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Biomedical subjects

M R Neuman

Publications and source records attributed to M R Neuman.

At least 37 records · Page 2Linked to original sources
PubMed1988

Determination of the elastic properties of the cervix.

The elastance of the uterine cervix of nonpregnant women was measured by placing a 3- or 4-cm compliant balloon in the cervical canal and determining its pressure-volume characteristic while filling with up to 5 mL of sterile water at a rate of 12 mL/minute. The mean elastance for 247 patients who had previously suffered either one or more spontaneous midterm pregnancy losses, preterm birth, or three or more early spontaneous abortions was significantly lower than that of 42 controls who did not meet these criteria. Elastances were significantly lower in groups having a clinically observed patulous cervix or laceration, or a clinically diagnosed incompetent cervix, than in the normal cervix group. No significant difference was found between the follicular and luteal phases for 64 regularly cycling women. Values were significantly reduced in women showing a widened cervix on a hysterosalpingogram when compared with those with a normal-appearing cervix. When larger Hegar dilators were passed without resistance, the elastance was generally lower, although there was not always good correlation between the largest dilator passed and elastance.

Catheterization↗
PubMed1987

Pulse oximetry: physical principles, technical realization and present limitations.

Oximetry for continuous patient monitoring has evolved to a mature technology that is clinically useful. Technologic limitations, however, still exist and there is need to develop more reliable, less expensive systems that will allow new applications such as fetal and home infant and adult monitoring. Although it is not possible to fully monitor patient blood gas status with a single variable, pulse oximetry provides an important view of the blood oxygen content that can be combined with other monitoring methods to more fully characterize patient status.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Estimation of the determinants of transcutaneous oxygen tension using a dynamic computer model.

A dynamic model for oxygen transport within the outer layers of the skin and a tcPO2 sensor has been developed. By comparing model simulations with clinical measurements from adults, it is possible to analyze some of the physiologic and physical determinants of the tcPO2 measurement. The results indicate that the permeability of the epidermis is a significant parameter when using a microcathode sensor. Using this model, the values obtained for normalized stratum papillare blood flow and metabolic oxygen consumption of the dermis are higher than those seen for other models.

Adult↗
PubMed1987

Microelectronic sensors for simultaneous measurement of PO2 and pH.

Sensors capable of simultaneous measurement of pH and PO2 in an aqueous solution have been fabricated in planar form using microelectronic technology. Separate potentiometric metal-metal oxide pH and three electrode amperemetric PO2 sensors have been fabricated together on a silicon chip with active surface of 2 x 3 mm. Rhodium-rhodium oxide electrodes operating in a cyclic voltammetry mode have also been studied and show sensitivity to both pH and PO2 in different regions of the voltage swept curve.

Acid-Base Equilibrium↗
PubMed1986

Improvement of the Botstein-Zacharopolous radiation applicator.

The Botstein-Zacharopolous afterloading radiation source has been modified to facilitate its application to patients receiving intracavitary irradiation therapy. A new clamp assembly, in which each ovoid and the tandum can be separately controlled, has been designed and implemented. A study of 74 patients who alternately received the original or the modified applicator showed the time of the application procedure to be significantly less (p less than 0.001) with the modified device than it was with the original instrument. Fewer X rays were required for evaluating the placement of the modified instrument than the original applicator (p = .055).

Brachytherapy↗
PubMed1985

Influence of different prostaglandin applications on cervical rheology.

The softening effect of prostaglandin (PG) on cervical tissue prior to elective pregnancy termination is quantified by a new technique for the measurement of the elastance and relaxation of the cervix. The method is based on the pressure-volume relation of a compliant balloon placed in the cervical canal. These properties have been measured before and after different applications of prostaglandins in 58 patients electively terminating pregnancy. Application techniques used included high pressure jet application of PGE2 into the tissue of the portio uteri and the internal cervical os (120 micrograms), PGE2 and PGF2 alpha in Tylose gel (100 micrograms/0.5 ml); PGE2 as an intracervical tablet (150 micrograms) and PGE2 oral tablets placed into the posterior fornix of the vagina. Significant changes in cervical elastance were seen with the intracervically applied PGE2 in Tylose gel and the vaginally applied PGE2 tablets. The intracervically applied PGE2 gel also gave significant changes in cervical relaxation. No side effects other than mild cramping (2 patients) were seen with any of the applications in this study.

Abortion, Induced↗
PubMed1984

The neonatal oxycardiorespirogram.

The neonatal oxycardiorespirogram is the simultaneous recording of respiration rate, respiration waveform, instantaneous heart rate, transcutaneous oxygen tension, and relative skin perfusion or "blood flow" from newborn infants. It is important in monitoring the high risk infant to assess the cardiovascular and respiratory function of the patient. The techniques for obtaining the various signals of the oxycardiorespirogram are reviewed and the usual method for making this recording is presented. Several examples of typical oxycardiorespirograms are given.

Biomedical Engineering↗
PubMed1983

Spectrophotometric investigation of pulsatile blood flow for transcutaneous reflectance oximetry.

A new method to estimate arterial oxygen saturation is suggested based on the presence of the plethysmographic pulse. A prototype skin reflectance oximeter system utilizing a miniature solid state optical transducer has been constructed. Preliminary data collected from a group of volunteers indicated good quantitative correlation between skin reflectance and arterial oxygen saturation as determined by an earlobe oximeter. We are now investigating the dependency of the measurements on various physiological conditions and skin characteristics in order to determine appropriate calibration procedures. This study has demonstrated for the first time that arterial hemoglobin oxygen saturation can be measured quantitatively using transcutaneous reflectance techniques. However, more extensive work is needed to further develop this technique into a viable clinical tool.

Humans↗
PubMed1982

Physical and chemical sensors for medical instrumentation.

The sensor represents one of the most important aspects of a biomedical instrument in that it is concerned with the interface between the instrument and the physiologic system being measured. Examples of sensors being developed in our laboratory are presented. These include applications of a miniature silicon piezoresistive pressure transducer to measuring intrauterine and intraurethral pressures; a force sensor for use in neuromuscular control research; an instrument system for the in vivo analysis of the rheology of the uterine cervix; thin film and active biopotential electrodes for neonates; metal-metal oxide pH sensors fabricated by microelectronic techniques and thin and thick film multiple cathode polarographic oxygen sensors. Speculations on areas of future importance for biomedical sensors complete the manuscript.

Electrodes↗
PubMed1981

C. psittaci 6 BC soluble hemagglutinin: factors influencing the red cell receptor sites.

Human blood-group A, B and O erythrocytes did not possess receptor sites for either crude or ether-ethanol extracted chlamydial soluble hemagglutinin. Sensitive chicken erythrocytes were agglutinated to higher titres by ether-ethanol extracted than by crude chlamydial hemagglutinin. Studies indicated that trypsin-, chymotrypsin-, neuramanidase-sensitive receptor sites were not essential for binding of ether-ethanol extracted chlamydial hemagglutinin; neither were beta-glucuronidase- nor periodate-sensitive receptor sites essential. Since soluble chlamydial hemagglutinin consists of components of host cells and that of chlamydiae purification of hemagglutinin from chlamydiae is required in future studies.

ABO Blood-Group System↗