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Biomedical subjects

R Neville

Publications and source records attributed to R Neville.

At least 19 recordsLinked to original sources
PubMed2001

Common femoral artery ligation and local debridement: a safe treatment for infected femoral artery pseudoaneurysms.

PURPOSE: The management of infected femoral artery pseudoaneurysms (IFAPs) is difficult and controversial. Use of synthetic or autologous conduit during arterial revascularization in these cases is complicated by the presence of sepsis and unavailability of autologous venous conduit. We present the results of common femoral artery (CFA) ligation and local drainage with debridement for the treatment of IFAP. METHODS: A retrospective chart review of six consecutive patients from 1995 to 1999 who presented with IFAP from intravenous drug abuse was performed. Inpatient records, anesthesia records, and outpatient clinic charts were reviewed. All patients were men with right-sided lesions. All six patients abused heroin, and five (83%) abused heroin and cocaine. All six patients had a duplex ultrasound scan, and five (83%) patients had a digital subtraction angiogram to confirm the clinical diagnosis. Proximal vascular control was achieved retroperitoneally through an oblique suprainguinal incision. After vascular isolation and test clamping of the distal external iliac artery (EIA), the pedal pulses were examined with continuous wave Doppler scan. If a Doppler signal was present, this was followed with CFA ligation and local drainage and debridement of the IFAP. RESULTS: Pain at injection site and fever with chills were present in five (83%) and three (50%) patients, respectively. A pulsatile groin mass and thigh or leg edema were present in five (83%) patients. Three patients (50%) had a palpable pedal pulse, and all six had a Doppler signal over a pedal artery at presentation. The mean white cell count was 15.6 thousand per cubic millimeter (range, 9.2-19.3). All patients had a Doppler signal over a pedal artery after distal EIA/CFA test occlusion and ligation. None of the patients required an amputation, and all six patients regained their preoperative ambulatory status. The mean follow-up period was 25 months. Two patients had mild claudication (5-6 blocks) at 18 months and 2 years after surgery. All six patients received drug rehabilitation, but they admitted to drug abuse after surgery and rehabilitation. CONCLUSION: CFA ligation and local debridement are safe treatment modalities for IFAP, if there is an intraoperative Doppler signal over a pedal artery during test occlusion of the distal EIA/CFA. CFA ligation avoids the use and therefore the risk of synthetic conduit infection, because there is a high incidence of postoperative drug injection despite aggressive drug rehabilitation.

Adult↗
PubMed2001

Asthma care by nurse practitioners in the United States.

PURPOSE: To survey nurse practitioners (NPs) in the United States on their level of input to asthma care prior to enrolling in The National Asthma and Respiratory Training Centre (NARTC) specialist asthma education program in the UK. DATA SOURCES: Responses of 134 (66%) of the 202 NPs who self-selected for enrollment in the NARTC program on a preliminary questionnaire. CONCLUSIONS: Nearly all (133 or 99%) currently work with asthmatics and 122 (91%) prescribe asthma drugs. Only 92 (69%) measure peak flow(PF), 84 (63%) check inhaler technique, 76 (57%) teach use of a home PF meter and diary, and 63 (47%) provide written self-management plans on any regular basis. Many have not established follow-up procedures (56 or 42%), or evaluated their asthma management practices (55 or 41%). IMPLICATIONS FOR PRACTICE: Successful asthma management requires correct medication, systematic follow-up, patient education, and self-management. Specialist asthma training should encourage practitioners to combine effective drug usage with a long-term preventative approach.

Asthma↗
PubMed2000

Homocysteine accelerates endothelial cell senescence.

In this study we demonstrate that exposure of cultured endothelial cells to homocysteine significantly accelerates the rate of endothelial senescence. Examination of telomere length demonstrates that homocysteine increases the amount of telomere length lost per population doubling. The effects of homocysteine on both senescence and telomere length are inhibited by treatment with the peroxide scavenger catalase. Chronic exposure of endothelial cells to homocysteine also increases the expression of two surface molecules linked to vascular disease, intracellular adhesion molecule-1 (ICAM-1) and plasminogen activator inhibitor-1 (PAI-1). Interestingly, the level of expression of both ICAM-1 and PAI-1 correlates with the degree of endothelial senescence. Taken together, these results suggest that homocysteine accelerates the rate of cellular senescence through a redox-dependent pathway. In addition, it suggests that chronic oxidative stress in the vessel wall may hasten the rate of senescence and that the senescent endothelial cell may in turn be pro-atherogenic.

Arteriosclerosis↗
PubMed1995

Angioscopic evaluation of an endoluminal aortic graft: the first clinical experience.

