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ABSTRACT: In this paper, using cross sectional data from the Encuesta de Presupuestos Familiares 1990/91, we develop a model that seeks to explain the individual decisions in housing tenure choice at the Canary Islands, being considered this one under four types: homeownership in the free-market, homeownership in the subsidised housing market, rent in the free-market, and, rent in the subsidised housing market. With this aim, we first elaborate a hedonic price model that allows us to obtain an estimation of the subjective valuation carried by the people on the different housing characteristics. After that, we proceed to estimate a mixed logit model to approximate the fundamental variables that determine the housing tenure choice. The results obtained permit us to overcome the simplifying assumptions underlying the family of logit models most widely utilized nowadays in the modelization of housing tenure choice, these are the multinomial and nested logit, in particular, the independence of irrelevant alternatives and the homoscedasticity hypotheses.
Estudios de economía aplicada, ISSN 1697-5731, Vol. 21, Nº 1, 2003, pags. 173-191. 05/2013;
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ABSTRACT: En este trabajo, empleando datos de corte transversal procedentes de la Encuesta de Presupuestos Familiares 1990/91, desarrollamos un modelo que persigue explicar las decisiones que adoptan los individuos de las Islas Canarias en materia de tenencia de vivienda, considerándose esta bajo cuatro supuestos: propiedad en el mercado libre, propiedad en el mercado de protección oficial, alquiler en el mercado libre, y, alquiler en el mercado de protección oficial. Para ello se elabora en primer lugar un modelo de precios hedónicos que no permite obtener una estimación de la valoración subjetiva que realiza la población sobre las diferentes características de la vivienda. Basándonos en este, procedemos a la estimación de un modelo logit mixto que aproxima las variables fundamentales que determinan la elección del régimen de tenencia. Los resultados obtenidos permiten superar los supuestos simplificadores propios de la familia de modelos logit más ampliamente utilizados hasta el momento en la modelización de la elección de tenencia de vivienda, el logit multinomial y anidado, y que se corresponden con las hipótesis de independencia de alternativas irrelevantes y homoscedasticidad. In this paper, using cross sectional data from the Encuesta de Presupuestos Familiares 1990/91, we develop a model that seeks to explain the individual decisions in housing tenure choice at the Canary Islands, being considered this one under four types: homeownership in the free-market, homeownership in the subsidised housing market, rent in the free-market, and, rent in the subsidised housing market. With this aim, we first elaborate a hedonic price model that allows us to obtain an estimation of the subjective valuation carried by the people on the different housing characteristics. After that, we proceed to estimate a mixed logit model to approximate the fundamental variables that determine the housing tenure choice. The results obtained permit us to overcome the simplifying assumptions underlying the family of logit models most widely utilized nowadays in the modelization of housing tenure choice, these are the multinomial and nested logit, in particular, the independence of irrelevant alternatives and the homoscedasticity hypotheses.
Estudios de Economía Aplicada. 02/2003; 21(Abril):173-191.
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ABSTRACT: The median sternotomy is still the gold standard of cardiac surgery approaches. The main disadvantages of this cardiac access are osteomyelitis and mediastinitis which are infrequent but very serious; the aesthetic impact of a large and visible scar from the median lane and lastly respiratory failure consecutive to pain and sternal dehiscence. Other pathways have been developed in trying to reduce these complications and lessen the length of stay, pain and costs. From the many variants described up until now, the "J" ministernotomy seems to be the most accepted of these techniques. Although there are many published series describing these different cardiac approaches, the lack of prospective, randomized studies comparing conventional and minimally invasive surgery precludes the demonstration of the benefits of the new technique. In spite of this, we think the "J" ministernotomy undoubtedly has aesthetic advantages, smaller complications in patients with respiratory failure, easier repair in case of mediastinitis or osteomyelitis and fewer adhesions in surgical redos.
Revista Espa de Cardiologia 05/2000; 53(4):483-9. · 2.53 Impact Factor
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ABSTRACT: To evaluate our initial experience in the combination of two less invasive procedures for myocardial revascularization, coronary artery bypass grafting without cardiopulmonary bypass and immediate posterior angioplasty, on untreated lesions (hybrid revascularization) as an alternative treatment to conventional surgery in selected patients.
From october 1996 to September 1998, 19 patients received hybrid revascularization. The mean age was 64 (47-76). Two patients underwent urgent surgery. Two patients had left main coronary disease, and 9 three-vessel disease. In general, we considered this procedure for patients with high-risk factors for cardiopulmonary bypass and two or more vessel disease. The internal mammary artery was connected to the left anterior descending artery in all 19 patients. All patients were moved to the hemodynamic ward immediately after surgery in 7 cases and before 48 h in the rest, 24 angioplasties were performed. A mean of 2.6 vessels per patient were revascularized and revascularization was complete in 15 patients (79%).
One patient had perioperative myocardial infarction. There was no hospital mortality. Length of stay in the intensive care unit was 44 h (IQR = 49) and global postoperative stay was 8 days (IQR = 3.5). In the postoperative angiographic study, before the angioplasty, 95% of mammary arteries (CI 95% 74-100%) and 100% of saphenous grafts (CI 95% 59-100%) were patent.
Combined revascularization allows almost complete revascularization, avoiding complications of cardiopulmonary bypass and minimizing surgical aggression. At the same time, it secures the graft of internal mammary artery to left anterior descending artery.
