Preoperative prediction of postoperative deep vein thrombosis

Challenges of morbid obesity in gynecological practice

Obesity is currently a global pandemic, with increasing trends worldwide. Data from the WHO, US CDC, and the UK show an increasing trend, with 50% and 25% of the US population expected to be obese and morbidly obese by 2030. Obesity affects several aspects of health, with increased risks of cardiovascular disease, diabetes, metabolic syndrome, and several malignancies. Morbid obesity significantly impacts several aspects of female life and health, from adolescence, through the reproductive years, to the postmenopausal age group. In gynecology, there is a higher prevalence of menstrual disorders and infertility and reduced success rates of assisted reproduction; increased risk of miscarriage; pelvic organ prolapse; and endometrial, ovarian, and breast cancers. Surgery in the patient with morbid obesity is associated with several logistical challenges as well as increased surgical and peri-operative risks and increased cost. In this review, we provide an overview of the current literature, with a focus on challenges of morbid obesity in gynecological practice.

The Inflammatory Profile of Obesity and the Role on Pulmonary Bacterial and Viral Infections

Obesity is a globally increasing health problem, entailing diverse comorbidities such as infectious diseases. An obese weight status has marked effects on lung function that can be attributed to mechanical dysfunctions. Moreover, the alterations of adipocyte-derived signal mediators strongly influence the regulation of inflammation, resulting in chronic low-grade inflammation. Our review summarizes the known effects regarding pulmonary bacterial and viral infections. For this, we discuss model systems that allow mechanistic investigation of the interplay between obesity and lung infections. Overall, obesity gives rise to a higher susceptibility to infectious pathogens, but the pathogenetic process is not clearly defined. Whereas, viral infections often show a more severe course in obese patients, the same patients seem to have a survival benefit during bacterial infections. In particular, we summarize the main mechanical impairments in the pulmonary tract caused by obesity. Moreover, we outline the main secretory changes within the expanded adipose tissue mass, resulting in chronic low-grade inflammation. Finally, we connect these altered host factors to the influence of obesity on the development of lung infection by summarizing observations from clinical and experimental data.

Determination of Risk Factors for Venous Thromboembolism by an Adapted Caprini Scoring System in Surgical Patients

Venous thromboembolism (VTE) is a frequent preventable complication among surgical patients. Precise risk assessment is a necessary step for providing appropriate thromboprophylaxis and reducing mortality as well as morbidity caused by VTE. We carried out this work to define the rate of VTE postoperatively, following a Caprini score, and to determine VTE risk factors through a modified Caprini risk scoring system. This multicenter, observational, cohort study involved 2,790,027 patients who underwent surgery in four Vietnamese hospitals from 01/2017 to 12/2018. All patients who were evaluated before surgery by using a Caprini risk assessment model (RAM) and monitored within 90 days after surgery. The endpoint of the study was ultrasound-confirmed VTE. Our data showed that the 90-day postoperative VTE was found in 3068 patients. Most of VTE (46.97%) cases were found in the highest risk group (Caprini score > 5). A total of 37.19% were observed in the high risk group, while the rest (15.84%) were from low to moderate risk groups. The likelihood of occurring VTE was heightened 2.83 times for patients with a Caprini score of 3–4, 4.83 times for a Caprini score of 5–6, 8.84 times for a score of 7–8, and 11.42 times for a score of >8, comparing to ones with a score of 0 to 2 (all p values < 0.05). Thus, the frequency of postoperative VTE rises substantially, according to the advanced Caprini score. Further categorizing patients among the highest risk group need delivering more appropriate thromboprophylaxis.

The Plasma Fibrinogen Level and Vascular Diseases

An increase in the level of plasma fibrinogen is associated with occlusive arterial diseases, venous thrombo-embolism and may precede disseminated intravascular coagulation. In addition fibrinogen levels may be predictive of fatal coronary artery disease and post-operative venous thrombosis. It is possible that fibrinogen may produce its effects by increase in blood and plasma viscosity, by arterial wall infiltration or by its effects on platelet function. Acute reduction in fibrinogen levels by ancrod (Arvin) alters all these parameters and may return them to normal. As yet no study has been carried out with long term reduction of fibrinogen by stanozolol but this is now feasible and such a trial is indicated.

Defective Fibrinolysis in Venous Thrombosis

In previous studies a variety of attempts have been made to define laboratory tests which could predict patients who would develop deep vein thrombosis post-operatively. Such tests included the partial thromboplastin time, haematocrit and platelet adhesiveness. In this study patients undergoing gynaecological surgery were screened in advance with a panel of clinical measurements and laboratory tests and the development of DVT was noted using 125I-fibrinogen leg scanning. The values for the selected variables were analysed using logistic discrimination. The factors with the greatest prediction were the euglobulin lysis time, age, varicose veins, serum FR-antigen and percentage overweight for height.

When this formula was applied to a further group of patients it allowed a ‘high risk’ group to be defined and these were given low-dose heparin with a significant reduction in the incidence of post-operative DVT.

An unexpected finding was that patients who smoked cigarettes appeared to be protected from post-operative DVT.

Relationship between Blood Groups (ABO) and Varicose Veins of the Lower Limbs. A Case-Control Study

Numerous studies have already shown the existence of a relationship between blood groups of the ABO system and certain vascular diseases: group A and atheromatous disease1,4,5,7,9,12; group A and deep venous thrombosis of the lower limbs6,11,13. However, no study has reported an association between varicose veins and the ABO blood groups.

The aim of this study was to investigate the possible existence of such an association.

Deep-vein thrombosis prophylaxis in foot and ankle surgery: what is the current state of practice?

BACKGROUND

When contemplating thromboprophylaxis for patients undergoing elective foot and ankle surgery the potential for complications secondary to venous thromboembolism (VTE) must be balanced against the cost, risk, and effectiveness of prophylactic treatment. The incidence of pulmonary embolism (PE) following foot and ankle surgery is considerably lower than after hip or knee surgery. The purpose of this study was to assess current trends in practice regarding VTE prophylaxis among expert orthopaedic foot and ankle surgeons.

METHODS

An e-mail-based survey of active AOFAS (American Orthopaedic Foot and Ankle Society) committee members was conducted (n = 100). Surgeons were questioned as to their use, type, and duration of thromboprophylaxis following elective ankle fusion surgery. Scenarios included the following: (1) A 50-year-old woman with no risk factors; (2) a 50-year-old woman with a history of PE; and (3) a 35-year-old woman actively using birth control pills (BCPs).

RESULTS

The response rate for the survey was 80% (80/100). Replies regarding the use of thromboprophylaxis were as follows: (1) in the absence of risk factors, 57% of respondents (45/80) answered, "No prophylaxis required"; (2) for the scenario in which the patient had experienced a previous PE, 97.5% of respondents (78/80) answered, "Yes" to prophylaxis use; (3) for the scenario in which the patient was on BCP, 61.3% of respondents (49/80) stated that they would give some type of thromboprophylaxis. The most commonly recommended methods of prophylaxis were aspirin, 49% (24/49), and low-molecular-weight heparin, 47% (23/49). The recommended length of time for thromboprophylaxis varied widely, from 1 day to more than 6 weeks.

CONCLUSION

. There remains wide variation in the practice of deep-vein thrombosis thromboprophylaxis within the foot and ankle community. Because risks for foot and ankle patients differ from those in the well-studied areas of hip and knee, specific guidelines are needed for foot and ankle surgery.

LEVELS OF EVIDENCE

Level V: Expert Opinion.

Application of the Caprini risk assessment model in evaluation of non-venous thromboembolism complications in plastic and reconstructive surgery patients

BACKGROUND

The Caprini Risk Assessment Model is used to categorize patient risk for venous thromboembolism (VTE) events; its predictive associations have been repeatedly corroborated. Calculating scores involves consideration of systemic factors that may predict other postoperative complications.

OBJECTIVE

This study investigates whether Caprini scores can be applied to non-VTE complications.

METHODS

The authors undertook a retrospective chart review of 1598 encounters for a series of complex reconstructive and body contouring operations at an academic medical institution. Input variables included Caprini score components, patient comorbidities, and prophylactic use of antithrombotic drugs. Output variables were postoperative complications. Tests for proportions were performed on percentile data. Nonpercentile data were treated with comparison of means (t test). Odds ratios for complications were calculated for stratified risk groups and compared.

RESULTS

The overall complication rate was 28.03%. Deep vein thrombosis (DVT) incidence was 1.50%. Differences in age, body mass index (BMI), operation time, hypertension, diabetes, renal disease, and cancer were statistically significant between patients who experienced complications and those who did not. For DVT versus DVT-free patients, differences in sex, BMI, operation time, smoking status, diabetes, hypertension, and prior DVT were significant. Caprini scores identified 628 encounters as low risk (0-4) and 970 as high risk (>5). Dehiscence, infection, necrosis, seroma, hematoma, and overall complication rate significantly increased the incidence for the high-risk group.

CONCLUSIONS

Caprini scores can be used as valuable predictors for some non-VTE postoperative complications (dehiscence, infection, seroma, hematoma, and necrosis). In addition to VTE events, clinicians should pay special attention to clinical signs indicative of the complications listed above when dealing with high-risk, high-Caprini score patients.

Pulmonary embolism after abdominal flap breast reconstruction: prediction and prevention

BACKGROUND

Symptomatic pulmonary embolism constitutes a significant risk following abdominal flap breast reconstruction. Reported rates vary from 0 to 6 percent. The authors assessed risk factors associated with symptomatic pulmonary embolism and constructed a prediction model to identify high-risk patients.

METHODS

Patients undergoing deep inferior epigastric perforator or transverse rectus abdominis musculocutaneous flap breast reconstructions at two academic centers from January of 2005 through January of 2011 were included. Thromboprophylaxis measures included early ambulation, low-molecular-weight heparin, elastic stockings, A-V Impulse System foot pumps, and pneumatic stockings. Risk factors for symptomatic pulmonary embolism were analyzed and weights were assigned to these risk factors. Sensitivity and specificity were maximized using receiver operating characteristic curves.

RESULTS

Of 430 consecutive patients, symptomatic pulmonary embolism occurred in 17 cases (4.0 percent). Two independent predictors for symptomatic pulmonary embolism were found, body mass index higher than 25, additionally higher than 28, and the BRCA gene mutation. Operation duration and bilaterality of reconstructions were dependent on the BRCA mutation and both indirect predictors for symptomatic pulmonary embolism. Optimization of sensitivity and specificity resulted in a prediction model. No significant differences in efficacy were found between the different thromboprophylaxis measures.

CONCLUSIONS

The rate of symptomatic pulmonary embolism was 4.0 percent, despite standard thromboprophylaxis. Body mass index and BRCA were significant predictors for symptomatic pulmonary embolism. The authors integrated these factors into a prediction model, which provides a useful tool for identification of high-risk patients. This latter category may benefit from a more aggressive thromboprophylaxis approach.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Facelift complications and the risk of venous thromboembolism: a single center's experience

BACKGROUND

The number of facelifts performed in the United States has steadily increased over the past decade. Moreover, the risk of venous thromboembolism in plastic surgery has been established in recent studies.

OBJECTIVES

The authors investigate the overall complication rate in a single-center series to identify risk factors and determine the risk of venous thromboembolism.

METHODS

A retrospective chart review was performed for patients who underwent a facelift procedure at a private clinic in Atlanta, Georgia, between January 2004 and December 2010. A total of 630 patients were included. The data collected included patient demographics, comorbidities, body mass index, smoking history, operative time, and concurrent procedures. All postoperative complications were recorded.

RESULTS

The mean age of the patients in this series was 58.4±7.3 years. A small percentage of the patients were men (8.1%); 23.2% had hypertension; 4.9% were smokers; and 3.5% had a history of taking prophylactic aspirin. The mean operative time was 255.6±81.6 minutes. Almost a quarter (23.6%) of the patients underwent concurrent procedures. There were 38 complications, including 29 hematomas, two deep vein thromboses (DVTs), two eye infections, two instances of partial skin loss, and one ectropion. Risk of complications was significantly higher in men, patients over 55, and those with a body mass index>30 kg/m2. The risk of hematoma was higher (P<.05) in men, patients over 55, those with a history of hypertension, and those taking aspirin. The risk of DVT increased when the procedure time was longer than five hours. Both patients who developed DVT had undergone a facelift in combination with another procedure. There was also an increase in the risk of complications when the facelift was combined with two or more procedures.

CONCLUSIONS

Identifying various risk factors for complications, especially DVT, can help to minimize those factors in the postoperative period and treat complications effectively when they occur. The data indicate that the number of concurrent procedures is a specific risk factor for development of DVT, so care should be taken when planning for multiple treatment sites. Combining facelift with other procedures also increases the risk of complications, especially DVT.

LEVEL OF EVIDENCE

4.

Thromboembolic risk assessment and the efficacy of enoxaparin prophylaxis in excisional body contouring surgery

BACKGROUND

There is a paucity of evidence within the plastic surgery literature concerning risk stratification and management of patients with respect to thromboembolic disease. A retrospective chart review was conducted to examine whether the Davison-Caprini risk-assessment model could stratify patients undergoing excisional body contouring surgery, allowing prophylaxis to be managed in an evidence-based manner.

METHODS

Three hundred sixty excisional body contouring patients at the University of Texas Southwestern Medical Center in Dallas, Texas, under the senior authors' (J.M.K. and R.J.R.) care were reviewed. Patients were stratified into groups according to the risk-assessment model and into groups based on procedure. Patient characteristics were investigated for their effects on thromboembolic risk. Complications of enoxaparin administration were analyzed. The data were analyzed using appropriate statistical procedures.

RESULTS

The highest risk patients had a significantly increased rate of venous thromboembolism when compared with lower risk patients. Body mass index greater than 30 and hormone therapy use were associated with a significantly increased venous thromboembolism rate. Enoxaparin administration was associated with a statistically significant decrease in deep venous thrombosis in circumferential abdominoplasty patients. Enoxaparin administration was associated with higher bleeding rates.

CONCLUSIONS

Low-molecular-weight heparin may affect the incidence of postoperative thrombotic complications in some surgical populations. In this study, patients who scored greater than four risk factors were at significant risk for venous thromboembolism. Enoxaparin significantly decreased deep venous thrombosis risk in patients undergoing circumferential abdominoplasty. This demonstrates the need for a multicenter, prospective, randomized study to examine various thromboembolic therapies and associated possible complications in these patients.

Prevention of venous thromboembolism in surgical patients with breast cancer

Background

No randomized trial has yet studied venous thromboembolism (VTE) prophylaxis in patients undergoing surgery for breast cancer.

Methods

Relevant articles were identified using Medline searches. Secondary articles were identified from the reference lists of key papers.

Results and conclusion

The absence of randomized trials comparing different methods of VTE prophylaxis with controls makes an evidence-based consensus among breast cancer surgeons difficult. Intermittent pneumatic compression (IPC) and graduated compression (GC) are effective in reducing VTE without the haemorrhagic complications associated with heparin; their effects are additive. The authors suggest the following strategy. All patients undergoing surgery for breast cancer should receive both IPC and GC, with heparin reserved for those at very high risk. A controlled trial should randomize women to receive heparin or not, and all women should have both IPC and GC. The primary endpoints should be the development of VTE and/or haemorrhagic complications.

Evidence for the prevention of venous thromboembolism

Patients undergoing major orthopaedic surgery are at high risk of developing venous thromboembolism (VTE). VTE is preventable and venous prophylaxis consensus groups recommend that each patient is assessed for risk of VTE and then stratified into one of the three categories of risk. Rick stratification enables the choice of the most appropriate preventative interventions. This article examines a decision making framework for VTE prevention with particular focus on a validated risk assessment model (RAM) to facilitate risk stratification. The relevant literature is also scrutinised in terms of the best venous antithrombotic strategies, for patients undergoing major orthopaedic surgery, according to scientific evidence.

Low-Molecular-Weight Heparin and Postoperative Bleeding in Rhytidectomy

BACKGROUND

Postoperative bleeding and hematoma are unwanted complications, especially for face lifts, where the rate of hematoma is reported to be high. The authors investigated the rate of complications. As expected, the major adverse event was postoperative bleeding, requiring surgical evacuation of hematoma in 5.6 percent of cases. Plastic surgeons in Europe are currently under pressure to use low-molecular-weight heparin in every face lift patient because of the guidelines of the European Consensus Conference for Prophylaxis of Thromboembolism.

METHODS

Over a period of 1.5 years, a total of 126 patients took part in a retrospective, controlled trial on postoperative bleeding, with two comparative groups. Thirty-seven patients had received low-molecular-weight heparin; in 89 patients, no heparin thrombosis prophylaxis was used. The standard for each of the 126 rhytidectomy patients operated on was as follows: one surgeon, use of compression stockings, analgosedation, and mobilization of the patient on the day of operation.

RESULTS

The authors observed a 16.2 percent rate of postoperative bleeding in the low-molecular-weight heparin-group, compared with 1.1 percent in the group where no low-molecular-weight heparin was used. This was highly significant, especially when the Fisher's exact test was applied (p < 0.003). In 89 patients, when using compression stockings, analgosedation, and mobilization of the patient on the day of operation, the authors observed had no symptomatic thrombosis or pulmonary embolism if not using low-molecular-weight heparin.

CONCLUSIONS

The authors conclude that the rate of postoperative bleeding in face lifts under the use of low-molecular-weight heparin is higher than generally expected. As no symptomatic thrombosis or embolism without using low-molecular-weight heparin occurred, it seems that the use of low-molecular-weight heparin in face lifts is not categorically necessary in low-risk patients.

Critical care of the bariatric patient

OBJECTIVE

To synthesize the current literature on care of obese, critically ill, and bariatric surgical patients.

DATA SOURCE

A MEDLINE/PubMed search from 1966 to August 2005 was conducted using the search terms obesity, bariatric surgery, and critical illness, and a search of the Cochrane Library was also conducted.

DATA EXTRACTION AND SYNTHESIS

An increase in both the prevalence of obesity and the number of bariatric procedures performed has resulted in an increased number of obese and, specifically, bariatric surgical patients who require intensive care unit care. Obesity is a chronic inflammatory state with resultant effects on immune, metabolic, respiratory, cardiovascular, gastrointestinal, hematologic, and renal function. Principles of care of the critically ill obese patient are reviewed and then applied to critically ill bariatric surgical patients. Pharmacotherapy, vascular access, and the presentation and management of both pressure-induced rhabdomyolysis and anastomotic failure after bariatric surgery are also reviewed.

CONCLUSIONS

Obesity causes a range of pathologic effects on all major organ systems. Knowledge of these effects and issues specific to the intensive care unit care of bariatric patients can help to predict and manage complications in this population.

Preoperative Evaluation of Patients with Obesity and Obstructive Sleep Apnea

Obesity and obstructive sleep apnea are conditions frequently encountered by the anesthesiologist and may have a significant impact on perioperative outcomes. This article discusses the preoperative evaluation of patients with one or both of these conditions. The goals of the preoperative assessment are to identify issues that can adversely affect the patient. This information is critical to forming an effective plan for the perioperative care of the patient.

49, XXXXY syndrome with unilateral renal aplasia, proteinuria, and venous thromboembolism

A 28-year-old man presented with mental retardation, peculiar facial features, radioulnar synostosis, hypogonadism, aplasia of the right kidney, a moderate degree of proteinuria, and peripheral cyanosis. The activated partial thromboplastin time was shortened, and the level of plasma factor VIII was high. A chromosomal analysis revealed a 49, XXXXY karyotype. From the 10th hospital day, he suffered from sudden dyspnea following swelling of the left leg. He was diagnosed as having deep vein thrombosis and pulmonary embolism, and was successfully treated with anticoagulant therapy. This is the first case of the 49, XXXXY syndrome complicated with unilateral renal aplasia, proteinuria, and venous thromboembolism.

