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Biomedical subjects

W Chowanetz

Publications and source records attributed to W Chowanetz.

At least 19 recordsLinked to original sources
PubMed1992

[Interstitial lung diseases. A comparative study between a film-screen combination and a digital storage phosphor technic].

Chest examinations were carried out in 60 individuals using film-screen and digital storage phosphor techniques and identical radiation doses. 29 of these individuals were patients with interstitial pulmonary disease; 31 were normals. Postprocessing of the digital images was carried out with filtering using an unsharp mask and identical parameters for all patients. An ROC analysis using 10 observers showed no significant difference in the evaluation of the interstitial lung disease. Correlation analysis showed a significant positive correlation (p less than 0.001) for the findings in both techniques. Under the present circumstances, film-screen and digital storage phosphor technique are of equal value in the diagnosis of interstitial pulmonary disease.

Adult↗
PubMed1988

Differential effects of beta-adrenergic blockade on P0.1 and mean inspiratory flow.

To quantitatively examine and compare the effects of beta-adrenergic blockade on ventilation, we studied 20 healthy volunteers during inhalation of room air and at steady state CO2 (2.0, 4.4, 6.0%) following a single oral dose of bupranolol (vs. placebo). During room air breathing, minute ventilation (VE) and mean inspiratory flow (VT/TI) were significantly reduced after beta-blockade with a concomitant increase in blood PaCO2 (p less than 0.01). The timing factor TI/Ttot and mouth occlusion pressure P0.1 remained unchanged. These differences were, as shown from calculated effective alveolar ventilation, mainly attributed to a decrease in physiological dead space ventilation following beta-blockade. With a stepwise increase in FICO2, the difference in PaCO2 between placebo and bupranolol tended to approach zero, whereas VE and VT/TI remained significantly lower during beta-blockade (P less than 0.05). In contrast, no difference existed in P0.1 between bupranolol and placebo. We suggest that (1) respiratory drive assessed by P0.1 is unaffected by beta-blockade and (2) mean inspiratory flow depends also on CO2 elimination characteristics, which are influenced by beta-blockade.

Adult↗
PubMed1987

[Effect of bupranolol on hypoxic respiratory stimulation in healthy probands].

To determine whether hypoxic ventilatory response results, in part, from concomitant systemic sympathoadrenal stimulation, we studied ventilation in 20 healthy subjects before and after administration of a beta-blocking agent. A single oral dose of 100 mg bupranolol (vs placebo) significantly lowered minute ventilation from 9.4 +/- 0.7 to 8.3 +/- 0.2 l/min (mean +/- SEM) during normoxia, and from 10.8 +/- 0.8 to 8.9 +/- 0.2 l/min, when 11% O2 was inhaled. In our study, there were marked oscillations of ventilation on changing from room air to hypoxic breathing and back. They were ascribed to the preceding sampling of specimens for blood gas analysis. However, bupranolol had no influence on these transients. Bupranolol also had only slight cardiocirculatory effects during normoxia and did not prevent significant T-wave flattening, increase in heart rate, and fall in diastolic blood pressure during hypoxia. However, it did block the hypoxic increase in systolic blood pressure. From our results we suggest that (1) in spontaneously breathing conscious subjects, hypoxia-induced hyperventilation is also due to hypoxic sympathoadrenal activity and individual mental state, and (2) these influences do not affect all aspects of the cardiocirculatory response.

Adult↗
PubMed1987

[Efficacy of nasal O2 administration during mouth breathing].

27 subjects with healthy lungs received during conscious mouth breathing of room air simultaneously also nasally applied O2. The mean O2 concentration of the expiratory air at the mouth was a measure for the effective inspiratory oxygen concentration. Application through a nasal mask at 4 l/min O2 flow proved only slightly superior to the airtight nose frame (25.2 vs 23.6 per cent by volume O2), whereas the highest concentration was achieved by mask and reservoir (35.3 vol.%; 2P less than 0.001). The five habitual mouth breathers of the subject group did not show any O2 uptake through the nose in any of the experiments, the mean nasal share of the inspiration being calculated at 2.5% against 25% for the other subjects (2P less than 0.001). The interindividual differences proved independent of nose resistance and are ascribed to changing active positioning of the soft palate. This mechanism must be taken into consideration when assessing the arterial blood gases in oronasal respiration.

Adult↗
PubMed1987

[Mechanisms of supralaryngeal airway obstruction in normal persons and habitual mouth breathers].

