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Biomedical subjects

U E Ruttimann

Publications and source records attributed to U E Ruttimann.

At least 37 records · Page 2Linked to original sources
PubMed1996

Monitoring the source of memory in detoxified alcoholics.

The ability to monitor the source of remembered information and related reflective cognitive processes was examined in normal volunteers and detoxified alcoholics. Normal volunteers were very accurate judges of whether remembered events were presented as stimuli or were self-generated, even when memory was tested 2 days later. In contrast, a subgroup of otherwise cognitively unimpaired alcoholics demonstrated impairments in the ability to track the source of remembered knowledge and were also less able to inhibit intrusion errors in recalling information from memory. These findings provide preliminary evidence of an impairment in cognitive control functions in certain alcoholics. This conclusion is supported by associated findings indicating that, among alcoholics, performance on explicit memory tasks that required reflective cognitive operations were positively correlated with glucose utilization rates in left prefrontal, temporal, and posterior orbital frontal cortical regions.

Adult↗
PubMed1996

Variability in duration of stay in pediatric intensive care units: a multiinstitutional study.

OBJECTIVE: Development of a statistical model to predict length of stay (LOS) in a pediatric intensive care unit (PICU) that adjusts for patient-related risk factors at admission. DESIGN: Randomized selection of sites by cluster sampling from a 1989 national survey of all hospitals with PICUs, stratified for four quality-of-care factors into 16 clusters (size, presence of an intensive care specialist, medical school affiliation, coordination of care). The data collection was prospective in the selected units. PATIENTS: 5415 consecutive medical, surgical, or emergency admissions to 16 PICUs. MEASUREMENTS: Patients: Pediatric Risk of Mortality (PRISM) score for the initial 24 hours, admission diagnosis classified into system and cause of the primary dysfunction, operative status, preadmission care, critical care modalities required during the first 24 hours, age, sex, PICU length of stay, and outcome. PICU sites: admission volume, coordination of care, presence of an intensivist, presence of residents, and number of pediatric ICU and pediatric hospital beds. METHODS: Log-logistic regression analysis of LOS on patient-related and institution-related factors. RESULTS: Significant (p < 0.05) patient-related predictors of LOS included PRISM, 10 diagnostic groups, 3 preadmission factors (operative status, inpatient/outpatient, previous PICU admission), and first-day use of mechanical ventilation. The ratio of observed to predicted LOS varied among PICUs from 0.83 to 1.25, with three PICUs displaying significantly (p < 0.05) shorter and three PICUs longer LOS. The PICU factors associated (p < 0.05) with shorter (5% to 11%) LOS were presence of an intensivist, presence of residents, and coordination of care, whereas an increased ratio of PICU to hospital beds was associated with longer (p < 0.05) LOS. Medical school affiliation, admission volume, number of pediatric hospital beds, and PICU mortality rates did not have statistically significant effects on LOS when adjusted for patient conditions. CONCLUSIONS: The predictor can be used to adjust LOS in PICUs for patient-related risk factors, enabling the comparison of resource utilization among different institutions. Organizational factors known to foster team-oriented care are associated with shorter LOS, whereas increased relative PICU size may pose an incentive to keep PICU beds occupied longer.

Adolescent↗
PubMed1996

Comparison of emergence and recovery characteristics of sevoflurane, desflurane, and halothane in pediatric ambulatory patients.

