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Biomedical subjects

B Sigel

Publications and source records attributed to B Sigel.

At least 55 records · Page 3Linked to original sources
PubMed1989

Overview of benefits of operative ultrasonography during a ten year period.

From 1979 to 1988, we have performed operative ultrasonography in 2,299 operations in various surgical fields. By analyzing the results of operative ultrasonography, we defined and summarized its benefits into four categories: acquisition of new information not otherwise available; complement to or replacement for operative radiography; guidance of surgical manipulation; and confirmation of completion of operation. Based on one or more of these benefits occurring, operative ultrasonography was judged to be useful in 2,103 of 2,299 operations (91.5%). The overall impact of operative ultrasonography has been to reduce surgical tissue dissection, reduce operating time, decrease the need for operative radiography, and enable surgeons to devise new surgical procedures. Because of its benefits, the wider use of operative ultrasonography is encouraged.

Humans↗
PubMed1989

Operative ultrasonography for lung cancer surgery.

During 60 operations for lung cancer, high-resolution (7.5 MHz) operative ultrasonography was performed to evaluate direct cardiovascular invasion of tumor (24 operations), lymph node metastasis (30 operations), liver metastasis (13 operations). Immediately after thoracotomy or sternotomy but before tissue dissection, operative scanning enabled delineation and evaluation of the evaluation of the vessels and heart (atrium) behind or within the tumor and detection of regional lymph nodes. The accuracy of operative ultrasound in diagnosing the presence or the extent of cardiovascular invasion was 91.7% (22 of 24 operations), which was significantly (p less than 0.02) higher than preoperative studies (62.5%), including computed tomography and angiography. Of the 24 surgical procedures, 23 were consistent with operations proposed on the basis of operative ultrasound findings, whereas only 16 were consistent with preoperatively proposed (p less than 0.01). Operative ultrasound provided the capability of depicting lymph nodes as small as 3 mm. More lymph nodes (8.0 +/- 1.84 nodes per cancer) were detected with operative ultrasound than with computed tomography (4.8 +/- 1.56 nodes) (p less than 0.001); however, the sensitivity and specificity of operative ultrasound in determining lymph node metastasis were 82.4% and 67.3%, respectively. No liver metastasis was identified. The information provided by operative ultrasound regarding cardiovascular invasion and lymph node and liver metastasis was considered helpful in selecting the type of surgical procedure an in avoiding unnecessary tissue dissection.

Adult↗
PubMed1987

The significance for morbidity and mortality of Doppler-absent pedal pulses.

The 1-month prognosis of 91 limbs with a pulseless foot in 49 patients was determined and related to elements of the physical examination, including Doppler ultrasonography. The risk factors that could predict loss of limb and death in this group of patients were determined. Gangrene and atrophy coupled with absent ultrasound signals predicted a 75% risk of loss of limb; this occurred despite attempted surgical intervention. Absence of Doppler signals in both ankle arteries was the strongest risk factor for predicting death. This is probably because ultrasound signals are absent only when arterial disease is far advanced. We conclude that Doppler ultrasound examination of the pulseless foot yields useful prognostic information relative to the fate of the limb and the patient who possesses such a limb.

Amputation, Surgical↗
PubMed1987

Protamine-induced platelet aggregation and clotting investigated by ultrasound.

Using high-resolution real-time ultrasound to monitor platelet aggregation and plasma clotting, the effect of protamine on platelets was evaluated in a dynamic system of plasma in vitro. Protamine induced platelet aggregation preceding plasma clotting at both low (1.6 s-1) and moderate (22.6 s-1) shear rates. The onset of aggregation and clotting was accelerated at the higher shear rate. Low-shear clots were heterogeneous on ultrasonic imaging, whereas moderate-shear clots were more densely homogeneous. Protamine-induced platelet aggregation was reversed by additional heparin. Pretreatment of plasma with prostacyclin prevented protamine-induced aggregation, but clot formation occurred. However, such clots were less echogenic. EGTA and hirudin inhibited both aggregation and clotting. Our ultrasonic aggregometry showed that platelet aggregation was induced by protamine before clots formed, and that not only shear rate but platelet activation might affect the rate and composition of plasma clots.

Adult↗
PubMed1986

Detection of unrecognized liver metastases from colorectal cancers by routine use of operative ultrasonography.

The importance of diagnosis and detection of liver metastases cannot be overemphasized for the treatment and prognosis of colorectal cancers. As a new diagnostic technique, operative ultrasonography has been performed during 33 operations for colorectal cancers including three operations for metachronous liver metastases. Of these, in five patients (15.2 percent) ultrasonography using 5- or 7.5-MHz instruments identified metastatic tumors that had not been diagnosed during preoperative imaging studies or at exploration. Most of these tumors were approximately 1 cm in size and nonpalpable. Cases of these five patients are presented in this report. High-resolution operative ultrasonography is considered to be a valuable method for detection of unrecognized metastatic tumors and for precise localization and spatial assessment of these hepatic lesions. Because it is safe, simple, and highly sensitive, the routine use of operative ultrasound is encouraged during surgery upon colorectal cancers for systematic screening of metastatic liver tumors.

