Abstract The first anesthetic machines appeared following their public demonstration by Morton in 1846. These initial devices were simple inhalers based on the evaporation of the anesthetic agent. Their main problem was the loss of effectiveness with cooling. More complex inhalers were subsequently developed, in which the main difference was the possibility to provide more than one agent. Moreover, the concentration of the inhaled anesthetic was regulated for greater efficiency. At the beginning of the twentieth century, gas machines emerged, allowing the application of an anesthetic flow independent of the patient’s inspiratory effort. These machines incorporated technological advances such as flow meters, carbon dioxide absorption systems and fine adjustment vaporizers. In this period, in the field of thoracic surgery, intraoperative artificial ventilation began to be employed, which helped overcome the problem of pneumothorax associated with open pleura by applying positive pressure. From the 1930s, the gas machines were fitted with a ventilator, and by the 1950s this had become a basic component of the anesthesia system. Later still, in the 1980s, alarm and monitoring systems were incorporated, giving rise to the current generation of workstations.

The aim of mechanical ventilation is to substitute physiological respiratory function. The boom of mechanical ventilation came during the XVIII century with the development of Reanimation Societies in Europe, who promoted the use of positive pressure ventilation modes. This type of ventilation caused new complications due to excessive positive pressure in the airway. Therefore, during the XIX century negative pressure ventilation predominated, which became essential during the second half of the 19th century and first half of the 20th century. Positive pressure ventilation was relegated to operating rooms until 1952, when it was imposed over negative pressure ventilation during the Copenhagen polio epidemic. Björn Ibsen contributed significantly to this change of ventilation paradigm, which led to the latest ventilation strategies and the development of the actual intensive care units.

BACKGROUND: Outpatient surgery initially came into being and further developed as a result of the progressive increase in the demand and in hospital expenses. Although it has afforded the possibility of lowering the cost per procedure and of improving the efficiency of the hospitals by maintaining the degrees of patient satisfaction and safety, it has also made it necessary to question the customary activity indicators. This had led us to assess the outpatient surgery units of the recently-opened Algeciras Hospital based on the customary system of payment in other countries, the Related Diagnostic Groups (RDG’s). METHODS: Descriptive study regarding 3,051 surgical procedures performed on a scheduled basis in 1997 (not including the minor surgery using a local anesthetic), using as a source of information the minimum basic set of data for hospital discharge, obtaining and analyzing the RDG’s. The hospital stays avoided based on the average stay of those patients admitted for the same RDG within the time period under study have been calculated. RESULTS: Major surgery performed on an outpatient basis afforded the possibility of an overall replacement percentage of 50.4% (33.3% of all of the patients who underwent surgery on a scheduled basis, that is, 4.1% of all of this Hospital’s admissions), which meant an savings of 2,112 hospital stays. The most frequent RDG’s having the greatest impact on stays avoided were the surgical procedures performed on the crystalline lens and the scraping or conization procedures performed for reasons other than malignant neoplasia. The readmission rate was 1.5%. CONCLUSIONS: The overall replacement rate obtained by this major outpatient surgery unit is considered to be acceptable, although it must increase within the next few years. We found differences in the spread of the processes dealt with as compared to other units in our environment, this being explainable due to the difficulties involved in starting up surgery of these characteristics.

FUNDAMENTO: La cirugía ambulatoria surge y se desarrolla como consecuencia del aumento progresivo de la demanda y del gasto sanitario. Aunque ha permitido reducir el coste por proceso y mejorar la eficacia de los hospitales, manteniendo los niveles de satisfacción y seguridad del paciente, también ha obligado a cuestionar los indicadores de actividad habituales; esto nos ha llevado a evaluar la unidad de cirugía ambulatoria del hospital de Algeciras, de reciente creación, en base al sistema de pago habitual en otros países, los Grupos Relacionados de Diagnóstico (GRD). MÉTODO: Estudio descriptivo sobre las 3.051 intervenciones quirúrgicas realizadas de forma programada durante 1997 (exceptuando la cirugía menor con anestesia local), utilizando como fuente de información el conjunto mínimo básico de datos al alta hospitalaria, obteniéndose y analizando los grupos relacionados de diagnóstico. Se han calculado las estancias evitadas en base a la estancia media de los pacientes ingresados por el mismo grupos relacionados de diagnóstico en el período de tiempo de estudio. RESULTADOS: La cirugía mayor ambulatoria permitió un porcentaje de sustitución global del 50,4% (33.3 % de todos los pacientes intervenidos de forma reglada; 4,1 % sobre el total de ingresos del hospital), lo que supuso un ahorro de 2.112 estancias hospitalarias. Los grupos relacionados de diagnóstico más frecuentes y con mayor impacto en estancias evitadas fueron los procedimientos quirúrgicos del cristalino y los legrados uterinos o conizaciones realizados por causa distinta a neoplasia maligna. La tasa de reingresos fue del 1,5 %. CONCLUSIONES: El porcentaje de sustitución global obtenido por esta unidad de cirugía mayor ambulatoria es considerado aceptable, si bien, debe incrementarse en los próximos años. Encontramos diferencias en la distribución de los procesos atendidos en relación a otras unidades de nuestro entorno, explicables por las dificultades que supone comenzar una cirugía de estas características.

BACKGROUND: Outpatient surgery initially came into being and further developed as a result of the progressive increase in the demand and in hospital expenses. Although it has afforded the possibility of lowering the cost per procedure and of improving the efficiency of the hospitals by maintaining the degrees of patient satisfaction and safety, it has also made it necessary to question the customary activity indicators. This had led us to assess the outpatient surgery units of the recently-opened Algeciras Hospital based on the customary system of payment in other countries, the Related Diagnostic Groups (RDG’s). METHODS: Descriptive study regarding 3,051 surgical procedures performed on a scheduled basis in 1997 (not including the minor surgery using a local anesthetic), using as a source of information the minimum basic set of data for hospital discharge, obtaining and analyzing the RDG’s. The hospital stays avoided based on the average stay of those patients admitted for the same RDG within the time period under study have been calculated. RESULTS: Major surgery performed on an outpatient basis afforded the possibility of an overall replacement percentage of 50.4% (33.3% of all of the patients who underwent surgery on a scheduled basis, that is, 4.1% of all of this Hospital’s admissions), which meant an savings of 2,112 hospital stays. The most frequent RDG’s having the greatest impact on stays avoided were the surgical procedures performed on the crystalline lens and the scraping or conization procedures performed for reasons other than malignant neoplasia. The readmission rate was 1.5%. CONCLUSIONS: The overall replacement rate obtained by this major outpatient surgery unit is considered to be acceptable, although it must increase within the next few years. We found differences in the spread of the processes dealt with as compared to other units in our environment, this being explainable due to the difficulties involved in starting up surgery of these characteristics.

FUNDAMENTO: La cirugía ambulatoria surge y se desarrolla como consecuencia del aumento progresivo de la demanda y del gasto sanitario. Aunque ha permitido reducir el coste por proceso y mejorar la eficacia de los hospitales, manteniendo los niveles de satisfacción y seguridad del paciente, también ha obligado a cuestionar los indicadores de actividad habituales; esto nos ha llevado a evaluar la unidad de cirugía ambulatoria del hospital de Algeciras, de reciente creación, en base al sistema de pago habitual en otros países, los Grupos Relacionados de Diagnóstico (GRD). MÉTODO: Estudio descriptivo sobre las 3.051 intervenciones quirúrgicas realizadas de forma programada durante 1997 (exceptuando la cirugía menor con anestesia local), utilizando como fuente de información el conjunto mínimo básico de datos al alta hospitalaria, obteniéndose y analizando los grupos relacionados de diagnóstico. Se han calculado las estancias evitadas en base a la estancia media de los pacientes ingresados por el mismo grupos relacionados de diagnóstico en el período de tiempo de estudio. RESULTADOS: La cirugía mayor ambulatoria permitió un porcentaje de sustitución global del 50,4% (33.3 % de todos los pacientes intervenidos de forma reglada; 4,1 % sobre el total de ingresos del hospital), lo que supuso un ahorro de 2.112 estancias hospitalarias. Los grupos relacionados de diagnóstico más frecuentes y con mayor impacto en estancias evitadas fueron los procedimientos quirúrgicos del cristalino y los legrados uterinos o conizaciones realizados por causa distinta a neoplasia maligna. La tasa de reingresos fue del 1,5 %. CONCLUSIONES: El porcentaje de sustitución global obtenido por esta unidad de cirugía mayor ambulatoria es considerado aceptable, si bien, debe incrementarse en los próximos años. Encontramos diferencias en la distribución de los procesos atendidos en relación a otras unidades de nuestro entorno, explicables por las dificultades que supone comenzar una cirugía de estas características.