Revista Espa de Cardiologia 11/1999; 52(11):898-902. · 2.53 Impact Factor
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ABSTRACT: Improvement in cardiac surgery techniques has led to a considerable reduction in mortality following surgery of the aorta, dissection of the aorta and for aortic aneurysms. Although there are satisfactory vascular results following surgical repair, morbi-mortality related to neurological complications, both cerebral and spinal, is still very high. Repair of aortic lesions may lead to damage by two main mechanisms: ischemia secondary to prolonged obstruction of the aorta or to neurological lesions due to total circulatory arrest.
After description of the mechanisms leading to cerebral and spinal lesions and the risk factors involved, we discuss methods of vascular protection and other means of neuro-protection, both spinal and cerebral. Of the vascular techniques for spinal protection, the most useful ones are short-circuits, or active or passive shunts, and cardiopulmonary by-pass. Amongst the vascular techniques for cerebral protection we describe total circulatory arrest and methods of anterograde and retrograde cerebral perfusion, and when these may be used. As general measures for nervous system protection, we describe the use of hypothermia and drugs such as corticosteroids, free radical blockers, antagonists of the excitatory amino-acids etc.
In spite of the number of studies done, the extreme sensitivity of the nervous system to ischemia has meant that in few cases have encouraging results been seen. Neurological damage continues to be the main cause of morbi-mortality in patients with dissection or aneurysm of the aorta.
Revista de neurologia 12/1998; 27(159):854-61. · 0.65 Impact Factor
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ABSTRACT: The increase in the mean populational age has increased the number of elderly people eligible for cardiac surgery. The aortic pathology represents the most common valvular pathology, mainly of degenerative etiology. The efficiency of the aortic valve replacement in people aged over 75 years was studied, with evaluation of hospital mortality, survival and functional class (NYHA).
A total of 51 patients (25 males and 26 females, mean age 76.4 years [range: 75-83]) underwent aortic valve replacement from October 1989 to February 1997. The most common condition was aortic stenosis (62.7%), followed by aortic insufficiency (19%) and double aortic lesion (17%). Moreover, 31.3% of patients required also coronary surgery with a mean of 1.1 grafts per patient. In 13.7% of cases surgery on mitral valve was performed (1 commissurotomy, 1 mitral prosthesis, 5 valve prostheses). In 10% of patients the procedure had to be performed on an emergency basis. The functional class of patients prior to surgery was NYHA grade III for 37% and grade IV for 10% of cases. The clinical symptoms corresponded to angor in 15 cases (29.4%) and syncope in four cases (7.8%). In nine patients the left ventricular ejection fraction prior to surgery was below 50%. Aortic bioprostheses were implanted in 86.2% of cases.
The hospital fatality rate was 13.7% (7 cases). In the univariate analysis the following mortality risk factors reached statistical significance: left ventricular ejection fraction prior to surgery below 50%, associated surgery and size of aortic prosthesis. In the multivariate analysis the following risk factors were significant: left ventricular ejection fraction prior to surgery below 50% and associated mitral surgery. The follow-up was performed in 100% of patients, with a mean time of 29.6 months. One patient died during follow-up. The functional class was NYHA grade I in 95.2% of cases. The actuarial survival, including hospital mortality, was 84.2% at 5 years.
Despite a higher mortality in the aortic valve replacement surgery in patients aged over 75 years compared with general population, results, long-term survival and life quality of patients, renders surgery a non refusable first option as therapy for aortic valve pathology in this age group. Nevertheless, avoiding the deterioration of preoperative left ventricular function is imperative, mainly in those cases with concomitant mitral pathology, as both factors significantly contribute to an increase in mortality in this group.
Revista Clínica Española 06/1998; 198(5):289-93. · 2.01 Impact Factor
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ABSTRACT: Cardiopulmonary bypass (CEC) in the surgical treatment of cardiac diseases may cause the appearance of neurological damage of an intensity which varies between minor neuropsychological disorders and global cerebral anoxia. There are two mechanisms for the production of these lesions: ischaemic and embolic. The mortality associated with this type of complication is low, but morbidity may be considerable. The neurological disorders derived from CEC may be classified according to the aetiology and clinical findings. In the first group are included: severe cerebral anoxia, embolic cerebro-vascular accidents, microvascular embolias, lesions of spinal vascularization and lesions of the peripheral nerves. In the second group are: encephalic focal lesions, convulsive crises, lesions of the extra-pyramidal system, alterations in the level of consciousness and neuropsychological disorders.
Quantification of neuronal damage has been attempted by: monitoring cerebral blood flow and neurone metabolism, EEG and study of intra-operative evoked potentials, echography of the carotid, cardiac and ascending aorta, transcranial doppler, fluorescein-angiography and the study of biochemical markers of neuronal and glial damage. Different studies have identified a series of factors which potentiate the risk of neurological lesions following CEC. These are: age, severe carotid disease, aortic atherosclerosis and previous cerebro-vascular haemorrhage, amongst others. An attempt is made to reduce the incidence of neurological complications by: pre-operative evaluation of carotid bruits, hypothermia, careful surgical technique and the use of drugs with a neuroglial protector effect. None of these methods gives sufficiently effective protection to the central nervous system subjected to the changes involved in the use of CEC.
There are still many unknown aspects of neurone pathology in these circumstances, leaving a door open to investigation.
Revista de neurologia 09/1997; 25(144):1278-84. · 0.65 Impact Factor
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Revista Clínica Española 08/1997; 197(7):518-22. · 2.01 Impact Factor