Adult↗
PubMed1986

Deterioration of venous function in normal lower extremities during daily activity.

The change in venous function during the course of the day was studied noninvasively in 50 normal lower extremities of 25 physically active normal subjects. Venous refilling time, measured by photoplethysmography, was significantly shorter (p less than 0.0001), and venous capacitance, measured by impedance plethysmography, was significantly reduced (p less than 0.04) after 5 hours or more of daily activities performed in the upright position. Abnormally short venous refilling time (less than 18 seconds) developed in 21% of the extremities, which had a normal venous refilling time earlier in the same day. Lower extremity symptoms of ache, pain, or swelling were reported more frequently in extremities that developed an abnormal venous refilling time. There was a trend toward a greater change in venous refilling time during the day in symptomatic lower extremities than in asymptomatic limbs (p = 0.07).

Adult↗
PubMed1986

Normal stomach wall and gastric cancer: evaluation with high-resolution operative US.

Operative ultrasound examinations were performed using a 7.5-MHz transducer during nine operations for advanced gastric cancers and during six for early cancers. Normal stomach wall showed five layers that corresponded to histologic structures. Fourteen of 15 tumors, including nonpalpable early cancers, were localized with ultrasonography. In addition, both depth of penetration and lateral wall extension of the gastric cancers were precisely determined with this technique. Our preliminary results indicate that high-resolution operative ultrasonography may become a diagnostic aid during gastric cancer operations.

Humans↗
PubMed1986

Sonographic evaluation of platelet aggregate retention in a vortex within a simulated venous sinus.

To examine the possible role of venous-valve pockets in enhancing platelet aggregate retention and deposition, in vitro experiments using real-time ultrasonography were performed in a venous-sinus flow model under controlled flow conditions. In each of 10 experiments, adenosine diphosphate (ADP)-induced platelet aggregates in plasma were circulated in both test and control models at upstream shear rates from 60 to 0 sec-1. High-resolution, real-time, B-mode ultrasonography was used to detect and measure the platelet aggregates. Vortex flow was observed in all poststenotic segments, particularly in the sinuses. With reduced shear rates, platelet aggregates increased in size within the vortices and subsequently deposited in the dependent poststenotic tube surface, especially in the sinuses. In conclusion, this study using real-time ultrasonography indicates that the presence of a venous sinus greatly accentuates vortex formation, which, in turn, augments the retention and deposition of platelet aggregates. This relation may provide an explanation for mechanisms that would cause thrombosis to originate in venous-valve pockets.

Adult↗
PubMed1985

The effect of extreme acid and alkali changes upon the echogenicity of blood.

The degree of red cell aggregation is dependent upon multiple conditions. The purpose of these experiments was to ultrasonically determine the threshold and reversibility of human red cell aggregation to extreme pH changes at varying shear rates. Real-time B- and A-mode ultrasonography were used to measure echogenicity. Measurements were recorded at original, acidic, and alkaline pH and following return of both acidic and alkaline pH to neutral pH levels. The results showed that 1) neutral red cell suspensions did not become echogenic at any shear rate; 2) acidification produced a shear-related, partly reversible echogenicity; and 3) alkalinization caused a less intense but more shear-resistant and less reversible echogenicity. Alkalinization produced a microscopically discernible greater persistence of intense red cell aggregation. Cell membrane protein loss was detected by electrophoresis.

Adult↗
PubMed1985

Localization of an occult insulinoma by intraoperative ultrasonography.

Intraoperative ultrasonography has not been used previously to locate an insulinoma that was not surgically palpable or that could not be seen by selective arteriography. In this report we described a patient with an insulinoma localized to the pancreatic head identified by transhepatic portal venous sampling but not by selective arteriography or palpation. At operation intraoperative ultrasonography demonstrated an 8 mm tumor in the pancreatic head and guided the successful enucleation.

Adenoma, Islet Cell↗
PubMed1985

Operative ultrasonography in the biliary tract during pregnancy.

Operative roentgenographic cholangiography entails problems during pregnancy because of the hazard of radiation to the fetus and mother. In 450 biliary tract operations in which real-time B-mode operative ultrasonography was performed, five were for diseases of the biliary tract during pregnancy. Operative ultrasound correctly revealed non-palpable stones in the gallbladder in one patient and in the common bile duct in three patients. Furthermore, operative ultrasound provided anatomic information, such as dilation or stenosis of the common bile duct. Of seven possible occasions in which roentgenography would customarily be expected to be performed, operative cholangiography was used only once. Thus, ultrasound significantly reduced the number of operative roentgenographic studies. Operative ultrasonography was not associated with any complications and significant time delays. It is concluded that operative ultrasonography can replace operative roentgenographic cholangiography as a screening procedure for gallbladder and common duct calculi at biliary tract operations during pregnancy.

Adult↗