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Biomedical subjects

M R Neuman

Publications and source records attributed to M R Neuman.

At least 19 recordsLinked to original sources
PubMed1997

Infant polysomnography: reliability. Collaborative Home Infant Monitoring Evaluation (CHIME) Steering Committee.

Infant polysomnography (IPSG) is an increasingly important procedure for studying infants with sleep and breathing disorders. Since analyses of these IPSG data are subjective, an equally important issue is the reliability or strength of agreement among scorers (especially among experienced clinicians) of sleep parameters (SP) and sleep states (SS). One basic issue of this problem was examined by proposing and testing the hypothesis that infant SP and SS ratings can be reliably scored at substantial levels of agreement, that is, kappa (kappa) > or = 0.61. In light of the importance of IPSG reliability in the collaborative home infant monitoring evaluation (CHIME) study, a reliability training and evaluation process was developed and implemented. The bases for training on SP and SS scoring were CHIME criteria that were modifications and supplements to Anders, Emde, and Parmelee (10). The kappa statistic was adopted as the method for evaluating reliability between and among scorers. Scorers were three experienced investigators and four trainees. Inter- and intrarater reliabilities for SP codes and SSs were calculated for 408 randomly selected 30-second epochs of nocturnal IPSG recorded at five CHIME clinical sites from healthy full term (n = 5), preterm (n = 4), apnea of infancy (n = 2), and siblings of the sudden infant death syndrome (SIDS) (n = 4) enrolled subjects. Infant PSG data set 1 was scored by both experienced investigators and trained scorers and was used to assess initial interrater reliability. Infant PSG data set 2 was scored twice by the trained scorers and was used to reassess inter-rater reliability and to assess intrarater reliability. The kappa s for SS ranged from 0.45 to 0.58 for data set 1 and represented a moderate level of agreement. Therefore, rater disagreements were reviewed, and the scoring criteria were modified to clarify ambiguities. The kappa s and confidence intervals (CIs) computed for data set 2 yielded substantial inter-rater and intrarater agreements for the four trained scorers; for SS, the kappa = 0.68 and for SP the kappa s ranged from 0.62 to 0.76. Acceptance of the hypothesis supports the conclusion that the IPSG is a reliable source of clinical and research data when supported by significant kappa s and CIs. Reliability can be maximized with strictly detailed scoring guidelines and training.

Humans↗
PubMed1994

Ion-selective membranes with low plasticizer content: electroanalytical characterization and biocompatibility studies.

High molecular weight poly(vinyl chloride) and aliphatic polyurethane (Tecoflex)-based ion selective membranes, with normal and reduced amounts of plasticizer, as well as without plasticizer, were tested with respect to their analytical properties, their biocompatibility, and cellular responses. The analytical properties of the membranes did not change significantly within a wide range of polymer to plasticizer ratios. However, the membranes with reduced plasticizer content had better adhesive properties, less anion interference, extended life time, and better biocompatibility. Using the cage implant system, the results showed that an increase of plasticizer weight percent in Tecoflex membranes correlated positively with the increase in host inflammatory response up to 14 days of implantation. The results also demonstrated that both PVC and Tecoflex-based ion-selective membranes with the most common membrane composition (1:2 polymer to plasticizer ratio) exhibited a similar acute inflammatory response, but the PVC-based membrane elicited a reduced chronic inflammatory response when compared with the Tecoflex-based membrane.

Adhesiveness↗
PubMed1994

Electroanalytical and biocompatibility studies on carboxylated poly(vinyl chloride) membranes for microfabricated array sensors.

Potassium ion-selective and pH membrane electrodes based on neutral carrier ionophores for K+ (valinomycin) and H+ (TDDA and ETH 5294), respectively, immobilized in carboxylated PVC (PVC-COOH) with normal (classical) and reduced amounts of plasticizer, were investigated with respect to their general analytical performances (linear range, slope, detection limit, selectivity, internal membrane resistance), their biocompatibility and cellular responses. The analytical performance of potassium selective electrodes was not affected by reducing the plasticizer content from 66% (m/m) to about 33% (m/m) while that of pH electrodes was significantly changed at the lower plasticizer concentration level. The adhesive properties of PVC-COOH membranes to an inert substrate such as polyimide-coated Kapton are greatly improved by reducing the plasticizer content of the membrane. In addition, as was reported earlier by this group, improved biocompatibility was observed with these membranes relative to those with increased plasticizer content. A ratio of 1:1 m/m for PVC-COOH to plasticizer is recommended for the construction of planar ISEs without massive use of internal solution.

Animals↗
PubMed1992

Optimal electrode location for monitoring the ECG and breathing in neonates.

Continuous monitoring of breathing in infants is commonly performed using transthoracic impedance. This method employs skin surface electrodes measuring changes in electrical impedance and relates these changes to respiratory events. Typically, two electrodes on the infant's chest monitor both the ECG and breathing. We have attempted to identify separate electrode locations that give the best signal for breathing and ECG, and a single location that optimizes both of these signals. Thirty-seven infants were studied by placing 12 electrodes on the infant's chest and abdomen, and serially sampling pairwise combinations of electrodes. The optimal signal for breathing was obtained when electrodes spanned the diaphragm. Optimal ECG signal was seen with one electrode at the right mid-clavicle and one at the xyphoid. Clinicians should be aware of these locations in order to provide the best signal available.

Abdomen↗
PubMed1992

Response of fetal heart rate to scalp stimulation related to fetal acid-base status.

The correlation of the response of the fetal heart rate (FHR) to scalp stimulation and the acid-base status of the fetal scalp blood (FSB pH) was studied in 104 term fetuses during labor. The mean FHR was determined for the 5-minute period before the preparation for fetal scalp blood pH determination and 1 minute following FSB pH. The analysis was performed for three pH groups: (a) Normal (pH more than 7.25, = 73); (2) preacidotic (pH 7.20 to 7.25, = 16); and (3) acidotic (pH less than 7.20, = 15). The pH was confirmed at delivery by determination of umbilical cord blood acid-base status. Regression analysis of the number of fetuses responding by changing their heart rate against time was significant only for the nonacidotic fetuses. There was no significant difference in the number of subjects whose mean FHR increased, decreased, or remained unchanged between the three pH groups. Furthermore, there was no difference between the three pH groups in the number of fetuses who demonstrated significant mean heart rate changes (p less than 0.05) following the stimulation compared to those who did not. Further analysis between fetuses in the three pH groups who increased FHR 15 beats/min or more following stimulation did not discriminate between groups. We conclude that scalp stimulation results in a FHR response in all three pH categories. However, the net change in the mean heart rate following the stimulation may be negative or positive. The magnitude and the direction of this change in FHR is not significantly related to FSB pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1991

Effect of infant position on breath amplitude measured by transthoracic impedance and strain gauges.

Continuous monitoring of respiration by transthoracic electrical impedance gives a signal that has certain not well understood irregularities. Among them is a change in the amplitude of the signal when there is no apparent change in the infant's tidal respiration. One factor that could hypothetically account for alterations of the impedance signal is a change in current path through the thorax secondary to a change in body position. To test this hypothesis we have studied the relationships between breath amplitude measured by transthoracic impedance, one strain gauge on the chest and one on the abdomen, and tidal volume by integrated flow in four body positions. Median breath amplitude was found to vary significantly with body position according to the measuring device. The median impedance breath amplitude increased by 27% in the supine position compared with the prone position, with no associated change in tidal volume. Differences in the strain gauge signal amplitude for these positions were not statistically significant. Correlation between breath amplitude measured by impedance changes and tidal volume was minimal (r = 0.114). These results indicate that infant position affects impedance breath amplitude independently of changes in tidal volume.

Cardiography, Impedance↗
PubMed1990

Direct quantitation of skin elasticity in systemic sclerosis.

A simple instrument, the "skin elastometer," was used to evaluate the elastic and plastic properties of volar forearm skin in 24 patients with systemic sclerosis and 24 healthy individuals matched for age, race and sex. Skin elastance in 17 patients with diffuse scleroderma was found to be significantly different from matched controls (p less than 0.001), and was associated with clinical skin scores independently determined by examination (r = 0.89, p less than 0.001). Seven patients with limited scleroderma (the CREST variant) had values for skin elastance which were intermediate between those of the patients with diffuse scleroderma and healthy persons. Plastic deformation of the stretched skin was similar in patients and controls. Quantitative measurement of skin elastance is a simple technique which may prove to be of value in the assessment of patients with systemic sclerosis.

Adult↗
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↗