title: Laparoscopic colon surgery: unreliability of end-tidal CO2 monitoring.
abstract: BACKGROUND
  The relatively good haemodynamic and respiratory tolerance to abdominal CO(2) insufflation has mostly been observed in healthy patients during short-lasting laparoscopic procedures. End-tidal CO(2) pressure (PetCO(2)) has been shown to be a reliable method to assess arterial CO(2) (PaCO(2)) in the absence of cardio-respiratory disease in this setting. However, no study has investigated whether PetCO(2) is accurately related to PaCO(2) during laparoscopic colon surgery. Indeed, these procedures last longer, prolonging the pneumoperitoneum and requiring a Trendelenburg position. The aim of the present study was to measure the PaCO(2)-PetCO(2) difference over time in patients undergoing laparoscopic colon surgery and to determine whether PaCO(2) is reliably assessed by PetCO(2).
  
  
  METHODS
  Forty consecutive patients (ASA I and II) scheduled for laparoscopic colon surgery were anaesthetized and ventilated to obtain a PetCO(2) between 4.0 and 5.5 kPa. After initiation of CO(2) insufflation, PaCO(2) and PetCO(2) were recorded every 30 min during surgery.
  
  
  RESULTS
  No complication was observed during anaesthesia. The mean arterial pressure increased significantly after CO(2) insufflation and remained steady up to the end of pneumoperitoneum. The heart rate remained stable over time. The relation between PaCO(2) and PetCO(2) was not constant among patients and increased over time within the same patients. The R(2) values fluctuated and did not show a constant correlation between PaCO(2) and PetCO(2).
  
  
  CONCLUSIONS
  The correlation between PaCO(2) and PetCO(2) during laparoscopic colon surgery is inconsistent mainly due to inter- and intra-individual variability.
authors.affiliation: Service of Anaesthesiology, University Hospitals, Geneva, Switzerland. Claude-Eric.Klopfenstein@hcuge.ch
authors.forename: C E
authors.initials: CE
authors.lastname: Klopfenstein
authors.forename: E
authors.initials: E
authors.lastname: Schiffer
authors.forename: C M
authors.initials: CM
authors.lastname: Pastor
authors.forename: M
authors.initials: M
authors.lastname: Beaussier
authors.forename: K
authors.initials: K
authors.lastname: Francis
authors.forename: C
authors.initials: C
authors.lastname: Soravia
authors.forename: F R
authors.initials: FR
authors.lastname: Herrmann
mesh_terms: D000704:Analysis of Variance; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D003106:Colon / Q000601:surgery*; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology; D006801:Humans; D010535:Laparoscopy; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010313:Partial Pressure; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects*; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012129:Respiratory Function Tests; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide