New methods for time-resolved fluorescence spectroscopy data analysis based on the Laguerre expansion technique--applications in tissue diagnosis.

OBJECTIVES: A new deconvolution method for the analysis of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data is introduced and applied for tissue diagnosis. METHOD: The intrinsic TR-LIFS decays are expanded on a Laguerre basis, and the computed Laguerre expansion coefficients (LEC) are used to characterize the sample fluorescence emission. The method was applied for the diagnosis of atherosclerotic vulnerable plaques. RESULTS: At a first stage, using a rabbit atherosclerotic model, 73 TR-LIFS in-vivo measurements from the normal and atherosclerotic aorta segments of eight rabbits were taken. The Laguerre deconvolution technique was able to accurately deconvolve the TR-LIFS measurements. More interesting, the LEC reflected the changes in the arterial biochemical composition and provided discrimination of lesions rich in macrophages/foam-cells with high sensitivity (> 85%) and specificity (> 95%). At a second stage, 348 TR-LIFS measurements were obtained from the explanted carotid arteries of 30 patients. Lesions with significant inflammatory cells (macrophages/foam-cells and lymphocytes) were detected with high sensitivity (> 80%) and specificity (> 90%), using LEC-based classifiers. CONCLUSION: This study has demonstrated the potential of using TR-LIFS information by means of LEC for in vivo tissue diagnosis, and specifically for detecting inflammation in atherosclerotic lesions, a key marker of plaque vulnerability.

Yield of repeated screening for abdominal aortic aneurysm after a 4-year interval. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators.

BACKGROUND: Little is known about the rate at which new abdominal aortic aneurysms (AAAs) develop or whether screening older men for AAA, if undertaken, should be limited to once in a lifetime or repeated at intervals. METHODS: A large population of veterans, aged 50 through 79 years, completed a questionnaire and underwent ultrasound screening for AAA. Of these, 5151 without AAA on the initial ultrasound (defined as infrarenal aortic diameter of 3.0 cm or larger) were selected randomly to be invited for a second ultrasound screening after an interval of 4 years. Local records and national databases were searched to identify deaths and AAA diagnoses made during the study interval in subjects who did not attend the rescreening. RESULTS: Of the 5151 subjects selected for a second screening, 598 (11.6%) had died (none due to AAA), and 20 (0.4%) had an interim diagnosis of AAA. A second screening was performed on 2622 (50.9%), of whom 58 (2.2%; 95% confidence interval, 1.6%-2.8%) had new AAA. Three new AAAs were 4.0 to 4.9 cm, 10 were 3.5 to 3.9 cm, and 45 were 3.0 to 3.4 cm. Independent predictors of new AAA at the second screening included current smoker (odds ratio, 3.09; 95% confidence, 1.74-5.50), coronary artery disease (odds ratio, 1.81; 95% confidence interval, 1.07-3.07), and, in a separate model using a composite variable, any atherosclerosis (odds ratio, 1.97; 95% confidence interval, 1.16-3.35). Adding the interim and rescreening diagnosis rates suggests a 4-year incidence rate of 2.6%. Rescreening only in subjects with infrarenal aortic diameter of 2.5 cm or greater on the initial ultrasound would have missed more than two thirds of the new AAAs. CONCLUSIONS: A second screening is of little practical value after 4 years, mainly because the AAAs detected are small. However, the incidence that we observed suggests that a second screening after longer intervals (ie, more than 8 years) may provide yields similar to those seen in initial screening and therefore warrants further study.

The value of postoperative fever evaluation.

Evaluation of fever in the early postoperative period often includes a battery of diagnostic tests to determine the source of or to exclude a serious infection. In order to evaluate the clinical usefulness and cost effectiveness of the information obtained from these tests, the data for 464 patients who had undergone abdominal operation were reviewed. Of the 464 patients, 71 (15%) fulfilled the criterion of fever with rectal temperature of 38.5 degrees C or greater in the first 6 postoperative days. For 27% (19/71) of the patients with a postoperative fever, culture-proven infection was responsible for the fever. For 74% (14/19) of the patients with infection, the correct diagnosis was made based on clinical findings and confirmed by a single appropriate test. The remaining five patients with infection were diagnosed via a battery of test because of the absence of clinical findings indicating the source of their infection. Rote ordering of unnecessary tests resulted in an excess expenditure of $19,738, or $278 per febrile patient. We conclude that routine evaluations of fever do not alter the outcome of the majority of patients and are not cost effective.