This study compares the emergence and recovery characteristics of sevoflurane, desflurane, and halothane in children undergoing adenoidectomy with bilateral myringotomy and the insertion of tubes. Eighty children 1-7 yr of age were studied. Thirty minutes prior to the induction of anesthesia, all patients received 0.5 mg/kg midazolam orally. Patients were randomly assigned to one of four groups: Group 1, sevoflurane induction and maintenance (S:S); Group 2, halothane induction and sevoflurane maintenance (H:S); Group 3, halothane induction and maintenance (H:H); or Group 4, halothane induction and desflurane maintenance (H:D). Tracheal intubation was facilitated with the use of a single dose of 0.2 mg/kg mivacurium. A Mapelson D circuit was used, and all patients received N2O:O2 60:40 for induction and maintenance at standardized appropriate fresh gas flow. Ventilation was controlled to maintain normocapnia. End-tidal concentration of anesthetics was maintained at approximately 1.3 minimum alveolar anesthetic concentration (MAC) (halothane: 0.56; sevoflurane: 2.6; desflurane: 8.3) until the end of surgery when all anesthetics were discontinued. Emergence (extubation), recovery (Steward score 6), and discharge times were compared among patients in the four groups using analysis of variance and Newman-Keuls tests P < 0.05 was considered significant. There were no significant differences among the four groups with respect to age, weight, duration of surgery, or duration of anesthesia. Emergence and recovery from anesthesia were significantly faster in the desflurane group (Group 4) compared with the sevoflurane and halothane groups (Groups 1, 2, and 3) (5 +/- 1.6 min vs 11 +/- 3.7, 11 +/- 4.0, 10 +/- 4.0 min and 11 +/- 3.9 min vs 17 +/- 5.5, 19 +/- 7.1, 21 +/- 8.5 min, respectively). There was a significantly greater incidence of postoperative agitation and excitement in patients who received desflurane (55%) versus sevoflurane (10%) and halothane (25%). There were no significant differences among the four groups with respect to the time to meet home discharge criteria (134 +/- 36.9, 129 +/- 53.3, 117 +/- 64.6, 137 +/- 22.6 in Groups 1, 2, 3, and 4, respectively), in the time to drink oral fluids (139 +/- 31.6, 136 +/- 53.8, 123 +/- 65.0, 142 +/- 29.4 min, respectively), or in the incidence of postoperative vomiting. It is concluded that, although desflurane resulted in the fastest early emergence from anesthesia, it was associated with a greater incidence of postoperative agitation. Sevoflurane resulted in similar emergence and recovery compared with halothane. Desflurane and sevoflurane did not result in faster discharge times than halothane in this patient population.

Adenoidectomy↗
PubMed1996

Prediction of three outcome states from pediatric intensive care.

OBJECTIVE: To develop a method based on admission day data for predicting patient outcome status as independently functional, compromised functional, or dead. DESIGN: Prospectively acquired development and validation samples. SETTING: A pediatric intensive care unit located in a tertiary care center. PATIENTS: Consecutive admissions (n = 1,663) for predictor development, and consecutive admissions (n = 1,153) for predictor validation. METHODS: Pediatric Risk of Mortality score, baseline Pediatric Overall Performance Category score, age, operative status, and primary diagnosis classified into ten organ systems and nine etiologies were recorded at the time of intensive care unit admission. Predictor was developed by stepwise polychotomous logistic regression analysis for the outcome functional, compromised, and dead. Model fit was evaluated by chi-square statistics; prediction performance was measured by the area under the receiver operating characteristic curve, and classification table analysis of observed vs. predicted outcomes. MEASUREMENTS AND MAIN RESULTS: The resulting predictor included Pediatric Risk of Mortality, baseline Pediatric Overall Performance Category, operative status, age, and diagnostic factors from four systems (cardiovascular, respiratory, neurologic, gastrointestinal), and six etiologies (infection, trauma, drug overdose, allergy/immunology, diabetes, miscellaneous/undetermined). Its application to the validation sample yielded good agreement between the total number expected and the observed outcomes for each state (chi-square = 3.16, 2 degrees of freedom, p = .206), with area indices of 0.96 +/- 0.01 for discrimination of fully functional vs. the combination of the two poor outcome states (compromised or death), and 0.94 +/- 0.02 for discrimination of fully or compromised functional vs. death. The 3 x 3 classification resulted in correct classification rates of 83.2%, 74.4%, and 81.3%, for the outcomes functional, compromised, and death, respectively. CONCLUSIONS: Prediction of three outcome states using physiologic status, baseline functional level, and broad-based diagnostic groupings at admission is feasible and may improve the relevance of quality of care assessment.

Arkansas↗
PubMed1996

PRISM III: an updated Pediatric Risk of Mortality score.

