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Particulate matter in bubble oxygenators
Particulate matter in bubble oxygenators The degree of contamination was evaluated in seven blood oxygenators in common use. The Bentley Q 100 unit was found to have the highest degree of particulate contamination and the Travenol 6LF the lowest. Evidence is presented in favor of adopting a micropore filtration and washing technique of the bubble oxygenator immediately before open-heart surgery. Vast amounts of particulate matter were removed from the seven types of blood oxygenators studied. The incidence of postoperative neurologic deficits decreased after the incorporation of this technique into the preparation of the heart-lung machine.
Charles C. Reed, B.S.,* Alex Romagnoli, M.D.,** Diane E. Taylor, B.S.,* and Diane K. Clark, B.S., * Houston, Texas
The presence of microemboli and the serious complications which they cause during and after cardiopulmonary bypass were recognized early. 1 Denaturation of plasma proteins," fat globulinemia," and air embolism- all produce serious organ dysfunction. 5 Garvan and Gunner" demonstrated in autopsy studies the presence of numerous pulmonary and cerebral granulomas following massive fluid and blood transfusions. These granulomas contained starch particles, crystals, or cellulose fibers. Osborn and assoelates" and later Goldiner" reported good results after using microfilters to trap damaged blood components. Connell and associates'' found that Dacron wool filters were excellent in blocking platelet and leukocyte aggregates. Several other studies have focused attention on the prevention and detection of emboli. Spencer'? reported the ultrasonic determination of microembolism in man. Kessler and Pattersonv- 12 systematically studied several oxygenators to From the Texas Heart Institute and the Texas Medical Center, Houston, Texas 77025. Received for publication May 22, 1974. 'Perfusion Technology Section, The Texas Heart Institute, P. O. Box 20345, Houston, Texas 77025. ••Associate Professor, Department of Anesthesiology, Baylor College of Medicine, Texas Medical Center, Houston, Texas 77025.
determine which were more likely to release air emboli during use. They rated several bubble oxygenators by utilizing an ultrasound device to record the concentration of particles in the arterial line during cardiopulmonary bypass in animals. Lately, Gerecke and colleagues> demonstrated a vast amount of foreign material in fluids used to prime bubble oxygenators prior to cardiopulmonary bypass; they used a 0.22 p. filter to trap these particles. Observation of particulate matter floating in several oxygenators after they were primed caused us to undertake a systematic study of the intravenous solutions and bubble oxygenators used in our center. Methods
Seventy bubble oxygenators were studied, ten of each type (Table I). The Harvey H200, the Harvey H200B, the Bentley Q 100, the Rygg, and the Travenol 6LF models are adult-sized oxygenators, whereas the Travenol 2LF is used for children up to 18 kilograms in weight. The Galen Optiflo oxygenator is used for both adults and children. All oxygenators were primed with 2 L. of 5 per cent dextrose in lactated Ringer's solution. All visible air bubbles were removed by gentle percussion. A Millipore fil-
971
The Journal of
972
Reed et al.
Thoracic and Cardiovascular Surgery
Table I. Count of foreign body particles in various bubble oxygenators (ten of each model) ',1, .•
"
Oxygenator
Mean
Bentley Q 100 Harvey H200 Harvey H200B Galen Optiflo Rygg Travenol 6 LF Travenol 2 LF
130,046 39,598 7,912 5,719 23,730 1,429 845
Range
10,530 20,702 927 987 1,974 239 299
to 480,100 to 66,773 to 25,458 to 30,125 to 115,893 4,248 to 2,812 to
Table II. Count of foreign body particles per liter of I. V. in solution (N = 10)
IMean I Range Fig. 1. Top, Millipore filter and membrane assembled. Bottom, The disengaged view shows (A) inlet, (B) inlet end plate, (C) 0 ring, (D) disposable filter membrane, and (E) outlet.
ter membrane (MFM), 5 p. size (Fig. 1), was placed between the arterial and the venous lines (Fig. 2). This size filter was chosen because such a size was believed adequate to trap all particles large enough to cause arteriolar or capillary obstruction, yet it would still allow a high flow rate (3 L. per minute). The priming solution was then circulated at 2 L. per minute for 5 minutes with an oxygen flow of 3 to 4 L. per minute. This allowed the priming solution to pass through the Millipore filter at least eight times. The excess prime was discarded. The filter was removed, opened, and placed under a microscope. Particles were counted at low power in five random fields in each of the four quadrants. This formula was used to calculate particulate matter count: x
y
=_.
