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Biomedical subjects

C J Martin

Publications and source records attributed to C J Martin.

At least 145 records · Page 8Linked to original sources
PubMed1981

The use of infrared radiation to reduce heat loss in burned patients: experiments with a phantom.

Heat losses from patients with severe burns place considerable demands on the body. The metabolic rate, already elevated as a result of the injury, must rise further to maintain thermal equilibrium. To compare different methods of supplying heat to burned patients, a phantom has been constructed in which a free water surface has been used to simulate burned tissue. The effect of environmental temperature, humidity and air velocity, and of radiant energy, on the evaporation rate from the water surface, and on the energy supplied to the water to maintain its temperature, have been measured. Results showed that humidity and air velocity were the main factors determining evaporation. The internal energy required to maintain the temperature of the phantoms could be reduced by use of infrared radiation. This is particularly appropriate in the clinical situation, as energy is supplied to the skin surface, where it can replace directly energy lost through evaporation. Because the effect of radiant energy on the evaporation rate was small, it may be possible to create a microclimate around a patient where air velocity can be set to give a desired rate of evaporation, and the infrared level can be adjusted for patient comfort.

Body Temperature Regulation↗
PubMed1981

Standardized interviews in psychiatry: issues of reliability.

A review of studies which used standardized interviews as a means of data collection indicated that the issue of reliability was frequently neglected in the psychiatric literature. It is suggested that this may be due to a misinterpretation of the concept of reliability which is apparently perceived as a permanent feature of an interview instrument. The importance of reliability is discussed, and recommendations are made as to how a methodologically adequate assessment of reliability might be undertaken.

Humans↗
PubMed1981

Peritoneoscopy--use in assessment of intra-abdominal malignancy.

Peritoneoscopy was performed on 236 patients between 1971 and 1980 to assess intraabdominal malignancy or to determine its presence when doubt existed. The diagnostic rate was 86%. The main causes of failure to reach a diagnosis were adhesions arising from previous surgery and tumor adhesions. It was a useful means of obtaining a tissue diagnosis, and the complication rate was low--4.5%. Peritoneoscopy demonstrated the cause of hepatomegaly in 90.9% of patients, the pathology of abdominal masses in 82.5%, and of ascites in 80.5%. It was also useful in assessing abdominal ultrasound and isotope liver scan abnormalities. The procedure is safe, cheap, and allows adequate assessment of intra-abdominal malignancy in a high proportion of patients.

Abdominal Neoplasms↗
PubMed1980

The use of thermistor probes to measure energy distribution in ultrasound fields.

The use of small thermistors coated with absorbing material for the measurement of ultrasound fields is discussed. Equilibrium temperature rise gives a rough measure of intensity, but is affected by convective cooling due to streaming. The initial rate of temperature rise provides an accurate parameter for use in assessing energy density in all types of ultrasound field. Measurements made in standing wave fields show that the thermistor response is related to the pressure component of the sound wave, and is determined by absorption throughout the coating material.

Energy Transfer↗
PubMed1980

High-performance liquid chromatographic determination of metaraminol bitartrate in the presence of parabens.

A high-performance liquid chromatographic (HPLC) procedure was developed for the determination of metaraminol bitartrate in the presence of methylparaben and propylparaben. Reversed-phase ion-pair chromatography was employed using dioctyl sodium sulfosuccinate as the counterion. The current official USP procedure for the determination of metaraminol requires dilution, extraction, and measurement of UV absorption. The HPLC procedure is rapid and precise and correlates well with the USP XX procedure. It can be used for metaraminol injectables as well as the raw material.

Chromatography, High Pressure Liquid↗
PubMed1979

Characteristics of the washout dead space.

