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PubMedDate not supplied

[An algorithm of respiratory management in the complex treatment and prevention of acute pulmonary lesions in patients with impairments of the central nervous system].

The authors elaborated an algorithm of respiratory management (RM) based on the correlation of RM parameters with the actual and proper thoracopulmonary compliance (C). The algorithm was tested on 42 patients with affections of the central nervous system (CNS) due to severe craniocerebral trauma, spinal trauma, cerebral stroke and multitrauma. Thirty-nine case-matching patients where in the control group--the routine RM algorithm was used for them. Mean pressure in the respiratory paths (Pmean, C, PaO2/FiO2 and rSO2 readings by the Glasgow coma scale, cerebral perfusion pressure, and consumption of sedatives, muscle relaxants and vasopressins as well as frequency rate of acute pulmonary lesions (APL) were registered. The RM algorithm provided for a more effective prevention and treatment of APL versus the routine RM--it cut, 3-fold, the remote APL. With the above RM algorithm, the need in sedatives, muscle relaxants and vasopressins went down from day 2. Positive trends in the neurological status as well as normalized rSO2 were observed earlier versus the controls. Finally, its use ensured a more favorable treatment outcome.

Adult↗

PubMed2004

Objective evaluation of three-dimensional image registration algorithms--tools for optimization and evaluation.

OBJECTIVE: The registration of medical volume data sets plays an important role when different images or modalities are used during computer-assisted surgical procedures. Nevertheless, it is often questionable how robust and accurate the underlying algorithms really are. Therefore, the goal is to foster the establishment of methods for an objective evaluation. METHOD: To reliably calculate the accuracy of registration algorithms, a reference transformation must be known. Due to the unknown perfect registration for real clinical data, the simulation of realistic data and successive affine transformations are employed. The simulation is based on models of the respective imaging modality where the dominant physical effects are taken into account. This gives the user full control over all simulation and transformation parameters. Finally, suitable quality measures are applied which allow a systematic evaluation of image registration accuracy by comparing the known theoretical result and the transformation calculated by the algorithm under investigation. RESULTS: During the development of a new registration algorithm, the presented method proved to be a very valuable tool for optimization and evaluation of registration accuracy, since it allows objective numerical comparison of the calculated results. CONCLUSIONS: The presented method can be used during the development of algorithms for optimization and for quantitative comparison of different registration schemes. The respective software tool can automatically generate and transform simulated but realistic data. Employing suitable numerical quality measures, an objective evaluation of registration results can be easily obtained. Still, the validity of the relatively simple models has to be verified to draw reliable conclusions with respect to real data.

Algorithms↗

PubMed1992

Computer-assisted analysis of mixtures (C.A.MAM): statistical algorithms.

This paper presents various algorithmic approaches for computing the maximum likelihood estimator of the mixing distribution of a one-parameter family of densities and provides a unifying computer-oriented concept for the statistical analysis of unobserved heterogeneity (i.e., observations stemming from different subpopulations) in a univariate sample. The case with unknown number of population subgroups as well as the case with known number of population subgroups, with emphasis on the first, is considered in the computer package C.A.MAN (Computer Assisted Mixture Analysis). It includes an algorithmic menu with choices of the EM algorithm, the vertex exchange algorithm, a combination of both, as well as the vertex direction method. To ensure reliable convergence, a step-length menu is provided for the three latter methods, each achieving monotonicity for the direction of choice. C.A.MAN has the option to work with restricted support size-that is, the case when the number of components is known a priori. In the latter case, the EM algorithm is used. Applications of mixture modelling in medical problems are discussed.

Algorithms↗

PubMed2005

[Application of Burg algorithm in time-frequency analysis of Doppler blood flow signal based on AR modeling].

The Doppler blood flow signal is inherently a nonstationary Gaussian random process whose time-frequency representation associates with the time-varying velocity of blood flow and its variations. With the assumption that the signal being analyzed is stationary during a short time interval, we can not get Doppler time-frequency representations with satisfactory time and frequency resolution. AR modeling based on Levinson-Durbin algorithm has been used to generate time-frequency representations of Doppler blood flow signals. But the errors of the parameters computed by the algorithm will be aggrandized by the shortening of the time interval. Burg has advanced an algorithm, which computes the parameters by making the sum of forward and backward forecasting errors minimum. In the paper, time-frequency representations computed by Burg and Levinson-Durbin algorithm were compared with the theoretical representation. We found that the time-frequency representations computed by Burg algorithm are more similar to the theoretical representation, especially in frequency band.

Algorithms↗

PubMed2005

Addressing the need for a simpler algorithm for the management of women with urinary incontinence.

AIMS: Urinary incontinence (UI) is a prevalent and bothersome condition for many women. However, few women convey the problem to primary care physicians (PCPs), and few PCPs proactively ask about it. One reason may be that available UI recommendations are too complex and difficult to implement. Simplification may encourage greater adaptation as long as a simplified algorithm does not compromise patient safety. I review the opportunity to develop a simpler UI algorithm based on the 3rd edition 2005 International Consultation of Incontinence (ICI) guidelines for the initial management of UI in women. METHODS: A literature search for scientific evidence supporting simplification was performed using PubMed, the Cochrane Database, the Agency for Health Care Policy and Research's (AHCPR) 1996 recommendations, and the ICI's 2005 Incontinence Book / CD-ROM. Each level in the ICI algorithm for initial assessment and treatment was evaluated to develop an updated and less complex management strategy. RESULTS: A simpler UI algorithm for PCPs should focus on considering reversible risk factors and identifying those who need specialized management. A short questionnaire may be sufficient to assess type and severity of UI, whereas a standard neurologic or comprehensive abdominal and pelvic examination seems unnecessary. Treatment should be restricted to a few evidence-based options. CONCLUSIONS: In conclusion, a simpler UI algorithm allows the initiation of evidence-based treatment after a simplified assessment in primary care.

Algorithms↗

PubMed2003

Experimental studies of the Universal Chemical Key (UCK) algorithm on the NCI database of chemical compounds.

We have developed an algorithm called the Universal Chemical Key (UCK) algorithm that constructs a unique key for a molecular structure. The molecular structures are represented as undirected labeled graphs with the atoms representing the vertices of the graph and the bonds representing the edges. The algorithm was tested on 236,917 compounds obtained from the National Cancer Institute (NCI) database of chemical compounds. In this paper we present the algorithm,some examples and the experimental results on the NCI database. On the NCI database, the UCK algorithm provided distinct unique keys for chemicals with different molecular structures.

Algorithms↗

PubMed2006

[A digital subtraction angiography system based on LUT algorithms].

Look-up table (LUT) algorithms have been widely used in digital signal processing, but the article on the application of LUT algorithms in digital subtraction angiography was rarely reported. In this article, the effect of different LUT algorithms on digital subtraction angiography images is introduced. The result reveals that different LUT algorithms can bring about different effects of image. Based on analysis and comparison, we deem it possible to acquire improved images of DSA by use of some LUT algorithms with image processing.

Algorithms↗

PubMed2006

Enhanced real-time cursor control algorithm, based on the spectral analysis of electromyograms.

This paper presents a new version of an EMG-based, hands-free, cursor control system, and compares its performance to that of a previous version. Both systems use classification algorithms that rely on the periodogram estimation of the power spectral density (PSD) of electromyogram (EMG) signals from muscles in the face. The older system requires three electrodes for EMG input, and utilizes an algorithm that calculates partial power accumulations over the frequency ranges of 0Hz - 145Hz and 145Hz - 600Hz in the PSDs of the EMG signals. The new system requires four electrodes for EMG input, and utilizes an algorithm that calculates mean power frequency (MPF) values to assist in distinguishing the cranial muscle that contracted. An experiment was devised to gauge the point-and-click capabilities of both systems. The experimental results were evaluated using Fitts' Law analysis. The results show that the new algorithm provides improved point-and-click performance over the old algorithm.

