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Biomedical subjects

C F Donner

Publications and source records attributed to C F Donner.

At least 109 records · Page 6Linked to original sources
PubMed1992

Can long-term oxygen therapy improve exercise capacity and prognosis?

The lack of studies as to whether the correction of desaturations during exercise can play a role in improving survival still leaves many problems usually met in the common practice open. (1) Why prescribe long-term oxygen therapy (LTOT) on exercise? Up to now, supplemental oxygen during exercise seems more an approach to the 'dyspnea symptom' than a pivotal component of a comprehensive strategy for long-term management of severe chronic airway obstruction. (2) Who needs LTOT on exercise? It seems reasonable to correct desaturations if this leads to a substantial improvement in exercise tolerance. As to the method of clinical assessment, pulse oximetry can be used for measuring desaturation between rest and exercise, although absolute values are not reliable. (3) How to prescribe LTOT on exercise? In practice, the O2 flow able to prevent desaturation on exercise, restoring an SaO2 greater than 90%, is the usual prescription criterion after an appropriate testing able to demonstrate a significant increase in exercise tolerance and conducted comparing the results breathing air with those on O2, the patient being unaware of the inhaled mixture. (4) How to administrate LTOT on exercise? A portable source is usually employed to allow the greatest possible independency. A reservoir nasal cannula can halve the oxygen wastage and is less expensive than a pulse demand valve. In patients needing 24-hour oxygen therapy the transtracheal catheter is being used more and more at present.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗
PubMed1992

Survival in COPD patients with a daytime PaO2 greater than 60 mm Hg with and without nocturnal oxyhemoglobin desaturation.

There have been few studies examining the relationship between NOD and mortality in patients with COPD and none examining this relationship in those patients with a daytime PaO2 greater than 60 mm Hg. Is NOD related to early death, and if so, should nocturnal supplemental oxygen be considered as therapy for altering survival? We examined survival in 169 COPD subjects. Two definitions were used to classify subjects as NOD and non-NOD, one considering episodic desaturation associated mainly with REM sleep (definition 1) and one considering greater than 30 percent of time in bed spent below an SaO2 of 90 percent (definition 2) to be significant. Survival corrected for age was significantly better in non-NOD subjects. However, when stratified for supplemental oxygen use, survival remained better only in subjects separated by definition 1. There was a trend toward increased survival in 35 oxygen-treated vs 38 non-oxygen-treated NOD subjects (definition 1), but this difference was not statistically significant.

Circadian Rhythm↗
PubMed1992

Ventilatory and metabolic changes as a result of exercise training in COPD patients.

Patients with COPD feel better and are able to sustain a given level of activity longer after a program of exercise training, but the underlying physiologic mechanisms have not been completely elucidated. Since the physical performance of patients with COPD is limited mainly by pathophysiologic derangements of the ventilatory system, the exercise performance can be ameliorated by increasing the level of ventilation that they can sustain or by reducing the ventilatory requirement for a given level of activity. Almost all studies have yielded negative results in patients with COPD in terms of exercise training having the ability to improve VEmax. The only way to reduce the ventilatory requirement is to reduce CO2 output. Lower levels of lactate result in less nonmetabolic CO2 produced by bicarbonate buffering and this is the likely mechanism responsible for a lower ventilatory requirement for work rates above the pretraining anaerobic threshold. We specifically wished to determine whether a program of intensity, frequency, and duration known capable of producing a physiologic training effect in healthy subjects would do so in patients with COPD. Further, we sought to determine whether exercise training at a work rate associated with lactic acidosis is more effective in inducing a training effect in patients with COPD than a work rate not associated with lactic acidosis. Nineteen patients with COPD were selected and performed an incremental test as well as 2 square wave tests at a low and a high work rate. Identical tests were performed after an 8-week program of cycle ergometer training either for 45 min/day at a high work rate or for a proportionally longer time at a low work rate. For the high work rate training group, identical work rates engendered less lactate (4.5 vs 7.2 mEq/L) and less VE (48 vs 55 L/min) after training; the low work rate training group had significantly less lactate and VE decrease (p less than 0.01). Further, in the first group, there was an increase in exercise tolerance averaging 71% in the high constant work rate test. There was a good correlation (r = 0.73, p less than 0.005) between the decrease in blood lactate and the decrease in ventilation. The major findings of this study are that patients with COPD who experience lactic acidosis during exercise can achieve physiologic training responses from a program of endurance training and that training work rates engendering high levels of blood lactate are more effective than work rates eliciting low lactate levels.

