Prevention of venous thromboembolism in obesity

Comparison of enoxaparin 40 mg versus 60 mg dosage for venous thromboprophylaxis in patients undergoing bariatric surgery: A randomized controlled trial

BACKGROUND

Venous thromboembolism (VTE) is a common cause of morbidity and mortality after bariatric surgery. Morbid obesity is an independent risk factor for VTE, with goals of prophylactic anti-factor Xa levels within 0.2-0.5 IU/mL. The recommended dosing regimen of enoxaparin for VTE prophylaxis in patients with morbid obesity is lacking in available guidelines.

OBJECTIVES

To evaluate the achieving prophylactic anti-factor Xa levels with different dosages of enoxaparin for morbid obesity patients.

SETTING

We conducted a study at Chulalongkorn Bariatric and Metabolic Institute, King Chulalongkorn Memorial Hospital.

METHODS

We conducted a randomized controlled trial comparing anti-factor Xa levels 4 h after the administration of enoxaparin. All recruited patients randomly received 40 mg or 60 mg of enoxaparin 12 h before the operation. Blood specimens were collected 4 h after the administration of enoxaparin.

RESULTS

In total, 56 patients who presented between April 2019 and March 2020 at King Chulalongkorn Memorial Hospital were recruited. Of these patients, 28 received 40 mg and 28 received 60 mg of enoxaparin. In both groups, the rates of achieving target levels were 53.57% and 78.57%, respectively (p-value = 0.048). The mean anti-factor Xa levels were 0.19 IU/mL ± 0.06 IU/mL and 0.28 and 0.28 ± 0.10 IU/mL, respectively (p < 0.001). No significant difference was found in the estimated blood loss between the groups. No patient obtained anti-factor Xa levels exceeding 0.5 IU/mL. In both groups, no symptomatic VTE occurred.

CONCLUSIONS

A 60 mg of enoxaparin regimen achieved more prophylactic anti-factor Xa levels than 40 mg in obese patients undergoing bariatric surgery without any adverse events.

Monitoring anti-Xa levels in elderly medical patients undergoing thromboprophylaxis: A prospective cohort study

INTRODUCTION

Given the rising incidence of venous thromboembolism (VTE) and insufficient thromboprophylaxis dosing evidence in certain patients, the precise monitoring of anti-Xa (aFXa) levels is crucial. The aim of this study is to investigate the achievement of prophylactic aFXa levels in medical inpatients who were receiving parenteral anticoagulant and to evaluate the impact of various factors on aFXa levels.

METHODS

This is a single-center observational cohort study conducted on patients admitted to the Department of Internal Medicine at the University Hospital of Heraklion, Greece, from March to August 2023. These individuals received low-molecular-weight heparins thromboprophylaxis owing to an increased risk of VTE. Data regarding demographics, past medical history, and somatometric and laboratory findings were recorded. The established range for peak prophylactic aFXa levels was defined as 0.2-0.5 IU/mL.

RESULTS

In this study, we enrolled 150 individuals [91 (60.7%) women] with a mean age of 80.0 ± 14.1 years. Sixty-two (41.4%) patients exhibited non-prophylactic peak aFXa levels. Supratherapeutic levels were observed in all underweight patients and subtherapeutic levels in 12 of 13 obese patients in class II and III. A multivariate linear regression analysis revealed that body weight, cancer, and the Charlson Comorbidity Index (CCI) were independent factors influencing aFXa levels.

CONCLUSIONS

Our study reveals a substantial portion of medical elderly inpatients on thromboprophylaxis with non-prophylactic aFXa levels, with a notable prevalence among underweight and severely obese patients. Body weight, cancer, and CCI were identified as independent factors influencing aFXa levels, advocating for tailored thromboprophylaxis strategies. Further research is warranted to validate personalized dosing approaches and to enhance clinical decision-making. Geriatr Gerontol Int 2024; 24: 587-594.

Outcomes of heparin-induced thrombocytopenia type II in aneurysmal subarachnoid hemorrhage patients: A US nationwide analysis

BACKGROUND

Despite the widespread use of heparin during and following endovascular procedures in the management of aneurysmal subarachnoid hemorrhage (SAH) patients, limited research has explored the incidence and impact of heparin-induced thrombocytopenia (HIT) on SAH.

METHODS

Descriptive statistics, multivariate regressions, and propensity score-matching were employed to compare clinical characteristics, comorbidities, interventions, complications, and outcomes of HIT in SAH patients identified within the US National Inpatient Sample database from 2010 to 2019.

RESULTS

Among 76 387 SAH patients from 2010 to 2019, 166 (0.22%) developed HIT. HIT was identified as a significant predictor of prolonged length of stay (OR 6.799, 95% CI 3.985 to 11.6, P<0.01) and poor functional outcomes (OR 2.541, 95% CI 1.628 to 3.966, P<0.01) after adjusting for relevant factors. HIT incidence was higher in patients with elevated SAH severity scores (1.42 vs 1.06, P<0.01), younger patients (58.04 vs 61.39 years, P=0.01), overweight individuals (0.4% vs 0.2%, P<0.01), those on long-term anticoagulants (10.84% vs 5.72%, P<0.01), or with a cerebrospinal fluid drainage device (external ventricular drain, ventriculoperitoneal shunt; P<0.01). HIT patients showed increased rates of endovascular coiling, ventricular drain placement, shunt placement, deep vein thrombosis, urinary tract infection, acute kidney injury, pulmonary embolism, venous sinus thrombosis, pneumonia, and cerebral vasospasm (all P<0.01).

CONCLUSION

SAH patients with HIT exhibited various comorbidities and increased rates of complications, which may contribute to extended hospital stays. This nationwide study aids clinical suspicion and highlights HIT's impact on SAH patients.

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Portomesenteric Vein Thrombosis in Patients Undergoing Sleeve Gastrectomy: an Updated Systematic Review and Meta-Analysis of 101,914 Patients

INTRODUCTION

Portomesenteric vein thrombosis (PMVT) is a rare but potentially fatal complication of sleeve gastrectomy (SG). The rising prevalence of SG has led to a surge in the occurrence of PMVT, while the associated risk factors have not been fully elucidated. This study aims to determine the incidence and risk factors of PMVT in patients undergoing SG.

METHODS

A comprehensive literature search was performed in PubMed and EMBASE databases. Proportion and regression meta-analyses were conducted.

