Biomedical subjects
Publications and source records attributed to C Ohmann.
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In a prospective trial with and without laser therapy the outcome on 105 patients was evaluated according to a defined protocol and terminology. Only patients with actively bleeding lesions during early endoscopy had laser therapy. Patients showing evidence of recent bleeding or no bleeding had none. Defects of the laser equipment or impossibility of reaching a bleeding lesion prevented its use in some patients (control group). There was no difference concerning rate of recurrent bleeding or mortality. Controlled trials with defined groups of patients are urgently needed.
In this paper two problems of computer-aided diagnosis with 'independence Bayes' were investigated: selection of variables and monotonicity in performance as the number of measurements is increased. Using prospective data from patients with upper gastrointestinal bleeding, the stepwise forward selection approach maximizing the apparent diagnostic accuracy was analysed with respect to different kinds of bias in estimation of the true diagnostic accuracy and to the stability of the number and type of variables selected. The results of this study suggest first that the selection of variables should be evaluated against the estimated true diagnostic accuracy obtained using all variables, and secondly that the results of a single selected sequence may be severely biased.
Analysis of the experience with scientific studies on patients with secondary intraabdominal infection has revealed that problems of interpretation and comparability between studies exist as they relate to variable diagnostic criteria, unmeasured severity of disease, and unclear outcome measures. A consistent system of definitions has been developed to address these deficiencies. Intraabdominal infection is defined as clinical peritonitis requiring both operative and microbiological confirmation for proof of infection. The APACHE II system is proposed for grading the severity of the infection and for stratification of patient risk of mortality. Mortality and time until death, on one hand, and recovery and time until recovery, on the other, are proposed as the main outcome measures, both being independently and positively defined. It is anticipated that this system of minimum rules will produce studies that can be compared, hence, accelerating knowledge and understanding about intraabdominal infection and its best treatment.
Acute acalculous cholecystitis (AAC) is a well known complication in severely traumatized patients. Existing data of AAC originate from retrospective analyses and episodic case reports. In a prospective study 45 polytraumatized patients admitted to our intensive care unit from January 1989 to June 1990 were clinically and sonographically screened for this condition at defined time intervals. Trauma scoring was performed according to the injury severity score and polytrauma score. AAC was defined as a combination of hydrops of the gallbladder, an increased wall thickness (> 3.5 mm), and the demonstration of sludge. We were able to document this diagnostic triad in 8 (18%) of 45 patients. As a consequence early elective cholecystectomy was performed in 1 of the 8 patients. The remaining patients were treated conservatively. The incidence of AAC in severely traumatized patients is higher than figures so far published suggest. Ultrasound is a reliable method of early detection and follow-up of this complication.
Acute acalculous cholecystitis is a well known complication in severely traumatized patients. Existing data originate from retrospective analyses and episodic case reports. In a prospective ultrasonographic study 25 polytraumatized patients admitted to our intensive care unit between January 1, 1989, and December 31, 1989, were examined in daily intervals for this condition. Trauma scoring was performed according to the injury severity score (ISS) and polytrauma score (PTS). "Stress cholecystitis" was defined as a combination of hydrops of the gallbladder, an increased mural thickness (> 3.5 mm), and the demonstration of "sludge." We were able to demonstrate this diagnostic triad in four out of 25 patients (= 16%). As a consequence early elective cholecystectomy was done in one patient. The remaining patients were treated conservatively. The incidence of stress cholecystitis in severely traumatized patients is probably higher than figures so far published suggest. Ultrasonography is a reliable method of early detection and follow-up for this complication.
Randomized controlled clinical trials are the preferred scientific method and remain the vital bridge between basic science and improvements in health care according to general agreement. However, discussion has revealed various critical issues in the field of intraabdominal infection. Many of these critical points can be dealt with by prognostic scoring systems. In this paper the application areas for scores in clinical trials on intraabdominal infections are presented. These areas cover: assessment of severity of disease, definition of inclusion/exclusion criteria, analysis of comparability, adjustment for noncomparability, definition of end points and comparison of observed versus predicted outcome. The use of scoring systems in defining treatment policies is still experimental.
Various strategies can be used in the diagnosis of upper gastrointestinal tract bleeding. This study investigates the relevance of anamnestic and clinical findings for the diagnosis of the bleeding source. The authors introduced a computer-aided diagnostic system using Bayes' theorem and compared it with clinicians' predictions using anamnestic and clinical findings only. There was no difference in the overall accuracy rates, but a difference was observed in the diagnostic behaviors of the two "systems." In addition, the discriminatory ability of the computer-aided system, the sharpness of the predictions obtained, and the reliability of the posterior probabilities were analyzed. It is concluded that the clinician and the computer-aided system are not able to discriminate well between the disease categories. Derived classification matrices and probability-based measures show the reasons for the inadequacy of diagnostic information obtainable from the clinical history and physical findings.
Data collection in multi-centre controlled clinical trials is a major problem. We describe a web-based documentation system for data collection via the Internet we have developed in Java. It keeps both the platform independent program (a Java applet) and the database on a single server to which the participating centres have access at any time. It is based on a three-tier model where client requests are handled and monitored by an application server (a Java application). We show the advantages such a system has over the HTML/CGI combination which is often used for database access, as well as possible extensions, e.g. connection to a data dictionary. Finally, we discuss the security problems which arise by the use of the Internet for data collection.
In this review an update concerning the prognostic factors and scoring systems in peritonitis is given. The course of the disease is influenced by the physiological reserve of the patient, the acute severity and the type of the disease, the success of the operation and subsequent management and complications. The Acute Physiology and Chronic Health Evaluation Score (APACHE II) may be used with pre-operative data for the assessment of the severity of the disease or with postoperative data for monitoring. The Mannheim Peritonitis Index (MPI) and the Peritonitis Index Altona are based on pre- and intraoperative data and are also used for severity assessment. Treatment selection with respect to re-operation is supported by the Prognostic Peritonitis Model and the Abdominal Re-operation Predictive Index, covering data from the pre-, intra- and postoperative period. Adequate evaluation data are available for APACHE II and MPI, showing that these instruments are useful for risk assessment, definition of inclusion/exclusion criteria and analysis of comparability in clinical trials. Evaluation of treatment policies and quality assurance can best be performed with APACHE II, monitoring with APACHE II and Multiple Organ Failure scores. Support of individual patient care is still experimental.