title: Power spectral analysis of heart rate variability during helium pneumoperitoneum: The mechanism of increased cardiac sympathetic activity and its clinical significance.
abstract: BACKGROUND
  Carbon dioxide pneumoperitoneum (PP) is known to induce increased cardiac sympathetic expression. The role of the insufflated gas involved in this mechanism should be elucidated in an attempt to eliminate its possible serious consequences.
  
  
  METHODS
  Twenty-five patients undergoing elective laparoscopic cholecystectomy were prospectively analyzed for cardiac autonomic nervous activity by spectral heart rate variability. In 15 patients, helium was used as CO(2) substitution for abdominal insufflation (study group). Four frequency bands of interest were obtained from the power spectrum of R-R intervals, as well as the ratio between the low and high frequency (LF/HF), using the fast Fourier transformation algorithm to characterize the synergy of both autonomic branches during PP.
  
  
  RESULTS
  Significantly increased values of the power spectrum related to the LF and VLF bands (from 130 to 377 msec(2)/Hz and from 145 to 516 msec(2)/Hz, respectively) were inspected during CO(2) PP, as well as increased LF/LH ratio (2.1). Using helium as CO(2) substitution has eliminated the significant changes in the power spectrum that reflect increased cardiac sympathetic activity.
  
  
  CONCLUSIONS
  The elimination of sympathetic predominance by helium PP indicates the central role of CO(2) in establishing this phenomena. Considering this information and its other known advantages, helium should be considered for use during prolonged laparoscopic procedures for high-risk patients.
authors.affiliation: Department of Surgery, Western Galilee Hospital, Nahariya, 22100, Israel. amitai@netvision.net.il
authors.forename: A
authors.initials: A
authors.lastname: Bickel
authors.forename: E
authors.initials: E
authors.lastname: Kukuev
authors.forename: O
authors.initials: O
authors.lastname: Popov
authors.forename: S
authors.initials: S
authors.lastname: Ivry
authors.forename: N
authors.initials: N
authors.lastname: Roguin
authors.forename: M
authors.initials: M
authors.lastname: Yahalom
authors.forename: A
authors.initials: A
authors.lastname: Eitan
mesh_terms: D000328:Adult; D000368:Aged; D017081:Cholecystectomy, Laparoscopic; D005260:Female; D006334:Heart Function Tests; D006339:Heart Rate / Q000187:drug effects*; D006371:Helium / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011028:Pneumoperitoneum, Artificial / Q000379:methods; D011446:Prospective Studies; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D006371:Helium