title: Systemic gaseous microemboli during left atrial catheterization: a common occurrence?
abstract: OBJECTIVE
  Gaseous microemboli during cardiac surgery have been implicated as a potential cause of postoperative neurologic injury. Any monitoring technique that exposes the systemic circulation to atmospheric pressure could introduce gaseous microemboli, causing cerebral microembolization. The incidence of carotid artery gaseous microemboli was studied during left atrial catheter insertion.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Tertiary care university hospital.
  
  
  METHODS
  Twelve patients undergoing elective cardiac surgery.
  
  
  METHODS
  Perioperatively, a 5-MHz continuous wave Doppler probe was positioned over the left carotid artery to maximally record blood flow signals. The criteria used for detecting a gaseous microembolus were a sudden increase in the amplitude of the visual signal by 30% and a characteristic audible sound.
  
  
  RESULTS
  Numbers of microemboli at three timepoints (before and during left atrial catheter insertion and during catheter flushing) were assessed using the Friedman test. No emboli were detected before left atrial catheter insertion. When compared with the preinsertion time period, statistically (p < 0.05) significant numbers of gaseous microemboli were found in six patients during catheter insertion (3 +/- 1 microemboli; range 1 to 7 microemboli) and in five patients during catheter flushing (5 +/- 2 microemboli; range 1 to 12 microemboli). There was a tendency for patients with lower filling pressures to entrain more microemboli during insertion (r = 0.44; p = 0.149). No patient showed evidence of gross neurologic dysfunction postoperatively, although sensitive neurologic testing was not performed.
  
  
  CONCLUSIONS
  Left atrial catheter insertion and flushing can cause systemic gaseous microemboli in more than 50% of patients. Although the number of microemboli introduced is relatively small, extreme care should be used during left atrial catheter insertion.
authors.affiliation: Department of Anesthesiology, University of Texas Medical Branch, Galveston 77555-0591, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Feerick
authors.forename: J A
authors.initials: JA
authors.lastname: Church
authors.forename: J
authors.initials: J
authors.lastname: Zwischenberger
authors.forename: V
authors.initials: V
authors.lastname: Conti
authors.forename: W E
authors.initials: WE
authors.lastname: Johnston
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016279:Atrial Function, Left; D001794:Blood Pressure; D006328:Cardiac Catheterization / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D006348:Cardiac Surgical Procedures; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging; D017558:Elective Surgical Procedures; D004618:Embolism, Air / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D006325:Heart Atria; D006801:Humans; D015994:Incidence; D002542:Intracranial Embolism and Thrombosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications; D011446:Prospective Studies; D012039:Regional Blood Flow; D018608:Ultrasonography, Doppler