PURPOSE: Balloon aortoscopy has been described for viewing aortic endoluminal anatomy and guiding aortic stent placement in animals. We report the first clinical use of this technique to visually inspect the proximal portion of a 1-year-old endovascular aortic graft, its proximal fixation stent, and its relationship to the renal arteries. METHODS: The aortoscope is a modified fiber-optic endoscope that is fitted over the lens with a transparent, saline-filled balloon for blood displacement. Its performance was evaluated in a 62-year-old woman who had a Parodi-type Dacron/modified Palmaz stent endoluminal graft implanted to exclude an infrarenal aortic aneurysm in 1994. One year later, during an angioplasty procedure for symptomatic left subclavian and left common iliac artery stenoses, the 1-year-old endoluminal graft was inspected with the balloon-tipped angioscopic assembly. RESULTS: Introduced via the left brachial artery, the aortoscope provided a panoramic view of the endoluminal surface through the solution-filled balloon. The endoluminal aortic graft was clearly identified, as were both renal artery orifices proximal to the graft. The surface of the proximal stent was smooth and without exposed metal. No complications occurred with the angioscopy technique. CONCLUSIONS: Aortic angioscopy can be used to evaluate endoluminal aortic grafts and endoluminal anatomy. It provides clear, magnified views that may be useful for guiding precise placement and assessing the function and healing of endoluminal devices in the aorta.

Angioscopy↗
PubMed1993

Arterial intimal flaps: a comparison of primary repair, aspirin, and endovascular excision in an experimental model.

The optimal management for traumatic arterial intimal injuries is unresolved. Three therapeutic options were compared in an experimental model employing a standard intimal flap created in 51 canine superficial femoral arteries. Group 1 (14 arteries) underwent resection with end-to-end repair. Group 2 (19 arteries) received acetylsalicylic acid (ASA) and observation only. Group 3 (21 arteries) underwent endovascular excision of the flap with angioscopic guidance. Control intimal flaps (18 arteries) were created and observed without further intervention. Patency in group 1 (primary repair) and group 2 (ASA) was 100%; the patency in both was significantly (p < 0.05) greater than in the controls, which was 67%. Patency in group 3 (endovascular excision) was 79%. Residual luminal defects were observed in only 8% of the arteries repaired primarily, but in 76% of the aspirin-treated arteries. Residual luminal defects following endovascular excision were present in 53% of the arteries remaining patent. Although resection and primary repair (group 1) provided better results than observation alone (control), addition of ASA (group 2) also sustained patency. However, a high incidence of residual intimal defects occurred, the natural history of which is unknown. While endovascular excision (group 3) may become a feasible alternative, current technology provided inferior patency with frequent residual intimal defects. These results suggest that observation alone supplemented with antiplatelet medication (ASA) may be adequate treatment, but longer follow-up is necessary for confirmation.

Angioscopy↗
PubMed1992

Dose-dependent smooth muscle cell proliferation induced by thermal injury with pulsed infrared lasers.

BACKGROUND: Recently, laser-heated and radio frequency-heated balloon angioplasty techniques have been proposed as a means to treat or minimize dissection and elastic recoil but have been associated with a high rate of clinical restenosis. Similarly, pulsed laser angioplasty techniques proposed to minimize thermal injury while ablating obstructing atheroma have failed to reduce clinical restenosis. Because "hot balloon" and pulsed laser angioplasty create both mechanical and thermal injury, it has been difficult to discern the cause of the smooth muscle cell (SMC) proliferation resulting in restenosis and whether such magnitude of proliferation is predictable and dose related. This study was undertaken to explore these issues. METHODS AND RESULTS: Localized thermal lesions accompanying efficient ablation were created with a pulsed Tm:YAG laser in nine rabbit aortas, which consistently led to a focal proliferation of SMC that filled the ablated region by 4 weeks. Transcutaneous Ho:YAG pulsed laser irradiation at multiple independent sites of 24 central rabbit ear arteries without ablation led to brief approximately 30 degrees C thermal transients and thermal damage to the artery wall resulting in significant neointimal proliferation by 3 weeks and a mean cross-sectional narrowing of 59 +/- 17% at a dose of 390 mJ/mm2. Acute and chronic responses to varying total energy deposition were studied by histology after the rabbits were killed at 2 hours to 4 weeks. Arterial segments midway between laser injuries were unaffected and served as internal controls. Neointimal proliferation at 3 weeks after laser injury exhibited a clear dose dependence. Mean cross-sectional narrowing increased from 34 +/- 10% to 85 +/- 15% as laser fluence increased from 240 mJ/cm2 to 640 mJ/cm2 (r = 0.84). Similarly, cross-sectional narrowing caused by SMC neointimal proliferation increased from 20 +/- 10% to 77 +/- 17% for a fixed surface irradiation as the depth of the most superficial arterial media decreased from 600 microns to 330 microns (r = 0.94). CONCLUSIONS: Thermal injury to the arterial wall is a potent stimulus for SMC proliferation and may necessitate reduction in laser or thermal energy used for angioplasty. Moreover, a dose-response relation exists between the degree of thermal injury and SMC proliferative response. Hence, this technique could be used as a practical model of restenosis suitable for screening therapies for inhibition of SMC proliferation.

