Aproximación al valor de la caminata de 6 minutos para pronosticar deterioro clínico en pacientes con diagnóstico de hipertensión pulmonar (HTP) arterial a la altura de Bogotá

Abstract

Pulmonary arterial hypertension (PAHT) is a progressive and debilitating disease that has partially transformed from devastating to inevitably fatal in recent decades. Within the internationally accepted goals for the follow-up of this group of patients, the 6-minute walk has been established as one of the most critical tests. It is currently the most widely used exercise test in the world in the different HTPA centers. Most have performed on patients in cities less than 500m above sea level. It is unknown if these should be the same parameters to be considered in the towns of great heights, that is, above 2500mt above sea level. Objective: Approximate the value of the 6-minute walk to predict clinical deterioration in patients diagnosed with pulmonary arterial hypertension (PAHT) at the height of Bogotá Methods: Study with a quantitative and descriptive approach of a retrospective cohort. All patients from the Fundacion Neumoloica from Bogotá with pulmonary arterial hypertension diagnosed by cardiac catheterization residing in Bogotá were chosen. A demographic analysis of the population and disease status, classification, type of treatment, and oxygen use was performed. Contingency tables were used to evaluate the association and differences of the clinical deterioration variable with the delta of oxygen saturation during walking, heart rate recovery, and meters walked. A subgroup of analysis was performed according to the use or not of oxygen during the walk to determine the difference in its association with the clinical deterioration outcome. Results: 134 patients diagnosed with HTPA with a 6-minute walk performed at Fundacion Neumologica Colombiana were analyzed. Of these, the majority were women (82.1%) with an average age of 46. Within the classification, the most frequent etiology was congenital heart disease (49%), followed by idiopathic (32%). Most of this population was at intermediate risk for pulmonary hypertension (52.2%). It was identified that 41% of the patients evaluated required the use of supplemental oxygen during the first walk. 23.9% of the patients assessed presented some clinical deterioration. A statistically significant association was found between clinical deterioration, and the distance in meters walked (p = 0.05). The patients who presented clinical deterioration had a median of 448 meters walked, while those who did not have this deterioration presented a median of 509 meters. Finally, it was found that of the patients who used oxygen during the walk, 29.4% presented clinical deterioration, while of those who did not use it, only 13.5% presented deterioration; however, no significant associations were found between the variables (heart rate recovery, clinical deterioration, oxygen saturation delta, and distance in meters walked). Conclusions: This study shows differences in meters in the 6-minute walk test in patients with HTPA around Bogotá compared to international reference studies. Specifically, patients at the height of Bogotá walk more meters despite the same disease severity compared to the other records corresponding to patients who live in cities not classified as high altitudes. The need to be replicated in other centers around Bogotá and to increase the sample size to establish specific prognostic cut-off points is suggested. The requirement for oxygen uses in patients with HTPA at the height of Bogotá is lower compared to the international reference cohorts; even despite hypobaric hypoxemia due to altitude and the same degree of severity of the disease, these cohorts are represented in their entirety by patients who live in cities not classified as high altitudes. The differences found in the meters walked and the need for oxygen for patients with the same disease, but living at the height of Bogotá, strongly suggests that the hypobaric hypoxemia of the altitude affects the behavior of the disease with different clinical outcomes for the values of meters walked that internationally would have cut-off points very different from those found in the study population at the height of Bogotá.