title: High-intensity transient signals during laparoscopic surgery in children.
abstract: BACKGROUND
  Laparoscopic interventions in children gain increasing popularity. Pneumoperitoneum as applied during laparoscopic surgery can induce gas emboli formation, but it is unclear whether this is associated with cerebral embolic events. To investigate the hypothesis that pneumoperitoneum causes cerebral emboli in children, the number and intensity of high-intensity transient signals (HITS) detected using transcranial Doppler ultrasonography were assessed before and after induction of pneumoperitoneum.
  
  
  METHODS
  Twenty children were monitored during laparoscopic surgery. General anaesthesia was performed using sevoflurane and sufentanil or alfentanil. Pressure-controlled ventilation was adapted to maintain end-tidal Pco(2) (Pe'(co(2))) between 4.7 and 6.0 kPa. Baseline measurement of HITS rate, cerebral blood flow velocity, and mean arterial pressure (MAP) were recorded during steady-state anaesthesia before skin incision and during pneumoperitoneum with intra-abdominal pressure of 1.6-2.0 kPa applied using CO(2).
  
  
  RESULTS
  In 14 children (70%), HITS were detected during baseline and pneumoperitoneum. Three additional children (15%) developed HITS during pneumoperitoneum only and another three children (15%) presented no HITS during the investigation period. MAP and cerebral blood flow velocity increased with pneumoperitoneum.
  
  
  CONCLUSIONS
  HITS are present in 70% of paediatric surgical patients under balanced anaesthesia before surgical interventions. Pneumoperitoneum further increased the occurrence of HITS.
authors.affiliation: Department of Anaesthesiology, University Medical Centre of the Johannes Gutenberg-University Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany. schrammp@uni-mainz.de
authors.forename: P
authors.initials: P
authors.lastname: Schramm
authors.forename: K
authors.initials: K
authors.lastname: Engelhard
authors.forename: A
authors.initials: A
authors.lastname: Scherhag
authors.forename: F
authors.initials: F
authors.lastname: Schier
authors.forename: C
authors.initials: C
authors.lastname: Werner
mesh_terms: D001783:Blood Flow Velocity; D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D020766:Intracranial Embolism / Q000000981:diagnostic imaging / Q000209:etiology*; D007431:Intraoperative Complications / Q000000981:diagnostic imaging*; D010535:Laparoscopy / Q000009:adverse effects*; D008297:Male; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects*; D017585:Ultrasonography, Doppler, Transcranial