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Biomedical subjects

M Gugger

Publications and source records attributed to M Gugger.

At least 19 recordsLinked to original sources
PubMed1992

Effect of reduced expiratory pressure on pharyngeal size during nasal positive airway pressure in patients with sleep apnoea: evaluation by continuous computed tomography.

BACKGROUND: This study aimed to determine whether reducing the expiratory pressure during nasal positive airway pressure for reasons of comfort causes a substantial decrease in the upper airway calibre. METHODS: Eight patients with obstructive sleep apnoea were studied. Continuous computed tomography (each run lasting 12 seconds) was used to measure minimum and maximum pharyngeal cross sectional areas at the velopharynx and the hypopharynx. Pharyngeal areas were measured while patients were awake and breathing without assistance, during the application of 12 cm H2O continuous positive airway pressure, and during bi-level positive airway pressure with an inspiratory pressure of 12 cm H2O and an expiratory pressure of 6 cm H2O. RESULTS: Nasal continuous positive airway pressure significantly increased the mean minimum and maximum upper airway areas at both the velopharynx and the hypopharynx compared with normal unassisted breathing. Bi-level positive airway pressure did not show a statistically significant increase in the minimum upper airway area at either level compared with normal unassisted breathing. The minimum areas of the velopharynx and hypopharynx were smaller with bi-level than continuous positive airways pressure in six of eight and eight of eight patients respectively but these were still greater than during unassisted breathing in seven of eight and six of eight patients respectively. CONCLUSIONS: Continuous positive airway pressure at 12 cm H2O is more effective in splinting the pharynx open than bi-level positive airway pressure with an inspiratory positive airway pressure of 12 cm H2O and an expiratory pressure of 6 cm H2O in patients with obstructive sleep apnoea during wakefulness, suggesting an important role for expiratory positive airway pressure. The clinical importance of this finding needs to be evaluated during sleep.

Humans↗
PubMed1992

[Asthma and sleep].

In asthmatics, nocturnal cough and dyspnea are much more common than generally known. Therefore, patients with asthma must be asked specifically whether they suffer from symptoms of asthma at night. Usually, nocturnal wheezing is a sign of a badly controlled asthma. Nocturnal bronchoconstriction appears to be an exaggeration of the normal circadian changes in airway calibre. The cause of this exaggeration is not well understood, and it's origin is presumably multifactorial. Careful treatment of nocturnal asthma is particularly important because many deaths due to asthma occur at night and because regular disturbance of sleep impairs performance during the day. Inhaled corticosteroids and beta 2 agonists, especially the new long-acting beta agonists, are first-line drugs for therapy.

Airway Resistance↗
PubMed1991

[Tuberculous pleuritis in pre-existent sarcoidosis].

The coexistence of the two granulomatous diseases sarcoidosis and tuberculosis in the same patient is rare and can raise diagnostic problems. We report a case of this kind in a 31-year-old man and discuss the diagnostic investigations, some of which can be misleading. In a patient with sarcoidosis and pleural effusion the possibility of tuberculosis must be ruled out, if necessary invasively.

Adult↗
PubMed1991

Extent of pulmonary emphysema in man and its relation to the loss of elastic recoil.

1. We assessed lung density, determined by computerized tomography, as a measure of emphysema and related this to lung function and measurement of the elastic recoil of the lung in normal subjects and patients with chronic obstructive lung disease. 2. We found a significant correlation between measurements of elastic recoil pressure at 90% of total lung capacity and both the forced expiratory volume in 1 s (r = 0.80, P less than 0.001) and the transfer factor for carbon monoxide (r = 0.70, P less than 0.001). Measurements of elastic recoil of the lung also correlated with lung density as measured by computerized tomography scanning (P less than 0.001). 3. Multiple regression analysis demonstrated a correlation between the density of the lowest fifth percentile of the computerized tomography lung-density histogram, and both the natural logarithm of the shape parameter of the pressure-volume curve (P less than 0.01), and the transfer factor for carbon monoxide (P less than 0.01). However, the mean computerized tomography lung density correlated, in addition, with the elastic recoil pressure of the lungs at 90% of total lung capacity (P less than 0.001). 4. Since the elastic recoil pressure correlates with computerized tomography lung density, and hence with emphysema, and since elastic recoil pressure also correlates with the forced expiratory volume in 1 s, these results suggest that loss of elastic recoil is one determinant of airflow limitation in patients with chronic obstructive lung disease.

Adult↗
PubMed1991

Accuracy of respiratory inductive plethysmograph in measuring tidal volume during sleep.