RESULTS

In a total of 76 studies including 101,914 patients undergoing SG, we identified 357 patients with PMVT. Mean follow-up was 14.4 (SD: 16.3) months. The incidence of PMVT was found to be 0.50% (95%CI: 0.40-0.61%). The majority of the population presented with abdominal pain (91.8%) at an average of 22.4 days postoperatively and PMVT was mainly diagnosed with computed tomography (CT) (96.0%). Hematologic abnormalities predisposing to thrombophilia were identified in 34.9% of the population. Advanced age (p=0.02) and low center volume (p <0.0001) were significantly associated with PMVT, while gender, BMI, hematologic abnormality, prior history of deep vein thrombosis or pulmonary embolism, type of prophylactic anticoagulation, and duration of prophylactic anticoagulation were not associated with the incidence of PMVT in meta-regression analyses. Treatment included therapeutic anticoagulation in 93.4% and the mortality rate was 4/357 (1.1%).

CONCLUSION

PMVT is a rare complication of sleeve gastrectomy with an incidence rate <1% that is associated with low center volume and advanced age but is not affected by the duration or type of thromboprophylaxis administered postoperatively.

Effectiveness, safety, and costs of thromboprophylaxis with enoxaparin or unfractionated heparin in inpatients with obesity

Background

Obesity is a frequent and significant risk factor for venous thromboembolism (VTE) among hospitalized adults. Pharmacologic thromboprophylaxis can help prevent VTE, but real-world effectiveness, safety, and costs among inpatients with obesity are unknown.

Objective

This study aims to compare clinical and economic outcomes among adult medical inpatients with obesity who received thromboprophylaxis with enoxaparin or unfractionated heparin (UFH).

Methods

A retrospective cohort study was performed using the PINC AI™ Healthcare Database, which covers more than 850 hospitals in the United States. Patients included were ≥18 years old, had a primary or secondary discharge diagnosis of obesity [International Classification of Diseases (ICD)-9 diagnosis codes 278.01, 278.02, and 278.03; ICD-10 diagnosis codes E66.0x, E66.1, E66.2, E66.8, and E66.9], received ≥1 thromboprophylactic dose of enoxaparin (≤40 mg/day) or UFH (≤15,000 IU/day) during the index hospitalization, stayed ≥6 days in the hospital, and were discharged between 01 January 2010, and 30 September 2016. We excluded surgical patients, patients with pre-existing VTE, and those who received higher (treatment-level) doses or multiple types of anticoagulants. Multivariable regression models were constructed to compare enoxaparin with UFH based on the incidence of VTE, pulmonary embolism (PE)---------related mortality, overall in-hospital mortality, major bleeding, treatment costs, and total hospitalization costs during the index hospitalization and the 90 days after index discharge (readmission period).

Results

Among 67,193 inpatients who met the selection criteria, 44,367 (66%) and 22,826 (34%) received enoxaparin and UFH, respectively, during their index hospitalization. Demographic, visit-related, clinical, and hospital characteristics differed significantly between groups. Enoxaparin during index hospitalization was associated with 29%, 73%, 30%, and 39% decreases in the adjusted odds of VTE, PE-related mortality, in-hospital mortality, and major bleeding, respectively, compared with UFH (all p < 0.002). Compared with UFH, enoxaparin was associated with significantly lower total hospitalization costs during the index hospitalization and readmission periods.

Conclusions

Among adult inpatients with obesity, primary thromboprophylaxis with enoxaparin compared with UFH was associated with significantly lower risks of in-hospital VTE, major bleeding, PE-related mortality, overall in-hospital mortality, and hospitalization costs.

Enhanced Recovery After Surgery Protocol in Bariatric Surgery Leads to Decreased Complications and Shorter Length of Stay

PURPOSE

Enhanced recovery after surgery (ERAS) programs have been shown in some specialties to improve short-term outcomes following surgical procedures. There is no consensus regarding the optimal perioperative care for bariatric surgical patients. The purpose of this study was to develop a bariatric ERAS protocol and determine whether it improved outcomes following surgery.

MATERIALS AND METHODS

An IRB-approved prospectively maintained database was retrospectively reviewed for all patients undergoing bariatric surgery from October 2018 to January 2020. Propensity matching was used to compare post-ERAS implementation patients to pre-ERAS implementation.

RESULTS

There were 319 patients (87 ERAS, 232 pre-ERAS) who underwent bariatric operations between October 2018 and January 2020. Seventy-nine patients were kept on the ERAS protocol whereas 8 deviated. Patients who deviated from the ERAS protocol had a longer length of stay when compared to patients who completed the protocol. The use of any ERAS protocol (completed or deviated) reduced the odds of complications by 54% and decreased length of stay by 15%. Furthermore, patients who completed the ERAS protocol had an 83% reduction in odds of complications and 31% decrease in length of stay. Similar trends were observed in the matched cohort with 74% reduction in odds of complications and 26% reduction in length of stay when ERAS was used.

CONCLUSIONS

ERAS protocol decreases complications and reduces length of stay in bariatric patients.

A Practical Approach to Total Laparoscopic Hysterectomy in a Morbidly Obese Patient: A Case Report and Literature Review

Morbid obesity, traditionally considered to be a contraindication to total laparoscopic hysterectomy, is now evolving into an indication. Innovations and advancements in minimally invasive surgical techniques have significantly improved patient morbidity and mortality rates, reduced operational costs, and provided patients with an overall safer surgical experience. Although the laparoscopic approach is associated with several physiologic and technical challenges in the morbidly obese, it is plausible that these patients stand to benefit the most from minimally invasive surgery. This report highlights the methods of preoperative optimization, intraoperative considerations, and postoperative management strategies employed to achieve a successful total laparoscopic hysterectomy, bilateral salpingo-oophorectomy and pelvic lymph node dissection in a patient with a BMI of 45kg/m², diagnosed with grade 1 endometrial adenocarcinoma and several obesity-related comorbidities.

Operative Techniques to Reduce Hip and Knee Arthroplasty Complications in Morbidly Obese Patients

Obesity, defined as a body mass index (BMI) >30, is associated with an increased likelihood of osteoarthritis and need for total joint arthroplasty (TJA). Unfortunately, the morbidly obese population has a higher risk of postoperative complications. For some surgeons, patient selection criteria for TJA includes BMI<40. The associated risks are recognized by The American Association of Hip And Knee Surgeons, and many surgeons follow these guidelines. Importantly, as obese patients have been demonstrated to have equal or greater gains in functional outcomes and quality of life metrics, it is important for obese patients to have access to TJA. Through a comprehensive literature review and structured interviews with leading surgeons in the field, we provide guidance for orthopedic surgeons treating patients with BMI>40 to minimize risks, including tailored preoperative, intraoperative, and postoperative considerations.

Improving compliance with venous thromboembolism prophylaxis guidelines in obese inpatients

Obesity is a well-recognised risk factor for venous thromboembolism, and increased dosing of pharmacological prophylaxis is recommended in obese inpatients. We performed a clinical decision support intervention by adjusting order sentences of prophylactic enoxaparin within our electronic medical records, which significantly improved appropriate dosing for thromboprophylaxis in obese inpatients at our institution.