Algorithms↗

PubMed2005

A fast protein-protein docking algorithm using series expansion in terms of spherical basis functions.

We describe a fast protein-protein docking algorithm using a series expansion in terms of newly designed bases to efficiently search the entire six-dimensional conformational space of rigid body molecules. This algorithm is an ab initio docking algorithm designed to list candidates of putative conformations from a global conformational space for unbound docking. In our algorithm, a scoring function is constructed from terms that are the inner products of two scalar fields expressing individual molecules. The mapping from a molecule to a scalar field can be arbitrarily defined to express an energy term. Since this scoring scheme has the same expressiveness as that of a method using a fast Fourier transform (FFT), it has the flexibility to introduce various physicochemical energies. Currently, we are using scalar fields that approximate desolvation free energy and steric hindrance energy. Fast calculation of the scoring function for each conformation of the six-dimensional search space is realized by expansion of the fields in terms of basis functions which are combinations of spherical harmonics and modified Legendre polynomials, and the use of only low-order terms, which carry most of the information on the scalar field. We have implemented this algorithm and evaluated the computation time and precision by using actual protein structure data of complexes and their monomers. This paper presents the results for six unbound cases and in all the cases we obtained at least one conformation close to the native structures (interface RMSD < 3.0 A) within the top 1000 candidates with about 40 seconds of computation time using a single Pentium4 2.4 GHz CPU.

Algorithms↗

PubMedDate not supplied

An algorithm for the identification of undiagnosed COPD cases using administrative claims data.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major cause of death in the United States, but most persons who have airflow obstruction have never been diagnosed with lung disease. This undiagnosed COPD negatively affects health status, and COPD patients may have increased health care utilization several years before the initial diagnosis of COPD is made. OBJECTIVE: To investigate whether utilization patterns derived from analysis of administrative claims data using a discriminant function algorithm could be used to identify undiagnosed COPD patients. METHODS: Each patient who had a new diagnosis of COPD during the study period (N = 2,129) was matched to as many as 3 control subjects by age and gender. Controls were assigned an index date that was identical to that of the corresponding case, and then all health care utilization for cases and controls for the 24 months prior to the initial COPD diagnosis was compared using logistic regression models. Factors that were significantly associated with COPD were then entered into a discriminant function algorithm. This algorithm was then validated using a separate patient population. RESULTS: In the main model, 19 utilization characteristics were significantly associated with preclinical COPD, although most of the power of the discriminant function algorithm was concentrated in a few of these factors. The main model was able to identify COPD patients in the validation population of adult subjects aged 40 years and older (N = 41,428), with a sensitivity of 60.5% and specificity of 82.1%, even without having information on the history of tobacco use for the majority of the group. Models developed and tested on only 12 months of utilization data performed similarly. CONCLUSION: Discriminant function algorithms based on health care utilization data can be developed that have sufficient positive predictive value to be used as screening tools to identify individuals at risk for having undiagnosed COPD.

Adult↗

PubMed1991

Clinical evaluation of an algorithm for the interpretation of hyperamylasemia.

