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Perfusing the Jehovah's Witness Patient with Heparin-Induced Thrombocytopenia

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Perfusing the Jehovah's Witness Patient with Heparin-Induced Thrombocytopenia THE jOURNAL OF EXTRA-CORPOREAL TECHNOLOGY Case Report Perfusing the jehovah's Witness Patient with Heparin-Induced Thrombocytopenia D. Mark Brown, BS, CCP Heart Institute of Spokane, Spokane, Washington Keywords: heparin-induced thrombocytopenia, low-molecular weight heparin, Jehovah's Witness, cardiop­ ulmonary bypass ABSTRACT Heparin-induced thrombocytopenia (HIT) is an uncommon, yet dangerous side-effect of heparin therapy. The problems associated with the HIT patient while undergoing cardiopulmo­ nary bypass increase dramatically when the patient is also of Jehovah's Witness faith. This case report depicts the techniques utilized and the decisions made over the course of a simple surgical procedure for an extremely high-risk patient. Address correspondence to: D. Mark Brown, BS, CCP Heart Institute of Spokane 444 W. 25th Avenue Spokane, WA 99203 Volume 30, Number 4, December 1998 193 THE JOURNAL OF EXTRA-CORPOREAL TECHNOLOGY INTRODUCTION CASE MANAGEMENT Heparin-induced thrombocytopenia (HIT) is an extremely The patient arrived in the operating room in stable condi­ rare, yet highly dangerous side effect of heparin therapy. For tion, placed under general anesthesia, prepared and draped for those patients undergoing major, high-risk surgery involving surgery in the normal sterile fashion. A median sternotomy was cardiopulmonary bypass (CPB), the risks increase dramatically. performed while saphenous vein was harvested and prepared for Although thrombocytopenia can be effectively managed post­ grafting. The patient was then systemically anti-coagulated with operatively, every effort must be made to maximize patient out­ 60mg Lovenoxa (enoxaparin sodium), which was administered come. This is particularly true regarding patients of Jehovah's via the central line into the right atrium (RA). A blood sample Witness faith. was taken and measured for activated clotting time (ACT)h. With Traditionally, non-fractionated heparin of porcine or bovine a baseline ACT measurement of 117 seconds, a post-anti-coagu­ origin has been the anti-coagulant of choice for CPB. However, lation ACT of >800 seconds was obtained prior to cannulation. little research and clinical data has been produced for those clini­ An 18F aortic root cannula was placed in the proximal aorta and cal scenarios where non-fractionated heparin is not a viable op­ a 42F, two-stage venous cannula was placed in the RA and se­ tion. cured with purse-string sutures. In order to minimize hemodilution, the normally-used ex­ CASE DESCRIPTION tra-corporeal circuit (ECC) was customized. Changes included switching to a venous reservoir and oxygenator with lower prim­ ing volumes, reducing line lengths, and eliminating the arterial A 61 year old female of Jehovah's Witness faith presented line filter (ALP)". Elimination of the ALP served two purposes: with severe multi-vessel coronary artery disease (CAD), insu­ to minimize hemodilution and to avoid unnecessary heparin ex­ lin-dependent diabetes mellitus (IDDM), a history significant for posure, as the ALP's at our institution are heparin coated. The seizure activity, acute anterior myocardial infarction, and dia­ ECC had one additional modification to accommodate an an­ betic ketoacidosis with subsequent coma for which she required ticipated poor venous return: a centrifugal pump headct. This intubation and respiratory support. pump was placed on a 3/8 "venous line as a precautionary mea­ The patient was admitted to the hospital while anti-coagu­ sure to augment venous return. Due to the low-molecular weight lation options were reviewed and analyzed. After an extensive of Lovenox (~4500 Daltons), the decision was made by the per­ review of literature and research, the decision was made to pro­ fusion team to exclude any hemofiltration device from the ECC. ceed with coronary artery bypass grafting (CABG) using low­ Additionally, the decision was made to avoid heparin-bonded molecular weight (LMW) heparin. Laboratory testing was per­ circuits, as variable amounts of washout has been reported. The formed with the patient reacting only mildly to the LMW hep­ modified CPB circuit resulted in a priming volume of approxi­ arin. Additionally, the decision for concurrent Prostacyclin mately 1650mls. The prime consisted of 700ml Lactated therapy (50ng/kg/min) was made to minimize the effects and Ringer's (LR) solution, 700ml Hespan (Hetastarch 6 %), 50mEq reactivity of the LMW heparin on platelets (1). The patient's pre­ sodium bicarbonate, 50g mannitol, 1000mg cefazolin, 40mg operative blood work was essentially normal with the exception Lasix, and 60mg Lovenox. of an elevated glucose value of 312 mg%. Pre-operative lab After an ACT >800 sec was obtained, the patient was placed values were Hgb 13.1g/dL, Hct 38.8%, Na+ 138mEq/L, K+ on CPB and maintained at normothermic temperatures. The 4.1mEq/L, Pit 140, BUN 6.0mg/dL, CREAT0.7mg/dL,PT 13.8 aorta