Vascular laboratory personnel on-call: effect on patient management.

PURPOSE: A prospective study was undertaken of all vascular laboratory tests performed by the "on-call" technologist during a 3-year time period. METHODS: Technologists take call on a rotating basis. All patients evaluated had symptoms. History and risk factor data were collected at the time of patient encounter. RESULTS: Studies were initiated from the emergency department 56% of the time, from inpatient examinations 33% of the time, and from outpatient examinations 11% of the time. Ninety percent (n = 440) of the studies obtained were venous duplex scans (VDS). Fifty-eight percent (257 of 440) of the studies were performed on weekends. Thirty-two percent of the studies resulted in admission of the patient. Of the 440 VDS obtained, 51% (224 of 440) identified some type of disease. Acute deep venous thrombosis (DVT) was diagnosed in 15% (67 of 440), acute superficial venous thrombosis (SVT) in 4% (17 of 440), acute DVT and SVT in 7% (31 of 440), chronic DVT in 4% (17 of 440), chronic SVT in 4% (16 of 440), and chronic DVT and SVT in 1% (3 of 440); 2% (9 of 440) of the DVTs were of indeterminate age. Other diseases were identified in 22% (95 of 440), including popliteal cysts, inguinal lymphadenopathy, and soft tissue edema. CONCLUSIONS: Having an "on-call" vascular technologist has allowed patients with acute venous thrombosis to be triaged and admitted, if necessary, in a timely fashion. Those patients who have symptoms and a negative VDS result are able to avoid unnecessary hospitalization and treatment. The expense of this service is easily justified by the savings of unnecessary hospital days.

Allastair B. Karmody Award. Calf vein thrombi are not a benign finding.

BACKGROUND: Currently, there is no consensus in the literature regarding which patients with calf vein thrombi are at high risk for proximal propagation. This study examined patients with isolated calf vein thrombi with serial duplex scans in order to identify risk factors that would predict outcome. PATIENTS AND METHODS: Between May 1989 and November 1994, 288 patients were identified with isolated calf vein thrombi. One hundred ninety-two of them had sequential scans performed. RESULTS: Fifty-three (28%) of the 192 patients had propagation of their initial thrombi. The most proximal level of propagation was the popliteal vein in 11 patients, the superficial femoral vein in 5, the common femoral vein in 5, adjacent tibial or soleal veins in 24, adjacent soleal veins alone in 7, and the lesser saphenous vein in 1. Three patients whose thrombi propagated had free-floating thrombus tips in the large veins of their thighs. Symptoms, prophylaxis, and risk factor analysis comparing those patients whose thrombi propagated to those whose thrombi did not found no statistically significant prognostic value. Single or multiple calf vein thrombi did not predict propagation. Of the 23 patients treated with heparin, only 3 had thrombus propagation. None of these reached the level of the knee (including popliteal vein). CONCLUSIONS: The natural history of distal lower extremity thrombosis does not appear to be as benign as previously believed.

Does the asymptomatic limb harbor deep venous thrombosis?

Deep venous thrombosis (DVT) is a great masquerader that cannot be reliably predicted by a patient's symptoms, history, or risk factors. Bilateral lower extremity duplex ultrasonography scans were made of 2,511 patients and analyzed to identify, if possible, a population in which a unilateral study would be appropriate. A total of 1,086 (43%) patients were found to have deep venous thrombosis--742 (30%) unilateral and 344 (14%) bilateral. Of the patients with DVT for whom side-of-symptom information was recorded, 64% had symptoms referable to the involved extremity and 36% had symptoms referable to the contralateral extremity. Of the 362 patients who had asymptomatic lower extremities, 128 (35%) had DVT. Moreover, clots were found in asymptomatic limbs in an additional 263 patients whose contralateral limb was symptomatic. Logistic regression analysis did not reveal combinations of symptoms and risk factors that could predict DVT. If DVT is suspected, the patient should undergo bilateral lower extremity duplex scanning.

The correlation between anterior-posterior translation and cross-sectional area of anterior cruciate ligament reconstructions.

Total anterior-posterior translation is commonly used to assess the integrity of the cruciate ligaments and the success of reconstructive surgery. The purpose of this study was to determine, after surgical reconstruction of the anterior cruciate ligament with a biological graft, if total anterior-posterior translation correlated with graft length, cross-sectional area, or mechanical properties. These factors were investigated by analyzing data from three previous studies. These studies involved replacement of the anterior cruciate ligament in cynomolgus monkeys and goats, with free and vascularized patellar tendon autografts and both patellar tendon and anterior cruciate ligament allografts. Data were available at time periods of 6 and 12 months after surgery. We found statistically significant inverse correlations between the amount of anterior-posterior translation and cross-sectional area of a graft at the time of sacrifice. The Pearson correlation coefficients ranged from -0.966 (p < 0.002) to -0.830 (p < 0.05). We hypothesize that these correlations result from the following mechanism: the increased anterior translation reflects a slack graft; a slack graft is stress shielded by other structures about the knee; the reduced in vivo stresses on the graft modulate cellular metabolism in a way that over time produces a small cross-sectional area.

The diagnosis of knee motion limits, subluxations, and ligament injury.

The clinical diagnosis of knee ligament injuries requires the clinician to: 1) estimate the abnormal motion limits that occur in one or more of the six degrees of freedom that comprise three-dimensional motion; 2) determine the abnormal position (subluxation) of the medial and lateral tibiofemoral compartments; and 3) precisely define the anatomical structures injured and degree of that injury. To determine the clinician's ability to perform these tasks, we evaluated 11 knee surgeons' clinical examination for knee instability. The positions and motions included were measured in right-left cadaveric knees by a three-dimensional instrumented spacial linkage. We compared the clinicians' estimate of knee motion limits and subluxations with the actual measured values. Before and after the clinicians' examination, the three-dimensional limits of knee motion were measured in the knees in the laboratory under defined loading conditions. Also, in one knee, the ACL and superficial medial collateral ligament were cut and the examiners, none of whom were informed of the sectioning, were asked to arrive at a diagnosis. The results for all of the clinical instability tests were similar. There was wide variability between examiners in the starting position of knee flexion and tibial rotation and in the amount of tibial translation and rotation induced. Although some examiners displaced the knee to the maximal displacement limits obtained in the laboratory, others did not, by a substantial margin. This suggests a wide variation in the loads applied by examiners to the knee joint during the tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Upper extremity venous thrombosis diagnosed by duplex scanning.

The incidence of axillary-subclavian venous thrombosis continues to rise, while reports of noninvasive methods to diagnose this condition have been sparse. A review of the records of 693 consecutive upper extremity duplex scans was performed, and a diagnosis of acute venous thrombosis was made in 123 of these patients. Of these, 85 involved the axillary or subclavian vein. Use of a central venous catheter was the most common risk factor for axillary-subclavian venous thrombosis. Within this group, 8% had a pulmonary embolism, of which 25% were fatal. Follow-up of patients with axillary-subclavian venous thrombosis at a mean of 2 years revealed that 49% of these patients had died. Of the remaining patients, more than one third had evidence of the post-thrombotic syndrome. Duplex scanning of the venous system provides a safe, reliable, and repeatable method of evaluating and following patients with suspected venous thrombosis of the upper extremity.