title: Detection and differentiation of cerebral microemboli in patients undergoing major orthopaedic surgery using transcranial Doppler ultrasound.
abstract: Cerebral microemboli (ME) are frequently generated during orthopaedic surgery and may impair cerebral integrity. However, the nature of cerebral ME, being either of solid or gaseous origin, is poorly investigated. Our primary aim was to determine both the frequency and nature of cerebral ME in generally anaesthetised patients undergoing major orthopaedic surgery.
  
  
  
  Fifty patients (hip/knee/shoulder prosthesis, spine surgery) were enrolled. Cerebral ME and cerebral blood flow velocity (CBFV) were determined in both middle cerebral arteries for 15 min preoperatively and postoperatively, using transcranial Doppler ultrasound. Cerebral tissue oxygen index, determined by near-infrared spectroscopy, was further examined. Statistical analysis was carried out using the Wilcoxon matched-pairs signed-ranks test (median (25 th ; 75 th percentile), P  < 0.05).
  
  
  
  Overall the frequency of postoperative cerebral ME rose to 600% of preoperative values. Primarily gaseous ME occurred preoperatively and postoperatively [19 (6; 63) vs 116 (24; 373), P  < 0.001], while the number of solid ME was negligibly small [1 (0; 2) vs 2 (0; 6), P  < 0.001]. CBFV and cerebral tissue oxygen index remained unaltered bilaterally before and after surgery.
  
  
  
  Our findings indicate that cerebral ME considerably increase after major orthopaedic surgery under general anaesthesia. The predominant accumulation of gaseous ME and their preoperative occurrence, suggest that the general anaesthesia and individual patient factors may contribute to the embolic load in addition to orthopaedic surgery.
  
  
  
  . NCT02340416.
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Kietaibl
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Engel
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: I
authors.initials: I
authors.lastname: Horvat Menih
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Huepfl
authors.affiliation: Department of Anaesthesiology and Pain Therapy, Bern University Hospital, University of Bern, Freiburgstrasse, CH-3010, Bern, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Erdoes
authors.affiliation: Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Kubista
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Ullrich
authors.affiliation: Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Windhager
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Markstaller
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, A-1090, Austria.
authors.forename: K U
authors.initials: KU
authors.lastname: Klein
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D018570:Risk Assessment; D013131:Spine / Q000601:surgery; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
keywords: Doppler; intracranial embolism; orthopaedics; transcranial; ultrasonography