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Biomedical subjects

M J Decker

Publications and source records attributed to M J Decker.

33 records · Page 2Linked to original sources
PubMed1992

Extended monitoring of oxygen saturation in chronic lung disease.

The goal was to determine values of oxygen saturation from oximetry measurements over extended time periods in the context of prescribing or discontinuing supplemental oxygen. For group 1, when supplemental oxygen therapy was not in use, mean SpO2 values were significantly lower than when it was in use. Without supplemental oxygen, six of eight patients spent greater than 10 percent of the time at or below 88 percent saturation. For group 2, three of the nine patients spent 10 percent of the time at or below 88 percent SpO2. In 16 of 17 patients, lowest room air recorded values of SpO2 were less than 88 percent. We conclude that in many patients with chronic respiratory illness, prolonged monitoring of SpO2 will disclose the presence of hypoxemia. There may be substantial differences in health care cost and outcome depending upon the criteria chosen to prescribe or continue supplemental oxygen.

Adult↗
PubMed1992

The nasal response to exercise in patients with cystic fibrosis.

This study has evaluated the nasal response to exercise in patients with cystic fibrosis (CF), a genetic disease in which factors such as chronic lung disease and/or nasal polyposis might be anticipated to modify nasal function responses. Measurements of nasal resistance (NAR) by posterior rhinomanometry and specific airway resistance (sRAW) were made before and 1, 5, 10, and 30 min after a 4-min period of exhausting legwork exercise (50% predicted maximal) in 19 CF patients (aged 11-29 years) and 10 healthy subjects (aged 11-31 years). One minute after exercise, healthy subjects showed a 54 +/- 5% (mean +/- SEM; standard error of the mean) relative fall from baseline in NAR and CF patients showed a 31 +/- 8% relative fall from baseline (p < 0.05). There were no significant differences in the magnitude or pattern of recovery in NAR after exercise (1 to 30 min) between the groups, largely because of the variability in NAR responses in CF patients. Exercise did not result in significant changes in sRAW in either group. We also found that a history or presence of nasal polyposis does not significantly affect functional nasal responses to exercise. Our conclusion is that the CF genotype and its airway sequelae do not substantively affect the control of the nasal response to exercise.

Adolescent↗
PubMed1990

Assessing the characteristic between length of hypoxic exposure and serum erythropoietin levels.

We examined the relationship between the duration of hypoxic exposure and serum erythropoietin (EPO) production. Adult male Long-Evans rats were exposed to hypobaric hypoxia (HH = 0.5 atm) for a period of 15 min to 20 days. Serum for EPO by radioimmunoassay was collected immediately, 1 or 2 h after HH exposure. A significant rise in EPO levels occurred 1 h after a 30-min HH exposure that was not sustained 2 h after termination. One hour of HH exposure resulted in increased EPO levels 1 h after termination of exposure and further increased levels 2 h after termination of exposure. With prolonged exposure, serum levels remained elevated at 6 and 20 days, despite the development of polycythemia. We concluded that the hypoxic stimulus for elevation of serum EPO could be as short as 30 min and that EPO levels remained elevated after chronic HH. The experimental data were consistent with a mathematical model in which stimulated EPO production was proportional to the time of HH stimulus.

Animals↗
PubMed1990

Agreement between noninvasive oximetric values for oxygen saturation.

We made an assessment of five pulse oximeters in regard to their ability to replace the HP ear oximeter as a noninvasive measurement of SaO2. Trials were performed during isocapnic progressive hypoxia (SaO2 range, 99 to 70 percent) in 22 white and six black subjects. Comparisons between values of SaO2 by oximetry were analyzed by comparing the difference of values by the two methods against their mean. The difference between pulse oximeters and the HP was 2.6 +/- 10.3 percent in all subjects. Results in whites were 1.9 +/- 10.2 percent and in blacks were 5.1 +/- 9.2 percent. The distribution of differences between pulse oximeters and the HP were larger below 80 percent than above 85 percent. We conclude that pulse oximeters give higher values than the HP, a tendency which is more pronounced in black than in white subjects. While the limits of agreement are better at saturations above 85 percent, the 95 percent confidence limits of agreement between pulse oximeters and the HP are rather large (+/- 10 percent) and unacceptable for assuming that pulse oximeters will provide the same values as found in clinical studies using the HP.

Adolescent↗
PubMed1989

Ambulatory monitoring of arterial oxygen saturation.

We have developed a method of recording oxygen saturation over time using ambulatory equipment. A pulse oximeter was modified to be powered by battery, and values for oxygen saturation were recorded by an analog recorder. The unit is compact and functions for 30 hours between battery changes. The mean difference between oxygen saturation reported by the pulse oximeter and an IL 282 CO-oximeter was -1.12 percent, with a range of difference +/- 2.75 percent, indicating 95 percent confidence limits 5.5 percent either side of the mean. Continuous ambulatory recordings were obtained in 16 male subjects; six were healthy nonsnorers, five were healthy snorers, and five had sleep apnea. Of the average recording time, 19 +/- 5 hours, records contained 89 +/- 7 percent usable data. We conclude that ambulatory pulse oximetry is a feasible means of unsupervised long-term monitoring of oxygenation during daily activities.

