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Biomedical subjects

L W Raymond

Publications and source records attributed to L W Raymond.

At least 19 recordsLinked to original sources
PubMed1995

Pulmonary barotrauma and related events in divers.

Although pulmonary barotrauma (PBT) is a well-known clinical entity, its recognition in divers is sometimes delayed and its implications for future diving often are unappreciated. The pulmonary complications of diving activities range from mere discomfort from mediastinal emphysema or pneumothorax, or both, to life-threatening gas embolization. In nine cases described here, only minor manifestations were associated with PBT which occurred at or close to the surface, but three of these four divers were found to have abnormal pulmonary function. More serious manifestations resulted from PBT which took place at depths of 16 to 120 ft. Even minor forms of PBT should be considered a contraindication to further diving, since they are prone to recur. Such recurrences--even at shallow depths--may cause serious complications.

Adolescent↗
PubMed1980

Is the weight loss of hyperbaric habitation a disorder of osmoregulation?

To examine the weight loss of hyperbaric helium-oxygen habitation, we measured the exchange of liquids and calories in six men who lived in this atmosphere for 32 d. The maximum pressure was 49.5 ATA. The men lost 3.7-10.1 kg, in spite of warm ambient (31-32 degrees C) temperatures and adequate calories (2,737 kcal/d) provided for the sedentary ways of chamber living. Weight loss and a calculated fluid deficit were accompanied by significant hemoconcentration, shown by increases in serum proteins. These changes were followed by a rise in urinary aldosterone and vasopressin, but not thirst. Weight loss in hyperbaric atmospheres is probably multifactorial, but our data suggests an uncoupling of normal osmoregulation may have occurred in the present set of subjects. This may have been due to altered lung mechanics, increased catecholamines, or effects of high pressure on cellular responses to vasopressin.

Aldosterone↗
PubMed1980

Scars without wounds: spectrum of delayed manifestations of histoplasmosis outside of the endemic area.

This short series represents a spectrum of histoplasmosis usually described only in places where the infection is nearly universal. In fact, most of the patients in this series were born in such places (17 of 19 patients with complicated presentations; 2 had recent suspicious exposures). As young adults, they had moved away to pursue military life, usually in coastal areas where the evidence of infection with H. capsulatum is a statistical rarity. The implications of these observations are straightforward. At the clinical level, they focus on histoplasmosis as a possible cause of pulmonary, mediastinal, or other lesions of obscure etiology, whether or not the patient has recently lived in "the endemic area". The simple determination of CF gamma titers may heighten the index of suspicion, especially when not confounded by skin testing with histoplasmin, a practice which rarely provides useful information. [Table: see text] With regard to pathogenesis, it seems noteworthy that common form of histoplasmosis was not seen in this brief experience. That is the "marching cavity" described by Goodwin and Des Prez, and other forms of chronic cavitary disease. The absence of such lesions is consonant with the view that they require continuous exogenous infection for their development. As for the forms of histoplasmosis which were seen in this series, it appears that most of the illnesses developed outside of what is usually considered endemic areas. The term endemic, as construed medically, has been defined as "restricted to and constantly present in a particular country or locality". Such a construction is unduly pedantic and rigid for clinicians. A more probabilistic view is needed, with attention to the possible role of inapparent infection early in life and of environmental foci of infection in places where the organism is not notoriously present. The mobile nature of our society makes it likely that the radiographic manifestations of once-regional diseases such as this one will be encountered more generally than in the past.

Adolescent↗
PubMed1979

Pulmonary toxicity of bischloronitrosourea: report of a case with transient response to corticosteroid therapy.

A case of interstitial pulmonary fibrosis secondary to bischloronitrosourea (BCNU) in a 49-year-old man with carcinoma of the pancreas is reported. The diagnosis was suggested by deteriorating oxygenation, restrictive changes on pulmonary function studies, and increased interstitial markings radiographically in the lower lung fields. Transbronchial biopsy excluded infectious etiologies and confirmed a bland nonspecific interstitial pulmonary fibrosis of recent origin. The patient responded dramatically to high dose corticosteroids, but relapsed when the corticosteroids were decreased. We believe there is now convincing evidence that prolonged use of BCNU can cause potentially fatal interstitial pulmonary fibrosis. Patients should be followed with serial chest radiographs and pulmonary function studies. If diagnosed early, this process may respond to high dose corticosteroid therapy.

Carmustine↗
PubMed1978

The alveolar air equation abbreviated.

The alveolar air equation is not widely used in clinical medicine, probably because of the complicated appearance of its classic forms. The following shorter form has been derived: formula: see text (where PAO2, PEO2, and PIO2 are the partial pressures of oxygen in alveolar, expired, and inspired, gas, respectively, and VD/VT is the ratio of physiologic dead space over tidal volume). This shorter form is an algebraic identity of the classic equation. The shorter form involves the same assumptions and requires the same measurements as the traditional expressions but is more compact and easier to use in circumstances where VD/VT is measured routinely.

Air↗
PubMed1978

Lack of effect of helium breathing on catecholamine levels in the adrenal vein blood of the rabbit.

