Is above knee bypass defunct?

As endovascular treatments improve, the inevitable progress will result in the abandonment of conventional bypasses. First and foremost in this regard is the use of above knee bypass, particularly with prosthetic graft material. Already, endovascular success approaches or exceeds the patency seen with this bypass technique. As a result, in centers with endovascular expertise in infrainguinal intervention, bypass surgery is increasingly being replaced by these techniques and conventional bypass surgery is disappearing. Over the next few years, above knee bypass will be replaced by endovascular techniques in most centers as our results with these techniques improve.

Is ultrasound more accurate than axial computed tomography for determination of maximal abdominal aortic aneurysm diameter?

OBJECTIVE(S): Clinical assessment of maximal abdominal aortic aneurysm (AAA) diameter assumes clinical equivalency between ultrasound (US) and axial computed tomography (CT). Three-dimensional (3D) CT reconstruction allows for the assessment of AAA in the orthogonal plane and avoids oblique cuts due to AAA angulation. This study was undertaken to compare maximal AAA diameter by US, axial CT, and orthogonal CT, and to assess the effect that AAA angulation has on each measurement. METHODS: Maximal AAA diameter by US (US(max)), axial CT (axial(max)), and orthogonal CT (orthogonal(max)) along with aortic angulation and minor axis diameters were measured prospectively. Spiral CT data was processed by Medical Media Systems (West Lebanon, NH) to produce computerized axial CT and reformatted orthogonal CT images. The US technologists were blinded to all CT results and vice versa. RESULTS: Thirty-eight patients were analyzed. Mean axial(max) (58.0 mm) was significantly larger (P<0.05) than US(max) (53.9 mm) or orthogonal(max) (54.7 mm). The difference between US(max) and orthogonal(max) (0.8 mm) was insignificant (P>0.05). When aortic angulation was <==25 degrees, axial(max) (55.3 mm), US(max) (54.3 mm), and orthogonal(max) (54.1 mm) were similar (P>0.05); however, when aortic angulation was >25 degrees, axial(max) (60.1 mm) was significantly larger (P<0.001) than US(max) (53.8 mm) and orthogonal(max) (55.0 mm). The limits of agreement (LOA) between axial(max) and both US(max) and orthogonal(max) was poor and exceeded clinical acceptability (+/-5 mm). The variation between US(max) and orthogonal(max) was minimal with an acceptable LOA of -2.7 to 4.5 mm. CONCLUSION: Compared to axial CT, US is a better approximation of true perpendicular AAA diameter as determined by orthogonal CT. When aortic angulation is greater than 25 degrees axial CT becomes unreliable. However, US measurements are not affected by angulation and agree strongly with orthogonal CT measurements.

Endotension after endovascular aneurysm repair: the Ancure experience.

PURPOSE: The expansion of aneurysms after endovascular repair is a consequence of persistent sac pressure, usually resulting from an endoleak. Several authors have suggested that sac expansion can occur even in the absence of endoleak, referring to this phenomenon as endotension. This study undertakes a review of the largest US endograft trial data to better define the significance of aneurysm expansion in the absence of endoleak. METHODS: The core laboratory imaging database from the Ancure (Guidant) endovascular graft Phase I and Phase II trials approved by the Food and Drug Administration was reviewed with attention to aneurysm size and endoleak. Aneurysm size was measured with standardized two-dimensional computed tomography (CT) scan at the area of largest initial aneurysm diameter. Endoleak was detected with CT scans, color duplex ultrasound scans, and angiography in selected cases. Patients were evaluated at baseline, 3 months, 6 months, 12 months, and every 12 months thereafter. An endograft was classified as leaking if any endoleak was detected with any modality at any time point. RESULTS: A total of 658 patients were entered into these protocols and the data submitted to the core laboratory. A control group of 120 conventional aortic patients and a group of 62 without baseline CT data were excluded from further analysis. Of the remaining 476 patients, 144 (60 tube, 60 bifurcated, and 24 mono-iliac) were free of endoleak at all intervals and had baseline CT measurements to allow comparison. Overall, the average size decrease in this nonleaking group was 9.9 +/- 9.4 mm (range, -50.6-11.1 mm) at a mean follow-up of 23.3 months. Evaluation for overall aneurysm expansion revealed 17 patients who had an increase of 2.3 +/- 2.9 mm (range, 0.3-11.1 mm) at a mean follow-up of 14.1 months. Only two patients without evidence of endoleak exhibited growth of more than 5 mm at maximum follow-up (7.6 mm at 12 months and 11.1 mm at 36 months). Additional analysis of sealed endoleaks and late endoleaks failed to demonstrate any group with expansion in the absence of detectable endoleak. CONCLUSIONS: Endotension appears to be rare in this large series of prospectively evaluated endografts. From this review, endotension seems more likely to represent missed endoleak than true aneurysm expansion in the absence of perigraft flow.

The effect of a venous anastomosis Tyrell vein collar on the primary patency of arteriovenous grafts in patients undergoing hemodialysis.

PURPOSE: Vein collars and patches are used at the distal anastomoses of infrainguinal prosthetic grafts to improve graft patency. We initiated a randomized, prospective study to determine whether a Tyrell vein collar at the venous anastomosis of forearm loop arteriovenous grafts (AVGs) would improve patency. METHODS: Patients who required new forearm AVGs were randomized to (1) a standard end-to-side graft-vein anastomosis (control group) or (2) a Tyrell vein collar between the graft and the vein (study group). End points were (1) graft thrombosis, (2) graft removal and ligation, or (3) inadequate graft function. Randomization of 75 subjects was planned. The study was terminated early for ethical reasons. RESULTS: Seventeen patients (eight men, nine women) with a mean age of 52.8 years (range, 31-79 years) had 17 grafts placed (control group, n = 10; study group, n = 7). Comorbidities were not different between the groups (P>.05). Six (86%) of seven study grafts failed by 9 months (mean, 4.6 months). Four (66%) failed study grafts had venous outflow tract stenosis from intimal hyperplasia. This was confirmed at surgery in three and by angiography in one. The 9-month primary patency was 80% for the control group versus 17% for the study group (P =.015). Smaller outflow vein diameter in the study group (P =. 048) did not account for this inferior graft patency. CONCLUSION: A Tyrell vein collar at the venous anastomosis of a forearm AVG resulted in premature graft failure. The use of a Tyrell vein collar may accelerate venous anastomosis intimal hyperplasia.

Steal syndrome complicating hemodialysis access procedures: can it be predicted?

The development of steal syndrome distal to an arteriovenous fistula (AVF) created for hemodialysis access remains a significant clinical problem. This study was undertaken to determine the role of intraoperative noninvasive testing in the prediction and management of steal syndrome following arteriovenous fistula creation. First, in order to determine a threshold digital/brachial index (DBI) for patients at risk for steal syndrome, we performed a retrospective review of patients who had had the DBI measured and who developed symptoms (steal syndrome) following AVF creation. This was followed by a prospective evaluation of the ability of the DBI to predict which patients undergoing AVF surgery would develop steal syndrome. A DBI of <0.6 identifies a patient at risk for steal syndrome. Intraoperative DBI cannot be used to predict which patient will develop steal syndrome; however, if revision is indicated, the DBI should be increased to >0.6. Failure to accomplish this puts the patient at risk for continued steal syndrome.

Subfascial perforator vein ablation: comparison of open versus endoscopic techniques.

PURPOSE: To compare the outcomes and complications of open (OSPS) versus endoscopic subfascial perforator surgery (SEPS) for treatment of chronic venous insufficiency. METHODS: Data were retrospectively collected on 25 patients who underwent 27 SEPSs from February 1996 to August 1997 and from 22 patients who underwent 29 OSPSs between March 1978 and May 1993. Outcomes were evaluated for postoperative complications, ulcer healing, recurrence, and venous dysfunction scores on the last follow-up for the SEPS group and at 1-year follow-up for the OSPS group. RESULTS: The 2 groups were similar in age, sex, history of previous venous surgery, healed or active ulcers, etiology, deep venous incompetency, pathophysiology, and venous refill times. Eighteen (90%) of 20 active ulcers in the SEPS group healed with recurrences in 5 (28%) limbs at 7.5 +/- 5.4-month follow-up. All 19 ulcers in the OSPS group healed, with recurrences in 13 (68%) limbs at 35 +/- 35-month follow-up. Clinical venous dysfunction scores showed significant improvement following SEPS (10.0 +/- 3.6 to 5.4 +/- 4.1, p < 0.001) and OSPS (10.0 +/- 3.2 to 6.7 +/- 3.6, p < 0.001) with no significant difference between groups. Both groups also had significant improvement in anatomical and disability scores. There was no postoperative mortality in either group. The OSPS group had significantly more wound complications (45%) than the SEPS group (7%) (p < 0.005). The hospital stay and readmission rate for wound problems were also higher in the OSPS group. CONCLUSIONS: The early outcome showed equal improvement in clinical venous dysfunction scores in the 2 groups, but with significantly fewer complications in the SEPS group. Although the long-term durability of the endoscopic approach has not been determined, the short-term results would favor SEPS for treatment of severe venous insufficiency when perforator incompetence is a significant component.

Duplex directed caval filter insertion in multi-trauma and critically ill patients.

This study was undertaken to determine the safety and feasibility of inferior vena cava (IVC) filter insertion at the bedside using duplex imaging in multi-trauma and/or critically ill patients. From February 1996 to August 1997, 53 multi-trauma and/or critically ill patients, who were in the intensive care unit and referred for an IVC filter, were prospectively evaluated for possible duplex directed caval filter (DDCF) insertion. Screening IVC duplex scans were performed in all patients. Satisfactory ultrasound visualization in 46 patients (87%) allowed attempted DDCF insertion. All procedures were percutaneously performed at the bedside using Vena Tech IVC filters. The results from this series showed that DDCF insertion can be safely and rapidly performed at the bedside in multi-trauma or critically ill patients. The procedure is dependent on satisfactory visualization of the IVC by duplex ultrasonography, which was possible in 45 out of 53 (85%) patients. Insertion at the bedside substantially reduces the procedural cost and avoids the need for transport, radiation exposure, and intravenous contrast.

Endoleak after aortic stent graft repair: diagnosis by color duplex ultrasound scan versus computed tomography scan.

PURPOSE: The purpose of this study was to compare the accuracy of a color duplex ultrasound scan (CDU) to a computerized axial tomography scan (CT) in the diagnosis of endoleaks after stent graft repair of abdominal aortic aneurysms. METHODS: The Endovascular Aneurysm Clinical Trial Core Laboratory records were reviewed from 117 concurrent CDU and CT studies that were performed in 79 patients who were implanted with the Endovascular Technologies stent graft device between December 1995 and January 1997. All of the studies were interpreted by the Core Laboratory as having the presence or the absence of an endoleak or as being indeterminate because of technical factors. Of the 117 videotaped CDU studies available for reexamination, 100 were reassessed for technical adequacy on the basis of the following criteria: a satisfactory imaging of the aneurysm sac and of the stent graft with gray scale, and both color and spectral Doppler scan evaluation for endoleak outside the endograft and within the aneurysm sac. RESULTS: Of the 117 studies, 103 CDUs (88%) and 114 CTs (97%) were recorded as having the presence or the absence of an endoleak and 14 CDUs (12%) and 3 CTs (3%) were indeterminate. For the studies that were recorded to have the presence or the absence of an endoleak, the sensitivity, the specificity, the positive and the negative predictive values, and the accuracy of CDUs as compared with CTs were 97%, 74%, 66%, 98%, and 82%, respectively. Of the 100 CDU videotaped studies available for review, the following results were seen: (1) 93 CDUs had satisfactory B-mode images, (2) 76 had satisfactory color Doppler scan images to evaluate for endoleaks, (3) 55 had color Doppler scan assessment of the entire abdominal aortic aneurysm sac for endoleak, and (4) 27 had spectral Doppler scan waveform confirmation of suspected endoleaks. Only 19 CDU studies (19%) with all 4 criteria for complete assessment of endoleak were performed. CONCLUSION: Although most of the CDU studies were technically suboptimal, the CDUs reliably identified endoleaks with an excellent sensitivity and a negative predictive value as compared with CT scans.

