title: Blood gas changes in patients undergoing laryngeal microsurgery.
abstract: BACKGROUND
  The aim of this prospective, single-blind study was to assess the variations in the blood levels of PaO(2), PaO(2)/FiO(2), PaCO(2), and acid-base balance of patients undergoing laryngeal microsurgery under general anesthesia using small-bore endotracheal tubes.
  
  
  METHODS
  25 male patients were intubated with endotracheal tubes of 5.5-mm-inner diameter and fifteen female patients were intubated with endotracheal tubes of 5-mm-inner diameter during surgery. PaO(2)/FiO(2), PaO(2), PaCO(2), percentage saturation of O(2) and HCO(3), and pH levels were monitored before surgery and at 15-min intervals during laryngeal microsurgery. Respiratory function's values (dead space, peak inspiratory pressure (PIP) and dynamic compliance) were recorded every 15 min throughout laryngeal microsurgery.
  
  
  RESULTS
  No significant differences were observed between the pre- and intra-operative values of percentage saturation of O(2), PaO(2)/FiO(2) and HCO(3) until 120th min. There was no significant difference in respiratory function's values intraoperatively. Under anesthesia, PaO(2) levels significantly increased when compared with preoperative values. Another significant increase was observed in PaCO(2) levels after the 60th min. However, compared with preoperative values, pH levels significantly decreased under anesthesia at the 105th and 120th min.
  
  
  CONCLUSIONS
  Laryngeal microsurgery under general anesthesia can be performed using small-bore endotracheal tubes. This is not likely to have any adverse effects on a patient's blood gases and acid-base balance unless the operation lasts longer than 105 min.
authors.affiliation: Department of Anesthesiology, Sisli Etfal Training Hospital, Istanbul, Turkey. asurhan@yahoo.com
authors.forename: Surhan Ozer
authors.initials: SO
authors.lastname: Cinar
authors.forename: Berna Uslu
authors.initials: BU
authors.lastname: Coskun
authors.forename: Ugur
authors.initials: U
authors.lastname: Cinar
authors.forename: Melahat Karatmanli
authors.initials: MK
authors.lastname: Erol
authors.forename: Sibel
authors.initials: S
authors.lastname: Oba
authors.forename: Burhan
authors.initials: B
authors.lastname: Dadas
mesh_terms: D000136:Acid-Base Equilibrium; D000293:Adolescent; D000328:Adult; D000768:Anesthesia, General; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation; D007828:Laryngoscopy; D007830:Larynx / Q000601:surgery*; D008297:Male; D008866:Microsurgery; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen