Role of thrombolestagrophy in monitoring perioperative coagulation status and effect of thromboprophylaxis in bariatric surgery

BACKGROUND

Thromboelastography is a technique that surveys the properties of viscoelastic blood clot. The purpose of this paper was to evaluate the hypercoagulability state and the effect of antithrombotic prophylaxis on thromboelastogram (TEG) results in bariatric surgery.

METHODS

Twenty-five patients enrolled received 0.8 ml of nodraparin starting on the day before surgery and continuing postoperatively. TEG profile was collected before induction of anesthesia, on the first and third postoperative days. Each sample was run also in a cup added with heparinase to eliminate the interference of antithrombotic prophylaxis.

RESULTS

TEG analysis with heparinase showed a tendency to reduce the r-time (rate of initial fibrin formation) and k-time (time to clot firmness) and increase the alpha angle (rate of clot growth), while an increase of maximal amplitude (MA, a measure of maximal stiffness of the clot; p = 0.01) and GI or shear elastic modules strength (p = 0.03)was observed from basal to postoperative day 3 (POD3). TEG without heparinase evidenced and increase of r-time (p = 0.02) and k-time (p = 0.05), a reduction of the alpha angle (p = 0.03), and an increase of MA (p = 0.01) and GI (p = 0.03) from basal to POD3. The comparison of TEG techniques showed that normal TEGs had lower values of r-time and k-time and higher values of alpha angles and MA than TEG with heparinase. No differences were evident for basal and POD1 samples and the G values comparing the two TEG technique. No correlation was observed between the variation of normal TEG parameters and dosage of anticoagulant used in each patient.

CONCLUSIONS

Our patients presented a tendency to hypercoagulability determined most by MA and GI. Comparison between TEGs indicates that low-molecular-weight heparin not titrated on weight is able to determine a reduction of hypercoabulable tendency in the early postoperative period with few effects on increasing MA and GI.

Resistance to glomerular injury in the diabetic biobreeding rat

This study was designed to determine whether the diabetic BioBreeding rat develops significant renal injury following long-term moderate to severe hyperglycaemia. Diabetic and control rats were followed from the onset of diabetes (2-4 months) to 18 months of age. Frank proteinuria and/or albuminuria were always absent. Glomerular filtration rate, measured by inulin clearance (ml min-1 (100 g body weight)-1), was significantly higher in diabetic rats than in controls at 10, 12 and 18 months of age. Advanced glycosylation end-product cross-links assessed by percentage solubility of tail tendon collagen were moderately increased in diabetic compared with control animals. Urinary excretion of advanced glycosylation end-products in unfractionated urine and in urine fractionated for low molecular mass peptides (< 10 kDa) was 11-fold greater in the diabetic rats than in the control group. Urinary excretion of nitric oxide metabolites (nmol NO2- and NO3- (24 h)-1) were significantly (P < 0.05) greater in diabetic rats than in controls after 8 months of age. Mild histopathology resembling human diabetic nephropathy, including increased mesangial volume and glomerular basement membrane thickness, was detected at 18 months of age. The findings of hyperfiltration and mild glomerular morphological changes in diabetic BioBreeding rats are similar to the abnormalities seen in stage 2 human diabetic nephropathy. We hypothesize that two factors which may contribute to the resistance or tolerance to renal injury in the BioBreeding diabetic rat are increased nitric oxide production and the decreased accumulation of advanced glycosylation end-products.