title: Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung.
abstract: BACKGROUND
  Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes.
  
  
  METHODS
  Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows.
  
  
  RESULTS
  Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow) and a negative association of pressure drop with temperature (-4.828 mmHg/(°Celsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined.
  
  
  CONCLUSIONS
  During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0-5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature.
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil marcelo.park@hc.fm.usp.br.
authors.forename: M
authors.initials: M
authors.lastname: Park
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: E L V
authors.initials: EL
authors.lastname: Costa
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: A T
authors.initials: AT
authors.lastname: Maciel
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: E V S
authors.initials: EV
authors.lastname: Barbosa
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: A S
authors.initials: AS
authors.lastname: Hirota
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: G de P
authors.initials: Gde P
authors.lastname: Schettino
authors.affiliation: Research and Education Institute, Sírio Libanês Hospital, São Paulo, Brazil Intensive Care Unit, Emergency Department, Hospital das Clínicas, São Paulo, Brazil.
authors.forename: L C P
authors.initials: LC
authors.lastname: Azevedo
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001831:Body Temperature; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D009102:Multiple Organ Failure / Q000503:physiopathology* / Q000601:surgery*; D013552:Swine
keywords: acute respiratory distress syndrome; extracorporeal membrane oxygenation and multiple-organ failure; mechanical ventilation; swine