Michael Imhoff

• MD, PhD
• Professor at Ruhr University Bochum

Monitoring critically ill patients by means of modern computer and measurement technologies generates great amounts of data. The real time statistical analysis of these data provides important insights into patients’ state of health and the necessary medical measures needed to save lives and avoid false alarms.

Bei der Überwachung kritisch kranker Patienten mittels moderner Computer- und Messtechnologien fallen immense Datenmengen an. Die intelligente statistische Analyse dieser Daten in Echtzeit liefert wichtige Informationen über den Gesundheitszustand und notwendige medizinische Maßnahmen, um Leben zu retten und falsche Alarme zu vermeiden.

It is crucial to precisely monitor ventilation and correctly diagnose ventilation-related pathological states for averting lung collapse and lung failure in Intensive Care Unit (ICU) patients. Although Electrical Impedance Tomography (EIT) may deliver this information continuously and non-invasively at bedside, to date there are no studies that sys...

Die Begriffe E‑Health und Digitalisierung sind Kernelemente eines Wandels unserer Zeit. Wesentliche Treiber dieses Wandels sind – neben einem dynamischen Markt – die gravierenden Vorteile für das Gesundheitswesen in der Bearbeitung von Aufgaben und Anforderungen. Das Aufkommen großer Datenmengen, das rapide wachsende medizinische Wissen, die rasch...

Complex, often high-dimensional time series are observed in medical applications such as intensive care. We review statistical tools for intelligent alarm systems, which are helpful for guiding medical decision-making in time critical situations. The procedures described can also be applied for decision support or in closed-loop controllers. Robust...

No abstract is available for this article.

Metrology is the science of measurements. Although of critical importance in medicine and especially in critical care, frequent confusion in terms and definitions impact either interphysician communications or understanding of manufacturers' and engineers' instructions and limitations when using devices. In this review, we first list the terms defi...

In day to day medical care, patients, nursing staff and doctors currently face a bewildering and rapidly growing number of health-related apps running on various "smart" devices and there are also uncountable possibilities for the use of such technology. Concerning regulation, a risk-based approach is applied for development and use (including safe...

The measurement of body (core) temperature is well established in clinical care. However, there are still numerous challenges especially in mature and premature infants including the lack of a reliable, non-invasive and fast measurement method for body core temperature. The current standard of care, technological challenges and limitations , as wel...

Pre-term babies are not able to efficiently maintain normothermia due to limited capacities of their regulation system dealing with changing environmental conditions. Typically immature neonates are very often hypotherm being associated with negative impact on survival rate. Thermal management of neonates can be difficult across the continuum of ca...

[english] IEC 80001-1 is an international standard and offers recommendations for a risk management process for medical information technology networks (MITs). MITs are defined as IT networks incorporating at least one medical device. The goal is to build and maintain reliable and secure MITs for hospitals of all kids. To achieve it, the standard s...

For data streams which are distorted by noise and outliers, it is a basic goal to extract the unknown underlying signal carrying the relevant information in real time. We review procedures for real time signal extraction or filtering, which are based on robust location and regression estimators applied to moving time windows. Since Repeated Median...

Accidental hypothermia and its variant, perioperative hypothermia, is a rather common clinical phenomenon in patients. This is surprising because the negative effects on clinical outcomes are well described and effective patient-warming devices are available today. The aim of this paper is to describe the physiologic background cf accidental and pe...

As a result of the increasing pressure on health care expenditures calculations of the return on investment (ROI) have been attempted in assessing the utility of medical equipment purchases. The measurement of ROI requires an in-depth analysis of equipment cost, cost structure, and medical processes. ROI analysis in health care is more complicated...

For many decades the measurement of body core temperature has been ubiquitously established in medical and non-medical applications, e.g., in hospitals, occupational medicine, sports medicine, military and other settings. However, there are still numerous challenges, such as the precise definition of the body core temperature, establishing the clin...

The high number of false positive alarms has long been known to be a serious problem in critical care medicine - yet it remains unresolved. At the same time, threats to patient safety due to missing or suppressed alarms are being reported. The purpose of this paper is to present results from a workshop titled "Too many alarms? Too few alarms?" orga...

Online-monitoring systems in intensive care are affected by a high rate of false threshold alarms. These are caused by irrelevant noise and outliers in the measured time series data. The high false alarm rates can be lowered by separating relevant signals from noise and outliers online, in such a way that signal estimations, instead of raw measurem...

As a result of the increasing pressure on health-care expenditures calculations of the return on investment (ROI) have been attempted in assessing the utility of medical equipment purchases. The measurement of ROI requires an in-depth analysis of equipment cost, cost structure, and medical processes. ROI analysis in healthcare is more complicated a...