w
z
where x is total count of foreign bodies, y is area of one microscope field (2.54 sq. mm.), z is area of MFM (1,520.5 sq. mm.), and w is mean foreign body count in 20 random fields. Since the preparation and priming of the
One liter of 5 per cent dextrose in RLS--without I.Y. administration set (Yialflex) One liter of 5 per cent dextrose in RLS--with LY. administration set (Yiaflex)
77
0 to 358
74
59 to 89
Legend: LV., Intravenous. RLS, Ringer's lactate solution.
oxygenator and the removal of the MFM was always accomplished under sterile conditions, the oxygenator was used for the operation as usual. The counts obtained in the various groups of oxygenators showed (Table I) that the Bentley Q 100 was the most highly contaminated: 130,046 (range 10,530 to 480,100). The Harvey H200 was second with a count of 39,598 (range 20,702 to 66,773); the Rygg was third, 23,730 (range 1,974 to 115,893); the Galen Optiflo was fourth, 5,719 (range 987 to 30,125); and the Travenol 6LF was fifth, 1,429 (range 239 to 4,248). The pediatric Travenol 2 LF had a count of 845 (range 299 to 2,812). This amount of contamination is approximately one half that of the adult oxygenator, but so is the size of the unit; therefore, the ratio of contamination is the same. Subsequent to our initial studies, the William Harvey Research Corporation produced an oxygenator (Model H200B) which provided an 81 per cent decrease in foreign body count, a considerable improvement. For comparison, 1 L. of 5 per cent dextrose with lactated Ringer's solution
Volume 68 Number 6 December, 1974
Particulate matter in bubble oxygenators
.
973
,.
Oxygenator
Fig. 2. Schematic drawing shows placement of the Millipore filter as utilized in the cardiopulmonary bypass circuit for rinsing and filtering the oxygenator.
Fig. 3. Photomicrograph of particulate matter. Cotton fiber and plastic chips are shown. (Original magnification x200.)
(Travenol) was passed through a given filter (Table II) . The particulate matter count was 77 (range zero to 358) when the solution passed through an intravenous administration set and 74 (range 59 to 89) when the solution was passed through the filter from the container. Although we did not attempt to establish accurately the nature of these particles, we found that approximately 86 per cent were fibers, 10 per cent plastic chips, and 4 per cent of undetermined nature (Fig. 3) (photomicrograph).
Discussion
When we consider that several thousand open-heart operations are performed daily in this country with the aid of oxygenators that have a relatively high foreign body content, it is not surprising that the incidence of neurologic deficits is significant. Until recently, postoperative neurologic complications have been attributed solely to air, fibrin, platelets , protein aggregates, fat, hypotension, and hypoperfusion. These findings as well as Gerecke's'" data show that
The Jaurnal of
974
Reed et al.
Thoracic and Cardiovascular Surgery
the size and composition of particulate matter flushed from bubble oxygenators can cause complete and permanent occlusion of finer blood vessels. This vascular occlusion could lead to infarction of the area supplied or to the establishment of collateral perfusion, depending upon where the particles become trapped. As Garvan and Gunner" demonstrated, granuloma formation is a distinct possibility. Before we began using this filtration technique, the incidence of neurologic deficits in our experience was 14.3 per cent in 692 open-heart procedures, including aorto-coronary bypass grafts, valve surgery, and surgery of congenital heart disease. This incidence has decreased with filtration to 10.7 per cent in 318 cases similarly distributed. Conclusion
Our simple filtration technique effectively removes vast amounts of foreign body material accumulated in bubble oxygenators and diminishes the incidence of neurologic deficits after cardiopulmonary bypass. Thus the technique helps to lessen the postoperative incidence of morbidity. We have incorporated the described filtration technique as a standard procedure in priming oxygenators for open-heart surgery. REFERENCES Helmsworth, J. A., Gall, E. A, Perrin, E. V., Braley, S. A, Flege, J. B., Jr., Kaplan, S., and Keirle, A. M.: Occurrence of Emboli During Perfusion With an Oxygenator Pump, Surgery 53: 177, 1963. 2 Lee, W. H., Jr., Krumhaar, D., Fonkalsrud, E. W., Schjeide, O. A., and Maloney, J. V., Jr.: Denaturation of Plasma Proteins as a Cause
of Morbidity and Death After Intracardiac Operations, Surgery 50: 29, 1961. 3 Wright, E. S., Sarkozy, E., Dobell, A R. C., and Murphy, D. R.: Fat Globulinemia in Extracorporeal Circulation, Surgery 53: 500, 1963. 4 Austen, W. G., and Howry, D. H.: Ultrasound to Detect Bubbles or Particulate Matter During Cardiopulmonary Bypass, J. Surg. Res. 5: 283, 1965. 5 Allardyce, D. 8., Yoshida, S. H., and Ashmore, P. G.: The Importance of Microembolism in the Pathogenesis of Organ Dysfunction Caused by Prolonged Use of the Pump Oxygenator, J. THORAC. CARDIOVASC. SURG. 52: 706, 1966. 6 Garvan, J. M., and Gunner, B: W.: The Harmful Effects of Particles in Intravenous Fluids, Med. J. Aust. 2: 1, 1964. 7 Osborn, J. J., Cohn, K., Hait, M., Russi, M., Salel, A., Harkins, G., and Gerbode, F.: Hemolysis During Perfusion, J. THORAC. CARDlOVASC. SURG. 43: 459, 1962. 8 Goldiner, P. L., Howland, W. S., and Ray, C., Jr.: Filter for Prevention of Microembolism During Massive Transfusions, J. Int. Anesth. Res. Soc. 51: 717,1972. 9 Connell, R. S., Page, U. S., Bartley, T. D., Bigelow, J. C., and Webb, M. C.: The Effect on Pulmonary Ultrastructure of Dacron-Wool Filtration During Cardiopulmonary Bypass, Ann. Thorac. Surg. 15: 217, 1973. 10 Spencer, M. P., Lawrence, G. H., Thomas, G. I., and Sauvage, L. R.: The Use of Ultrasonics in the Determination of Arterial Aeroembolism During Open-Heart Surgery, Ann. Thorac. Surg. 8: 489, 1969. II Kessler, J., and Patterson, R. H., Jr.: The Production of Microemboli by Various Blood Oxygenators, Ann. Thorac. Surg. 9: 221, 1970. I2 Patterson, R. H., Jr., and Kessler, J.: Microemboli During Cardiopulmonary Bypass Detected by Ultrasound, Surg, Gynecol. Obstet. 129: 505, 1969. I3 Gerecke, W. B., Crosthwait, R. W., and Angel, R. T.: Particulate Contamination in Cardiopulmonary Bypass: Importance of Delivery Systems and Intravenous Fluids. In press. 1973.
Charles C. Reed, B.S.,* Alex Romagnoli, M.D.,** Diane E. Taylor, B.S.,* and Diane K. Clark, B.S., * Houston, Texas
The presence of microemboli and the serious complications which they cause during and after cardiopulmonary bypass were recognized early. 1 Denaturation of plasma proteins," fat globulinemia," and air embolism- all produce serious organ dysfunction. 5 Garvan and Gunner" demonstrated in autopsy studies the presence of numerous pulmonary and cerebral granulomas following massive fluid and blood transfusions. These granulomas contained starch particles, crystals, or cellulose fibers. Osborn and assoelates" and later Goldiner" reported good results after using microfilters to trap damaged blood components. Connell and associates'' found that Dacron wool filters were excellent in blocking platelet and leukocyte aggregates. Several other studies have focused attention on the prevention and detection of emboli. Spencer'? reported the ultrasonic determination of microembolism in man. Kessler and Pattersonv- 12 systematically studied several oxygenators to From the Texas Heart Institute and the Texas Medical Center, Houston, Texas 77025. Received for publication May 22, 1974. 'Perfusion Technology Section, The Texas Heart Institute, P. O. Box 20345, Houston, Texas 77025. ••Associate Professor, Department of Anesthesiology, Baylor College of Medicine, Texas Medical Center, Houston, Texas 77025.
determine which were more likely to release air emboli during use. They rated several bubble oxygenators by utilizing an ultrasound device to record the concentration of particles in the arterial line during cardiopulmonary bypass in animals. Lately, Gerecke and colleagues> demonstrated a vast amount of foreign material in fluids used to prime bubble oxygenators prior to cardiopulmonary bypass; they used a 0.22 p. filter to trap these particles. Observation of particulate matter floating in several oxygenators after they were primed caused us to undertake a systematic study of the intravenous solutions and bubble oxygenators used in our center. Methods
Seventy bubble oxygenators were studied, ten of each type (Table I). The Harvey H200, the Harvey H200B, the Bentley Q 100, the Rygg, and the Travenol 6LF models are adult-sized oxygenators, whereas the Travenol 2LF is used for children up to 18 kilograms in weight. The Galen Optiflo oxygenator is used for both adults and children. All oxygenators were primed with 2 L. of 5 per cent dextrose in lactated Ringer's solution. All visible air bubbles were removed by gentle percussion. A Millipore fil-
971
The Journal of
972
Reed et al.
Thoracic and Cardiovascular Surgery
Table I. Count of foreign body particles in various bubble oxygenators (ten of each model) ',1, .•
"
Oxygenator
Mean
Bentley Q 100 Harvey H200 Harvey H200B Galen Optiflo Rygg Travenol 6 LF Travenol 2 LF
130,046 39,598 7,912 5,719 23,730 1,429 845
Range
10,530 20,702 927 987 1,974 239 299
to 480,100 to 66,773 to 25,458 to 30,125 to 115,893 4,248 to 2,812 to
Table II. Count of foreign body particles per liter of I. V. in solution (N = 10)
IMean I Range Fig. 1. Top, Millipore filter and membrane assembled. Bottom, The disengaged view shows (A) inlet, (B) inlet end plate, (C) 0 ring, (D) disposable filter membrane, and (E) outlet.
ter membrane (MFM), 5 p. size (Fig. 1), was placed between the arterial and the venous lines (Fig. 2). This size filter was chosen because such a size was believed adequate to trap all particles large enough to cause arteriolar or capillary obstruction, yet it would still allow a high flow rate (3 L. per minute). The priming solution was then circulated at 2 L. per minute for 5 minutes with an oxygen flow of 3 to 4 L. per minute. This allowed the priming solution to pass through the Millipore filter at least eight times. The excess prime was discarded. The filter was removed, opened, and placed under a microscope. Particles were counted at low power in five random fields in each of the four quadrants. This formula was used to calculate particulate matter count: x
y
=_.
w
z
where x is total count of foreign bodies, y is area of one microscope field (2.54 sq. mm.), z is area of MFM (1,520.5 sq. mm.), and w is mean foreign body count in 20 random fields. Since the preparation and priming of the
One liter of 5 per cent dextrose in RLS--without I.Y. administration set (Yialflex) One liter of 5 per cent dextrose in RLS--with LY. administration set (Yiaflex)
77
0 to 358
74
59 to 89
Legend: LV., Intravenous. RLS, Ringer's lactate solution.
oxygenator and the removal of the MFM was always accomplished under sterile conditions, the oxygenator was used for the operation as usual. The counts obtained in the various groups of oxygenators showed (Table I) that the Bentley Q 100 was the most highly contaminated: 130,046 (range 10,530 to 480,100). The Harvey H200 was second with a count of 39,598 (range 20,702 to 66,773); the Rygg was third, 23,730 (range 1,974 to 115,893); the Galen Optiflo was fourth, 5,719 (range 987 to 30,125); and the Travenol 6LF was fifth, 1,429 (range 239 to 4,248). The pediatric Travenol 2 LF had a count of 845 (range 299 to 2,812). This amount of contamination is approximately one half that of the adult oxygenator, but so is the size of the unit; therefore, the ratio of contamination is the same. Subsequent to our initial studies, the William Harvey Research Corporation produced an oxygenator (Model H200B) which provided an 81 per cent decrease in foreign body count, a considerable improvement. For comparison, 1 L. of 5 per cent dextrose with lactated Ringer's solution
Volume 68 Number 6 December, 1974
Particulate matter in bubble oxygenators
.
973
,.
Oxygenator
Fig. 2. Schematic drawing shows placement of the Millipore filter as utilized in the cardiopulmonary bypass circuit for rinsing and filtering the oxygenator.
Fig. 3. Photomicrograph of particulate matter. Cotton fiber and plastic chips are shown. (Original magnification x200.)
(Travenol) was passed through a given filter (Table II) . The particulate matter count was 77 (range zero to 358) when the solution passed through an intravenous administration set and 74 (range 59 to 89) when the solution was passed through the filter from the container. Although we did not attempt to establish accurately the nature of these particles, we found that approximately 86 per cent were fibers, 10 per cent plastic chips, and 4 per cent of undetermined nature (Fig. 3) (photomicrograph).
Discussion
When we consider that several thousand open-heart operations are performed daily in this country with the aid of oxygenators that have a relatively high foreign body content, it is not surprising that the incidence of neurologic deficits is significant. Until recently, postoperative neurologic complications have been attributed solely to air, fibrin, platelets , protein aggregates, fat, hypotension, and hypoperfusion. These findings as well as Gerecke's'" data show that
The Jaurnal of
974
Reed et al.
Thoracic and Cardiovascular Surgery
the size and composition of particulate matter flushed from bubble oxygenators can cause complete and permanent occlusion of finer blood vessels. This vascular occlusion could lead to infarction of the area supplied or to the establishment of collateral perfusion, depending upon where the particles become trapped. As Garvan and Gunner" demonstrated, granuloma formation is a distinct possibility. Before we began using this filtration technique, the incidence of neurologic deficits in our experience was 14.3 per cent in 692 open-heart procedures, including aorto-coronary bypass grafts, valve surgery, and surgery of congenital heart disease. This incidence has decreased with filtration to 10.7 per cent in 318 cases similarly distributed. Conclusion
Our simple filtration technique effectively removes vast amounts of foreign body material accumulated in bubble oxygenators and diminishes the incidence of neurologic deficits after cardiopulmonary bypass. Thus the technique helps to lessen the postoperative incidence of morbidity. We have incorporated the described filtration technique as a standard procedure in priming oxygenators for open-heart surgery. REFERENCES Helmsworth, J. A., Gall, E. A, Perrin, E. V., Braley, S. A, Flege, J. B., Jr., Kaplan, S., and Keirle, A. M.: Occurrence of Emboli During Perfusion With an Oxygenator Pump, Surgery 53: 177, 1963. 2 Lee, W. H., Jr., Krumhaar, D., Fonkalsrud, E. W., Schjeide, O. A., and Maloney, J. V., Jr.: Denaturation of Plasma Proteins as a Cause
of Morbidity and Death After Intracardiac Operations, Surgery 50: 29, 1961. 3 Wright, E. S., Sarkozy, E., Dobell, A R. C., and Murphy, D. R.: Fat Globulinemia in Extracorporeal Circulation, Surgery 53: 500, 1963. 4 Austen, W. G., and Howry, D. H.: Ultrasound to Detect Bubbles or Particulate Matter During Cardiopulmonary Bypass, J. Surg. Res. 5: 283, 1965. 5 Allardyce, D. 8., Yoshida, S. H., and Ashmore, P. G.: The Importance of Microembolism in the Pathogenesis of Organ Dysfunction Caused by Prolonged Use of the Pump Oxygenator, J. THORAC. CARDIOVASC. SURG. 52: 706, 1966. 6 Garvan, J. M., and Gunner, B: W.: The Harmful Effects of Particles in Intravenous Fluids, Med. J. Aust. 2: 1, 1964. 7 Osborn, J. J., Cohn, K., Hait, M., Russi, M., Salel, A., Harkins, G., and Gerbode, F.: Hemolysis During Perfusion, J. THORAC. CARDlOVASC. SURG. 43: 459, 1962. 8 Goldiner, P. L., Howland, W. S., and Ray, C., Jr.: Filter for Prevention of Microembolism During Massive Transfusions, J. Int. Anesth. Res. Soc. 51: 717,1972. 9 Connell, R. S., Page, U. S., Bartley, T. D., Bigelow, J. C., and Webb, M. C.: The Effect on Pulmonary Ultrastructure of Dacron-Wool Filtration During Cardiopulmonary Bypass, Ann. Thorac. Surg. 15: 217, 1973. 10 Spencer, M. P., Lawrence, G. H., Thomas, G. I., and Sauvage, L. R.: The Use of Ultrasonics in the Determination of Arterial Aeroembolism During Open-Heart Surgery, Ann. Thorac. Surg. 8: 489, 1969. II Kessler, J., and Patterson, R. H., Jr.: The Production of Microemboli by Various Blood Oxygenators, Ann. Thorac. Surg. 9: 221, 1970. I2 Patterson, R. H., Jr., and Kessler, J.: Microemboli During Cardiopulmonary Bypass Detected by Ultrasound, Surg, Gynecol. Obstet. 129: 505, 1969. I3 Gerecke, W. B., Crosthwait, R. W., and Angel, R. T.: Particulate Contamination in Cardiopulmonary Bypass: Importance of Delivery Systems and Intravenous Fluids. In press. 1973.