肝素治疗肺血栓栓塞症达标剂量与达标时间初步研究

目的:研究以13u·h-1·kg-1作为肝素起始剂量的肺血栓栓塞症(PTE)患者抗凝达标时间和有效维持剂量。方法:记录25例PTE患者治疗前及使用肝素后每6h一次的活化部分凝血酶原时间(APTT)和血浆肝素浓度值;计算在肝素起始剂量13U治疗下24h、48h及72h APTT达标率,至APTT稳定达标所需时间,所有患者每d肝素需求总量;运用相关性与单因素线性回归的统计学方法探讨血浆肝素浓度与APTT值的线性关系、肝素剂量与APTT值的线性关系,并推算其稳定达标时肝素维持量。结果:累积剂量平均法推算的所有患者单位时间内肝素维持量平均(12.43±2.58)u·h-1·kg-1,95%可信限区间为11.37～13.50u·h-1·kg-1;回归方程推导的肝素维持量是(11.52±2.71)u·h-1·kg-1与95%可信限区间是11.01～11.36u·h-1·kg-1。各种维持量中,实际维持量介于11～13u·h-1·kg-1的患者在24h与72h内所占比例分别为37%与32%;使用11～13u·h-1·kg-1维持剂量者首日达标率75%,次日为100%。所有患者在起始剂量13u·h-1·kg-1治疗并主要依据Raschke量表调整后24h、48h及72h累计APTT达标率分别是76%、96%和100%;所有患者达标时间中位数为18h,众数为12h。结论:本组PTE患者平均肝素维持剂量介于11～13u·h-1·kg-1;在肝素起始剂量13u·h-1·kg-1治疗下,所有患者24h累计APTT达标率为76%,达标时间中位数为18h。     

肝素个体剂量在肺栓塞治疗中的确立及影响因素

目的 :探讨肝素抗凝治疗肺血栓栓塞 (PTE)症时 ,尽快达到部分凝血活酶时间 (APTT)值在4 5～ 90s区间 (简称达标 )的个体维持剂量及影响因素。方法 :分析 4 2例接受肝素持续静脉点滴法抗凝治疗的PTE病人的临床资料 ;观察 72h内个体肝素用量及达标状况 ;比较达标组与未达标组 ,超标组肝素用量的差异及出血发生率 ;分析其影响因素。结果 :4 2例PTE患者中达标 31例 ,占 73 8%。达标者每人每日肝素平均剂量为 2 182 1u ,所用肝素维持量中位数为 12 9u·kg- 1 ·h- 1 。超标组出血副作用的发生率高于达标组 ,2组有显著性差异 (P <0 0 5 )。治疗反应值 (溶栓或负荷量肝素治疗后即刻APTT值与基础APTT的比值 )与肝素用量呈反比关系。结论 :肝素维持量个体差异大。达标组所需肝素量中位数低于国外推荐剂量 (18u·kg- 1 ·h- 1 )。发病危险因素及病程为其主要影响因素。无家族遗传倾向及恶性肿瘤疾病的急性肺栓塞患者若治疗反应值 >1 5 ,推荐首选肝素维持剂量为 13u·kg- 1 ·h- 1 。     