Evidence-based risk factors for postoperative deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a common postoperative complication that is associated with significant morbidity and mortality. Thromboprophylaxis has been shown to be underused. In the absence of prophylaxis, rates as high as 50% have been reported following orthopaedic surgery, and 25% following general surgery. Many risk factors have been suggested but there is often little evidence to support these claims.

METHODS

A systematic review was performed to determine the evidence base behind each suggested risk factor, and, where sufficient data were available, a random-effects meta-analysis was performed.

RESULTS

There is evidence to support a significant association between increased age, obesity, a past history of thromboembolism, varicose veins, the oral contraceptive pill, malignancy, Factor V Leiden gene mutation, general anaesthesia and orthopaedic surgery, with higher rates of postoperative DVT, although there remain some variables within the study designs that may lead to overestimation of effect. There is no evidence to support the suggested risk factors of hormone replacement therapy, gender, ethnicity or race, chemotherapy, other thrombophilias, cardiovascular factors, smoking and blood type.

CONCLUSIONS

An accurate knowledge of evidence-based risk factors is important in predicting and preventing postoperative DVT, and can be incorporated into a decision support system for appropriate thromboprophylaxis use.

Prevention of Venous Thromboembolism in the Plastic Surgery Patient

The term venous thromboembolism refers to a spectrum of disease that includes deep venous thrombosis and pulmonary embolism. Both deep venous thrombosis and pulmonary embolism are often clinically silent and thus difficult to diagnose, which leads to a substantial delay in treatment that results in high rates of morbidity and mortality. The purposes of this article are to help physicians determine the proper venous thromboembolism prophylaxis and to simplify the complex problem of treating venous thromboembolism. The tools provided in this article will help expedite and clarify the decision-making process.

Influence of Overweight on ICU Mortality

STUDY OBJECTIVE

Overweight patients seem to have a poorer outcome and a higher risk of complications during their stay in the ICU. We conducted a prospective study in order to examine the relationship between body mass index (BMI) and mortality among these patients.

DESIGN

Prospective clinical study.

SETTING

A 24-bed medical ICU in a university-affiliated hospital.

METHODS

All patients hospitalized in the ICU over a 1-year period were included except those dying or being discharged from the hospital within 24 h of admission. Overweight patients were defined as those having a BMI > 75th percentile of this selected ICU population. Other data collected were demographic and ICU-related data. The Mann-Whitney test was used to compare numeric data between groups (ie, obese and nonobese populations). Variables that were significantly associated with ICU mortality by univariate analysis were entered into a multiple logistic regression model, allowing the determination of independent predictors.

RESULTS

Eight hundred thirteen patients were included in the study. The limit of the upper quartile of the BMI was 27. This value was used to separate obese (n = 215) and nonobese (n = 598) groups. Significant differences between obese and nonobese patients were observed in age, length of stay in the ICU, simplified acute physiology score (SAPS) II, and ICU mortality. The observed mortality of obese patients was significantly higher than that predicted by SAPS II (32% vs 18%, respectively; p = 0.001). No difference was observed in frequency of nosocomial infection or duration of mechanical ventilation for mortality in ICU patients. Using a multivariate analysis, the predictive factors of mortality were SAPS II (p < 0.0001) and BMI > 27 (p < 0.01).

CONCLUSION

This is the first prospective study showing high BMI value as an independent prognostic factor of mortality for ICU patients. The prognostic scoring systems currently in use, which were designed to predict the mortality of ICU patients, do not include BMI or do not consider obesity. These may underestimate, therefore, the risk for the specific population of obese patients.

Obstáculos diagnósticos e desafios terapêuticos no paciente obeso

Obesidade é uma doença complexa, de mútiplas etiologias e suficientemente comum para constituir um problema de saúde pública, assim como um dilema clínico importante. Especialistas da área clínica e cirúrgica são freqüentemente desafiados pelas alterações fisiopatológicas associadas com a obesidade. Essas alterações comprometem virtualmente todos os sistemas do organismo, podendo apresentar-se como barreiras no diagnóstico e na terapêutica. Há evidências marcantes de que obesidade acarreta risco excessivo para a saúde; de fato, a mortalidade aumenta de forma aguda quando o índice de massa corporal ultrapassa 30 kg/m2, principalmente quando há distribuição central de tecido adiposo concomitante. O autor discute os efeitos da obesidade nos sistemas respitatório, cardiovascular, digestório e geniturinário. Os obstáculos enfrentados em procedimentos diagnósticos ordinários, prescrição de medicamentos, traumas, assim como descrições patológicas raras de lipomas, são apresentados.