The alarms of medical devices are a matter of concern in critical and perioperative care. The high rate of false alarms is not only a nuisance for patients and caregivers, but can also compromise patient safety and effectiveness of care. The development of alarm systems has lagged behind the technological advances of medical devices over the last 2...

To validate cardiovascular alarms in critically ill patients in an experimental setting by generating a database of physiologic data and clinical alarm annotations, and report the current rate of alarms and their clinical validity. Currently, monitoring of physiologic parameters in critically ill patients is performed by alarm systems with high sen...

Clinical information systems can record numerous variables describing the patient's state at high sampling frequencies. Intelligent alarm systems and suitable bedside decision support are needed to cope with this flood of information. A basic task here is the fast and correct detection of important patterns of change such as level shifts and trends...

Cardiovascular monitoring alarms are frequent in intensive care units (ICUs) and lead to noise levels often exceeding 80 dB. The aim of this study was to evaluate if there are relevant differences between ICUs with different subspecialties in the frequency and distribution of alarm signals, their occurrence during the day, the types of alarms and t...

Alarms in medical devices are a matter of concern in critical and perioperative care. The high rate of false alarms is not only a nuisance for patients and caregivers, but can also compromise patient safety and effectiveness of care. The development of alarm systems has lagged behind the technological advances of medical devices over the last 20 ye...

Introduction Cardiovascular monitoring alarms are frequent in intensive care units (ICUs) and lead to noise levels often exceeding 80 dB. The aim of this study was to evaluate if there are relevant differences between ICUs with different subspecialties in the frequency and distribution of alarm signals, their occurrence during the day, the types of...

Monitoring of physiologic parameters in critically ill patients is associated with an enormous number of alarms, leading to reduced clinical value with high sensitivity but low specificity. To evaluate opinions of intensive care unit (ICU) staff on current monitoring we conducted a survey of German ICUs. Furthermore, the survey aimed to assess requ...

Monitoring of physiologic parameters in critically ill patients is currently performed by threshold alarm systems with high sensitivity but low specificity. As a consequence, a multitude of alarms are generated, leading to an impaired clinical value of these alarms due to reduced alertness of the intensive care unit (ICU) staff. To evaluate a new a...

Accurate, non-invasive diagnosis of, and screening for, coronary artery disease (CAD) and restenosis after coronary revascularization has been a challenge due to either low sensitivity/specificity or relevant morbidity associated with current diagnostic modalities. To assess sensitivity and specificity of a new computerized, multiphase, resting ele...

We propose a new regression-based filter for multivariate time series that separates signals from noise and outliers in real time. The new method merges the advantageous properties of two existent filtering procedures for online-monitoring time series. Our multivariate and robust procedure yields signal estimations at the right end point of a movin...

To assess the sensitivity and specificity of a new computer-enhanced resting electrocardiographic analysis device for the detection of coronary stenosis, 189 patients (aged 61.3+/-12.9 years, 57 women) scheduled for coronary angiography from 4 Asian centers were included in an observational study. Angiographic results were independently classified...

We propose a new regression-based filter for multivariate time series that separates signals from noise and outliers in real time. The new method merges the advantageous properties of two existent filtering procedures for online-monitoring time series. Our multivariate and robust procedure yields signal estimations at the right end point of a movin...

Resting electrocardiogram (ECG) shows limited sensitivity and specificity for the detection of coronary artery disease (CAD), where patients with a history of coronary revascularization may pose special challenges. Several methods exist to enhance sensitivity and specificity of resting ECG for diagnosis of CAD, but such methods are not better than...

PURPOSE: To evaluate a new computerized ECG system for the detection of myocardial ischemia due to hemodynamically relevant coronary re-stenosis, de novo stenosis, or graft stenosis after revascularization. METHODS: 213 patients (68 female, mean age 63.9 +/- 9.8) were included who were scheduled for follow-up angiography after coronary revasculariz...

Tight glucose control (TGC) is becoming increasingly accepted in intensive care. One essential component of this concept is monitoring of blood glucose levels. Ideally, this should be done automatically, in a timely fashion, at sufficiently close intervals, and with adequate precision. Numerous industry and academic groups are working in this area....

Resting electrocardiogram (ECG) shows limited sensitivity and specificity for the detection of coronary artery disease (CAD). Several methods exist to enhance sensitivity and specificity of resting ECG for diagnosis of CAD, but such methods are not better than a specialist's judgement. We compared a new computer-enhanced, resting ECG analysis devic...

Immobility is associated with complications involving many body systems. To review the effect of rotational therapy (use of therapeutic surfaces that turn on their longitudinal axes) on prevention and/or treatment of respiratory complications in critically ill patients. Published articles evaluating prophylaxis and/or treatment were reviewed. Prosp...

The alarms of medical devices are a matter of concern in critical and perioperative care. The frequent false alarms not only are a nuisance for patients and caregivers but can also compromise patient safety and effectiveness of care. The development of alarm systems has lagged behind the technological advances of medical devices over the last 20 ye...

Im Rahmen des Projektes ”Zeitreihenanalytische Methoden zur Behandlung von Online-Monitoring-Daten aus der Intensivmedizin“ im Sonderforschungsbereich 475 wird eine klinische Studie zur Evaluierung und zum Vergleich von Alarm-Algorithmen für die Patientenüberwachung auf Intensivstationen durchgeführt. Die Studie erhebt klinisch annotierte Daten. Di...

Clinical Information Systems facilitate the electronic capture of almost all patient related data at the point of care. In theory, these data can then be easily analyzed as it is available in electronic format. This article discusses the processes and prerequisites needed for successful and clinically useful analysis of CIS data. Examples are given...

On two intensive care units (ICUs), one in the UK, the other in Germany, the efforts and expenses necessary to implement and maintain a CIS were evaluated. A major expense of man power and money has to be invested to install and maintain a fully fledged CIS. The overall time from the first planning of the conceptual framework to the "go live" date...

Introduction An abundance of information is generated during the process of critical care. Much of this information can now be captured and stored using clinical information systems (CIS) that have become commercially available for use in intensive care over the last years. These systems provide for a complete medical documentation at the bedside a...

Health care information systems have the potential to enable better care of patients in much the same manner as the widespread use of the automobile and telephone did in the early 20th century. The car and phone were rapidly accepted and embraced throughout the world when these breakthroughs occurred. However, the automation of health care with use...

The online detection of a monotonic trend in a time series with a time-varying mean is an important task in medical applications like intensive care monitoring, that is rendered difficult by autocorrelations. Statistical control charts designed for industrial processes are not adequate as they typically rely on a fixed target value, and many detect...

Healthcare, in general, and intensive care, in particular, today face two overwhelming challenges in all developed countries: improving quality of care and, at the same time, improving cost-effectiveness of care. These challenges can only be mastered by analysing, measuring and controlling the core processes of care. Advanced medical information te...

We present a robust graphical procedure for routine detection of isolated and patchy outliers in univariate time series. This procedure is suitable for retrospective as well as for online identification of outliers. It is based on a phase space reconstruction of the time series which allows to regard the time series as a multivariate sample with id...

In intensive care, physiological variables of the critically ill are measured and recorded in short time intervals. The proper extraction and interpretation of the essential information contained in this flood of data can hardly be done by experience alone. Typically, decision making in intensive care is based on only a few selected variables. Alte...

We discuss methods for robust signal extraction from noisy physiological time series as measured in intensive care. The aim is a method which allows a fast and reliable de-noising of the data and separation of artifacts from relevant changes in the patients condition. For approximating local linear trends we use robust regression estimators. We exa...

Nowadays physicians are confronted with high-dimensional data generated by clinical information systems. The proper extraction and interpretation of the information contained in such massive data sets, which are often observed with high sampling frequencies, can hardly be done by experience only. This yields new perspectives of data recording and a...

Principal component analysis (PCA) is frequently used for detection of common structures in multivariate data, e.g. in statistical process control. Critical issues are the choice of the number of principal components and their interpretation. These tasks become even more difficult when dynamic PCA (Brillinger, 1981) CitationRef CitationID Omitted t...

In intensive care, clinical information systems permanently record more than one hundred time dependent variables. Besides the aim of recognising patterns like outliers, level changes and trends in such high-dimensional time series, it is important to reduce their dimension and to understand the possibly time-varying dependencies between the variab...

The detection of patterns in monitoring data of vital signs is of great importance for adequate bedside decision support in critical care. Currently used alarm systems, which are based on fixed thresholds and independency assumptions, are not satisfactory in clinical practice. Time series techniques such as AR-models consider autocorrelations withi...

In intensive care physiological variables of the critically ill are measured and recorded in short time intervals. The proper extraction and interpretation of the information contained in this flood of information can hardly be done by experience alone. Intelligent alarm systems are needed to provide suitable bedside decision support. So far there...

We discuss methods for dimension reduction like the selection of variables and the calculation of principal components in the clinical context of online monitoring in intensive care. Principal component analysis may be advantageous since principal components linearly combine the information in the observed variables in a way that is optimal in a ce...

