PubMed Health⌕ Search

Biomedical subjects

C Ray

Publications and source records attributed to C Ray.

At least 73 records · Page 4Linked to original sources
PubMed1982

High-frequency jet ventilation: theoretical considerations and clinical observations.

High-frequency jet ventilation (HFJV) described a technique of mechanical respiratory support based on the delivery of gases under conditions of constant flow and low pressure. Among the benefits ascribed to HFJV are lessened interference with hemodynamic function and reduced danger of barotrauma. The theoretical and technical aspects of HFJV are discussed and the clinical experience with 39 patients in respiratory failure reported. Synchronization of HFMV with heart rate was attempted in three patients. Cardiac output and ejection fraction increased in all of them. At present, results suggest that HFJV may be the ideal form of support for patients with major airway disruption. The available data also indicated that extensive clinical trials are warranted to define advantages and limits of this form of ventilation.

Bronchial Fistula↗
PubMed1981

The effect of prostaglandin E2 and ADH on diffusional water permeability in collecting duct of an isolated rat papilla.

The effect of prostaglandin on diffusional water permeability has been studied in collecting ducts in an isolated rat papilla. PGE2 increased water permeability. The effect was significant at a concentration of 10(-8) mol 1(-1) and was maximal with a concentration of 10(-6) mol 1(-1). The maximal increment of 0.94 +/- 0.10 (SEM) micron s-1 was approximately half that produced by maximal stimulation with antidiuretic hormone (2.18 +/- 0.12 micron s-1). A concentration of 10(-8) mol 1(-1) produced an increase in basal water permeability and 24 mu unit ml-1 ADH, which without PGE2 present gave a similar increase, had no incremental effect. ADH 100 mu unit ml-1 increased permeability to a value similar to that observed in the absence of PGE2. Thus PGE2 and ADH both increase water permeability but the increments are not additive. Indomethacin in a concentration that inhibited prostaglandin production altered the response of the collecting duct to ADH. The dose response curve was shifted to the left and the maximal increase in water permeability and the lowest dose at which a response occurred took place at concentrations less than 1/2 those required in its absence. Prostaglandins influence the action of ADH and it is likely that in life they regulate and modulate the change in water permeability induced by anti-diuretic hormone.

Animals↗
PubMed1981

Anatomical dead space and airway resistance after glycopyrrolate or atropine premedication.

The effects of atropine and glycopyrrolate on anatomical dead space, one and three second forced expiratory volume, maximal expiratory flow rate, and total forced expiratory volume were determined in ten healthy volunteers. Using Fowler's single breath nitrogen analyzing technique, atropine was found to increase dead space by 19.2 per cent at one hour, declining to 11.02 per cent at four hours. Glycopyrrolate increased dead space by 21.57 per cent at one hour, 29.28 per cent at two hours, and 26.65 per cent at four hours. When compared to the effects of saline control injection, the dead space increases are significant. The difference between glycopyrrolate and atropine is significant only at four hours. Increases in maximal expiratory flow rate induced by atropine and glycopyrrolate were significant at one-half hour, while atropine alone induced a significant increase in one second forced expiratory volume. Three second forced expiratory volume and total forced expiratory volume were not significantly altered.

Adult↗
PubMed1981

Stress arousal and coping with surgery.

There is little evidence of a curvilinear relationship between pre-operative emotionality and post-operative adjustment, as predicted by a model which supposes that moderate preoperative anxiety assists adjustment. This paper suggests that the negative affect, or stress, associated with the work of worry should be distinguished from the active coping orientation which it also implies. In this study stress and arousal were assessed pre-operatively in a sample of cholecystectomy patients, and correlations between these scores and various indices of post-operative adjustment were computed. Stress before surgery was positively related to stress and pain experienced post-operatively. Arousal, by contrast, was negatively related to pain, medications and period before discharge. Female patients had higher stress scores than the males, while the direction of the difference was reversed in te case of arousal. These findings are interpreted as support for the significance of the role of coping orientation, as represented by arousal, in promoting adjustment, with emotionality or stress playing a less significant and even negative role.

Adaptation, Psychological↗
PubMed1981

Clinical experience with high frequency jet ventilation.

High frequency jet ventilation (HFJV) has been used in recent years in some forms of respiratory failure, where the presence of barotrauma limited the application of high peak inspiratory pressure. In the present report, the authors describe the clinical experience with 17 patients, who could not be supported with conventional mechanical support and were placed on HFJV. Rates of 100 breath/min, inspiratory/expiratory ratio of 1:2 and cannula size of 1.06--1.62 mm (18--14) gauge were used. Driving pressure required to maintain a PaCO2 of 40--45 torr was 14--45 psig; however, except in 2 patients who developed hemorrhagic tracheitis with subtotal obstruction of both mainstem bronchi, a driving pressure higher than 27 psig was never required, even when PEEP up to 32 cm H2O was used. Of 17 patients treated, 8 survived. In all cases, alveolar ventilation could be maintained within the desired range with high frequency ventilation, even in those patients who eventually died; mechanical support never provided better oxygenation or alveolar ventilation than high frequency ventilation. Hemodynamic function was essentially unchanged with high frequency ventilation; indeed, in three cases, inotropic support with dopamine could be discontinued after initiation of high frequency ventilation.

Carbon Dioxide↗
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↗