title: Apnea-induced hemoglobin desaturation during one-lung vs two-lung ventilation.
abstract: OBJECTIVE
  To compare the rate of apnea-induced hemoglobin desaturation during one-lung ventilation (OLV) vs. two-lung ventilation (TLV) in patients undergoing thoracic surgery.
  
  
  METHODS
  Six patients undergoing thoracotomy or thoracoscopy were included. Each patient served as his/her own control. The lungs were ventilated with oxygen 100% using TLV, followed after 20-30 min by OLV and the resultant PaO2 was measured. Apnea was then induced following the two techniques of ventilation, and the times for every 1% decrease in hemoglobin saturation from 100% to 95%, as monitored by pulse oximetry, were recorded. The times for every 1% decrease in the saturation were compared in the two groups.
  
  
  RESULTS
  The mean PaO2 value following TLV (445+/-99 mm Hg) was higher than the mean PaO2 following OLV (156+/-18 mm Hg). Also, the mean time for subsequent apnea induced hemoglobin desaturation from SpO2 100% to 95% following TLV was twice the time of desaturation following OLV (6.3+/-1.2 min vs. 3.2+/-0.5 min, P<0.05).
  
  
  CONCLUSIONS
  Hemoglobin desaturation occurs more rapidly during apnea following OLV than TLV. The rapid desaturation may be attributed to the decrease of FRC, associated with an increased transpulmonary shunting. The results suggest that two-lung ventilation with oxygen 100% provides a greater safety margin than one-lung ventilation with oxygen 100% whenever ventilation is interrupted.
authors.affiliation: Department of Anesthesiology, American University of Beirut, Lebanon. abaraka@aub.edu.lb
authors.forename: A
authors.initials: A
authors.lastname: Baraka
authors.forename: M
authors.initials: M
authors.lastname: Aouad
authors.forename: S
authors.initials: S
authors.lastname: Taha
authors.forename: M
authors.initials: M
authors.lastname: El-Khatib
authors.forename: N
authors.initials: N
authors.lastname: Kawkabani
authors.forename: A
authors.initials: A
authors.lastname: Soueidi
mesh_terms: D000328:Adult; D000368:Aged; D001049:Apnea / Q000097:blood*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D012121:Respiration, Artificial; D013906:Thoracoscopy; D013908:Thoracotomy
chemical_list: D006454:Hemoglobins