title: Effect of thoracentesis on respiratory mechanics and gas exchange in the patient receiving mechanical ventilation.
abstract: BACKGROUND
  This study reports the effect of thoracentesis on respiratory mechanics and gas exchange in patients receiving mechanical ventilation.
  
  
  METHODS
  Prospective.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Eight patient receiving mechanical ventilation with unilateral (n = 7) or bilateral (n = 1) large pleural effusions.
  
  
  METHODS
  Therapeutic thoracentesis (n = 9).
  
  
  METHODS
  Resistances of the respiratory system measured with the constant inspiratory flow interrupter method measuring peak pressure and plateau pressure, effective static compliance of the respiratory system (Cst,rs), work performed by the ventilator (Wv), arterial blood gases, mixed exhaled Pco2, and pleural liquid pressure (Pliq).
  
  
  RESULTS
  Thoracentesis resulted in a significant decrease in Wv and Pliq. Thoracentesis had no significant effect on dynamic compliance of the respiratory system; Cst,rs; effective interrupter resistance of the respiratory system, or its subcomponents, ohmic resistance of the respiratory system and additional (non-ohmic) resistance of the respiratory system; or intrinsic positive end-expiratory pressure (PEEPi). Indices of gas exchange were not significantly changed by thoracentesis.
  
  
  CONCLUSIONS
  Thoracentesis in patients receiving mechanical ventilatory support results in significant reductions of Pliq and Wv. These changes were not accompanied by significant changes of resistance or compliance or by significant changes in gas exchange immediately after thoracentesis. The reduction of Wv after thoracentesis in patients receiving mechanical ventilation is not accompanied by predictable changes in inspiratory resistance and static compliance measured with routine clinical methods. The benefit of thoracentesis may be most pronounced in patients with high levels of PEEPi.
authors.affiliation: Division of Pulmonary and Critical Care Medicine 7D, Beth Israel Medical Center, New York, NY 10003, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Doelken
authors.forename: Ricardo
authors.initials: R
authors.lastname: Abreu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Sahn
authors.forename: Paul H
authors.initials: PH
authors.lastname: Mayo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000502:physiology; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D019152:Paracentesis; D035422:Pleural Cavity / Q000503:physiopathology; D010996:Pleural Effusion / Q000628:therapy*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology*