title: Safety of pressure-volume curve measurement in acute lung injury and ARDS using a syringe technique.
abstract: OBJECTIVE
  To assess the safety of frequent pressure-volume (PV) curve measurement in patients with acute lung injury (ALI)/ARDS.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Academic medical-surgical critical care unit.
  
  
  METHODS
  Consecutive patients with ALI or ARDS.
  
  
  METHODS
  Static inspiratory PV curves of the respiratory system were determined twice on day 1, then once daily for up to 6 days using a syringe. At each time point, three separate measurements of the PV curve were made. A 100-mL graduated syringe was used to inflate patients' lungs with 50- to 100-mL increments up to an airway pressure of 45 cm H(2)O or a total volume of 2 L; each volume step was maintained for 2 to 3 s until a plateau airway pressure was recorded. Outcome measures were mean arterial BP, heart rate (HR), and oxyhemoglobin saturation (SpO(2)) prior to and immediately after PV curve measurement. There were a priori criteria for procedure discontinuation if poorly tolerated.
  
  
  RESULTS
  Eleven patients were enrolled with a total of 134 PV curves generated. SpO(2) was 93 +/- 4% (mean +/- SD) before and fell to a nadir of 89 +/- 5% during PV curve measurement (p < 0.001), but increased to 97 +/- 4% immediately afterwards (p < 0.001, before vs after). HR rose from 106 +/- 22 to 108 +/- 22 beats/min immediately after the maneuver (p < 0.001). Mean arterial BP was 93 +/- 15 mm Hg before and 100 +/- 17 mm Hg immediately afterwards (p < 0.001). During PV curve measurement, systolic BP in one patient fell to 64 mm Hg from 113 mm Hg; in another patient, SpO(2) dropped to 79% from 89%. Both changes were transient. The study was discontinued in one patient because of inability to tolerate zero positive end-expiratory pressure; in another patient, the study was discontinued because of the development of subcutaneous emphysema.
  
  
  CONCLUSIONS
  PV curve measurement by syringe technique is well tolerated in most patients. Nonetheless, the maneuver may cause significant changes in oxygenation and/or hemodynamics, necessitating close monitoring.
authors: InterDepartmental Critical Care Medicine Division (Drs. Lee and Stewart) and the Department of Medicine, Division of Respirology (Drs. Mehta and Lapinsky), University of Toronto.
authors: Warren L
authors: WL
authors: Lee
authors: Thomas E
authors: TE
authors: Stewart
authors: Rod
authors: R
authors: MacDonald
authors: Stephen
authors: S
authors: Lapinsky
authors: David
authors: D
authors: Banayan
authors: David
authors: D
authors: Hallett
authors: Sangeeta
authors: S
authors: Mehta
mesh_terms: D000328:Adult; D000368:Aged; D000399:Air Pressure; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006801:Humans; D008176:Lung Volume Measurements / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy; D013594:Syringes
chemical_list: D010100:Oxygen