1 Department of Critical Care Medicine, Instituto Nacional de Cancerología, Mexico City, Mexico.
2 Department of Critical Care Medicine, Hospital Especialidades Centro Médico Nacional La Raza, Mexican Institute of Social Security, Mexico City, Mexico.
3 Department of Internal Medicine, General Zone Hospital No. 47, Mexican Institute of Social Security, Mexico City, Mexico.
4 Department of Critical Care Medicine, Fundación Clínica Médica Sur, Mexico City, Mexico.
5 Department of Critical Care Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.