Biomedical subjects

B A Staats

Publications and source records attributed to B A Staats.

35 records · Page 2Linked to original sources

PubMed1988

Impaired exercise tolerance after inferior vena caval interruption.

Four patients were evaluated for persistent dyspnea eight months to four years after inferior vena caval interruption for treatment of pulmonary emboli. Maximal exercise testing with gas-exchange analysis was performed. All patients attained less than 64 percent of predicted maximal oxygen uptake. Peak exercise heart rates were 85 percent or greater of predicted values. Arterial hypoxemia was not observed. The ratio of dead space to tidal volume (VD/VT) decreased with exercise, and the ratios of maximal exercise ventilation to maximal voluntary ventilation (VE/MVV) were less than 67 percent. These results suggest a cardiac rather than a ventilatory limitation to exercise. Inadequate venous blood return to the heart is the likely mechanism for the impaired exercise performances.

Adult↗

PubMed1987

Cardiorespiratory function in asymptomatic survivors of neonatal respiratory distress syndrome.

We measured cardiopulmonary function at rest and during exercise in 15 healthy survivors of neonatal respiratory distress syndrome (RDS) and compared the results with those in 15 normal subjects. The mean birth weight of the RDS group was 1,771 g, and 12 of the 15 patients had required endotracheal intubation. The oxygen scores ranged from 79 to 3,322. Five of the 15 RDS patients had abnormal results of pulmonary function studies at rest. Peak expiratory flow was lower (P less than 0.05) in the RDS group (2.98 liters/min) than in the control group (3.57 liters/min). A negative correlation was noted between the forced expiratory flow between 25 and 75% of vital capacity and the oxygen score in these patients. Exercise tolerance was below normal in two of the RDS patients, both of whom also had abnormal pulmonary function at rest. One patient in the RDS group had systemic arterial hypertension at rest and during exercise. No significant differences in exercise tolerance or the cardiorespiratory response to exercise were observed between the two groups.

Child↗

PubMed1987

Smoking and cough syncope: follow-up in 45 cases.

A follow-up review of 45 patients with cough syncope was performed to ascertain the effect of therapy in relieving symptoms. These patients constituted 2.5% of all Mayo Clinic patients evaluated over a 3-year period for syncope. Cough syncope patients were predominantly male (43:2), the average weight was 96.1 kg, and the average age was 53.2 years. Eighty-two percent were current or ex-smokers at the time of the initial evaluation and 86% of those having pulmonary function tests demonstrated findings consistent with obstructive lung disease. Treatment was determined by their primary physician and, in general, was aimed at decreasing the cough. Cough-related symptoms were abolished or improved in 97% of patients. Smoking cessation was closely associated with decreased symptoms. Although felt by both patient and physician to be a benign disorder, cough syncope can result in severe bodily injury. Patients with a vigorous cough, especially smokers, should be questioned thoroughly about cough syncope. Treatment of cough is effective in relieving symptoms.

Adult↗

PubMed1987

Progesterone-induced changes in exercise performance and ventilatory response.

To further study the relationship between ventilatory response (VR) and exercise performance, and to investigate to what extent progesterone is responsible for ventilatory changes in the luteal phase of the menstrual cycle, we administered medroxyprogesterone acetate (MPA) to 10 normal males (20 mg three times a day for 5 doses) and compared results with those obtained in a similar study of females. With MPA, there was an increase in the resting VR to hypercapnia; the resting VR to hypoxia was not changed. There was a respiratory alkalosis at rest. During exercise, the PaCO2 remained lower but the pHa was not different because of a tendency toward lower bicarbonate concentration with MPA. Ventilation, when related to CO2 output, was increased at all exercise loads, indicating increased VR to endogenous CO2. However, ventilation was only minimally (3%) increased when related to oxygen uptake or workload. This apparent disparity is because of slightly lower CO2 output at a given oxygen uptake with MPA. As in females, maximal duration of exercise and maximal oxygen uptake were unchanged. Except for degree, MPA induced all the ventilatory changes seen in the menstrual cycle. Increased VR does not adversely affect exercise performance.

Adult↗

PubMed1987

Exercise performance and ventilatory response in the menstrual cycle.

