Heparin therapy

Monitoring of subcutaneous dalteparin in patients with renal insufficiency under intensive care: an observational study

OBJECTIVE

The objective of this study was to investigate the pharmacodynamic parameters of dalteparin in patients with renal insufficiency under intensive care.

MATERIALS AND METHODS

In this open, nonrandomized, nonblinded, prospective, single-dose observational study, 10 critically ill patients with renal insufficiency (mean creatinine clearance = 29.5 +/- 6.42 mL/min) were administered a single 5000-IU subcutaneous dose of dalteparin.

RESULTS

Dalteparin blood levels were estimated indirectly over a 12-hour period by measuring anti-Xa activity and by performing a clotting assay known as the ATHU (AHEPA Thrombosis and Hemostasis Unit) test. Maximum anti-Xa activity (ie, 0.42 +/- 0.13 IU/mL) was achieved 4 hours after administration (in 8 of 10 patients). Adequate anticoagulant activity was maintained throughout the 12-hour dosage interval in all study patients. However, at time 0 hour of the study, 36 hours after the administration of a previous dose of dalteparin, considerable anti-Xa activity (ie, 0.39 +/- 0.11 IU/mL) was measured in 6 patients. A good correlation was found between anti-Xa activity and the results of the ATHU test.

CONCLUSIONS

The presence of medium/severe edema and the concurrent administration of 1 to 3 inotropic drugs appear to contribute to a decrease in the rate of elimination of dalteparin, resulting in a greater-than-expected (as a result of decreased renal function) prolongation of its pharmacologic activity. We recommend that care be taken with repeated dosing of dalteparin in intensive care unit patients taking inotropic drugs until observed results can be confirmed.

Activated clotting time as a screening test prior to catheter-based cardiovascular procedures

The activated clotting time (ACT) was investigated as a rapid, inexpensive, point-of-service screening test for coagulation abnormalities prior to catheter-based procedures. A total of 963 patients were screened by obtaining a history, standard coagulation profile, and activated coagulation time. The prevalence of normal patients (normal ACT and coagulation profile) was 94% (sensitivity = 91%; specificity = 27%). A normal ACT had a positive predictive value of 95%. The ACT was an acceptable screening test due to its ability to predict positively a low rate of bleeding complication and normal coagulation studies. Patients with ACT > 150 sec should be further evaluated with a screening coagulation panel. Additionally, given its low specificity, coagulation studies should be obtained in high-risk patients since an abnormal ACT does not effectively correlate with abnormal coagulation studies.

Use of heparin in the treatment of protein-losing enteropathy after fontan operation for complex congenital heart disease

Protein-losing enteropathy (PLE) is a serious complication of the Fontan operation and is associated with pronounced mortality. Medical management of PLE has been only partially successful. A recent report noted dramatic improvement in patients with PLE within 3 weeks of subcutaneous administration of heparin. We report a case of reversal of PLE with resolution of clinical symptoms and normalization of serum albumin, total protein, and fecal alpha1-antitrypsin values after several months of heparin treatment. Our findings substantiate those recently reported but suggest that reversal of PLE may necessitate more than a few weeks of heparin therapy.