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Biomedical subjects

G G Nicholas

Publications and source records attributed to G G Nicholas.

At least 19 recordsLinked to original sources
PubMed2000

Carotid endarterectomy outcomes research: reduced resource utilization using a clinical protocol.

BACKGROUND AND PURPOSE: The purpose of this study was to examine the necessity of intensive care unit (ICU) utilization following carotid endarterectomy (CEA) and to identify patients who can be managed postoperatively on a vascular unit using a clinical protocol. METHODS: Medical records of 50 patients admitted to the ICU following elective CEA were reviewed retrospectively for patient characteristics, morbidity, mortality, length of stay (LOS), and ICU intervention. Prospectively, the next 200 patients were routed to either a vascular unit or ICU, based on a clinical protocol. Endpoints were mortality, stroke, myocardial infarction, total hospital LOS, ICU LOS, and ICU intervention. RESULTS: There were no significant differences in morbidity or mortality between patients admitted to the vascular unit and those admitted to the ICU. Of patients evaluated prospectively, 129 (63%) were admitted directly to the vascular unit. Of the 73 patients admitted to the ICU, 63% required direct intervention compared with only 54% of patients in the retrospective series (P=0.001). In addition, after institution of the protocol, ICU LOS decreased significantly from 1.4 to 0.6 days (P<0.001). The hospital cost savings using this protocol averaged $1043 per patient. CONCLUSIONS: A clinical protocol can select patients for admission to the ICU or the vascular unit following CEA without increase in morbidity or mortality. Selective use of the ICU conserved resources, decreased ICU LOS, and provided substantial cost savings.

Aged↗
PubMed1997

Gastroesophageal tumor embolization to the popliteal arteries.

Arterial tumor embolization is an unusual cause of acute arterial occlusion and is reported primarily in the oncologic literature. We report a case of acute bilateral popliteal artery emboli from adenocarcinoma of the distal esophagus. Arterial tumor emboli are infrequent but should be considered in the differential diagnosis by the vascular surgeon caring for patients with malignancy.

Adenocarcinoma↗
PubMed1997

Asymptomatic carotid endarterectomy. Patient and surgeon selection.

BACKGROUND AND PURPOSE: The applicability of prospective carotid endarterectomy protocols to the general population has been questioned. Outcomes for asymptomatic patients undergoing carotid endarterectomy were compared with the results of the Asymptomatic Carotid Atherosclerosis Study (ACAS) patients treated concurrently at our institution. METHODS: Asymptomatic patients undergoing carotid endarterectomies (n = 277) from 1987 to 1993 (ACAS enrollment period) were reviewed. Primary end points were mortality, myocardial infarction, and stroke. Five subgroups were studied: (1) ACAS surgical patients; (2) ACAS-eligible patients not enrolled and ACAS surgeons; (3) ACAS-eligible patients not enrolled and non-ACAS surgeons; (4) ACAS-ineligible patients and ACAS surgeons; and (5) ACAS-ineligible patients and non-ACAS surgeons. RESULTS: ACAS-eligible patients were younger (P = .014), had more severe carotid stenosis (P = .001), and had lower incidences of pulmonary (P = .015) and renal (P = .008) diseases compared with ineligible patients. Patient selection (ACAS eligibility) significantly improved outcomes for mortality (P = .014) and myocardial infarction (P = .006). Length of stay favored ACAS-eligible patients (P = .004). ACAS surgeons operated on more severely stenotic carotid lesions (P = .005) and on patients with a lower incidence of coronary artery disease (P = .007). There was no difference in outcomes between ACAS and non-ACAS surgeons. CONCLUSIONS: Patient selection was a significant factor in determining outcome. With strict adherence to ACAS enrollment guidelines, the conclusions of ACAS appear applicable to patients seen at our institution with asymptomatic carotid stenosis.

Adult↗
PubMed1997

Ultrasonography in the diagnosis of acute appendicitis.

The purpose of this study was to assess our results of using graded compression ultrasonography (US) to confirm the diagnosis of acute appendicitis. Graded compression US was performed on 94 patients who presented at the Lehigh Valley Hospital, Allentown, Pennsylvania with an equivocal clinical picture of acute appendicitis. When used to diagnose acute appendicitis, US provided a specificity of 93.7%, sensitivity of 74.2%, and accuracy of 87.2%. We conclude that graded compression US was useful to rule out the diagnosis of acute appendicitis and helped to avoid unnecessary appendectomies and reduced negative laparotomies. Our results proved to be comparable to previously reported studies.

Acute Disease↗
PubMed1996

Role of magnetic resonance imaging in the diagnosis of osteomyelitis in diabetic foot infections.

PURPOSE: The role of magnetic resonance imaging (MRI) in the diagnosis of osteomyelitis in foot infections in diabetics was investigated. The accuracy, sensitivity, and specificity of MRI, plain radiography, and nuclear scanning were determined for diagnosing osteomyelitis, and a cost comparison was made. METHODS: Twenty-seven patients with diabetic foot infections were studied prospectively. All patients underwent MRI and plain radiography. Twenty-two patients had technetium bone scans, and 19 patients had Indium scans. Nineteen patients had all four tests performed. Patients with obvious gangrene or a fetid foot were excluded. RESULTS: The diagnosis of osteomyelitis was established by pathologic specimen (n = 18), bone culture (n = 3), or successful response to medical management (n = 6). Osteomyelitis was confirmed in nine of the pathologic specimens. The diagnostic sensitivity, specificity, and accuracy for MRI was 88%, 100%, and 95%, respectively, for plain radiography it was 22%, 94%, and 70%, respectively, for technetium bone scanning it was 50%, 50%, and 50%, respectively, and for Indium leukocyte scanning it was 33%, 69%, and 58%, respectively. The data were analyzed statistically with the two-tailed Fisher's exact test. MRI was the only test that was statistically significant (p < 0.01). CONCLUSIONS: MRI appeared to be the single best test for the diagnosis of osteomyelitis associated with diabetic foot infections. It had a better diagnostic accuracy than conventional modalities and appeared to be more cost-effective than the frequently used Indium scan.

Adult↗
PubMed1995

Carotid artery stenosis: preoperative noninvasive evaluation in a community hospital.

PURPOSE: The purpose of this study was to determine whether noninvasive evaluation with duplex ultrasonography and magnetic resonance angiography of patients with carotid artery stenosis can replace contrast angiography at our institution. METHODS: This study consisted of a retrospective chart review of 40 patients (74 carotid arteries) in combination with a blinded reanalysis of original data. Contrast angiography was compared with duplex ultrasonography and magnetic resonance angiography. The overall diagnostic accuracy of duplex ultrasonography and magnetic resonance angiography was determined individually and concordantly in patients being evaluated for carotid artery stenosis. RESULTS: The overall sensitivity of duplex ultrasonography was 88.5%, and the specificity was 91.7% (Spearman correlation coefficient = 0.8456; p < 0.001). For magnetic resonance angiography the sensitivity was 92.3%, and the specificity was 97.9% (Spearman correlation coefficient = 0.9086; p < 0.001). In the presence of concordance, the noninvasive studies exhibited a sensitivity of 100%, (correlation coefficient = 0.9661; kappa value = 0.9655). No occlusions or severe lesions were missed by both studies. In only one vessel (1.52%) was a false-positive concordance noted. CONCLUSIONS: Carotid endarterectomy may be undertaken with a high degree of confidence that the operation will be appropriate if the noninvasive evaluations are concordant. In the absence of concordance of the noninvasive studies, contrast angiography should be considered.

Aged↗
PubMed1994

Death and adverse cardiac events after carotid endarterectomy.

PURPOSE: This study evaluated operative mortality rate and adverse cardiac events after carotid endarterectomy. Efficacy of preoperative cardiac evaluation was studied and stroke mortality rate was determined. METHODS: This was a retrospective review of 562 patients undergoing carotid endarterectomy at a 740-bed community hospital. Data were analyzed with chi 2 analysis, logistic regression analysis, and Goldman criteria for cardiac risk. RESULTS: The mortality rate was 1.6% (nine patients). There were 10 myocardial infarctions (1.8%). Six of these (1.1%) were fatal. The Goldman Index allowed us to classify 530 patients in a low-risk group (Goldman classes I and II, operative mortality rate = 1.1%) and 32 patients in a high-risk group (Goldman classes III and IV, mortality rate = 9.4%). Independent risk variables were identified for myocardial infarction and overall operative death. These variables were then used to develop a probability model for prediction of operative death and adverse cardiac events. The stroke rate in the 562 patients was 0.7% (four patients). For the 345 patients with symptoms, the stroke rate was 0.6% (two patients); for the 217 symptom-free patients, it was 0.9% (two patients). The combined stroke mortality rate was 2.3%. For patients with symptoms, it was 2.9%; for symptom-free patients, it was 1.4%. CONCLUSIONS: Independent clinical variables can help determine patients at increased risk for perioperative myocardial infarction or operative death. Patients in Goldman classes III and IV are at increased risk for adverse events. Carotid surgery can be performed safely in our medical community.

Aged↗
PubMed1993

The cerebral hyperperfusion syndrome: diagnostic value of ocular pneumoplethysmography.

PURPOSE: There were two purposes to our study. The first was to characterize the ocular hyperperfusion associated with carotid endarterectomy. The second was to relate ocular hyperperfusion to the clinical presentation of cerebral hyperperfusion syndrome. METHODS: This was a retrospective chart review of 2331 patients who underwent carotid endarterectomy at our institution between June 1978 and May 1991. RESULTS: Twelve of these carotid endarterectomies were associated with ocular hyperperfusion on the side of operation. Clinical evidence of cerebral hyperperfusion syndrome was observed in five of these 12 procedures. In these five patients there were two associated fatal intracerebral hemorrhages and one permanent coma. In the latter three patients the contralateral internal carotid arteries were totally occluded. CONCLUSION: Ocular hyperperfusion, as documented with ocular pneumoplethysmography, is useful in alerting the physician to the potential for development of the cerebral hyperperfusion syndrome.

Air↗
PubMed1991

Free-tissue transfers for limb salvage utilizing in situ saphenous vein bypass conduit as the inflow.

Using vein grafts to bypass sclerotic and occluded arterial segments is a well-established technique in vascular surgery. For infrapopliteal bypass, autogenous veins have better patency rates than synthetic grafts. Although not resolved, in situ bypasses seem to be better than reversed bypasses, especially for "far away" segments. Although the etiology is not understood, it is a well-known clinical finding that sclerosis affects arteries more than the veins and, as a whole, is more advanced in lower extremities compared with the trunk and upper extremities. Our experience with eight patients in whom critical soft-tissue defects were covered with free-tissue transfers in severely compromised lower extremities utilizing the in situ saphenous vein bypass as the inflow is presented. Simultaneous bypass and free-tissue transfers were performed in seven and delayed free-tissue transfer was done in one. Follow-up ranged from 6 months to 3 years. To date, two patients underwent amputations. Five patients are able to maintain bipedal ambulation. One patient is wheelchair-bound with intact lower extremities. In well-selected patients, this procedure may offer an alternative treatment to amputation. However, because of the complexity of these combined procedures, we strongly urge careful patient selection.

Adult↗
PubMed1989

Duplex ultrasound and ocular pneumoplethysmography concordance in detecting severe carotid stenosis.

Concordance between two independent tests should serve to increase the accuracy of diagnosis. A combination of ocular pneumoplethysmography and duplex ultrasound, which uses high-resolution B-mode imaging plus spectral analysis, was used to evaluate 289 consecutive patients prior to biplane carotid angiography. Where there was concordance, the noninvasive tests predicted the presence or absence of hemodynamically severe carotid stenosis (75% or greater cross-sectional area reduction) with a sensitivity of 96.8%, a specificity of 95.9%, an accuracy of 96.2%, and positive and negative predictive values of 91.0% and 98.6%, respectively. Of the 538 study arteries, only four (0.74%) angiographically severe lesions escaped detection by both noninvasive tests. Sources of diagnostic error for both tests were defined. We believe that the combination of duplex ultrasound and ocular pneumoplethysmography significantly improves the overall assessment of carotid atherosclerosis.

Carotid Artery Diseases↗
PubMed1987

Accessory nerve injury during carotid endarterectomy.

Injury to the accessory nerve (cranial nerve XI) during carotid endarterectomy is rare; to date only three cases have been reported in the literature. Traction on the sternocleido-mastoid muscle was the proposed mechanism of injury in all three cases. Four cases of accessory nerve palsy occurred in 850 carotid endarterectomies performed between 1978 and 1986 at this institution, an incidence of 0.47%. All four patients had classic signs and symptoms of accessory nerve injury, which developed between 20 and 60 days after operation. The three most recent cases were examined specifically for accessory nerve injury in the immediate postoperative period and exhibited normal trapezius function. None had any other central nervous system dysfunction. Two of these patients regained full accessory nerve function and the most recent case is showing signs of reinnervation with conservative therapy. Isolated central nervous system and spontaneous accessory nerve palsies are exceptionally rare, and since any traction injury or transection should have been detected by postoperative examinations in three of four patients, we propose surgical scar formation as a mechanism of accessory nerve palsy after carotid endarterectomy. If such a palsy develops in the postoperative period, we recommend conservative therapy.

