Intramuscular veins: the most neglected source of thrombosis

Chronic Venous Insufficiency

This is a recommended evaluation and management algorithm from the Western Trauma Association (WTA) Algorithms Committee focused on the management of pharmacologic prophylaxis for venous thromboembolism (VTE) prevention in trauma patients. Because there are few related published prospective, randomized clinical trials that have generated class I data on this topic in the trauma population, these recommendations are based primarily on published prospective and retrospective cohort studies, and expert opinion of the WTA members. The final algorithm is the result of an iterative process including an initial internal review and revision by the WTA Algorithm Committee members, and then final revisions based on input during and after presentation of the algorithm to the full WTA membership. Goals The algorithm (Fig. 1) and accompanying comments represent a safe and sensible approach to reducing VTE in trauma patients. The aim for this approach was to provide updated guidelines that apply to most patients, most of the time. We recognize that there will be multiple factors that may warrant or require deviation from any single recommended algorithm and that no algorithm can completely replace expert bedside clinical judgment. We encourage institutions and clinicians to use this algorithm as a general framework in the approach to trauma patients and to customize and adapt it to better suit the specifics of that program or location.Figure 1: The WTA algorithm for VTE prophylaxis after trauma. Circled letters correspond to sections in the associated article. Algorithm circle-bubbles represent patient criteria; algorithm square-bubbles represent expert recommendations. CrCl, creatinine clearance; Hb, hemoglobin; LMWH, enoxaparin; q8h, every 8 hours; q12h, every 12 hours; UFH, unfractionated heparin.Burden of Disease Venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a potentially preventable complication after trauma. The focus of this algorithm is on optimizing the delivery of pharmacologic prophylaxis to prevent VTE and minimize any associated complications. For those trauma patients diagnosed with a DVT or PE, including distal upper extremity or calf thrombosis, specific treatments are addressed in other guidelines and will not be covered in this algorithm.1,2 Without pharmacologic prophylaxis, a 1994 study determined that the DVT rate was 58% in severely injured trauma patients who undergo serial impedance plethysmography with lower extremity contrast venography.3 In a landmark, 1996 New England Journal of Medicine publication 30 mg of subcutaneous enoxaparin twice daily performed better than 5,000 U of subcutaneous heparin twice daily at reducing DVT in moderate to severely injured trauma patients (31% vs. 44%, p = 0.04).4 The risk of major bleeding was low regardless of therapy, and importantly, the first dose of pharmacologic prophylaxis was initiated within 36 hours of the injury and continued through all surgical procedures except spinal fixation when a single preoperative dose was held.4 This study established that early, uninterrupted enoxaparin was superior to heparin at reducing VTE after trauma. In the last decade, a number of reviews and societal recommendations focused on improving the guidelines to reduce the rate of VTE and related complications after trauma.1,2,5–11 Despite this progress, debate persists regarding optimal dosing and timing of enoxaparin, including when to initiate, hold, and resume it before and after surgery or epidural placement. Trauma patients frequently receive a delayed, suboptimal dose of enoxaparin, which is then held for any potential surgical procedure despite substantial evidence that encourages early, uninterrupted pharmacologic prophylaxis. An updated algorithm on the appropriate management of VTE prophylaxis is therefore indicated. ALGORITHM The following lettered sections correspond to the letters identifying specific sections of the algorithm shown in Figure 1. In each section, we provide a brief summary of the important aspects and options that should be considered at that point in the evaluation and management process. A This algorithm is designed for adult trauma patients 18 years and older. Importantly, although younger children have a significantly lower VTE risk, older children and adolescents have a VTE risk that approaches their adult counterparts.12 Guidance for VTE prophylaxis in children can be found in the joint practice management guideline from the Pediatric Trauma Society and the Eastern Association for the Surgery of Trauma, which recommends, "pharmacologic prophylaxis be considered for children older than 15 years old and in younger postpubertal children with Injury Severity Score (ISS) greater than 25."11 B Assessment of VTE risk will assist in determining which patients require pharmacologic prophylaxis. In general, an ISS of 10 or more suggests that pharmacologic prophylaxis should be initiated as soon as possible, whereas patients with an ISS of less than 10 are at lower VTE risk and may not require pharmacologic prophylaxis.13–15 Because ISS is not calculated in real time, the Greenfield