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Biomedical subjects

P Barbini

Publications and source records attributed to P Barbini.

60 records · Page 4Linked to original sources
PubMed1981

[Correlations between membrane and bubble oxygenators in patients treated with or without methylprednisolone. Haemodynamic and metabolic parameters (author's transl)].

We studied 64 patients who underwent cardiac surgery. Hemodynamic and metabolic variables-cardiac index (CI), total peripheral resistances (TSR), oxygen consumption and (VO2), urinary output, alveolar-arterial oxygen difference (delta A-a O2) - were related with oxygenator (bubble or membrane oxygenator) and with treatment (with or without methylprednisolone). 31 patients were perfused with membrane oxygenator (MO), 33 with bubble oxygenator (BO), 13 patients MO and 18 patients, BO were treated with methylprednisolone (mps). The analyzed variables were sampled 15 minutes after the start and one to five times during the perfusion. At first data were analyzed in terms of mean values in whole set of time intervals. Only delta A-a O2 showed statistically significant difference between the MO and the BO group (282 +/- 110 versus 361 +/- 82, p less than 0.005). Between nomps-treated and mps-treated patients statistically significant difference were found in TSR (2.134 +/- 362 versus 1.785 +/- 317, p less than 0.005) and in delta A-a O2 (293 +/- 92 versus 355 +/- 108, p less than 0.02). Secondo analysis is concerning time change of variables. The time behaviour of TSR is similar in all groups studied, but a statistically significant lower value was found in mps-treated patients in every time interval. The VO2, in the last time interval, is statistically higher in the mps-treated than in the nomps-treated patients (p less than 0.05) and furthermore, for the same temperature change, the rise of VO2 is higher in the mps-treated (p less than 0.001). The delta A-a O2 shows time increase both in the MO and in the BO group, but the MO patients start from statistically significant lower values than the BO and the behaviours remain parallel for all analyzed time. The results are interpreted and discussed in relation to hemodynamic and metabolic patterns of perfusion as good or bad tissue perfusion.

Cardiac Surgical Procedures↗
PubMedDate not supplied

A new approach for tracking respiratory mechanical parameters in real-time.

A new recursive least-squares procedure for on-line tracking of changes in viscoelastic properties of respiratory mechanics is proposed and applied to artificially ventilated patients. Classical least-squares methods based on simple first-order linear models with time-constant parameters generally provide systematic residuals that hardly satisfy standard statistical tests for model validation in terms of residuals. On the other hand, high order and/or nonlinear models introduce parameters whose estimates are of difficult interpretation in a clinical context. The present procedure overcomes these limitations by using the well-known first-order model of respiratory mechanics, wherein variability of resistance and elastance during the breathing cycle is allowed to take into account nonlinear and high-order behavior. Mean and standard deviation of resistance and elastance estimates, relative to a respiratory cycle, are then determined recursively. Feasibility of the method is evaluated by applying it both to experimental and simulated pressure-airflow signals measured in an intensive care unit during mechanical ventilation of patients recovering from heart surgery. Results demonstrate that the proposed procedure provides data description satisfying statistical tests, such as residual whiteness, and reliable estimates of viscoelastic lung parameters even during substantial and fast variations in the respiratory status. In addition, unlike classical methods, the new technique provides the means for on-line evaluation of parameter variability during each respiratory cycle, by the estimate of their standard deviations. This is important in clinical practice, because only the knowledge of reliable parameter values and standard deviations enables significant changes in the respiratory viscoelastic characteristics, and thus in patient status, to be assessed.

Airway Resistance↗
PubMedDate not supplied

Variable selection for the classification of postoperative cardiac patients.

A set of 13 extensively used hemodynamic, ventilatory and gas analysis variables are measured (on-line or off-line) on 200 patients in an intensive care unit (ICU) during the 6 h immediately following cardiac surgery. Since the existence of two well-separated classes of low- and high-risk patients has been previously shown the divergence criterion is then used to identify those variables which, at three equidistant observation times, possess the greatest separation power. Such variables always include the cardiac index (CI), representative of cardiac performance, and two indices related to respiratory efficiency and metabolic rate, i.e. the carbon dioxide production index (VCO2I) and the arterio-venous oxygen difference (avO2D). The Fisher linear classifier, utilizing these three features, is then tested by using the rotation method. The results show good performance of the linear classifier, which exhibits a probability of correct recognition always greater than 87%, thus suggesting the possibility of obtaining interesting improvements by means of more sophisticated classifiers.

Blood Pressure↗
PubMedDate not supplied

[Evaluation by EMI CT 5005 Scanner of bone mineral contents variations. A proposed skeletal index for clinical use (author's transl)].

Two groups of subjects, ranging from 20 to 40 years of age the first and from 65 to 85 years the second, have been submitted to bone density measurements by EMI CT 5005 All-Purpose Scanner (140 kV; 28 mAs) and the average values compared. The difference between the average values of the two groups has been taken as a scale of points to evaluate the mineral contents of bone. By the group of older subjects the loss in trabecular bone (lumbar spine L2/L3) proved to be 59.51 EMI units, corresponding to the 47.6% of the mineral contents (p = < 0.01); the loss in compact bone (femur) was 6.6 EMI units corresponding to 5.28% of the mineral contents (p = < 5). The trabecular bone and compact bone average values added together give a whole-skeleton mineral contents index. This index applied to the group of older subjects showed a diminution of 65.81 EMI units indicating a 52.6% loss of mineral contents. Repeated measurements taken at a distance of time proved the method to be fairly reliable with acceptable degree of accuracy (+/- 5%). A tentative approach to clinical use of the skeletal index gave satisfying results.

Absorptiometry, Photon↗