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Biomedical subjects

K Wasserman

Publications and source records attributed to K Wasserman.

At least 217 records · Page 12Linked to original sources
PubMed1979

Doxapram hydrochloride: a respiratory stimulant for patients with primary alveolar hypoventilation.

Four patients (ages 43 to 51) with primary alveolar hypoventilation (PAH) syndrome were studied to characterize the pharmacologic augmentation of ventilation with intravenous doxapram hydrochloride. Doxapram hydrochloride evoked a rapid ventilatory increase of 50 to 100 percent in all four subjects with a consequent decrease in arterial CO2 tension. Blood pressure and heart rate measurements showed small increases during the doxapram infusion. These responses, however, were only sustained during the infusion, decreasing to their predoxapram level when the drug was discontinued. The ventilatory response to the drug was more marked in the pressence of hypoxia than during high O2 breathing, suggesting that the carotid bodies are a site of action for this drug in man. Doxapram hydrochloride can be an effective respiratory stimulant in patients with PAH.

Doxapram↗
PubMed1978

Ventilatory and gas exchange responses to cycling with sinusoidally varying pedal rate.

To investigate factors controlling ventilation under conditions where the applied work load remains constant, but where hypothesized proprioceptive influences would be expected to vary, five subjects exercised at a constant work rate of 50 W on a cycle ergometer at pedaling rates which varied sinusoidally between 40 and 80 rpm. Each subject exercised continuously for 30 min at each of five sinusoidal periods. Minute ventilation (VE), carbon dioxide output (VCO2), oxygen uptake (VO2), and heart rate were computed breath-by-breath and amplitude and phase relations were extracted. We observed small fluctuations in VCO2 and VO2 engendered by varying metabolic requirements of moving the legs at varying rates. VE fluctuations were closely in phase with VCO2 and the amplitudes of the fluctuations were highly significantly correlated (r = 0.83, P less than 0.001); consequently end-tidal carbon dioxide tension fluctuations were small. Variation of pedaling rate, therefore, did not produce a ventilatory response independent of the effect of VCO2. The ventilatory responses to these forcings are inconsistent with an appreciable role for neurally mediated influences from the exercising limbs and provide further evidence that the exercise hyperpnea is linked to CO2 flow to the central circulation.

Adult↗
PubMed1978

Control of ventilation during intravenous CO2 loading in the awake dog.

The ventilatory response to venous CO2 loading and its effect on arterial CO2 tension was determined in five awake dogs. Blood, 200-500 ml/min, was diverted from a catheter in the right common carotid artery through a membrane gas exchanger and returned to the right jugular vein. CO2 loading was accomplished by changing the gas ventilating the gas exchanger from a mixture of 5% CO2 in air to 100% CO2. The ventilatory responses to this procedure were compared with those resulting from increased inspired CO2 concentrations (during which ventilation of the gas exchanger with the air and 5% CO2 mixture continued). The ventilatory response to each form of CO2 loading was computed as deltaVE/deltaPaco9. The mean ventilatory response to airway CO2 loading was 1.61 1/min per Torr PaCO2. The mean response for the venous CO2 loading was significantly higher and not significantly different from "infinite" CO2 sensitivity (i.e., isocapnic response). The results provide further evidence for a CO2-linked hyperpnea, not mediated by significant changes in mean arterial PCO2.

Animals↗
PubMed1978

A graphic approach to assessing interrelationships among minute ventilation, arterial carbon dioxide tension, and ratio of physiologic dead space to tidal volume in patients on respirators.

A graphic analysis of the relationships among minute ventilation, arterial PCO2, and the ratio of physiologic dead space to tidal volume is presented for the bedside clinical evaluation of patients receiving continuous respiratory support. With simultaneous measurement of minute ventilation and arterial PCO2, the graph can be used to determine the patient's ratio of dead space to tidal volume. This information can subsequently be used (1) for respirator adjustments to obtain the desired arterial PCO2; (2) to assess the severity of ventilation/perfusion unevenness; and (3) to follow the patient's response to respiratory therapy. It provides the clinician with a conceptual tool with which he can assess the status of a patient's gas exchange and more accurately evaluate and plan his course of treatment.

Carbon Dioxide↗
PubMed1977

Some respiratory and metabolic effects of exercise in moderately obese men.

The effects of varying levels of exercise on oxygen uptake, CO2 production, blood pressure, arterial blood gasses, and arterial concentrations of glucose, insulin, and growth hormone were examined in ten normal weight and ten moderately overweight young men. At comparable external work loads with a bicycle ergometer, the lean men required less oxygen than the obese men. When oxygen uptakes were matched during exercise on a treadmill, the lean men were walking on a steeper grade or at a higher rate than the obese men. The efficiency of exercise as assessed by the relation between oxygen uptake and work did not differ between the two groups. Blood pressure rose more in the obese during exercise than in the lean. The fall in lactate and rise in bicarbonate was of greater magnitude during cycle ergometry than during treadmill exercise. Obese and lean men, however, showed similar changes. With each level of exercise, there was a fall in arterial insulin levels, but the concentrations in the blood of overweight men always remained significantly above that of the normal men. Growth hormones tended to be higher in the normal weight men, but the differences were usually not significant, and there was no significant rise with exercise in either group until the highest levels of work were achieved. Glucose concentrations tended to be higher in the obese men, but fell to constant levels in both groups during exercise. Blood pressure rose to a greater extent in the overweight men during exercise.