A comparison of surgery for neurogenic thoracic outlet syndrome between laborers and nonlaborers.

OBJECTIVE: To determine factors of outcome following surgical intervention for neurologic thoracic outlet syndrome (NTOS). METHODS: In a retrospective study of patients surgically treated for NTOS, outcome was evaluated by postoperative symptoms and the ability of patients to return to work. RESULTS: Good, fair, and poor results were obtained in 26 (48%), 21 (39%), and 7 (13%) patients, respectively. The best predictor of a good outcome was occupation. Nonlaborers were more likely to have good outcome (21 of 32, 66%) when compared with laborers (5 of 22, 23%; P = 0.0025). Only 6 of 20 (30%) laborers were able to return to their original occupation compared with 17 of 26 (65%) nonlaborers (P = 0.036). CONCLUSIONS: Laborers with NTOS are less likely to have a good result from surgical intervention, are unlikely to return to their original occupation, and may require retraining for a non-labor-intensive occupation if they cannot return to their original work.

Effect of renal insufficiency on outcome following infrarenal aortic surgery.

BACKGROUND: This study reviewed the effect of preoperative renal insufficiency on outcome following elective infrarenal aortic surgery. METHODS: The charts of 210 consecutive patients undergoing aortic surgery (occlusive disease, 15%; aneurysmal disease, 78%; or combined disease, 7%) from 1990 to 1995 were categorized into three groups based on preoperative creatinine ([Cr] group 1 Cr < 1.5, n = 171; group 2 Cr 1.5 to 1.7, n = 22; and group 3 Cr > or = 1.8, n = 17) and calculated creatinine clearance ([CrCl] CrCl > 45 mL/min, n = 162 versus CrCl < 45 mL/min, n = 48). Patients with renal artery stenosis or those who required suprarenal cross clamping or emergency procedures were excluded. Differences in postoperative intensive care unit (ICU) stay, ventilator days, dialysis dependence, morbidity, and, mortality were compared. RESULTS: Patients in groups 2 and 3 had an increased incidence of postoperative dialysis dependence (group 2 9%, group 3 8%) when compared with patients in group 1 (group 1: 0%, P < 0.05). Patients in the CrCl > 45 group had a lower mortality rate when compared with patients with a CrCl < 45 (CrCl > 45 0.6% versus CrCl < 45 8%, P <0.05) a lower incidence of dialysis (0% versus 7%, P <0.05), and a lower incidence of postoperative serum creatinine elevation from baseline (CrCl > 45 8% versus CrCl < 45 18%, P <0.05). There was no significant difference in morbidity, ICU stay, or ventilator days between the groups. Upon regression analysis, preoperative CrCl but not Cr was predictive of postoperative mortality (P <0.05). Serum Cr was more predictive than CrCl of impaired renal function postoperatively. CONCLUSIONS: Preoperative CrCl is more accurate than Cr as a predictor of postoperative mortality. Patients with preoperative CrCl < 45 mL/minute who undergo elective aortic surgery have a significant increase in postoperative cardiac-related mortality and dialysis.

Initial experience with venous stents in exertional axillary-subclavian vein thrombosis.

PURPOSE: Exertional thrombosis of the axillary and subclavian veins, also known as Paget-Schrötter syndrome, has been increasingly recognized in recent years as a cause of long-term morbidity. Recent aggressive approaches to treating Paget-Schrötter syndrome have suggested the association of early failure with residual subclavian vein stenosis. As a result, the use of endoluminal stents has been proposed as an aid to venous percutaneous transluminal angioplasty for this disorder. METHODS: This report outlines the therapy of 11 consecutive patients with Paget-Schrötter syndrome who were treated at our institution between October, 1992, and December, 1995. Stents were placed when percutaneous transluminal angioplasty was unsuccessful at achieving an adequate residual lumen. RESULTS: Stents were placed after initial thrombolysis in six patients and in late follow-up in two patients. Of the six patients who had stents placed at initial thrombolysis, first-rib resection was eventually performed in four. In two patients first-rib resection was not performed, and stent fracture occurred in both. Late patency was achieved in the stents of six of the eight patients. CONCLUSIONS: Trials to evaluate stents as an adjunct to conventional therapy seem warranted. The use of stents alone without first-rib resection, however, appears to be associated with stent fracture.

Medical Grand Rounds: refractory hypertension and renal insufficiency in a patient with renal artery stenosis.

Renal artery stenosis has become increasingly common as a cause of refractory hypertension and renal insufficiency. There is a high prevalence of bilateral disease and the lesions tend to progress over time. Newer, less invasive, imaging modalities such as doppler ultrasound, magnetic resonance angiography, and spiral CT scanning are evolving technologies in the diagnosis of renal artery stenosis. Advances in surgical technique, particularly the development of extra-anatomical procedures such as spleno-renal and hepato-renal by pass, have significantly lowered surgical morbidity and mortality and provides revascularization options for patients with complex vascular disease that would previously not have been considered because of their high surgical risk. Improvements in angioplasty technique and the use of stents are broadening the types of lesions that can be successfully approached with these techniques and may be particularly helpful for patients with more severe cardiac or cerebrovascular disease. The benefits of revascularization may be even greater for preservation of renal function than for control of blood pressure in properly selected patients. It is difficult to predict which patients will benefit from surgical revascularization versus medical management of RAS. Knowledge of the progressive nature of RAS, the high prevalence of bilateral disease, and the clinical characteristics that correlate with progression (e.g., decreasing renal size) are helpful in guiding clinical decisions regarding intervention. Additional studies to determine the predictive value of non-invasive tests such as CRS, doppler ultrasound before and after administration of angiotensin converting enzyme inhibitors, and other tests, are needed to assist the clinician in identifying who will benefit most from revascularization both in terms of renal function and blood pressure control.

Non-invasive impedance analysis: a new non-invasive test for graft surveillance.

Detection of failing grafts with early reoperation is clearly associated with better long-term patency than intervention after graft failure. Duplex ultrasonography is more accurate than ankle:brachial index for graft surveillance, but is expensive, time consuming and technically demanding. Non-invasive estimation of graft impedance is now possible. The present study was undertaken to evaluate the utility of non-invasive impedance in detecting the failing vein graft. Sixty-nine grafts in 51 patients were followed over a period of 12 months (April 1992-March 1993). High risk infrainguinal arterial vein bypass patients were entered into a graft surveillance program. Ankle:brachial index, non-invasive impedance and duplex ultrasonography were performed upon discharge, 1 month after surgery and then at 3-monthly intervals. Non-invasive impedance was measured using a mean Doppler flow signal obtained from both upper and lower ends of the graft paired with the mean pulse volume recording obtained from the distal arterial bed. The mean pulse volume recording and flow signals were digitized by discrete Fourier transform and an impedance index generated. An impedance index > or = 0.5 was considered abnormal. Impedance results were compared with ankle:brachial index, duplex ultrasonography and angiography when appropriate, and detected 28 failing and five failed grafts. Non-invasive impedance achieved a sensitivity of 91% and a specificity of 94%. Similarly, duplex ultrasonography was 91% sensitive and 97% specific, while ankle:brachial index was 58% sensitive and 94% specific. Non-invasive impedance is a simple, inexpensive and effective test which detects the failing graft and is an appropriate first-line alternative to duplex ultrasonography for postoperative graft surveillance.

Management of large high-flow arteriovenous malformations of the shoulder and upper extremity with transcatheter embolotherapy.