Complications Associated with Administration of Post-operative Weight-Based Enoxaparin in Orthopaedic Trauma Patients

Background

In orthopedic-specific patients, limited evidence exists in regard to prophylactic weight-based enoxaparin dosing in the obese population. We examined the clinical outcomes of administering weight-based enoxaparin to obese orthopedic trauma patients.

Methods

This retrospective study involved 679 patients who underwent orthopedic trauma surgery and were admitted from 1/2016 to 6/2020 at a single institution. Of those patients, 156 patients met our inclusion criteria. Inclusion criteria included BMI>35 kg/m² and received weight-based enoxaparin post-operatively (defined as any singular dose >40 mg at any time). Blood transfusion, documented hematoma, deep vein thrombosis (DVT), and return visits to the OR after the administration of weight-based enoxaparin were the primary endpoints assessed. Age, BMI, weight, injury severity score (ISS), sex, post-operative time to the first dose of enoxaparin, the total daily dose of enoxaparin, operating room (OR) blood loss, OR time, patient co-morbidities, and pre/post-operative hemoglobin were evaluated for a potential relationship with the primary endpoints.

Results

One hundred and eighty-five surgeries were performed on a total of 156 patients. Thirty-six of the 185 (19%) surgeries required post-operative blood transfusion after weight-based enoxaparin was given. Higher ISS score, lower pre-operative hemoglobin, and lower post-operative hemoglobin were significant predictors of blood transfusion. Only increased post-operative time to the first dose of enoxaparin was significantly associated with DVT formation. Thirteen of the 156 patients (8.3%) had a post-operative hematoma after administration of enoxaparin, and four of the 13 patients required return to the OR for bleeding complications. ISS was the only significant predictor of post-operative hematoma formation.

Conclusion

Patients with a higher injury severity score are at an increased risk of adverse bleeding and may benefit from lower doses of enoxaparin administered earlier post-operatively.

Direct Oral Anticoagulants in the Treatment of Venous Thromboembolism: Use in Patients with Advanced Renal Impairment, Obesity, or Other Weight-Related Special Populations

There are currently more than 7 million patients taking a direct oral anticoagulant (DOAC), with more new prescriptions per year than warfarin. Despite impressive efficacy and safety data for the treatment of venous thromboembolism, patients with obesity or advanced renal impairment represented a small portion of the patients enrolled in the phase 3 clinical trials. Therefore, to evaluate the potential use of DOACs in these special populations, clinicians need to have an understanding of the pharmacokinetics and pharmacodynamics of these agents in these settings. Since data from randomized controlled trials are limited, data from observational trials are helpful in gaining comfort with the use of DOACs in these special populations. Selecting the appropriate dose for each agent is imperative in achieving optimal patient outcomes. We provide an extensive review of the pharmacokinetics, pharmacodynamics, phase 3 clinical trials, and observational studies on the use of DOACs in patients with advanced renal impairment, obesity, or other weight-related special populations to provide clinicians with a comprehensive understanding of the data for optimal drug and dose selection.

Healthcare resource utilization and costs of rivaroxaban versus warfarin among non-valvular atrial fibrillation (NVAF) patients with obesity in a US population

AIM

To assess the real-world healthcare resource utilization (HRU) and costs of patients with non-valvular atrial fibrillation (NVAF) and obesity newly initiated on rivaroxaban or warfarin in the US.

METHODS

This retrospective study used IQVIA PharMetrics Plus data (01/2010-09/2019) to evaluate patients (≥18 years) with NVAF and obesity (body mass index ≥30 kg/m²) initiated on rivaroxaban or warfarin (on or after 01/2013). Inverse probability of treatment weighting (IPTW) was used to adjust for confounding between cohorts. HRU and costs were assessed post-treatment initiation. Weighted cohorts were compared using Poisson regression models and cost differences, with 95% confidence intervals (CIs) and p values generated using non-parametric bootstrap procedures.

RESULTS

After IPTW, 10,555 and 5,080 patients were initiated on rivaroxaban and warfarin, respectively (mean age: 59 years). At 12 months follow-up, the rivaroxaban cohort had lower all-cause HRU, including fewer hospitalizations (rate ratio [RR]: 0.80, 95% CI: 0.74, 0.87), emergency room visits (RR: 0.89, 95% CI: 0.83, 0.97), and outpatient visits (RR: 0.72, 95% CI: 0.69, 0.77; all p < .05). Medical costs were also reduced in the rivaroxaban cohort (mean difference: -$6,759, 95% CI: -$9,814, -$3,311) due to reduced hospitalization costs (mean difference: -$5,967, 95% CI: -$8,721, -$3,327), resulting in lower total all-cause healthcare costs compared to the warfarin cohort (mean difference: -$4,579, 95% CI: -$7,609, -$1,052; all p < .05). The rivaroxaban cohort also had lower NVAF-related HRU and medical costs driven by lower hospitalization at 12 months post-treatment initiation. HRU and cost reductions associated with rivaroxaban persisted up to 36 months of follow-up.

LIMITATIONS

Claims data may have contained inaccuracies and obesity was classified based on ICD diagnosis codes given that patient BMI values were not available.

CONCLUSIONS

Rivaroxaban was associated with reduced HRU and costs compared to warfarin among NVAF patients with obesity in a real-world US setting.

Prophylactic Enoxaparin Dosing in Obese Orthopedic Patients: A Literature Search

Objective: The objective of the study was to review the current literature for prophylactic enoxaparin dosing in obese orthopedic patients. Method: A literature search was undertaken using OVID Medline, OVID Embase, and Cochrane Central databases, accessed through hospital library websites. Key search terms (in UK and US spelling) included orthopaedics, low-molecular-weight heparin, enoxaparin, venous thromboembolism prophylaxis, weight, obese, morbid obesity. Possible related subheadings, such as bone, fractures, anticoagulants, overweight, body mass index, deep vein thrombosis, pulmonary embolism, were also included in the database search to optimize the search strategies. The search was restricted to human subjects and limited to articles published from 1998 to the present. Results: The search identified 429 potentially relevant articles. Once duplicates were removed, 345 were screened for inclusion in this review. Only 3 articles (a case-control study, an observational prospective study, and a case report) met both the inclusion and exclusion criteria. The findings from this review need to be interpreted cautiously due to limitations in study designs and the potential for confounding bias. Conclusion: The results of a multiple database search draw one to the conclusion that there is very limited evidence in the literature with regard to prophylactic enoxaparin dosing in obese orthopedic-specific patients. Orthopedic patients are among the highest risk of all surgical specialties for venous thromboembolism. There is strong evidence to support an increased prophylactic low-molecular-weight heparin doses in obese patients; thus, the authors recommend higher prophylactic enoxaparin dosing in obese orthopedic patients.

