A simplified classification and economical application of anterolateral thigh flap.

BACKGROUND: Anterolateral thigh (ALT) flaps have several anatomical variations and clinical uses. Here, a simplified classification and economical application are introduced. METHODS: A total of 168 ALT flap reconstructions performed between January 2013 and December 2016 were reviewed. Vascular anatomy of the flaps was classified into 5 types: type I (single perforator from the transverse branch), type II (single perforator from the descending branch), type III (multiple perforators from the transverse branch), type IV (multiple perforators from the descending branch), and type V (multiple perforators from both branches). Furthermore, flaps harvested via preservation of the proximal perforator were compared with those that were not. RESULTS: Vascular classification revealed that type IV (50.0%) and type V (32.1%) flaps were the most commonly used. Of these, 50.0% of type IV and 79.6% of type V were harvested as proximal-perforator-preserving distal ALT flaps. The proximal-perforator-preserving group had a smaller flap size (104.4 ± 84.3 cm2 versus 145.9 ± 94.1 cm2, p = 0.003), shorter reconstruction time (266.3 ± 76.1 min versus 302.0 ± 103.0 min, p = 0.013), and fewer donor-site complications (2.4% versus 13.3%, p = 0.009) than the traditional group, whereas the flap success rate was comparable (96.5% versus 96.4%) between them. Five cases received a second ALT flap from the same donor site after 3 failures and 2 metachronous defects. CONCLUSIONS: Multiple perforators in ALT flaps allow the harvesting of 2 ALT flaps from the same donor-site metachronously. Our classification and applications can improve efficiency while reducing donor-site morbidity.

Effects of ischemic preconditioning on economy, VO2 kinetics and cycling performance in endurance athletes.

The aim of this study was to determine the effect of ischemic preconditioning (IPC) on several measures of aerobic function and 4-km cycling time-trial performance. An acute cross-over design was adopted involving eight well-trained cyclists (age 27.0 ± 7.0 years) who completed incremental and square-wave exercise tests for determination of peak O2 uptake (VO2peak), ventilatory threshold (VT) and moderate- and heavy-intensity domain VO2 kinetics, as well as 4-km time trials. All were preceded by IPC, or sham-IPC, involving repeated bouts of thigh blood flow occlusion, interspersed with reperfusion. There was no significant difference between IPC and sham-IPC with respect to VO2peak (4.4 ± 0.6 L min-1 vs 4.4 ± 0.5 L min-1, effect size - 0.01 ± 0.09), VT (3.4 ± 0.6 L min-1 vs 3.5 ± 0.5 L min-1, effect size 0.07 ± 0.28), cycling economy (4.9 ± 4.9%, ES 0.24 ± - 0.24, P > 0.05) or any moderate-domain VO2 kinetic parameter. During heavy-intensity exercise, a reduced end-exercise VO2, slow component amplitude and overall gain was observed following IPC compared to sham-IPC. Though not statistically significant, there was a possibly beneficial effect of IPC on 4-km time-trial mean power output (2.2 ± 2.0%; effect size: 0.18 ± 0.15, P > 0.05). The observed reduction in VO2 slow component and tendency for improved economy and 4-km time-trial performance, albeit small, suggests that acute IPC shows some potential as a performance-enhancing priming strategy for well-trained cyclists prior to high-intensity exercise.

A novel supermicrosurgery training model: the chicken thigh.

BACKGROUND: Supermicrosurgery is an increasingly important technique in reconstructive surgery. It requires a more technically refined skill set compared with standard microsurgery. All currently available biologic training models involve the use of live rats. A nonliving model would be more accessible and cost-effective for practice. We have developed such a model using chicken thighs purchased from a local grocery store. METHODS: The ischiatic neurovascular bundle was identified in 20 chicken thighs and dissected distally to the end of the specimen. The vessel diameters were measured at several points along the artery, vein, and their respective branches. Vessels with diameters in the 0.3-0.8-mm range were then divided and supermicrosurgical anastomoses were attempted. RESULTS: The branching pattern of the ischiatic artery and vein were anatomically consistent with intermediate and terminal secondary and tertiary branches consistently in the range of 0.3-0.8 mm. In all specimens, at least one 0.3-mm vessel could be identified, though additional intramuscular dissection was sometimes required. It was demonstrated that supermicrosurgical anastomoses could be successfully performed using these branches. CONCLUSIONS: This study introduces a novel, convenient, and economical model for supermicrosurgery utilizing easily obtained chicken thighs. The chicken thighs have an anatomically consistent vascular branching pattern, and vessels of appropriate sizes for training can be easily identified and isolated. Surgeons looking to develop or refine supermicrosurgical skills may find this nonliving, biologic model very useful.

Adaptive feedback analysis and control of programmable stimuli for assessment of cerebrovascular function.

The assessment of cerebrovascular regulatory mechanisms often requires flexibly controlled and precisely timed changes in arterial blood pressure (ABP) and/or inspired CO2. In this study, a new system for inducing variations in mean ABP was designed, implemented and tested using programmable sequences and programmable controls to induce pressure changes through bilateral thigh cuffs. The system is also integrated with a computer-controlled switch to select air or a CO2/air mixture to be provided via a face mask. Adaptive feedback control of a pressure generator was required to meet stringent specifications for fast changes, and accuracy in timing and pressure levels applied by the thigh cuffs. The implemented system consists of a PC-based signal analysis/control unit, a pressure control unit and a CO2/air control unit. Initial evaluations were carried out to compare the cuff pressure control performances between adaptive and non-adaptive control configurations. Results show that the adaptive control method can reduce the mean error in sustaining target pressure by 99.57 % and reduce the transient time in pressure increases by 45.21 %. The system has proven a highly effective tool in ongoing research on brain blood flow control.

Validation of a task-specific scoring system for a microvascular surgery simulation model.

OBJECTIVE/HYPOTHESIS: Simulation models can help develop procedural skills outside the clinical setting while also providing a means for evaluation of trainees. Objective Structured Assessment of Technical Skills (OSATS) have been developed for several procedures. The purpose of this study was to demonstrate the construct validity of an OSATS for microvascular anastomosis performed on a simulation model using chicken thigh vessels. STUDY DESIGN: Validation study. METHODS: An expert panel constructed a task-specific checklist for an OSATS for microvascular anastomosis. Twenty surgical staff and trainees performed a microvascular anastomosis of a chicken ischiatic artery. Training level and microsurgical experience were assessed by questionnaire. The performances were recorded and scored by two experts using the task-specific and global scales of the OSATS. RESULTS: Analysis of variance revealed a significant effect of training and microvascular experience for both the task-specific score and global rating scale score (P < .005). Interrater reliability was 0.7. Experience level demonstrated a logarithmic relationship with task time. CONCLUSIONS: The microvascular OSATS applied to the chicken thigh simulator model differentiated between levels of microvascular experience. It demonstrated construct validity and reliability for the assessment of procedural competence using a cost-effective and easily accessible model.

Colour Doppler assessment of the perforators of anterolateral thigh flap and its usefulness in preoperative planning.

UNLABELLED: The role of the anterolateral thigh flap (ALTF) in reconstructive microsurgery grows systematically from mid-eighties of the twenty century until now. Significant anatomic variability of the perforators supplying the ALTF was described in literature. THE AIM OF THE STUDY was ultrasonographic assessment of the ALTF perforators in terms of localization, symmetry, diameter and flow velocity. MATERIAL AND METHODS: The study was performed using ultrasound machine with 12 MHz linear transducer. Both thighs of 30 healthy volunteers (15 men and 15 women) aged from 18 to 60 (mean 37.9) were examined. The line from anterior superior iliac spine (ASIS) to lateral border of the patella was traced, and divided into 10 equal segments. Point where perforator pierces the deep fascia was marked and its diameter was measured and recorded. Maximal flow velocity was measured and recorded. Symmetry of perforator location was confirmed as positive if difference in position of two perforators on both thighs was less than 1.5 cm in diameter. RESULTS: Total number of 119 perforators supplying skin of 60 thighs was found (mean 1.98 perforator per thigh). No perforators were found in 4 thighs (6.6%). Perforators were most abundant in segments from 5 to 7 (74.6%). Perforators with largest diameters and maximal flow velocity reaching 30-47 cm/s were localized in segments 5 and 6. Perforators in segments 4 and 5 were more abundant in men (50.9%) than in women (36.7%). Septal perforators make up to 26.9% of the total. Eighty percent of the septal perforators were localized in segments 5 and 6. Perforator distribution was elicited in the middle of the ASIS--patella line. In the range of ±1.5 cm from the midpoint of the line 33.6% of the perforators were found. CONCLUSIONS: 1. Most of perforators with large diameter and big flow velocity are located in segments 5 and 6. 2. Perforators are more common in men in segments 4 and 5 than in women. 3. No perforators found in 4 thighs suggests that preoperative perforator mapping should become a preoperative routine, which can spare intraoperative dilemmas.

The efficacy of color duplex sonography in preoperative assessment of anterolateral thigh flap.

The anterolateral thigh (ALT) flap has become a workhorse in reconstructive surgery of the head and neck region and the extremities. However, its inconsistent vascular anatomy and frequent intramuscular course of perforators often cause difficulties during the dissection of this versatile flap. Hence, reliable preoperative perforator mapping and identification of vascular anomalies may render the raising of the flap easier and safer. The aim of this study was to evaluate the use of Color Duplex sonography and whether it allows the distinction between septocutaneous and musculocutaneous perforators. For this purpose, the thighs of 13 patients undergoing reconstruction with ALT flaps were examined preoperatively, and results were compared to intraoperative findings. A total of 30 perforators could be detected preoperatively, of which 29 were confirmed during flap dissection. Preoperative Color Duplex sonography correctly predicted the course of all perforators as either running through the vastus lateralis muscle or the intermuscular septum. In our investigations, Color Doppler sonography had a 96.7% positive predictive value and a 96.7% true positive rate in detecting perforators. Color Duplex sonography is a highly reliable tool in the preoperative assessment of ALT flaps. Localization and course of perforators can be determined accurately and vascular anomalies can be identified.

Incremental role of three-dimensional over two-dimensional ultrasound in the assessment of traumatic peripheral arteriovenous fistula.

We present a patient with an accidental self-inflicted stab wound to his right thigh in whom three-dimensional (3D) ultrasound was able to find two communications between the right femoral artery and the femoral vein, in contrast to two-dimensional (2D) peripheral ultrasound which could find only one communication between them, thereby showing an incremental value of 3D over 2D ultrasound.

Preoperative Doppler assessment of perforator anatomy in the anterolateral thigh flap.

Despite its many evident merits as a donor site, the principal disadvantage of the anterolateral thigh flap is the variability in its vascular anatomy. Preoperative assessment by Doppler of the vascular perforators has been advocated as routine. We report the accuracy of this method, and describe the strategy for rescue where adequate perforators are not evident. Eighty-six consecutive patients were marked preoperatively using hand-held Doppler and the pattern was compared with intraoperative findings. Assessment by Doppler predicted a median of 3 (range 0-8) perforator signals, and a median of 2 (range 0-5) was found intraoperatively. This overall trend towards false positives was exaggerated in thin thighs, but in the obese there were more false negative results. In 79% of cases explored medially it would have been possible to raise an apparently viable anteromedial thigh flap. As this can be done without extending the incision, it is the option of choice for rescue, although use of more proximal perforators may often be possible.

In vivo quantification of femoral-popliteal compression during isometric thigh contraction: Assessment using MR angiography.

