title: Predicted preoperative maximal static respiratory pressures in adult cardiac surgeries: evaluation of two formulas.
abstract: OBJECTIVE
  Cardiac surgery (CC) determines systemic and pulmonary changes that require special care. Awareness of the importance of respiratory muscle dysfunction in the development of respiratory failure motivated several studies conducted in healthy subjects to assess muscle strength. These studies were carried out by evaluating the maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values. This study examined the concordance among the values predicted by the equations proposed by Black & Hyatt and Neder, and the measured values in cardiac surgery (CS) patients.
  
  
  METHODS
  Data were collected from preoperative evaluation forms. The Lin coefficient and Bland-Altman plots were used for statistical concordance analysis. The multiple linear regression and analysis of variance (ANOVA) were used to produce new formulas.
  
  
  RESULTS
  There were weak correlations of 0.22 and 0.19 in the MIP analysis and of 0.10 and 0.32 in the MEP analysis, for the formulas of Black & Hyatt and Neder, respectively. The ANOVA for both MIP and MEP were significant (P <0.0001), and the following formulas were developed: MIP = 88.82 - (0.51 x age) + (19.86 x gender), and MEP = 91.36 - (0.30 x age) + (29.92 x gender).
  
  
  CONCLUSIONS
  The Black and Hyatt and Neder formulas predict highly discrepant values of MIP and MEP and should not be used to identify muscle weakness in CS patients.
authors.affiliation: Department of Surgery and Anatomy, Ribeirão Preto Faculty of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Ricardo Kenji
authors.initials: RK
authors.lastname: Nawa
authors.forename: Ada Clarice
authors.initials: AC
authors.lastname: Gastaldi
authors.forename: Elisângela Aparecida Soares
authors.initials: EA
authors.lastname: da Silva
authors.forename: Viviane Dos Santos
authors.initials: Vdos S
authors.lastname: Augusto
authors.forename: Alfredo José
authors.initials: AJ
authors.lastname: Rodrigues
authors.forename: Paulo Roberto Barbosa
authors.initials: PR
authors.lastname: Evora
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018908:Muscle Weakness / Q000503:physiopathology; D057234:Preoperative Period; D011312:Pressure; D012016:Reference Values; D012129:Respiratory Function Tests / Q000379:methods*; D012132:Respiratory Muscles / Q000502:physiology*; D012737:Sex Factors; D055815:Young Adult