Acidosis, Lactic↗
PubMed1992

Does chronic lung failure lead to cognitive failure?

This study seeks to find out whether impaired cognition is associated with Chronic Obstructive Pulmonary Disease (COPD). Two experiments have been carried out to address two aspects of selective attention: a focused attention paradigm with a random and a facilitated condition and a divided attention paradigm with and without interference. Twenty-eight COPD patients and 28 matched healthy controls took part in both experiments. Reaction time (RT) was the variable considered. COPD patients had slower RTs than controls, however facilitation and interference had the same effect on both groups. No correlation was found between neuropsychological measures and lung failure indices. A threshold model in the lung-failure/brain-failure trade-off is envisaged.

Adult↗
PubMed1992

Semi-quantitative X-ray microanalysis of bronchoalveolar lavage samples from silica-exposed and nonexposed subjects.

To evaluate the possibility of quantifying alveolar dust burden in conditions of exposure to silica, four groups of subjects were submitted to bronchoalveolar lavage (BAL): 10 healthy control subjects and 39 patients affected by diffuse interstitial lung disease (DILD) never exposed to dust, 23 silicotic patients and 12 chronic bronchitis patients with a history of occupational exposure to silica dust. Five to ten million BAL recovered cells were analysed with an energy-dispersive X-ray microanalysis (EDXA) system to determine the silicon content, expressed in a semi-quantitative way as silicon to sulphur (Si/S) ratio. The results were independent of smoking habit. The Si/S median values (interquartile range in brackets) for the four groups were 0.53 (0.5-0.65), 0.60 (0.41-0.8), 1.23 (1.06-1.39), 1.31 (1.11-1.97), respectively. Silicotics and simply exposed individuals did not show a significant discrepancy, but they were both significantly different in comparison with normal and DILD patients without history of exposure (p less than 0.001). 14.3% false negative cases were found, and 4.1% false positive cases (none among normal subjects). We did not see any significant relationships between the amount of silicon and the duration of exposure or the degree of chest X-ray involvement. A study of cytocentrifuge slides from the same subjects by polarizing light microscopy revealed a lower sensitivity (34% false negative cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchitis↗
PubMed1991

Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstructive lung disease.

Though exercise training is part of most pulmonary rehabilitation programs, whether there is a physiologic basis for increased exercise tolerance is unclear. We sought to determine whether patients with chronic obstructive pulmonary disease (COPD) are capable of obtaining a physiologic training effect, as manifested by a reduction in blood lactate and ventilation (VE) at a given level of exercise. We also sought to determine whether training work rate determines the size of the training effect. Nineteen participants with COPD of predominantly moderate severity in an inpatient rehabilitation program performed two cycle ergometer exercise tests at a low and a high work rate for 15 min or to tolerance and also an incremental exercise test to tolerance. Arterial blood was sampled for blood gas and lactate analyses. Identical tests were performed before and after 5-day-per-week cycle ergometer training for 8 wk either for 45 min/day at a high work rate (average, 71 W) or for a proportionally longer time at a low work rate (average, 30 W). Average FEV1 was 56 +/- 12% predicted and did not change with training. Peak exercise lactate (average, 6.5 mEq/L) was not correlated with FEV1. For the high work rate training group, identical work rates engendered less lactate (4.5 versus 7.2 mEq/L) and less VE (48 versus 55 L/min) after training; the low work rate training group had significantly less lactate and VE decrease (p less than 0.01). Further, endurance time for the high constant work rate increased 73% in the high work rate training group but only 9% in the low work rate training group. At identical work rates, VE decrease average 2.5 L/min per mEq/L decrease in lactate (r = 0.75). We conclude that most COPD subjects studied increased blood lactate at low work rates. Many of these patients were able to achieve a physiologic training effect. Though total work was the same, training at a high work rate was more effective than was training at a low work rate. The lower VE requirement to perform exercise was in proportion to the lower lactate level, but the VE decrease for a given decrease in lactate was smaller than that seen in normal subjects (7.2 L/min/mEq/L), apparently because patients with COPD fall to hyperventilate in response to lactic acidosis (PaCO2 does not drop). These findings provide a physiologic rationale for exercise training of patients with COPD.

Acidosis, Lactic↗
PubMed1991

Acid phosphatase (EC 3.1.3.2) activity in alveolar macrophages from patients with active sarcoidosis.