We examined oronasal flow partitioning in 27 volunteers with normal or slightly increased nasal resistance (mean +/- SD, 0.24 +/- 0.19 kPa/l/s). Mean percentage of inspiratory nasal flow contribution was measured during spontaneous oronasal breathing. The averaged nasal admixture of airflow differed considerably within and between all subjects (mean +/- SD, 20.9% +/- 16.5%; range 1%-70%), showing no correlation to nasal resistance. Five of 27 subjects with a history of habitual mouth breathing had a significantly lower nasal admixture as compared with controls (2.5% +/- 1.7% vs 25.1% +/- 15.4%; P less than 0.005), but with no statistical difference in nasal resistance. To evaluate the hypothesis that velopharyngeal narrowing is due to an increased tone of the soft palate, measurements were also performed under positive nasal pressure, inspiratory resistive loading at the mouth, and during breath-holding. There was no significant difference of airflow distribution between these modifications and unloaded breathing in either group. These data suggest, therefore, that oronasal flow distribution is due to active positioning of the soft palate, and that habitual mouth breathing without any nasal obstruction may be associated with closure of the velopharyngeal isthmus as a consequence of disturbed neural control mechanisms.

Adult↗
PubMed1986

[Role of the nose in inspiration in mouth breathing: quantitative determination by analysis of expiratory gases].

It is widely accepted that increased nasal resistance plays a major role in habitual mouth breathing. We investigated oronasal air flow distribution during voluntary mouth breathing in subjects without nasal obstruction. To determine whether nasal air flow contributes to total inspiratory flow, we administered 100% O2 by a nasal mask while the lips were kept apart by a mouth piece. Expired O2 concentrations measured at the mouth were a sensitive indicator of nasal admixture during inspiration. Theoretical considerations predict that mixed expired pO2 from two consecutive steady state periods should allow calculation of nasal admixture. Measurements made on 22 healthy volunteers revealed a very variable degree of nasal contribution to inspiratory air flow (mean +/- SD, 25 +/- 15%, range 3-70%). There was no correlation between this proportion and anthropometric data, smoking habits, nasal resistance, or presence of rhinitis. We suggest that changes in the position of the soft palate, tongue, and/or pharyngeal wall associated with respiration are mainly responsible for the within and between subject variation observed in this study. This explanation is consistent with recent experimental findings on the pharyngeal dilating muscles.

Adolescent↗
PubMed1982

[Terbutaline-induced metabolic responses after propranolol and metoprolol].

Subcutaneously administered terbutaline (7 micrograms/kg Bricanyl) induced typical changes in carbohydrate and fat metabolism and cardiovascular effects in ten healthy volunteers. A significant inhibition of changes in systolic and diastolic blood pressure, heart rate and plasma glycerol, FFA, lactate and potassium levels was seen after pretreatment with 0.1 mg/kg propranolol (Dociton) or 0.2 mg/kg metoprolol (Beloc). Intravenous metoprolol showed weaker beta-blocking activity than propranolol, but proved to be more effective in its action on systolic blood pressure.

Adult↗
PubMed1979

[Effects of propranolol and metoprolol on beta-adrenergic metabolic responses (author's transl)].

In ten healthy volunteers infusion of 7 micrograms/kg orciprenaline produced typical changes in carbohydrate and fat metabolism due to beta-adrenergic stimulation. Pretreatment with intravenously administered propranolol or metoprolol significantly inhibited orciprenaline-induced changes in systolic blood pressure, heart rate and plasma FFA, potassium, glucose and glycerol levels. Propranolol (0.1 mg/kg) seemed to be more effective than metoprolol (0.2 mg/kg) even in inhibiting predominantly beta 1-adrenergic responses.

Adult↗
PubMed1978

[Functional effects of micro-oil embolization following lymphography].

Lymphography, if performed correctly, has few clinically relevant complications. Nevertheless, the passage of oily contrast medium into the pulmonary vascular bed along physiological pathways can usually be verified radiographically and functionally. Since that part of the contrast medium filtered in the lungs is of no diagnostic value we think that a total amount of 14--16 ml Lipiodol Ultrafluid should normally suffice for outlining the retroperitoneal lymph passageways from the legs. With smaller amounts one may misinterpret an incomplete filling of the cranial paraaortic lymph nodes as filling defects. We agree with most authors that in patients with abnormal lung function, especially those with restrictive disorders, and in patients with pre-existing right heart strain lymphography should only be considered when truly indicated and only after testing of pulmonary function.

Contrast Media↗
PubMed1977

[Therapy of the bronchitic syndrome in the elderly].

The prophylactic means and general modes in the treatment of the bronchitic syndrome in geriatric patients are outlined. The therapy is discussed with respect to the use of broncholytics, secretolytics and steroids on the basics of a detailed lung function test. The altered health condition of the geriatric patient needs an intensive and detailed therapy program and must include limitations caused by the old age.

Aged↗
PubMed1977

[Diagnosis of the bronchitic syndrome in the aged].

The cumulation of exogenic factors on the basis of an endogenic disposition and the addition of physiologic aging processes cause an increase of the "bronchitic syndrome" in old age. Heart insufficiency, tuberculosis, lung embolism and bronchial carcinoma are the important differential diagnostic aspects in these patients. The structural and functional changes of the lung in old people and the polypathy, resp. multimorbidity of the whole organism cause the complications and disadvantageous interferences. The prognostic important disturbances of the ventilation mechanics are early recognizable with new diagnostic tools, particularly with the whole body plethysmography.

Aged↗