title: Time-related changes in hemodynamic parameters and pressure-derived indices of left ventricular function in a porcine model of prolonged pneumoperitoneum.
abstract: BACKGROUND
  Advanced laparoscopic procedures require prolonged pneumoperitoneum. Increased intra-abdominal pressure causes a number of hemodynamic changes including a drop in cardiac output, but it is unclear whether there is a direct effect on cardiac contractility. In this experimental study, we sought to determine whether there is a direct impact of pneumoperitoneum on cardiac contractility. We also examined the time-related changes taking place during the insufflation period.
  
  
  METHODS
  Six young pigs were anesthetized and mechanically ventilated. Pneumoperitoneum was established by insufflating carbon dioxide to a pressure of 15 mmHg and maintained for a period of 180 min. Hemodynamic parameters including left ventricular dP/dT were invasively recorded every 15 min. All hemodynamic changes were statistically evaluated, and parameters were correlated with time.
  
  
  RESULTS
  Cardiac output decreased with insufflation from a baseline of 3.37 +/- 0.34 lt/min and reached the lowest value at 165 min of pneumoperitoneum (2.86 +/- 0.30 l/min; p = 0.023). Systemic vascular resistance (SVR) significantly increased from 2236 +/- 227 dyne/s/cm(5) to a maximum of 3774 +/- 324 dyne/s/cm(5) (p = 0.005). Left ventricular dP/dT maximum did not change significantly with insufflation. The decrease in cardiac output strongly correlated with the increase in SVR (r = -0.949). Time of insufflation correlated with cardiac output (r = -0.762) and dP/dT maximum (r = -0.727).
  
  
  CONCLUSIONS
  Pneumoperitoneum at 15 mmHg negatively affects cardiac output without significantly affecting cardiac contractility. A significant increase in SVR appears to be the driving event for the decreased cardiac output. Prolonged pneumoperitoneum may have an additional negative effect on hemodynamic parameters.
authors.affiliation: Department of Surgery, Yale University School of Medicine, New Haven, CT 06504, USA.
authors.forename: I G
authors.initials: IG
authors.lastname: Kaklamanos
authors.forename: S
authors.initials: S
authors.lastname: Condos
authors.forename: R C
authors.initials: RC
authors.lastname: Merrell
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D009200:Myocardial Contraction; D011028:Pneumoperitoneum, Artificial; D013318:Stroke Volume; D013552:Swine; D013997:Time Factors; D014655:Vascular Resistance