Respiratory inductance plethysmography (RIP) has been widely used to measure ventilation during sleep, but its accuracy in this role has not been adequately tested. We have thus examined the accuracy of the RIP by comparing tidal volume measured with RIP with that measured by a pneumotachograph in eight unrestrained normal subjects during sleep. We have also studied the effect of posture on the accuracy of the RIP. In all sleep stages the correlation between RIP tidal volume measurements and expired volume showed relatively poor correlations (mean r = 0.49-0.60), and the bias of the measurements varied widely. Changes in posture altered the correlations between the two measurements, with no systematic differences between positions. When the subjects resumed a position, the 95% confidence intervals of tidal volume measurement did not overlap the original confidence limits in that posture on 13 of 25 occasions. This study shows that the RIP does not accurately measure tidal volume during sleep in unrestrained subjects and should only be used for semiquantitative assessment of ventilation during sleep.

Adult↗
PubMed1991

[Pulmonary causes of abnormal fatigability].

Abnormal physical exhaustion and fatigue are often simply regarded as a natural consequence of pulmonary diseases. Apart from factors not specifically related to pulmonary diseases (e.g. consequences of infections or malignant diseases of the lungs), increased work of breathing due to impaired lung/thoracic cage mechanics, the effects of chronic hypoxia and hypercapnia, the consequences of disturbed sleep and psychosocial factors are mainly responsible for the impaired physical fitness and the fatigue in association with lung diseases. A careful case history including psychosocial aspects and a thorough physical examination are essential for an efficient diagnostic evaluation. Tests of pulmonary function not only in the awake patient at rest, but also during sleep or adequate physical exercise can reveal the causes of impaired physical performance and fatigue related to lung diseases.

Asthma↗
PubMed1990

[When does snoring need assessment?].

Snoring and obstructive sleep apnea (OSA) are both related to narrowing of the upper airways during sleep. However, because the sex ratios of snoring and OSA are very different, snoring cannot simply be regarded as a preapneic state. Symptoms of OSA, a potentially life-threatening disorder, include excessive daytime sleepiness, nocturnal breath cessation and snoring and gasping. Most patients are obese, hypertensive men who eventually develop cardiovascular abnormalities. Snoring patients only need sleep laboratory evaluation if OSA is suspected based on clinical information.

Humans↗
PubMed1990

A new method of analysing pulmonary quasi-static pressure-volume curves in normal subjects and in patients with chronic airflow obstruction.

1. Exponential analysis of lung pressure-volume curves is used to deal with the non-linearity of the pressure-volume relationship. A major problem of this procedure is to define the lower volume limit for exponential curve fitting. 2. In 12 healthy subjects and 24 patients with chronic airflow obstruction, a cubic function was fitted to the quasi-static pressure-volume curves to define an inflection point. 3. The exponential function of Colebatch et al. (Colebatch, H.J.H., Ng, C.K.Y. & Nikov, N.J. Applied Physiol. 1979; 46, 387-93) was then fitted to the data for volumes above the inflection point. 4. Exponential analysis with a cubic determination of an inflection point provides an objective way to describe the elastic properties of the human lungs in vivo.

Adult↗
PubMed1990

[Pathophysiology of respiratory insufficiency in neuromuscular diseases].

In end stage neuromuscular disease respiratory muscle fatigue can lead to respiratory failure. There is no close correlation between the degree of peripheral muscle weakness and the weakness of the respiratory muscles. Early in the disease the maximum in- and expiratory pressures can be abnormal even though the results of spirometry are normal. Progressive weakness of the respiratory muscles results in a decrease in vital capacity and eventually in alveolar hypoventilation, especially during sleep. General muscle weakness and fatigue may be the reasons why sleep hypoventilation is often overlooked in its early stages. Dyspnea may be a early symptom but it is not unusual that alveolar hypoventilation remains undetected until complications ensue (Cor pulmonale, polycythemia, altered alertness).

Humans↗
PubMed1990

[Mechanical home ventilation--methods and technique].

With modern ventilators it is now possible to ventilate patients with severe respiratory failure during the night (or for longer periods) in their homes without the need for tracheotomy. At present the nocturnal nasal ventilation with intermittent positive pressure seems to become the method of choice. However also negative pressure ventilation is successful in many cases. The indications for home mechanical ventilation are briefly presented and the different techniques explained in some detail.

Home Care Services↗
PubMed1989

[Remission of a sleep apnea syndrome following aortocoronary bypass surgery].

It is well known that sleep apnea syndrome may develop or worsen in patients with cardiac failure. The case is reported of a patient with severe coronary artery disease involving three vessels but without symptoms or signs of cardiac failure. Aortocoronary bypass operation nevertheless eliminated the coexisting sleep apnea syndrome.

Aged↗
PubMed1989

Changes in serum potassium concentration in asthmatic and normal subjects during exercise.

Serum potassium concentrations were measured before, during, and after exercise in 32 patients with asthma (12 with exercise induced asthma), and in seven normal subjects. The changes in serum potassium in response to exercise did not differ significantly in the two groups or between those with and without exercise induced asthma. The potassium response to exercise is unlikely to be relevant to the mechanism underlying exercise induced bronchoconstriction.