无负荷剂量右美托咪定镇静对老年危重病人血流动力学的影响

目的探讨危重病人无负荷剂量应用右美托咪定镇静效果及对血流动力学的影响。方法随机选取2013年1⁶月该院ICU收治的86例需要持续镇静的危重患者,APACHEⅡ评分(19±7)分,视患者临床情况给予舒芬太尼静脉持续泵入,使Prince-Henry疼痛评分≤3分。镇静方法采用无负荷剂量持续静脉输入右美托咪定,起始剂量0.4μg·kg-1·h-1,调整泵入剂量0.26月该院ICU收治的86例需要持续镇静的危重患者,APACHEⅡ评分(19±7)分,视患者临床情况给予舒芬太尼静脉持续泵入,使Prince-Henry疼痛评分≤3分。镇静方法采用无负荷剂量持续静脉输入右美托咪定,起始剂量0.4μg·kg-1·h-1,调整泵入剂量0.2⁰.7μg·kg-1·h-1,使RSS评分30.7μg·kg-1·h-1,使RSS评分3⁴分。结果 74例(86.1%)患者能获得良好的镇静效果。在静脉泵入右美托咪定的第1个小时内,有12%的病人平均收缩压(SBP)下降,14%的病人心率下降。突然停药后,24 h持续观察SBP升高5%,心率升高18%。结论对于危重病人来说,不用负荷剂量持续泵入右美托咪定可以维持良好的镇静效果,维持泵入期间患者的血压、心率下降是可以预测并能有效控制的,持续应用超过24 h后突然停药未见明显的血流动力学反跳。     

肝素治疗肺血栓栓塞症抗凝剂量浓度与活化部分凝血酶原时间关系初步探讨

目的:以13 U/(h.kg)作为肺栓塞患者肝素抗凝起始量,分别研究该起始量下肝素剂量及血浆肝素浓度与活化部分凝血酶原时间(APTT)的线性量化关系,利用线性方程预测维持量、达标浓度与APTT区间。方法:记录25例PTE患者治疗前及使用肝素后每6 h 1次的APTT和血浆肝素浓度值;运用相关性与单因素线性回归的统计学方法探讨血浆肝素浓度与APTT值的线性关系、肝素剂量与APTT值的线性关系。结果:1.肝素浓度与APTT的线性关系(均P<0.05)。2.肝素剂量与浓度的线性关系:所求个体内相关系数、决定系数与个体间相关系数、决定系数几乎均P>0.05,未能求出差异有统计学意义的单因素线性回归方程。3.肝素剂量与APTT的线性关系:回归方程为APTT=2.72×肝素剂量+35.265(P=0.003),肝素剂量=0.0144×APTT+10.356(P=0.003)。结论:1.肝素浓度(抗Ⅱ因子法)与APTT之间具有良好的正相关性与线性关系,提供了APTT代替肝素浓度检测的依据。2.肝素剂量、浓度与APTT的相互关系受多重因素影响,单因素线性相关与回归模型不足以正确揭示肝素剂量与浓度的关系。     

低剂量低分子肝素抗凝治疗自发性脑出血合并肺栓塞的安全性与疗效评价

目的:探讨自发性脑出血(SICH)合并肺栓塞(PE)患者应用低剂量低分子肝素抗凝治疗的有效性和安全性。方法:回顾性分析2011年1月至2016年12月,河南科技大学第一附属医院收治的SICH合并PE患者66例,根据治疗方案的不同分为对照组(A组:未给予抗凝治疗)、足量抗凝组(B组:低分子肝素钙100i U/kg,1次/12h)、低剂量抗凝组(C组:低分子肝素钙3 000i U,1次/12h/5 000i U,1次/d);评估影响脑SICH合并PE预后的因素;对比不同剂量抗凝治疗肺栓塞疗效、再出血发生率和30d内死亡率。结果:(1)不同剂量抗凝药物是影响SICH合并PE疾病预后的重要因素(P0.05);(2)足量抗凝组(B组)与低剂量抗凝组(C组)对比肺栓塞疗效评价好转率,差异无统计学意义(P0.05);C组再出血率和30d死亡率少于B组,差异有统计学意义(P0.05)。结论:应用低剂量低分子肝素治疗SICH合并中低危PE患者可能是一种有效、安全的方法。     

抗凝治疗急性肺栓塞的临床观察

目的：探讨抗凝治疗急性肺栓塞的剂量，有效率及安全性。方法：对62例急性肺栓塞患者给予普通肝素1000U／h，同时给予华法林2．5mg,1次／d，口服，肠溶阿斯匹林0．3，1次／d，口服，监测APTT及INR，使APTT目标值为正常对照值的1．5～2．5倍，INR保持在2．0～3．0左右。应用7天后停用普通肝素，华法林继续应用3～6个月，根据INR调整用量。经抗凝治疗4～6周后复查放射性核素肺灌注扫描。结果：显效43例，有效11例，无效8例，总有效率(显效 有效)87．1％(54／62)，无效率12．9％(8／62)。结论：急性肺栓塞患者抗凝治疗安全有效，经济。     