Topical versus systemic cephalosporin administration in elective biliary operations.

The role of prophylactic antibiotic lavage in elective biliary tract operations is controversial. To investigate this question, a prospective, randomized study was undertaken between 1979 and 1983. All patients more than 18 years of age who underwent elective biliary operations were included. Eighty-eight patients were enrolled in the study and were stratified into the following antibiotic groups: (1) cefamandole nafate 2 gm administered intravenously preoperatively and 6 hours postoperatively in four doses; (2) cefamandole nafate 0.4% solution: 250 ml to irrigate the abdominal wound on opening, 500 ml to irrigate the peritoneal cavity, and 250 ml to irrigate the wound on closing; and (3) systemic plus topical administrations as in Nos. 1 and 2. Age, sex, type of operation, and underlying diseases were comparable in all groups. The patients were then evaluated for postoperative infections. In the intravenous cefamandole group there was only one patient who developed a urinary tract infection after operation. In the topical cefamandole group there were four postoperative infections: wound-one, urinary tract--two, and cholangitis--one. In the intravenous plus topical cefamandole group there were four postoperative infections: wound--one, urinary tract--two, and pneumonia--one. No deaths occurred in any group. Blood, subcutaneous, and peritoneal drug levels were sampled 1 hour after opening and before closing. Therapeutic serum levels of cefamandole are 1 to 16 micrograms/ml and adequate serum levels were achieved in all groups. However, higher levels were obtained in the subcutaneous tissue and peritoneum when topical cefamandole was used. We conclude: (1) Topical cefamandole lavage alone is adequate prophylaxis in elective biliary operations and achieves comparable results as perioperative systemic administration; (2) topical cefamandole resulted in higher subcutaneous tissue and peritoneal levels than intravenous cefamandole and also achieved therapeutic serum levels; and (3) there is no advantage to the use of systemic plus topical antibiotics in elective biliary operations.

Effect of the duration of symptoms, transport time, and length of emergency room stay on morbidity and mortality in patients with ruptured abdominal aortic aneurysms.

BACKGROUND: Despite improvements in emergency medical services, surgical technology, and postoperative critical care, ruptured abdominal aortic aneurysm (AAA) is associated with constantly high morbidity and mortality. To determine the effect of the duration of symptoms, transport time to hospital, and length of emergency department assessment on outcome, we evaluated 124 consecutive patients with ruptured AAA treated during the past decade. METHODS: The medical records for 122 patients were abstracted for preoperative hypotension, cardiopulmonary resuscitation (CPR), blood loss, and three time intervals: symptom onset to operation, transport time to hospital, and emergency department assessment. RESULTS: Intraoperative mortality was 26% (n = 32), 30-day mortality was 51% (n = 63), and cumulative hospital mortality was 56% (n = 69). Death occurred in 52 (64%) of 81 patients with hypotension compared with 14 (35%) of 40 patients without hypotension (p < or = 0.01). Hypotension was present in 37 (82%) of 45 patients who arrived in the operating room in 2 hours or less compared with 26 (60%) of the 43 patients who arrived later than 2 hours (p < or = 0.05). Death followed in 21 (91%) of 23 patients who received CPR compared with 46 (46%) of 99 patients who did not receive CPR (p < or = 0.01). Bowel ischemia was observed in 18 (30%) of 60 patients who received more than 10 units of blood compared with 3 (5%) of 61 patients who received 10 units or less (p < or = 0.01). CONCLUSIONS: For patients with ruptured AAA, prolonged presurgical time was associated with a more hemodynamically stable patient and a lower mortality. Progressive bleeding in those hemodynamically stable patients was reflected by a larger blood transfusion requirement. Such patients exhibited an increased incidence of ischemic bowel complications, perhaps caused by splanchnic arterial ischemia augmented by preexisting atherosclerosis, as well as extrinsic compression by mesenteric hematomas.

