title: New equipment to prevent carbon dioxide rebreathing during eye surgery under retrobulbar anaesthesia.
abstract: BACKGROUND
  Carbon dioxide concentration under ophthalmic drapes increases during eye surgery under local anaesthesia. A new prototype has been designed which combines continuous suction of carbon dioxide enriched air and continuous oxygen insufflation under ophthalmic drapes to prevent carbon dioxide accumulation in spontaneously breathing patients undergoing cataract surgery.
  
  
  METHODS
  In a prospective randomised single blind study the effectiveness of this new prototype was examined in 50 unpremedicated elderly patients. In 25 patients suction was applied under ophthalmic drapes, whereas in the other 25 patients no suction was used. In all cases oxygen was insufflated under the drapes at a constant flow of 2 l/min. Carbon dioxide concentration in the ambient air surrounding the patient's head under ophthalmic drapes, transcutaneous partial pressure of carbon dioxide, respiratory rate, and oxygen saturation were measured.
  
  
  RESULTS
  Carbon dioxide concentration under the drapes, transcutaneous partial pressure of carbon dioxide, and respiratory rate remained unchanged in the suction group, whereas in the non-suction group these values increased significantly. Oxygen saturation rose significantly in both groups without differences between the groups.
  
  
  CONCLUSIONS
  Application of this new prototype for continuous aspiration of carbon dioxide enriched air prevents carbon dioxide rebreathing and subsequent hypercapnia associated with an elevated respiratory rate. This new equipment may therefore be useful in patients undergoing ophthalmic surgery under retrobulbar anaesthesia.
authors.affiliation: Department of Anaesthesia and General Intensive Care Medicine, Division of Anaesthesia, The Leopold Franzens University of Innsbruck, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Schlager
authors.forename: H
authors.initials: H
authors.lastname: Staud
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000772:Anesthesia, Local; D002245:Carbon Dioxide / Q000032:analysis*; D002387:Cataract Extraction; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000517:prevention & control*; D007430:Intraoperative Care / Q000295:instrumentation*; D007431:Intraoperative Complications / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D012119:Respiration; D016037:Single-Blind Method; D013396:Suction / Q000295:instrumentation
chemical_list: D002245:Carbon Dioxide