The use of heparin in patients in whom a pulmonary embolism is suspected after total hip arthroplasty

Bridging therapy for oral anticoagulation increases the risk for bleeding-related complications in total joint arthroplasty

Background

Patients scheduled for elective surgery with a high risk of thromboembolism require anticoagulation bridging therapy perioperatively. The purpose of this study was to assess the risk of thromboembolic events and bleeding-related complications after total hip and knee arthroplasty in patients requiring bridging therapy for anticoagulants.

Methods

A retrospective cohort study of all patients with primary total hip or total knee replacement in a 4-year period was performed. Outcome measures were blood loss, thromboembolic and bleeding-related complications and hospital stay.

Results

Bridged patients had more blood loss and higher complication rates than the control group. Most complications were bleeding-related, and there were no thromboembolic events. Seven of the 14 (50 %) total hip patients bridged with unfractioned heparin required reoperation (three patients with ischial neuropraxia due to hematoma). There were two bleeding-related deaths in total hip patients bridged with low-molecular-weight heparin. Mean hospital stay was significantly longer in unfractioned heparin bridging.

Conclusion

In this study, there was a significant increase in bleeding-related complications in total joint replacement with bridging therapy compared to prophylaxis. This risk was highest in patients with total hip arthroplasty. There were no thromboembolic events in bridged patients.

Overdiagnosis of pulmonary embolism: evaluation of a hypoxia algorithm designed to avoid this catastrophic problem

BACKGROUND

We observed a substantial increase in the incidence of pulmonary embolism (PE) after total joint arthroplasty (TJA) when multidetector computerized tomography (MDCT) replaced ventilation-perfusion (V/Q) scans as the diagnostic modality of choice. We questioned whether this resulted from the detection of clinically unimportant PE with the more sensitive MDCT and in 2007 instituted a hypoxia protocol to enhance the detection of PE.

QUESTIONS/PURPOSES

We determined whether this new hypoxia protocol increased the specificity of our workups for suspected clinically important PE in the immediate postoperative period without affecting patient morbidity and mortality.

PATIENTS AND METHODS

We compared the frequency of MDCT, V/Q scan and total investigations, incidence of PE, and overall mortality rates in the 3 years prior (January 2003 to December 2006) and 2 years after (January 2007 to November 2009) the implementation of the algorithm.

RESULTS

After instituting the protocol, we observed a trend toward a decrease in the number of patients worked up for PE (4.6 to 4.0 per 100 TJAs, 13.5% decrease). At the same time, there was an increase in the percent of positive findings of PE per workup for PE (23-33 positive PEs per 100 patients, 40.5% increase). All-cause mortality rates decreased for the 30-day period (3.1 to 1.4 per 1000 TJAs, 53.5% decrease) and the 90-day period (5.0 to 2.6 per 1000 TJAs, 48.3% decrease).

CONCLUSIONS

With the implementation of this algorithm, the specificity of our management of postoperative hypoxia and suspected clinically important PE improved without affecting patient morbidity or mortality.

High incidence of complications from enoxaparin treatment after arthroplasty

Pulmonary embolism (PE) complicates 1% to 10% of total joint arthroplasties and generally requires immediate anticoagulation. Low-molecular-weight heparins have supplanted unfractionated heparin as the treatment of choice for PE and hold a 1A recommendation from the American College of Chest Physicians for this indication. However, the complications of enoxaparin treatment begun in close proximity to arthroplasty surgery are not well described. We examined the records of 135 patients who underwent total joint arthroplasty, experienced an in-hospital PE, and received treatment with enoxaparin at therapeutic doses (1 mg/kg body weight). The type and frequency of complications were determined and classified as major or minor. Twenty-seven percent of patients experienced minor complications and 10% experienced major complications. The incidence of major bleeding was substantially higher than rates reported for nonsurgical patients. The overall complication rate of enoxaparin treatment is similar to the rate of complications reported for unfractionated heparin treatment in this setting, but the complications are less severe.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Relationship of inferior vena cava filter usage in post-surgical patients by various surgical and medical subspecialists