初始抗凝与溶栓治疗对老年急性中高危PTE患者血浆D-二聚体、cTnT、NT-proBNP、血气分析和超声心动图的影响

目的 探讨初始抗凝与溶栓治疗对老年急性中高危肺血栓栓塞症(PTE)患者血浆D-二聚体、肌钙蛋白(cTn)T、B型脑钠肽前体(NT-proBNP)、血气分析和超声心动图影响。方法 选择东阳市人民医院于2015年1月至2021年12月老年急性中高危PTE患者80例,依据随机表法分为溶栓组(40例)与抗凝组(40例)。溶栓组采用初始溶栓治疗;抗凝组采用初始抗凝治疗。两组接受标准剂量的初始溶栓或初始抗凝治疗后,每间隔4 h测定部分凝血活酶时间(APTT),当APTT低于基线值的1.5～2.0倍(或<80 s)时,开始皮下注射那曲肝素钙注射液(86 U/kg),每12 h 1次。两组疗程均为7 d。比较两组治疗疗效;治疗前后血浆D-二聚体、cTnT和NT-proBNP水平,血气分析和超声心动图变化及出血事件发生情况。结果 溶栓组总有效率(90.00%)显著高于抗凝组(70.00%;P<0.05)。两组治疗后血浆D-二聚体、cTnT和NT-proBNP水平显著低于治疗前(P<0.05);溶栓组治疗后血浆D-二聚体、cTnT和NT-proBNP水平显著低于抗凝组(P<0.05...     

冠状动脉介入治疗中不同肝素的抗凝效果比较

目的通过监测抗-Xa因子活性及活化凝血酶原时间(APTT)值评价低分子肝素(LMWH)联合普通肝素(UH)在冠状动脉介入(PCI)治疗中的安全性和有效性,探讨适合人群的PCI抗凝策略。方法入选50例急性冠脉综合征(ACS)病人,均给予1mg/kg的达肝素(法安明)每隔12h皮下注射1次,至少48h后行PCI,术前连续使用LMWH,末次给药距离造影不超过8h。对照组术中不加用UH,术后取血测定抗-Xa活性及APTT值,试验组行PCI前追加UH,术后测定抗-Xa活性及APTT值。结果对照组仅有69.5%病人的抗-Xa活性>0.5U/L,APTT值为(38.6±13.9)s,试验组80.2%的病人抗-Xa活性>1.2U/L,20%抗-Xa活性>1.5U/L,APTT值为(160.3±87.2)s。结论皮下注射达肝素48h后PCI术中追加普通肝素对ACS病人安全、有效,但应门诊随访。     

肝素在老年急性冠状动脉综合征患者介入治疗后的应用

摘要:目的探讨老年急性冠状动脉综合征(ACS)患者PCI术后如何应用普通肝素(UFH)抗凝。方法选择接受PCI的老年ACS患者100例。所有患者采用静脉UFH抗凝至少24 h,并随机分为试验组(50倒)和对照组(50例)。试验组按预先设定的UFH标准化抗凝方案调节剂量,对照组由值班医师凭经验调整剂量。以活化部分凝血活酶时间(APTT)45～75 s作为UFH抗凝治疗范围。结果试验组和对照组分别测量APTT 328次和351次,两组抗凝达标比例分别为80.2%和47.3%(P<0.01)。试验组达到治疗范围的平均时间明显小于对照组[(2.9±3.4)h vs (7.6±3.4)h,P<0.01];试验组24 h维持在治疗范围内的平均时间明显大于对照组[(16.9±3.5)h vs(11.6±4.1)h,P<0.01]。结论 UFH标准化抗凝方案可以安全有效地应用于老年ACS患者PCI术后抗凝。     