We investigated the effects of the luteal phase of the menstrual cycle, as compared with the follicular phase, on ventilatory response (VR) and exercise performance in eight normally menstruating, non-athletic women. Subjects were studied near the predicted mid-point of each phase which was later documented by serum progesterone level. Resting VR to hypercapnia was greater, and VR to hypoxia tended to be greater in the luteal phase than in the follicular phase, but the increases in VRs were unrelated to progesterone level. There were no differences in maximal oxygen uptake, maximal duration of exercise, maximal heart rate, work efficiency, maximal ventilation (VE), anaerobic (ventilatory) threshold, gas exchange, cardiac output, or oxygen delivery. The PaCO2 was lower, and pHa tended to be higher during exercise. VE per unit CO2 output (VE/VCO2) was increased. R values (VCO2/VO2) were less, and maximal lactate values tended to be less, suggestive of increased dependence on fat for energy metabolism. At a given workload, exercise VE was unchanged due to the effect of less CO2 output at a given VO2 (lower R), balancing increased VE/VCO2. We conclude that, although ventilatory parameters are altered by the menstrual cycle, there is no overall effect on maximal exercise performance.

Adult↗

PubMed1986

Exercise tolerance and cardiorespiratory response to exercise after the Fontan operation for tricuspid atresia or functional single ventricle.

To determine the impact of the Fontan operation on exercise tolerance and on the cardiorespiratory response to exercise, we compared the results of graded exercise to maximal effort of 81 patients with tricuspid atresia or single functional ventricle studied preoperatively with those of 29 patients studied postoperatively. Postoperatively, the values for total work performed, duration of exercise and maximal oxygen uptake increased significantly. Regardless of operative status, the maximal heart rate during exercise was reduced. The cardiac output and stroke volume response to exercise were subnormal after operation. Systemic arterial blood oxygen saturation was reduced markedly preoperatively both at rest and during exercise; postoperatively, it was significantly greater than the preoperative value but it remained slightly abnormal. The ventilatory response to exercise (respiratory rate, minute ventilation and ventilatory equivalent for oxygen) decreased toward normal after operation. Exercise tolerance and the cardiorespiratory responses to exercise improve after the Fontan operation. Formal exercise testing is essential to quantitate the degree of improvement.

Adolescent↗

PubMed1986

Pulmonary function in relapsing polychondritis.

The pulmonary mechanics and bronchoscopic findings in 5 patients with relapsing polychondritis were studied to evaluate the mechanism of obstruction. Two of the patients did not have clinical symptoms referable to the respiratory tract: pulmonary function was normal in 1 patient and was suggestive of mild restriction in the other. Three patients had dyspnea; pulmonary function studies revealed expiratory and inspiratory obstruction in all 3. The maximal flow-static recoil curves demonstrated that the expiratory obstruction was due predominantly to airway abnormality and not to loss of elastic recoil forces of the lung. The bronchoscopic appearance of the extrathoracic airway during quiet breathing did not accurately reflect pulmonary function results. One patient had a visually normal upper airway but greatly reduced maximal inspiratory flow rates, whereas another patient had pronounced narrowing of the upper airway but only a modest reduction of maximal inspiratory flow rates. The bronchoscopic appearance of the intrathoracic airway during quiet breathing did relate well to maximal expiratory flow rates. We conclude that in our group of patients the predominant mechanism of expiratory obstruction in relapsing polychondritis is due to airway abnormality. Although the bronchoscopic and radiographic findings are useful, spirometry is more important in determining functional abnormality.

Adrenal Cortex Hormones↗

PubMed1986

Pulmonary hypertension, hemolytic anemia, and renal failure. A mitomycin-associated syndrome.

After treatment with mitomycin C, a patient developed pulmonary hypertension with interstitial infiltrates, microangiopathic hemolytic anemia, systemic hypertension, and renal failure with the nephrotic syndrome. Open lung biopsy documented intracapillary fibrin thrombi in the pulmonary vasculature. Renal biopsy documented glomerular and arteriolar changes that were most consistent with a thrombotic-thrombocytopenic-like process. Treatment with corticosteroids, fresh-frozen plasma, and total plasma exchange was ineffective. The patient died six months after the onset. When mitomycin-C therapy is given, the clinician should be aware of the pulmonary, renal, and microangiopathic changes that can be associated with such therapy.

Adenocarcinoma↗

PubMed1985

Effect of resection of the sternum and manubrium in conjunction with muscle transposition on pulmonary function.

