PubMed Health⌕ Search

Biomedical subjects

B R Osswald

Publications and source records attributed to B R Osswald.

At least 19 recordsLinked to original sources
PubMed2002

Minimal early mortality in CABG--simply a question of surgical quality?

BACKGROUND: The increasing number of risk scores and models for the evaluation of the early risk after cardiac surgery reflects the interest in 'calculating' the risk of adverse events. Different time intervals, but also different 'types' of death are generally accepted in the evaluation of early mortality. The aim of this study was to focus on the differences in the calculation of early mortality and to focus on their potentially misleading impact on risk stratification. METHODS: We investigated 7,436 patients who underwent coronary artery bypass grafting from June 30, 1988 through June 30, 2001. A follow-up was performed 180 days after operation (98.7 % complete). RESULTS: According to the definition of 30-day mortality to represent the total time interval between an intervention and the 30th postoperative day, the 30-day mortality was 5.92 % (n = 440 patients). Hospital mortality reflects the number of deaths from the day of intervention through the patient's individual discharge, independent of any fixed time interval. Hospital mortality was 5.86 % (n = 436 patients) in our patient group. 30-day hospital mortality requires the investigation of hospital mortality until the 30th postoperative day; in-hospital and general mortality after the 30th postoperative day remained excluded from the analysis; 30-day hospital mortality was 5.19 % (n = 386 patients). Assuming a maximum hospital stay of 5 days, hospital mortality would decrease to 2.64 % (n = 196 patients). CONCLUSIONS: 30-day mortality, hospital mortality and 30-day hospital mortality are used to determine early outcome. The present data indicate the vulnerability of non-standardized time intervals to discharge policy. However, both hospital mortality and 30-day hospital mortality are predominantly used in current risk scores and models. In view of the comparability and meaning of data, the methodology for the evaluation of early risk should be reconsidered.

Coronary Artery Bypass↗
PubMed2002

[Stability of the Euro-score as an identification tool for patient risk groups -- dependency of the applied documentation system].

From the different methods for risk adjustment, scores allow a rough classification of the patients. The Euroscore represents one of the most modern scores. The most recent version of the documentation system of the German Society for Thoracic and Cardiovascular Surgery may be used without extended extra-work to evaluate the Euroscore despite the presence of various limitations. The investigation of the scores with nearly complete adaptation of the variables of the quality assurance documentation to the original definition showed no substantial differences between the score groups. However, many methodological implications favor the development of self-evaluated models to obtain a most recent weight for each risk factor and to be able to take into account new therapeutical options. These models can be evaluated by the existing database and extended by the most recent data.

Cardiac Surgical Procedures↗
PubMed2001

Does the completeness of revascularization affect early survival after coronary artery bypass grafting in elderly patients?

OBJECTIVE: Usefulness and risks of incomplete versus complete revascularization are still matters of ongoing discussions. Because an increasing number of elderly patients are undergoing coronary artery bypass grafting (CABG), the question arises whether a less extensive surgical approach is more prudent than complete revascularization. METHODS: Of 6531 patients undergoing isolated CABG, 859 were 75 and older at the time of operation. Mean age of the 859 patients was 77+/-2.7 years (median: 76 years); 65% were men. Follow-up enquiry by questionnaire was performed at the 180th postoperative day with a completeness of 95.6%. Assessment of the impact of incomplete revascularization utilized both multivariable analysis and propensity score matching to account for selection factors. RESULTS: Incomplete revascularization was performed in 133 patients (16%). The most common reasons for incomplete revascularization were small vessels (55%) and massive calcification (32%). Mortality until 180 days after CABG was higher (n=32; 24%) after incomplete than after complete revascularization (n=105; 15%; P=0.005). By logistic multivariable regression, incomplete revascularization was identified as an independent risk factor for death (Odds ratio, 1.8; P=0.015). By time-related analysis, incomplete revascularization predominantly affected the early period after CABG (P=0.001). Aortic cross clamping time was only slightly shorter for the group with incomplete (59+/-27 min (median: 55 min) vs. 63+/-26 min (median: 58 min); P=0.1). CONCLUSIONS: Incomplete revascularization increases the early risk of death after CABG in patients aged 75 years and older. The potential compensating benefit of the shorter aortic cross clamping time does not outweigh the advantages of complete revascularization. Thus, in the era of high-volume interventional approaches and minimally invasive techniques, the advantages of complete revascularization need to be considered.