Analysis of the transition to percutaneous placement of Greenfield filters.

To establish whether a transition from surgical to percutaneous placement of Greenfield filters was justified, a review of the safety, efficacy, and cost-effectiveness of the two approaches was conducted. Between 1984 and 1989, 168 filters were placed in 169 patients, 48 surgically and 120 percutaneously. Placement was successful in 45 (94%) of the 48 surgical patients and 120 (99%) of the 121 percutaneous patients. Filter misplacement occurred in three (6%) surgical patients and no percutaneous patients. Clinically evident femoral vein thrombosis occurred in only four (5%) of the percutaneous patients, while inferior vena cava thrombosis occurred in three (3%) of the percutaneous patients. One pulmonary embolus occurred after percutaneous filter placement and resulted in death. The cost of percutaneous placement was 58% that of surgical placement. A retrospective review of the experience in our patient population indicates that safety, cost, and ease of insertion make the percutaneous approach the procedure of choice for Greenfield filter placement.

Female surgeons in the 1990s. Academic role models.

As part of a larger survey of the membership of the Association of Women Surgeons, data were collected to characterize the participation of women in academic surgery and surgical education. Of the 1500 members, 676 (45%) responded, and 318 of these respondents held a faculty appointment. Two hundred thirty-nine of the respondents' practices were based in a university or university-affiliated hospital. This sample was biased toward more academically motivated, upwardly mobile surgeons. Two hundred thirty-six of the respondents believed policies relating to tenure are unfair to women. Four hundred fifty-three respondents reported having role models at some point in their career, half of whom were men. However, only 204 still had access to role models or mentors at the time of the survey. Six hundred thirty respondents believed that female medical students need successful female surgeons as role models.

Treatment of necrotizing soft tissue infections. The need for a new approach.

Necrotizing soft tissue infections are classified by the type of infecting organism, the presenting clinical picture, and the treatment required. However, reliance on this schema is impractical since it often leads to an inordinate delay in appropriate surgical therapy with an unwarranted loss of a limb or life. Since 1958, 21 patients were treated at the UCLA Medical Center with necrotizing soft tissue infections. Unifocal ulcerations and nonspreading infections were excluded. Of the 21 patients, the initial classification of the infections included necrotizing fasciitis in 38 percent, clostridial gangrene in 38 percent, bacterial synergistic gangrene in 19 percent, and streptococcal hemolytic gangrene in 5 percent. Diabetes or evidence of immunosuppression was found in 71 percent of the patients. The course could be traced to either a perforated viscus in 43 percent or a traumatic injury in 43 percent. No single clinical sign, including tissue gas, was diagnostic for a specific type of necrotizing soft tissue infection. Culture revealed a polymicrobial flora in 76 percent. Overall mortality was 52 percent and the amputation rate was 36 percent. Mean time to appropriate surgical therapy was 1.9 days. Operations performed more than 24 hours after recognition of infection resulted in a 70 percent mortality versus a 36 percent mortality when operations were performed less than 24 hours after recognition. A lesser operation to conserve tissue resulted in a 71 percent mortality versus a 43 percent mortality with initial radical surgery which encompassed all devitalized tissue. Based on these data, we conclude that classification of necrotizing soft tissue infections should be simplified to clostridial and nonclostridial infections. Radical operative debridement, regardless of tissue loss, should be carried out immediately after fluid resuscitation, and antibiotic coverage must be broad spectrum from the time of onset due to the polymicrobial nature of these infections.

Production of endothelium-derived relaxing factor (EDRF) is compromised after ischemia and reperfusion.

Rabbit hind limbs were subjected to 5 hours of ischemia with or without 1 hour of in vivo reperfusion, and the response of femoral artery segments to vasocontrictors and vasodilators was studied in vitro. The ability of endothelium-derived relaxing factor (EDRF)-dependent vasodilators to relax arterial segments was not altered after up to 5 hours of ischemia alone but was significantly decreased after 4 hours of ischemia if followed by 1 hour of in vivo reperfusion. Thus, we concluded that a specific injury occurs to endothelial cells after ischemia-reperfusion, which occurs solely during the reperfusion period.

