1. Department of Anesthesiology, Riga Stradins University, LV-1007 Riga, Latvia
2. Laboratory of Biophotonics, Institute of Atomic Physics and Spectroscopy, University of Latvia, LV-1004 Riga, Latvia
3. Residency Development Department, University of Latvia, LV-1004 Riga, Latvia
4. Department of Human and Animal Physiology, Faculty of Biology, University of Latvia, LV-1004 Riga, Latvia