title: Release of particulate matter from extracorporeal tubing: ineffectiveness of standard arterial line filters during bypass.
abstract: Microemboli resulting from extracorporeal circulation have been considered to be a cause of organ dysfunction after cardiopulmonary bypass. A scanning electron microscopic study was carried out to quantitate the number of nonbiological particles which escape capture by the arterial line filter in a standard extracorporeal circulation circuit. Five different lots of polyvinylchloride (PVC) tubing from the same manufacturer were used in closed circuit extracorporeal pump set-ups consisting of a typical length of PVC tubing, a cardiotomy reservoir, and an arterial line filter (Pall 40 microns (mu)). A liter of Plasmalyte was circulated through this set-up for 15 minutes at 2 liters/minute with the pump head set at almost total occlusion. The circulated Plasmalyte from each pump line was then collected and passed through a 0.22 mu Millipore filter. Numerous particles ranging from 5-40 mu in diameter were observed on the surface of the filters. A mean of 51.2 particles/mm2 of filter was found after the first recirculation period. By extrapolation the mean total number of particles contained in the Plasmalyte was calculated to be 70,943. A second similar 15 minute rinse on the same pump set-ups revealed the release of a mean of 51.0 particles/mm2, or a mean total number of 70,665 particles. Analysis of variance showed no significant difference in the number of particles produced by the first compared with the second recirculation period but there were significant differences (P less than .05) between the numbers of particles produced by the different lots of tubing. This study demonstrates that commonly employed tubing packs and standard roller pump designs for extracorporeal circulation are associated with continuous release of particulate matter (5-40 mu) which is not removed by the arterial line filters most often employed. These particles seem to be released at a constant rate which makes an initial pre-bypass filtration run ineffective. Such particles can only be removed by continuous use of lower porosity filters in the pump circuit. The clinical significance of these large numbers of small particles is unknown, but they may contribute to the multi-organ failure often seen in prolonged (greater than 2 hour) periods of cardiopulmonary bypass.
mesh_terms: D004868:Equipment Failure; D005112:Extracorporeal Circulation / Q000009:adverse effects*; D008851:Micropore Filters / Q000592:standards*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D011143:Polyvinyl Chloride / Q000009:adverse effects
chemical_list: D011143:Polyvinyl Chloride