS) frequently causes disturbances of autonomic functions. Cardiovascular dysautonomia has been studied by classic autonomic tests and, recently, by heart rate variability analysis in some isolated periods. Multiple authors recommended performing heart rate variability analysis with a 24 h ECG recording to increase its sensitivity. MATERIAL AND METHODS: We analyzed the heart rate variability in time and frequency domains in 34 MS patients and 24 age and sex-matched healthy control subjects, in order to evaluate the effects of MS on sympathetic and parasympathetic cardiovascular regulatory functions measured from 24-h electrocardiogram. RESULTS: Low frequency power (0.01) and low frequency/high frequency power (0.01) were significantly higher in multiple sclerosis patients independently, all together or in subgroups. Very low frequency (0.01) and high frequency (0.001) power were higher in less affected multiple sclerosis patients. Variability in time domain (0.05) were lower in most affected multiple sclerosis patients. CONCLUSIONS: These results suggest that multiple sclerosis causes cardiovascular autonomic dysregulation manifesting as impaired heart rate variability. This illness seems to cause an increase in sympathetic cardiovascular tone; the parasympathetic tone is most variable and depends on clinical and paraclinical findings, but the illness progression seems to provoke a decrease in it.

[Utilization of a hospital emergency service. Influence of the need to transfer to another location and previous medical attention]. / Utilización de un servicio de urgencias hospitalario. Influencia del traslado de localidad y de la asistencia médica previa.

171 cases consecutively seen in a hospital emergency service were prospectively evaluated. Several data were recorded to assess the type of care given and the need for attention in an institution with the technical resources of a hospital. These data were evaluated considering whether the user had moved from another town to receive attention and whether he had been referred by a physician or not. There were definite differences in the behavior of the user from the town where the hospital is located and the remaining users. These differences were not attributable to a different performance or evaluation from the primary care services of the several towns involved. It was concluded that, at the present time, the use of the emergency service of our hospital is significantly influenced by the decision of the user to consult the service. Factors other than the severity of the disease influence this decision.

Brainstem lesions decrease heart rate variability.

OBJECTIVE: Brainstem is an essential region in the regulation of the autonomic cardiovascular functions. Some authors have reported that medulla oblongata is very important in this regulation, but probably is not the unique because the sympathetic cardiovascular centers are spread in the brainstem. Since some years ago, we are able to measure heart rate variability which is a useful tool for assessing quantitatively both sympathetic and parasympathetic autonomic effects on the heart. The objective is to evaluate the effects of isolated brainstem lesion (IBL) on sympathetic and parasympathetic cardiovascular regulatory functions. PATIENTS AND METHODS: We analyzed the heart rate variability in time and frequency domains in 14 IBL patients and 25 age and sex matched healthy control subjects, measured from 24-h electrocardiogram. RESULTS: Low frequency power (0.001) and low frequency/high frequency power (0.05) were significantly higher in control subjects independently, all together or in subgroups (medulla oblongata affected or not). High frequency power (0.05) were higher too in control subjects. Variability in time domain (0.001 and 0.01) was lower when the medulla oblongata was affected. CONCLUSIONS: These results confirm that brainstem lesions cause cardiovascular autonomic dysregulation overall when the medulla oblongata is affected. The importance of this region in parasympathetic and sympathetic cardiovascular functions is showed. However, pontine and mesencephalic lesions seem to provoke a decrease only in sympathetic regulation.