Five main acid phosphatase (AcP) zones have been recognized and studied by polyacrylamide-gel electrophoresis. Band 5 represents the only tartrate-resistant form and is present in bone osteoclasts and in human alveolar macrophages (AMs). This study was carried out to quantify the presence of total and tartrate-resistant AcP (TrAcP) in AMs from bronchoalveolar lavage (BAL) of 11 patients with first stage sarcoidosis and in 13 nonsmokers and 16 smokers serving as control healthy subjects. The AMs from smokers showed an increase in total AcP activity (115.9 +/- 77.8 mU/10(6)); on the contrary, macrophages of patients with sarcoidosis revealed a consistent decrease in total AcP (27.8 +/- 7.0 mU/10(6)) and particularly the TrAcP subtype (14.8 +/- 3.7 mU/10(6)) in comparison with control nonsmokers (AcP = 42.2 +/- 18.9 mU/10(6) [p = NS]; TrAcP = 35.1 +/- 15.1 mU/10(6) [p less than 0.005]). The decrease in TrAcP activity was inversely correlated with the lymphocyte number (r = -0.75; p less than 0.01), lymphocyte percentage (r = -0.62; p less than 0.05), and CD4/CD8 ratio (r = -0.61; p less than 0.05). After six months of follow-up, the cytologic BAL picture returned completely to normal in five patients with full spontaneous regression of sarcoidosis; and also at the same time, normal values of TrAcP activity were restored. Since TrAcP activity can be easily detected, its possible use, along with the lymphocyte count and CD4/CD8 ratio, as a prognostic indicator of the clinical course of sarcoidosis deserves further investigation.

Acid Phosphatase↗
PubMed1991

Protective effect and duration of action of formoterol aerosol on exercise-induced asthma.

The short-term protective effect on exercise-induced asthma (EIA) and the duration of action of formoterol, given by metered dose aerosol at a dose of 24 micrograms, were compared with salbutamol (200 micrograms) and placebo in twelve asthmatic EIA-positive patients in a double-blind, placebo-controlled, three period cross-over study. On each treatment day the patients were given one of the drugs or placebo and two exercise tests were performed at the second and at the eighth hour after dosing. Using a standard procedure, exercise was performed by treadmill in well-controlled environmental conditions. In the first test at 2 h a significant difference relative to placebo (p less than 0.001) at each incremental time after exercise (i.e. 5, 10, 15, 20, 30 min) was obtained with both formoterol and salbutamol, without any significant difference between formoterol and salbutamol. After the eighth hour test formoterol still protected against EIA in comparison to both salbutamol and placebo. The effect of salbutamol at this time was not different from placebo. No adverse effects were reported in any treatment group. Formoterol has a long duration of action in protecting against EIA that persisted for eight hours, removing the need to dose with beta 2-agonist before every exercise.

Adrenergic beta-Agonists↗
PubMed1991

[Indications and results of exercise rehabilitation in patients with chronic obstructive lung diseases].

The aim of physical exercise retraining in patients with chronic obstructive lung disease undergoing rehabilitation is to increase the anaerobic work capacity with a rise in VO2 max. Exercise programmes must take into account the duration, frequency and intensity of exercise. In these patients, numerous factors limit physical exercise, including (a) decreased ventilatory capacity and respiratory muscles fatigue; (b) decreased efficacy of the pulmonary gas exchanges; (c) altered pulmonary vascular bed with altered cardiovascular response. The most widely used training methods are walking (or running), practising on a conveyor belt and using an ergometric bicycle. The last named seems to be the best method to evaluate the physiological effects of exercise or for experimental studies. Patients who are fit to participate in a retraining programme must be in a stable period and have a stable pharmacological regimen; they must be subjected to a preliminary exercise test in order to evaluate the main physiological parameters and to obtain information on their tolerance to exercise, on the presence of lactic acidosis and on the degree of hypoxaemia and hypercapnia. In the absence of contra-indications, a training programme can be set up with 30 to 45 minutes of exercise per day at least 3 to 5 times a week during 5 to 8 weeks, with a load amounting to 50-60% of VO2 max. Two questions remain to be answered: (a) is oxygen therapy useful during retraining; (b) what effect has training on survival?

Acidosis, Lactic↗
PubMed1990

Long-term oxygen therapy in patients with diagnoses other than COPD.

Long-term O2 prescription in chronic non-COPD hypoxic lung disease is, at present, based largely on physiological rather than on clinical studies. Controlled long-term studies in this field are difficult to perform. The cooperation of many centers is necessary to obtain a large and homogeneous population as the incidence of these diseases is significantly lower than COPD.

Aged↗