Safety of High-Dose Unfractionated Heparin for Prophylaxis of Venous Thromboembolism in Hospitalized Obese Patients

BACKGROUND

Optimal dosing of unfractionated heparin (UFH) for thromboprophylaxis in the obese patient population is uncertain because of their high-risk, prothrombotic state and a complexity of pharmacokinetic considerations. Literature on the appropriateness of the use of a higher dose UFH regimen remains unclear and inconsistent.

OBJECTIVE

To evaluate the safety of the use of 7500 units every 8 hours (high-dose) of subcutaneous UFH compared with the use of 5000 units every 8 hours (standard-dose) of subcutaneous UFH for thromboprophylaxis in obese patients (defined as BMI ≥30 kg/m²).

METHODS

In a retrospective cohort study, 326 adult patients were included, with a BMI ≥30 kg/m², who were admitted to a large, urban academic medical center between September 1, 2015, and September 1, 2018. Patients received either high-dose or standard-dose UFH for at least 48 hours. The primary end point was the incidence rate of bleeding events, defined as a ≥2-g/dL fall in hemoglobin level or receipt of transfusion of 2 or more units of packed red blood cells (pRBCs) from the start of the UFH order.

RESULTS

The incidence rate of bleeding was significantly higher in those who received high-dose UFH (43%) compared with those who received standard-dose UFH (29%; P = 0.008). No significant difference was found between venous thromboembolism event rates.

CONCLUSION AND RELEVANCE

High-dose UFH was associated with an increased bleeding event rate compared with standard-dose UFH in patients with a BMI ≥30 kg/m². This raises safety concerns about the appropriateness of utilizing this regimen in this population.

Type 2 Diabetes Is a Risk Factor for Suffering and for in-Hospital Mortality with Pulmonary Embolism. A Population-Based Study in Spain (2016-2018)

(1) Background: The relationship between type 2 diabetes (T2DM) and pulmonary embolism (PE) has not been well stablished so far. We aim to analyze incidence, clinical conditions and in-hospital mortality (IHM) according to the presence of T2DM among patients hospitalized for suffering from PE. The factors associated with IHM were identified. (2) Methods: Patients aged ≥40 years hospitalized for PE from 2016 to 2018 included in the Spanish National Health System Hospital Discharge Database were analyzed. Dependent variables included incidence, IHM and length of hospital stay. Independent variables were age, sex, diagnosed comorbidities, thrombolytic therapy and inferior vena cava filter placement. Poisson and logistic regression models were constructed for multivariable analysis. (3) Results: Of the 47,190 hospitalizations for PE recorded, 16.52% had T2DM. Adjusted incidence of PE was higher among T2DM women (IRR 1.83; 95% CI: 1.58-1.96) and men (IRR 1.22; 95% CI: 1.18-1.27) than among non-diabetic subjects. Crude IHM in T2DM patients with PE was similar in both sexes but higher than in non-diabetic patients. Among T2DM patients with PE, risk factors for IHM included older age, comorbidity, atrial fibrillation and massive PE. Obesity was associated with lower IHM. Suffering T2DM was a risk of IHM (OR 1.15; 95% CI 1.05-1.26) after PE. (4) Conclusions: The incidence of PE is higher in T2DM men and women than in non-diabetic patients. T2DM was a risk factor for IHM after PE.

Description of anti-Xa monitoring practices during low molecular weight heparin use

Certain patient populations (pregnancy, cancer, renal impairment, and obesity) may be at higher risk of adverse events during low molecular weight heparin (LMWH) therapy and may benefit from anti-Xa monitoring. Yet, evidence supporting a standardized approach to anti-Xa monitoring correlated to clinical outcomes is lacking. Patients with at least one documented anti-Xa level and receiving LMWH within a 6-month period were identified. In a 6-month period, 224 adult LMWH patients with 359 anti-Xa levels were identified. Anti-Xa monitoring was most commonly performed in patients with active cancer receiving venous thromboembolism (VTE) treatment doses (57.4%) or obese patients receiving VTE prophylaxis (48.1%). Anti-Xa monitoring during renal impairment and pregnancy were infrequent (0.9% and 1.8%, respectively). Most (71.9%) anti-Xa levels were therapeutic, but only 45% were drawn correctly in relation to LMWH administration time. Compared to those with therapeutic anti-Xa levels, patients with out-of-range levels were four times as likely to receive a LMWH therapy change (odds ratio, 4.16; 95% confidence interval, 2.53-6.84). However, when levels were supratherapeutic or subtherapeutic, the LMWH doses remained unchanged in one-third to one-half of patients, respectively. Anti-Xa monitoring was most commonly performed in patients with cancer or obesity and was more common with VTE prophylaxis dosing. The majority of levels were therapeutic, indicating that anti-Xa monitoring may be unnecessary even in high-risk patient populations. Many out-of-range anti-Xa levels did not prompt a change in LMWH therapy. Further research is still needed to determine if anti-Xa- guided LMWH dosing improves clinical outcomes.

How to optimise anticoagulation for patients who are obese

Management of anticoagulation has become a hot topic in the last decade. Health-care professionals are encountering increasing number of patients diagnosed with a thromboembolic episode, probably as a result of heightened awareness. In addition, the recognition that hospital-acquired thrombosis causes substantial mortality has led to an emphasis on appropriate thromboprophylaxis in all patients deemed at risk of thrombosis. However, the use of anticoagulants for both treatment and prophylaxis of thrombosis can pose a challenge in individuals who are obese. There are no detailed studies in this area and as such the dosing and monitoring of anticoagulants in these individuals can be problematic.

Defects in Processes of Care for Pharmacologic Prophylaxis Are Common Among Neurosurgery Patients Who Develop In-Hospital Postoperative Venous Thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a cause of considerable morbidity and mortality in hospitalized patients. An evidence-based algorithm was developed and implemented at our institution to guide perioperative VTE prophylaxis management.

OBJECTIVE

We evaluated compliance with prescription of risk-appropriate VTE prophylaxis and administration of prescribed VTE prophylaxis in neurosurgery patients.

METHODS

This was a retrospective analysis of postoperative neurosurgery patients at a single institution with subsequent diagnosis of acute VTE during their inpatient stay. Descriptive statistics were used to characterize pharmacologic VTE prophylaxis and prescribing patterns.

