Emergency Vascular Surgery A Practical Guide - part 9 ppsx

160 Chapter 13 incidence varies with the population studied and increases with age Hospital-based studies present a larger proportion of pulmonary embolism (PE), whereas community cohorts have more thrombosis patients Manifestations range from a superficial thrombophlebitis or a minor deep venous thrombosis (DVT) that produces only minute symptoms to a DVT with massive embolism to the lungs, threatening the patient’s life While open surgical treatment of venous thromboembolic disease is rarely indicated, it is helpful to have basic knowledge about diagnosis, pathogenesis, and anticoagulation treatment This is important for differential diagnosis and for the few instances when emergency endovascular or open surgical treatment is indicated This chapter will also describe the technique for surgical and endovascular treatment of acute DVT 13.2.2 Pathogenesis When DVT occurs, clots have usually formed in the small deep veins in the calf Patients afflicted have hypercoagulative disorders, are taking medications that affect clotting that make them susceptible to venous thrombosis, has malignancy or has been immobilized for a larger period The clot causes a local inflammation in the venous wall and adjacent tissue that may make the calf tender Because the small veins in the calf are paired, the clot does not cause significant venous obstruction or distal edema Flow in the obstructed vein will decrease, however, which increases the risk for continuing clot formation The clot will then grow in a proximal direction and continue to obstruct more veins Also at this stage distal edema is quite uncommon because collateral flow is extensive in the legs, and significant swelling does not occur until the common femoral vein is obstructed At this level the outflow from the deep femoral, superficial, and great saphenous vein is affected Continued obstruction, causing near occlusion of all the main veins in the leg and pelvis, can lead to a dreaded condition called phlegmasia cerulea dolens (discussed later) Any time during this process there is also a substantial risk that clots will dislodge from the leg veins, follow the blood flow to the lungs, and cause PE Acute Venous Problems Primary iliac vein thrombosis occurs most commonly on the left side where a stenosis frequently is a predisposing factor 13.3 Clinical Presentation Patients with DVT experience pain and leg swelling that often is worse when standing or walking Some patients also feel warmth and notice that the leg is red Patients with caval obstruction have bilateral symptoms These examples constitute the classic symptoms of DVT, but many patients not have any symptoms at all and present with PE only Signs of this condition include shortness of breath and chest pain that may be worsened by deep breaths Occasionally, patients also report that they have been coughing up phlegm that may be tinged with blood Patients with phlegmasia cerulea dolens have similar but more severe symptoms Discoloration is often pronounced Pedal pulses are usually absent, and the leg is very tender Foot gangrene is also noted occasionally It may therefore be mistaken for arterial embolism, but misdiagnosis can be avoided by remembering that acute arterial occlusion does not cause edema Physical examination is only 30% accurate for DVT and a poor way to establish the diagnosis The most common finding, however, is localized calf tenderness Homan’s sign – pain when dorsiflexing the foot with the knee extended – is neither sensitive nor specific and should probably not be used Other examination findings are visible superficial collateral veins, pitting edema, and swelling of the entire leg To be significant, the latter should expand the calf circumference by more than cm compared with the other leg Patients with primary iliac vein thrombosis may present with abdominal pain in the lower quadrant, tenderness over the vascular bundle in the groin and general swelling of the leg Patients with upper limb thrombosis have similar symptoms; the most common are arm swelling and discoloration or pain Scoring systems combining clinical findings and medical history have been proposed to increase accuracy of the examination If the examination is positive for more than three of the signs and symptoms described above, up to 75% of the 13.5 Management and Treatment patients have evidence of DVT as diagnosed by duplex examination 13.4 Diagnostics All patients, including those considered to have only small risk to be suffering from DVT and those having arm symptoms, should undergo duplex scanning or perhaps phlebography The duplex examination includes visualization of the veins, clots, blood flow, and vein compressibility The latter is considered a direct test of DVT because a vein with clot cannot be compressed, whereas the walls of a healthy vein are very easy to squeeze together by pressure with the probe Lack of blood flow variation with breathing is another sign suggesting DVT on duplex examination Phlebography includes cannulating a superficial foot vein and injecting contrast during fluoroscopy to enable visualization of thrombosed veins This method was the standard diagnostic procedure before duplex appeared as the primary choice for establishing the DVT diagnosis Today it is used mostly when duplex is unavailable in the hospital or when it is unable to identify the deep leg veins Another test useful for DVT diagnosis is determining the concentration of the fibrin degradation product D-dimer in the blood This test has a sensitivity for DVT of 90% or greater as well as a negative predictive value of 90% or greater by most studies Accordingly, a negative D-dimer level (the cut-off level depends on the type of assay used) in a symptomatic patient with a clinically suspected diagnosis nearly provides exclusion of DVT Therefore, it is suitable as a screening test before further work-up when the diagnosis is not obvious tals this means starting with duplex scanning to establish the diagnosis If signs of DVT are present, it is important to elucidate the extent of thrombosis during the examination This information is useful in the management process because some patients with femoral vein, iliac vein, or cava thrombosis may need thrombolysis or even a cava filter When the DVT diagnosis is confirmed, baseline blood coagulation parameters are obtained, and low molecular weight heparin treatment is initiated It is also important to exclude other diagnoses that could contribute to the thrombosis formation For example, clinical indications of an intraabdominal malignancy could be confirmed or eliminated by computed tomography (CT) Both inpatient and outpatient protocols can then be used for the continued treatment of the patients (No further recommendations will be given on the medical management of DVT here because this book is intended to focus on vascular surgical treatment.) Few diagnosed patients are candidates for urgent surgical or endovascular treatment, but the most common situations when it can be considered are listed in Table 13.2 Patients with upper limb thrombosis may also benefit from urgent thrombolysis The same clinical findings listed in the table are also applicable in patients with duplex-verified axillary or subclavian vein thrombosis If D-dimer is positive and pulmonary symptoms are prominent in the medical history (or the Table 13.2 Clinical findings indicating that open surgical or endovascular treatment should be considered in patients with duplex-verified thrombosis into femoral and/or iliac veins Clinical findings Treatment type(s) 13.5 Management and Treatment Young age Thrombolysis 13.5.1 In the Emergency Department Duration of symptoms