Is Paterson

Ultrasonographic screening for abdominal aortic aneurysm in an urban community

As part of the Birmingham Community Aneurysm Screening Project, 3500 men aged 65-75 years from 20 urban general practices were invited for aortic ultrasonographic screening at their own general practitioners surgery; 2669 (76.3 per cent) attended. Compliance rates varied between catchment areas, from 52.1 per cent for inner-city areas to 89.6 per cent for suburbs. Successful aortic imaging was achieved in 97.3 per cent of scans. Aortic diameter > 29 mm occurred in 219 patients (8.4 per cent) and 79 (3.0 per cent) with a diameter > 40 mm were referred for vascular surgical assessment; 140 patients with an aortic diameter of 29-40 mm are currently undergoing follow-up by serial ultrasonographic examinations at intervals of 3 months at their doctors surgery. Risk factor analysis revealed ischaemic heart disease in 21.9 per cent of men with aneurysm, compared with 11.6 per cent in those without (P < 0.001); 18.3 per cent of men with aneurysm had had a previous myocardial infarction and 13.2 per cent had peripheral vascular disease, compared with 7.4 per cent (P < 0.001) and 8.0 per cent (P < 0.01) respectively of those without. No association was found between aneurysm and hypertension or diabetes. Community-based aortic screening is an inexpensive, effective method of diagnosis of aneurysm, with high compliance from the at-risk cohort of an urban population. Such screening programmes may help to reduce the mortality rate from aortic aneurysm rupture.

Microproteinuria predicts the severity of systemic effects of reperfusion injury following infrarenal aortic aneurysm surgery

Noncardiogenic pulmonary dysfunction can be demonstrated in all patients following elective aortic aneurysm repair and is a cause of postoperative morbidity. Aortic clamping and reperfusion initiate a systemic inflammatory response producing endothelial damage and increases in vascular permeability. In the lung this is manifest as pulmonary edema and in the kidney as detectable increases in urinary protein excretion (microproteinuria). Immunoassay of low-level protein excretion appears to provide an index of the systemic effects of local reperfusion injury and may allow early prediction of complications such as pulmonary edema. Hourly urinary albumin and IgG excretion was measured in 40 patients undergoing infrarenal aortic aneurysm repair and expressed as ratios to urinary creatinine (albumin/creatinine ratio [ACR] and IgG/creatinine ratio [IgGCR]). These were compared to clinical outcome. Pulmonary dysfunction was assessed according to Pao2∶Fio2 ratios and chest radiography. Within 180 minutes of beginning surgery all patients had significant increases in ACR and IgGCR. Ten patients who manifested respiratory dysfunction had significantly higher ACRs at 4 hours (median 84.8, 95% confidence intervals, range 47.7 to 136) than patients who made uneventful recoveries (median 16.6, 95% confidence intervals, range 7.9 to 31.7). IgGCR increases paralleled that of ACRs. Differences persisted for 24 hours. Urinary protein excretion rises rapidly during aortic surgery. The degree of increase appears to predict development of pulmonary dysfunction. This simple test may provide a rational basis for evaluation of therapeutic modalities to limit reperfusion injury in these patients.

Reperfusion Plasma Contains a Neutrophil Activator

Aortic aneurysm repair produces inflammatory mediators, neutrophil activation, and remote organ injury. Reperfusion plasma from these patients produces microvascular injury in an ex vivo chemotactic model. This study investigates the mechanism of this injury. Vena caval blood was obtained before and 15 minutes after aortic clamp removal (n=16) or at laparotomy (n=10). Plasma or saline solution was introduced into unit dose chambers fixed atop dermabrasions on the back of depilated anesthetized rabbits. Animals were treated with intravenous saline solution (n=4); made neutropenic with nitrogen mustard (n=4); pretreated with the xanthine oxidase inhibitor allopurinol (n=4); or cotreated intravenously with the free radical scavengers superoxide dismutase (SOD) and catalase (n=4). Three hours later neutrophil counts (polymorphonuclear cells [PMN]/mm3) and activity (free radical production by flow cytometry), protein leakage, and inflammatory mediators (thromboxane [TX] and leukotriene B4[LTB4]) were measured. In contrast to control plasma in untreated rabbits, reperfusion plasma produced TX and LTB4 generation (1090±105 and 794±91 pg/ml, respectively,p<0.01), PMN accumulation (1636±210/mm3,p<0.01) and activation (276±31 mean fluorescent units), and microvascular permeability (554±90 µg/ml,p<0.01). Neutropenia (3±1 PMN/mm3) and cotreatment with SOD and catalase abolished these responses, whereas pretreatment with allopurinol did not. Human reperfusion plasma contains a soluble factor that stimulates free radical generation by rabbit neutrophils to produce a microvascular injury characterized by de novo TX production, neutrophil accumulation and activation, and increased microvascular permeability to protein.

Adjuvant Prostanoid Treatment During Femorodistal Reconstruction

A prospective randomized placebo-controlled trial was conducted to determine the effects of the stable prostacyclin analogue iloprost on early graft patency and hemodynamic parameters during femorodistal reconstruction for critical leg ischemia. Peripheral resistance and graft blood flow were measured using an operative Doppler flowmeter and graft pressure transducer. Postoperative graft surveillance was continued at 1-month and then at 3-month intervals by duplex Doppler ultrasonography, measurement of ankle-brachial pressure indices, and intravenous digital subtraction angiography when indicated. In patients receiving 3000 ng of iloprost (n=45) infused into the graft on completion there was an immediate mean decrease in peripheral resistance of 44% that persisted to skin closure in comparison with controls (n=38) in whom no such decrease in resistance occurred (p<0.001, Wilcoxon test). During the same period, mean graft blood flow increased in iloprost-treated patients by 74.5% compared with controls in whom there was a 6% increase in flow (p<0.001). Primary cumulative patencies at 1 month were significantly higher in iloprost-treated grafts, 98% compared to 83% for controls (p<0.05, log-rank test). Cumulative primary patencies at 1 year and secondary patencies at 1 month and 1 year were also greater in the iloprost-treated group (67%, 98%, and 87.6%, respectively) compared to controls (65%, 86%, and 79.3%, respectively), but these did not achieve statistical significance. A single bolus infusion of iloprost has prolonged beneficial effects on graft blood flow and peripheral resistance during femorodistal reconstruction. This is reflected by improved early primary graft patencies. Prostacyclin analogues may prove to be a valuable adjunctive treatment during distal vascular reconstruction. These results provide a rationale for further investigations into modes of administration and clinical usage.