title: Variability in systemic arterial pressure during closed- and open-bridge extracorporeal life support: an in vitro evaluation.
abstract: OBJECTIVE
  To compare fluctuations in systemic arterial pressure (SAP) resulting from changes in systemic vascular resistance (SVR) during closed- and open-bridge extracorporeal life support (ECLS).
  
  
  METHODS
  In vitro laboratory study.
  
  
  METHODS
  Physiology laboratory of a tertiary care pediatric hospital.
  
  
  METHODS
  A standard neonatal ECLS circuit with simulated SAP was established using normal saline as circulating fluid. Our reference setting included an extracorporeal flow rate of 300 mL/min, a simulated SAP of 60 mm Hg, and a postoxygenator pressure of 150 mm Hg. The simulated SVR was modified by changing the degree of occlusion of the arterial catheter distal to the bridge. For this purpose, we used a graduated clamping device. Subsequently, the pressure changes were measured at four ports in the circuit. They were located as follows: a) on the venous tubing of the circuit between the bridge and the reservoir; b) on the arterial tubing of the circuit between the heat exchanger and the bridge; c) between the first and the second resistance clamps on the arterial tubing of the circuit for monitoring the simulated systemic arterial pressure; and d) at the reservoir. The experiment was repeated with various extracorporeal flow rates to the reservoir (100-300 mL/min) and through the bridge (100-300 mL/min using a custom-made clamp). Variations in the simulated SAP created by varying degrees of occlusion and flow rates were compared with repeated measures analysis of variance followed by the Tukey-Kramer test.
  
  
  RESULTS
  The open-bridge ECLS significantly reduced the variations in the simulated SAP by 15% to 45% (p < .001) compared with the closed-bridge. During closed-bridge ECLS, flashing of the bridge resulted in a decrease in the SAP and transient reversal of flows through the arterial and venous cannulae.
  
  
  CONCLUSIONS
  Open-bridge ECLS decreases the fluctuations in the SAP that occur because of changes in the SVR. Open-bridge ECLS prevents transient iatrogenic changes in blood flow and blood pressure, caused by flashing of the bridge. Other potential advantages and disadvantages of the open-bridge ECLS are discussed. The application of prolonged open-bridge ECLS to the patients needs to be evaluated in animal models.
authors.affiliation: Division of Critical Care Medicine, Miami Children's Hospital, FL, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Totapally
authors.forename: J B
authors.initials: JB
authors.lastname: Sussmane
authors.forename: K
authors.initials: K
authors.lastname: Hultquist
authors.forename: D
authors.initials: D
authors.lastname: Sapp
authors.forename: N
authors.initials: N
authors.lastname: Andreoulakis
authors.forename: J
authors.initials: J
authors.lastname: Wolfsdorf
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D015199:Extracorporeal Membrane Oxygenation / Q000379:methods*; D008020:Life Support Care; D014655:Vascular Resistance