脑静脉血栓形成17例诊治体会

目的探讨脑静脉血栓形成的有效诊治方法。方法根据临床表现及颅脑影像学检查诊断脑静脉血栓形成患者17例,3例采用低分子肝素皮下注射溶栓,14例持续静脉泵入普通肝素,据APTT值调整普通肝素剂量,常规使用2~3周。肝素静脉泵入不能阻止病情进展者采取介入溶栓,肝素及介入溶栓后给予华法令口服抗凝治疗。结果 17例肝素治疗2~3周,14例脑静脉窦血栓再通,2例足量普通肝素静脉泵入效果不佳采取介入溶栓再通,1例合并血液病治疗效果不佳。随访半年,12例预后好,生活自理;3例留有残疾,不能行走及言语;1例死亡;1例失访。结论颅脑MRI联合MRV是诊断脑静脉血栓的可靠手段,应用肝素抗凝治疗脑静脉血栓安全有效。     

Improved anticoagulation with a weight-adjusted heparin nomogram in patients with acute coronary syndromes: A randomized trial

The optimal heparin dosing schedule to achieve rapid and therapeutic anticoagulation has not been established. The objective of this study is to determine whether an intravenous heparin dosing nomogram based on body weight achieves adequate anticoagulation more rapidly than a standard-care nomogram. Sixty-four patients requiring intravenous heparin treatment for acute coronary syndromes, but who did not receive thrombolytic therapy, were randomized to a standard-care nomogram in which heparin was given as a 5000 unit IV bolus followed by 1000 U/hr, or a weight adjusted nomogram in which heparin was given as an 80 U/ kg IV bolus and 18 U/kg/hr. Activated partial thromboplastin time (APTT) values were checked at 6,12,18, 24, and 48 hours and adjusted either by 100–200 U/hr (standard-care nomogram) or by 2–4 U/kg/hr (weight-based nomogram). Activated partial thromboplastin times were measured using a widely generalizable laboratory method. The primary goal was to achieve and maintain the APTT between 60 and 90 seconds. The median APTT values were higher in the weight adjusted group compared with the standard-care group at 6, 12, 18, 24, and 48 hours: 150 versus 83 (p=0.001), 100 versus 79 (p=0.09), 66 versus 61 (p=0.005), 63 versus 56 (p = 0.09), and 64 versus 56 (p=0.11). At 18 hours only 11% of patients in the weight-adjusted group had an APTT <61 compared with 26% in the standard-care nomogram (p=0.007). No major bleeding complications were noted in either group. A weight-adjusted heparin nomogram offers improved anticoagulation in the first 24 hours after heparin initiation compared with a standard-care nomogram in patients with acute coronary artery syndromes.     

A standard heparin nomogram for the management of heparin therapy.

A nomogram for the adjustment of heparin dosage was developed to standardize heparin therapy and to reduce delays in achieving and maintaining a therapeutic activated partial thromboplastin time (APTT) result. Fifty consecutive patients with acute venous thromboembolism had their continuous intravenous heparin therapy adjusted according to this heparin nomogram. The effect of the nomogram on heparin therapy in these patients was compared with data from 53 historical control patients. The proportion of patients in the nomogram group who reached a therapeutic APTT at 24 hours after the start of heparin therapy was 66%, which increased to 81% at 48 hours. In contrast, 37% and 58% of the control patients reached a therapeutic APTT at 24 and 48 hours, respectively. The percentage of therapeutic APTT results of the total number of APTT determinations was greater in the nomogram patients than controls. The use of this heparin nomogram resulted in (1) achieving a therapeutic APTT at 24 and 48 hours in a large proportion of patients and (2) reduced periods of inadequate anticoagulation and overanticoagulation during heparin therapy.     

