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Biomedical subjects

J P Giolma

Publications and source records attributed to J P Giolma.

7 recordsLinked to original sources
PubMed1989

Defining respiratory epochs using an adaptive AR filter.

As part of the analysis of respiratory signals, it is usually necessary to define timing events such as the end (beginning) of inspiration and/or the end (beginning) of expiration. Traditional methods using derivatives often require scaling and smoothing to give acceptable results. The work described in this paper has employed an adaptive, lattice structure, Autoregressive (AR) filter to replace the derivatives in locating the end of inspiration and of expiration. The time averaging property of the filter algorithm, together with a variable forgetting factor serves to reduce sensitivity to noise which plagues derivative techniques. In addition, the use of filter coefficients to locate respiratory timing information removes the need for separate scaling. Finally, employing the forgetting factor to define the length of time history observed by the filter permits utilization over a wide range of respiratory rates under program control. The technique is general and versatile enough to be implemented in microprocessor based instrumentation.

Algorithms↗
PubMed1983

Antibody response to pneumococcal vaccine in patients with solid tumors and lymphomas.

Ninety patients with solid tumors or lymphomas were immunized with a polyvalent pneumococcal vaccine. Pre- and postimmunization antibody titers were determined by radioimmunoassay. Treated patients with lymphoma had poor antibody response whether on or off chemotherapy. Patient with chronic lymphocytic leukemia had the lowest antibody titers of all patients groups. Patients with solid tumors had antibody responses which were similar to those of the control population. Those patients who received sequential chemotherapy and immunization had a tendency for higher postimmunization titers than those patients who received simultaneous chemotherapy and immunization, but the difference was not significant. This study suggests that patients with solid tumors would be expected to benefit from pneumococcal immunization, whereas patients with lymphoma immunized after receiving treatment initially would not be expected to develop protective antibody levels. Recovery of antibody formation in patients with non-Hodgkin lymphoma, which may occur in patients with Hodgkin disease, remains to be determined.

Antibodies, Bacterial↗
PubMed1981

Manipulation of ascending aortic pressure and flow wave reflections with the Valsalva maneuver: relationship to input impedance.

Dramatic changes in the shape of pulsatile ascending aortic pressure and flow wave forms occur during the Valsalva maneuver in man. To study these changes, aortic pressure and flow signals were recorded in eight patients using a multisensor catheter. Aortic input impedance was derived during the control, strain and postrelease phases of the Valsalva maneuver. During control, well-defined minima and maxima occurred in the spectral plots of impedance moduli. This pattern was accentuated during the postrelease phase. In contrast, input impedance during strain was almost equal to the characteristic impedance for all harmonics. These results imply that during the control and postrelease phases, strong reflections return to the ascending aorta, but during the strain phase, reflections are minimal, absent or more diffuse. From wave transmission theory, it also follows that pulsatile pressure and flow wave forms should be similar in shape in the absence of reflections and dissimilar in the presence of reflections. This was observed in all eight patients. By provoking changes in the arterial tree during the Valsalva maneuver, the magnitude and timing of wave reflections were significantly altered, resulting in marked changes in the shape of pulsatile aortic pressure and flow wave forms. This study demonstrates the importance of reflections in determining the shape of the arterial pulse.

Adult↗
PubMed1981

Effects of exercise on aortic input impedance and pressure wave forms in normal humans.

The effects of supine bicycle exercise on the input impedance of the ascending aorta were studied in thirteen male subjects undergoing cardiac catheterization, but in whom no cardiovascular disease was found. Ascending aortic flow velocity and pressure were recorded simultaneously from a multisensor catheter with an electromagnetic flow velocity probe and a pressure sensor mounted at the same location. A second pressure sensor at the catheter tip provided left ventricular pressure. Fick cardiac outputs were used to scale the velocity signal to instantaneous volumetric flow. Input impedance was calculated from 10 harmonics of aortic pressure and flow. For each subject, impedance moduli and phases from a minimum of 15 beats during rest and exercise were averaged. Peripheral resistance decreased from a resting value of 1142 +/- 51 (+/- SE) dynes sec/cm5 to 712 +/- 39 dynes sec/cm5 during exercise. Characteristic impedance remained unchanged with a resting value of 47 +/- 4 dynes sec/cm5 and an exercise value of 45 +/- 4 dynes sec/cm5. These results were associated with an increase in aortic pressure (96 +/- 2 to 111 +/- 2 mm Hg) and pulse wave velocity implying a decrease in aortic compliance. An increase in aortic cross-sectional area apparently offsets the effects of these changes in compliance and pulse wave velocity to result in an unchanged characteristic impedance. The increase in pulse wave velocity caused wave reflections to occur earlier during exercise, but the general characteristics of the pressure wave shapes remained unchanged.

Adult↗
PubMed1980

Hemostatic function in cancer patients.

We performed coagulation profiles including a complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (aPTT), and quantitation of fibrinogen, antithrombin III (AT III), plasminogen, and fibrin/fibrinogen degradation products (FDP) on 73 cancer patients. All had solid tumors with clinically documented metastases. Eleven patients had strong clinical and laboratory evidence of disseminated intravascular coagulation (DIC). Fifty-five of the remaining 62 patients had no clinical evidence of serious hemorrhage or thrombosis at the time of testing. Thirty-one (50%) non-DIC patients had no abnormal clotting tests. Our data indicate that a majority of cancer patients, with or without hepatic involvement, are able to maintain normal or near normal hemostatic function in vitro until advanced stage of disease. Deviation from normal for PT, aPTT, or TT, depressed AT III activity, or increased FDP signal the presence of complicating pathophysiologic events such as DIC or cirrhosis. Diminution of fibrinogen level or AT III activity and elevation of FDP are more sensitive indicators of DIC than prolongation of PT, aPTT, or TT.

Adolescent↗