Improved hemodynamic effectiveness and associated clinical correlations of a new intermittent pneumatic compression system in patients with chronic venous insufficiency

PURPOSE

A new intermittent pneumatic compression device (SCD Response System) has recently been shown in healthy volunteers to have the ability to detect the postcompression refilling of the calf veins and to respond by initiating the subsequent cycle when these veins are full. This has proven to be more effective in expelling blood proximally than the conventional intermittent pneumatic compression device (SCD Sequel System). The aim of this study was to test the influence of venous disease on the postcompression refill time detected by means of the SCD Response and the effectiveness of the new system in expelling blood in patients who have venous reflux caused by post-thrombotic syndrome or varicose veins.

METHODS

This open, controlled trial was conducted in an academic vascular unit with 10 patients who had post-thrombotic syndrome and 10 patients who had varicose veins. The new SCD Response System was tested against the existing SCD Sequel System in both legs in the supine, semirecumbent, and sitting positions. The refilling time sensed by means of the device was correlated with the venous filling index by using air plethysmography. The total volume of blood expelled per hour during compression was compared with that expelled by the SCD Sequel System in the same volunteers and in the same positions.

RESULTS

An inverse association was found between the mean postcompression refilling time in the sitting position and the venous filling index of the apparently healthy or less severely affected leg (r = -0.52, P =.019), the refill time being significantly shorter in patients with advanced venous disease. The SCD Response System increased the volume expelled per hour in the post-thrombotic leg, when compared with the SCD Sequel System, by 109.9% (P =.005) in the supine position, by 85.1% (P =.009) in the semirecumbent position, and by 40.2% (P =.005) in the sitting position. The corresponding results in the more severely affected leg in patients with varicose veins were 71.9% (P =.005) in the supine position, 77.9% (P =.005) in the semirecumbent position, and 55.7% (P =.013) in the sitting position. Similar improved results were also found in the contralateral leg in both groups.

CONCLUSIONS

The deflation settings of the new SCD Response System are able to be adjusted selectively, correlating with the physiological severity of chronic venous insufficiency. By achieving more frequent compression cycles, the new system is more effective than the current one in expelling blood proximally, confirming our earlier findings in healthy volunteers. Further studies testing a possible improved efficacy in preventing deep venous thrombosis in this high-risk group are justified.

Deep venous thrombosis and pulmonary embolus after face lift: a study of incidence and prophylaxis

Deep venous thrombosis and pulmonary embolus are known risks of surgery. However, the incidence of these conditions in face lift is unknown. In this study, the incidence of deep venous thrombosis/pulmonary embolus after face lift is studied and factors associated with thromboembolic complications are evaluated. One-third of the active members of the American Society for Aesthetic Plastic Surgery were randomly selected. Participating surgeons completed a one-page survey providing information on face-lift procedures during a 12-month study period. A response rate of 80 percent was achieved, with 273 of the 342 surgeons responding to the survey. A total of 9937 face-lift procedures were reported in the 1-year study period. There were 35 patients with deep venous thrombosis (0.35 percent), 14 patients with pulmonary embolus (0.14 percent), and 1 patient death in the series. Although 43.5 percent of patients underwent face lift under general anesthesia, 83.7 percent of deep venous thrombosis/pulmonary embolus events occurred with general anesthesia. For prophylaxis for deep venous thrombosis/pulmonary embolus, 19.7 percent of the surgeons used intermittent compression devices, 19.6 percent used thromboembolic disease hose or Ace wraps, and 60.7 percent used no prophylaxis. Of patients developing deep venous thrombosis/pulmonary embolus, 4.1 percent were treated prophylactically with intermittent compression devices, 36.7 percent with thromboembolic disease hose/Ace wraps, and 59.2 percent with no prophylaxis. It was found that deep venous thrombosis/pulmonary embolus after face lift is a measurable complication experienced by one of nine surgeons surveyed. Deep venous thrombosis/pulmonary embolus is more likely to occur when the procedure is performed under general anesthesia. The majority of plastic surgeons surveyed used no prophylaxis for deep venous thrombosis when performing face-lift procedures. Intermittent compression devices were associated with significantly fewer thromboembolic complications, whereas Ace wrap/thromboembolic disease hose afforded no protection against deep venous thrombosis/pulmonary embolus when used alone. In conclusion, aesthetic surgeons should consider adopting intermittent compression devices when performing face lift under general anesthesia.

Pulmonary complications of obesity

Obesity can profoundly alter pulmonary function and diminish exercise capacity by its adverse effects on respiratory mechanics, resistance within the respiratory system, respiratory muscle function, lung volumes, work and energy cost of breathing, control of breathing, and gas exchange. Weight loss can reverse many of the alterations of pulmonary function produced by obesity. Obesity places the patient at risk of aspiration pneumonia, pulmonary thromboembolism, and respiratory failure. It is the most common precipitating factor for obstructive sleep apnea and is a requirement for the obesity hypoventilation syndrome, both of which are associated with substantial morbidity and increased mortality. There are numerous medical and surgical therapies for obstructive sleep apnea and obesity hypoventilation. Weight reduction in the obese is among the most effective of these measures.

