Ex vivo testing of the Quart (R) arterial line filter

Arterial line filters are now routinely used in cardiac surgery in order to decrease the microemboli load to the patient. The Quart(R) filter (Jostra, Hirrlingen, Germany) with a new planar construction design, an easy deairi ng system and an integrated bypass, was tested for air filtration capacity and resistance to blood path in a standardized setting with surviving anima ls. Three calves (mean body weight: 71 +/- 3.4 kg) were connected to a standard cardiopulmonary bypass (CPB) circuit by jugular venous and carotid arteria l 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 m i. respectively. A Doppler ultrasound was positioned downstream on the arte rial line to measure bubble count and size. The pressure drop through the f ilter was monitored at flow rates of between 1 and 6 l/min. At the end of t he 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 bubb les recorded downstream. With the 5 mi air bolus injection, mean values of 0.3 +/- 0.6 bubbles of 30 and 40 mu m were detected, whereas with the 20 mi bolus, 32.6 +/- 8.7 bubbles of 10 mu m. 3.7 +/- 1.1 bubbles of 30 pm, 3.3 +/- 0.6 bubbles of 40 mu m and 0.7 +/- 1.1 bubbles of 50 mu m were recorded . The blood path resistance at different blood flow rates was well within t he 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 capacit y both in terms of bubble count and size after injection of large boluses o f air, without any increase of resistance to the blood path. Moreover, it o ffers a venting function and an integrated bypass system.