Risk Assessment Profile or the Trauma Embolic Scoring System can assist with calculating VTE risk.13–15 Patients with spine or pelvic fractures, repair of venous injury, a history of VTE, or inherited clotting disorders have increased VTE risk and should be considered for pharmacologic prophylaxis.2,13,14 Among trauma patients with minor injuries, independent predictors of increased VTE risk are increased age, obesity, and lower extremity fractures; any combination of these three characteristics should encourage initiation of pharmacologic prophylaxis.13 C Patients with minor trauma may not require pharmacologic prophylaxis. Given the related pain with injection, potential for hematoma at the injection site, cost for the medication, and nursing costs for administration, avoiding pharmacologic prophylaxis may be indicated for select low-risk patients after minor trauma. The Trauma Embolic Scoring System can be used to assess VTE risk, as patients with a low score require no pharmacologic prophylaxis because of their low VTE rate.13 Ambulatory patients with minor injuries and short hospital stays may not require pharmacologic prophylaxis. Trauma patients capable of ambulation but confined to bed because of intoxication, restraints, or other reasons should receive pharmacologic prophylaxis. In general, trauma patients who require hospital admission for more than 24 hours require pharmacologic prophylaxis, whereas those hospitalized for less than 24 hours do not. For the patients who do not receive pharmacologic prophylaxis, mechanical prophylaxis and/or aspirin are low cost and low morbidity options, although their benefit is uncertain given the low VTE rate.13–16 D Appropriate delays in pharmacologic prophylaxis may occur for those patients with an active bleed, coagulopathy, hemodynamic instability, solid organ injury, traumatic brain injury (TBI), or spinal trauma. Quantifying the risk and benefit of initiating pharmacologic prophylaxis for each patient is a challenge that is best determined by the trauma team at bedside. Detailing every indication where a delay may be indicated is outside the scope of these guidelines; several are described below. However, it is important to note that the guidance in both the literature and clinical practice supports very short delays to the initiation of pharmacologic prophylaxis, even among these cohorts. Active Bleeding, Coagulopathy, or Hemodynamic Instability Control of active bleeding is necessary before starting pharmacologic prophylaxis. In the presence of hemodynamic instability, a hemoglobin drop of greater than 2 g/dL in under 12 hours or ongoing blood transfusion is an appropriate indication to delay the initiation of pharmacologic prophylaxis.2,4 Systemic coagulopathy was previously proposed as a reason to delay pharmacologic prophylaxis with one study holding pharmacologic prophylaxis for an elevated prothrombin time of more than 3 seconds above control or a platelet count of less than 50,000 per cubic millimeter.4 More recent studies indicate that prothrombin time and platelet count are not as reliable at predicting systemic coagulopathy as viscoelastic hemostatic assays, which may demonstrate hypocoagulability and hypercoagulability after trauma.2,17–19 The hypocoagulability due to trauma largely resolves within 24 hours, after which hypercoagulability becomes prevalent. In this setting, pharmacologic prophylaxis may be considered after the initial resuscitation is complete.17,20 Deferring the initiation of pharmacologic prophylaxis during trauma-induced coagulopathy is associated with an increased VTE rate such that the initiation of pharmacologic prophylaxis is encouraged if the hypocoagulable state is expected to resolve and there are no signs of ongoing bleeding.17 Solid Organ Injury Delays occur in the initiation of pharmacologic prophylaxis for patients with solid organ injury. Several studies indicate that patients with solid organ injury who received early pharmacologic prophylaxis had lower DVT and PE rates without increased risk of failure of nonoperative management, bleeding complications, or mortality; these risks did not increase when pharmacologic prophylaxis was started within 24 hours compared with within 48 hours.20–23 Early pharmacologic prophylaxis within 12 to 24 hours appeared to be safe across moderate American Association for the Surgery of Trauma injury grade and type of solid organ injury (liver, spleen, and/or kidney), without an increased risk of bleeding that necessitated intervention or blood transfusion.21 Although those with grade IV and V injuries should be approached with caution, pharmacologic prophylaxis may be initiated within 24 hours for most patients with solid organ injury.21–23 Traumatic Brain Injury Concern for progression of TBI is a common reason for the delay in initiation of pharmacologic prophylaxis. This delay is dependent on the type of TBI; those with "cerebral contusion, localized petechial hemorrhages, or diffuse axonal damage" may safely receive pharmacologic prophylaxis without delay.4 When pharmacologic prophylaxis is appropriately delayed, the follow-up computed tomography (CT) after TBI diagnosis is an important indicator for when to initiate pharmacologic prophylaxis.24 For patients with TBI progression on the follow-up CT, exposure to pharmacologic prophylaxis is a predictor for further progression, and it should be held until a follow-up CT demonstrates no progression.24 In contrast, if the follow-up CT demonstrates no TBI progression, then pharmacologic prophylaxis should be initiated.24 Importantly, progression of TBI occurs in about 10% of patients with a stable follow-up CT, regardless of whether pharmacologic prophylaxis is provided or not.24 Those trauma centers that provide pharmacologic prophylaxis within 24 hours after TBI have significantly lower rates of VTE with no difference in rates of late neurosurgical intervention.23,25–30 Even in the setting of combat related penetrating TBI, initiating pharmacologic prophylaxis 24 hours after injury for those patients with a stable CT was safe, with similar progression rates regardless of pharmacologic prophylaxis.29 The majority of TBI patients with a stable CT may be initiated on enoxaparin within 24 hours, and nearly all TBI patients should receive pharmacologic prophylaxis within 72 hours of the time of injury.23,28,31 Spinal Trauma In the absence of pharmacologic prophylaxis, patients who undergo spine surgery or those with spine trauma, fracture, or cord injury have a high incidence of VTE,2 and delays longer than 72 hours lead to a substantial increase in the VTE rate.32 Pharmacologic prophylaxis must be initiated as soon as possible after spine surgery or any spine injury.32,33 Regimens that provide pharmacologic prophylaxis preoperatively34 or immediately after operative fixation are considered safe.4,34 When a departmental protocol was implemented that required pharmacologic prophylaxis preoperatively or the same day of spine surgery, the VTE rate decreased and the rate of spinal hematoma was unchanged.34 Similarly, pharmacologic prophylaxis initiated within 48 hours of operative fixation of traumatic spine fractures did not increase the risk of bleeding, progression of neurological injury, or postoperative complications including spinal hematoma.23,33 E Mechanical prophylaxis for moderate to high VTE risk patients is encouraged regardless of concurrent pharmacologic prophylaxis. For patients who are not started immediately on pharmacologic prophylaxis, mechanical prophylaxis with intermittent pneumatic compression and mobilization, when possible, should be encouraged. Intermittent pneumatic compression lowers the DVT incidence if no pharmacologic prophylaxis is initiated and therefore is recommended for patients with a contraindication to pharmacologic prophylaxis.2,35,36 In contrast, the addition of intermittent pneumatic compression in critically ill patients who received pharmacologic prophylaxis did not lead to a reduction in the DVT rate, although the study had a low DVT rate and only 8% of the population were trauma patients.16 Combining mechanical prophylaxis with pharmacologic prophylaxis is therefore encouraged for moderate to high VTE risk patients in part because those who received the combination had a lower incidence of symptomatic PE.35 Compression stockings do not appear to reduce the VTE rate in the presence of pharmacologic prophylaxis,16 but thigh high compression stockings may provide a benefit to those trauma patients who cannot be started on pharmacologic prophylaxis.2 Mobility is also an important component for VTE prevention, as early mobility leads to a reduction in VTE.37 A mobility protocol is safe in trauma patients and may reduce patient deconditioning besides decreasing the rate of VTE.37 Prolonged maintenance of spinal precautions is associated with an increased DVT rate and should be avoided to allow early mobility.38 F Weekly venous compression duplex should be considered in patients at high VTE risk who cannot be started or maintained on pharmacologic prophylaxis. Although debate persists, routine surveillance with venous compression duplex is not indicated or feasible for all trauma patients.2 Routine surveillance duplex after trauma does not decrease the risk of PE or fatal PE, and false-positive results lead to unnecessary therapeutic anticoagulation.2 In trauma patients at low VTE risk, the high cost and low yield of acute, clinically relevant findings suggest that the practice may be avoided. Some institutions advocate for routine surveillance in low-risk trauma patients to identify both acute and preexisting DVT, which may help identify and treat the related complications such as venous insufficiency, venous stasis ulcers, or pain with ambulation.39 For trauma patients at high VTE risk, routine surveillance duplex is associated with a reduced PE rate.39 The Greenfield Risk Assessment Profile can identify which trauma patients may benefit from routine surveillance.14,39 Weekly duplex scanning may be particularly beneficial in high VTE risk patients who cannot be started or maintained on pharmacologic prophylaxis. Whatever the institutional guidelines, identification of DVT should not be a hospital-reported outcome. Institutions that routinely screen all trauma patients have higher rates of DVT, and those centers with comprehensive quality improvement efforts that do not routinely screen will also have higher DVT rates because of a lower threshold for ordering a venous compression duplex. G Pharmacologic prophylaxis must be initiated as soon as possible and for most trauma patients may be initiated within 24 hours. When high VTE risk trauma patients who receive enoxaparin within 24 hours of admission are compared with those who receive only mechanical prophylaxis, minor and major bleeding events do not differ.40 As detailed in section E, appropriate delays may occur in the initiation of pharmacologic prophylaxis because of active bleeding, coagulopathy, hemodynamic instability, solid organ injury, TBI, or spinal trauma. In most cases, pharmacologic prophylaxis may be started in less than 24 hours, and in almost every case, pharmacologic prophylaxis may be started in less than 72 hours. Pharmacologic prophylaxis is often held because of pending surgery despite the evidence that it may be initiated before most surgical procedures.4,41–43 Trauma patients who require an operation are unique in that their first operation may occur within minutes of arrival or days into the hospitalization. Increasingly, pharmacologic prophylaxis is delayed or skipped for pending surgery, which leads to an increased VTE rate.40 Preoperative dosing of pharmacologic prophylaxis is not unique to trauma. In other patient populations at high risk for VTE, the use of preoperative pharmacologic prophylaxis decreased the DVT rate without increasing the complication rate.41,42 Guidelines for perioperative care in gynecologic/oncology recommend, "Prophylaxis should be initiated pre-operatively and continued post-operatively."44 Patients who underwent elective hip surgery who received low molecular weight heparin approximately 6 hours before surgery had a lower rate of proximal DVT without increasing major, minor, or trivial bleeding rates.43 This benefit was not observed when low molecular weight heparin was provided 12 hours or more preoperatively.43 We believe that the common and somewhat reflexive process of withholding pharmacologic prophylaxis for 12 to 24 hours before planned surgical procedures is almost always unnecessary and will result in an increased VTE risk without an accompanying decrease in the risk of bleeding events. H After deciding to start pharmacologic prophylaxis, the specific anticoagulant and initial dose should be determined for each patient. Enoxaparin is the recommended choice for most trauma patients with higher doses considered the of The for pharmacologic prophylaxis is the low molecular weight heparin enoxaparin because of increased longer and more and compared with unfractionated Enoxaparin less with which may reduce bleeding complications compared with unfractionated a lower incidence of and does not have the associated observed with heparin When the initial mg of enoxaparin twice daily should be considered the for most trauma patients, as 30 mg twice daily frequently results in pharmacologic patients 18 to years with weight of more than and a creatinine of more than should be started on mg of enoxaparin twice as this dose is safe and the VTE Patients who are older than less than or who have a creatinine of 30 to should to receive initial dosing at 30 mg of enoxaparin twice The initial enoxaparin dose for trauma patients with a may also be based on twice twice or 30 mg for to patients, mg for to patients, and mg for patients greater than Patients who are initiated on higher doses of enoxaparin based weight should be by because of the in creatinine after trauma that lead to in the enoxaparin Although enoxaparin is to heparin for pharmacologic prophylaxis, institutions to dose unfractionated heparin at 5,000 U three daily based in part on a randomized that that this be and compared with 30 mg of enoxaparin twice This practice should be as the was because of an DVT rate of for unfractionated heparin for enoxaparin, and a 10% for the The difference in the VTE rate was which enoxaparin without vs. enoxaparin, p = In the study was not to a difference in the rate of PE or both of which the complication rate and care More 30 mg of enoxaparin twice daily was established as superior to U of unfractionated heparin three daily at the prevention of VTE and for Quantifying the risk and benefit of the type and initial dose of pharmacologic prophylaxis for each patient is a challenge best determined by the trauma team at bedside. As mg of enoxaparin twice daily is the recommended initial pharmacologic prophylaxis for most trauma patients. Detailing every indication where an therapeutic or dose may be indicated is outside the scope of these guidelines; several are described below. In the presence of or a creatinine of subcutaneous unfractionated heparin at U every 8 hours may be Because enoxaparin is by the to patients with failure may lead to increased bleeding complications and should be Enoxaparin not and for use in patients. lower enoxaparin doses in the setting of a creatinine of may be possible in the but is necessary before this can be In most other enoxaparin is to unfractionated as enoxaparin leads to lower VTE rates without increased bleeding Brain and Trauma For TBI patients, enoxaparin is associated with less VTE and higher than unfractionated heparin with no difference in the progression of brain regardless if the dose was in less than 24 hours after 24 to 48 hours, or after 48 Similarly, those patients with spine trauma should receive early Patients with brain and spine trauma should be initiated on 30 mg of enoxaparin twice daily and considered for dose by Patients patients require specific dose recommendations for pharmacologic prophylaxis after trauma because of the as as the increase in and weight that occur the of require higher enoxaparin doses with more unfractionated heparin enoxaparin the and both are considered safe to use in As during an admission for trauma, patients should receive 30 mg of enoxaparin twice daily by a of to or a of to For patients who more than initiating mg of enoxaparin twice daily is recommended with similar and Pharmacologic prophylaxis with or aspirin should not be a choice for pharmacologic prophylaxis for most trauma patients because of the of related clinical The use of or aspirin may be considered in the setting of injuries, but only if the patient injection with enoxaparin or unfractionated are for pharmacologic prophylaxis after elective surgery, 10 mg of and mg of twice both which are trials that or to enoxaparin demonstrate that have to better VTE rates with similar to higher bleeding In contrast, other that enoxaparin a lower VTE and a lower bleeding Because only retrospective have the use of for pharmacologic prophylaxis after trauma, randomized trials are necessary before a for trauma The use of low dose aspirin may also be considered for pharmacologic prophylaxis in trauma patients with injuries who For those trauma patients started on a for pharmacologic prophylaxis, aspirin may replace the after days with similar prevention of I trauma patients require dose after initiating Because of the in and enoxaparin by is In one of trauma patients required doses of mg or and required doses of mg or enoxaparin by or to lower the VTE rate without increasing bleeding complications in moderate to severely injured patients, trauma patients who require injuries, and surgical Although debate on the appropriate for suggests to for or to for should also be considered for those patients who receive Although not for pharmacologic prophylaxis, with platelet may assist with platelet A randomized that used as an to identify enoxaparin doses did not lower rates of VTE with the enoxaparin In contrast, with platelet may help if a hypercoagulability is due to platelet which encourages the addition of aspirin to the pharmacologic prophylaxis aspirin is the initial recommended dose is mg daily with the of increasing the dose to mg daily on with platelet The uninterrupted dosing of pharmacologic prophylaxis should be the for most trauma patients their hospital Although the and benefit of uninterrupted pharmacologic prophylaxis were established more than of trauma patients A is observed the number of doses and DVT risk such that patients who to doses have higher DVT risk compared with those with no For TBI patients who are started on pharmacologic prophylaxis, dosing an approximately increase in the VTE The following are common reasons for pharmacologic pending procedure patient was from the for bleeding epidural and When holding pharmacologic prophylaxis, the rate of bleeding with pharmacologic prophylaxis is no than without VTE events are compared with bleeding complications, the pharmacologic should focus on pharmacologic prophylaxis without The appropriate for holding or pharmacologic prophylaxis acute spinal surgery, epidural or and these are below. Although routine VTE surveillance is not indicated for all trauma duplex scanning may be in those at high VTE venous compression duplex should be performed for symptomatic evidence of DVT such as or For those trauma patients with injuries and in pharmacologic prophylaxis, venous compression duplex may be a DVT or PE is then therapeutic is necessary per guidelines, and if it is then an should be considered as detailed in section Surgery As in section routinely holding pharmacologic prophylaxis because of pending surgery is only with few for brain or spine Given the delays and of that may occur during trauma patient holding pharmacologic prophylaxis preoperatively can days of pharmacologic prophylaxis. Preoperative pharmacologic prophylaxis is safe for trauma and leads to a lower VTE The preoperative of pharmacologic prophylaxis is also encouraged for surgical patients in other who have a high VTE risk and leads to a lower DVT rate without increasing the complication The lower VTE rate is if pharmacologic prophylaxis is provided more than 12 hours preoperatively.43 reduce morbidity and in trauma patients injuries and are often a component of pain Patients who require an epidural have in pharmacologic such that epidural is associated with an increased VTE whereas previously this was not the Guidelines a enoxaparin dose and epidural by a to before enoxaparin is at 10 and 10 the dose may be held for 10 epidural to allow for the necessary without prophylaxis. 