was cross-clamped and 600ml of 1:1 blood:crystalloid car­ sec, PTT 30.0 sec, BT 3.0 min. The day of surgery the patient's dioplegia was delivered at 4QC to the aortic root via a 1OG needle. weight was 60kg yielding a body surface area (BSA) of 1.62 Cardioplegic pressures were maintained at 80-lOOmm Hg. A myocardial temperature of 9QC was obtained before discontinu­ Upon cardiac catheterization, the patient was found to have ing cardioplegia and venting the aorta. severe triple-vessel CAD with a totally occluded right coronary The first arterial blood gas (ABG) sample and ACT was artery and sub-total occlusion of the left anterior descending, drawn from ECC approximately 10 minutes after initiation of ramus, and obtuse marginal arteries. The patient's ejection frac­ bypass. The resultant values were: pH 7.51, pC0 28mmHg, tion was calculated to be 45%. During hospitalization, it was 2 p0 461mmHg, Hgb 8.2g/dL, SAT 97%, base excess (BE) discovered that the patient had developed a heparin-induced 2 0.8mEq/L, HC03 23mEq/L, K+ 3.9mEq/L, GLU 220mg%, and thrombocytopenia. Heparin was then discontinued and the an ACT measurement of 180sec. Adjustments to correct ABG patient's platelet levels returned to normal. values were made and anti-coagulation status assessed. While reviewing anti-coagulation options with institutional pharmacist, the surgeon was notified and a second ACT was measured. The a Rhlne-Poulenc Rorer Pharmaceuticals, Inc., Colleyville, PA 19426 resulting ACT value was 149seconds. An additional loading b International Technidyne Corp., Edison, NJ 08820 c Medtronic Cardiopulmonary, Inc., Anaheim, CA 92807 dose of 60mg of Lovenox was given via the ECC. The circuit d Sarns 3M Healthcare, Ann Arbor, Ml 48103 was visually examined for clots and a third ACT was then taken 194 Volume 30, Number 4, December 1998 THE jOURNAL OF EXTRA-CORPOREAL TECHNOLOGY and measured to be 144 seconds. Visual signs of clotting were major vascular surgery requiring CPB, nor should it discourage seen in the venous reservoir and an additional 90mg Lovenox the medical community from providing treatment plans for such was administered via the ECC. The surgeon was again notified individuals. and prompted to terminate CPB as soon as possible. After a Prior to any major surgical procedure, all viable options fourth intra-operative ACT measurement of 204 seconds, a fi­ must be taken into consideration. First and foremost in this de­ nal dose of 90mg of Lovenox was given. A second ABO and cision-making process is to establish which method of anti-co­ additional ACT were taken after 32 minutes on bypass. ABO agulation will best suit the needs of the patient. At the present results were all within normal parameters and a peak ACT value time, possible options include: to continue using the traditional of 242 seconds was achieved. form of anti-coagulation (i.e. unfractionated heparin of bovine After 30 minutes, the aortic cross clamp was removed and or porcine origin) or to continue with non-traditional anti-co­ lOOmg Lidocaine and 1g calcium chloride were given via the agulation regimens (i.e. Hirudin, Ancrod, or Low-Molecular ECC. The heart immediately achieved normal sinus rhythm and Weight Heparin alternatives). CPB was terminated. A small dose of Protamine was given, a There is only a handful of clinical data available regarding total amount of 100mg, bringing the ACT down to an accept­ these non-traditional regimens. Hirudin , the most potent known able value of 130 seconds. Venous and arterial cannulae were thrombin-inhibitor, is derived from leeches (3). The primary removed with the ECC contents aspirated into the cell-washing advantage of Hirudin is that it is a direct thrombin inhibitor. That autotransfusion device for rapid transfusion back to the patiente. is, it does not require anti-thrombin III as a cofactor. Ancrod is Upon decannulation, the entire ECC was emptied out and visu­ a defibrinogenating agent which is derived from snake venom, ally inspected for clots distal to the venous reservoir. There were but little data is currently available to prove Ancrod useful or no signs of clotting within the arterio-venous loop, indicating advantageous as an anti-coagulant for CPB (4). Unfortunately, that existing clots were confined to the venous cardiotomy fil­ neither Ancrod nor Hirudin are currently available in the United ter. States. Low Molecular Weight or fractionated heparin is clas­ The patient received a total of three vein grafts, with every sified as an anti-thrombotic agent and has become increasingly anastomoses being completed utilizing a single-clamp technique. popular among clinicians in cases where traditional unfraction­ The surgical team was able to keep the total CPB period to 33 ated heparin is not an option. minutes. The patient was hemodynamically stable with a Once the issue of anti-coagulation has been resolved, the baseline electrocardiogram (ECO), no ST segment elevations, perfusionist is faced with the challenge of customizing a circuit cardiac index of approximately 2.4l/min/m2 and systolic blood to the needs of his or her patient.
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