Aged↗
PubMed2001

Far-field R wave oversensing in a dual chamber arrhythmia management device: predisposing factors and practical implications.

Initial experience with the Medtronic Jewel 7250, the ICD designed to detect and treat ventricular and supraventricular tachyarrhythmias, is very promising. Its effectiveness, however, depends on sensing performance, which has not yet been systematically examined. The aim of the study was to determine the incidence of, predisposing factors for, and practical implications of far-field R wave oversensing (FFRWOS) in this dual chamber ICD. During a total follow-up of 797 months in 48 patients who had the Jewel 7250, follow-up strip charts, 12-channel Holter recordings and, in particular cases, Holter recordings with intracardiac markers were analyzed for the presence of FFRWOS. FFRWOS was documented in ten (21.3%) patients. Compared to other lead locations, the right atrial appendage lead position was most frequently associated with FFRWOS (7/27 vs 3/21, P < 0.05). Patients with FFRWOS had significantly more treated and nontreated atrial episodes, many of which were judged to have been detected inappropriately. In one case, inappropriate atrial antitachycardia pacing due to R wave oversensing triggered sustained ventricular tachycardia, terminated eventually with a high energy shock. In dual chamber ICDs, FFRWOS may represent a frequent phenomenon possibly leading to serious consequences. For atrial leads, a lateral atrial wall position seems to be preferable. In most cases, FFRWOS can be eliminated by optimization of atrial sensing parameters. Given the possibility of ventricular proarrhythmia with atrial pacing therapy, the capability of ventricular backup defibrillation in respective devices is at least reassuring.

Adult↗
PubMed2001

Does the completeness of revascularization contribute to an improved early survival in patients up to 70 years of age?

OBJECTIVE: In the era of a renewal of incomplete revascularization approaches, the controversy reappears as to whether the approach for complete revascularization is of prognostic value. The clear advantage of complete revascularization in elderly patients has recently been published. However, for the younger patient group, there is no conclusive information available so far. The aim of our study was to investigate the effect of complete vs. incomplete revascularization in patients up to 70 years of age. PATIENTS AND METHODS: 6531 patients underwent isolated CABG. 5003 of these patients were aged up to 70 years at the time of operation. RESULTS: Incomplete revascularization was performed in 534 (10.7 %) patients. The most common reasons for incomplete revascularization were small vessels and massive calcification. The differences in mortality up to the 180(th) day after CABG are statistically significant. By Kaplan-Meier analysis, the time relationship between incomplete revascularization and death affects predominantly the very early period after CABG. By logistical regression, incomplete revascularization was found to be an independent risk factor for death after CABG. CONCLUSION: Incomplete revascularization affects the early outcome after CABG in patients up to 70 years of age as an independent risk factor for death. In view of recent approaches for primarily incomplete CABG, our results indicate the necessity to reconsider the advantages of complete revascularization.

Age Factors↗
PubMed2000

Target, application, and interpretation of scores and alternative methods for risk assessment in cardiac surgery.

BACKGROUND: The more popular the use of different methods for risk adjustment becomes, the more often data are applied without any regard about the primary target and/or about important assumptions. Furthermore, risk adjustment is no longer restricted for quality assurance purposes, but became a "tool" of health policy. Few working groups currently use risk adjustment for the development of new therapeutic concepts. The aim of our study is to clarify possibilities and limitations of popular risk adjustment methods. PATIENTS AND METHODS: 4985 Patients underwent isolated CABG. Statistics was performed by calculating descriptive statistics, Parsonnet, and Higginsscores. Furthermore, the parametric, time-adjusted hazard function by Blackstone was used. RESULTS: Descriptive statistics allows intra-, and interinstitutional comparisons of single items to identify "outlying" results. Risk scores aim to predict preoperatively the risk category of the patient who undergoes cardiac surgery. However, since different scores are based on a score-specific combination of variables, and different definitions of the investigation interval, different results may occur, when different scores are calculated for a single patient. However, the use for example, of scores in patient groups allows description of changing risk structures. Most of the scores derive from univariate analyses and monophasic functions. However, survival curves are predominantly multiphasic and require a consideration of the time-dependency of "risk factors". DISCUSSION: An increasing number of patients with severe comorbidity undergoes cardiac surgery. To evaluate reliably present and futurous therapeutic options, risk adjustment is necessary. Since various tools for risk-adjustment are available, a serious discussion about reliability and application is necessary.