Adolescent↗
PubMed1977

The clinical and physiological effect of whole-lung lavage in pulmonary alveolar proteinosis: a ten-year experience.

We have utilized whole-lung lavage in the successful treatment of 18 patients with pulmonary alveolar proteinosis. Our ten-year experience includes serial evaluations of patients with disabling lung dysfunction who had a total of 49 whole-lung lavages under general anesthesia. Clinical and physiological responses were documented both before and after each lavage. There were no complications or deaths. All patients were radiographically, physiologically, and symptomatically improved within hours after the procedures. Five patients required from two to four repeat lavages one to three years later. The treatment of this disorder has included a wide variety of techniques. We attribute our results to the use of a lung lavage technique that includes: (1) unilateral whole-lung lavages at two to three day intervals; (2) isotonic saline as the lavage solution; (3) use of a mechanical chest percussor during lavage; and (4) measuring the total thoracic compliance of each side in the immediate postlavage period as a guide for extubation. We conclude that whole-lung lavage is a safe, highly effective, repetitively applicable treatment for pulmonary alveolar proteinosis.

Adolescent↗
PubMed1977

Ventilatory and gas exchange dynamics in response to sinusoidal work.

The dynamic relationships between ventilation and gas exchange variables during exercise were determined utilizing frequency analysis techniques. Five subjects exercised on a cycle ergometer for 30 min at work rates which fluctuated sinusoidally between 25 W and 80% of the anaerobic threshold at sinusoidal periods of 0.7, 1,2,4,6, and 10 min. VE, VCO2, VO2, and HR were computed and displayed breath-by-breath. From these and steady-state response data, digital computer routines extracted amplitude and phase relations between each variable and the perturbing work load. These response characteristics were well described by first-order linear dynamics with time constants for VE, VCO2, VO2, and HR averaging 1.4, 1.2, 0.8, and 0.8 min, respectively. The time constants of VE and VCO2 were strongly correlated among subjects (r = 0.97). Further, there was no evidence that neural afferents from the exercising limbs induced fast components in the ventilatory response to these forcings. These results are consistent with the hypothesis that exercise hyperpnea is linked to metabolism via carbon dioxide production.

Adult↗
PubMed1977

Kinetics of gas exchange and ventilation in transitions from rest or prior exercise.

Seven normal subjects each performed three transitions to a subanaerobic threshold work rate on a cycle ergometer: 1) from rest, 2) from a low work rate (both at 60 rpm), and 3) from a low work rate at 40 rpm to the high work rate at 80 rpm. Oxygen uptake (VO2), carbon dioxide output (VCO2), and ventilation (VE) were computed breath-by-breath and response kinetics extracted. The mean half-times of VO2, VCO2, and VE were 32, 44, and 49 s, respectively, and were not appreciably affected by the prior exercise or by variation of pedal rate. The kinetics of VE was highly correlated with VCO2 (r = 0.94), with VCO2 leading VE, providing further description of the relation of the exercise hyperpnea to CO2 flow to the lungs.

Adolescent↗
PubMed1977

Dynamic imaging of the systemic perfusion of a lung cancer: case report.

Dynamic lung circulation scintigraphy employing intravenously administered 99mTc as pertechnetate was used to visualize the pulmonary arterial and systemic arterial circulations in a patient with bronchogenic carcinoma. Computer-processed dynamic images and region-of-interest data were utilized to demonstrate differences between tumor and normal regions regarding pulmonary and systemic blood supplies.

Animals↗
PubMed1976

Ventilatory responses to the metabolic acidosis of treadmill and cycle ergometry.

Ventilation and acid-base responses were studied at comparable levels of O2 uptake during cycle ergometer and treadmill exercise, to determine the extent to which the type of exercise affects these responses. Twenty male subjects performed 50-, 100-, and 150-W cycle ergometer exercise and three work rates of similar O2 uptake on a treadmill. At comparable oxygen uptakes, arterial lactate and VE were higher and arterial pH and bicarbonate were lower for cycle ergometer than treadmill exercise. These differences could be accounted for by the greater degree of metabolic acidosis during cycle ergometer work. The increment in VE over that predicted (from an extrapolation of the linear relationship of the VE-VO2 relationship for low work rates) was linearly related to the decrease in arterial bicarbonate; VE was increased by approximately 4 1/min for each meq/1 of bicarbonate decrease for both treadmill and cycle ergometry.

Acid-Base Equilibrium↗