PURPOSE: To quantify femoral-popliteal vessel deformation during thigh contraction. MATERIALS AND METHODS: Eleven subjects underwent a magnetic resonance (MR) examination of the femoral-popliteal vasculature on a 1.5 T system. A custom 3D balanced steady-state free precession (SSFP) sequence was implemented to image a 15-20-cm segment of the vasculature during relaxation and voluntary isometric thigh contraction. The arterial and venous lumina were outlined using a semiautomated method. For the artery, this outline was fit to an ellipse whose aspect ratio was used to describe arterial deformation, while venous deformation was characterized by its cross-sectional area. RESULTS: Focal compression of the femoral-popliteal artery during contraction was observed 94-143 mm superior to the condyle that corresponds to the distal adductor canal (AC) immediately superior to the adductor hiatus. This was illustrated by a significant reduction (P < or = 0.05) in aspect ratio from 0.88 +/- 0.06 during relaxation to 0.77 +/- 0.09 during contraction. A negligible change in arterial aspect ratio was observed inferior to the AC and in the proximal AC. Similarly, venous area was dramatically reduced in the distal AC region during contraction. CONCLUSION: Rapid 3D SSFP MR angiography of the femoral-popliteal vasculature during thigh contraction demonstrated focal compression of the artery in the distal AC region. This may help explain the high stent failure rate and the high likelihood of atherosclerotic disease in the AC. J. Magn. Reson.

An anatomic assessment on perforators of the lateral circumflex femoral artery for anterolateral thigh flap.

The anterolateral thigh flap was originally described in 1984 as a septocutaneous flap based on the descending branch of the lateral femoral circumflex artery (LCFA). This flap has many advantages for head and neck reconstruction. However, it is not widely used as a result of the broad range of anatomic variation of the cutaneous perforators and because dissection of these perforators is tedious when they are small. The purposes of this study are to classify the vascular anatomy of the LCFA and to assess the suitability of the anterolateral thigh flap for head and neck reconstruction in Koreans. From 38 thigh dissections of Korean cadavers, the LCFA commonly arose from the deep femoral artery and divided into ascending, transverse, and descending branches. In five cases, the LCFA arose directly from the femoral artery. The cutaneous perforators were present in 37 cases except one and the septocutaneous perforators were found in 17 of the 38 cases. Of the 160 perforators, 28 (17.5%) were the septocutaneous perforators and 132 (82.5%) were the musculocutaneous perforators. The average number of cutaneous perforators for the anterolateral thigh flap was 4.2 (range, 0-8), and these perforators were concentrated in the middle third of the anterolateral thigh. The septocutaneous perforators were located more proximally than the musculocutaneous perforators. The average length of the vascular pedicle derived from the descending branch or the transverse branch was 83.3 mm (range, 53.4-124.3 mm). The results of this study suggest that the vascular anatomy of the anterolateral thigh flap was reliable and well suited for head and neck reconstruction in Koreans.

Preoperative color Doppler assessment in planning of anterolateral thigh flaps.

The anterolateral thigh flap has many advantages, but it has not yet achieved widespread use because the perforators exhibit considerable anatomical variation and their locations are difficult to predict preoperatively. The authors performed a prospective study to investigate whether acoustic Doppler flowmetry and color Doppler ultrasonography were helpful for preoperative localization of the perforators in anterolateral thigh flaps. Ten patients scheduled for anterolateral thigh flap surgery were examined preoperatively with both acoustic Doppler flowmetry and color Doppler ultrasonography, and all points where the perforators seemed to penetrate the fascia lata were mapped. The actual perforating points were identified intraoperatively and were compared with the preoperatively mapped points. Fifteen perforators were detected in 10 patients. The concordance rate with acoustic Doppler flowmetry was 40 percent (95 percent confidence interval, 15 to 68 percent; p = 0.05). In contrast, the concordance rate with color Doppler ultrasonography was 100 percent (95 percent confidence interval, 81 to 100 percent; p = 0.05). Color Doppler examination was significantly more accurate than acoustic Doppler examination (determined by the binomial test; p < 0.0014). Three-dimensional anatomical information around the perforators was further useful in elevating flaps. The authors conclude that color Doppler examination can accurately identify the perforators and is useful for planning in anterolateral thigh flap surgery, whereas acoustic Doppler examination is unreliable.

Automated analysis of phase-contrast magnetic resonance images in the assessment of endothelium-dependent flow-mediated dilation.

Measurement of flow-mediated arterial dilation (FMAD) provides information regarding the status of peripheral arterial endothelial function. Although phase-contrast magnetic resonance imaging (PC-MRI) can be used to measure FMAD, the manual analysis of one study (tracing regions of interest and processing data on 100 images) can require six or more hours. To enhance the clinical utility of the PC-MRI assessment of FMAD, we hypothesized that an automated technique (Multi-Stage Intensity Thresholding or MSIT) for determining femoral arterial area and flow before and after cuff inflation over the thigh could be used to evaluate FMAD in a rapid, accurate, and reproducible manner. Compared with manual analysis, automated analysis detected a similar percentage change in peak FMAD between healthy individuals (17.2% vs 16.5%) and patients with congestive heart failure (4.0% vs 5.1%). The correlation between percentage changes in arterial area after cuff release derived manually and automatically was very good (r = 0.93). Analysis time for 100 images averaged 10 minutes with MSIT vs. 6 hours for manual analysis. In conclusion, rapid, accurate assessments of femoral artery FMAD can be obtained using Multi-Stage Intensity Thresholding. This methodology may prove useful for the rapid MRI assessment of peripheral arterial endothelial function in a clinical setting when studying patients with cardiovascular disease.

Preoperative assessment of anterolateral thigh flap cutaneous perforators by colour Doppler flowmetry.

An anterolateral thigh flap is very useful in head and neck reconstruction because of its long and large-caliber vascular pedicle, large skin territory and elevation simultaneous with tumour resection. However, the number and locations of cutaneous perforators vary individually, and thus, it is not widely used because flap elevation is often complicated and time-consuming owing to unexpected anatomical variations. To overcome this disadvantage, we assessed the number and locations of cutaneous perforators preoperatively by colour Doppler flowmetry. These data were compared with the intraoperative anatomical findings and their reliability evaluated. A total of 48 cutaneous perforators were found by preoperative colour Doppler flowmetry scanning of 17 anterolateral thigh flaps. All the perforators except two were found intraoperatively. Doppler scanning failed to detect four perforators. Colour Doppler flowmetry assessment therefore has a 92% true-positive rate and a 95.8% positive predictive value. All the flaps except one included multiple perforators, and sufficient blood circulation was observed in all cases. No flaps were unexpectedly changed to anteromedial thigh flaps or contralateral anterolateral thigh flaps because of inappropriate cutaneous perforators or the absence of perforators. Though this investigation is relatively time-consuming (30-40 min) and requires skill, it is very useful for preoperative flap planning and increases the reliability and safety of elevating an anterolateral thigh flap.

Assessment of tissue blood flow following small artery welding with an intraluminal dissolvable stent.