The Effect of Body Weight and Body Surface Area Correction on the Distribution of the ACT Response to Bolus Doses of Heparin for PTCA

Considerable controversy exists as to the appropriate dosing of heparin for PTCA. We retrospectively reviewed records of 335 patients undergoing PTCA to determine: 1) the effects of correcting for weight and body surface area (BSA) on the heparin dose-response distribution; and 2) the average dose of heparin (standard, weight-based, and BSA-based) required to achieve an activated clotting time (ACT) of 300 seconds. For each patient, height, weight, BSA, baseline ACT (HemoTec), bolus heparin dose, and post-heparin ACT were recorded and the heparin response calculated. There were no significant differences in the distributions of standard (SD =.017 +/- 006 sec/U, 34% of mean), weight-based (SD = 1.41 +/- 0.46 sec/U/kg, 33% of mean), and BSA-based (SD = 0.033 +/- 0.011 sec/U/m2, 32% of mean) heparin response. There were slight, but significant correlations between heparin response and weight (r = 0.37) and heparin response and BSA (r = 0.36). The estimated doses of heparin to achieve a HemoTec ACT of 300 seconds were 10,650 +/- 1270 U, 130 +/- 15 U/kg, and 5390 +/- 640 U/m2. CONCLUSIONS: There are slight but significant correlations between heparin response and both weight and BSA. The distributions of weight- and BSA-corrected heparin response are similar to that of standard heparin dosing. Thus, weight adjusted heparin dosing would not appear to be likely to provide a more reliable ACT response to bolus doses of heparin.     

New method to predict patients’ intravenous heparin dose requirements

OBJECTIVE: To predict intravenous heparin dose requirements of patients treated for thromboembolic disorders. DESIGN: A retrospective cohort study in which we used simple linear regression to predict patients’ effective maintenance dose (EMD) of heparin (units/kg/hour needed to achieve and maintain APTT therapeutic range) from patients’ “heparin responsiveness” (the APTT increase after the initial 6 hours of heparin treatment per units/kg/hour received). SETTING/PATIENTS: The model was derived from 46 patients treated at one hospital (Hospital A) and then tested in 42 patients treated at another hospital (Hospital B). MEASUREMENTS AND MAIN RESULTS: Among Hospital A patients, there was a strong linear correlation (r=?.880;p <. 001) between EMD (mean 16.02 units/kg/hour; 95% CI 14.9, 17.15) and “heparin responsiveness” (HR): EMD=25.651 — [95.118×HR]. This model accurately predicted Hospital B patients’ EMD: 97% (37/38) fell within the model’s 95% prediction interval; the mean absolute difference between predicted and actual EMD was 1.73 units/kg/hour (95% CI 1.39, 2.08); and only 16% of patients had EMD’s more than 3 units/kg/hour different from that predicted by the regression model. The model’s accuracy was comparable to that of our gold standard, the weight-based heparin dosing nomogram. CONCLUSION: The infusion dose of intravenous heparin effective for an individual patient can be predicted accurately from the patient’s body weight and APTT response to the initial 6 hours of treatment. Especially in hospitals where validated heparin dosing nomograms are not used, clinicians may find this simple technique useful in achieving timely therapeutic anticoagulation.     

Heparin dosing and outcome in acute coronary syndromes: the GUSTO-IIb experience. Global Use of Strategies to Open Occluded Coronary Arteries