10 the enoxaparin dosing may only one dose is higher doses of enoxaparin are required for pharmacologic prophylaxis, Guidelines a for therapeutic enoxaparin before epidural by a to before at doses of enoxaparin should be for any enoxaparin enoxaparin doses are encouraged with to the higher VTE rate associated with epidural For unfractionated a to is recommended before epidural by a before unfractionated heparin is which for uninterrupted platelet should be considered for those trauma patients who receive pharmacologic prophylaxis because of the risk of is recommended for patients who are considered high risk for approximately every 3 days from day to day or until pharmacologic prophylaxis is Trauma patients who are only to enoxaparin may be considered low risk for and may not require routine platelet as the rate of clinical was with heparin compared with with The clinical diagnosis of may be by that thrombosis, and the heparin must be with such as the which can for trauma patients for because of the of these and the with dosing and their therapeutic may be considered in the setting of proximal DVT or PE when there is a contraindication to appropriate therapeutic The use of is among trauma centers although their is decreasing without a in PE is not In a randomized of high VTE risk trauma patients who were to receive pharmacologic prophylaxis during the first 72 hours of a did not lower the incidence of PE or which established the of of early of an in this The of an does not regardless of whether a DVT is or guidelines provide recommendations and most studies have among patients diagnosed with an acute proximal DVT or PE who cannot receive therapeutic an should be considered to reduce the rate of PE without the Trauma patients with TBI, or spine injuries, and those who undergo major surgery are at VTE risk and should be considered for pharmacologic prophylaxis. Pharmacologic prophylaxis after for high VTE risk trauma patients is by evidence that demonstrates the practice is safe, and and may be considered for patients with TBI, or spine injuries, and those who undergo major The VTE risk occurs during the first 3 after injury with approximately required until the VTE rate to that of the general Venous for of trauma at a cost of pharmacologic prophylaxis with enoxaparin is associated with a low rate of clinically relevant bleeding complications, and is in patients at high VTE The of pharmacologic prophylaxis following or pelvic surgery for or was associated with a decrease in VTE Because the optimal dose and of enoxaparin after trauma are not doses more than 30 mg twice daily should be and the of pharmacologic prophylaxis may be considered for to after the of For those who undergo major surgery, pharmacologic prophylaxis may be to days from the of may be initiated for pharmacologic prophylaxis for high VTE risk trauma patients, as it shown to be as as enoxaparin with less bleeding complications and better and is not by the of may also be considered for pharmacologic prophylaxis after This algorithm was designed to provide comprehensive and guidance at reducing the VTE rate after trauma. Although there are multiple factors that will lead to from the most trauma patients should be initiated on early and higher doses of enoxaparin that often should be by For most trauma patients, pharmacologic prophylaxis should uninterrupted the hospital and at after preventable and delays to the initiation and doses of pharmacologic prophylaxis should be a focus of all trauma and it associated with decreased rates of VTE events.

Venous Duplex Scanning in the Diagnosis and Treatment of Progressive Superficial Thrombophlebitis

1. The forearm perfusion technique was used to study the effect of intra-arterial injections of ethanol with or without digoxin on the metabolism and electrolyte flux of forearm tissues in normal male volunteers. 2. In six subjects infusion of ethanol alone (2·9 mg/min over 30 min) resulted in no alterations of forearm blood flow, O2 consumption, carbohydrate metabolism, or flux of potassium and calcium. Although there was no change in extraction of [14C]oleic acid, a significant net output of oleic and total free fatty acids was observed from both deep venous and superficial venous systems. 3. In six subjects the intra-arterial infusion of [3H]digoxin (0·09 μg/min with ethanol, 2·9 mg/min over 30 min) resulted in no alteration of forearm blood flow. During the steady state achieved after 5–8 min of perfusion, 50·3% of the calculated local arterial plasma digoxin concentration of 2·73 μg/l was extracted by the deep venous system with a significant increase in glucose extraction. The respiratory quotient and fractional utilization of O2 by glucose increased. No change in extraction of [14C]oleic acid from arterial blood was observed. However, the net output of oleic and total free acids from both deep and superficial venous systems was insignificant in comparison with that observed in the ethanol control subjects. The changes in K+ flux were similar to those noted in the ethanol group. In the post-digoxin period there was a significantly increased uptake of Ca2+ by forearm tissues. 4. This is the first demonstration of the stimulatory effects of digoxin on glucose metabolism, the antilipolytic effects of this drug and its effect on Ca2+ fluxes in vivo in man.

