| 1. |
- Acosta, Stefan, 1967-
(författare)
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On Acute Thrombo-Embolic Occlusion of the Superior Mesenteric Artery
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acute thrombo-embolic occlusion of the superior mesenteric artery (SMA) with intestinal infarction is a lethal disease, difficult to diagnose in time, with unknown incidence and cause-specific mortality. The aim of this thesis was to characterize the disease and to develop diagnostic methods. Two laboratory studies were conducted on patients with suspected acute SMA occlusion. A pilot-study showed that the fibrinolytic marker D-dimer was elevated in six patients with the disease. In the subsequent study including 101 patients, D-dimer was the only elevated coagulation marker in nine patients with the disease. In a prospective study 24 patients (median age 84 years) were identified, of whom four were diagnosed at autopsy, despite an autopsy-rate of 10%. One-fourth were initially nursed in non-surgical wards. Length of the intestinal infarction was a predictor for death. An analysis of patients from the three studies showed that D-Dimer was elevated in all 16 tested patients with the disease.Sixty patients with acute SMA occlusion underwent intestinal revascularisation and were registered in the Swedish Vascular Registry (SWEDVASC). One-year survival-rate was 40%. Previous vascular surgery was a negative risk-factor.A population-based study was conducted in Malmö, based on an autopsy-rate of 87%. Among 270 patients with the disease, 2/3 were diagnosed only at autopsy and 1/2 were managed in non-surgical wards. The incidence was 8.6 per 100000 person years. The age-standardized incidence increased exponentially without gender differences. The diagnosis was the cause of death in 1.2% among octogenarians and beyond. Thrombotic occlusions were located proximally within the SMA and associated with extensive intestinal infarctions. Synchronous embolism, often multiple, occurred in 2/3 of the patients with embolic occlusions.Conclusions: A normal D-dimer at presentation most likely excludes the diagnosis. Acute SMA occlusion was more frequent than previously estimated from clinical series. The patients were often nursed in non-surgical wards.
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| 2. |
- Björck, Martin
(författare)
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On intestinal ischaemia after aortoiliac surgery : Epidemiological, clinical and experimental studies
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An important cause of death among patients undergoing surgery of the abdominal aorta is intestinal ischaemia. In the Swedish Vascular Registry 2930 aortoiliac operations were identified. The complication was studied in a combined cohort and case-control study, and multivariate analysis performed. The incidence of intestinal ischaemia was 2.8% overall, 1.1% after elective surgery and 7.3% after shock for a ruptured abdominal aortic aneurysm (AAA). One-fourth of the patients who died after operation on aruptured AAA, and one-tenth of those who died after operation for other indications, suffered intestinal ischaemia. The cardinal symptoms and signs of early, bloody diarrhea and peritonitis were often absent. Sigmoidoscopy was potentially diagnostic in 95% of cases. Important risk factors for the complication were preoperative shock or renal insufficiency, emergency surgery, ligation of one or both internal iliac arteries, aortobifemoral grafting, prolonged operation or cross-clamping time and operation at aregional hospital.In a clinical study on 34 patients, sigmoid colon intramucosal pH (pHi) was diagnostic for ischaemic colitis with both sensitivity and specificity of 100% when <6.86 for >4 hours, and for death or life-threatening complications with sensitivity 100% and specificity 92% when <7.10 for >2 hours. Gastric pHi had inferior predictive values.An experimental model of non-occlusive colonic ischaemia was established in the pig. All ischaemic animals had colonic pHi 6.9-7.1 and suffered mucosal ischaemic injury. Controls had no mucosal injury. In a non-randomised study no beneficial effect of dextran was observed. In a randomised study pigs were subjected to ischaemia for 7 hours. In the 12 animals receiving dobutamine, cardiac output was increased by 14% compared to baseline and by 59%o compared to nine controls, but blood flow of the superior mesenteric artery and colonic pHi were unaffected.In conclusion: the.importance of intestinal ischaemia after aortoiliac surgery was verified. Significant risk factors, avoidable by modifications in surgical technique, were identified. High-risk situations were described and the diagnostic value of sigmoidoscopy and of sigmoid pHi monitoring were suggested. An experimental model relevant for testing pharmacological influence was developed and proven reproducible.
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| 3. |
- Wanhainen, Anders, 1966-
(författare)
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Abdominal Aortic Aneurysm : Experience from a Screening Study in Northern Sweden
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Abdominal aortic aneurysm (AAA) is a common problem with life-threatening consequences and was suspected to be a serious health problem in Norsjö, a municipality in northern Sweden. A screening study was undertaken to investigate the prevalence, risk factors associated with AAA and the effect of screening on quality of life (QoL). All men and women, aged 65-75 years, were invited to an ultrasonography (US) examination, 91% attended and 92 subjects were also evaluated with computed tomography (CT).Depending on diagnostic criteria, the AAA prevalence was 3.6-16.9% in men and 0.8-9.4% in women. Seventy-five percent of the differences between US- and CT anteroposterior measurements were less than 5 mm. A decrease in mental health was observed among AAA patients with low baseline SF-36 scale scores. Elevated cholesterol at age 60 years were associated with screening detected AAA after 12 years of follow-up. Smoking, atherosclerosis and having a first degree relative with AAA were associated with AAA at screening. Compared to blood samples obtained 12 years prior to screening an elevation of hsCRP over time was observed among AAA patients. Based on a systematic review of the literature, different screening strategies were analysed in a Markov cohort model. The cost per life year gained ranged from $8 309 to $14 084 and was estimated to $10 474 when 65 year old men were screened once.Conclusions: The highest prevalence of AAA ever reported, in a population-based screening program, was found in Norsjö. The risk of having an AAA at screening showed a strong but complex association with atherosclerosis and its risk factors, genetic and inflammatory mechanisms may also be important. Screening 65-year-old men for AAA may be cost-effective, but QoL aspects on the cost-effectiveness of AAA screening merits further investigation.
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