[1] Umea Univ, Dept Surg & Perioperat Sci, Anesthesiol & Intens Care Med, S-90187 Umea, Sweden
[2] Umea Univ, Dept Surg & Perioperat Sci, Anesthesiol & Intens Care Med Sunderbyn, Umea, Sweden
[3] Lulea Univ Technol, Dept Hlth Educ & Technol, Div Nursing & Med Technol, Lulea, Sweden
[4] Umea Univ, Dept Surg & Perioperat Sci, Anesthesiol & Intens Care Med Sundsvall, Umea, Sweden