title: Echocardiographic monitoring during induction of general anesthesia with a miniaturized esophageal probe.
abstract: Standard transesophageal echocardiography (TEE) does not allow cardiac monitoring during the induction of anesthesia because standard probes would limit the oropharyngeal space and impair mask ventilation and tracheal intubation. We hypothesized that a prototype, miniaturized TEE probe could be safely introduced transnasally in awake patients and that mask ventilation and orotracheal intubation could be performed while continuously monitoring left ventricular (LV) function during the induction of anesthesia. Forty-five patients were studied prospectively. The transnasal TEE probe was introduced through one of the nares and advanced until a transverse plane image of the LV at the level of the papillary muscles was seen. Anesthesia was induced, and the patients were ventilated with a mask that had previously been threaded over the TEE probe via a central perforation. Probe insertion was successful in 12 patients under local anesthesia alone and in an additional 31 patients with a combination of local anesthesia and mild sedation. In two cases, probe placement was unsuccessful. Overall, hemodynamic variables did not change significantly during insertion. No case of significant mucosal bleeding was seen. In one patient, regurgitation of gastric contents occurred without affecting the perioperative outcome. The two-dimensional echocardiogram image quality of the LV during the induction of anesthesia was good or acceptable in 95% of patients. We conclude that transnasal TEE can effectively be used for cardiac monitoring during the induction of general anesthesia.
  
  
  CONCLUSIONS
  This study demonstrates that it is feasible and generally safe to introduce a miniaturized transesophageal echocardiography probe transnasally in awake cardiac risk patients to monitor cardiac performance during the induction of general anesthesia.
authors.affiliation: Department of Anesthesiology, University of Würzburg Medical Center, Germany. peter.zimmermann@lycos.com
authors.forename: Peter
authors.initials: P
authors.lastname: Zimmermann
authors.forename: Clemens
authors.initials: C
authors.lastname: Greim
authors.forename: Herbert
authors.initials: H
authors.lastname: Trautner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sagmeister
authors.forename: Katharina
authors.initials: K
authors.lastname: Kraemer
authors.forename: Norbert
authors.initials: N
authors.lastname: Roewer
mesh_terms: D000368:Aged; D000768:Anesthesia, General; D017548:Echocardiography, Transesophageal / Q000009:adverse effects / Q000295:instrumentation*; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000009:adverse effects / Q000295:instrumentation*; D009200:Myocardial Contraction / Q000502:physiology; D036103:Nanotechnology / Q000295:instrumentation*; D009296:Nasal Cavity / Q000502:physiology; D011229:Preanesthetic Medication; D011446:Prospective Studies; D012121:Respiration, Artificial; D016277:Ventricular Function, Left / Q000502:physiology