Peritoneal dialysis: an increasingly popular option.

Vascular surgeons well versed in peritoneal dialysis applications understand the importance of this modality among the limited options afforded to patients in renal failure. Peritoneal and hemodialysis strategies are interdependent and should be considered in concert. Careful assessment often shows that patients with diminishing vascular access have been overlooked as viable peritoneal dialysis candidates. This chapter summarizes peritoneal dialysis in terms of its history, physiological principles, indications, contraindications, catheter placement, types of administration, and the identification and management of complications.

Carotid artery disease in patients with head and neck carcinoma.

Irradiation has been shown experimentally to cause accelerated development of atherosclerosis in exposed large arteries. However, occurrence of such an entity in carotid arteries of patients after treatment for head and neck carcinoma is unknown. Therefore, we reviewed 179 patient charts who had undergone head and neck operations with or without irradiation between 1979-1987. Of these 179 patients, 107 (59.8%) were dead at time of follow-up. Cause of death was unknown in 42 (40%) patients; in the remainder included: respiratory arrest--33; carcinoma-related--18; cardiac--6;pneumonia--7; and trauma--1. Average interval from treatment to death was 23.5 months. Of the 72 patients known to be alive, follow-up was obtained in 52 patients. Their average age was 64.9 years. Risk factors for atherosclerosis included: male gender--43; smoking--50; hypertension--9; diabetes--4; coronary artery disease--12; and peripheral vascular disease--4. Seventy-five per cent of these patients received postoperative irradiation. Average follow-up was 64.5 months. Duplex scans were performed on 34 patients. Three patients had common or internal carotid stenoses greater than 75 per cent. All of these patients had received irradiation and none of them were symptomatic. Seven patients had carotid stenoses between 50 to 75 per cent; five of these had received irradiation. Of these five patients, one had a stroke 60 months postoperatively, and one had a TIA 36 months postoperatively. The remaining 58 patients (of which 48 had irradiation) had carotid stenoses less than 50 per cent and none were symptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Unilateral upper extremity edema. A case report.

A case report of a 28-year-old Hispanic male with a 5-month history of left arm, face and supraclavicular edema is presented. Chest radiography revealed bilateral pleural effusions. Thoracentesis was negative for malignant cells. Left arm venogram demonstrated compression of the left subclavian vein and lymphangiogram was consistent with perilymphatic stasis. Computerized tomography and magnetic resonance imaging demonstrated a questionable mass in the left side of the neck. On exploration of the left supraclavicular fossa, a severely fibrotic thoracic duct was encountered as well as a prominent scalene lymph node. Pathological section revealed an adenocarcinoma in both specimens which was positive for keratin and carcinoembryonic antigen. Chemotherapy was begun, however, the patient died 3 months later secondary to a respiratory arrest. This presentation of an adenocarcinoma arising from an unknown gastrointestinal source is unusual. A search should be made to locate the primary site. Prognosis is unclear but presumed poor due to the rarity of this presentation.

Determinants of failure in superficial femoral artery angioplasty.

Although results of iliac artery balloon angioplasty have been shown to be good, there are much less data regarding initial success and durability of superficial femoral artery (SFA) dilation. The authors retrospectively reviewed the results of 22 patients treated for 27 SFA lesions between 1981 and 1986. Mean age was 64.5 years (fifty-five to seventy-six). Results were analyzed with respect to initial, early (< twelve months), and late (> twelve months) angiographic and clinical success. Indications were claudication (22), nonhealing ulcer (3), and rest pain (2). Mean follow-up was 30.9 months; 100% at one year and 92% at two years. Initial failure occurred in 9 (33%) lesions. There were 2 early and 2 late failures for a cumulative patency rate of 90.3% and 78% at one and two years, respectively. Predictors of clinical failure were: (1) initial--age, SFA occlusion, and angioplasty rating; (2) early--age, SFA occlusion, degree of atherosclerosis, and angioplasty rating; (3) late--angioplasty rating. There were 3 complications (11%). The authors conclude that: (1) 33% of attempted SFA angioplasties were initially unsuccessful and that the cumulative patency rate was 78% at two years. (2) Age is predictive of initial and early failure; SFA occlusion, of initial and early failure; degree of atherosclerosis, of early failure; and angioplasty appearance, of initial, early, and late failures. (3) Complications did not result in limb loss or require surgery.