Six hundred forty-four legs were examined by means of descending venography in patients with chronic venous insufficiency. Three patient positions (supine, 30 degrees semierect, and 60 degrees semierect) were used with a standard angiographic technique. Patients were also studied during either normal respiration or a Valsalva maneuver. The deep venous valvular system was incompetent more often than the superficial (saphenous) venous system. Positive venograms revealed that reflux occurred into the deep venous system alone in 82%, the superficial venous system alone in only 2%, and a combination of deep and superficial systems in 16%. The authors conclude that descending venography is best performed at the more physiologic 60 degrees semierect position and with the Valsalva maneuver, which enables evaluation of the competence of valves in the closed position.

Fat necrosis is a common complication for the deep inferior epigastric perforator (DIEP) flap. A thorough understanding of the factors associated with fat necrosis will aid operative planning for reconstructive surgeons. A systematic review of the literature was performed between January 1989 and April 2019. Studies were included if they reported on fat necrosis in DIEP flap or evaluated the perfusion of the DIEP flap. Twenty-eight out of 312 studies met the inclusion and exclusion criteria. Fat necrosis rates ranged from 12.0 to 45.0% on clinical examination within the literature. The four main perforator-specific factors identified included perforator perfusion zones, perforator location, perforator number and venous congestion. Medial row perforators have a wider perfusion zone, while lateral row perforators have a narrow perfusion zone. Holm zone III has a higher rate of fat necrosis compared to Holm zone II. One to two perforators and more than five perforators and a Type III atypical connection between the superficial and deep venous system had a higher rate of fat necrosis. The DIEP flap should incorporate between two and three perforators of a substantial calibre; Holm zone III should be excluded if able and careful review of the pre-operative imaging should be performed to analyse the connections between the deep and superficial venous system. There are multiple perfusion-related factors to consider when planning the DIEP flap and ultimately a patient-specific approach to the vascular anatomy is essential. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Clinicians should be aware of the occurrence of deep vein thrombosis following brown recluse spider bite.

A 48 year old female had enrolled herself in a project on post prophylaxis of deep vein thrombosis. The project involved administration of intravenous antithromboltic drug in patients undergoing major abdominal surgery lasting more than 45 min under general anesthesia. She had been operated for carcinoma ascending colon. She had no complaints of lower limb pain, ulcer, claudication or swelling. However on examination there were prominent reticular veins over both thighs. On the eighth postoperative day conventional venography of both lower limbs was done after obtaining informed consent and ensuring a normal renal function test. Nonionic contrast (Ultravist 300, Schering AG, Berlin, Germany) was injected in each lower limb in the proximal part of the great saphenous vein just below the ankle joint after applying a tourniquet just above the ankle joint. Serial radiographs of different parts in various views were taken on a computerized radiography system (Kodak Direct View Elite CR System). During analysis of the venogram we found that the deep venous systems were normal in course and caliber. No evidence of deep vein thrombosis was present. Superficial venous systems were opacified simultaneously despite placement of tourniquet at appropriate sites with adequate applied pressure. There was absence of venous valves in the perforators and deep and superficial venous systems in both lower limbs (Fig. 2a and b). A color Doppler study was done (GE Logic P5) which showed reflux into the superficial venous system during mild Valsalva maneuver. The perforators were incompetent and mildly dilated with lack of venous valves in superficial and deep venous systems in both lower limbs (Fig. 3a and b). The other Doppler indices including velocity, color filling and wave form pattern were normal in both lower limbs. The venous systems of the lower limb are provided with pocket –shaped formations called valves. These are generally bicuspid, rarely tricuspid extraversions of endothelium and tunica media with muscle bundles connected at the valve base to provide support to the venous walls so that they can withstand gravitational pressure of the venous blood column. The numbers of valves in superficial and deep systems decrease progressively from distal to proximal