Ex vivo testing of the Quart® arterial line filter

Abstract

Arterial line filters are now routinely used in cardiac surgery in order to decrease the microemboli load to the patient. The Quart filter (Jostra, Hirrlingen, Germany) with a new planar construction design, an easy de-airing system and an integrated bypass, was tested for air filtration capacity and resistance to blood path in a standardized setting with surviving animals. Three calves (mean body weight: 71+/-3.4 kg) were connected to a standard cardiopulmonary bypass (CPB) circuit by jugular venous and carotid arterial cannulation with a mean flow rate of 3.5 l/min. The arterial line filter was challenged with upstream injections of boluses of air of 5, 10 and 15 ml, respectively. A Doppler ultrasound was positioned downstream on the arterial line to measure bubble count and size. The pressure drop through the filter was monitored at flow rates of between 1 and 6 l/min. At the end of the procedure the animals were weaned from the CPB and, thereafter, from the ventilator. After 7 days, the animals were sacrificed electively. This study shows that important quantities of air can be injected into the arterial line upstream of the filter with small volumes of small sized bubbles recorded downstream. With the 5 ml air bolus injection, mean values of 0.3+/-0.6 bubbles of 30 and 40 microm were detected, whereas with the 20 ml bolus, 32.6+/-8.7 bubbles of 10 microm, 3.7+/-1.1 bubbles of 30 microm, 3.3+/-0.6 bubbles of 40 microm and 0.7+/-1.1 bubbles of 50 microm were recorded. The blood path resistance at different blood flow rates was well within the acceptable range with a pressure drop of 20+/-0 and 26.6+/-5.7 mmHg at flow rates of 4 and 5 l/min, respectively. With its planar concept, the Quart filter offers good air filtering capacity both in terms of bubble count and size after injection of large boluses of air, without any increase of resistance to the blood path. Moreover, it offers a venting function and an integrated bypass system.

Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

“…during cannulation of the right atrium, air often remains in the venous cannula when the cannula is connected to the venous return line of the cPB circuit. Air is not completely eliminated by the arterial line filter (15,16) and so the presence of air in the venous cannula increases the risk of cerebral air embolization during initiation of cPB. differences in individual techniques of de-airing the venous cannula and its connections have a significant impact on both the volume of air retained in the venous cannula and cerebral embolization during initiation of cPB (13).…”

“…therefore, most heart centers conventionally utilize arterial filters in cPB circuits. numerous studies have shown that the arterial line filter is not one hundred percent effective in blocking microemboli from returning to the patient via the arterial line (15,16). the method by which air traverses the arterial filter is not entirely clear but perhaps involves distortion of the bubbles into a "sausage" shape to fit through the pores or coalescence of fragmented bubbles distal to the filter.…”

Bubbles and bypass: an update

“…4) Arterial filter design has evolved from axial flow geometry to tangential flow entry with reduced blood velocities so as to take advantage of venting of GME before their contact with the filter media. 37 The optimum pore size has yet to be resolved. 5) Important gains in our understanding of the quantities of GME inherent in CPB and then correlating GME with patient neurologic dysfunction have been made, 38 but until newer detection methods to discriminate between particulate and GME are developed, the issue remains unresolved.…”

In vitro Air Removal Characteristics of Two Neonatal Cardiopulmonary Bypass Systems: Filtration May Lead to Fractionation of Bubbles

“…Cannulation, drug administration, blood sampling and some components of the CPB circuit are potential sources of GME during on-pump cardiac surgery (1–3). Introduction of GME into the arterial line of a CPB circuit may lead to cognitive decline and adverse outcomes in the patient (4, 5) and may also play a role in neurological dysfunction in neonatal and pediatric patients (6). In addition to GME, gross air may be introduced in the CPB circuit.…”