title: Preoperative respiratory muscle dysfunction is a predictor of prolonged invasive mechanical ventilation in cardiorespiratory complications after heart valve surgery.
abstract: OBJECTIVE
  To verify whether preoperative respiratory muscle strength and ventilometric parameters, among other clinically relevant factors, are associated with the need for prolonged invasive mechanical ventilation (PIMV) due to cardiorespiratory complications following heart valve surgery.
  
  
  METHODS
  Demographics, preoperative ventilometric and manometric data, and the hospital course of 171 patients, who had undergone heart valve surgery at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, were prospectively collected and subjected to univariate analysis for identifying the risk factors for PIMV.
  
  
  RESULTS
  The hospital mortality was 7%. About 6% of the patients, who had undergone heart valve surgery required PIMV because of postoperative cardiorespiratory dysfunction. Their hospital mortality was 60% (vs 4%, p < 0.001). Univariate analysis revealed that preoperative respiratory muscle dysfunction, characterized by maximal inspiratory and expiratory pressure below 70% of the predicted values combined with respiratory rate above 15 rpm during ventilometry, was associated with postoperative PIMV (p = 0.030, odds ratio: 50, 95% confidence interval (CI): 1.2-18). Postoperative PIMV was also associated with: (1) body mass index (BMI)<18.5 (odds ratio: 7.2, 95% CI: 1.5-32), (2) body weight < 50 kg (odds ratio: 6.5, 95% CI: 1.6-25), (3) valve operation due to acute endocarditis (odds ratio: 5.5, 95% CI: 0.98-30), and (4) concomitant operation for mitral and tricuspid valve dysfunction (p = 0.047, odds ratio: 5.0, 95% CI: 1.1-22).
  
  
  CONCLUSIONS
  Our results have demonstrated that respiratory muscle dysfunction, among other clinical factors, is associated with the need for PIMV due to cardiovascular or pulmonary dysfunction after heart valve surgery.
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil. alfredo@fmrp.usp.br
authors.forename: Alfredo José
authors.initials: AJ
authors.lastname: Rodrigues
authors.forename: Viviany
authors.initials: V
authors.lastname: Mendes
authors.forename: Paulo Eduardo Gomes
authors.initials: PE
authors.lastname: Ferreira
authors.forename: Marcia Arruda Fajardo
authors.initials: MA
authors.lastname: Xavier
authors.forename: Viviane Santos
authors.initials: VS
authors.lastname: Augusto
authors.forename: Solange
authors.initials: S
authors.lastname: Bassetto
authors.forename: Paulo Roberto Barbosa
authors.initials: PR
authors.lastname: Evora
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000628:therapy; D004812:Epidemiologic Methods; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D011182:Postoperative Care / Q000379:methods; D011184:Postoperative Period; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D012120:Respiration Disorders / Q000209:etiology* / Q000628:therapy; D012121:Respiration, Artificial; D012132:Respiratory Muscles / Q000503:physiopathology*; D056152:Respiratory Rate / Q000502:physiology