RESULTS

The incidence of VTE in our neurosurgery population was 248/13,913 (1.8%). Of the 123 patients, the median time to VTE diagnosis was 96 hours after surgery (interquartile range [IQR], 58-188 hours). A total of 108 patients (87.8%) were prescribed risk-appropriate VTE prophylaxis, among whom 61 (56.5%) received all doses as prescribed. Fifty-three patients (43.1%) missed ≥1 dose of prescribed prophylaxis and the median missed doses was 3 (IQR, 0-3). The median time to first dose of pharmacologic VTE prophylaxis was 42 hours (IQR, 28-51). More than half (n = 63, 51.2%) of the VTE risk assessments contained ≥1 error, of which 15 (23.8%) would have resulted in a change in recommendation.

CONCLUSIONS

Our evidence-based VTE prophylaxis algorithm was not accurately completed in more than half of patients. Many patients who developed VTE had a defect in their VTE prophylaxis management during their inpatient stay. Research to improve optimal VTE prevention practice in neurosurgery patients is needed.

A preliminary study using rotational thromboelastometry to investigate perioperative coagulation changes and to identify hypercoagulability in obese patients undergoing total hip or knee replacement

Surgery and obesity are known risk factors for thromboembolic events due to the presence of a hypercoagulable state. Rotational thromboelastometry is a viscoelastic assay that can provide a measure of hypercoagulability via a comprehensive assessment of the coagulation process. This prospective study investigates haemostatic changes over time, presence of hypercoagulability and the association between body mass index and thromboelastometry results in patients undergoing major orthopaedic surgery. Fifty adult patients undergoing total hip or knee replacement surgery had serial thromboelastometry measures performed prior to and following surgery, and on postoperative days 1 and 3. A hypercoagulable state, defined by an ExTEM maximum clot firmness G score ≥11 dyne/cm2, was present in 28% of the patients at baseline. The mean ExTEM maximum clot firmness G score increased by an average of three units from 10 (95% confidence interval (CI) 9–11) dyne/cm2 at baseline to 13 (95% CI 13–14) dyne/cm2 on postoperative day 3, with 85% of patients having a G score ≥11 dyne/cm2. A decrease in ExTEM and InTEM clot formation time and an increase in ExTEM, InTEM and FibTEM clot amplitude at 10 minutes, alpha angle and maximum clot firmness were observed by postoperative day 3 ( P <  0.001). There was no significant difference in the mean thromboelastometry values between patients with a body mass index <35 kg/m2or ≥35 kg/m2. Although a modest association between body mass index and the ExTEM maximum clot firmness G score was observed with exploratory data analysis, further study is required in a large cohort to test the effects of confounders, validate these findings, and determine their clinical importance.

Evaluation of prophylactic dosages of Enoxaparin in non-surgical elderly patients with renal impairment

Background

Thromboprophylaxis dosing strategies using enoxaparin in elderly patients with renal disease are limited, while dose adjustments or monitoring of anti-Xa levels are recommended. We sought to evaluate the efficacy and safety of enoxaparin 20 mg versus 30 mg subcutaneously daily by comparing anti-Xa levels, thrombosis and bleeding.

Methods

We conducted a prospective, single-blinded, single-center randomized clinical trial including non-surgical patients, 70 years of age or older, with renal disease requiring thromboprophylaxis. Patients were randomized to receive either 20 mg or 30 mg of enoxaparin. The primary endpoint was peak anti-Xa levels on day 3. Secondary endpoints included trough anti-Xa levels on day 3, achievement of within range prophylactic target peak anti-Xa levels and the occurrence of hemorrhage, thrombosis, thrombocytopenia or hyperkalemia during hospitalization.

Results

Thirty-two patients were recruited and sixteen patients were randomized to each arm. Mean peak anti-Xa level was significantly higher in 30 mg arm (n = 13) compared to the 20 mg arm (n = 11) 0.26 ± 0.11, 95%CI (0.18–0.34), versus 0.14 ± 0.09, 95CI (0.08–0.19) UI/ml, respectively; p = 0.004. Mean trough anti-Xa level was higher in 30 mg arm (n = 10) compared to the 20 mg arm (n = 16), 0.06 ± 0.03, 95CI (0.04–0.08) versus 0.03 ± 0.03, 95CI (0.01–0.05) UI/ml, respectively; p = 0.044. Bleeding events reported in the 30 mg arm were one retroperitoneal bleed requiring multiple transfusions, and in the 20 mg arm one hematuria. No thrombotic events were reported.

Conclusion

Peak anti-Xa levels provided by enoxaparin 20 mg were lower than the desired range for thromboprophylaxis in comparison to enoxaparin 30 mg.

Trial registration

The trial was retrospectively registered on ClinicalTrials.gov identifier: NCT03158792. Registered: May 18, 2017.

Anti-Xa activity by weight in critically ill patients receiving unfractionated heparin for venous thromboembolism prophylaxis

PURPOSE

This study compared anti-Xa activity in critically ill patients receiving UFH for VTE prophylaxis between two weight groups (<100 kg vs ≥100 kg).

METHODS

This prospective, observational study included critically ill patients on UFH 5000 or 7500 units every 8 h. A peak and trough anti-Xa activity assay was ordered for each patient at steady state. Goal peak anti-Xa activity was 0.1-0.3 units/mL.

RESULTS

From March 2017 to June 2018, 75 patients were enrolled with 44 in the <100 kg group and 31 in the ≥100 kg group. There was no significant difference in the percentage of patients with peak anti-Xa activity within goal range between patients <100 kg and ≥ 100 kg (55.3% vs 35.7%, p = 0.12). The odds ratio for achieving peak anti-Xa activity within goal range as weight-based dose increased was 1.03 (95% CI 0.99-1.07). No differences were found in trough anti-Xa activity, VTE, bleeding, length of stay, or death.

CONCLUSIONS

Though only one-third of patients ≥100 kg had peak anti-Xa activity within goal range, no significant difference was found between the weight groups. Additional prospective studies with adequate sample sizes are warranted to further investigate appropriate weight-based dosing of UFH in critically ill patients.

The Crashing Obese Patient

Emergency physicians (EP) frequently resuscitate and manage critically ill patients. Resuscitation of the crashing obese patient presents a unique challenge for even the most skilled physician. Changes in anatomy, metabolic demand, cardiopulmonary reserve, ventilation, circulation, and pharmacokinetics require special consideration. This article focuses on critical components in the resuscitation of the crashing obese patient in the emergency department, namely intubation, mechanical ventilation, circulatory resuscitation, and pharmacotherapy. To minimize morbidity and mortality, it is imperative that the EP be familiar with the pearls and pitfalls discussed within this article.

Heparin Increases Food Intake through AgRP Neurons

Although the widely used anticoagulant drug heparin has been shown to have many other biological functions independent of its anticoagulant role, its effects on energy homeostasis are unknown. Here, we demonstrate that heparin level is negatively associated with nutritional states and that heparin treatment increases food intake and body weight gain. By using electrophysiological, pharmacological, molecular biological, and chemogenetic approaches, we provide evidence that heparin increases food intake by stimulating AgRP neurons and increasing AgRP release. Our results support a model whereby heparin competes with insulin for insulin receptor binding on AgRP neurons, and by doing so it inhibits FoxO1 activity to promote AgRP release and feeding. Heparin may be a potential drug target for food intake regulation and body weight control.