We recorded the changes in pulmonary function that occurred after removal of the sternum and manubrium and repair by pectoralis major muscle transposition in six patients. Of these patients, three had osteomyelitis of the manubrium and sternum, two had osteosarcoma of the sternum, and one had osteomyelitis and radionecrosis of the manubrium and sternum. Body plethysmography and the rebreathing, hypercapnic ventilatory response test with inductive plethysmographic recordings of chest-wall motion were performed preoperatively and postoperatively. Preoperatively, four of the six patients had evidence of mild to moderate chest-wall restriction. Pulmonary function was normal in the other two patients. Postoperatively, total lung capacity was unchanged but the vital capacity decreased 11.5% in the overall group. Static compliance, retractive force, and the steady-state diffusing capacity for carbon monoxide decreased modestly but significantly postoperatively. The expiratory flow rates and maximal voluntary ventilation remained unchanged. Preoperatively, the slope of the hypercapnic ventilatory response was less than that predicted. Postoperatively, the slope did not change. In three patients, however, increased dependence on the abdomen for breathing suggested a dynamic restriction of rib-cage motion. On the basis of our findings, we conclude that surgical removal of the sternum and manubrium in conjunction with muscle flap repair is a well-tolerated procedure. Any postoperative changes in pulmonary function are minor.

Adolescent↗

PubMed1985

Direct and indirect blood pressure during exercise.

In 27 subjects, we compared rest and exercise blood pressure (BP) measurements determined directly by catheterization of the radial artery with simultaneous values obtained indirectly by auscultation of the brachial artery. As work increased, the systolic BP increased, whereas the diastolic BP did not change. Considering all comparisons, direct BP was greater than indirect BP by a mean of 29.0 mm Hg for systolic BP and 12.3 mm Hg for diastolic BP. As exercise level increased, the difference between direct and indirect systolic BP decreased whereas the difference between direct and indirect diastolic BP did not change. Both methods have advantages for assessment of BP response to exercise: normality of BP response is best assessed by auscultation, whereas beat-by-beat trends in BP are more accurately defined by the direct method.

Adolescent↗

PubMed1984

Functional single ventricle: cardiorespiratory response to exercise.

The cardiorespiratory response to exercise was measured in 27 children with functional single ventricle. All 27 patients had a significant reduction in exercise time, work performed, maximal exercise heart rate, maximal oxygen uptake and systemic arterial blood oxygen saturation. The reduction in exercise performance increased with increasing age of the patients. All patients ventilated excessively at rest and during exercise. This study documented the precise level of exercise intolerance in patients with functional single ventricle. The progressive deterioration in exercise performance with increasing patient age may lend credence to the concept that operation for physiologic correction of functional single ventricle should be considered during or before adolescence.

Adolescent↗

PubMed1984

Chest wall motion in sleep apnea.

Patterns of rib cage (RC) and abdomen (ABD) motion obtained from a respiratory inductive plethysmograph were studied during disordered breathing events - obstructive apnea, obstructive hypopnea, mixed apnea, and central apnea - in 54 patients with sleep apnea. The type of disordered breathing event was verified by esophageal pressure and bias-flow mask recordings. Obstructive apnea occurred to a variable extent in all patients and was characterized by stereotyped paradoxical motion of the RC or ABD or both in 49 patients (91%). There was no paradox in 2 patients with "feeble" inspiratory effort during obstructions and in 3 patients with normal inspiratory effort during obstructed breaths. The more obese patients displayed paradox of the ABD rather than of the RC. Paradox did not occur in central apnea or in the central component of mixed apnea. Obstructive hypopnea was characterized by paradox during part of the breath. We conclude that RC and ABD motion can adequately characterize apnea in most patients and thus avoid invasive monitoring techniques that can adversely affect sleep. However, if chest wall motion suggests that all apneas are central, a direct measurement of respiratory effort is necessary to exclude obstruction.

Adult↗

PubMed1983

Upper airway obstruction and disordered nocturnal breathing in children.