Using the technique of radioactive 51Cr-labeled biological microspheres, this study evaluated arterial blood flow following small vessel anastomosis by CO2 laser welding and a dissolvable stent in the lumen. A total of 30 Sprague-Dawley rats were divided into two groups. Group A: 11 rats had their femoral arteries ligated on one side. The contralateral side served as a control, with the artery transected and repaired using conventional microsuturing. Group B: 19 rats had their femoral arteries transected and repaired using CO2 laser welding and an intraluminal dissolvable stent technique. The contralateral side was again used as a control using conventional microsuturing. At 1 hr postoperatively, 51Cr-labeled biological microspheres were injected centripetally into the left common carotid artery and the legs and thighs immediately harvested for measurement of radioactivity. All repaired arteries were patent (30/30 in the microsuturing group and 19/19 in the stented welding group), with no detectable stenosis or dilation at the repaired site. Statistical analysis showed that tissue radioactivity (cpm/g) in the ligated group (3,972 +/- 384 in thighs and 3,142 +/- 742 in legs) was significantly lower than in the microsuturing group (7,132 +/- 1,723 in thighs and 6,557 +/- 1,469 in legs) (P < 0.01). In the ligated group, a significant reduction of blood flow was seen in the legs when compared with the thighs (P < 0.05). There was no significant difference in radioactivity when comparing the microsuturing control with the stented welding group, in both thighs (7,064 +/- 2,599 and 7,006 +/- 2,406, respectively; P > 0.05) and legs (6,386 +/- 1,703 and 6,288 +/- 1,757, respectively; P > 0.05). This study provided evidence that the dissolvable stent placed intraluminally does not impair blood circulation and that when coupled with CO2 laser welding offers a high-quality alternative to conventional small vessel anastomosis.

Sonographic assessment of lower limb vein diameters: implications for the diagnosis and characterization of deep venous thrombosis.

OBJECTIVE: The goals of this study were to define the normal range of diameters in the deep veins of the thigh and to compare this range with diameters of veins with acute thrombus and of veins with chronic changes from prior deep venous thrombosis (DVT). SUBJECTS AND METHODS: The anteroposterior diameter of the vein and adjacent artery was measured at five predefined levels in 975 legs of patients referred for sonographic examination for suspected DVT. The mean vein diameter and mean vein-to-artery ratio were calculated for normal veins, vein segments with acute DVT, and vein segments with chronic changes from prior DVT. RESULTS: The diameter of normal deep leg veins was largest at the level of the common femoral vein (mean diameter, 10.5 mm). The diameter progressively decreased until the mid superficial femoral vein and remained relatively constant (mean diameter, 6.4-6.8 mm) more caudally. Similarly, vein-to-artery ratios progressed from a mean ratio of 1.3 in the common femoral vein to 1.2 at other levels. We found no significant differences in vein diameter between the right and the left legs. Vein segments with acute thrombus were larger than corresponding segments of normal veins. However, we found considerable overlap in the ranges of diameter of veins with and without acute DVT. At corresponding levels, veins with chronic DVT tended to be narrower than normal veins; however, the differences were small, and this diameter range also substantially overlaps that of normal veins. CONCLUSION: When grouped, veins with acute DVT were larger than normal veins. Likewise, veins with chronic DVT were smaller than normal veins. Because we found that the ranges of diameters of veins overlapped for different groups of veins, size alone is unlikely to provide compelling evidence for the diagnosis of acute versus chronic DVT, except at extreme diameters. Diameters of veins as revealed by sonography should be interpreted in the context of other sonographic findings.

How accurate are high thigh narrow cuff pressure measurements in the assessment of aorto-iliac obstructive disease?

Thigh cuff pressure measurements are commonly used as a diagnostic method in the assessment of the aorto-iliac (AI) segment of patients with arterial obstructive disease. For a reliable assessment of the AI segment the use of a narrow cuff placed high on the thigh has been advocated. Although this method is commonly used, opinions on its diagnostic value are very divergent. To investigate its diagnostic value the pressure measured with a high thigh narrow cuff was compared with the intra-arterial pressure of the common femoral artery measured at rest and during reactive hyperaemia. Furthermore, the accuracy of these thigh pressures for detecting haemodynamically significant (HDS) AI stenoses was examined. The influence of an occlusion of the superficial femoral artery (SFA) on the pressure measurements was also studied. A correlation coefficient of 0.64 (P less than 0.05) was found between the femoro-brachial index (FBI) at rest and the thigh-brachial index (TBI). Using the TBI as a criterion for detecting a HDS AI stenosis, an accuracy of 73% could be obtained. Furthermore, it appeared that an occluded SFA could influence the pressure measurements dramatically. For clinical practice a TBI less than 0.90, in the presence of a patent SFA, ensures the presence of an HDS AI stenosis. A TBI greater than 1.35 suggests that the AI tract is normal, irrespective of the condition of the SFA. All other values of TBI should be interpreted with caution and only used as a decisive diagnostic method for the assessment of the haemodynamics of the AI segment in combination with other tests.