Background This study analyzed relationships among heparin dosage, patient characteristics, and 30-day outcome because optimal unfractionated-heparin dosing in acute coronary syndromes remains uncertain. Methods Patients (n = 5335) randomized to heparin therapy in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb trial were studied. The heparin dose was adjusted to a target activated partial thromboplastin time (aPTT) and normalized for the patient's weight. Mortality and cardiac (re)infarction within 30 days and their association with patient characteristics and heparin dosing were evaluated. Results The lowest mortality rate appeared with a heparin dose of approximately 14 U/kg/h or an aPTT of approximately 70 seconds. Heparin dosing was a significant predictor of outcome after adjusting for presenting coronary syndrome; a trend remained after adjusting for other baseline differences. This association was lost when adjusted for the aPTT result. Patients who died early appeared to have lower heparin dosing than those with later mortality (P = .012). Heparin “resistance” with relatively high heparin dosages and low aPTT values did not increase the risk for adverse outcome. Conclusions There is a defined, dose-associated benefit of unfractionated heparin in acute coronary syndromes similar to that seen previously in thrombolytic-treated infarctions. Heparin therapy is complicated by its complex biologic interactions and relatively crude measures of its effect. Better measures of heparin effectiveness and strategies need to be developed with either better antithrombin agents or adjunctive therapies such as antiplatelet regimens to treat patients who require benefits beyond that supplied by unfractionated heparin. (Am Heart J 2002;144:73-80.)     

Utility of a weight-based heparin nomogram for patients with acute coronary syndromes

Abstract
Background:  Unfractionated heparin has been pivotal in the management of acute coronary syndromes (ACS), and continues to be used widely despite the emerging role of low molecular weight heparins (LMWH). The apparent superiority of LMWH over unfractionated heparin may, at least partially, reside in its more predictable achievement of therapeutic effect, with high rates of non-therapeutic activated partial thromboplastin time (APTT) results being observed in the intravenous heparin treatment groups.
Aim:  To evaluate the impact of introduction of a weight-based heparin nomogram developed for use in patients with ACS on frequency of 'therapeutic' APTT results.
Methods:  The effectiveness of an existing non-weight-based heparin nomogram in achieving a therapeutic APTT was compared sequentially with that of a weight-based heparin nomogram in 89 and 84 consecutive patients admitted with a diagnosis of ACS.
Results:  Patients in whom heparin dosage adjustment was weight based rapidly achieved therapeutic APTT. The median time to achieve an APTT within the target range was 8.75 h in the weight-based group versus >24 h in the non-weight-based group. Utilization of a weight-based nomogram was associated with markedly increased proportions of readings within the therapeutic APTT range at 6 h and at 24 h (51% vs . 26% and 72% vs . 36%, respectively).
Conclusions:  The current study confirms the marked superiority of the weight-based heparin regimen for treatment of patients with ACS. The nomogram dramatically facilitated the attainment of therapeutic APTT, and may represent the optimal method for titration of heparin dosage to individual heparin requirements in patients with ACS. (Intern Med J 2003; 33: 18−25)     

Kinetics of intravenously administered heparin in normal humans

Heparin of five commercially available brands was used to study the disappearance of heparin anticoagulant activity in normal humans. The drug was administered intravenously by bolus injection and by continuous infusion. Heparin anticoagulant activity was determined by two assays: a diluted activated partial thromboplastin time (APTT) and an assay based on inactivation of bovine factor Xa, using a clotting system. After a bolus injection, the data fitted neither single exponential nor zero-order clearance. In semilogarithmic plots, heparin anticoagulant activity disappeared according to a slightly convex curve almost always preceded by a rapid initial loss of heparin anticoagulant activity. This disappearance profile was observed with all heparin regardless of the brand or assay system. Heparin anticoagulant activity estimated by the APTT disappeared faster than heparin anticoagulant activity estimated by the anti-Xa activity in the first phase. As expected, higher anticoagulant levels with the anti-Xa assay than with the APTT were also found on continuous infusion in normals as well as in patients treated for deep vein thrombosis or pulmonary embolism. The experimental data suggested a model based on the combination of a saturable and a linear clearance mechanism. These experimental data provide reliable guidelines for adjustment of the dose of heparin in single patients.     

