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Biomedical subjects

J S Gravenstein

Publications and source records attributed to J S Gravenstein.

At least 19 recordsLinked to original sources
PubMed2006

An integrated coronary circulation teaching model.

OBJECTIVES: We present in this paper a model of the coronary circulation. This model is integrated with a model of the systemic circulation, and contains models for oxygen supply and demand. METHODS: Three compartments are created: one for the right ventricle, one for the epicardial segment of the left ventricle and one for the endo-cardial segment of the left ventricle. The model was implemented in the Java programming language and contains a visual representation of the left and right ventricles which beat in real time. Color shading is used to represent the partial pressure of oxygen in the segments. A multitude of model parameters can be changed to simulate different scenarios. RESULTS: The output of the model was characterized under different conditions and the results verified by clinicians. CONCLUSIONS: Educational models of human physiology can be very useful for a more in depth understanding of complete physiologic systems. The models must however have enough complexity, interaction with other systems, and realism to show the concepts being taught.

Blood Flow Velocity↗
PubMed2002

Safety in anesthesia.

The specialty of anesthesiology has made extraordinary advances in anesthesia safety. Yet, anesthetic mortality and morbidity continue to be far from tolerable. Efforts to enhance safety in anesthesia must include adherence to explicit and implicit safety standards, must make use of equipment that offers modern safety features, must seek to detect and correct developing safety threats as early as possible and must have a structured system to analyze problems and to institute remedies to prevent their recurrence.

Anesthesia↗
PubMed2000

How does human error affect safety in anesthesia?

Anesthesia morbidity and mortality, while acceptable, are not zero. Most mishaps have a multifactorial cause in which human error plays a significant part. Good design of anesthesia machines, ventilators, and monitors can prevent some, but not all, human error. Attention to the system in which the errors occur is important. Modern training with simulators is designed to reduce the frequency of human errors and to teach anesthesiologists how to deal with the consequences of such errors.

Anesthesia↗
PubMed1998

Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD investigators. International Study of Post-Operative Cognitive Dysfunction.

BACKGROUND: Long-term postoperative cognitive dysfunction may occur in the elderly. Age may be a risk factor and hypoxaemia and arterial hypotension causative factors. We investigated these hypotheses in an international multicentre study. METHODS: 1218 patients aged at least 60 years completed neuropsychological tests before and 1 week and 3 months after major non-cardiac surgery. We measured oxygen saturation by continuous pulse oximetry before surgery and throughout the day of and the first 3 nights after surgery. We recorded blood pressure every 3 min by oscillometry during the operation and every 15-30 min for the rest of that day and night. We identified postoperative cognitive dysfunction with neuropsychological tests compared with controls recruited from the UK (n=176) and the same countries as study centres (n=145). FINDINGS: Postoperative cognitive dysfunction was present in 266 (25.8% [95% CI 23.1-28.5]) of patients 1 week after surgery and in 94 (9.9% [8.1-12.0]) 3 months after surgery, compared with 3.4% and 2.8%, respectively, of UK controls (p<0.0001 and p=0.0037, respectively). Increasing age and duration of anaesthesia, little education, a second operation, postoperative infections, and respiratory complications were risk factors for early postoperative cognitive dysfunction, but only age was a risk factor for late postoperative cognitive dysfunction. Hypoxaemia and hypotension were not significant risk factors at any time. INTERPRETATION: Our findings have implications for studies of the causes of cognitive decline and, in clinical practice, for the information given to patients before surgery.

Abdomen↗
PubMed1998

[Monitoring in anesthesiologic practice].

Monitoring has made great strides in the last half century. It enables us to titrate drugs to the desired effect, warns us of impending danger, and helps with the diagnosis of problems confronting our patients. Beyond that it has enormously increased our understanding of anesthetic pathophysiology. Modern monitors, however, are still focused on single variables; they do not provide the panoramic view offered by our senses. They do not give data on the patient's appearance, movement, or position. The clinician incorporates that type of information with the data provided by the monitors and melds that with a much richer information about the system in which the operates, the colleagues with whom he works and the circumstances that affect his patient. Even though we appreciate the importance of that wealth of information, we lack scientific tools to measure its value.

Anesthesia↗
PubMed1998

TWITCHER: a device to stimulate thumb twitch response to ulnar nerve stimulation.

OBJECTIVE: To design and fabricate a device to simulate evoked thumb adduction in response to ulnar nerve stimulation. METHODS: We implemented a computer-controlled, motorized thumb (TWITCHER) that responds to ulnar nerve stimulation by an unmodified peripheral nerve stimulator. Clinically realistic response patterns are generated for both depolarizing and non-depolarizing muscle relaxants and three modes of stimulation (single twitch, train-of-four, tetanus). RESULTS: The device has been used in a full-scale patient simulator for the last six years. DISCUSSION: TWITCHER has been well received by participants in simulation exercises including the use of neuromuscular blocking drugs.

Electric Stimulation↗
PubMed1998

Influence of pulse oximetry and capnography on time to diagnosis of critical incidents in anesthesia: a pilot study using a full-scale patient simulator.

OBJECTIVE: Many studies (outcome, epidemiological) have tested the hypothesis that pulse oximetry and capnography affect the outcome of anesthetic care. Uncontrollable variables in clinical studies make it difficult to generate statistically conclusive data. In the present study, we eliminated the variability among patients and operative procedures by using a full-scale patient simulator. We tested the hypothesis that pulse oximetry and capnography shorten the time to diagnosis of critical incidents. METHODS: A simulator was programmed to represent a patient undergoing medullary nailing of a fractured femur under general anesthesia and suffering either malignant hyperthermia, a pneumothorax, a pulmonary embolism or an anoxic oxygen supply. One hundred thirteen anesthesiologists were randomly assigned to one of two groups of equal size, one with access to pulse oximetry and capnography data and the other without. Each anesthesiologist was further randomized to one of the four critical incidents. Each anesthetic procedure was videotaped. The time to correct diagnosis was measured and analyzed. RESULTS: Based on analysis of 91 of the subjects, time to diagnosis was significantly shorter (median of 432 s vs. >480 s) for the anoxic oxygen supply scenario (p = 0.019) with pulse oximetry and capnography than without. No statistical difference in time to diagnosis was obtained between groups for the other three critical incidents. CONCLUSIONS: Simulation may offer new approaches to the study of monitoring technology. However, the limitations of current simulators and the resources required to perform simulator-based research are impediments to wide-spread use of this tool.

Anesthesia, General↗
PubMed1997

Computerized pre-anesthetic evaluation results in additional abstracted comorbidity diagnoses.

OBJECTIVE: To study the impact of information from a physician-entry computerized preanesthetic evaluation system on the coding of International Classification of Diseases (ICD-9-CM) diagnoses and on hospital reimbursement due to alterations in diagnosis-related group (DRG) codes. METHODS: Nonrandomized, unblinded trial conducted at a 570-bed university tertiary care hospital. First without and then with reference to information contained on computer-based preanesthetic evaluation reports, medical charts were coded by the study institution's usual professional codes for ICD-9-CM discharge diagnoses and DRG assignment. RESULTS: For 22 of 180 charts studied (12%, 95% confidence limits 7.4% to 16.7%), at least one ICD-9-CM diagnosis was added. Three of 84 DRG-based reimbursements were altered, increasing hospital reimbursement by 1.5%. CONCLUSIONS: Supplemental information from a physician-entered, problem-oriented, computerized preanesthetic evaluation system improved discovery of diagnoses in the population studied.

Anesthesia↗
PubMed1994

Write it right.

Explore the source record for details and available documents.

Publishing↗
PubMed1994

The efficiency of preoperative evaluation: a comparison of computerized and paper recording systems.

OBJECTIVE: We designed and implemented a preoperative evaluation record system with seven networked computers for use by physicians and other medical staff. This study compared the efficiency of the new computerized system with that of the paper system. METHODS: We reviewed data from preoperative evaluations completed from November 1990 through December 1992. Data were analyzed automatically (Borland C program) for two intervals: (1) the waiting period, defined as the time the patient entered the waiting room until he or she entered the examination room; and (2) the examination period, defined as the time the patient entered the examination room until an evaluation form was printed. Data were obtained for 2,511 evaluations on paper and 8,342 by computer. RESULTS: The average waiting period with the paper system was 56.1 +/- 44.8 min; the average waiting period with the computerized system was 59.1 +/- 47.0 min. The average examination period was nearly identical for both systems: 27.5 +/- 23.6 min for the paper system; 28.5 +/- 22.7 min for the computerized system. CONCLUSION: The computerized system required no more examination time than the manual system. In addition, we speculate that time is saved at other points of patient care by the legible, instantly retrievable preoperative evaluations that the computerized system produces.

Hospital Information Systems↗