Animals↗
PubMed1991

Vascular responsiveness in obstructed gut.

Multiorgan system failure due to hypotension and sepsis is an important cause of death in patients with bowel obstruction. We have investigated the pathophysiology of this entity in an animal model. After 5 days of bowel obstruction, blood flow in the superior mesenteric artery was measured with and without Pitressin and norepinephrine given in separate experiments. In controls, Pitressin in moderate dosages caused a substantial fall in gut blood flow, which was not seen in obstructed animals (blood flow reduction 52 percent vs. 11 percent in sham and obstructed animals respectively, P less than 0.01). Similarly, norepinephrine infusion had less of an effect on gut blood flow in obstructed animals (blood flow reduction 79 percent vs. 58 percent sham vs. obstructed animals (P less than 0.05). Thus, both agents had dose-related effects on gut blood flow, which was maintained at a higher level throughout the drug infusion periods in the bowel of obstructed animals, demonstrating that splanchnic flow is less responsive to vasoactive drug infusion under these experimental conditions. Because splanchnic vasoconstriction is an important feature of normal hemodynamic homeostasis, we suggest that these results may help explain some aspects of the pathophysiology of multiorgan failure caused or worsened by systemic hypotension seen in bowel obstruction.

Animals↗
PubMed1987

Local tumor recurrence after curative resection for rectal cancer. A ten-hospital review.

Local tumor recurrence rates after curative rectal cancer surgery with the end-to-end anastomosis stapler (EEA) are reportedly high. Therefore, a retrospective review in ten Yale-affiliated hospitals was undertaken to establish the outcome of surgical resection for rectal cancer in this patient population. Of those 373 patients who had had curative resections, 192 (52 percent) were abdominoperineal resections (APR); 105 patients (28 percent) had restorative resections with sutured anastomoses, and the EEA stapler was used in 76 patients (20 percent). There was an equal distribution of tumors in the various Dukes' stages in all three procedures. Local tumor recurrence was: APR 19 percent, SUT 17 percent, and EEA 24 percent, but local tumor recurrence was more frequent after EEA than APR for tumors 7 to 10 cm from the anal verge (32 vs. 13 percent, respectively, P less than 0.05), and the time to recurrence was least in EEA patients. It is concluded that local tumor recurrence is higher than expected for all three procedures and that the EEA stapler was associated with a greater risk of local tumor recurrence. These findings are attributed to surgeon-related technical operative factors rather than to the nature of the tumors themselves.

Adult↗
PubMed1987

Somatostatin and analogs lack splanchnic vasoconstrictive effects in anesthetized pigs.

Due to an apparently selective vasoconstrictive effect on the splanchnic circulation, somatostatin (SRIF) has been advocated for the treatment of variceal hemorrhage. The present study was designed to compare and contrast the systemic and splanchnic hemodynamic effects of SRIF and two of its long-acting analogs (SMS 201,995 and L 363,568) with those of Pitressin. Anesthetized pigs were subjected to laparotomy for placement of an electromagnetic flowmeter on the main trunk of the superior mesenteric artery (SMA). Systemic hemodynamic parameters of arterial blood pressure and cardiac output were monitored with thermodilution catheters. Portal venous blood was collected for measurement of plasma levels of SMS 201,995 and L 363,568 and for determination of gastrin levels during infusion of the latter analog. Experimental drugs were administered via an aortic cannula in a range (5-10 mg/kg bolus and 5-10 mg/kg/min continuous infusion) of dosages. At the higher dosages, SRIF, SMS 201,995, and L 363,568 decreased SMA blood flow (mean% +/- SD) 5.6 +/- 2.2, 1.6 +/- 4.4, and 8.0 +/- 3.8 after 10 min. None of the values achieved significance when compared to variation in baseline determinations. Pitressin (0.25 units, intravenously) produced a consistent and highly significant (P less than 0.001) reduction-in SMA flow after 5 min. Pharmacologic levels of SMS 201,995 and L 363,568 were reliably achieved in portal blood and the latter produced significant reduction (P less than 0.05) in portal venous levels of gastrin. SRIF and its long-acting analogs produced no significant splanchnic nor systemic hemodynamic effects in this model.

Anesthesia↗