Catecholamine levels were measured in the adrenal vein blood of the chloralose anesthetized rabbit during periods of helium-oxygen breathing (50% He-50% O2) and of air breathing. Blood samples were taken from the T-arm of a venous shunt made by cannulating the renal vein proximally to the orifice of the adrenal vein and connecting the distal end of the cannula to one in the femoral vein. Adrenal vein blood flow varied from 0.09-0.30 g/min in five animals, and catecholamine release from 10-92 ng/min. There were large differences between levels from animal to animal but no significant differences in any one animal between levels measured while breathing helium and levels measured while breathing air. The same held true for respiratory rate, blood pressure, heart rate, and percent change in blood pressure during a simulated valsalva maneuver. Although there were changes seen in catecholamine release during some of these experiments, they could not be related to an effect of gases breathed. It is concluded that if there was an effect of helium breathing on catecholamine release in these anesthetized rabbits it was masked by other conditions with stronger action on the sympatho-adrenal system.

Adrenal Glands↗
PubMed1977

Insulin antibodies in the pathogenesis of insulin allergy and resistance.

Insulin allergy developed in a patient treated with beef/pork insulin. Desensitization therapy led to cessation of the allergy, but it was associated with the development of diabetic ketoacidosis with apparent insulin resistance which was successfully treated with fish insulin. The patient's initial serum contained a high titer of anti-insulin immunoglobulin E (IgE) antibody directed primarily against beef insulin. Desensitization therapy with pork insulin was associated with the production of anti-insulin immunoglobulin G (IgG) antibody with highest immunologic reactivity to pork insulin. This IgG antibody may have blocked the interaction of insulin with tissue-fixed IgE antibody but, in addition, led to significant increases in total serum insulin-binding capacity and transient insulin resistance. The favorable clinical response to fish insulin was likely due to the negligible immunologic reactivity of this patient's anti-insulin antibodies with fish insulin. This report suggests that desensitization therapy for insulin allergy can lead to insulin resistance of the immune type.

Animals↗
PubMed1977

Progressive hypereosinophilia with lung nodules due to thyroid carcinoma.

An elderly woman had dyspnea, a thyroid mass and multiple lung nodules on chest radiographs. She developed hypereosinophilia over a three-month period in which multiple diagnostic procedures were performed, without definition of the disease process. At post-mortem examination, the primary lesion was found to be a poorly differentiated carcinoma of the thyroid, metastatic to lung. This is the second case of hypereosinophilia related to metastatic thyroid carcinoma. The intensity of the hypereosinophilia in this case was increased by the administration of thyroid-stimulating hormone and by the development of necrosis of the lung nodules.

Aged↗
PubMed1977

Dyspnea in divers at 49.5 ATA: mechanical, not chemical in origin.

Pulmonary function was studied in six divers living in a hyperbaric chamber at a pressure nearly fifty times normal (49.5 atmospheres absolute (ATA), equivalent to 488 m or 1600 ft seawater (fsw)). As expected, ventilatory function was reduced. At 49.5 ATA, maximum voluntary ventilation (MVV) was 45% less than the control value. Instantaneous rates of gas flow during forced expiration were similarly reduced, especially those flow rates measured high in the lung volume. These reductions occurred despite an apparent increase in functional residual capacity (FRC) and the use of transpulmonary pressures considerably greater than those exerted during the same maneuvers at normal (sea-level) pressure. During underwater work at 49.5 ATA, the divers rapidly became exhausted at moderate levels of oxygen consumption (1.9 liters/min), showing severe dyspnea and impending syncope. These symptoms were not due to retention of carbon dioxide, nor to hemodynamic or metabolic causes. Thus, dense gas breathing, like asthma, exemplifies a state in which severe dyspnea may occur with normal or low arterial carbon dioxide and normal oxygen transport. The physiological adjustments the divers employed were similar to those seen in acute asthma, imposing an elastic load in addition to the flow-resistive work of breathing a gas mixture eight times as dense as air. Although men can do moderate work under conditions similar to those of this experiment, they will have only a limited physiological reserve available to meet the possibilities of emergencies or respiratory infections.

Adult↗
PubMed1976

Physiological responses of men working in 25.5 degrees C water, breathing air or helium tri-mix.

Fourteen scuba divers in swim trunks did ergometer work while breathing air at 3 m in 25.5 degrees C water. They were stressed by work and cold. Exercise produced increases in heart rate, minute ventilation (VE), oxygen consumption (VO2), and catecholamine excretion. Cold lowered rectal temperature (Tre) despite exercise, and contributed to the increase in VO2 and catecholamine excretion. Immersion, cutaneous vasoconstriction, work, and scuba breathing contributed to a brisk diuresis, probably by centralizing blood volume and thus stimulating central vascular volume receptors. Similar exercise in 25.5 degrees C water, breathing helium tri-mix (gas density less than air), produced higher VE but lower VO2 when compared to air breathing. Tri-mix scuba breathing resulted in a smaller diuresis, perhaps because its lower density leads to lesser atrial distension during work. The fall in Tre during work in 25.5 degrees C water was identical whether air or helium tri-mix was respired, since helium does not accentuate respiratory convective heat transfer.

Adult↗
PubMed1976

Technique for electrocardiographic monitoring of working divers.

An improved technique to record high-equality electrocardiographic (ECG) signals on the surface, from immersed humans during rest and exercise, in both normothermic and hypothermic exposures, has been devised. Recorded tracings were adequate for research purposes. Waveform signals obtained allow accurate continuous monitoring as well. The best recordings resulted from proper selection of electrode placement sites, careful preparation of the skin, and diligent protection of the skin-electrode interface. The resulting signals recorded from male divers working in 3.05 m (10 ft) of water contained very little artifact or shift in baseline of the ECG tracing. Post-dive examination of the placement sites showed neither separation of ECG electrodes from the skin nor intrusion of water between the electrode and skin surface. The relationship of the new ECG recording technique to a previously described system for acquiring physiologic data is described.

Diving↗