title: Influence of different pressures of pneumoperitoneum on the autonomic system function during laparoscopy.
abstract: The effects of different pressure values of pneumoperitoneum on the activity of the autonomic nervous system (ANS) have not been investigated in detail. In this prospective study, 20 patients qualified for laparoscopic cholecystectomy were randomised to either low-pressure (LP = 7 mmHg) or standard-pressure (SP = 12 mmHg) pneumoperitoneum groups, 10 patients each. The anesthesia was induced with fentanyl and thiopental and maintained with isoflurane. Ventilation was mechanically controlled (18 breaths per minute, end-tidal CO2 30-35 mmHg, instant capnometer monitoring). Intraabdominal pressure was maintained automatically by a CO2 insufflator. Patient were kept in a horizontal position. The ANS was evaluated by heart rate variability (HRV) analysis (POSTER ECG 2002 System) measured intraoperatively in three recordings of 5 minutes each: in awake patient, after induction of general anesthesia, and after creation of pneumoperitoneum. Power spectral analysis of HRV was applied, the low-frequency (LF = 0.05-0.15 Hz) and high frequency (HF = 0.15-0.45 Hz) spectral density of the HRV were analysed using the Fast Fourier Transform algorithm. The appropriate statistical analysis of data was performed. LF density decreased at the anesthetized stage and increased at the insufflated stage in both groups (p < 0.01). LP resulted in lower sympathetic activation than SP pneumoperitoneum (LF: 68.12 +/- 6.56 nu vs. 78.26 +/- 5.43 nu, p < 0.01; HF: 24 +/- 2.48 nu vs. 15.56 +/- 2.54 nu, p < 0.05).
  
  
  CONCLUSIONS
  pneumoperitoneum leads to sympathetic activation of the ANS. LP in comparison to SP pneumoperitoneum with carbon dioxide results in significantly decreased sympathetic activation during laparoscopy.
authors.affiliation: College of Medicine of Jagiellonian University, ul. Pradnicka 37, 31-202 Kraków, Poland. marbar@mp.pl
authors.forename: Marcin
authors.initials: M
authors.lastname: Barczyński
authors.forename: Roman Maria
authors.initials: RM
authors.lastname: Herman
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D015992:Body Mass Index; D017081:Cholecystectomy, Laparoscopic / Q000379:methods*; D002769:Cholelithiasis / Q000601:surgery; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011028:Pneumoperitoneum, Artificial / Q000379:methods*; D011312:Pressure; D011446:Prospective Studies