OBJECTIVES: The relationship between physiologic status and mortality risk should be reevaluated as new treatment protocols, therapeutic interventions, and monitoring strategies are introduced and as patient populations change. We developed and validated a third-generation pediatric physiology-based score for mortality risk, Pediatric Risk of Mortality III (PRISM III). DESIGN: Prospective cohort. SETTING: There were 32 pediatric intensive care units (ICUs): 16 pediatric ICUs were randomly chosen and 16 volunteered. PATIENTS: Consecutive admissions at each site were included until at least 11 deaths per site occurred. MEASUREMENTS AND MAIN RESULTS: Physiologic data included the most abnormal values from the first 12 and the second 12 hrs of ICU stay. Outcomes and descriptive data were also collected. Physiologic variables where normal values change with age were stratified by age (neonate, infant, child, adolescent). The database was randomly split into development (90%) and validation (10%) sets. Variables and their ranges were chosen by computing the risk of death (odds ratios) relative to the midrange of survivors for each physiologic variable. Univariate and multivariate statistical procedures, including multiple logistic regression analysis, were used to develop the PRISM III score and mortality risk predictors. Data were collected on 11,165 admissions (543 deaths). The PRISM III score has 17 physiologic variables subdivided into 26 ranges. The variables most predictive of mortality were minimum systolic blood pressure, abnormal pupillary reflexes, and stupor/coma. Other risk factors, including two acute and two chronic diagnoses, and four additional risk factors, were used in the final predictors. The PRISM III score and the additional risk factors were applied to the first 12 hrs of stay (PRISM III-12) and the first 24 hours of stay (PRISM III-24). The Hosmer-Lemeshow chi-square goodness-of-fit evaluations demonstrated absence of significant calibration errors (p values: PRISM III-12 development = .2496; PRISM III-24 development = .1374; PRISM III-12 validation = .4168; PRISM III-24 validation = .5504). The area under the receiver operating curve and Flora's z-statistic indicated excellent discrimination and accuracy (area under the receiver operating curve - PRISM III-12 development 947 +/- 0.007; PRISM III-24 development 0.958 +/- 0.006; PRISM III-12 validation 0.941 +/- 0.021; PRISM III-24 validation 0.944 +/- 0.021; Flora's z-statistic - PRISM III-12 validation = .7479; PRISM III-24 validation = .9225), although generally, the PRISM III-24 performed better than the PRISM III-12 models. Excellent goodness-of-fit was also found for patient groups stratified by age (significance levels: PRISM III-12 = .1622; PRISM III-24 = .4137), and by diagnosis (significance levels: PRISM III-12 = .5992; PRISM III-24 = .7939). CONCLUSIONS: PRISM III resulted in several improvements over the original PRISM. Reassessment of physiologic variables and their ranges, better age adjustment for selected variables, and additional risk factors resulted in a mortality risk model that is more accurate and discriminates better. The large number of diverse ICUs in the database indicates PRISM III is more likely to be representative of United States units.

Adolescent↗
PubMed1995

Head motion during positron emission tomography: is it significant?

High sensitivity for detecting local brain function differences from subsequent PET images acquired at different cerebral stimulation states requires interscan head motion to be minimized. This motion was measured by an optical lever system during scanning (130 min) of 15 subjects in a dual-dose injection study. Despite motion restriction by a face-mask restraint system, rotations in the sagittal and coronal planes (up to 4.1 degrees and 2.4 degrees, respectively) significantly influenced the measured means and variances of local metabolic differences between states. Hence, adjustments for head movement by retrospective, digital slice realignment or, better, real-time corrections are important.

Adult↗
PubMed1995

The relationship between left mainstem bronchial diameter and patient size.

Knowledge of a patient's left mainstem bronchial diameter would provide a useful guide to choosing the appropriate double-lumen tube (DLT) size for that patient. Therefore, the authors investigated the possibility that left bronchial diameter could be predictably estimated from a patient's size and sex. The routine preoperative chest X-rays of 100 adult male and female patients of known age, height, and weight were examined. The left bronchial diameter was measured on the posteroanterior (PA) chest x-ray, and a formula was used to correct for the magnification of intrathoracic structures encountered on the PA view. Multiple linear regression analysis was used to determine whether one or more of the variables (age, sex, height, weight, and body surface area) had a predictable relationship to the left bronchial diameter. The left mainstem bronchial diameter in men and women (mean +/- SD/range) was 12.4 +/- 1.5 mm/9.5 to 15.5 mm, and 10.7 +/- 1.0 mm/9.0 to 14.0 mm, respectively. In female patients, none of the variables was significantly correlated with bronchial diameter. In male patients, age (p = 0.013) and height (p = 0.008) individually produced a statistically significant prediction of endobronchial diameter. The following formula was best predictive of left bronchial diameter in men: diameter (mm) = 0.032 x age (year) + 0.072 x height (cm) -2.043. Applying this formula to mean age 50 who are 158, 172, and 185 cm in height, the predicted left bronchial diameters are 11.0, 12.0, and 13.0 mm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Limitations and withdrawals of medical intervention in pediatric critical care.

OBJECTIVE: To investigate the use and implementation in pediatric intensive care units (PICUs) of three levels of restriction of medical intervention: do not resuscitate (DNR), additional limitations of medical interventions beyond DNR, and withdrawal of care. DESIGN: Consecutive patients admitted between December 1989 and January 1992. SETTING: A total of 16 PICUs randomly selected to represent variability in size, teaching status, and presence or absence of a pediatric intensivist and unit coordination. MAIN OUTCOME MEASURES: Profiles of children undergoing restrictions of medical interventions including the influence of chronic disease, the justifications for restrictions, and description of implementation practices. PATIENTS: All pediatric admissions undergoing restrictions (n = 119) drawn from 5415 consecutive PICU admissions. RESULTS: A total of 94 (79%) of the restriction patients died during the PICU course, representing 38% of all deaths. A total of 73 restrictions (61%) resulted from acute disease, most involving the central nervous system or respiratory system. Restrictions were evenly divided between DNR (39%), additional limitations of medical intervention beyond DNR (27%), and withdrawals of medical intervention (34%). Survival decreased with increasing levels of restriction from 35% of DNR patients to 9% of patients with additional limitations and 2% of withdrawal patients. Imminent death was cited as the justification for restrictions in 70% of cases, no relational potential was cited in 22%, and excessive burden was cited in 8%. CONCLUSIONS: Restrictions of medical intervention were used in all PICUs surveyed. Although severe chronic disease was common among restriction patients, acute disease was the predominant event precipitating placement of restrictions. Imminent death, not quality of life or excessive burden, was the most common justification.

Analysis of Variance↗
PubMed1994

Impact of quality-of-care factors on pediatric intensive care unit mortality.

OBJECTIVE: To determine the importance of the following care factors previously associated with hospital quality on survival from pediatric intensive care: size of the intensive care unit (ICU), medical school teaching status of the hospital housing the ICU, specialist status (pediatric intensivist), and unit coordination. DESIGN: After a national survey, consecutive case series were collected at 16 sites randomly selected to represent unique combinations of quality-of-care factors. SETTING: Pediatric ICUs. PATIENTS: Consecutive admissions to each site. MAIN OUTCOME MEASURE: Patient mortality adjusted for physiologic status, diagnosis, and other mortality risk factors. RESULTS: There were 5415 pediatric ICU admissions and 248 ICU deaths. The ICUs differed significantly with respect to descriptive variables, including mortality (range, 2.2% to 16.4%). Analysis of risk-adjusted mortality indicated that the hospital teaching status and the presence of a pediatric intensivist were significantly associated with a patient's chance of survival. The probability of patient survival after hospitalization in an ICU located in a teaching hospital was decreased (relative odds of dying, 1.79; 95% confidence interval [CI], 1.23 to 2.61; P = .002). In contrast, the probability of patient survival after hospitalization in an ICU with a pediatric intensivist was improved (relative odds of dying, 0.65; 95% CI, 0.44 to 0.95; P = .027). Post hoc analysis indicated that the higher severity-adjusted mortality in teaching hospitals may be explained by the presence of residents caring for ICU patients. CONCLUSION: Characteristics indicative of the best overall hospital quality may not be associated, or may be negatively associated, with quality of care in specialized care areas, including the pediatric ICU.