Zhu et al. demonstrate that heparin competes with insulin for insulin receptor binding on AgRP neurons, and by doing so it inhibits FoxO1 activity to promote AgRP release and feeding. Heparin is identified as a potential drug target for food intake regulation and body weight control.

Enoxaparin Dosing at Extremes of Weight: Literature Review and Dosing Recommendations

OBJECTIVE

To review the literature on both thromboprophylaxis and treatment of venous thromboembolism (VTE) with enoxaparin in low- and high-body-weight patients and to make dosing and monitoring recommendations in these patient populations.

DATA SOURCES

A search using PubMed was conducted (1995 to January 2018) using the following key words: enoxaparin, body weight, AND thromboprophylaxis, or AND treatment. Additional references were identified from a review of citations.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of body weight and/or body mass index (BMI) on VTE, bleeding, enoxaparin dosing, and/or anti-Xa concentrations for thromboprophylaxis and treatment-dose enoxaparin. Studies in pediatric and pregnant patients were excluded.

DATA SYNTHESIS

Optimal enoxaparin dosing strategies for VTE prophylaxis and treatment for patients at extremes of weight have not yet been elucidated by clinical trials; however, data suggest that standard dosing regimens may not be appropriate in these patients. Relevance to Patient Care and Clinical Practice: This review provides a thorough discussion on both thromboprophylaxis and treatment of VTE with enoxaparin in low- and high-body-weight patients. It includes dosing recommendations to guide clinicians caring for these patient populations.

CONCLUSIONS

Patients at extremes of weight require special consideration to determine appropriate enoxaparin doses. Specifically, low-body-weight patients may benefit from 30 mg subcutaneously daily for VTE prophylaxis, and standard weight-based dosing for VTE treatment. Conversely, in patients with BMIs ≥40 kg/m², 40 mg subcutaneously twice daily is recommended, with consideration for higher doses in patients with BMIs ≥50 kg/m².

The Effect of Obesity on Anti-Xa Concentrations in Bariatric Patients

BACKGROUND

Morbidly obese patients are at increased risk to develop venous thromboembolism (VTE), especially after bariatric surgery. Adequate postoperative thrombosis prophylaxis is of utmost importance. It is assumed that morbidly obese patients need higher doses of low molecular weight heparin (LMWH) compared to normal-weight patients; however, current guidelines based on relative efficacy in obese populations are lacking.

OBJECTIVES

First, we will evaluate the relationship between body weight descriptors and anti-Xa activity prospectively. Second, we will determine the dose-linearity of LMWH in morbidly obese patients.

SETTING

This study was performed in a general hospital specialized in bariatric surgery.

METHODS

Patients were scheduled for a Roux-en-Y gastric bypass with a total bodyweight (TBW) of ≥ 140 kg. Patients (n = 50, 64% female) received a daily postoperative dose of 5700 IU of nadroparin for 4 weeks. Anti-Xa activity was determined 4 h after the last nadroparin administration. To determine the dose linearity, anti-Xa was determined following a preoperative dose of 2850 IU nadroparin in another 50 patients (52%).

RESULTS

TBW of the complete group was 148.5 ± 12.6 kg. Mean anti-Xa activity following 5700 IU nadroparin was 0.19 ± 0.07 IU/mL. Of all patients, 32% had anti-Xa levels below the prophylactic range. Anti-Xa activity inversely correlated with TBW (correlation coefficient - 0.410) and lean body weight (LBW; correlation coefficient - 0.447); 67% of patients with a LBW ≥ 80 kg had insufficient anti-Xa activity concentrations. No VTE events occurred.

CONCLUSIONS

In morbidly obese patients, a postoperative dose of 5700 IU of nadroparin resulted in subprophylactic exposure in a significant proportion of patients. Especially in patients with LBW ≥ 80 kg, a higher dose may potentially be required to reach adequate prophylactic anti-Xa levels.

Treatment of venous thromboembolism with rivaroxaban in relation to body weight

The pharmacokinetics of oral rivaroxaban are highly predictable and only affected to a limited extent by bodyweight; therefore, dose adjustments for bodyweight are not required. However, this raises concerns among physicians for potential under- or overdosing. This substudy of the randomised EINSTEIN DVT and EINSTEIN PE trials, which compared rivaroxaban with enoxaparin/vitamin K antagonist (VKA) therapy, aimed to determine the incidence of major bleeding in patients with a low bodyweight and recurrent venous thromboembolism (VTE) in patients with a high bodyweight during rivaroxaban or enoxaparin/VKA therapy. More than 8,000 patients with objectively diagnosed deepvein thrombosis or pulmonary embolism were included. Adjusted hazard ratios for recurrent VTE and bleeding were calculated using the Cox proportional hazards model. Analyses were performed for both the first 21 days of treatment and the whole treatment period. For rivaroxaban recipients, there was no association between bodyweight or body mass index (BMI) and risk of recurrent VTE (ptrend=0.87 and 0.62, respectively), major bleeding (ptrend=0.24 and 0.36, respectively) or clinically relevant bleeding (ptrend=0.17 and 0.63, respectively). Major bleeding events were numerically lower in rivaroxaban patients across all bodyweight and BMI categories. Hazard ratios for rivaroxaban vs enoxaparin/VKA were similar in all bodyweight and BMI categories, both during the first 21 days and the whole treatment period. The fixed-dose rivaroxaban regimen is not associated with an increased risk of major bleeding or recurrent VTE in patients with either a low or high bodyweight. A high BMI was not associated with an increased risk of recurrent VTE during anticoagulation.

Note: This study was presented at the 25th Congress of the International Society on Thrombosis and Haemostasis; June, 2015, Toronto, Canada. Trial registration: EINSTEIN DVT (NCT00440193), EINSTEIN PE (NCT00439777).

Epidemiology and pathophysiology of venous thromboembolism: similarities with atherothrombosis and the role of inflammation

Venous thromboembolism (VTE) is a multifactorial disease. Major provoking factors (e. g. surgery, cancer, major trauma, and immobilisation) are identified in 50–60 % of patients, while the remaining cases are classified as unprovoked. However, minor predisposing conditions may be detectable in these patients, possibly concurring to the pathophysiology of the disease, especially when co-existing. In recent years, the role of chronic inflammatory disorders, infectious diseases and traditional cardiovascular risk factors has been extensively investigated. Inflammation, with its underlying prothrombotic state, could be the potential link between these risk factors, as well as the explanation for the reported association between arterial and venous thromboembolic events.