Fourteen children with disordered breathing during sleep (obstructive apnea, obstructive hypopnea, or snoring) and anatomic obstruction of the upper airway were studied. Twelve children had hypertrophied tonsils and adenoids, and two had a deviated nasal septum. No child had sequelae of severe sleep apnea--that is, cor pulmonale, pulmonary hypertension, or alveolar hypoventilation. Results of polysomnographic studies were abnormal in all and revealed that obstructive hypopnea (increased respiratory effort with decreased airflow) was more common than obstructive apnea (increased respiratory effort without airflow). Surgical removal or correction of the upper airway obstructive lesion in 12 children resulted in normal nocturnal respiration. Surgical intervention was declined in two patients, and their symptoms persist. We conclude that surgical removal of upper airway obstructive lesions in children with disturbed nocturnal sleep should not be reserved only for those with serious sequelae of obstructive sleep apnea; considerable benefit is gained in selected patients with mild obstructive sleep apnea or hypopnea.

Adenoids↗

PubMed1982

Symptomatic pectus deformities of the chest.

Aspects of pulmonary mechanics and exercise tolerance were investigated in 8 young male patients with pectus deformities, 5 of whom presented with the chief complaint of exercise limitation. Results of pulmonary mechanics studies did not adequately explain patient symptoms. Lung volumes were only mildly reduced. There was no evidence of airway obstruction. Measures of lung compliance were normal in 6 patients studied. Results of exercise studies did reveal significant abnormalities in symptomatic and asymptomatic patients; tidal volume at maximal effort expressed as a percentage of vital capacity was diminished, suggesting restriction of ventilation. Oxygen uptakes in the 4 symptomatic patients were normal at lesser work loads but progressively exceeded predicted values at greater work loads, suggesting an abnormally elevated work of breathing during vigorous exertion. Three asymptomatic patients demonstrated a normal linear pattern of increase in oxygen uptake with increasing work load. Respiratory symptoms in some patients with pectus deformities appear to have a physiologic basis. Our data suggest a dynamic restrictive pulmonary process as an explanation for these symptoms.

Adolescent↗

PubMed1980

Viscosity and density dependence during maximal flow in man.

Maximal expiratory flow curves were obtained from ten healthy subjects white breathing air and three other gas mixtures with different densities and viscosities. From these data, the magnitudes of the dependence of maximal flow on gas density and viscosity were obtained. The scaling laws of fluid mechanics, together with a model for the flow-limiting mechanism, were used to obtain a prediction of the relationship between the density dependence and the viscosity dependence of maximal flow. Although the data for individual subjects were too variable to allow a precise comparison with this prediction, the relationship between the mean density dependence and the mean viscosity dependence of all usbjects agreed with the theoretic prediction. This agreement supports the assumption, which is frequently made, that flow resistance rather than tissue visoelasticity is the dominant contributor to peripheral resistance. Information on the relationships between the pressure drop to the flow-limiting segment and flow, gas density and viscosity, and lung volume were also obtained.

Air↗

PubMed1980

The lipoprotein profile of chylous and nonchylous pleural effusions.

The lipoprotein electrophoregrams and the cholesterol and triglyceride levels of the pleural fluid were evaluated for patients with chylous pleural effusions, as defined by the presence of a distinctive band of chylomicrons on the lipoprotein electrophoregram, and in patients with nonchylous effusions of various causes. One hundred forty-one patients were studied during a 3-year period. The chylous effusions had strikingly higher triglyceride levels (median 249, range 49 to 2,270 mg/dl) than the nonchylous group (median 33, range 13 to 107 mg/dl); there were no significant differences in cholesterol or protein between the two groups. The gross description of the fluid was a poor indicator of its origin, being described as consistent with chyle in less than 50% of cases of chylous effusions. The triglyceride values distinguished chylous effusion from nonchylous effusion; values greater than 110 mg/dl are highly suggestive of a chylous effusion. Equivocal cases--triglyceride values between 50 and 110 mg/dl--required lipoprotein analysis. Pleural effusions of undetermined cause, regardless of gross appearance of the fluid, require that a screening triglyceride value be obtained to rule out a chylous effusion.

Cholesterol↗

PubMedDate not supplied

Surgically correctable causes of sleep apnea syndrome.

This report presents six cases of obstructive sleep apnea associated with discrete anatomic abnormalities of the upper airway tract. All patients were relieved of their sleep apnea by surgical correction of the airway obstruction, and therefore permanent tracheotomy was avoided. The obstructive causative factors were nasal septal deformity, adenoidal hypertrophy, nasopharyngeal stenosis, lingual cyst, lingual tonsillar hypertrophy, and laryngeal cyst. The last-named four conditions have not previously been reported as correctable causes of sleep apnea.

Adolescent↗