Diagnosis of complex acid-base disorders: physician performance versus the microcomputer

ABG Assistant-Towards an Understanding of Complex Acid-Base Disorders

The ability to diagnose acid-base imbalances correctly is essential for physicians and other healthcare workers. Despite its importance, it is often considered too complex and confusing. Although most people dealing with arterial blood gases (ABGs) do not usually have problems with acid-base disorder assessment, such an analysis is also carried out by other healthcare workers for whom this can be a challenging task. Many aspects may be problematic, partly due to multiple data analysis methods and no definitive statement on which one is better. According to our survey, the correctness of arterial blood gas analysis is unsatisfactory, especially in mixed disorders, which do not always manifest an obvious set of symptoms. Therefore, ABG parameters can be used as an established biomarker panel, which is considered to be a powerful tool for personalized medicine. Moreover, using different approaches to analyze acid-base disorders can lead to varying diagnoses in some cases. Because of these problems, we developed a mobile application that can spot diagnostic differences by taking into account physiological and chemical approaches, including their variants, with a corrected anion gap. The proposed application is characterized by a high percentage of correct analyses and can be an essential aid for diagnosing acid-base disturbances.

Development of a computer-interpretable clinical guideline model for decision support in the differential diagnosis of hyponatremia

INTRODUCTION

Hyponatremia is the most common type of electrolyte imbalance, occurring when serum sodium is below threshold levels, typically 135mmol/L. Electrolyte balance has been identified as one of the most challenging subjects for medical students, but also as one of the most relevant areas to learn about according to physicians and researchers. We present a computer-interpretable guideline (CIG) model that will be used for medical training to learn how to improve the diagnosis of hyponatremia applying an expert consensus document (ECDs).

METHODS

We used the PROForma set of tools to develop the model, using an iterative process involving two knowledge engineers (a computer science Ph.D. and a preventive medicine specialist) and two expert endocrinologists. We also carried out an initial validation of the model and a qualitative post-analysis from the results of a retrospective study (N=65 patients), comparing the consensus diagnosis of two experts with the output of the tool.

RESULTS

The model includes over two-hundred "for", "against" and "neutral" arguments that are selectively triggered depending on the input value of more than forty patient-state variables. We share the methodology followed for the development process and the initial validation results, that achieved a high ratio of 61/65 agreements with the consensus diagnosis, having a kappa value of K=0.86 for overall agreement and K=0.80 for first-ranked agreement.

CONCLUSION

Hospital care professionals involved in the project showed high expectations of using this tool for training, but the process to follow for a successful diagnosis and application is not trivial, as reported in this manuscript. Secondary benefits of using these tools are associated to improving research knowledge and existing clinical practice guidelines (CPGs) or ECDs. Beyond point-of-care clinical decision support, knowledge-based decision support systems are very attractive as a training tool, to help selected professionals to better understand difficult diseases that are underdiagnosed and/or incorrectly managed.

Heimlich trauma: a violent maneuver

The Heimlich maneuver is a life-saving technique for dislodging foreign material from the respiratory tract. This report illustrates intraabdominal injuries, including a large mesenteric laceration, mesenteric contusions, and intraperitoneal hemorrhage, that occurred in a recipient of a vigorously applied Heimlich maneuver. The potential for confusing such injuries with homicidally inflicted injuries is emphasized.

The development and implementation of an expert system for the analysis of umbilical cord blood

An assessment of neonatal outcome may be obtained from analysis of blood in the umbilical cord of the infant immediately after delivery. This can provide information on the health of the newborn infant, guide requirements for neonatal care, and is recommended practice of the Royal College of Obstetricians and Gynaecologists. However, there are problems with the technique. Samples frequently contain errors in one or more of the important parameters, preventing accurate interpretation and many clinical staff lack the expert knowledge required to interpret error-free results. In this paper the development and implementation of an expert system to overcome these difficulties is described. The expert system validates results, provides a textual interpretation and archives all results to database for audit, research and medico-legal purposes. The system has now been in routine clinical use for over 3 years in Plymouth, and has also been installed in several other hospitals in the UK. Results are presented in which the types and frequency of errors are established and the user acceptance of the system is determined.

A microcomputer teaching and decision-support system for emergency medicine: use of hypermedia and artificial intelligence in combination

Hospital emergency units are submitted to a continuous intensive and polyvalent practice of medicine. In addition to the few experienced physicians, the medical staff is often made up of young and unskilled students and residents. The ability to reach at any time a wide and flexible knowledge is of the utmost importance to improve the quality of care given to patients and to perfect bedside teaching. The purpose of this work was to present a computerized system, a kind of shell, using, in combination, artificial intelligence and hypertext/hypermedia tools. A modular architecture is presented integrating two entities: an illustrated encyclopedic hypertext network and several expert modules based on production rules concerning well-limited fields of medicine (basic clinical problem-solving, metabolic and acid-base disorders). An interface using the World Wide Web (WWW) will soon be proposed.

The delta (delta) gap: an approach to mixed acid-base disorders

The anion gap (AG) is a helpful, yet underused, clinical tool. Not only does the presence of a high AG suggest a certain differential, but knowledge of the relationship between the rise in AG (delta AG) and the fall in bicarbonate (delta HCO3) is important in understanding mixed acid-based disorders. Simple arithmetic converts this relationship into a numerical value, the delta gap (delta gap). The delta gap = delta AG - delta HCO3. If the delta gap is significantly positive (greater than +6), a metabolic alkalosis is usually present because the rise in AG is more than the fall in HCO3. Conversely, if the delta gap is significantly negative (less than -6), then a hyperchloremic acidosis is usually present because the rise in AG is less than the fall in HCO3. Familarity with the relationship between the changes in AG and HCO3 can be useful in unmasking occult metabolic disorders.

Computer aided interpretation of acid-base disorders

This paper describes an expert system for the interpretation of acid-base disorders. The target users are residents in training in internal medicine, anaesthesia and intensive care medicine. The program is written in PROLOG and runs on a SUN 3/160 minicomputer. Evaluation of a learning set (N = 202) and a test set (N = 194) has proved that the system's accuracy is acceptable. As a result, the program has recently been put in routine clinical practice.

Disorders of acid-base balance

Acid-base disorders are common in sick children. This article is a practical guide to the differential diagnosis and treatment of simple and mixed acid-base disorders of children. Special attention is given to fundamentals of acid-base physiology, to clinical use of the Henderson equation, and to interpretation of readily available laboratory tests.