Aged↗
PubMed1999

The meaning of early mortality after CABG.

OBJECTIVE: Investigations of early mortality after coronary artery bypass grafting (CABG) are predominantly based on 30-day mortality or hospital mortality. The advantages, disadvantages, and usefulness of hospital mortality and 30-day mortality analyses to investigate the early risk after CABG are evaluated. METHODS: A total of 4985 patients underwent isolated CABG from June 1988 to June 1997. A follow-up was performed 180 days after CABG (response rate: 98.6%). RESULTS: The mean hospital stay was 13.5+/-9.6 days, the range was 0 to 142 days (25% quartile, 9 days; median, 12 days; 75% quartile, 15 days). The hospital mortality was 5.3%. The 30-day mortality was 5.6%. The non-parametric Kaplan-Meier curve of the time interval 0-180 days postoperatively proves the persistence of the still decreasing behaviour of the survival curve beyond the 30th day until about the 60th postoperative day. Stratified by era of operation, the 'early phase' after CABG seems to be prolonged beyond 30 days at least for the more recent operation era since 1991. Risk stratification proves that the higher the risk group, the more the early phase tends towards a prolongation. CONCLUSIONS: The hospital mortality reflects institutional habits concerning postoperative patient care. Therefore, a systematic underestimation of early mortality is likely. In contrast to hospital stay, the evaluation of 30-day mortality requires a follow-up procedure but allows interinstitutional comparisons. Nevertheless, 30-day mortality systematically underestimates the early risk, at least in the more recent CABG period. So, a standardized evaluation of a longer time period (p.e. 180 days) is recommended.

Coronary Artery Bypass↗
PubMed1999

Influence of follow-up response on risk-factor analysis.

BACKGROUND: Long-term analyses after coronary artery bypass grafting (CABG) are used to investigate therapeutical options and factors influencing the natural course of ischemic heart disease. In general, long-term studies require a follow-up. Dependent on the interval between the intervention and the follow-up procedure a certain amount of patients is lost to follow-up. The aim of the present study was to examine the influence of incomplete follow-up on conclusions regarding the postoperative patient outcome. For the investigation, the same statistical methods were applied to the data accumulated by the 70% and by the 90% responses. METHODS: 2012 patients underwent isolated CABG between June 1988 and December 1992. For data acquisition, tools of the HVMD (Heidelberger Verein für multizentrische Datenanalyse e.V.) were used. Analyses were performed using tools of SAS (Statistical Analysis Systems, Inc.). The parametric, time-adjusted hazard function method was employed. A first follow-up questionnaire, was distributed six months after operation with a 97.8% response. In February 1997 the same questionnaire was sent to patients and their general practioners. The primary response to that was 68.9% (approximately 70%). Then another mailing of the same questionnaire and phone calls to patients and their home doctors raised the response to 93.7% (approximately 90%). RESULTS: The mean follow-up was 1378 days in the group with 70% response and 1682 days in the group with 90% response. The parametric, time-adjusted hazard function showed a very similar pattern of factors in the early phase of both groups. In the 90% response group, the intermediate phase reached a higher relative influence than in the 70% response group. The relative influence of the late phase showed an inverse pattern. In the multivariate analysis most of the variables which had been identified by the 70% response model reappeared in the 90% response model. However, there were some potentially important and interesting differences. CONCLUSIONS: The results indicate the necessity to carefully consider the acceptance of incomplete follow-up for differentiated risk adjustment.

Coronary Artery Bypass↗
PubMed1997

Severe abdominal pain and thrombocytopenia--typical symptoms of occult jejunal diverticulum perforation?

