title: Intra-operative blood loss and operating time in orthognathic surgery using induced hypotensive general anaesthesia: prospective study.
abstract: We investigated the average operating time and extent of intra-operative blood loss in orthognathic surgeries performed using induced hypotensive general anaesthesia, with the intention of devising a practical guideline for blood unit preparation for these procedures. We prospectively studied 32 Chinese patients undergoing surgery to correct dentofacial deformities at a public hospital in Hong Kong from 1 December 1997 to 1 December 1998. Most patients (72. 4%) needed double-jaw surgery. The mean estimated blood loss was approximately 617.6 mL. The blood loss during simple Le Fort I osteotomies was about half that of multiple segmentalised osteotomies. For mandibular ramus osteotomies, the mean blood loss and operating time for were approximately 280 mL and 2 hours, respectively; for anterior mandibular osteotomies, the corresponding values were 171.3 mL and 1 hour 13 minutes. The average drop in the haematocrit value was 15.4%, and the crossmatch to transfusion ratio was 29. A bivariate correlation test between the blood loss and operating time gave a strong correlation (P<0.01), as did blood loss with a drop in haematocrit value (P<0.01). Orthognathic surgeries are thus safe and predictable in terms of intra-operative blood loss and operating time, and a 'type, screen, and save' policy for blood unit preparation is more appropriate than a 'crossmatch' policy.
authors.affiliation: Department of Dentistry and Maxillofacial Surgery, United Christian Hospital, Kwun Tong, Hong Kong.
authors.forename: C N
authors.initials: CN
authors.lastname: Yu
authors.forename: T K
authors.initials: TK
authors.lastname: Chow
authors.forename: A S
authors.initials: AS
authors.lastname: Kwan
authors.forename: S L
authors.initials: SL
authors.lastname: Wong
authors.forename: S C
authors.initials: SC
authors.lastname: Fung
mesh_terms: D000293:Adolescent; D000328:Adult; D000768:Anesthesia, General / Q000379:methods*; D016063:Blood Loss, Surgical; D005260:Female; D006779:Hospitals, Public; D006801:Humans; D007023:Hypotension, Controlled; D007432:Intraoperative Period; D008297:Male; D010027:Osteotomy / Q000379:methods*; D019340:Osteotomy, Le Fort; D011446:Prospective Studies