Anticoagulant Effect of Standard Dose Heparin During Peripheral Endovascular Intervention.

BACKGROUND: The objective of this clinical study was to investigate the anticoagulant effect of standard fixed dose of heparin during endovascular intervention in the lower extremity arteries. METHODS: A prospective clinical pilot study was completed with retrospective quality review of patients between 2015 and 2017 (n = 61). Patients undergoing elective endovascular intervention for arterial insufficiency in the lower extremities were enrolled. A standard fixed intra-arterial dose of 5000 IU of unfractionated heparin (UFH) was administered during the procedure without adjustment for weight or monitoring. Activated clotting time (ACT) was measured before and ten minutes after heparin administration and at the end of the procedure. The primary study end point was the level of heparin anticoagulation after standard perioperative administration. RESULTS: Mean age was 74 ± 9 years, 48% women. Mean weight was 74 ± 15 kg, and mean BMI, 25.6 ± 4.7 kg/m2. The endovascular interventions were performed at the iliac arteries 19.7% (12/61), at the femoral popliteal segment 50.8 % (31/61), below the knee arteries 6.6% (4/61), and at multiple levels 13% (8/61). The perioperative mean ACT increased from baseline 155 ± 43 s (n = 31) to ten minutes after heparin administration 290 ± 70 s (n = 60) (P < 0.01) and was at the end of the procedure 276 ± 73 s (n = 59). Perioperative ACT ten minutes after heparin administration: 5.0% (3/60) of the patients had ACT <200 s, 25.0% (15/60) had ACT 200-250 s, 48.3% (29/60) ACT 251-349, and 21.7% (13/60) ACT ≥350 s. At the end of the procedure, 17.2 % (10/58) of the patients had ACT <200, 24.1 % (14/58) had ACT 200-250 s, 37.9% (22/58) ACT 251-349, and 20.7 % (12/58) ACT ≥350 s. The mean dose of heparin per kg body weight was 70 ± 15 IU/kg. There was a significant difference between the ACT groups when analyzing heparin dose per kg body weight: 54 ± 14 IU/kg for patients with ACT <200, 69 ± 13 IU/kg with ACT 200-250 s, 68 ± 13 IU/kg with ACT 251-349, and 81 ± 18 IU/kg with ACT >350 (P = 0.0095). The same pattern was seen for heparin dose per BMI and DuBois. In univariate logistic regression analysis, ACT ≥350 s was associated with lower body weight (OR 0.92; 95% CI 0.87-0.98; P = 0.008), lower BMI (OR 0.80; 95% CI 0.67-0.96; P = 0.014), and lower body surface area DuBois (OR 0.53; 95% 0.32-0.85; P = 0.009). In multivariable regression, the ACT association with body weight remained (OR 0.92; 95% 0.87-0.98; P = 0.008). There were no perioperative or immediate postoperative bleeding complications requiring blood transfusion or surgical intervention in this study cohort. CONCLUSIONS: The standard heparin dosing of 5000 IU during endovascular intervention for arterial insufficiency in the lower extremities helps achieve ACT >200 s in almost all patients, but most patients were outside recommended target interval. To provide a more consistent and predictable heparinization, a weight-based bolus dose of 70 IU heparin/kg is recommended.

An Adjusted Calculation Model Allows for Reduced Protamine Doses without Increasing Blood Loss in Cardiac Surgery.

Background Heparin dosage for anticoagulation during cardiopulmonary bypass (CPB) is commonly calculated based on the patient's body weight. The protamine-heparin ratio used for heparin reversal varies widely among institutions (0.7-1.3 mg protamine/100 IU heparin). Excess protamine may impair coagulation. With an empirically developed algorithm, the HeProCalc program, heparin, and protamine doses are calculated during the procedure. The primary aim was to investigate whether HeProCalc-based dosage of heparin could reduce protamine use compared with traditional dosages. The secondary aim was to investigate whether HeProCalc-based dosage of protamine affected postoperative bleeding. Patients and Methods We consecutively randomized 40 patients into two groups. In the control group, traditional heparin and protamine doses, based on body weight alone, were given. In the treatment group, the HeProCalc program was used, which calculated the initial heparin bolus dose from weight, height, and baseline activated clotting time and the protamine dose at termination of CPB. Results We analyzed the results from 37 patients, after exclusion of three patients. Equal doses of heparin were given in both groups, whereas significantly lower mean doses of protamine were given in the treatment group versus control group (211 ± 56 vs. 330 ± 61 mg, p < 0.001). Postoperative bleeding was less in the HeProCalc group (280 ± 229 mL) as compared with the control group (649 ± 279 mL). However, this difference was not found statistically significant (p = 0.074). Conclusion HeProCalc-based dosage of heparin and protamine allowed for reduced protamine use after CPB compared with when conventional calculations were used. Furthermore, HeProCalc-based regimen for heparin reversal suggested less postoperative bleeding, although the difference between the groups was not statistically significant.

Measuring elevated intracranial pressure through noninvasive methods: a review of the literature.

Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable. This article is a review of the current literature on noninvasive methods for measuring and evaluating elevated ICP. The main focus is on studies that compare noninvasively measured ICP with invasively measured ICP. The aim is to provide an overview of the current state of the most common noninvasive techniques available. Several methods for noninvasive measuring of elevated ICP have been proposed: radiologic methods including computed tomography and magnetic resonance imaging, transcranial Doppler, electroencephalography power spectrum analysis, and the audiological and ophthalmological techniques. The noninvasive methods have many advantages, but remain less accurate compared with the invasive techniques. None of the noninvasive techniques available today are suitable for continuous monitoring, and they cannot be used as a substitute for invasive monitoring. They can, however, provide a reliable measurement of the ICP and be useful as screening methods in select patients, especially when invasive monitoring is contraindicated or unavailable.