title: Kinetics of arterial carbon dioxide during veno-venous extracorporeal membrane oxygenation support in an apnoeic porcine model.
abstract: BACKGROUND
  Extracorporeal membrane oxygenation (ECMO) is a technique widely used worldwide to improve gas exchange. Changes in ECMO settings affect both oxygen and carbon dioxide. The impact on oxygenation can be followed closely by continuous pulse oximeter. Conversely, carbon dioxide equilibrates much slower and is not usually monitored directly.
  
  
  METHODS
  We investigated the time to stabilization of arterial carbon dioxide partial pressure (PaCO2) following step changes in ECMO settings in 5 apnoeic porcine models under veno-venous ECMO support with polymethylpentene membranes. We collected sequential arterial blood gases at a pre-specified interval of 50 min using a sequence of standardized blood and sweep gas flow combinations.
  
  
  RESULTS
  Following the changes in ECMO parameters, the kinetics of carbon dioxide was dependent on sweep gas and ECMO blood flow. With a blood flow of 1500 mL/min, PaCO2 takes longer than 50 min to equilibrate following the changes in sweep gas flow. Furthermore, the sweep gas flow from 3.0 to 10.0 L/min did not significantly affect PaCO2. However, with a blood flow of 3500 mL/min, 50 min was enough for PaCO2 to reach the equilibrium and every increment of sweep gas flow (up to 10.0 L/min) resulted in additional reductions of PaCO2.
  
  
  CONCLUSIONS
  Fifty minutes was enough to reach the equilibrium of PaCO2 after ECMO initiation or after changes in blood and sweep gas flow with an ECMO blood flow of 3500 ml/min. Longer periods may be necessary with lower ECMO blood flows.
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. p.mendes@hc.fm.usp.br.|Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. p.mendes@hc.fm.usp.br.
authors.forename: Pedro Vitale
authors.initials: PV
authors.lastname: Mendes
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. marcelo10pk@gmail.com.|Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. marcelo10pk@gmail.com.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Park
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. alexandre.toledo@intensimed.com.|Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. alexandre.toledo@intensimed.com.
authors.forename: Alexandre Toledo
authors.initials: AT
authors.lastname: Maciel
authors.affiliation: Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. de_enf@hotmail.com.
authors.forename: Débora Prudêncio
authors.initials: DP
authors.lastname: E Silva
authors.affiliation: Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. nati_friedrich@hotmail.com.
authors.forename: Natalia
authors.initials: N
authors.lastname: Friedrich
authors.affiliation: Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. edzangelavs@yahoo.com.br.
authors.forename: Edzangela Vasconcelos Santos
authors.initials: EV
authors.lastname: Barbosa
authors.affiliation: Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. adrihirota@yahoo.com.br.
authors.forename: Adriana Sayuri
authors.initials: AS
authors.lastname: Hirota
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. gppschettino@uol.com.br.
authors.forename: Guilherme Pinto Paula
authors.initials: GP
authors.lastname: Schettino
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. lucianoazevedo@uol.com.br.|Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. lucianoazevedo@uol.com.br.
authors.forename: Luciano Cesar Pontes
authors.initials: LC
authors.lastname: Azevedo
authors.affiliation: Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil. eduardoleitecosta@gmail.com.|Intensive Care Unit, Hospital das Clinicas, University of São Paulo School of Medicine, Sixth floor-room 6040, Rua Dr. Eneas Carvalho de Aguiar, 255, São Paulo, 05623-010, Brazil. eduardoleitecosta@gmail.com.
authors.forename: Eduardo Leite Vieira
authors.initials: EL
authors.lastname: Costa
keywords: Acute respiratory distress syndrome; Mechanical ventilation; Swine and extracorporeal membrane oxygenation