title: Cerebral tissue oxygen saturation values in volunteers and patients in the lateral decubitus and beach chair positions: a prospective observational study.
abstract: BACKGROUND
  The objective of this study was to describe changes in cerebral tissue oxygen saturation (SctO2) due to changes in body position in healthy volunteers and in patients undergoing surgery under general anesthesia in the beach chair position (BCP) and lateral decubitus position (LDP).
  
  
  METHODS
  In this prospective observational study, SctO2 was measured in 85 awake volunteers serially positioned every 15 min, beginning with the supine position (SP) and followed by the beach chair, supine, and lateral decubitus positions. Cerebral tissue oxygen saturation was also measured supine and in either the BCP or the LDP in 195 patients (according to surgical preference) undergoing elective arthroscopic shoulder surgery. We measured the lowest stable SctO2 values in each position as well as changes in blood pressure and heart rate.
  
  
  RESULTS
  In healthy volunteers, the median (interquartile range [IQR]) lowest stable SctO2 value in the SP was 69 [66-71] %. A change in position to the BCP caused a small but statistically significant decrease in the median [IQR] lowest SctO2 value to 67 [65-70] % (P = 0.028 compared with baseline). This decrease was associated with an increase in median [IQR] arterial pressure from 83 [78-88] mmHg in the SP to 85 [81-93] mmHg in the BCP (P < 0.001 compared with baseline). In patients undergoing surgery in the BCP, the median [IQR] lowest stable SctO2 value was 55 [51-59] %, which was significantly lower (P < 0.001) than the median [IQR] lowest SctO2 value in patients in the LDP (66 [62-69] %). More patients in the BCP group (57%) showed SctO2 values ≤ 55% and/or a decrease of ≥ 20% from baseline (57%) compared with the LDP group (5% and 6%, respectively; P < 0.001 for each comparison).
  
  
  CONCLUSIONS
  More than 55% of patients undergoing arthroscopic shoulder surgery in the BCP experience cerebral desaturation events. In volunteers without anesthesia, no desaturation events were observed. The clinical importance of these findings needs further investigation.
authors: Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium. ingrid_meex@hotmail.com.|Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium. ingrid_meex@hotmail.com.
authors: Ingrid
authors: I
authors: Meex
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Joris
authors: J
authors: Vundelinckx
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Klaas
authors: K
authors: Buyse
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Francis
authors: F
authors: Deburggraeve
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Stephanie
authors: S
authors: De Naeyer
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Veerle
authors: V
authors: Desloovere
authors: Department of Orthopedic Surgery, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Ludwig
authors: L
authors: Anné
authors: Department of Orthopedic Surgery, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Jan
authors: J
authors: Truijen
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Margot
authors: M
authors: Vander Laenen
authors: Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: René
authors: R
authors: Heylen
authors: Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium.|Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Cathy
authors: C
authors: De Deyne
authors: Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium.|Department of Anesthesiology, Intensive care and Emergency Medicine and Pain Therapy, Ziekenhuis Oost-Limburg, Schiepse Bos 6, 3600, Genk, Belgium.
authors: Frank
authors: F
authors: Jans
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General / Q000379:methods; D001182:Arthroscopy / Q000379:methods*; D001794:Blood Pressure / Q000502:physiology; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D056888:Patient Positioning; D011187:Posture; D011446:Prospective Studies; D012785:Shoulder Joint / Q000601:surgery*; D016683:Supine Position; D055815:Young Adult
chemical_list: D010100:Oxygen