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Biomedical subjects

William C Culp

Publications and source records attributed to William C Culp.

16 recordsLinked to original sources
PubMed2006

Transesophageal echocardiographic evaluation of an intraoperative retrograde acute aortic dissection: case report.

BACKGROUND: We report an intraoperative retrograde dissection of the aorta and its subsequent evaluation by transesophageal echocardiography (TEE). CASE PRESENTATION: A 78 year old woman with an ascending aortic aneurysm without dissection and coronary artery disease was brought to the operating room for aneurysm repair and coronary artery bypass grafting. After initiation of cardiopulmonary bypass through a femoral artery cannula, aortic dissection was noted and subsequently imaged by TEE. CONCLUSION: Retrograde aortic dissection through the femoral artery is life-threatening. Intraoperative TEE can be used to diagnose this uncommon event, and should be considered after initiation of bypass.

Aged↗
PubMed2005

Effectiveness of lipid microbubbles and ultrasound in declotting thrombosis.

The objectives of this study were to determine the effectiveness of lipid-encapsulated microbubbles and ultrasound (US) in recanalizing arteriovenous graft thrombi and the effect that tissue attenuation has on the success rate. A total of 55 thrombotic occlusions were created in four canines. The thrombosed grafts were randomly treated with two different 1-MHz US intensities, low (0.4 to 0.6 W/cm(2)) and high (10 W/cm(2)). Intragraft microbubbles were compared with intragraft saline and with the same dose of microbubbles given IV. IV microbubbles were also given both in the presence and absence of a tissue-mimicking phantom. High-intensity US (10 W/cm(2)) with intragraft microbubbles produced significantly higher patency and flow scores than did US with saline (p < 0.01). US with IV microbubbles had higher success rates in recanalizing thrombosed grafts than did US alone at all intensities. Attenuation reduced the rate at which successful recanalization occurred at both low and high intensities. US and microbubbles are capable of recanalizing acute arteriovenous graft thromboses. Higher intensities may be needed in the presence of tissue attenuation.

Acute Disease↗
PubMed2005

Caval perforation with bronchial communication: a rare complication of long-term venous access.

Superior vena cava (SVC) perforation with bronchial communication is a very rare complication of long-term venous access. A patient recently presented with erosion of a venous port catheter into a bronchus, with infusion of medications into the bronchus and associated SVC syndrome. A high position of the catheter tip against the wall of the SVC and the beveled style of cut on the catheter tip contributed to this complication. A unique combination of percutaneous techniques was helpful in managing this complication, and surgery was avoided.

Aged↗
PubMed2005

Thoracic paravertebral block for percutaneous transhepatic biliary drainage.

Percutaneous transhepatic biliary drainage is a painful procedure most commonly performed after intravenous sedation. Despite systemic opiates and benzodiazepines, most patients experience significant pain during the procedure and in the recovery period. Paravertebral blocks allow the spinal nerve roots and sympathetic chain in the paravertebral space to be anesthetized, and their role in providing analgesia for thoracic and upper abdominal surgical procedures is well-established. Herein a case is described in which thoracic paravertebral blockade dramatically reduced standard intra- and postprocedural analgesic needs and provided superior pain control.

Aged↗
PubMed2004

Intracranial clot lysis with intravenous microbubbles and transcranial ultrasound in swine.

BACKGROUND AND PURPOSE: Destruction of microbubbles by transcutaneous low-frequency ultrasound (LFUS) has been used to lyse adjacent clot and recanalize acutely thrombosed vessels. LFUS with intraarterial microbubbles has been shown to lyse cerebral clot rapidly in pigs without thrombolytic drugs. We hypothesized that intravenous platelet-targeted microbubbles with LFUS may be a rapid noninvasive technique to recanalize thrombosed intracerebral vessels. METHODS: After angiography, 0.5 cc of autogenous thrombus was injected into 1 ascending pharyngeal artery of a pig, occluding it and the rete mirabile. These vessels connect the carotid to the internal carotid and are the main cerebral blood supply. Saline control or intravenous decafluorobutane-sonicated dextrose albumin microbubbles tagged with a subtherapeutic quantity of glycoprotein 2b/3a receptor inhibitor eptifibatide (75 U/kg plus 12 cc of microbubbles administered over 21 minutes), or eptifibatide control, was given with transcutaneous temporal LFUS (1 MHz at 2.0 W/cm2) for 24 minutes. Angiography followed with scoring of declotting and flow. The same protocol was repeated on the contralateral side with the other test fluid so each animal received a saline control and either tagged microbubble or eptifibatide alone. RESULTS: Fifteen pigs completed the protocol with a mean clot age of 4.6 hours. Using tagged microbubbles, 6 of 8 achieved success compared with 0 of 7 receiving eptifibatide alone (P=0.007) and 1 of 15 receiving saline alone (P=0.02). CONCLUSIONS: Intravenous platelet-targeted microbubbles combined with transcranial LFUS can rapidly open acute intracranial thrombotic occlusions. Further development for ischemic stroke therapy is justified.

Animals↗
PubMed2004

Sequential one-lung isolation using a double arndt bronchial blocker technique.

One-lung ventilation and isolation can be performed using a double-lumen endotracheal tube or one of several alternative airway devices. We report a case in which sequential lung isolation was performed by placing two Arndt bronchial blockers through a single-lumen endotracheal tube. Traditional double-lumen tubes can be difficult to place and have potential complications that may be avoided by placing two Arndt blockers.

Bronchi↗
PubMed2003

Carbon dioxide in the aortic arch: coronary effects and implications in a swine study.

PURPOSE: CO2 angiography is considered dangerous in the aortic arch where bubbles may cause critical cerebral and cardiac ischemia. We investigated CO2 distribution, physiologic effects in the heart, methods of detection and treatments. METHODS: Eight pigs had CO2 and iodinated contrast arch angiograms in supine and both lateral decubitus positions. An electrocardiogram, physiologic data and cardiac ultrasound were obtained. Therapies included precordial thumps and rolls to lateral decubitus positions. RESULTS: Supine high descending aorta CO2 injections floated retrograde up the arch during diastole and preferentially filled the right coronary artery (RCA): mean score 3.5 (of 4), innominate artery 2.4, left coronary artery 1.2; n = 17; p = 0.0001. Aortic root injections preferentially filled the RCA when the animal was supine, left coronary in the right decubitus position, and showed a diffuse pattern in the left decubitus position. Right decubitus rolls filled both coronaries causing several lethal arrhythmias. Precordial thumps successfully cleared CO2. Ultrasound is a sensitive detector of myocardial CO2. CONCLUSION: Arch distribution of CO2 primarily involves the RCA. Diagnostic ultrasound detects cardiac CO2 well. Precordial thumps are an effective treatment.

Angiography, Digital Subtraction↗
PubMed2003

Microbubble-augmented ultrasound declotting of thrombosed arteriovenous dialysis grafts in dogs.

PURPOSE: Transcutaneous low-frequency ultrasound (LFUS) can effectively lyse clots in the presence of microbubbles. This study was designed to test the commercially available human albumin microspheres injectable suspension octafluoropropane formulation, Optison, to establish efficacy and assess US parameters of intensity and wave modes in a canine model of a thrombosed arteriovenous (dialysis) graft. MATERIALS AND METHODS: Arteriovenous grafts in five dogs were cannulated, temporarily ligated, and thrombosed. Different declotting techniques were randomized to treat nine groups. Control groups involved direct saline (4.5 mL) clot injection in 0.5-1.0-mL increments. One group underwent peripheral intravenous microbubble injection (13.5 mL). Six groups underwent direct incremental clot injection of 4.5 mL of microspheres with LFUS for 30 minutes in 3-5-minute increments with use of various intensity settings in continuous-wave and pulsed-wave (PW) modes. At each increment, angiography was used to grade flow, declotting, and overall success. RESULTS: One hundred four procedures showed success in all 24 high-intensity PW modes (1.2-2.0 W/cm(2)); only one of 20 control experiments was successful (P <.0001). Medium-intensity modes yielded intermediate success rates. Lowest-intensity direct-injection groups and intravenous and control groups ranked lower. Results at 30 minutes were better than at 15 minutes (P <.0001). CONCLUSIONS: LFUS with direct injection of microbubbles is effective in lysing moderate-sized clots and recanalizing thrombosed arteriovenous grafts. It best succeeds at the higher range of intensity settings tested in PW mode. Further development is justified.

Albumins↗
PubMed2003

Microbubble potentiated ultrasound as a method of stroke therapy in a pig model: preliminary findings.

PURPOSE: Low-frequency ultrasound (LFUS) with intraarterial or intravenous microbubbles can recanalize thrombosed dialysis grafts and arteries. A similar method for declotting intracranial arteries in an animal model has been developed. MATERIALS AND METHODS: Swine underwent selective cerebral angiography, and 1 mL of 2-6 hour old clot was placed in one ascending pharyngeal artery and rete mirabile. This occluded the primary brain blood supply from the rete mirabile in the base of the skull. Human albumin octafluoropropane microbubbles were injected through the same catheter in 0.5-1.0-mL doses for a total of 4.5 mL in 21 minutes. Transcutaneous pulsed-wave 1-MHz ultrasound was administered through a temporal approach using 2.2 W/cm(2). Repeated angiography was performed through 24 minutes. Saline controls underwent an identical process on the opposite side. Declotting was graded on a scale of 0-4, and flow used the 0-3 thrombolysis in myocardial infarction (TIMI) scale. Success was defined as declotting of grade >/= 3 (>70% clearing) with flow of >/= 2. RESULTS: Seven pigs received 14 declotting sequences. Average clot age was 217 minutes. Average declotting score was 3.1, and flow was 2.1 for microbubbles and 1.4 and 0.1 for saline controls, P =.016 in each. Success occurred with microbubbles in six of seven attempts and in controls in zero of seven attempts, P =.031. CONCLUSIONS: LFUS with microbubble augmentation rapidly lyses intracranial clot and restores flow at ultrasound ranges similar to those required in humans. Further development of this possible acute stroke therapy is justified.

