title: Effect of CO(2) pneumoperitoneum on ventilation-perfusion relationships during laparoscopic cholecystectomy.
abstract: BACKGROUND
  Previous studies have shown that pneumoperitoneum transiently reduces venous admixture as assessed by a calculation based on the shunt formula, and increases arterial oxygen tension (PaO(2)) in patients without heart or lung disease. The aim of the present study was to further explore the relationship between ventilation-perfusion (V(A)/Q) before and during pneumoperitoneum by using the multiple inert gas technique.
  
  
  METHODS
  Nine patients without heart or lung disease (ASA I), with a mean age of 42 years, scheduled for laparoscopic cholecystectomy were included. After premedication and induction of anaesthesia, radial artery and pulmonary artery catheters were introduced percutaneously. The V(A)Q relationships were evaluated by the multiple inert gas elimination technique before and during pneumoperitoneum to obtain a direct measure of the pulmonary shunt.
  
  
  RESULTS
  Induction of pneumoperitoneum decreased the pulmonary shunt from 5.8 (4.5) to 4.1 (3.2)% (P<0.05) and increased PaO(2) from 21.7 (5.9) to 24.7 (4.8) kPa (P<0.01). During surgery, the shunt increased from 3.2 (2.8) to 5.2 (3.4)% to the same level as before pneumoperitoneum induction. No area with low V(A)Q was seen. Dead space ventilation amounted to 20.0 (1.2)% in the supine position and did not change during the investigation.
  
  
  CONCLUSIONS
  In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg causes a transient reduction of the pulmonary shunt. The mechanisms underlying the present finding remain to be elucidated.
authors.affiliation: Department of Anaesthesiology, Huddinge University Hospital, Stockholm, Sweden. lena.anderson@anaesth.hs.sll.se
authors.forename: L
authors.initials: L
authors.lastname: Andersson
authors.forename: L
authors.initials: L
authors.lastname: Lagerstrand
authors.forename: A
authors.initials: A
authors.lastname: Thörne
authors.forename: A
authors.initials: A
authors.lastname: Sollevi
authors.forename: L-A
authors.initials: LA
authors.lastname: Brodin
authors.forename: S
authors.initials: S
authors.lastname: Odeberg-Wernerman
mesh_terms: D000328:Adult; D000758:Anesthesia; D001810:Blood Volume / Q000502:physiology; D002245:Carbon Dioxide; D002404:Catheterization; D017081:Cholecystectomy, Laparoscopic / Q000009:adverse effects*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000097:blood; D008297:Male; D008875:Middle Aged; D005741:Noble Gases; D011027:Pneumoperitoneum / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D014692:Ventilation-Perfusion Ratio / Q000502:physiology*
chemical_list: D005741:Noble Gases; D002245:Carbon Dioxide