The dead space volume was reproducibly measured in normal and diseased lungs by analysis of an inert gas washout. This washout dead space was appreciably larger than that measured by the Fowler technique. In the patients, the washout dead space (VD(0)) formed 72% of the physiological dead space volume, while the Fowler (VD(F)) method accounted for only 50%. The VD(O) increased significantly with age in males, but not in females. VD(F) was not well related to age in this population. VD(O) and VD(F) did not relate to lung volume in these subjects. Although that portion of the dead space delivered in Phase I was significantly greater in males than in females, it was not responsible for the difference in dead space measured by the two techniques. This volume difference was found in that portion delivered late in the breath (Phase III). The nature of this volume is speculative, but may involve a parallel dead space that is measured in addition to the series dead space.

Adult↗
PubMed1979

A study of ultrasonically induced pulsations of gas-filled channels in Elodea.

The ultrasonically stimulated pulsation of pockets of in elodea has been studied using optical microscopy. The intensity dependence of the microstreaming associated with these pulsations has been measured by observing the rotation of chloroplasts and other organelles in the microstreaming vortices. The threshold energy density to produce microstreaming in a standing wave field was found to be 0 . 03 J m-3 at 700 kHz, equivalent to an average intensity of 5 mW cm-2 in the standing wave field, and 0 . 01 J m-3 at 3 MHz, equivalent to an intensity of 15 mW cm-2. The channels had resonant frequencies in the low megahertz range and the relationship between the channel diameter and the resonant frequency was found to be similar to that for a gas bubble in a liquid.

Chloroplasts↗
PubMed1979

Measurements of the dead space volume.

The "anatomical" dead space is commonly measured by sampling an inert gas (N2) and volume in the exhalation following a large breath of oxygen (VD(F)). It may also be measured from an inert gas washout (VD(O)) that describes both volume and the delivery of VD(O) throughout the expiration. VD(O) is known to increase with age and is enlarged in some obstructive syndromes. VD(O) was appreciably larger than VD(F) in our normal subjects. Both measures increased with lung volume, the increase being entirely due to an increase in the volume of phase I. Physiological dead space (VD(p)) however, did not change significantly with lung volume, showing "alveolar" dead space to diminish as a result. An increase in VD(O) occurred with increasing respiratory frequency that was explained by the increase in volume of phase I. Although an increase in VD(F) occurred with frequency, this was significantly less than that seen by VD(O), i.e., VD(F) did not see the progressive increase in phase I volume with frequency. No lung volume or frequency changes, parasympatholytic or sympathomimetic drugs, or altered patterns of breathing simulated the late delivery of dead space seen in age and some obstructive syndromes.

Aging↗
PubMed1977

A comparative study of the mechanical properties in aging alveolar wall.

Alveolar wall from the lung of aging humans shows a progressive decrease in maximal extensibility, which should follow an increase in resting tissue length rather than a reduction in maximal length. An increase in resting tissue length is compatible with the change in lung volumes and reduction in elastic recoil that occurs with time. A model of the lung was used to compare the effects of a change in resting tissue length in diminishing elastic recoil with that of a reduction in the volume density of the elastic elements (emphysema). Such differentiation is important in selecting an animal that may model the aging or emphysematous lung. In the rat, rabbit, and horse, alveolar walls show no decrease in maximal extensibility with age. In the male monkey (M. nemestrina and M. mulatta) between birth and 2.4 years there is a decrease in maximal extensibility that lacks significance for the limited age span examined. On the other hand, the energy loss in length-tension cycling (hysteresis) of alveolar wall increases in aging humans, diminishes in rats and rabbits, and shows little change in horses and monkeys. The breaking force of alveolar wall increases with age in rats and rabbits but does not change significantly in the other species. Of these species, the monkey promises a better model of the age-related changes in maximal extensibility of alveolar wall. A measure of maximal extensibility can distinguish the effects of dilatation of air spaces from those of destruction of alveolar wall in causing loss of lung elastic recoil.

Adolescent↗
PubMed1976

Terminal nitrogen rise.