Total amylase concentration in serum continues to be widely determined in the diagnosis of acute pancreatic disease. Accumulated experience has made clear, however, that this determination has distinct limitations. Consequently, the knowledge of the origin of hyperamylasemia may have an important influence on treatment, hospitalization, and extent of clinical investigations. We undertook a logical and systematic approach to the interpretation of hyperamylasemia through the use of an algorithm that can be applied in clinical situations without the need for the integration of radiologic procedures or clinical data. The proposed algorithm was tested for effectiveness in 97 consecutive hospitalized patients with hyperamylasemia (amylase level greater than twice the upper reference limit) for a 2-year period. The majority (52.5%) of these patients had acute pancreatitis. The algorithm assigned the correct diagnostic categories in 95.8% of cases, with a disagreement between patient diagnosis and algorithm-generated diagnosis in only four cases. These four patients (two with acute biliary disease, one with bacterial peritonitis, and one with chronic renal failure) had pancreatic lipase values greater than five times the upper reference limit, so that the algorithm classified their condition as acute pancreatitis. The clinical trial indicated that the proposed decision tree, which requires only knowledge of biochemical data that are readily available, is useful in the evaluation of elevated amylase activity and facilitates arrival at a definitive diagnosis.

Acute Disease↗

PubMed2006

[Semi-analysis algorithm to retrieve pigment concentrations in the red tide area of the East China Sea].

For the purpose of detecting and forecasting research of red tides to reduce the loss, a semi-analytic algorithm to retrieve chlorophyll-a concentrations was established in the area where red tides often brought out, according to the data collected during the red tides cruise in the East China Sea in April 2002. In the algorithm, empirical equations were made based on the coefficients from the in-situ data, including the optical properties of the research area. The in-situ data were used to validate the algorithm. The discrepancy of chlorophyll-a absorption coefficients and concentrations are mainly located in the region of 30%. The root mean deviation of the chlorophyll-a concentrations between the observed and the calculated is 0.24, the maximum relative deviation 40.93%, the mean relative deviation 18.83% and the correlation coefficient 0.83. The results show that the precision of the algorithm is high and the algorithm is fit for the research area.

Algorithms↗

PubMed2006

Evaluation of simple clinical signs of illness in young infants (0-2 months) and its correlation with WHO IMCI algorithm (7 days to 2 months).

OBJECTIVE: To evaluate simple clinical signs of illness in young infants (0 to 2 months) and to correlate with WHO IMCI algorithm (7 days-2 months). DESIGN: Prospective observational. Study conducted in the outpatient department and emergency room of a pediatric tertiary level hospital. METHODS: Four hundred and ninety seven young infants (0 to 2 months) presenting to outpatient department or emergency room were recruited. Detailed history, clinical examination including all signs in IMCI algorithm was recorded in the pre-designed proforma. The study subjects were investigated and managed according to the protocol of treating unit, which served as gold standard. The diagnostic and therapeutic agreement between the gold standard and IMCI was computed. The study subjects were analyzed as one age group (0 to 2 months) and also after de- segregating into early and late neonatal age group (0 to 7 days and 7 days to 2 months age). RESULTS: Mean number of illnesses in 0 to 7 days, 7 days-2 months and 0-2 months groups were 1.97, 2.0 and 2.02 respectively. Those who required referral as per IMCI algorithm had higher proportion of co-morbidities. The referral criteria were fairly sensitive (78 to 85 percent) in predicting hospitalization with moderately high specificity (78 percent). Diagnostic agreement between gold standard and IMCI module was complete in 57 to 68 percent. Amongst diagnostic mismatch, under-diagnosis was found more frequently (72 to 82 percent) than over-diagnosis (17 to 29 percent). The sensitivity of algorithm to identify serious bacterial infections was quite high (96 to 98 percent) with moderately good specificity (80 to 92 percent). Jaundice was single most important complaint accounting for 47 to 62 percent of diagnostic mismatch. CONCLUSION: IMCI algorithm appears to be a promising, feasible and useful intervention strategy to triage and treat young infants in 7 days-2 months age group. This tool remains effective even when extended to 0 to 7 days age group. However a further increase in its sensitivity can be achieved by including yellowness of lower extremities/ palms/ soles as a criterion.

Algorithms↗

PubMed1991

A computational model of approximate Bayesian inference for associating clinical algorithms with decision analyses.

The lack of rationale or explanation is a major deficiency of clinical algorithms. To address this issue, the authors present a computational model for associating decision analyses with clinical algorithms. Automata theory is used to model categorical reasoning with approximate Bayesian inference based on probability intervals. This approximation reduces the number of computations to linear-order instead of the exponential-order combinations of clinical findings in exact Bayes. The linkage of decision analyses and clinical algorithms by means of this model exploits a new concept of "regular" clinical algorithms and their equivalency in theory and provides valuable perspectives in practice for developers of clinical algorithms.

Algorithms↗

PubMed1990

[A comparison of two algorithms for determining renal whole body clearance following simultaneous acquisition with a partially shielded whole-body counter and a gamma camera].

The influence of instrumentation, algorithm, and the time of blood sampling on whole-body renal clearance as defined by effective renal plasma flow (ERPF) was investigated. The study involved simultaneous sampling with a partially shielded whole-body counter (WBC) and a gamma camera to assess ERPF. The results obtained using two different analysis algorithms for each modality are compared. Although ERPF as determined by the Oberhausen technique was significantly higher than that obtained using an algorithm developed by the authors, for each algorithm there was no significant difference between the WBC and gamma camera-derived values within the range of 100 to 800 ml/min. Furthermore, positioning of the ROI was not critical for gamma camera-derived ERPF (SD less than 1% for multiple crescentic ROIs and approximately 4% for multiple rectangular ROIs). However, the time of blood sampling did appear more important since the average ERPF derived from the 10- and 20-min samples compared with that from the 15- and 25-min samples differed significantly for both analysis algorithms. The methodology which we have validated provides a more precise tool for further investigations of the influence of medication, posture, and exercise stress on renal function.

Algorithms↗

PubMed1988

Performance of two new algorithms for estimating within- and between-method carryover evaluated statistically.

Accurate and precise algorithms for estimating within-method carryover, based on the minimization of a unique "carryover sum of squares," and between-method carryover, based on a weighted Deming regression of first sample recovery vs carryover-corrected "true" recovery, are described and compared with traditional methods by use of a Monte Carlo study. In addition, I have studied the experimental parameters that influence the accuracy and precision of carryover estimation. The new algorithm for estimating within-method carryover is unbiased under most conditions, whereas the traditional algorithm is biased low under most conditions. The new algorithm is also more precise, owing to more-efficient utilization of information contained in an analytical run performed for carryover estimation. Between-method carryover in a random-access analyzer is estimated quantitatively by the second proposed algorithm and is found to be readily and precisely determinable. Use of these methods in combination to evaluate analytical interaction should allow the prediction of carryover error under most current analytical situations.

Algorithms↗

PubMed1986

Pitfalls in the use of clinical algorithms.

The algorithm is a very useful tool in medical practice. Like any other tool, it has advantages and disadvantages. The wise physician avoids a modality until he has learned how to use it. The same should be true of algorithms. Obtain some computer primers that explain the writing of algorithms. Experiment with algorithms of your own creation. When you reach the level where you can easily write your own algorithms, you are ready to use those written by others, making any modifications necessary to suit your own philosophy and experience.

Algorithms↗

PubMed1995

An optimized parsing algorithm well suited to RNA folding.

The application of stochastic context-free grammars to the determination of RNA foldings allows a simple description of the sub-class of sought secondary structures, but it needs efficient parsing algorithms. The more classic thermodynamic model of folding, popularized by Zuker under the framework of dynamic programming algorithms, allows an easy computation of foldings but its use is delicate when constraints have to be introduced on sought secondary structures. We show here that S-attribute grammars unify these two models and we introduce a parsing algorithm whose efficiency enables us to handle problems until then too difficult or too large to deal with. As a matter of fact, our algorithm is as efficient as a standard dynamic programming one when applied to the thermodynamic model (yet it offers a greater flexibility for the expression of constraints) and it is faster and saves more space than other parsing algorithms used so far for stochastic grammars.

Algorithms↗