title: Terminal gas velocity during laparoscopy.
abstract: OBJECTIVE
  To assess the effect of port size in relation to laparoscopic gas flow and to determine the terminal velocity of gas flow during insufflation.
  
  
  METHODS
  Analysis and mathematical modeling of gas flow characteristics.
  
  
  METHODS
  University biomedical engineering department.
  
  
  METHODS
  Analytic calculations including Bernoulli's equation to describe gas volumetric flow and velocity as it exits laparoscopic intraabdominal entrance sites.
  
  
  RESULTS
  Mathematical modeling showed that terminal velocity of gas entering the abdomen through needles or trocars reaches a practical limit depending on size and configuration of the gas exit site, amount of turbulence, length of delivery port, and gas flow. Flow rate was evaluated for circles of 2, 5, and 10 mm and annular slots of 0.1- to 0.01-mm thickness.
  
  
  CONCLUSIONS
  Resistance to gas flow increases and gas exiting terminal velocity increases as the effective area of the gas exit site decreases. Depending on the configuration of variable parameters, gas flow can reach 30 m/second.
authors.affiliation: Mercer University, 1400 Coleman Avenue, Macon, GA 31207, USA.
authors.forename: Laura W
authors.initials: LW
authors.lastname: Lackey
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Ott
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D004867:Equipment Design; D005260:Female; D006801:Humans; D007327:Insufflation; D010535:Laparoscopy; D008962:Models, Theoretical; D011028:Pneumoperitoneum, Artificial; D011677:Punctures