Colleen Gruenwald, PhD, MHSc, RN, CCP, CPC, a Medtronic consultant, addressed clinicians on the clinical impact of changes made to unfractionated heparin (UFH) at the recent 35th Annual Cardiothoracic Surgery Symposium, held in San Diego.
As reported previously, the U.S Food and Drug Administration (FDA) mandated a change to the heparin monograph in 2009 that brought the USP heparin standard in line with the international standard used by the World Health Organization. Since then, an approximate potency reduction of 10% has been reported by the FDA and in subsequent studies.1 Heparin remains the anticoagulant of choice to counteract the physiologic response to the non-endothelial surface of the cardiopulmonary bypass (CPB) system.
The need for larger heparin doses to achieve the desired anticoagulation effect has prompted retrospective and prospective studies in both pediatric and adult patients. Authors of recent studies noted that in addition to the 12% increase in the required heparin loading dose, significantly fewer patients in the "new heparin group" achieved an activated clotting time (ACT) > 480 seconds prior to bypass.2,3,4
Gruenwald noted that "with this potency change, there are additional variables that increase the complexity of anticoagulation dosing and monitoring, including:
With the FDA website stressing that, "Heparin dosing is individualized based on patient-specific considerations, given clinical dosing of heparin already varies among patients," Gruenwald reminded clinicians that monitoring anticoagulation should be frequent and individualized for each patient.
The updated guidelines are meant to reduce bleeding and blood product usage in patients undergoing CPB for cardiac surgery. For short routine cases, the guidelines recommend monitoring the anticoagulation state by using at a minimum the activated clotting time (ACT). For longer cases (> 2-3 hours), the guidelines recommend maintaining a higher and/or patient-specific heparin concentration, which can be achieved by monitoring the heparin dose response (HDR) and the heparin protamine titration (HPT) with the Medtronic HMS Plus Hemostasis Management System.
The guidelines also suggest using the HPT or empiric low dose regimens to lower the total protamine dose, as well as the protamine-to-heparin ratio at the end of bypass. Therefore, these guidelines support using point-of-care HDR and HPT tests during CPB.
Gruenwald underscored the importance of being informed and educated, adding practical reminders such as:
"Enhanced anticoagulation management and monitoring may reduce hemostatic activation, consumption of coagulation proteins, in addition to bleeding and the subsequent need for blood transfusions," observed Gruenwald. "This is an extremely important goal based on recent publications that have shown an increased risk in morbidity and mortality among patients who have received blood transfusion during or following heart surgery."10
Anderson DA, Holt DW. Has the new USP assay for heparin affected dosage for patients undergoing cardiopulmonary bypass. J Extra Corpor Technol. 2013; 45:112-5.
Guzzetta NA, Amin SJ, Tosone AK, Miller BE. Change in the heparin potency and effects on the activated clotting time in children undergoing cardiopulmonary bypass. Anesth Analg. 2012; 115:921-4.
Thompson K, Allred J, Deyo A, Sievert AN, Sistino JJ. Effect of New Heparin Potency on Activated Clotting Time during Pediatric Cardiac Surgery: A Retrospective Chart Review. JECT. 2014; 46:224-228.
Arsenault KA, Paikin JS, Hirsh J, Dale B, Whitlock RP, et al. Subtle differences in commercial heparins can have serious consequences for cardiopulmonary bypass patients: A randomized controlled trial.J Thorac Cardiovasc Surg. 2012 October; 144(4):944-950.
Gruenwald CE, Manlhiot C, Abadilla A, Kwok J, Maxwell S, et al. Heparin brand is associated with immediate postoperative outcomes in children undergoing cardiac surgery with cardiopulmonary bypass. Ann Thorac Surg. 2011.
Finely A, Greenberg C. Heparin Sensitivity and Resistance: Management During Cardiopulmonary Bypass. Society of Cardiovascular Anesthesiologists, Review Article. June 2013; Volume 116, Number 6 www.anesthesia-analgesia.org
The Society of Thoracic Surgeons Blood Conservation Guideline Task Force: Ferraris VA, Brown JR, Despotis GJ, Hammon JW, Reece TB, et al. 2011 Update to The Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists Blood Conservation Clinical Practice Guidelines. Ann Thorac Surg. 2011;91:944-82.
Baker RA, Bronson SL, Dickinson TA, Fitzgerald DC, Likosky DS, et al. Report from AmSECT's International Consortium for Evidence-based Perfusion: American Society of ExtraCorporeal Technology Standards and Guidelines for Perfusion Practice. JECT 2013; 45:156-166.
Koch CG, Liang Li, Sessler DI, Figueroa P, Hoeltge GA, et al. Duration of Red-Cell Storage and Complications after Cardiac Surgery. N Engl J Med. 2008; 358:1229-39.