Diagnosis of vulnerable atherosclerotic plaques by time-resolved fluorescence spectroscopy and ultrasound imaging.

In this study, time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) and ultrasonography were applied to detect vulnerable (high-risk) atherosclerotic plaque. A total of 813 TR-LIFS measurements were taken from carotid plaques of 65 patients, and subsequently analyzed using the Laguerre deconvolution technique. The investigated spots were classified by histopathology as thin, fibrotic, calcified, low-inflamed, inflamed and necrotic lesions. Spectral and time-resolved parameters (normalized intensity values and Laguerre expansion coefficients) were extracted from the TR-LIFS data. Feature selection for classification was performed by either analysis of variance (ANOVA) or principal component analysis (PCA). A stepwise linear discriminant analysis algorithm was developed for detecting inflamed and necrotic lesion, representing the most vulnerable plaques. These vulnerable plaques were detected with high sensitivity (>80%) and specificity (>90%). Ultrasound (US) imaging was obtained in 4 carotid plaques in addition to TR-LIFS examination. Preliminary results indicate that US provides important structural information of the plaques that could be combined with the compositional information obtained by TR-LIFS, to obtain a more accurate diagnosis of vulnerable atherosclerotic plaque.

Application of the laguerre deconvolution method for time-resolved fluorescence spectroscopy to the characterization of atherosclerotic plaques.

This study investigates the ability of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) to detect inflammation in atherosclerotic lesion, a key feature of plaque vulnerability. A total of 348 TR-LIFS measurements were taken from carotid plaques of 30 patients, and subsequently analyzed using the Laguerre deconvolution technique. The investigated spots were classified as Early, Fibrotic/Calcified or Inflamed lesions. A stepwise linear discriminant analysis algorithm was developed using spectral and TR features (normalized intensity values and Laguerre expansion coefficients at discrete emission wavelengths, respectively). Features from only three emission wavelengths (390, 450 and 500 nm) were used in the classifier. The Inflamed lesions were discriminated with sensitivity > 80% and specificity > 90 %, when the Laguerre expansion coefficients were included in the feature space. These results indicate that TR-LIFS information derived from the Laguerre expansion coefficients at few selected emission wavelengths can discriminate inflammation in atherosclerotic plaques. We believe that TR-LIFS derived Laguerre expansion coefficients can provide a valuable additional dimension for the detection of vulnerable plaques.

Clinical experience with a collagen-impregnated knitted Dacron vascular graft.

This report describes our first clinical experience with collagen-impregnated Dacron grafts in the aortic position. Fifty-four consecutive patients (43 men and 11 women), average age 67.5 years (44-84), received 11 tube grafts and 23 bifurcated grafts for abdominal aortic aneurysm replacement, 17 bifurcated grafts for aortic occlusive disease, two grafts for aortic pseudoaneurysm, and one graft for thoracoabdominal aneurysm repair. No preclotting maneuvers were used and there was no blood leak from the fabric upon restoration of blood flow, in spite of the use of systemic heparin. The hospital transfusion rate averaged 1.2 units in patients with occlusive disease and 2.7 units in patients undergoing aneurysm resection, which were similar to the transfusion rate in patients receiving standard knitted grafts prior to this study. There were two postoperative deaths from a myocardial infarction and a cerebral hemorrhage and no perioperative thromboembolic events. During a follow-up averaging 41.5 months (26-59), there were two late graft limb thromboses secondary to outflow disease progression. One patient died of aspiration two months postoperatively. Four patients died secondary to cardiac disease in at 13 and 21 months with functioning grafts. The rest of the patients are alive with functioning grafts. We conclude that the collagen-impregnated Dacron graft obviates the need for preclotting maneuvers because of a zero functional porosity.

An unusual cause of transient ischemic attacks: case report.