PURPOSE: To evaluate the efficacy of transcatheter embolization of arteriovenous malformations (AVMs) of the shoulder and upper extremity. PATIENTS AND METHODS: Four men with large AVMs of the shoulder and upper extremity were treated with transcatheter arterial embolization. Symptoms included high cardiac output, pain, paresthesias, and disfigurement. Each patient underwent multiple sessions of embolotherapy. RESULTS: In two patients there was no decrease in cardiac output. In three patients, no permanent decrease in AVM size or resolution of pain was achieved. Two patients experienced postembolization skin necrosis, and one experienced permanent radial neuropathy. CONCLUSIONS: Large, high-flow AVMs in the shoulder and upper extremity may be relatively refractory to intravascular treatment because of the diffuse involvement of the soft tissues by the AVM and the lack of a well-defined nidus. Transcatheter embolotherapy in these lesions should be reserved for patients undergoing resection to help decrease intraoperative bleeding.

Outcomes after major vascular surgery: the patients' perspective.

Surgical outcomes are traditionally defined by rates of morbidity and mortality, as well as the success with which operative objectives are met. Although quality of life after surgery has been sporadically mentioned in the literature since the turn of the century, far greater emphasis has been placed on traditional outcome measures. As the population ages and technological advances permit high-risk interventions in selected elderly patients, the assessment of outcomes with respect to quality of life has become increasingly relevant. To assess quality of life and surgical outcome, 15 patients undergoing simultaneous bilateral renal revascularization at Yale-New Haven Hospital were retrospectively studied. Fifteen charts were reviewed for data on length of hospital stay, number of days in the intensive care unit, operative morbidity, and short- and long-term results. The SF-36, a previously validated health status questionnaire, was used to survey the 11 long-term survivors. Telephone surveys were conducted by a vascular nurse. Of the 11 long-term survivors, nine patients rated their health as good to excellent (eight rated it the same or better than before surgery), eight had no or minimal physical disability, and 10 remained as involved socially as previously. The SF-36 appears to be an effective instrument for assessing postoperative quality of life. It was concluded that this group of patients was satisfied with the outcome of surgery, suggesting that major vascular surgical interventions could be undertaken in selected elderly patients without significant adverse impact on quality of life.

Splenomegaly and variceal bleeding--hemodynamic basis and treatment implications.

Splenectomy and splenic embolization have been advocated as definitive therapy in cirrhotic patients bleeding from varices. While splenomegaly is commonly associated with portal hypertension, no clear hemodynamic link between portal pressure and splenic enlargement has yet been established. In an effort to clarify the hemodynamic significance of splenomegaly in portal hypertensive patients the relationship between spleen size and portal pressure was retrospectively reviewed and the contribution of splenic inflow to portal hypertension prospectively studied. In 50 consecutive cirrhotic variceal bleeders studied angiographically, there was no correlation between spleen size and corrected sinusoidal pressure. Portal pressure was then prospectively measured before and after splenic vein clamping in 12 cirrhotic patients undergoing distal splenorenal shunt. No significant pressure drop occurred following elimination of splenic venous flow. On the basis of these data, there would appear to be no firm hemodynamic basis for splenectomy or splenic embolization alone in the unselective management of cirrhotic patients with variceal bleeding.

Peripheral vascular occlusive disease: accuracy and reliability of time-of-flight MR angiography.

PURPOSE: To determine the accuracy and reliability of magnetic resonance (MR) angiography for identification of stenosis and patent distal vessels in patients with peripheral vascular disease. MATERIALS AND METHODS: Two-dimensional time-of-flight MR angiography and conventional arteriography were performed in 22 patients. Four blinded radiologists independently graded multiple anatomic segments. RESULTS: MR angiography allowed detection of more patent vessel segments than did conventional arteriography. For detection of significant stenosis (> 75%), MR angiography had 43%-67% sensitivity and 74%-89% specificity. Discrepancies in detection of significant stenosis occurred in 39 segments for the most accurate reviewer; 27 of these discrepancies were avoidable. CONCLUSION: For detection of significant stenosis, MR angiography has low to moderate sensitivity and specificity; however, observer variability appears to be a major contributing factor to the discrepancies. Greater reviewer experience or techniques for improving reliability may improve the accuracy of MR angiography in peripheral vascular disease.