Accessory Nerve Injuries↗
PubMed1985

The frequent occurrence of false-positive results in phleborheography during pregnancy.

In this study, none of 25 pregnant women without any past history of venous thromboembolic disease had a positive phleborheogram sometime during their pregnancy or within six weeks post partum. In contrast, zero of ten nonpregnant women, also screened for venous thrombophlebitis, had a positive test finding during the same time interval. No clinical parameters, including weight gain, leg circumference, leg swelling, development of varicose veins, leg pain or use of support stockings, correlated with the occurrence of a positive test result. While there is conflicting evidence from other studies, our data suggest the need for caution in interpreting a positive phleboroheogram as an accurate indicator of thrombophlebitis in pregnant women.

Adult↗
PubMed1984

Treatment of renal artery embolism.

Renal artery embolectomy was performed on four patients. There was no operative mortality. Four of the five affected kidneys were salvaged. The most common initial symptom was flank pain. The literature from 1970 to 1982 was reviewed to determine the current operative mortality (11%) and frequency of kidney salvage (67% to 90%) with surgery or anticoagulation. Newer treatment modalities, including intraarterially injected low-dose streptokinase and percutaneous transluminal angioplasty, have also proved useful. The addition of these newer methods, combined with the fact that kidneys can frequently be salvaged after prolonged periods of acute renal artery occlusion, led to the development of a clinical algorithm for treatment. With this algorithm, surgical embolectomy was reserved for patients with total renal parenchymal compromise caused by emboli, whose conditions failed to respond to less invasive treatment modes.

Adult↗
PubMed1984

Dazoxiben, a thromboxane synthetase inhibitor, in Raynaud's phenomenon.

Dazoxiben, a specific thromboxane synthetase inhibitor, was evaluated in 21 patients with Raynaud's phenomenon in a double-blind, placebo-controlled crossover experiment. Total fingertip blood flows were measured by plethysmography and capillary blood flows were measured by 133Xe disappearance rate. Subjects were studied in both a warm (28 degrees) and a cold (20 degrees) room. Arteriovenous (AV) shunt flow was estimated by subtraction of capillary flow from total flow. Ex vivo production of thromboxane B2 (TXB2) and 6-keto PGF1 alpha was determined by specific radioimmunoassay in serum from venous blood incubated for 1 hr (37 degrees). Plasma concentrations of TXB2 and 6-keto PGF1 alpha were also monitored. Dazoxiben (100 mg 4 times a day for 14 days) inhibited ex vivo TXB2 production (from 463.1 +/- 69.9 to 101.8 +/- 13.4 ng/ml/hr; (means +/- SE], enhanced ex vivo 6-keto PGF1 alpha production (from 1.38 +/- 0.05 to 3.76 +/- 0.18 ng/ml/hr), reduced plasma TXB2 concentration (from 88.1 +/- 13.9 to 38.8 +/- 5.9 pg/ml). There were no changes in plasma concentration of 6-keto PGF1 alpha. Dazoxiben did not improve total digital blood flow, capillary flow, AV shunt flow, or forearm blood flow at 28 degrees or 20 degrees. There was no subjective improvement in frequency or severity of Raynaud's attacks (assessed by patient diaries). It is concluded that dazoxiben is a potent and specific thromboxane synthetase inhibitor capable of altering arachidonic acid metabolism, but is of little or no benefit in the treatment of Raynaud's phenomenon.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

An unusual complication of bypassed popliteal aneurysms.

The most common treatment of popliteal aneurysms is bypass and in situ ligation of the aneurysm. Two patients treated in this manner continued to have enlargement of their aneurysms, with symptomatic vein and nerve compression in the popliteal space. The aneurysms persisted because of failure to ligate arterial branches arising from the aneurysm itself. These recurrences were treated successfully by ligating the branches from within the aneurysm and obliterating the aneurysmal sac.

Aneurysm↗