Perioperative bleeding and blood transfusion are major risk factors for venous thromboembolism following bariatric surgery

BACKGROUND

Morbidly obese patients are at increased risk for venous thromboembolism (VTE) after bariatric surgery. Perioperative chemoprophylaxis is used routinely with bariatric surgery to decrease the risk of VTE. When bleeding occurs, routine chemoprophylaxis is often withheld due to concerns about inciting another bleeding event. We sought to evaluate the relationship between perioperative bleeding and postoperative VTE in bariatric surgery.

METHODS

The American College of Surgeons-National Surgical Quality Improvement Program (NSQIP) dataset between 2012 and 2014 was queried to identify patients who underwent bariatric surgery. Gastric bypass (n = 28,145), sleeve gastrectomy (n = 30,080), bariatric revision (n = 324), and biliopancreatic diversion procedures (n = 492) were included. Univariate and multivariate regressions were used to determine perioperative factors predictive of postoperative VTE within 30 days in patients who experience a bleeding complication necessitating transfusion.

RESULTS

The rate of bleeding necessitating transfusion was 1.3%. Bleeding was significantly more likely to occur in gastric bypass compared to sleeve gastrectomy (1.6 vs. 1.0%) (p < 0.0001). For all surgeries, increased age, length of stay, operative time, and comorbidities including hypertension, dyspnea with moderate exertion, partially dependent functional status, bleeding disorder, transfusion prior to surgery, ASA class III/IV, and metabolic syndrome increased the perioperative bleeding risk (p < 0.05). Multivariate analysis revealed that the rate of VTE was significantly higher after blood transfusion [Odds Ratio (OR) = 4.7; 95% CI 2.9-7.9; p < 0.0001). Predictive risk factors for VTE after transfusion included previous bleeding disorder, ASA class III or IV, and COPD (p < 0.05).

CONCLUSIONS

Bariatric surgery patients who receive postoperative blood transfusion are at a significantly increased risk for VTE. The etiology of VTE in those who are transfused is likely multifactorial and possibly related to withholding chemoprophylaxis and the potential of a hypercoagulable state induced by the transfusion. In those who bleed, consideration should be given to reinitiating chemoprophylaxis when safe, extending treatment after discharge, and screening ultrasound.

Fast-Track in Bariatric and Metabolic Surgery: Feasibility and Cost Analysis Through a Matched-Cohort Study in a Single Centre

BACKGROUND

Due to the rise in severe obesity in Western countries and the increase in bariatric surgery, enhanced recovery (ER) pathways should be developed and promoted.

METHODS

A monocentric prospective series of 103 bariatric surgery patients managed with the ER pathway (group ER) was compared with a retrospective and immediately previous series of 103 patients managed with standard care (group CS). The aim of the present study was to assess and compare the differences in terms of mean postoperative length of stay (LOS), costs for surgery and recovery, and the differences in terms of complications, readmission, and reoperation rate in the short term between the ER and CS groups.

RESULTS

The mean LOS was 4.18 days in group CS and 1.79 days in group ER (p < 0.0001). The mean operative time (OT) per patient was 190.20 min in the group CS and 133.54 min in the group ER, resulting in an average cost of 7272.57€ per patient in group CS and 5424.09€ per patient in group ER. The average recovery cost was 1809.94€ for the group CS series and 775.07 for the group ER one. Overall complications (Clavien-Dindo up to II) occurred in 6 patients (5.8 %) in group CS and in 2 patients (1.9 %) in group ER (p = 0.149) and specific complications (Clavien-Dindo IIIb) occurred for 9 patients (8.7 %) in Group CS and for 14 patients (13.5 %) in group ER (p = 0.268) after hospital discharge within 1-month of follow-up. Twelve patients (11.5 %) in group CS and 13 (12.5 %) in group ER were readmitted after discharge (p = 0.831) within 1-month of follow-up; 8 patients (7.7 %) in group CS versus 9 patients (8.8 %) in group ER needed to be reoperated (p = 0.800) within 1-month follow-up.

CONCLUSIONS

Enhanced recovery pathway reduces significantly LOS in bariatric surgical patients and shortens the mean OT of the procedure, with no significant differences in terms of surgical outcomes. Furthermore, recovery charges were lower and operative time was shorter allowing for procedural cost reduction.

Obesity Paradox in Patients With Deep Venous Thrombosis

We aimed to investigate the association between obesity and deep venous thrombosis (DVT) in a country with a high prevalence of obesity. This is a retrospective cohort study of patients who presented with DVT between 2008 and 2012. Data were analyzed and compared based on body mass index (BMI), and patients were classified into normal (<25), overweight (≥25 to <30), obese I (30 to <35), obese II (35 to <40), and obese III (≥40). Among 662 patients with DVT, 28% were overweight and 49% were obese. The mean age was 50.3 (16.5) years, and 51% were females. Diabetes mellitus and prior venous thromboembolism were significantly higher among obese patients. History of malignancy was more common in nonobese patients. Protein S and antithrombin III deficiency and hyperhomocysteinemia were more prevalent among morbid obese patients. Also, obese patients had higher incidence of thrombosis in the distal veins ( P = .03). Warfarin use and long-term therapy were more frequent in obese than nonobese. Postthrombotic syndrome was comparable in obese and nonobese groups. Recurrent DVT was higher in obese I ( P < .01), whereas mortality rates were greater in nonobese groups ( P = .001). Malignancy, diabetes mellitus, and common femoral vein involvement were predictors of mortality, whereas BMI ≥30 was the predictor of survival. Cox regression models showed that after adjusting for age, sex, pulmonary embolism, and duration of warfarin treatment, BMI ≥40 had better survival (hazard ratio: 0.177, 95% confidence interval: 0.045-0.691, P = .013). There is a significant association between obesity and DVT. Obese patients have characteristic risk factors and better survival. This obesity paradox needs further studies to assess its clinical and pharmacotherapeutic implications.