regions and they are rarely seen in the caval vein (Fig. 1a and b). Common congenital venous anomalies like aplasia/hypoplasia and avalvulia are the result of the developmental arrest of later stages of vascular trunk formation during early fetal growth. Embryologically these lesions are also known as “post-truncal fetal lesions”. Truncal lesions are further subdivided into obstruction, aplasia or hypoplasia [1–8]. Avalvulia or absence of valves is severe form of hypoplasia that produces venous reflux. Avalvulia is a common finding in KlippelTrenaunay syndrome. There is no age or sex predilection. Diagnosis is made by one or more of the following methods: color doppler imaging, plethysmography, contrast enhanced computed tomography, magnetic resonance venography and conventional or digital venography. Knowledge of integrity of deep venous system is mandatory because of the many venous interventional M. Kumar (*) : R. Singh Department of Radiodiagnosis, King George’s Medical University Lucknow, Uttarpradesh, India PIN-226003 e-mail: docmdeo@gmail.com

75-Year-Old Woman With Chest Pain and Shortness of Breath

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems. The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient. The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%. All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems. The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient. The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%. All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.

Appropriate venous thromboembolism (VTE) chemoprophylaxis in trauma and emergency general surgery (EGS) patients is crucial. The purpose of this study is to review the recent literature and offer recommendations for VTE chemoprophylaxis in trauma and EGS patients. We conducted a literature search from 2000 to 2021 for articles investigating VTE chemoprophylaxis in adult trauma and EGS patients. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Our search resulted in 34 articles. Most studies showed low-molecular-weight heparin (LMWH) is similar to unfractionated heparin (UFH) for VTE prevention; however, LMWH was more commonly used. Adjusted chemoprophylaxis dosing did not change the VTE rate but the timing did. Direct oral anticoagulants (DOACs) have been shown to be safe and effective in trauma and traumatic brain injury (TBI)/spinal cord injury (SCI). Studies showed VTE prophylaxis in EGS can be inconsistent and improves with guidelines that lower VTE events. There may be no benefit to receiving LMWH over UFH in trauma patients. In addition, different drugs under the class of LMWH do not change the incidence of VTE. Adjusted dosing of enoxaparin does not seem to affect VTE incidence. The use of DOACs in the trauma TBI and SCI setting has been shown to be safe and effective in reducing VTE. One important consideration with VTE prophylaxis may be the timing of prophylaxis initiation, specifically as it relates to TBI, with a higher likelihood of developing VTE as time progresses. EGS patients are at a high risk of VTE. Improved compliance with clinical guidelines in this population is correlated with decreased thrombotic events.

Prevalence of various congenital vascular malformations in patients with Klippel-Trenaunay syndrome.

Asymptomatic deep vein thrombosis in critically ill COVID-19 patients despite therapeutic levels of anti-Xa activity

Medication in venous disorders is different for the superficial and deep venous systems. This is because of the different pathologies of the two systems. Furthermore, when treating thrombosis, a distinction should be made between the superficial and deep venous system. Also for the deep venous system, one should make the distinction between acute and past venous thromboembolism (VTE), treating recurrent VTE, and for how long to continue treatment. Bridging therapy is a new chapter that has been addressed the last decade. Pharmacological treatment, complementary to compression therapy in venous ulcers, is discussed. In this chapter a detailed summary of the main studies on VTE treatment and prophylaxis with their conclusions is provided for ease of reference. The new oral anticoagulants are presented in the context of both treatment and prophylaxis, and their safety is discussed. Glossary of Terms (Eklof et al. 2009) Chronic venous disorder This term includes the full spectrum of morphological and functional abnormalities of the venous system. Chronic venous disease (Any) morphological and functional abnormalities of the venous system of long duration manifested by symptoms and/or signs indicating the need for investigation and/or care. Chronic venous insufficiency (C3–C6) A term reserved for advanced CVD, which is applied to functional abnormalities of the venous system producing edema, skin changes, or venous ulcers.