Count and Cardiotomy Suction Return

Transcription

1 Reltionship between Pltelet Count nd Crdiotomy Suction Return L. Henry Edmunds, Jr., M.D., Nresh C. Sxen, M.B.B.S., Priscill Hillyer, C.C:P., nd Terrnce J. Wilson, B.S. ABSTRACT A simple, inexpensive, ccurte method of mesuring the mount of blood returned by the crdiotomy suction system ws devised nd clibrted. Preopertive nd postopertive pltelet counts were obtined in 76 ptients with congenitl hert disese in whom the mount of crdiotomy suction return ws mesured. The men percentge of totl perfuste returned by the crdiotomy suction system ws 8.9%. Both postopertive pltelet count nd the percentge chnge between preopertive nd postopertive pltelet counts correlted with the mount of blood returned by the crdiotomy suction system, time on bypss, nd the percentge of totl perfuste spirted by the system. Crdiopulmonry bypss cuses 4 to 6% decline in pltelet count 1191 nd decreses pltelet function [9,15,19]. The lower count occurs immeditely nd is due to dilution of the ptient s blood with priming solutions, interction between pltelets nd foreign surfces [9, 141, formtion of microggregtes [l, 71, nd possibly sequestrtion of some pltelets by the reticuloendothelil system [4]. The crdiotomy sucker system is mjor source of hemolysis [5, 12,13,17] nd prticulte emboli [lo, 181 during crdiopulmonry bypss nd my further decrese pltelet numbers by direct trum, ggregtion, nd filtrtion. The present work ws designed to study the reltionship between pltelet numbers nd the volume of crdiotomy suction return during crdiopulmonry bypss in ptients. The effect of crdiotomy suction on pltelets hs not been previously studied, prtly From the Deprtment of Surgery, Children s Hospitl of Phildelphi nd the University of Pennsylvni, Phildelphi, PA. Supported in prt by Grnt HL1955, Ntionl Hert, Lung, nd Blood Institute, Ntionl Institutes of Helth. Accepted for publiction Sept 13, Address reprint requests to Dr. Edmunds, Children s Hospitl of Phildelphi, 34th St nd Civic Center Blvd, Phildelphi, PA becuse of difficulties in mking ccurte mesurements of spirted blood mixed with ir. Methods Mesurement of Crdiotomy Suction Return The crdiotomy sucker system consists of brely occlusive roller pumps nd polycrbonte filter-reservoir (Model 423, Cobe Lbortories, Lkewood, CO) which empties into the venous end of conventionl bubble oxygentor (Bentley Lbortories, Inc, Snt An, CA) or the reservoir bg of membrne oxygentor system. For children over 12 kg nd for dults, 3/s-inch ID polyvinyl tubing is used. For infnts, %-inch ID tubing is used. Two photocells re mounted on polycrbonte plte with centers plced 5 mm prt in the verticl direction (Fig 1). To minimize the mount of blood held in the reservoir, the bottom photocell is tped just bove the bottom edge of the side pnel. The photocells re connected to n electric clmp (Fisher Scientific Co) nd to digitl electric timer (ETHM-16, Keffler-Ellis Products, Atlntic Highlnd, NJ*). When ccumulted blood in the reservoir ctivtes the upper photocell, the electric clmp opens nd the timer strts. Blood drins to the level of the lower photocell, which closes the electric clmp nd stops the timer. The system mintins the reservoir blood level between the two photocells nd ccumultes the time during which the reservoir drins. Approximtely 13 ml of blood is held between the two photocells nd nother 5 ml is held between the bottom photocell nd the reservoir outlet. Air does not enter the outlet tubing. The system must be clibrted to convert the seconds the clmp is open into milliliters of blood. Clibrtion vries with the size of the outflow tubing of the crdiotomy filter-reservoir nd the effective hydrosttic pressure hed. An *Mde by Chrles F. Wrd, Hibemi Rd, Cotesville, PA by L. Henry Edmunds, Jr.

2 37 Edmunds et l: Pltelet Count nd Crdiotomy Suction Return Cordiotomy Reservoir Automtic 'lmp Fig I. System for mesurement offield-spirted blood. Photosensors re ttched to commercil filterreservoir control, n electricl outflow clmp, nd digitl clock. The svstem is clibrted t known effective hydrosttic pressure to ssure reproducible mesuremen ts. effective hydrosttic pressure hed of 25 cm H2 produces convenient rte of blood flow. With the membrne oxygentor system the venous reservoir produces no bck-pressure. Bckpressure within the Bentley oxygentor vries with the rtio of gs flow to blood flow but chnges less thn 1 cm H,O t recommended flow rtes if the gslblood flow rtio is 2. Therefore the bottom photocell on the filter-reservoir is plced 25 cm higher thn the mesured bckpressure t the inlet of the Bentley oxygentor. The mount of blood in the oxygentor does not pprecibly ffect bck-pressure. Reproducibility of clibrtion mesurements, the effect of chnges in hemtocrit, nd reppliction of photocells were tested for both %-inch ID nd %-inch ID tubing (9.5 nd 6.4 mm, respectively). Blood nd ir spirted by the system were collected in grduted cylinders held 25 cm below the outlet of the filter-reservoir. Timed collections rnged from 3.8 to 31.4 seconds nd from 12 to 975 ml, nd were mde on four different dys. Pltelet Studies Pltelets were counted by phse microscopy. Pltelet counts were obtined before opertion, fter stopping crdiopulmonry bypss, nd before trnsfusions. Mesurements were mde in 76 ptients ged 8 dys to 17 yers nd weighing 3.8 to 5 kg. Sixteen weighed less thn 12 kg. All hd congenitl hert disese, nd 33 were cynotic. The dignoses were tril septl defect nd vrints, including prtil trioventriculr cnl nd totl nomlous pulmonry venous connection, in 18 ptients; ventriculr septl defect nd vrints, including double-outlet right ventricle, in 15 ptients; ortic nd pulmonry stenosis in 4 ptients ech; trnsposition of the gret rteries in 7 ptients; vlve insufficiency necessitting replcement in 3 ptients; nd tetrlogy of Fllot nd vrints, including pulmonry tresi, in 25 ptients. The perfusion system included disposble bubble oxygentor (Bentley Lbortories), cnnulted flowmeter, nd n rteril line filter (Pll Ultipore Blood Filter, Glen Cove, NY). All blood from the left ventriculr ctheter nd two crdiotomy suckers entered the crdiotomy suction system. The bypss system ws primed with citrte-phosphte-dextrose blood less thn five dys old nd Ringer's lctte solution clculted to produce hemtocrit of 3 in ptients weighing 25 kg or less nd hemtocrit of 25 in ptients more thn 25 kg. Finl pltelet count, chnge in pltelet count, nd percent chnge in pltelet count were compred to volume of crdiotomy suction return, percentge of totl perfusion flow spirted by the crdiotomy suction system, nd durtion of bypss. These comprisons were lso mde for the following subgroups: 33 cynotic ptients, 43 cynotic ptients, 11 perfused with the infnt oxygentor (Model Q 13), 55 perfused with the peditric oxygentor (Model Q 11), nd 1 perfused with the dult oxygentor (Model Q 2A). The peditric group ws further divided into cynotic nd cynotic ptients for nlysis. Results Clibrtion of Crdiotomy Suction Mesurements At n effective hydrosttic pressure hed of 25 cm H2, only tubing size ltered the men conversion fctors significntly (Tble 1). Regres-

3 38 The Annls of Thorcic Surgery Vol 25 No 4 April 1978 sion equtions with flow plotted s function of time nd correltion coefficients between flow nd time re given in Tble 1. The men conversion fctor for %-inch tubing ws 15.2 ml per second with stndrd devition of 1.4 (N = 59); for %-inch tubing the fctor ws 3.9 ml per second, SD 1.9 (N = 11). Volume of Crdiotomy Suction Return The mount of field-spirted blood vried widely mong ptients nd rnged from 66 ml to 57 liters. The lrgest volumes were recorded in ptients with cynotic hert disese who hd lrge bronchil vessels. The percentge of totl blood perfused (flowlmin x durtion of bypss) spirted by the crdiotomy suction system vried from 1.5 to 25.3%. In 33 cynotic ptients men of 1.6% of the totl blood perfused returned by the crdiotomy suction system nd left ventriculr vent. In 43 cynotic ptients the men ws 7.6%. kt $ 15 $ * Ix)- 4u *. O ' O i ' I I ' Percent of Perfusle AsDiroted Fig 2. Reltionship between postopertive pltelet count (in thousnds) nd percentge of totl blood perfused tht ws returned by the crdiotomy suction system. Pltelet Studies Pltelet counts fter bypss (men, 9,) correlted inversely with the mount of blood returned by the crdiotomy suction system (men, 13.7 liters), with the percentge of totl blood perfused tht ws spirted (men, 8.9%) (Fig 2), nd with the durtion of bypss (men, 78.6 min) (Tble 2). The difference between preopertive nd postopertive pltelet counts (men, 186,) did not correlte significntly with the sme vribles (correltion coefficients,.6 to.1). However, the percentge difference in preopertive nd postopertive pltelet counts (men, 66%) did (Fig 3). Neither the size of the oxygentor nor the presence or bsence of cynosis ffected these correltions. Comment The crdiotomy suction system is the mjor cuse of hemolysis during crdiopulmonry bypss [5, 12, 13, 171 nd the min source of prticulte emboli [lo, 181. Previous studies hve shown direct reltionship between hemolysis nd blood contct with pericrdil nd pleurl surfces [161, physicl stresses t the sucker tip [12, 171, nd the mount of negtive pressure within the system [ll, 171. Extrcor- Tble I. Clibrtion of Crdiotomy Suction System Inner Men Conversion Regression Dimeter of Fctor f SD Eqution Correltion Tubing (in.) Hemtocrit N (mysec) 9 (ml) = + b (sec) Coefficient k I k N = number of mesurements.

4 39 Edmunds et l: Pltelet Count nd Crdiotomy Suction Return Tble 2. Results of Pltelet Studies Regression Eqution Regression Determintion Q=+bx Coefficient k SE Significnce Postopertive pltelet count (y) vs suction volume (L) (x) ~ -.26 f.492 p <.5 Postopertive pltelet count (y) vs percent perfuste spirted (x) ~ -.38 f p <.1 Postopertive pltelet count (y) vs bypss time (min) (x) ~ -.39 k.151 p <.1 Percent difference in pltelet count (y) vs suction volume (L) (x) ~.23 f.177 p <.5 Percent difference in pltelet count (y) vs ~.36 k.415 p <.1 percent perfuste spirted (x) Percent difference in pltelet count (y) vs ~.25 k.57 p <.5 bypss time (min)(x) porel circultion dmges nerly ll formed nd unformed blood elements to some degree. Since the crdiotomy suction system is the mjor cuse of hemolysis, it follows tht the system might lso cuse dditionl dmge to pltelets. This hypothesis hs not been studied before, prtly becuse of difficulties in ccurtely mesuring crdiotomy suction return nd prtly becuse pltelet counts vry widely fter crdiopulmonry bypss [15, 191. Fig 3. Reltionship between percentge chnge in preopertive nd postopertive pltelet counts nd percentge of totl blood perfused tht ws returned by the crdiotomy suction system. 1 tl/ '"I 2ot ** 9.s 5o. 6. * * *. * :. # O - * 8.* 2. 8 **.. Initilly we compred pltelet counts in extrcorporel venous blood nd blood spirted simultneously by the crdiotomy suction system. No consistent differences in pltelet counts were found, probbly becuse smll differences were msked by vritions due to counting technique. Tht pproch ws bndoned in fvor of the present study, which shows sttisticlly significnt correltion of both postopertive pltelet count nd percent difference in pltelet count with the mount of crdiotomy suction return, bypss time, nd percentge of totl perfuste spirted by the suction system. As mentioned in the introduction, the cuses of pltelet dmge during crdiopulmonry bypss re resonbly well estblished. Tissue nd ir contct nd incresed physicl stress within the suction system increse pltelet ggregtion nd relese [6, 81. Filtrtion further reduces pltelet numbers by removing ggregtes nd pltelet debris E7, 181. As with red cells, these fctors best explin the dditionl pltelet losses cused by the crdiotomy suction system. The mount of blood spirted by the left ventriculr vent nd the crdiotomy suckers is lrge, nd the ide of discrding such blood [16,2] is not prcticl. Such policy requires dditionl trnsfusions of bnked blood, which lso hs few functioning pltelets. A better pproch is to try to limit the mount of crdiotomy suction return by using hypothermic nd low-flow techniques during prts of the opertion, reduc-

5 31 The Annls of Thorcic Surgery Vol 25 No 4 April 1978 ing the mount of ir spirted with the left ventriculr vent, nd reducing bypss time. The bility to mesure the mount of crdiotomy suction return during opertion gives the surgeon n opportunity to reduce the mount of blood spirted by the system. Although others hve devised wys of mesuring the mount of crdiotomy suction return [3], the system described here is relible, inexpensive, ccurte, nd simple to operte. Mesurements cn be mde t ny time intervls during opertion. Those using the system should mke their own clibrtion mesurements t known effective hydrosttic pressure, which is then kept constnt whenever the system is used. The system cn be improved for infnts nd young children by using filter-reservoir with smller outflow chmber. The smller chmber reduces the mount of blood held between the two photocells s well s tht between the bottom photocell nd the outlet. Hemolysis rrely cuses postopertive problems fter modern bypss opertions, but thrombocytopeni nd poor pltelet function cuse poor clot formtion [21 nd prolonged bleeding times [3] in the mjority of ptients fter bypss. The crdiotomy suction system contributes to this problem but is not the primry cuse. When mens re found to preserve pltelet numbers nd function during bypss, the time spent fter bypss in securing hemostsis will be mterilly reduced. References 1. Ashmore PG, Suitek V, Ambrose P: The incidence nd effects of prticulte ggregtion nd microembolism in pump-oxygentor systems. J Thorc Crdiovsc Surg 55:591, Bchmnn F, McKenn R, Cole ER, et l: The hemosttic mechnism fter open-hert surgery. J Thorc Crdiovsc Surg 7:76, Benzing G 111, DeForest D, Kpln S: Multipleline single-reservoir utomtic crdiotomy blood return system. J Thorc Crdiovsc Surg 51:238, de Lev1 M, Hill JD, Mielke CH Jr, et l: Blood pltelets nd extrcorporel circultion: kinetic studies on dogs on crdiopulmonry bypss. J Thorc Crdiovsc Surg 69:144, Donld DE, Hrshbrger HG, Kirklin JW: Studies in extrcorporel circultion: 11. A method for the recovery nd the use of blood from the open hert during extrcorporel circultion in mn. Ann Surg 144:223, Dutton RC, Edmunds LH Jr: Formtion of pltelet ggregte emboli in prototype hollow fiber membrne oxygentor. J Biomed Mter Res 8:163, Dutton RC, Edmunds LH Jr, Hutchinson JC, et l: Pltelet ggregte emboli produced in ptients during crdiopulmonry bypss with membrne nd bubble oxygentors nd blood filters. J Thorc Crdiovsc Surg 67:258, Goldsmith HL, Yu SSK, Mrlow J: Fluid mechnicl stress nd the pltelet. Thromb Dith Hemorrh 34:32, Hennessy V, Hicks RE, Niewirowski S, et l: Effects of surfce re nd composition on the function of humn pltelets during extrcorporel circultion. Am J Physiol232:H622, Hill JD, Osborn JJ, Swnk RL, et l: Experience using new Dcron wool filter during extrcorporel circultion. Arch Surg 11:649, Hirose T, Burmn SO, O Connor RA: Reduction of perfusion hemolysis by the use of trumtic low-pressure suction. J Thorc Crdiovsc Surg 47:242, Indegli RA, She MA, Vrco RL, et l: Mechnicl nd biologic considertions in erythrocyte dmge. Surgery 62:47, Keith HB, Ginn E, Willims GR, et l: Mssive hemolysis in extrcorporel circultion. J Thorc Surg 41:44, Lymn DJ, Brsh JL, Chikin SW, et l: The effect of chemicl structure nd surfce properties of synthetic polymers on the cogultion of blood: 11. Protein nd pltelet interction with polymer surfces. Trns Am Sc Artif Intern Orgns 14:25, 1968 McKenn R, Bchmnn F, Whittker B, et l: The hemosttic mechnism fter open hert surgery. J Thorc Crdiovsc Surg 7:298, 1975 Morris KN, Kinross FM, Stirling GR: Hemolysis of blood in the pericrdium: the mjor source of plsm hemoglobin during totl body perfusion. J Thorc Crdiovsc Surg 49:25, 1965 Osborn JJ, Cohn K, Hit M, et l: Hemolysis during perfusion. J Thorc Crdiovsc Surg 43:459, 1962 Osborn JJ, Swnk RL, Hill JD, et l: Clinicl use of Dcron wool filter during perfusion for openhert surgery. J Thorc Crdiovsc Surg 6:575, 197 Slzmn EW: Blood pltelet nd extrcorporel circultion. Trnsfusion 3:274, 1963 Siderys H, Herod GT, Hlbrook H, et l: A comprison of membrne nd bubble oxygention s used in crdiopulmonry bypss in ptients. J Thorc Crdiovsc Surg 69:78, 1975