Child↗
PubMed1994

Decreased cingulate and precuneate glucose utilization in alcoholic Korsakoff's syndrome.

Localized cerebral glucose utilization was determined for nine abstinent alcoholic men with Korsakoff's syndrome and 10 age-matched normal men who underwent positron emission tomography with [18F]2-fluoro-2-deoxyglucose (FDG). Patients with Korsakoff's syndrome showed relatively decreased glucose utilization in cingulate and precuneate areas. These decreases persisted even after correction for group differences in ventricular and sulcal cerebrospinal fluid measured on computed tomography. Electroencephalographic recordings at the time of FDG uptake showed no group differences, a finding that demonstrates that the metabolic differences could not be explained by differences in physiological arousal at the time of scanning. It is concluded that the decreased glucose utilization in the patients reflects a disruption of memory circuitry, the Papez circuit, caused by diencephalic lesions induced by thiamine deficiency.

Aged↗
PubMed1994

Erythropoietin response to critical illness.

OBJECTIVE: To examine the endogenous erythropoietin response in critically ill children with acute anemia or acute hypoxemia. DESIGN: A prospective case study of critically ill acutely anemic, and acutely hypoxemic pediatric patients compared with control groups of critically ill nonanemic and nonhypoxemic patients and with a hemoglobin and age-matched, chronically anemic patient group. SETTING: Multidisciplinary, tertiary, pediatric intensive care unit (ICU). PATIENTS: Critically ill patients admitted to the pediatric ICU during an 11-month period between February 1992 and March 1993 with acute anemia (n = 21), acute hypoxemia (n = 18), or neither anemia nor hypoxemia (n = 10). Outpatients with chronic anemia (n = 21) and no acute illness were also studied as a comparison group. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ages were equivalent among the groups and averaged 57.4 +/- 47.2 months (range 1 to 144). Acutely hypoxemic and critically ill control patients had normal hemoglobin levels. Acutely anemic patients had a hemoglobin level equivalent to chronically anemic outpatients, but lower (p < .001) hemoglobin levels than acutely hypoxemic and critically ill control patients. The serum erythropoietin concentrations in the acutely anemic group were significantly lower than erythropoietin values in the chronically anemic group (39.3 +/- 62.2 vs. 861 +/- 758 mU/mL, p < .001) and similar to erythropoietin concentrations in the critically ill control (13.5 +/- 10.5 mU/mL) and acutely hypoxemic (5.2 +/- 3.3 mU/mL) patient groups. Only ten of 49 critically ill patients had an erythropoietin concentration above normal, compared with 20 of 21 chronically anemic patients, whose erythropoietin concentrations were above normal. CONCLUSIONS: The erythropoietin response to known physiologic stimuli is blunted in critically ill children. This blunted erythropoietin response may result in increased transfusion requirements.

Acute Disease↗
PubMed1994

Statistical approaches to development and validation of predictive instruments.

Concepts underlying the development of prediction models for intensive care unit (ICU) outcome are outlined, special emphasis is placed on multivariate logistic regression analysis. A short exposition to experimental study designs and techniques for predictor validation is given. Two statistical procedures for assessing the degree of agreement between predicted and observed mortality risks are discussed. The use of receiver operating characteristic (ROC) analysis is thoroughly reviewed as a major tool for describing and comparing, graphically and statistically, the accuracy of predictors for classifying patients prospectively into survivors and nonsurvivors.

Decision Support Techniques↗
PubMed1993

A time-series approach to predict outcome from pediatric intensive care.

Daily assessment of the physiologic status of intensive care unit (ICU) patients by a validated score is used to predict their discharge as either alive or dead. Daily scores were decorrelated by time-series analysis techniques to establish a predictor of the next day's score. Data from 3299 patients (290 deaths) in nine different pediatric ICUs were used to derive the predictor model. Using the highest predicted score observed in any survivor from this data base as a threshold value, this predictor correctly identified 21.9% (sensitivity) of the nonsurvivors with no errors in predicting a fatal outcome (100% specificity). This performance is significantly (P < 0.001) better than that with a static predictor based on the first- or second-day scores only (6.6 or 7.4% sensitivity, respectively), or a known empirical dynamic model using the scores of the 2 most recent days (10.3% sensitivity, P < 0.002).

Age Factors↗
PubMed1993

Fully automated segmentation of cerebrospinal fluid in computed tomography.

A method is presented for automated delineation and measurement of cerebrospinal fluid (CSF) regions in computed tomographic (CT) sections. Regions of skull and scalp are removed by using a linear discriminant analysis approach. Beam-hardening artifact is reduced by subtracting from each section the average radial intensity profile, characterized by a polynomial function. Remaining intensity gradients are suppressed by implementing CSF segmentation with a local thresholding technique based on maximum-entropy principles. CSF fractions from 12 regions of interest (ROIs) were measured in 10 patients with alcoholic Korsakoff syndrome and 9 normal volunteers. The same ROIs were also assessed by an interactive segmentation method, which enabled the operator to compensate for beam-hardening distortions by selecting suitable threshold values for each ROI. Both methods identified the same ROIs as displaying statistically significant differences between the two subject groups. However, interactive segmentation underestimated sulcal CSF by 20-70%, which was confirmed by applying both methods to CT scans of an anthropomorphic phantom. Hence, in contrast to interactive thresholding, unsupervised segmentation relies on firmly fixed criteria that reduce the influence of beam-hardening distortions and provide more objective results.

Aged↗
PubMed1992

An experimental study of new diagnostic methods for the examination of osseous lesions in the temporomandibular joint.

Digital subtraction radiography, tomosynthesis, bone uptake of radionuclide, and arthroscopy were evaluated for detection and quantification of bony lesions induced unilaterally in the condyles of six dogs. A stereotaxic head-holder facilitated acquisition of reproducible radiographs suitable for subtraction and for circular tomosynthesis. Bone uptake of technetium-99m methylene diphosphonate was measured with a hand-held collimated miniature detector. Arthroscopy was performed with an arthroscope of 2.4 mm diameter. Bone defect mass determined by subtraction radiography correlated highly (r = 0.92, p less than 0.001) with the calcium content of removed bone measured by atomic spectroscopy. Both subtraction radiography and tomosynthesis indicated reshaping of the condyle into a more anterior position over a 10-week follow-up period. Radionuclide uptake was significantly elevated (p less than 0.04) from 2 to 10 weeks after surgery and correlated (r = 0.73, p less than 0.05) with regained bone mass measured by subtraction radiography. Arthroscopy revealed progressive degeneration of cartilage with denudation in the fossa. Both radiographic techniques demonstrated the lesions and bone remodeling, but only subtraction provided quantitative results. Radionuclide uptake predicted quantitatively future bone mass changes, and arthroscopy revealed cartilage and soft tissue status not otherwise observable.

Animals↗
PubMed1992

Fractal dimension from radiographs of peridental alveolar bone. A possible diagnostic indicator of osteoporosis.

The purpose of this study was to investigate whether a radiographic estimate of osseous fractal dimension is useful in the characterization of structural changes in alveolar bone. Ten dry mandibular bone segments were radiographed from three controlled projection angles (-5, 0, +5 degrees), before and after acid-induced partial decalcification. Fractal dimension was estimated by regression analysis of power spectra computed by Fourier transform of selected regions of interest in digitized images of the radiographs. Repeated-measures ANOVA showed that fractal dimension so determined varied over anatomic locations (p less than .01), but increased after acid-induced demineralization (p less than .0005), irrespective of the radiographic projection angles (p greater than .99). In vivo fractal dimension was computed from randomly selected intraoral radiographs of six premenopausal (ages, 32.8 +/- 3.9) and six postmenopausal (ages, 62.5 +/- 4.1) women. A significantly (p less than .01) higher fractal dimension was observed in the older group.

Adult↗