Complicated small-bowel diverticula cause abdominal pain, gastrointestinal hemorrhage, small-bowel obstruction, and peritonitis. The present patient, had an occult perforation of a small-bowel diverticulum. There were diverticula throughout the whole small bowel. Preoperatively thrombocytopenia (98,000 thrombocytes/cc), was noted. Without any special treatment, i.e., transfusion, the thrombocyte level increased after surgical treatment to normal levels. Although the incidence of small-bowel diverticula appears to be low (0.1%-2.3%) complications may become life-threatening. The level of thrombocytopenia may reflect the extent of inflammation.

Abdominal Pain↗
PubMed1997

Successful revascularisation for unstable angina of a patient with asymptomatic bilateral internal carotid occlusion, 70% stenoses of the external carotid arteries, and other circulation disturbances.

Nowadays, advanced surgical and anaesthesiological techniques of coronary artery bypass grafting minimize the risk of severe complications in patients with advanced arteriosclerotic cerebrovascular disease. Nevertheless, in case of highly compromised cerebrovascular status, the decision whether to undertake coronary artery bypass grafting or not requires special patient-related consideration. A severe, unstable angina made it necessary to perform coronary bypass grafting in a patient with bilateral internal carotid occlusion, a bilateral mid-stage stenosis of both external carotid arteries, a diminished flow within the right vertebral artery, and a subsequently impaired intracranial blood flow. Intraoperatively, besides the usual hemodynamic measurements, laser-Doppler flow probes were placed on the left and right upper temple to monitor relative changes of the cerebral blood supply. Using an individual perioperative management, the patient experienced a normal postoperative course and was discharged in good condition.

Aged↗
PubMed1997

[Internal quality assurance or Hawthorne effect?].

The tendency of study participation per se to affect outcome is described by the term Hawthorne effect. This process defines the first step for internal quality assurance. However, whenever an attempt is made to describe the effects of quality assurance in more detail specific mathematical tools are required, including a database system that allows the calculation of clinical profiles, problem profiles, time-related variance of variables, univariate and multivariate statistics, calculation of scores and application of the hazard function. However, it has to be considered that any mathematical model is a way to present a hypothesis and not a proof. Whenever a proof is required, one should not ask for internal quality assurance, but design a randomized study.

Cardiac Surgical Procedures↗
PubMed1996

Continuous measurement of porcine renal cortex microcirculation with enhanced thermal diffusion technology.

Continuous monitoring of renal cortical blood flow (RCBF) in the perioperative setting of aortic or renal vascular surgery could facilitate the early detection of vascular complications, possibly resulting in a reduction of postoperative renal failure. A new prototype system for measurement of parenchymous organ perfusion based on the principle of thermal diffusion ("TD"-Thermal Diffusion Electrode, Thermal Technologies Inc., Cambridge, MA, USA) was used for RCBF measurements in the outer cortex of the porcine kidney. We validated the sensitivity of the device to detect renal blood flow impairment, comparing TD flow data with renal artery blood flow values (RABF), measured by ultrasonic flow probes. The hypothesis was tested that acute disturbances of RCBF, induced by a variable degree of renal artery stenosis, can be immediately detected and continuously monitored by TD measurements in the porcine renal cortex. Mean baseline RCBF measured by TD electrodes was 68.1 +/- 25.0 ml/100 g/min. Mean baseline RABF was 102.1 +/- 26.6 ml/min. Controlled induction of a variable degree of renal arterial occlusion by implanted vascular balloon occluders was always followed by an immediate and proportional decline of RCBF, as measured by TD. Flow data obtained with both methods were significantly correlated by linear regression (r=.82, r2=.68; P < 0.0001). Dynamic changes of RABF in the time course of renal artery partial/total occlusion and arterial flow release could be continuously followed by detection of corresponding flow changes of RCBF. We conclude that the TD system investigated in the current study allows a continuous and sensitive determination of porcine renal cortex perfusion. A clinical evaluation of the method, e.g., in the perioperative setting of aortic or renal transplantation surgery, now appears to be justified.

Animals↗
PubMed1996

[Splenic cyst--a classical "incidental finding"].