Adult↗
PubMed1989

Ventilatory and arousal responses to added inspiratory resistance during sleep.

Airway resistance increases during sleep. We have determined the ventilatory and arousal responses to the addition of inspiratory resistance of 4, 7, or 10 cmH2O/L/s during sleep in 10 normal men who slept wearing valved face masks. Insufficient ventilatory response data were obtained during rapid eye movement (REM) sleep to allow adequate analysis. The immediate responses to loading were decreases in tidal volume (VT), breathing frequency (f), and minute ventilation (VE), with no difference between wakefulness and Stage 2 and Stage 3/4 sleep in the effects of loading on VT and VE, but f fell more during wakefulness than during sleep (p less than 0.05) because of a greater lengthening of inspired time (TI) (p less than 0.05). During the first 10 breaths, occlusion pressure (P0.1) increased similarly in all EEG stages. Averaging responses during the 2-min periods when resistances were applied, the only variable to differ between EEG stages was TI, which increased more in wakefulness than in Stage 2 or Stage 3/4 sleep (p less than 0.01). Arousal within 2 min of application of resistance occurred less frequently from Stage 3/4 sleep than from Stage 2 or REM sleep (p less than 0.02). The study demonstrates that sleep modifies the changes in respiratory timing produced by resistive loading without having a major effect on ventilation or P0.1 responses. The low frequency of arousal from Stage 3/4 sleep with loading may explain why asthmatics rarely awaken from this stage with wheeze.

Adult↗
PubMed1988

Low plasma concentrations of ionized calcium in patients with asthma.

It has been suggested that calcium homeostasis is abnormal in the vascular smooth muscle of hypertensive patients and in the bronchial smooth muscle in asthmatics. We have found the mean baseline concentration of plasma ionized calcium to be significantly lower both in 12 asthmatics with exercise-induced asthma (EIA) [1.16 +/- 0.01 (SE) mmol/l, P less than 0.001] and in 20 asthmatics without EIA (1.16 +/- 0.01; P less than 0.001) compared with 42 healthy subjects (1.24 +/- 0.01). The mean concentrations of plasma ionized calcium were not significantly different in asthmatics with and without EIA when measured either before treadmill exercise, during the last seconds of this exercise, or 10 or 20 min after exercise but were significantly lower than in another seven healthy subjects who undertook the same exercise protocol. Total plasma calcium concentrations in the three exercising groups were not significantly different at any point in time. The results suggest that in bronchial asthma an alteration of calcium metabolism may be important, but they also suggest that there is no simple relationship between the plasma ionized calcium concentration and acute exercise-induced bronchoconstriction.

Asthma↗
PubMed1988

Breathing pattern and eye movement density during REM sleep in humans.

Changes in the density of eye movement during rapid eye movement (REM) sleep are associated with changes in ventilation and ventilatory response in animals. Recent data in patients with chronic obstructive pulmonary disease suggest that periods of frequent eye movements may be associated with hypoxemia during REM sleep. We have therefore investigated the association between eye movements and ventilation and ventilatory pattern in 10 normal men. Expired ventilation was measured using a pneumotachograph attached to a valved face mask with a dead space of 50 ml and incorporating a peripheral CO2 leak detector. Ventilation was reduced (p less than 0.02) in all stages of sleep compared with that during wakefulness, with no difference between the level of ventilation in each sleep stage (awake, 7.18 +/- 0.43 SEM; Stage 2, 6.47 +/- 0.43; Stage 3/4, 6.45 +/- 0.52; REM sleep, 6.55 +/- 0.47 L/min). During REM sleep, eye movements (EMs) were associated with rapid shallow breathing. Dividing REM into 20-s epochs with or without EMs, EMs were associated with a raised breathing frequency (no EMs, 14.4 +/- 0.4 breaths/min; EMs, 15.8 +/- 0.5 breaths/min; p = 0.01), reduced tidal volume (0.49 +/- 0.03 L; 0.41 +/- 0.03 L; p less than 0.01), and reduced minute ventilation (6.87 +/- 0.45 L; 6.27 +/- 0.51 L; p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Steady-state concentration of cotinine as a measure of nicotine-intake by smokers.

Measurement of plasma cotinine, the major metabolite of nicotine, is usually done to determine nicotine-intake in smokers. Cotinine is used instead of nicotine because it has a much longer half-life than the mother substance and its plasma concentrations are therefore less dependent on the exact times of blood sampling. However, the linearity of the relationship between nicotine-intake and cotinine level in plasma has never been proven. Therefore cotinine was measured in 6 healthy volunteers infused over 4 days with several doses of nicotine i.v. up to 480 micrograms/kg/day. Cotinine concentrations in plasma were shown to be linearly and directly related to nicotine intake. The concentration of cotinine showed little variation during and for up to 2 h after the last dose of nicotine. Therefore, cotinine can be used as an epidemiological marker of nicotine intake if it is measured around the time of the last cigarette of the day.

Adult↗