A 42-year-old black man, a physician, presented with a three week history of intermittent right arm and leg numbness and weakness, lasting about five minutes. This was not associated with headache, visual changes, seizures, aphasia or loss of consciousness. There was no history of head trauma, migraines, or previous attacks. Positive findings on physical examination were confined to a blood pressure of 182/80; evidence of hypertensive retinopathy; normal carotid pulses without bruits; and a Grade II/VI systolic ejection murmur with normal sinus rhythm. Initial hematocrit was 25.7%; white blood cell count 14,000 cu/mm with a normal differential; platelet count 532,000 cu/mm. An electrocardiogram showed left ventricular hypertrophy. Duplex scan demonstrated normal carotid bifurcations bilaterally, and arteriogram revealed no carotid or intracranial pathology. Hemoglobin electrophoresis revealed sickle cell disease of the SS type. He was treated with transfusion therapy and has remained asymptomatic at 40 months. Approximately 20% of children with the SS type sickle cell disease will have cerebrovascular symptoms caused by small intracranial artery occlusion due to sludging of the abnormal hemoglobin. This unusual cause of transient ischemic attacks can occur in older patients of African-American ancestry and must be recognized to enable early and effective therapy with exchange transfusion.

Superoxide anion release (O2-) after ischemia and reperfusion.

Neutrophils have been implicated as mediators of the reperfusion injury following ischemia. In order to measure neutrophil activation, O2- was determined after 2 hr of ischemia followed by 1 hr of reperfusion (no clinical reperfusion injury) and 3 hr of ischemia followed by 1 hr of reperfusion (significant clinical reperfusion injury). Using New Zealand white rabbits, baseline blood samples were drawn from an ear artery. The right iliac and femoral arteries were exposed and clamped. Just prior to clamp release, blood was obtained from the right iliac vein (ischemia). After 1 hr of reperfusion, blood was again taken from the right iliac vein (reperfusion). Neutrophils were isolated from the blood samples. O2- was determined by the reduction of cytochrome c using a spectrophotometer. In the 2-hr group, results (expressed as mumole O2-/min/2 x 10(6) cells) were: baseline, 0.337 +/- 0.025; ischemia, 0.512 +/- 0.039;* and reperfusion, 0.634 +/- 0.064*. (*P less than .05 as compared to baseline). In the 3-hr group, results were: baseline, 0.391 +/- 0.038; ischemia, 0.413 +/- 0.051; and reperfusion, 0.258 +/- 0.043** (**P less than 0.05 as compared to 2 hr reperfusion). A significant increase in O2- was seen after 2 hr of ischemia followed by 1 hr of reperfusion. However, little O2- increase was seen after 3 hr of ischemia and a significant O2- decrease was seen after 1 hr of reperfusion. We conclude: (1) Neutrophil O2- is stimulated early in ischemia followed by reperfusion; (2) after reperfusion injury occurs (3 hr), neutrophils have been activated and O2- can no longer be stimulated; and (3) O2- in this model may be involved in the clinical reperfusion injury seen.

Neutrophil (PMN) phagocytosis and chemotaxis after 2 hr of ischemia.

The role of PMN in the reperfusion injury after ischemia is unclear. It was the purpose of this study to determine if PMN functions of phagocytosis and chemotaxis were altered after a brief period of ischemia (2 hr) followed by reperfusion (1 hr) in a model where no significant reperfusion injury occurred. Baseline blood samples were drawn from an ear artery from New Zealand white rabbits for PMN and serum. The right iliac and femoral arteries were clamped for 2 hr. Just prior to clamp release, blood was harvested from the right iliac vein. After 1 hr of reperfusion, blood was again harvested from the right iliac vein. Phagocytosis was measured by the percentage ingestion of zymosan by PMN. The zymosan beads had been opsonized wtih baseline (b) (b), ischemia (i), or reperfusion (r) serum. Chemotaxis was evaluated by the number of PMN migrating across a filter. Serum obtained from b, i, and r blood samples served as the chemoattractants. Results for phagocytosis demonstrated a significant increase in i and r PMN as compared to b PMN. Opsonization by b,i, or r serum did not enhance this effect (ANOVA, F = 4.477; P = 0.0266). Similar increases in chemotaxis were observed for i and r PMN which also were not enhanced by the chemoattractants of b, i, or r serum (ANOVA, F = 25.43; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)