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Biomedical subjects

C Ray

Publications and source records attributed to C Ray.

At least 91 records · Page 5Linked to original sources
PubMed1981

Technical aspects and clinical implications of high frequency jet ventilation with a solenoid valve.

High frequency jet ventilation (HFJV) is an incompletely studied technique of mechanical respiratory support. The authors have built a ventilator based on a solenoid valve, that allows independent selection of respiratory rate and inspiratory/expiratory ratio. The ventilator can be synchronized to the heart rate. Humidification is provided by warm saline dripped in front of the injector nozzle, so that the jet stream itself acts as a nebulizer. Tube diameter, length, and deformability are fundamental determinants of inspiratory flow rate and wave form. Cannula kinking and inadequate humidification were the most significant sources of complications.

Respiration, Artificial↗
PubMed1980

Evaluation of an "in vivo" PaO2 and PaCO2 monitor in the management of respiratory failure.

A commercially available gas-chromatograph (Sentorr Gas Analyzer, Ohio Medical Products, Madison, WI) was tested, featuring continuous measurement of in vivo PaO2 and PaCO2 by means of a thin, heparin-coated catheter, inserted through an indwelling arterial line. Gas tensions are displayed every 4 min. The probes had a tendency to break rather easily, and a considerable proportion of them was faulty. We measured 105 paired determinations of blood gases obtained from patients in respiratory failure requiring mechanical ventilation with a Corning IL 175 Analyzer and displayed by the Sentorr Gas Analyzer. A high correlation (p < 0.01) existed between the two sets of values, but an estimated error of 10-20% was found in the Sentorr data. After modifications of the respirator, changes of displayed values were already notable after 4 min and 90% completed by 8-12 min. The use of this device enabled us to considerably accelerate decision-making in the management of respiratory failure. Although techology still necessitates improvements, before widespread use of in vivo monitoring of PaO2 and PaCO2 is advisable, the concept has significant clinical potential and may represent a major advance in the management of respiratory failure.

Carbon Dioxide↗
PubMed1980

Dental and social effects of malocclusion and effectivenessof orthodontic treatment: a review.

The relationship between malocclusion and the health of the masticatory apparatus is reviewed. While there is evidence that certain features such as traumatic deep overbite, unprotected incisors and impacted teeth may adversely affect the longevity of the dentition, the relationship of dental irregularity to periodontal disease, caries and mandibular dysfunction is less certain. Studies in the field of social psychology indicate that an unattractive physical appearance may evoke an unfavourable social response in many facets of social interaction but the place of dentofacial anomalies in this context has not been satisfactorily assessed. The individual's adjustment to his own imperfections in dental alignment is variable and there is no evidence that children with visible irregulaities will in general be emotionally handicapped. Effectiveness studies have yet to be undertaken but the factors which will have to be taken into account in assessing the benefits of orthodontic treatment are the definition of treatment need, treatment standards, the disadvantages of treatment and the influence of other determinants of dental health. The need for further research is underlined.

Dental Caries↗
PubMed1979

Multiple determination of cardiac output using a two-bottle technique.

A technique is described to perform multiple determinations of cardiac output; two 150 ml bottles of 5% dextrose in water, stored in identical conditions, are immersed in an ice slush, contained in a styrofoam cooler. Comparison of cardiac output determinations obtained with this technique and with multiple syringes indicates very close duplication of results. The technique is very inexpensive and allows one to follow patients for up to four hours with as many as 30 consecutive determinations of cardiac output.

Cardiac Output↗
PubMed1979

Examination stress and performance on a color-word interference test.

Interference observed in the Stroop color-word task is influenced by various characteristics of the words employed. 38 students in their final year, approaching examinations, were asked to name the colors of words associated with this theme. These words produced greater delay than a control set, and those students who were most anxious about the examinations experienced most interference. This effect might be more generally employed in stress research, providing a performance-based index of reaction to issues or situations which are potential sources of anxiety.

Arousal↗
PubMed1978

A study of the interaction of catecholamines and antidiuretic hormone on water permeability and the cyclic AMP system in isolated papillae of the rat.

The diffusional water permeability of collecting ducts in vitro and the cyclic A.M.P. content of isolated papillae were measured after exposure to different concentrations of antidiuretic hormone, isoproterenol and noradrenalin. Antidiuretic hormone 25 mu units/ml. caused a 25% increase in diffusional water permeability. This response was not affected by isoproterenol (10(-6) M) or noradrenalin (2 x 10(-6) M). Antidiuretic hormone 100 mu unit ml-1 caused a 50% increase in diffusional water permeability which likewise was not altered by isoproterenol or noradrenalin. Isoproterenol (10(-6) M) and noradrenalin (2 x 10(-6) M) had no significant effect on basal levels of diffusional water permeability. Isoproterenol had no significant effect on the tissue concentration of cyclic A.M.P. concentration induced by antidiuretic hormone. Noradrenalin (2 x 10(-6) and 10(-4)) had no significant effect on basal cyclic A.M.P. concentration. However, noradrenalin inhibited the stimulation of cyclic A.M.P. induced by antidiuretic hormone. This effect was inhibited by phentolamine. This study suggests that catecholamines do not alter water handling by a direct action on the water permeability of the kidney but probably exert their action through an effect of A.D.H. release.

Animals↗
PubMed1978

Criteria for selective positive end-expiratory pressure and independent synchronized ventilation of each lung.

Respiratory failure of different origins often requires therapy with mechanical ventilation and positive end-expiratory pressure (PEEP). These supports are occasionally inadequate if the damage to one lung is significantly more pronounced than that to the other lung. Technical means exist to ventilate each lung independently or to provide a different PEEP to each lung. The findings from nine patients in whom one of these techniques was applied are presented, and advantages and disadvantages are discussed.

Adult↗
PubMed1977

Psychological implications of mastectomy.

The adjustment of a group of mastectomy patients to their operation was assessed at an interval of between 18 months and 5 years after surgery. They were found to be significantly more depressed and anxious than a control group of cholecystectomy patients; they tended to have lower self-esteem; and they described themselves as being more introverted in their behaviour. These differences were attributed to concern about both the loss of the breast and the possibility of recurrence of the cancer.

Adjustment Disorders↗
PubMed1976

Inhibition of human neutrophil chemotaxis and chemiluminescence by amphotericin B.

The effect of the antifungal drugs amphotericin B, fluocytosine, miconazole, griseofulvin, and nystatin on the chemotactic responsiveness of human neutrophils was studied. Amphotericin B in a concentration of 2 mug/ml inhibited chemotatic responsiveness, and in a concentration of 5 mug/ml it also inhibited chemiluminescence. The inhibition of chemotaxis could be reversed by washing the cells. The other antifungal drugs did not inhibit chemotaxis even in concentrations much higher than those obtained in human serum during treatment.

Amphotericin B↗
PubMed1976

The effect of hemodialysis on neutrophil chemotactic responsiveness.

Fifteen patients with chronic renal failure had depressed neutrophil chemotactic responsiveness following several hemodialysis treatments. The chemotactic index (C.I.) of these patients was 12.7+/-6.4 as compared with 72.8+/-22.7 for controls (p less than 0.001). Patients with chronic renal failure, not on hemodialysis, had only mildly depressed neutrophil chemotactic responsiveness (42.3+/-15;p less than 0.01). Thus, hemodialysis impairs neutrophil function and may contribute to the increased risk of infection in uremic patients. Chemotactic responsiveness returned to normal in three patients following renal transplantation.

Bacterial Infections↗