Adjusted value of thromboprophylaxis in hospitalized obese patients: A comparative study of two regimens of enoxaparin: The ITOHENOX study

Thromboprophylaxis is a mainstay of hospital care in patients at high risk of thrombosis. Fixed doses of low-molecular-weight heparin (LMWH) are recommended for thromboprophylaxis in patients admitted to hospital for an acute medical condition. However, the distribution of LMWH is weight-based, and the efficacy of standard doses in obese patients may be decreased. Data for obese patients are mainly available in bariatric surgery with extremely obese patients who are at greater risk of venous thromboembolism than those hospitalized for a medical condition. We conducted a randomized control trial in medically obese inpatients (BMI≥30kg/m²) assessing two regimens of enoxaparin (40mg and 60mg SQ daily) in order to determine whether a stronger dosage would achieve higher anti-Xa level suitable for thromboprophylaxis. Between September 2013 and April 2015, 91 patients were included in the study (mean (±standard deviation) age was 70.4±10.7years, average BMI 37.8±6.4kg/m²). Main indications of thromboprophylaxis were mainly acute infection (50%), acute respiratory failure (10%), acute congestive heart failure (9%) and acute rheumatic disorders (18%). Average anti-Xa activity, measured 4h after the third administration of enoxaparin was 0.25±0.09IU/mL in group 1 (enoxaparin 40mg) and 0.35±0.13IU/mL in group 2 (enoxaparin 60mg) (P<10^-3). The proportions of patients with normal anti-Xa activity (between 0.32 and 0.54IU/mL) were 31% (n=11) and 69% (n=24) in group 1 and 2 respectively (P=0.007). The proportions of anti-Xa activity measurement below the normal range were 64% and 36% in group 1 and 2 (P<10^-3) respectively. Subgroup analysis focusing on high weight patients (above 100kg, n=45) showed a marked difference in the proportion of patients with normal anti-Xa activity between group 1 (9%) and 2 (44%) (P=0.009). No venous thromboembolism occurred during the study and one patient in group 1 died because of hemorrhagic shock due to a gastric ulcer. Incidence of adverse events was not different between the two groups (P=0.52). In conclusion, the ITOHENOX study shows in medically obese inpatients that thromboprophylaxis with enoxaparin 60mg provides higher control of anti-Xa activity, without more bleeding complications than the standard enoxaparin regimen. This trial is registered with ClinicalTrials.gov, number NCT01707732.

Best anaesthetic drug strategy for morbidly obese patients

PURPOSE OF REVIEW

The purpose of this review is to describe an evidence-based drug strategy applicable to any obese patient, rather than to present one standard 'ideal' anaesthetic drug combination. The ultimate choice of specific drugs in any given situation will depend upon clinician experience, patient specifics, and drug availability. The fundamental principle in anaesthesia for the obese patient is to use the shortest acting, least fat soluble agents to ensure rapid recovery to safe levels of alertness and mobility.

RECENT FINDINGS

No new drugs have been introduced over the past few years, but we have seen an introduction of enhanced recovery after surgery-based protocols into bariatric surgery. Our understanding of how obesity affects pharmacokinetics/dynamics of our drugs is improving, with new and better use of established drugs. Allometric scaling is being tested in the different pharmacokinetic/dynamic models used in target controlled infusion devices, with improved performance as a result. Obstructive sleep apnoea has a significant impact upon outcome and utilization of clinical resources, including critical care beds. If an improved drug dosing strategy will reduce this impact, then this would be a step forward.

SUMMARY

This review introduces newer findings to help us use anaesthetic and analgesic drugs more safely in the morbidly obese. However, there remain many areas of uncertainty with a lack of consensus on many issues.

Incidence of catheter-related thrombosis in acute leukemia patients: a comparative, retrospective study of the safety of peripherally inserted vs. centrally inserted central venous catheters

Central venous catheters are a leading cause of upper-extremity deep vein thrombosis. Concomitant severe thrombocytopenia makes anticoagulation for catheter-related thrombosis (CRT) in patients with acute leukemia (AL) a challenge. Incidence of CRT has been reported to be increased in those with peripherally inserted central catheters (PICC) vs. those with centrally inserted ones (CICC). Our objective is to compare the incidence rate of CRT in leukemia inpatients who received either a PICC vs. CICC. We retrospectively reviewed adult inpatients admitted to hematology wards with a new diagnosis of AL and who received either a PICC or a CICC. Baseline patient and catheter characteristics were recorded. Our primary outcome was the incidence rate of CRT in each group. The secondary outcomes included rates of infectious and mechanical complications. Six hundred sixty-three patients received at least one PICC (338) or CICC (325) insertion. A total of 1331 insertions were recorded, with 82 (11.7 %) and 41 (6.5 %) CRT in the PICC and CICC groups, respectively. The incidence rates were 1.89 and 0.52 per 1000 catheter day in the PICC and CICC groups, respectively. A PICC, when compared to CICC, was a significant risk factor for CRT (sHR 2.5, p < 0.0001). The prevalence and incidence rates of CRT in our AL patients were higher than predicted for a general cancer patient population. These rates were higher in the PICC group compared to the CICC group. We recommend careful consideration of thrombotic and bleeding risks of AL inpatients when choosing a central venous catheter.

Body mass index strongly impacts the diagnosis and incidence of heparin-induced thrombocytopenia in the surgical intensive care unit

BACKGROUND

The obese state has been linked to several immune-mediated conditions. Our objective was to examine the association of body mass index (BMI) with the diagnosis of heparin-induced thrombocytopenia (HIT).

METHODS

Prospectively collected data on patients in the surgical and cardiac intensive care unit suspected of having HIT between January 2007 and August 2014 were analyzed. Patients were categorized into five discrete BMI (kg/m) groups and compared. Data collected included Warkentin 4-T scores, antiplatelet factor 4 (anti-PF4OD) values, serotonin release assay values, and thromboembolic diseases. HIT positivity was defined as serotonin release assay value greater than 20%.

RESULTS

Of 304 patients meeting inclusion criteria, mean (SD) age was 62.1 (16.5) years, 59% were male, and mean (SD) BMI was 27 (6) kg/m. Thirty-six (12%) were positive for HIT. Incidence of HIT increased progressively with BMI (0%, 8%, 11%, 19%, 36%; p < 0.001). Compared with patients with normal BMI, patients with a BMI of 30 kg/m to 39.9 kg/m had a 200% increase in the odds for HIT (odds ratio [OR], 2.94; 95% confidence interval [CI], 1.20-7.54; p = 0.019), while patients with a BMI of 40 kg/m or greater had a 600% increase (OR, 6.98; 95% CI, 1.59-28.2; p = 0.012). After regression analysis, BMI remained an independent predictor of the development of HIT (adjusted OR per kg/m, 1.08; 95% CI, 1.02-1.14; p = 0.010). Anti-PF4OD values greater than or equal to 2.0 also increased with BMI (p < 0.001). In-hospital mortality increased significantly with BMI above normal (p = 0.026). Warkentin 4-T scores, deep venous thrombosis, pulmonary embolism, and stroke incidence did not correlate with changes in BMI.

CONCLUSION

Increasing BMI seems to be strongly associated with increased rates of HIT in intensive care unit patients. Obesity is an important new clinical variable for estimating the pretest probability of HIT, and patient "thickness" could be considered a fifth "T" of the 4-T scoring system. Additional biochemical work is indicated to decipher the role of obesity in this immune-mediated condition.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.