title: Effect of age on pulmonary gas exchange during laparoscopy in the Trendelenburg lithotomy position.
abstract: BACKGROUND
  Physiological changes in respiratory mechanics caused by aging may lead to a deterioration in pulmonary gas exchange, an increase in the alveolar-arterial oxygen gradient [(A-a)D(O2)] and a difference between the arterial carbon dioxide (CO(2)) tension (P(a)(CO(2))) and expired end-tidal CO(2) tension (P(ET)(CO(2))) [P((a-ET))(CO(2))] during laparoscopy in the Trendelenburg lithotomy position (TLP).
  
  
  METHODS
  The subjects were 51 gynecologic patients. Pressure-controlled ventilation was used to maintain P(ET)(CO(2)), measured by the side stream method, within the range 4-4.67 kPa. During laparoscopy with CO(2) insufflation in TLP, the tidal volume was increased to keep P(ET)(CO(2)) within +/- 20% of the pre-insufflation value. The subjects were divided into three groups by age: young group (< 45 years); middle-aged group (45-64 years); and elderly group ( > or = 65 years).
  
  
  RESULTS
  Before pneumoperitoneum (PPN), significant differences were found between the young and elderly groups in the arterial oxygen tension (P(a)(O(2))), (A-a)D(O(2)), P(a)(CO(2)) and P((a-ET))(CO(2)). In all groups, the peak inspiratory pressure and P(a)(CO(2)) increased progressively during PPN in TLP. P((a-ET))(CO(2)) increased gradually after starting CO(2) insufflation in TLP only in the elderly group.
  
  
  CONCLUSIONS
  An increase in P((a-ET))(CO(2)) was seen during PPN in TLP in the elderly group. With CO(2) insufflation in TLP, the setting of mechanical ventilation based on the value of P(ET)(CO(2)) (measured by the side stream method) should be determined with caution in elderly patients.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Asahikawa Medical College, Hokkaido, Japan. osamu@asahikawa-med.ac.jp
authors.forename: O
authors.initials: O
authors.lastname: Takahata
authors.forename: T
authors.initials: T
authors.lastname: Kunisawa
authors.forename: M
authors.initials: M
authors.lastname: Nagashima
authors.forename: K
authors.initials: K
authors.lastname: Mamiya
authors.forename: K
authors.initials: K
authors.lastname: Sakurai
authors.forename: S
authors.initials: S
authors.lastname: Fujita
authors.forename: K
authors.initials: K
authors.lastname: Fujimoto
authors.forename: H
authors.initials: H
authors.lastname: Iwasaki
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006339:Heart Rate; D006801:Humans; D001239:Inhalation; D007327:Insufflation; D010535:Laparoscopy; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000097:blood; D011187:Posture; D016683:Supine Position
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen