title: Decreased lung compliance increases preload dynamic tests in a pediatric acute lung injury model.
abstract: BACKGROUND
  Preload dynamic tests, pulse pressure variation (PPV) and stroke volume variation (SVV) have emerged as powerful tools to predict response to fluid administration. The influence of factors other than preload in dynamic preload test is currently poorly understood in pediatrics. The aim of our study was to assess the effect of tidal volume (VT) on PPV and SVV in the context of normal and reduced lung compliance in a piglet model.
  
  
  METHODS
  Twenty large-white piglets (5.2±0.4kg) were anesthetized, paralyzed and monitored with pulse contour analysis. PPV and SVV were recorded during mechanical ventilation with a VT of 6 and 12mL/kg (low and high VT, respectively), both before and after tracheal instillation of polysorbate 20.
  
  
  RESULTS
  Before acute lung injury (ALI) induction, modifications of VT did not significantly change PPV and SVV readings. After ALI, PPV and SVV were significantly greater during ventilation with a high VT compared to a low VT (PPV increased from 8.9±1.2 to 12.4±1.1%, and SVV from 8.5±1.0 to 12.7±1.2%, both P<0.01).
  
  
  CONCLUSIONS
  This study found that a high VT and reduced lung compliance due to ALI increase preload dynamic tests, with a greater influence of the latter. In subjects with ALI, lung compliance should be considered when interpreting the preload dynamic tests.
authors.affiliation: Centro de Medicina Regenerativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.
authors.forename: Benjamín
authors.initials: B
authors.lastname: Erranz
authors.affiliation: Department of Paediatric, Division of Pediatric Critical Care, University of Alabama at Birmingham, USA.
authors.forename: Franco
authors.initials: F
authors.lastname: Díaz
authors.affiliation: Unidad de Paciente Crítico Pediátrico, Hospital Clínico Metropolitano La Florida, Santiago, Chile.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Donoso
authors.affiliation: Unidad de Cuidados Intensivos Pediátrica, Clínica Alemana de Santiago, Chile.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Salomón
authors.affiliation: Unidad de Cuidados Intensivos Pediátrica, Clínica Alemana de Santiago, Chile.
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Carvajal
authors.affiliation: Unidad de Cuidados Intensivos Pediátrica, Clínica Alemana de Santiago, Chile.
authors.forename: María Fernanda
authors.initials: MF
authors.lastname: Torres
authors.affiliation: Unidad de Paciente Crítico Pediátrico, Hospital El Carmen de Maipú, Santiago, Chile; Centro de Investigación de Medicina Veterinaria, Escuela de Medicina Veterinaria, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello, Santiago, Chile. Electronic address: pcrucesr@gmail.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Cruces
mesh_terms: D055371:Acute Lung Injury / Q000503:physiopathology*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D005440:Fluid Therapy / Q000379:methods*; D008170:Lung Compliance / Q000502:physiology*; D012121:Respiration, Artificial / Q000379:methods; D013318:Stroke Volume / Q000502:physiology; D013552:Swine; D013990:Tidal Volume / Q000502:physiology*
keywords: Acute lung injury; Hemodinamia; Hemodynamics; Lesión Pulmonar Aguda; Mechanical ventilation; Pediatric; Pediatría; Precarga; Preload; Ventilación Mecánica