Effective risk stratification of surgical and nonsurgical patients for venous thromboembolic disease

Effective and safe methods of preventing venous thromboembolism (VTE) are now widely available, but a significant proportion of patients develop VTE either because thromboprophylaxis has not been used or because the intensity of thromboprophylaxis is not matched to the level of risk. Thromboembolic risk varies widely according to the clinical setting and presence of underlying risk factors, but VTE may not be suspected even in high-risk patients. Clinical risk factors for VTE include recent surgery, cancer, stroke, previous VTE, immobilization, and advanced age. Recent attention has focused on the role of inherited and acquired molecular factors in determining overall thromboembolic risk. These factors include the classic thrombophilias-deficiencies of antithrombin III, protein C, and protein S-and several newly described molecular risk factors: factor V Leiden, the prothrombin 20210A gene mutation, and hyperhomocysteinemia. Based on emerging knowledge of risk factors, several risk assessment models (RAMs) have been devised that stratify patients according to overall VTE risk, allowing thromboprophylaxis to be tailored appropriately. Compared with older risk assessment formulas, current RAMs are simpler and include specific recommendations for thromboprophylaxis based on the available scientific evidence. Consensus documents on VTE prevention classify patients into low-, moderate-, and high-risk categories. More recently, a new risk group, very high risk, has been described. Very-high-risk patients are especially prone to thromboembolic complications and need intensive and in some cases prolonged thromboprophylaxis.

Venous thromboembolic complications in obstetrics and gynecology with a focus on the role of low molecular weight heparin

Venous thromboembolism is a major cause of morbidity, mortality, and economic expense in the field of obstetrics and gynecology. Without prophylaxis, as many as 30% of at-risk patients will suffer deep vein thrombosis, and nearly 1% of these patients will succumb to a fatal pulmonary embolism. Both deep venous thrombosis and pulmonary embolism manifest few specific symptoms, and the presentation of these entities is often clinically silent. Therefore, a prophylactic approach is preferred. We review the pathophysiology, risk factors, prophylactic choices, and treatment of venous thromboembolic complications for the general obstetric and gynecology population. We focus on the role of low molecular weight heparin because of its convenient dosing and favorable risk/benefit profile.

Risk factor scoring for predicting venous thromboembolism in obstetric patients

OBJECTIVE

The aim of this study was to develop a risk factor scoring system for the prediction of venous thromboembolism in obstetric patients.

STUDY DESIGN

We conducted a retrospective case-control study of all pregnant or postpartum women admitted to the Jack D. Weiler Hospital from 1987 through 1998 with a discharge diagnosis indicating thromboembolism. For each study subject the three women who were delivered immediately before that index patient were selected for the control group. Data collected included the following: history of thrombosis, age, body mass index, previous abdominal surgical procedures, presence of systemic diseases, and blood type. Each patient was assigned a score that was based on the risk factors identified.

RESULTS

We identified 21 patients who had sustained thromboembolic events during pregnancy or 6 weeks post partum. Nineteen of the thromboembolic events (90%) were diagnosed during pregnancy, and these cases were distributed throughout gestation-8 (42%) in the first trimester, 2 (10%) in the second trimester, and 9 (48%) in the third trimester. Six (28%) of these patients had pulmonary embolisms. Two cases of postpartum thromboembolic events were documented. Both were cases of pulmonary embolism. There was 1 maternal death. Patients with a score >2 were at significantly increased risk for having a thromboembolism, with an odds ratio of 4.8 (P <.05). The sensitivity, specificity, positive predictive value, and negative predictive value of this cutoff point were 21%, 95%, 57%, and 78%, respectively.

CONCLUSION

Obstetric patients with high risk factor scores were at increased risk for thromboembolism.

Fibrinolysis and thrombosis

The fibrinolytic system generates plasmin, which dissolves fibrin in haemostatic plugs and in thrombi. It is often regarded simply as a secondary phenomenon responsive to the generation of thrombi but it is, rather, in dynamic balance with fibrin formation, such that abnormalities in either can lead to thrombosis. This chapter summarizes the fibrinolytic system and its regulation. It considers the components of the system in blood, both in plasma and in circulating cells, with emphasis on protease-inhibitor balance. It goes on to discuss local fibrinolytic potential in thrombi, both venous and arterial, and in the diseased vessel wall, presenting evidence that increased local inhibition of fibrinolysis by PAI-1, PAI-2 and alpha2-antiplasmin is intimately involved in thrombus stability and in the generation of fibrin-rich vessel wall lesions. Finally, it reviews the evidence that defective plasma fibrinolysis has a causal role in venous and arterial thrombosis.

The obese patient in the ICU

Data from recent surveys indicate that a staggering 34.9% of US adults are overweight. Obese adults are at in increased risk for many chronic medical conditions, and this increases the likelihood of admission to an ICU. The critically ill obese patient presents the ICU team with many unique problems. Obesity may result in significant alterations of pulmonary and cardiac function, as well as the handling of many drugs. An appreciation of these and other changes is essential in the management of the obese ICU patient. The purpose of this article is to review some of the basic concepts related to the treatment of obese patients in the ICU.

