title: Pulse pressure variation as a tool to detect hypovolaemia during pneumoperitoneum.
abstract: BACKGROUND
  Pulse pressure variation (DeltaPP) and systolic pressure variation (SPV) induced by mechanical ventilation have been proposed to detect hypovolaemia and guide fluid therapy. During laparoscopic surgery, chest compliance is decreased by pneumoperitoneum. This may affect the value of SPV and DeltaPP as indicators of intravascular volume status. Thereby, we investigated the effects of pneumoperitoneum and hypovolaemia on SPV and DeltaPP.
  
  
  METHODS
  We measured DeltaPP, SPV and the inspiratory (Deltaup) and expiratory (Deltadown) components of SPV, at baseline, during pneumoperitoneum, during pneumoperitoneum and hypovolaemia and after the return to baseline conditions, in 11 mechanically ventilated rabbits. Pneumoperitoneum was induced by inflating the abdomen with carbon dioxide, and hypovolaemia was induced by controlled haemorrhage.
  
  
  RESULTS
  Pneumoperitoneum induced an increase in SPV from 8.5 +/- 1.6 to 13.3 +/- 2.6 mmHg (+56%, P < 0.05) as a result of an increase in Deltaup from 2.0 +/- 1.0 to 6.7 +/- 2.1 mmHg (+236%, P < 0.05), but no significant change in Deltadown, nor in DeltaPP. Haemorrhage induced a significant (P < 0.05) increase in SPV from 13.3 +/- 2.6 to 19.9 +/- 3.7 mmHg (+50%), in Deltadown from 6.6 +/- 3.3 to 14.0 +/- 4.9 mmHg (+112%) and in DeltaPP from 11.1 +/- 4.8 to 24.9 +/- 9.8% (+124%) but no change in Deltaup. All parameters returned to baseline values after blood re-infusion and abdominal deflation.
  
  
  CONCLUSIONS
  SPV is modified by haemorrhage but it is also influenced by pneumoperitoneum. In contrast, DeltaPP is modified by haemorrhage but not by pneumoperitoneum. These findings suggest that DeltaPP should be used preferentially instead of SPV to detect hypovolaemia and guide fluid therapy during laparoscopic surgery.
authors: Clinical Investigation Laboratory L. I. M. 8 School of Medicine-University of Sao Paulo, Sao Paulo, Brazil. fernandobli@uol.com.br
authors: F
authors: F
authors: Bliacheriene
authors: S B
authors: SB
authors: Machado
authors: E B
authors: EB
authors: Fonseca
authors: D
authors: D
authors: Otsuke
authors: J O C
authors: JO
authors: Auler
authors: F
authors: F
authors: Michard
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D020896:Hypovolemia / Q000175:diagnosis*; D010535:Laparoscopy; D016343:Monitoring, Intraoperative; D011028:Pneumoperitoneum, Artificial; D011817:Rabbits; D013318:Stroke Volume / Q000502:physiology*