Outflow fraction is the fractional part of the total venous volume that is expelled 1 second after elevating the limb. 10, 11 Venous volume is the total venous volume of the measured limb and is calculated while the patient is standing. Air plethysmography is a method of measuring absolute limb blood volume changes, and consists of an air chamber that, when inflated around the leg, can separately measure venous reflux, calf muscle function, venous obstruction, and venous hypertension ( Figure 1). Finally, air plethysmography (APG) was conducted on both lower extremities. These veins were evaluated for patency, flow characteristics during respirations (phasicity), flow characteristics independent of respirations (spontaneity), and evidence of chronic venous obstruction. Color flow duplex ultrasound examinations of both legs included the external iliac, long saphenous, femoral (common, deep and superficial), politeal, tibioperoneal, and calf perforating veins. Patients with a history of venous injury underwent color flow duplex ultrasound imaging (CFD) (model 128XP, Acuson Inc, Mountain View, Calif) performed by a registered vascular technician. A physical examination of the lower extremities noted any evidence of varicose veins, ankle or leg edema, skin irritation, pigment changes, and/or ulceration. After obtaining informed consent from these eligible patients and reviewing their medical record, the study investigators interviewed participating patients regarding any symptoms of venous insufficiency (ie, pain, edema, limb heaviness, skin changes) and about their physical functions with reference to the time of injury. The remaining patients were encouraged to come to the trauma center for an outpatient evaluation. 9 We excluded patients who were younger than 18 years old, were currently pregnant, had bilateral fasciotomies, had a history of venous disease or elective venous surgery of the lower extremities, and those with pelvic fractures or tumor. All fasciotomies that had been performed in these patients included both medial and lateral fascial releases without fibulectomy, as described by Mubarak and Owen. The study protocol and subject letters were reviewed and approved by the Committee on Human Research at the University of California, San Francisco. These patients were initially contacted by formatted letters sent to their last known addresses, and they were asked to send reply cards if they were willing to participate in the study that we described. Patients who had been admitted to our trauma center during a 9-year period (1988-1996) with vascular, orthopedic, or soft tissue injuries requiring fasciotomy were identified through the trauma registry. These patients are at risk for the long-term development of chronic venous insufficiency following lower extremity trauma. There were no differences in APG variables between patients with vascular injuries vs those with orthopedic or soft tissue injuries.Ĭonclusions Lower extremity fasciotomy impairs long-term calf muscle pump function, as measured by APG, in patients with and without vascular injuries. There were no significant changes in venous filling index, a measure of venous reflux, or in outflow fraction, which correlates with venous obstruction. The APG data showed significant mean differences between fasciotomy and control extremities in ejection fraction ( P<.001) and residual volume fraction ( P<.001), both measures of calf muscle pump function. Eight patients had signs or symptoms of venous insufficiency, the severity of which appeared to be time dependent. The time from injury to examination ranged from 5 months to 20 years. Results Seventeen patients completed the study, including 8 with a history of vascular injuries, 6 with old fractures, and 3 who had undergone fasciotomy for soft tissue infections. Main Outcome Measures Function of the calf muscle pump as measured by APG, and evidence of chronic venous insufficiency as measured by APG, findings on clinical examination, and by venous ultrasonography. Patients with a history of venous injuries were also studied with color flow duplex venous imaging. Interventions Participating patients completed a study questionnaire, and then underwent a complete vascular examination, including air plethysmographic (APG) assessment. Patients Seventeen of the 83 patients identified through trauma, vascular, and/or orthopedic registries consented to participation in this study. Objective To test the hypothesis that fasciotomy may impair the function of the calf muscle pump, which in turn could result in the development of chronic venous insufficiency.ĭesign A cohort study of patients with a history of lower extremity fasciotomy. Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.
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