6. Krieg:Umbruchvorlage 12.01.2009 9:39 Uhr Seite 34 34 EUROPEAN JOURNAL OF MEDICAL RESEARCH January 28, 2009 Fig. 5. Prognostic impact of the classification according the American Society of Anaesthesiologists (ASA) and course of disease. ASA IV and V patients had to be (A) ventilated for a longer period ( p = 0.003) and (B) required a longer intensive care unit (ICU) stay ( p = 0.009). quired a significantly ( p = 0.009) longer ICU stay (me- dian 20.5; quartile range 25%-75%: 3.25-51; interquar- tile range: 47.75) than patients classified to ASA II and III (median 1; quartile range 25%-75%: 0-9.75; in- terquartile range 9.75) (Fig. 5 B). Seven patients (26.9 %) suffered from acute renal failure, five of which re- quired (19.2 %) hemofiltration or hemodialysis. Fur- ther organ dysfunctions involved in eleven patients (42.3 %) the lung and in six patients (23.1 %) the liver. The overall mortality was 19.2 % (n = 5). All patients who died presented on admission with a severe sys- temic infection with life threatening organ failure and were classified as ASA IV or V patients. ASA IV or V patients had a mortality of 50 %. Survivors had a sig- nificantly lower ASA score on admission ( p = 0.036) than non survivors (Fig. 6). There was no statistical significant correlation between the lengths of symp- toms, comorbidities, white blood cell count, type of infection or areas involved to the mortality or ICU stay. Fig. 6. Relationship between the classification according American Society of Anaesthesiologists (ASA) and mortality While none of the patients classified as ASA II-III died, mor- tality in patients with ASA IV-V was 50 %. ( p = 0.036; Mann-Whitney-test). DISCUSSION Necrotizing fasciitis is a life threatening, rapidly pro- gressing soft tissue infection with a high mortality up to 76 %. However, early diagnosis and extensive surgi- cal debridement of all necrotic tissue has been demon- strated to improve survival [7, 8, 19, 20]. Paucity of clinical findings in the early course of the infection makes a timely diagnosis difficult. Early signs of dis- ease do not include skin necrosis, crepitus or dishwa- ter pus, in particular in type II infections. The therapy has to be initiated as early as possible, but radical skin debridement in patients who turn out not to suffer from necrotizing fasciitis has to be avoid- ed. Therefore further diagnostic tools such as imaging procedures or histopathologic examination have to be used. Yen and colleagues [21] applied the criterion of diffuse thickening of the subcutaneous tissue accom- panied by a fluid layer amounting more than four mil- limetres along the fascia in a prospective study using ultrasound techniques. They found a sensitivity of 88.2 % and a specificity of 95.4 %. More frequently used, CT scan may recognize fasciitis by detecting dif- fuse enhancement and thickening of the superficial and deep fascia as well as soft tissue gas or fluid col- lections [14, 15]. Consistent with previous reports typ- ical diagnostic features at CT in our group were fascial thickening with enhancement and edema of the adja- cent muscle, as well as fat stranding, fluid collections and gas tracking along fascial planes. CT scanning might help the surgeon to show the extension of an infectious process, but was in our group limited in its validity to distinguish between necrotizing fasciitis and other soft tissue infections. More suitable in distin- guishing between necrotizing fasciitis and cellulites seems to be MR imaging with a reported sensitivity of