title: Value of Cushing reflex as warning sign for brain ischaemia during neuroendoscopy.
abstract: BACKGROUND
  During an endoscopic neurosurgical procedure a sudden increase in intracranial pressure may occur at any time. We present a prospective study of haemodynamic changes during such procedures.
  
  
  METHODS
  Physiological data were recorded during the whole operative procedure in 17 consecutive patients who underwent an endoscopic neurosurgical procedure under general anaesthesia. Monitoring included invasive blood pressure, intracranial pressure, electrocardiogram, end-expired carbon dioxide, pulse oximetry and heart rate. Pressure and ECG waveforms were recorded at 100 Hz and evaluated in a subsequent offline analysis.
  
  
  RESULTS
  In almost every case, the occurrence of hypertension and tachycardia was clearly the result of an increase in intracranial pressure. Also, a Cushing reflex developed in almost every case where the cerebral perfusion pressure dropped below 15 mm Hg. The occurrence of bradycardia was not systematically associated with a low cerebral perfusion pressure.
  
  
  CONCLUSIONS
  In this study, we describe the haemodynamic effects of increased intracranial pressure during endoscopic neurosurgical procedures and their respective sequence of events at high temporal resolution. Although most clinicians rely on the occurrence of bradycardia to diagnose intracranial hypertension during endoscopic neurosurgical procedures, we show that a simultaneous onset of hypertension and tachycardia is a better indicator of impaired brain perfusion. Waiting for a persistent bradycardia to alert the surgeon during endoscopic neurosurgical procedures could allow severe bradycardia or even asystole to develop.
authors.affiliation: Department of Anaesthesia, Ghent University Hospital, Ghent, Belgium. alain.kalmar@Ugent.be
authors.forename: A F
authors.initials: AF
authors.lastname: Kalmar
authors.forename: J
authors.initials: J
authors.lastname: Van Aken
authors.forename: J
authors.initials: J
authors.lastname: Caemaert
authors.forename: E P
authors.initials: EP
authors.lastname: Mortier
authors.forename: M M R F
authors.initials: MM
authors.lastname: Struys
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001794:Blood Pressure; D001919:Bradycardia / Q000209:etiology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology; D002560:Cerebrovascular Circulation; D002648:Child; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007223:Infant; D019586:Intracranial Hypertension / Q000150:complications / Q000175:diagnosis; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D044583:Neuroendoscopy / Q000009:adverse effects*; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D013610:Tachycardia / Q000209:etiology; D014696:Ventriculostomy / Q000009:adverse effects