Central splanchnic venous thrombosis. Often unsuspected, usually uncomplicated.

Despite the increasingly frequent noninvasive detection of central splanchnic venous thrombosis (CSVT), its pathophysiology and clinical significance remain incompletely understood. We reviewed 50 consecutive cases of partially or totally occlusive thrombosis, primarily of the portal (60%) and splenic (40%) veins. Thirty-eight percent of patients had cancer; 26% had portal hypertension or other conditions associated with splanchnic venous stasis; and in 20%, thrombosis developed postoperatively. Angiography (89%), duplex ultrasonography (46%), CT scan (32%), and MRI (16%) were all useful diagnostic modalities. In 58% of cases, CSVT was clinically unsuspected, and 32% of patients were essentially asymptomatic. Variceal hemorrhage occurred in 30% of cases, and abdominal pain was notable in 26%. Whereas 50% of patients died < or = 6 months of diagnosis, only one of these deaths was directly attributable to CSVT; the remainder were secondary to underlying disease unrelated to the CSVT itself. CSVT, increasingly detected but often unsuspected clinically, is characterized by a self-limited and nonlethal course in the majority of patients. Death from associated disease is, however, common. The treatment and prognosis of CSVT should therefore be dictated by its clinical manifestations and the setting in which it occurs, rather than by the venous thrombosis itself.

Light reflection rheography: a simple noninvasive screening test for deep vein thrombosis.

PURPOSE: The clinical diagnosis of deep vein thrombosis (DVT) is unreliable. Contrast phlebography (CP) continues to be the gold standard, but it is invasive. Although duplex ultrasonography is an accurate, noninvasive alternative, it is expensive, technically demanding, and time-consuming. We postulated that light reflection rheography (LRR), a noninvasive method of assessing the quantity and rate of venous emptying, might be a reliable and inexpensive bedside approach to screening patients with clinically suspected DVT. METHODS: With LRR, infrared light is beamed onto the skin, and the amount of backscattered rays are detected, which indirectly measures the amount of blood present in a volume of the epidermis beneath the LRR probe. Applied to the calf muscle pump, LRR can provide a noninvasive method of assessing blood volume changes in the sample area of skin, in response to venous hemodynamic changes in the lower limb. RESULTS: Sixty-nine limbs in 61 patients undergoing CP for clinically suspected DVT over a period of 12 months also underwent LRR, either just before or within 24 hours of undergoing phlebography. The criteria for diagnosing DVT on CP were presence of filling defect or nonfilling of a venous segment. The result of LRR was considered positive for DVT if the rate of venous emptying was 0.35 or less. With these criteria a sensitivity of 96.4% and specificity of 82.9 were obtained. This resulted in a positive predictive value of 79% and a negative predictive value of 97.1%. CONCLUSIONS: LRR is a simple, inexpensive, and noninvasive bedside test that takes 10 minutes to perform. It is highly sensitive with a high negative predictive value, detecting most cases of DVT, reliably ruling out DVT, and eliminating the need for more time-consuming and costly studies. Therefore it seems to be an appropriate screening test in patients with clinically suspected DVT.

Personality effects on children's speech in everyday life: sociability-mediated exposure and shyness-mediated reactivity to social situations.

Speech and heart rate were continuously monitored during 7 days from morning to evening in 41 Grade 2 children selected for high or low parental judgments of sociability and shyness. Children attended school in the mornings and were free in the afternoons; the child's social situations in the afternoon were reconstructed with the child and a caretaker. During the afternoons sociable children spent more time in conversations than unsociable children, but the groups did not differ in their verbal participation within conversations. Shy children spent as much time in conversations and spoke as much in familiar situations as nonshy children but spoke less in moderately unfamiliar situations. Neither sociability nor shyness had an effect on heart rate reactivity. The results show that sociability affects the exposure, and shyness the reactivity, to situations and that these traits are clearly distinct despite some similarity in lay judgments of personality.