Health informatics is the development and assessment of methods and systems for the acquisition, processing and interpretation of patient data with the help of knowledge from scientific research.

All Western countries are struggling to curb the continuing growth of health care expenditures. Dramatic changes are happening to the health care systems all over the world. There are many reasons for this development. While an in-depth discussion of these problems is beyond the scope of this presentation, it is worth mentioning that areas of advan...

In modern statistical process control, intelligent alarm systems have to be constructed which extract the important information from multivariate time series and detect critical "out-of control" states of the underlying mechanism quickly and reliably. Regarding high-dimensional time series, statistical methods for dimension reduction can help to co...

In intensive care physiological variables of the critical-ly ill are measured and recorded in short time intervals. The existing alarm systems based on fixed thresholds produce a large number of false alarms. Usually the change of a variable over time is more informative than one pathological value at a particular time point. Intelligent alarm syst...

Health informatics is the development and assessment of methods and systems for the acquisition, processing and interpretation of patient data with the help of knowledge from scientific research. This definition implies that health informatics is not tied to the application of computers but more generally to the entire management of information in...

For the implementation of time-critical decision support algorithms a precise relation between intervention and effect needs to be established. We evaluated for catecholamines and infusions the relation in time between charted dose and effect on hemodynamic variables. The onset of the change of the hemodynamic variables was determined by autoregres...

Traditional expert systems rely on a tedious, labor-intensive and time-consuming approach in their development while they do not effectively exploit existing medical databases. We applied a new concept of combining time series analysis and a knowledge base system with learning and revision capabilities (MOBAL) for rapid development of decision supp...

Clinical information systems can record numerous variables describing the patient’s state at high sampling frequencies. Intelligent alarm systems and suitable bedsidedecision support are needed to cope with this flood of information. A basic task here is the fast and correct detection of important patterns of change such as level shifts and trends...

Intelligent alarm systems are needed for adequate bedside decision support in critical care. Clinical information systems acquire physiological variables online in short time intervals. To identify complications as well as therapeutic effects procedures for rapid classiffication of the current state of the patient have to be developed. Detection of...

Operational protocols are a valuable means for quality control. However, developing operational protocols is a highly complex and costly task. We present an integrated approach involving both intelligent data analysis and knowledge acquisition from experts that supports the development of operational protocols. The aim is to ensure high quality sta...

Intelligent alarm systems are needed for adequate bedside decision support in critical care. Clinical information systems acquire physiological variables online in short time intervals. To identify complications as well as therapeutic effects procedures for rapid classification of the current state of the patient have to be developed. Detection of...

To evaluate the reliability of whole-body impedance cardiography with two electrodes on either both wrists or one wrist and one ankle for the measurement of cardiac output compared with the thermodilution method. Prospective, clinical investigation Surgical intensive care unit of a university-affiliated community hospital. Simultaneous cardiac outp...

Operational protocols are a valuable means for quality control. However, developing operational protocols is a highly complex and costly task. We present an integrated approach involving both intelligent data analysis and knowledge acquisition from experts that support the development of operational protocols. The aim is to ensure high quality stan...

In modern intensive care physiological variables of the critically ill can be reported online by clinical information systems. Intelligent alarm systems are needed for a suitable bedside decision support. The existing alarm systems based on fixed treshholds produce a great number of false alarms, as the change of a variable over time very often is...

Nowadays high dimensional data in intensive care medicine can be captured, stored, and retrieved with the help of clinical information systems. Intelligent alarm systems are needed for an adequate bedside decision support, in the course of which the detection of qualitative patterns in physiologic monitoring data such as outliers, level changes, or...

In the face of limited health care resources all over the world, rationing of health care services has reached highest priority in medical, political, social, and ethical discussions. Today, rationing is an inevitable matter of fact in health care. Especially in the most costly areas of modern medicine, such as intensive care, new methods and struc...

In critical care extremely high dimensional time series are generated by clinical information systems. This yields new perspectives of data recording and also causes a new challenge for statistical methodology. Recently graphical correlation models have been developed for analysing the partial associations between the components of multivariate tim...

For the implementation of time-critical decision support al- gorithms in a clinical information system (CIS) a precise relation between medical interventions and effects needs to be established. We evaluated for selected drugs and infusions the relation in time between charted dose and effect on on-line hemodynamic variables. The time of the interv...

The overwhelming flood of data in intensive care medicine precludes consistent judgement of medical interventions by humans. The- refore, computerized decision support is needed to assist the health care professional in making reproducible, high-quality decisions at the bed- side. Traditional expert systems rely on a tedious, labor-intensive and ti...