Venous thromboembolism is a common and often fatal problem in postsurgical patients. These patients are usually treated with either therapeutic anticoagulation or the placement of inferior vena cava (IVC) filters. Controversy surrounds the use of IVC filters, because no data exist proving survival benefit. In this study, 264 inpatient medical records of patients who underwent major surgical procedures and had the diagnosis of deep venous thrombosis or pulmonary embolism were examined. Among these patients, those who received IVC filters were identified, and the documented indications for filter placement were reviewed. Rates of IVC filter placement per venous thromboembolism event and specific indications were examined across surgical subspecialties and by type of medical consultant. Sixty percent of patients received IVC filters. IVC filter placement rates varied significantly across surgical subspecialties (p <0.0001), with the highest rate in the orthopedic surgery subgroup (80%). Rates of IVC filter use also differed significantly (p <0.0007) between medical consultants who specialized in antithrombotic medicine (46.8%) and those who did not (68.3%). Significant differences also existed in specific indications for filter placement between medical and surgical subspecialties. In conclusion, most of this study's population received IVC filters. Rates of IVC filter placement varied by the specialties of surgeons and medical consultants. The heterogeneity of treatment strategies coupled with the lack of data for this patient population highlights the need for future prospective studies to guide evidence-based treatment.

Does "excessive" anticoagulation predispose to periprosthetic infection?

Although persistent drainage and hematoma formation are recognized risk factors for the development of periprosthetic infection, it is not known if excess anticoagulation is a predisposing factor. We conducted a 2 to 1 case-control study with 78 cases who underwent revision for septic failure. The controls underwent the same index procedure but did not develop consequent infection. Patient comorbidities, medications, intraoperative, and postoperative factors were compared. Postoperative wound complications including development of hematoma and wound drainage were significant risk factors for periprosthetic infection. A mean international normalized ratio of greater than 1.5 was found to be more prevalent in patients who developed postoperative wound complications and subsequent periprosthetic infection. Cautious anticoagulation to prevent hematoma formation and/or wound drainage is critical to prevent periprosthetic infection and its undesirable consequences.

The inferior vena cava filter is effective in preventing fatal pulmonary embolus after hip and knee arthroplasties

Thromboembolic disease is a relatively common and potentially devastating complication of joint arthroplasty. Mechanical and chemical prophylaxes are effective in reducing the incidence of this complication. Inferior vena cava (IVC) filters have been used to prevent the propagation and/or migration of venous emboli into the pulmonary circulation. This article reports on a cohort of joint arthroplasty patients either with confirmed pulmonary embolism or at high risk of developing pulmonary emboli in whom an IVC filter was implanted. Using the institutional database, 95 joint arthroplasty patients who received an IVC filter were identified. The IVC filter was effective in preventing fatal pulmonary emboli in all patients. The IVC filter is a valuable and effective modality in preventing a fatal outcome of thromboembolism in patients with established thromboembolism.

Validity of index of suspicion for pulmonary embolism after hip arthroplasty

Pulmonary embolism after total hip arthroplasty is problematic, and intravenous heparin treatment in the absence of pulmonary embolism carries risk. Algorithms for treating pulmonary embolism often cite clinical index of suspicion as a basis for initiating intravenous heparin, but most information regarding variables to predict pulmonary embolism originate from studies of patients rather than only from patients who had arthroplasty. We studied the hypothesis that a more homogenous subpopulation, patients who had total hip arthroplasty, may have findings more accurately predictive of pulmonary embolism. One hundred fifty records of patients who had total hip arthroplasty who were suspected of having pulmonary embolism and who were evaluated for pulmonary embolism were assessed. Complaints, physical findings, heparinization status, and test results were analyzed with univariate and multivariate assessments to determine predictors of pulmonary embolism. No significant differences were found between patients with or without pulmonary embolism regarding subjective complaints, physical examination, blood gas results, electrocardiogram findings, radiographs of the chest, and imaging of the veins of the legs. All attempts to model these variables into an index of suspicion that accurately predicted pulmonary embolism were unsuccessful. We advise adherence to established treatment algorithms rather than clinical suspicion when deciding whether to initiate heparin therapy.

Severe postoperative haemorrhage and airway obstruction following high-dose enoxaparin

Unfractionated heparin infusion may be a more suitable choice of anticoagulant treatment in patients with venous thromboembolism in the immediate postoperative period.