Prediction of postoperative venous thrombosis using haemostasis tests

The prediction of patients who are at sufficiently high risk of postoperative deep venous thrombosis to indicate perioperative antithrombotic prophylaxis has traditionally used only clinical risk factors. The associations of preoperative and/or postoperative haemostatic tests with postoperative deep venous thrombosis are reviewed. In general, the results support the biological concept of a preoperative and postoperative prothrombotic tendency in patients who develop deep venous thrombosis. Increased levels of coagulation activation markers and decreased assays of fibrinolytic potential show consistent relationships to postoperative deep venous thrombosis. At present, however, the clinical utility of such tests is unproven; so that at present they cannot be advocated for routine preoperative or postoperative screening.

The fibrinolytic effects of intermittent pneumatic compression: mechanism of enhanced fibrinolysis

BACKGROUND AND OBJECTIVES

Intermittent pneumatic compression (IPC) is an effective form of deep vein thrombosis prophylaxis for general surgery patients. The antithrombotic effect of IPC is thought to be the result of increased venous velocity and stimulation of endogenous fibrinolysis. However, the mechanism of enhanced fibrinolytic activity and the relative effects on normal and postthrombotic veins have not been defined. The purposes of this study are 1) to quantify changes in fibrinolytic activity with IPC; 2) to study the mechanism of fibrinolytic enhancement with IPC; and 3) to evaluate whether postthrombotic patients have the same capacity for fibrinolytic enhancement with IPC as do normal subjects.

METHODS

Twelve volunteers (6 normal and 6 postthrombotic) had 5 IPC devices applied for 120 minutes in random fashion, 1 per week x 5 weeks. The devices included single-chamber, sequential, foot, calf, and long-leg compression. Subjects had an indwelling antecubital venous cannula placed for blood drawn at baseline, 60, 120, and 180 minutes after IPC devices were applied. Global fibrinolytic activity (euglobulin fraction, fibrin plate assay), tissue plasminogen activator (tPA) antigen (Ag) and activity (Act), plasminogen activator inhibitor-1 (PAI-1) Ag and Act, alpha-2-antiplasmin-plasmin complexes, and von Willebrand factor (vWF) antigen were assayed.

RESULTS

A striking elevation in fibrinolytic activity was noted at 180 minutes with all devices in normal subjects and postthrombotic patients (p = 0.01-0.0001); however, baseline and stimulated fibrinolytic activity was attenuated in postthrombotic patients (<0.03). The tPA-Act increased only in normal subjects (3.8 +/- 1.9%) (p = 0.057), despite a decrease in plasma tPA-Ag, which was observed in both normal subjects (-12.4 +/- 3.8%) (p = 0.009) and patients (-17.2 +/- 3.1%) (p = 0.001). PAI-1-Ag decreased in both normal subjects (-13.4 +/- 3.8%) (p = 0.007) and patients (-12.0 +/- 3.1%) (p = 0.013) with a marked reduction in PAI-1-Act in both normal subjects (p = 0.003) and patients (p = 0.004). There were no changes in vWF, and alpha-2-antiplasmin-plasmin complexes increased only in postthrombotic patients (p = 0.021).

CONCLUSIONS

Stimulation of endogenous fibrinolytic activity occurs after IPC, both in normal subjects and postthrombotic patients; however, baseline and overall fibrinolytic response in postthrombotic patients is reduced. The mechanism of increased fibrinolytic activity is likely because of a reduction in PAI-1, with a resulting increase of tPA activity.

Epidemiology, risk factors and prophylaxis of venous thrombo-embolism in obstetrics and gynaecology

Venous thrombo-embolism remains a major cause of mortality and morbidity following gynaecological surgery and in association with pregnancy and delivery. Specific risk factors can be identified pre-operatively and before or during pregnancy and delivery. Clinicians and units should develop guidelines for risk assessment and the implementation of specific thromboprophylactic measures in patients considered to have significant risk. The main prophylactic techniques are unfractionated and low-molecular-weight heparins and physical methods such as graduated elastic compression stockings. It should be noted that there are particular concerns with regard to the use of pharmacological thromboprophylaxis with both heparin and warfarin in pregnancy. Unfractionated heparin is associated with osteoporotic problems, allergy and heparin-induced thrombocytopenia which can cause significant thrombotic problems. Warfarin is associated with teratogenesis and the risk of bleeding in mother and fetus. Clearly, where antenatal thromboprophylaxis is to be used, the risk of the anticoagulants employed must be weighed against the potential benefits. Such assessment might be best done prior to pregnancy in order that the patient can enter pregnancy with a clear view of the potential hazards and benefits. Low-molecular-weight heparins are being increasingly used in pregnancy but it is unclear to what extent they are safer than unfractionated heparins. However, they do appear to have substantially less risk of heparin-induced thrombocytopenia and possibly less risk of heparin-induced osteoporosis. Increasingly, thrombophilia is recognized as underlying many thrombotic problems, particularly in young women, and when the events occur in association with pregnancy. In view of the complexity in the management of such patients, it is important that they be referred to a unit with specific expertise in the management of thrombophilia.