title: Pressure monitoring during neuroendoscopy: new insights.
abstract: BACKGROUND
  Significant increases in intracranial pressure (ICP) may occur during neuroendoscopic procedures. To detect and prevent serious and sustained increases, ICP should be monitored. At present, controversy exists on the optimal location of the monitoring sensor. Therefore, we conducted an in vitro study to estimate the pressure gradients between the ventricle, the 'gold standard' site, and the rinsing inlet and outlet.
  
  
  METHODS
  A head model and a standard endoscope were used. Rinsing was enforced by using a pressurized infusion bag. Using clinically relevant flow rates, pressure was measured at the rinsing inlet and outlet, in the ventricle, and at the distal end of the rinsing channel using a tip sensor or a capillary tube.
  
  
  RESULTS
  At a flow of 61 ml min(-1), the steady-state pressures measured at the rinsing inlet, in the ventricle, and at the rinsing outlet were 38, 26, and 12 mm Hg, respectively. At 135 ml min(-1), these increased to 136, 89, and 42 mm Hg. Transendoscopic pressure measurements were always within 1 mm Hg of the ventricular pressure.
  
  
  CONCLUSIONS
  During endoscopy, measurements at the rinsing inlet overestimated the ventricular pressure by ∼50 mm Hg during heavy rinsing, whereas measurements at the rinsing outlet underestimated the pressure by ∼50 mm Hg. An electronic tip sensor or a pressure capillary tube placed at the distal end of the lumen of the rinsing channel of the endoscope did not interfere with rinsing flow and produced measurements that were equal to ventricular pressures.
authors.affiliation: Department of Neurosurgery, Ghent University Hospital, Gent, Belgium. frank.dewaele@ugent.be
authors.forename: F
authors.initials: F
authors.lastname: Dewaele
authors.forename: A F
authors.initials: AF
authors.lastname: Kalmar
authors.forename: K
authors.initials: K
authors.lastname: Van Canneyt
authors.forename: H
authors.initials: H
authors.lastname: Vereecke
authors.forename: A
authors.initials: A
authors.lastname: Absalom
authors.forename: J
authors.initials: J
authors.lastname: Caemaert
authors.forename: M M R F
authors.initials: MM
authors.lastname: Struys
authors.forename: D
authors.initials: D
authors.lastname: Van Roost
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008953:Models, Anatomic; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D044582:Neuroendoscopes; D044583:Neuroendoscopy / Q000379:methods*; D007507:Therapeutic Irrigation / Q000379:methods