The assessment of skin blood flow in peripheral vascular disease by laser Doppler velocimetry.

The helium-neon laser Doppler (LD) is designed to measure skin blood flow velocity (SBFV). Flow velocity and pulse wave amplitude are expressed in millivolts (mv) relative to a zero-flow reference. The authors have reviewed their initial experience in ten persons (20 limbs) without peripheral vascular disease (PVD, group I) and nine patients (12 limbs) with severe PVD (group II). The finger, palm, great toe, and forehead had a significantly (P less than 0.05) greater flow velocity than the plantar and dorsal foot, distal and proximal leg, thigh, chest, arm, and forearm. Baseline and hyperemic SBFV, measured at the great toe, were compared in groups I and II. In group I, the baseline SBFV (mv, mean +/- standard error of the mean (SEM] in the great toe was 197 +/- 38 compared with 67 +/- 12 in group-II patients (P less than 0.05). The pulse wave amplitude (mv, mean +/- SEM) was 77 +/- 14 in group I and 5.4 +/- 1.1 in group II (P less than 0.05). The time to maximal hyperemic response (seconds, mean +/- SEM) in group I was 18 +/- 1.5 compared with 150 +/- 14 in group II (P less than 0.05). LD is a sensitive indicator of changes in SBFV, allowing differentiation between normal persons and patients with PVD. The LD tracing in patients with PVD is characterized by a baseline SBFV that is significantly less than normal and also by the attenuation or absence of pulse waves. The diagnostic accuracy is enhanced by the use of reactive hyperemia.

Utility of wide and narrow blood pressure cuffs in the hemodynamic assessment of aortoiliac occlusive disease.

One hundred lower extremities were evaluated by measurement of common femoral intra-arterial pressure and high-thigh Doppler-derived segmental pressures using wide and narrow blood pressure cuffs to assess the accuracy of high-thigh pressures in the evaluation of aortoiliac disease. Sixty-four extremities were also studied by arteriography. The results were analyzed using the common femoral intra-arterial pressure as the standard. The accuracy was poor for both the wide (52%) and narrow (73%) cuff techniques. No significant differences between the two techniques were evident in regard to the incidence of false positive (wide cuff, 75%; narrow cuff, 65%) and false negative (wide cuff, 3%; narrow cuff, 8%) tests. Superficial femoral artery disease was found to be responsible for all false positive tests using the narrow cuff technique (20 of 20) and all but one of the false positive tests using the wide cuff technique (34 of 35). These data indicate that segmental high-thigh pressures are useful primarily as a screening technique (low false negative rate) to exclude hemodynamically significant aortoiliac occlusive disease at rest.

Graduated, static, external compression of the lower limb: a physiological assessment.

A five-chambered pneumatic vinyl sleeve was used to determine the optimum pressure range of graduated, static, external compression of the lower limb, which would be most beneficial in increasing deep venous velocity. The effects of four different ranges of pressure upon deep venous velocity (technetium-99), calf muscle blood flow (xenon-133) and subcutaneous tissue flow (sodium-24) were measured in recumbent patients. The pressure range 18, 14, 8, 10, 8 mmHg produced a significant increase in mean deep venous velocity (P less than 0.02) without any consequent impairment of either calf muscle blood flow or subcutaneous tissue flow. A higher pressure range of 30, 26, 14, 18, 12 mmHg also produced an increase in mean deep venous velocity, but caused a significant impairment of calf subcutaneous tissue flow.