System speeds aPTT results

Care of patients with acute coronary syndromes centers around minimizing the opportunity for thrombus formation in the coronary artery. Standard therapy usually includes I.V. heparin administration, in addition to other pharmacologic agents to dissolve clots and prevent platelet aggregation.

Current research suggests that outcomes could be improved and bleeding complications minimized if "therapeutic" levels of anticoagulants were reached in a more timely manner. One major obstacle in obtaining these levels is turnaround times that can average up to two to four hours for activated partial thromboplastin times (aPTT) from central labs.

Excessive turnaround times for aPTT can delay access from the nursing and medical staff to those results, impeding clinicians' ability to make timely clinical decisions. What's more, increased patient length of stay and the number of patients who don't achieve a therapeutic level of anticoagulation may lead to an increase in the extent of bleeding and number of vascular events.

Fortunately, technology now exists that enables APTTs to be performed at the point of care (POC), providing healthcare providers with immediate results. These devices, of course, must comply with appropriate regulations (see Abiding by regulations).

POC versus the lab

At The Cleveland Clinic Foundation, we compared portable bedside coagulation tests using whole blood coagulation with standard lab plasma coagulation tests to assess the sensitivity, accuracy, and ease of performance of the bedside instruments. One instrument we chose for its capacity to monitor heparin therapy by aPTT methodology on whole blood at the bedside was the Ciba Corning 512 Coagulation Monitor, also called the CoaguChek Plus (Roche Diagnostics Corp., Indianapolis, IN).The handheld, battery-operated device can determine aPTTs from whole blood capillary or venous samples.

With a warm-up time of 45 seconds, the 1.2-lb CoaguCheck Plus can perform 20 to 30 tests per hour. Users follow a three-step testing procedure and results are delivered in less than three minutes. The system can also test for PT.

The aPTT results from this instrument were compared with standard lab plasma aPTT values. We sought to evaluate the difference in normal range and correlation between lab aPTT and the POC instrument using both venipuncture and fingerstick methods. Heparin dose-response comparisons and precision and reliability studies were also performed. We found a high correlation between the lab aPTT values and POC instrument values.

What's more, we studied two patient groups cared for under these monitoring systems. We studied 694 patients undergoing percutaneous transluminal coronary angioplasty at our institution over 12 consecutive months. Some 466 patients were cared for with aPTT assessed by the central lab, while 228 patients were monitored with bedside POC testing. We observed no difference in clinical in-hospital outcome between the two groups with respect to Q-wave myocardial infarction, stroke, death, acute closure, transfusion, and hematoma. POC testing reduced length of stay by 22% and cost per case by 15%.

After this evaluation, POC testing for routine management of anticoagulation was implemented as a 6-month pilot program throughout the Department of Cardiac Nursing at The Cleveland Clinic Foundation. We continue to use POC testing at Cleveland Clinic for managing all anticoagulation with heparin.

Institutions implementing decentralized POC testing need to comply with regulations from three sources:

1. Health Care Financing Administration
2. College of American Pathologists
3. Joint Commission on Accreditation of Healthcare Organizations

Institutions also need to check with their state regulatory agencies to determine whether those standards are more stringent than standards from the national agencies. If so, institutions must establish practices that comply with the state agencies' specifications.