Eighteen-breath nitrogen washouts were performed on eight subjects. Each washout could be simulated by a four-compartment model, each compartment with a different ventilation-to-volume ratio and a variable contribution to expiratory flow. In large breaths initiated near residual volume, a terminal nitrogen rise (TNR) was seen. To account for the TNR with this model, there were relatively small changes in flow from compartments with markedly different nitrogen concentration. Reasons are given for believing these compartments could not be the upper and lower lung. Three of these subjects were studied in the supine, seated, and head-down positions. The TNR was seen at the same lung volume in all positions. At routine bronchospirometry in a second group of subjects, sampling with small catheters during a nitrogen washout showed a TNR in the expirate of lungs, lobes, segments, and subsegments in the upright and supine positions. Apparently a large vertical hydrostatic gradient is unnecessary to produce a TNR. Finally, the TNR was shown to occur at that lung volume where transpulmonary pressure is very small and changing rapidly with volume. This TNR was often followed by a terminal nitrogen fall while the lung was continuing to empty. The TNR occurs when flow from a large poorly ventilated compartment increases relative to the flow from other compartments. A model of lung in which the poorly ventilated compartment develops high specific compliance at low lung volume explains these data.

Adult↗
PubMed1976

Chest physiotherapy and the distribution of ventilation.

The injured or postoperative thorax is commonly treated with physiotherapy employing "unilateral breathing" techniques. The ability of these methods to alter the distribution of ventilation and blood flow (oxygen uptake) was examined in four patients undergoing bronchospirometry. No change was observed in these measurements in the lung toward which efforts were being directed to either enhance or restrict the mechanics of breathing. To further examine the problem, two susceptible subjects were hypnotized following intubation for bronchospirometry, and emotional and physical states were suggested that limit motion in one hemithorax. This included the presence of pleuritic pain in one subject who had ample experience with this symptom. In no instance did we find a change in the distribution of ventilation or blood flow to the lung that was supposed to be limited; however, in 17 subjects, lying on one side produced a significant increase in ventilation and blood flow in the dependent lung. Lying on one side or the other consistently and predictably modified ventilation and blood flow, while attempts to produce similar changes by voluntary intention or commonly applied mechanical aids were ineffective.

Breathing Exercises↗
PubMed1976

A test of the practical value of estimating breath sound intensity. Breath sounds related to measured ventilatory function.

Each of four examiners performed standardized physical examinations on a group of patients who had just undergone tests of ventilatory function. The intensity of breath sounds heard with deep inspiration was graded on a rating scale of 0 to 4; the grades in six areas of the chest were added to give a total score, with possible values ranging from 0 to 24. Correlation of breath-sound scores with percentage of predicted forced expiratory volume in one second (FEV1) was significant at the 1 percent level for all of the examiners. Differences between the examiners in their assessment of breath sounds were not statistically significant. Grading the loudness of breath sounds was a poor screening test for mild ventilatory abnormality, but normal breath sounds nearly excluded the possibility of severe reduction in the FEV1. Definitely reduced breath-sound intensity was strong evidence for the presence of obstructive pulmonary disease.

Adult↗
PubMed1975

Simulation of lung tissue properties in age and irreversible obstructive syndromes using an aldehyde.

Weak solutions of CHOH alter tissue properties, probably by forming intermolecular cross-linkages. The maximum length (Lmax) to which alveolar wall can be extended is reduced. If exposed to CHOH while extended, the resting length (LO) of alveolar wall increases. Maximum extensibility (Lambdamax equal to Lmax/LO) decreases. Similar changes are found in the alveolar wall of man with aging and are significantly more marked in patients with irreversible obstructive pulmonary syndromes. A reduction in the energy loss of the length-tension cycle (hysteresis) was seen after exposure to CHOH, however, that does not occur with age or in obstructive syndromes. Because an exposure of alveolar wall to elastase increases LO and hysteresis, we used a staged exposure to CHOH followed by elastase. Tissue suitably prepared by exposure to CHOH followed by elastolysis better simulates the tissue changes of age and irreversible obstructive syndromes.

Aging↗