title: Identification of a statistical method as a quality tool: patient's length of stay in the operating room.
abstract: OBJECTIVE
  To identify a statistical method that may express the patient length of stay in the operating room and build a 'matrix of relationship' for optimizing this time, the real and exact time of the operation.
  
  
  METHODS
  The analysis of survival and the Kaplan-Meier estimator allowed to calculate the survival curves for different times and the 'matrix of relationship' with 10 hypothesis to help in choosing the new operation. The study consisted of a simple random sample of 71 patients, from elective operations for adults in Cardiac Surgery/Clinics Hospital/Unicamp, with confidence level of 95% in 2008.
  
  
  RESULTS
  On average, the times of the operations over at a range of 140 minutes to 200 minutes and excess from 5 minutes to 90 minutes. In general, on average, one operation was daily performed within 520 minutes, for a time of 720 minutes.
  
  
  CONCLUSIONS
  1) With the maximum available time of 720 minutes is not possible to perform surgery, unless using the 'matrix of relationship', whereas the maximum time available varies between 660 minutes and 690 minutes, considering the range of cleaning of the room. 2) The time of the patient in the operating room is a time that includes the time of learning by the student in an university hospital school. 3) When optimizing the time, most patients will benefit, causing a decrease from the waiting list for new opeartions. 4) The 'matrix of relationship' allows to view and express opinion on a better decision making in addition to decide upon several assumptions.
authors.affiliation: Statistical Department at HC/UNICAMP, Campinas, SP, Brazi. guiomar@hc.unicamp.br
authors.forename: Guiomar Terezinha Carvalho
authors.initials: GT
authors.lastname: Aranha
authors.forename: Reinaldo Wilson
authors.initials: RW
authors.lastname: Vieira
authors.forename: Pedro Paulo Martins de
authors.initials: PP
authors.lastname: Oliveira
authors.forename: Orlando
authors.initials: O
authors.lastname: Petrucci
authors.forename: Benedito Galvão
authors.initials: BG
authors.lastname: Benze
authors.forename: Lindemberg da Mota
authors.initials: Lda M
authors.lastname: Silveira Filho
authors.forename: Karlos Alexandre de Souza
authors.initials: KA
authors.lastname: Vilarinho
authors.forename: Lívia Paschoalino de
authors.initials: LP
authors.lastname: Campos
mesh_terms: D001014:Aortic Aneurysm / Q000601:surgery; D006348:Cardiac Surgical Procedures / Q000706:statistics & numerical data*; D006330:Heart Defects, Congenital / Q000601:surgery; D006349:Heart Valve Diseases / Q000601:surgery; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D017202:Myocardial Ischemia / Q000601:surgery; D009873:Operating Rooms / Q000706:statistics & numerical data*; D011785:Quality Assurance, Health Care; D016019:Survival Analysis; D013997:Time Factors