Animals↗
PubMed2003

Changes in ultrasonographic echogenicity and visibility of needles with changes in angles of insonation.

PURPOSE: To objectively compare the echogenicity of several types of needles at clinically important angles of insonation. MATERIALS AND METHODS: Four commercial needles (Echotip, Mini-Stick, Echo-Coat, Surflo) and a prototype dimpled needle were tested in a liver phantom at angles of insonation ranging from 90 degrees to 15 degrees. Photodensity measurement determined echogenicity levels in arbitrary echogenicity units (EU). RESULTS: At 90 degrees angles of insonation all needles were easily seen (60-76 EU) and echogenic levels were similar (P =.264). All values decreased with angulation. From the 35 degrees to 15 degrees angles, the prototype and Echotip needles were superior (P <.05). At 15 degrees the values were 43 EU for the prototype needle, 40 EU for the Echotip needle, 9.0 EU for the Echo-Coat needle, and 5.0 EU for the Surflo needle. CONCLUSION: With angulation, all needles drop in echogenicity, with prototype dimpled and Echotip best maintaining visibility at clinically important angles.

Liver↗
PubMed2002

Detection of room air contamination of angiographic CO2 with use of a gas analyzer.

The purpose of this study was to describe a practical method to detect room air contamination in CO2 used for angiography. Samples of CO2 with known room air contamination levels were used in a "bag system" of CO2 delivery and sampled by a gas analyzer commonly used in anesthesia. Nitrogen levels were reliably detected indicating contamination with as little as 2% air. Oxygen levels were reliably detected, indicating contamination with as little as 5% air. Measured CO2 values were unreliable with higher-than-true values at all levels except 100%. All clinically important amounts of N2 and O2 contamination were readily detected by this practical method.

Air↗
PubMedDate not supplied

Paravertebral block: an improved method of pain control in percutaneous transhepatic biliary drainage.

BACKGROUND AND PURPOSE: Percutaneous transhepatic biliary drainage remains a painful procedure in many cases despite the routine use of large amounts of intravenous sedation. We present a feasibility study of thoracic paravertebral blocks in an effort to reduce pain during and following the procedure and reduce requirements for intravenous sedation. METHODS: Ten consecutive patients undergoing biliary drainage procedures received fluoroscopically guided paravertebral blocks and then had supplemental intravenous sedation as required to maintain patient comfort. Levels T8-T9 and T9-T10 on the right were targeted with 10-20 ml of 0.5% bupivacaine. Sedation requirements and pain levels were recorded. RESULTS: Ten biliary drainage procedures in 8 patients were performed for malignancy in 8 cases and for stones in 2. The mean midazolam use was 1.13 mg i.v., and the mean fentanyl requirement was 60.0 microg i.v. in the block patients. Two episodes of hypotension, which responded promptly to volume replacement, may have been related to the block. No serious complications were encountered. The mean pain score when traversing the chest wall, liver capsule, and upon entering the bile ducts was 0.1 on a scale of 0 to 10, with 1 patient reporting a pain level of 1 and 9 reporting 0. The mean peak pain score, encountered when manipulating at the common bile duct level or when addressing stones there, was 5.4 and ranged from 0 to 10. CONCLUSIONS: Thoracic paravertebral block with intravenous sedation supplementation appears to be a feasible method of pain control during biliary interventions.

Adult↗
PubMedDate not supplied

Popliteal artery disease: diagnosis and treatment.

The popliteal artery is a relatively short vascular segment but is affected by a unique set of pathologic conditions. These conditions, which may be common throughout the arterial system or exclusive to the popliteal artery, include atherosclerosis, popliteal artery aneurysm, arterial embolus, trauma, popliteal artery entrapment syndrome, and cystic adventitial disease. The clinical manifestations, imaging appearances, and treatment options associated with these pathologic conditions differ significantly. Consequently, the radiologist should be familiar with these conditions to direct imaging for accurate diagnosis and treatment and to prevent loss of limb.

Adolescent↗