Single bolus administration of recombinant tissue plasminogen activator: effects on infarct related vessel patency, microvascular perfusion, and microvascular reocclusion in a canine model of thrombotic occlusion/reperfusion

STUDY OBJECTIVE--The aim was to evaluate the thrombolytic efficacy of recombinant double chain tissue plasminogen activator (Duteplase, t-PA) given as a single intravenous bolus versus an infusion in a canine model of coronary arterial occlusion/reperfusion. DESIGN--Coronary arterial thrombi were induced by a copper coil (placed under fluoroscopic control) in the left anterior descending coronary artery of anaesthetised dogs. Following 90 min thrombotic occlusion, animals were randomly assigned to one of two treatment groups: group 1 = t-PA infused intravenously at 0.6 x 10(6) IU.kg-1.h-1, or group 2 = t-PA (0.6 x 10(6) IU.kg-1) by intravenous bolus over 6 min. Both groups received concurrent heparin (six 1000 IU boluses, + 100 IU.kg-1.h-1) throughout t-PA administration and the 2 h reperfusion period. SUBJECTS--16 beagle dogs of either sex were used, weight 9.2-20.3 kg. MEASUREMENTS AND MAIN RESULTS--Radiolabelled microspheres were injected to assess microvascular coronary flow at various time points throughout the experimental period. Infarct related vessel patency (IRVP) was assessed arteriographically every 5 min. Infarct size was assessed histochemically at the end of the reperfusion period. IRVP was achieved within 42.9 (SEM 7.4) min and 43.1(7.0) min for infusion and bolus groups respectively; 60 min patency rates were 88% for both groups. t-PA restored full microvascular flow to ischaemic subendocardial and subepicardial regions in both groups compared to initial preocclusion regional blood flow. Extent of reactive hyperaemia was greater in infusion than bolus treatment animals: infusion group 1.18(0.15) v bolus group 0.72(0.14) ml.min-1.g-1 (subepicardial). Degree of microvascular reocclusion at 120 min reperfusion was similar for both groups despite aggressive anticoagulation throughout: infusion group 0.33(0.08) v bolus group 0.42(0.11) ml.min-1.g-1 (subendocardial). Areas of the myocardium at risk (R), absolute infarct size (I), and infarct risk ratio (I/R) were similar for both groups: R = 33.9(1.5) v 30.9(1.9)%; I = 15.9(3.1) v 13.3(3.1)%; I/R = 46.3(8.4) 42.1(9.2)%. Degree of systemic fibrinogenolysis was similar for both groups: infusion 1.65(0.40) to 0.67(0.07) g.litre-1 v bolus 1.68(0.15) to 0.96(0.12) g.litre-1. CONCLUSIONS--Single bolus administration of t-PA showed equivalent efficacy to infusion dosing in respect of IRVP, microvascular reperfusion, and microvascular reocclusion. As a result the degree of tissue necrosis (I/R ratio) was no different when comparing the two dosing regimens. Similar degrees of systemic fibrinogenolysis were observed for both treatment groups.     

Chemical prophylaxis to prevent venous thromboembolism in morbid obesity: literature review and dosing recommendations

Pharmacologic prophylaxis of deep vein thrombosis and venous thromboembolism (VTE) is an important aspect of medical care, particularly in the inpatient setting. Low-molecular weight heparins, heparin, and fondaparinux are commonly used agents to prevent VTE, each of which has well established dosing regimens in patients with normal body mass index. Dosing of these medications in morbidly obese populations (BMI > 40 kg/m²) is not as clearly defined in guidelines. This article reviews published data to support specific dosing regimens and monitoring strategies of these agents in this population. The most validated parenteral agent to prevent VTE in morbidly obese hospitalized patients is enoxaparin, dosed at 40 mg subcutaneously (SC) twice daily. If unfractionated heparin is utilized for prophylaxis in morbidly obese patients, a dose of 7500 units SC three times daily should be considered. Monitoring of anti-factor Xa levels to guide prophylactic dosing is an option, although the utility of this lab test is limited, as target anti-Xa ranges for VTE prophylaxis have not been universally defined and trials have not shown a clear link between anti-factor Xa levels and bleeding or thrombotic events. Additional studies are needed to clearly define the most appropriate dosing strategies in patients with moderate obesity (BMI 35–40 mg/m²) and those with extreme obesity (BMI > 60 mg/m²).