Splenic cysts cannot be summarized in one entity but open a wide field of aetiopathogenetic factors. The most common types of splenic cysts in central Europe are of epithelial or traumatic origin. Since ultrasound is widely used, the incidence of splenic cysts increased to about 1%. Rarely, splenic cysts give specific symptoms. Giant cysts cause unspecific abdominal pain, sometimes even organ displacement, possibly leading to a decreased function of related organs. In case of rupture, splenic cysts may become life-threatening. We present a patient suffering a giant splenic cyst and give an overview of diagnostic and therapeutic aspects of splenic cysts.

Adolescent↗
PubMed1996

[Quality assurance in heart surgery: 8 years experience with a "feedback-control" system in Heidelberg].

An important aspect of quality assurance in cardiac surgery covers the epidemiological analysis of patient data. After an 8 year period of clinical experience with quality assurance, we summarize and evaluate current concepts and actual experiences regarding a special type of database application and organisation ("feedback-control-system") for quality assurance. It had been developed to meet and solve the problems related to the data acquisition process, that are typically present in the clinical routine of quality assurance. In 1988 the "feedback-control-system" was designed and implemented in the Department of Cardiac Surgery at Heidelberg University. Since then it had been continuously improved and adapted to satisfy current needs in cardiac surgery. More than 1500 items are now recorded routinely per patient. At present, detailed information of more than 10,000 patients is available for the specific methods of analysis in the field of quality assurance. The basic concept included 1. the integration of the data acquisition in the daily clinical routine, 2. the evaluation and improvement of collected data material by means of "output-functions", that require previously recorded reliable data (that is automatically computer generated operation reports, letters, statistics, accounting etc.), and 3. to ensure that the medical and non-medical staff members participate in the advantages and the responsibilities of the data-base system for quality assurance. Analyses of perioperative risks and results, early discovery of trends, identification of special subpopulations receiving special types of treatment in cardiac surgery etc. have now become a regularly performed tool in clinical routine. This includes the availability of "problem profiles", "trend analysis", the use of simple concluding statistics as well as the calculation of multivariable models. This internal quality assurance is completed by "multicentric" comparisons with further hospitals already using the same data-base system (external quality assurance). Within 8 years, the feedback-control-system has become a reliable and valuable tool for quality assurance in daily routine. The high acceptance of the database system is related to the advantages it provides for every participant. We conclude that the concept of data evaluation and improvement by means of "output functions" and "integration of data acquisition in clinical routines" has proved to be efficient in everyday practice. The sensitivity and specifity to such a feedback controlled system as a tool for measuring surgical quality, however, still remains a matter requiring further research.

Cardiac Surgical Procedures↗
PubMed1995

[Induction of impaired hepatic microcirculation by in situ hilus preparation in liver explantation].

AIM: Usually, in-situ preparation of the hepatic hilar structures is performed prior to the perfusion with preservation solution. Aim of this study was to investigate mechanical effects of liver preparation on the hepatic microcirculation. METHODS: 16 pigs (German landrace) were randomized in two groups. In both groups, laparotomy was performed after intratracheal intubation. Subsequently, a thermal diffusion probe was implanted into the medial left liver lobe for quantification of microperfusion. In group A (n = 8), bile duct, hepatic artery, and portal vein were exposed and the lesser omentum transsected thereafter. Ultrasound-volume-probes were placed around the hepatic artery and portal vein. Simultaneous measurement of hepatic microperfusion and total liver blood flow was performed five minutes after the end of liver preparation. In group B (n = 8) hepatic microperfusion was quantified 45 minutes after laparotomy without further manipulations. RESULTS: By the preparation, liver perfusion was significantly reduced in group A from 78 +/- 13 ml/100g/min to 61 +/- 16 ml/100g/min. After preparation a total liver blood flow of 137 +/- 46 ml/100g/min was recorded indicating a shunt fraction of 51 +/- 21%. In contrast, hepatic microperfusion in group B remained at baseline during the whole observation period (79 +/- 3 ml/100g/min vs. 78 +/- 5 ml/100g/min). CONCLUSION: In-situ liver preparation induces a relevant disturbance of hepatic microcirculation. Preservation perfusion shortly after surgical manipulation could become ineffective because of an increase in shunt flow. If the regeneration period is too short, e.g. lack of heart explantation, the quality of the liver graft could be limited.

Animals↗