Humans↗
PubMed1988

The nasal response to exercise and exercise induced bronchoconstriction in normal and asthmatic subjects.

Two studies were carried out to test the hypothesis that the fall and recovery of nasal resistance after exercise in asthmatic and non-asthmatic subjects are related to the development of bronchoconstriction after exercise. In study 1 nasal resistance (posterior rhinomanometry) and specific airway resistance (sRaw) were measured before challenge and one, five, 10 and 30 minutes after four minutes of exhausting legwork exercise in nine asthmatic subjects and nine age matched healthy subjects. One minute after exercise there was a reduction in nasal resistance of 49% (SD 15%) from baseline in the healthy subjects and of 66% (17%) in the asthmatic subjects. This response and the subsequent return of nasal resistance to baseline values did not differ significantly between the two groups despite a substantial difference in the change in sRaw, an increase of 74% (45%) in the asthmatic subjects 10 minutes after exercise, and no change in the non-asthmatic subjects. In study 2, nasal and specific airway resistances were monitored according to the same measurement protocol in six subjects with increased airway reactivity. Subjects exercised on two occasions, wearing a noseclip, once while breathing cold, dry air and once while breathing warm, humid air. The fall in nasal resistance was similar under both conditions (to 47% and 39% of baseline), through sRaw rose only after cold air inhalation (to 172% of baseline). The results indicate that the nasal response to exercise is not related to bronchial obstruction in asthmatic subjects after exercise or to the temperature or humidity of the air inspired through the mouth during exercise.

Adult↗
PubMed1982

Performance of a new rate-nephelometric assay for rheumatoid factor, and its correlation with tube-titer results for human sera and synovial fluid.

We evaluated a rate-nephelometric assay for rheumatoid factor (RF), as developed for use with the Beckman Immunochemistry System (ICS). Within- run precision (CV) for low-, mid-, and high-dilution samples (60-400 kilo-int. units/L) was 3.5, 1.5, and 1.6%; between-run precision was 3.4%. Analytical linearity was excellent. Biological interference resulted in some degree of nonlinearity in more than 70% of the patients' samples tested. Sensitivities were 96.5 and 94.1% and specificities were 98.5 and 95.3% for the ICS RF and Wampole slide methods, respectively, for a clinically defined population of 170 patients. Results for 100 ICS RF-positive samples correlated well with concomitantly measured Calbiochem-Behring tube-titers. Weekly measurement of Calbiochem-Behring. Hyland Diagnostics, and ICL Scientific tube-titer values for RF along with the ICS RF values on samples from the same patients indicated stable ICS RF values but showed at least +/- 1 tube dilution variances both within and between the tube-titer methods. Therefore, it may not be appropriate to compare a precise new method with a relatively imprecise comparison method. Treatment of RF-positive samples with dithiothreitol, which disrupts the pentameric character of immunoglobulin M, rendered the samples negative by repeat ICS RF assay and confirmed the method's specificity for pentameric immunoglobulin M-RF. Serum RF concentration as determined by ICS paralleled changes in clinical symptoms in a patient treated with both effective and relatively ineffective regimens, which suggests a useful role for the assay in monitoring efficacy of clinical treatment.

Agglutination Tests↗
PubMedDate not supplied

Blood pressure variation among Ethiopians on the Simien Plateau.

This report presents information on determinants of blood pressure variation in a rural sample of 263 Ethiopian highlanders 14-86 years of age, resident at 3530 m on the Simien Plateau. Mean systolic and diastolic blood pressures for males and females were 109/ 75 and 106/73, respectively, and there were no age differences. These findings confirmed that men and women can have low normal blood pressure throughout adulthood. Blood pressures increased with increasing body mass index (BMI) among adult males, although the mean BMI of 19.1 kg/m2 was low compared with US values. This illustrates that BMI variation may be associated with blood pressure variation in men even at low mean values of both. Blood pressure did not vary with adult haemoglobin concentration.

Adolescent↗
PubMedDate not supplied

Serratus anterior muscle activity during selected rehabilitation exercises.

The purpose of this study was to document the electromyographic activity and applied resistance associated with eight scapulohumeral exercises performed below shoulder height. We used this information to design a continuum of serratus anterior muscle exercises for progressive rehabilitation or training. Five muscles in 20 healthy subjects were studied with surface electrodes for the following exercises: shoulder extension, forward punch, serratus anterior punch, dynamic hug, scaption (with external rotation), press-up, push-up plus, and knee push-up plus. Electromyographic data were collected from the middle serratus anterior, upper and middle trapezius, and anterior and posterior deltoid muscles. Each exercise was partitioned into phases of increasing and decreasing force and analyzed for average and peak electromyographic amplitude. Resistance was provided by body weight, an elastic cord, or dumbbells. The serratus anterior punch, scaption, dynamic hug, knee push-up plus, and push-up plus exercises consistently elicited serratus anterior muscle activity greater than 20% maximal voluntary contraction. The exercises that maintained an upwardly rotated scapula while accentuating scapular protraction, such as the push-up plus and the newly designed dynamic hug, elicited the greatest electromyographic activity from the serratus anterior muscle.

Adult↗
PubMedDate not supplied

A comparison of a new reflectance oximeter with the Hewlett-Packard ear oximeter.

The purpose of this study was to characterize the accuracy and dynamic response characteristics of traditional transmittance pulse oximeters and a new reflectance pulse oximeter with regard to the current standard in oximetry, the Hewlett-Packard ear oximeter. Studies were performed with 15 healthy male and female subjects. A rebreathing technique was employed to produce a steady fall in oxygen saturation and to maintain constant, eucapnic, end-tidal CO2 levels. The oximeters' analog outputs were recorded by a Western Graphtec Linearecorder and by an IBM-PC utilizing an analog-to-digital converter for data collection at 5 Hz. The agreement between two clinical methods of measurement was used as the statistical technique of comparing new technology (pulse oximetry) with the current standard (Hewlett-Packard ear oximetry). The mean of the difference between the Hewlett-Packard and the pulse oximeter with reflectance sensor was 0.28%, with a range of difference of +/- 3.49%. This value was similar to that of the transmittance oximeters (Criticare 501+: 0.92 +/- 2.11), (Physio-Control: 3.15 +/- 2.04), (Ohmeda 3700: 2.05 +/- 2.06). There was virtually no response-time difference between the reflectance oximeter with the sensor placed on the subject's forehead and the Hewlett-Packard ear oximeter. The authors conclude that the accuracy of the reflectance oximeter is within the limits of clinical acceptance for monitoring and trending of arterial oxygen saturation in healthy subjects.

Equipment Design↗
PubMedDate not supplied

Noninvasive oximetry in the rat.

To aid in the development of rodent models of respiratory dysfunction, the authors evaluated the ability of noninvasive pulse oximetry (SpO2) to continuously monitor oxygen saturation (SaO2) in the rat. In initial studies, a pulse oxyimeter (Nellcor N-100) detected a fall in SaO2 during hypoxia induced by hypobaric decompression or decreasing fractions of inspired oxygen (FIO2). The disposable sensor was placed proximally on the tail. To assess the accuracy of pulse oximetry, arterial blood samples (86 samples from 25 animals) were obtained via a femoral arterial catheter while the FIO2 was varied between 0.08 and 0.40. The blood samples were analyzed with an IL 282 CO-Oximeter for SaO2 and then compared with pulse oximeter values of SaO2. Between saturations of 75% and 95%, the standard deviation (SD) for the difference between the CO-Oximeter and pulse oximeter measurements of SaO2 was +/-5.7%; however, below 70%, mean pulse oximeter estimates were higher than arterial values and the SD for the difference increased. It is concluded that pulse oximetry can detect trends in oxygenation over time in anesthetized and unanesthetized rats and that the accuracy of pulse oximetry is such that between 75% and 95% SaO2 agreement between pulse oximetry and arterial blood sample values of SaO2 is acceptable.

Animals↗
PubMedDate not supplied

Effect of long-term angiotensin-converting enzyme inhibitor therapy on arterial oxygen saturation in patients with mild to moderate heart failure.

STUDY OBJECTIVE: To evaluate the effects of angiotensin-converting enzyme (ACE) inhibition on continuous pulse oximetry recordings of arterial oxygen saturation (SpO2). DESIGN: Open-label study. SETTING: Cardiology clinics at two large teaching hospitals. PATIENTS: Eight patients with New York Heart Association Functional Class (NYHA FC) II-III heart failure. INTERVENTIONS: Patients were studied after an ACE inhibitor washout (baseline, B), and after 3 months following resumption of therapy (ACE). MEASUREMENTS AND MAIN RESULTS: Monitoring times for B and ACEI were approximately 22 hours. Reduction trends were observed for number (190 +/- 170 vs 125 +/- 67 B vs ACEI), magnitude (8.2 +/- 1.4% vs 7.5 +/- 1.8%), and duration (2.45 +/- 2.8 vs 1.35 +/- 0.8 min) of desaturations/monitoring period, and for nadir SpO2/desaturation (88.1 +/- 1.5% vs 89.9 +/- 3.3%). The B desaturation index [(cumulative desaturation time/monitoring period time) x 100, a measure of hypoxic stress or burden] decreased from 19.4 +/- 8.1% to 11.9 +/- 8.1% at ACEI (p = 0.024). CONCLUSION: Long-term ACE inhibitor therapy improves the profile of SpO2 values over time in patients with NYHA FC II-III heart failure.

Adolescent↗