What Is the Best Time to Initiate Peri-Operative Heparin Therapy In General Surgery Patients? A Risk-Benefit Dilemma.

While many studies support the use of prophylactic heparin therapy around the time of operation in cancer patients, little data shows the optimal timing of such therapy in general surgery (GS) patients.

From 2001–2008, 95 patients identified with thromboembolism reported in our GI/General Surgery Division and were compared with a matched control group for: age, gender, type of operation, date of operation, diagnosis of malignancy, and BMI. Timing of heparin therapy, characteristics of TE or bleeding events, driving distance from our institution, history of smoking or OCP use, anticoagulation use after operation, length of hospital stay, and mortality were collected. Peri-operative heparin therapy was defined as heparin given within a 24 hr window of incision. The McNemar's test for proportions was performed. Conditional logistic regression was used for the analysis of risk factors and survival curves were implemented for mortality comparisons.

mean age and BMI were similar (57 yrs, 33 kgM^-2), 45% were female and 53% had malignancy in both groups. Duration of operation was similar (204 vs. 191 minutes, P=NS). peri-operative heparin administration was similar in the two groups (56%, 64%, p=0.05). But, pre-operative therapy was seen more in the control group (77% vs. 51%, p=0.01). Regression model showed a protective effect for heparin if it was given pre-operatively (OR=0.37, p=0.047) with no effect if it was given beyond 10 hours. Mean blood transfusion units (97 and 106 mL) and hemorrhagic events (4.5% and 5%) were similar (p=NS). Median (range) length of hospital stay was longer (19 days (0-201) vs. 6 (0-66), p=0.001) and two-year survival lower in the TE group (p=0.03).

data from our institutional case-control study shows that heparin administration before GS is associated with more than 2-fold reduction in the risk of thromboembolism. The optimal period appears to be between 1–10 hours prior to the time of incision. Large prospective trials need to be desgined to more accurately determine the time of heparin therapy.

No relevant conflicts of interest to declare.