Biomedical subjects

C A Vaz Fragoso

Publications and source records attributed to C A Vaz Fragoso.

4 recordsLinked to original sources

PubMed1995

Establishing a physiological basis to multiple sclerosis-related fatigue: a case report.

OBJECTIVE: Although fatigue is a common debilitating complaint in multiple sclerosis (MS), its relationship to the cardiopulmonary exercise response has yet to be defined. DESIGN: A patient with MS manifested primarily by profound fatigue undergoes complete pulmonary function testing and a maximal incremental cycle ergometry study with gas exchange measurements and determination of ejection fractions. SETTING: Outpatient, community hospital pulmonary function laboratory. RESULTS: The patient is found to have respiratory muscle weakness and a severely depressed exercise performance. The latter was associated with an early anaerobic threshold but a normal central cardiovascular response (radionuclide ventriculography), implying problems in peripheral O2 distribution/utilization. The respiratory muscle involvement, although substantial, was nonlimiting to the exercise performance. CONCLUSIONS: Despite its central neuropathophysiology, MS as it relates to fatigue may be associated with an abnormal peripheral exercise response, namely, problems in peripheral O2 utilization. Such a concept could prove invaluable as it would provide a physiological basis for defining the severity and therapy of "MS fatigue."

Adult↗

PubMed1993

Review of the clinical efficacy of theophylline in the treatment of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is associated with significant morbidity and mortality. Therapeutic options are few and are often limited in efficacy. Theophylline is one option, but its use appears to have recently reached a threshold point of deemphasis. Given the consequences of further diminishing the available treatment of COPD, a reappraisal of theophylline's role is imperative. This report reviews the clinical efficacy of theophylline in managing patients with COPD. Special consideration is given to theophylline's effects on pulmonary function (i.e., bronchodilation, exercise capacity, and gas exchange), dyspnea, mucociliary clearance, respiratory muscle performance, cardiovascular function, and neuroinspiratory drive. Despite the lack of standardization in study design and methodology among the studies evaluating theophylline, the conflicting results, and the questions that remain to be answered, evidence indicates that theophylline can provide meaningful therapeutic benefit to patients with COPD. In addition, several studies in patients with COPD have shown that theophylline and inhaled beta-agonists interact in an additive fashion, and the combination therapy results in additional objective and subjective improvement over that achieved by either preparation alone.

Animals↗

PubMed1993

The tidal volume response to incremental exercise in COPD.

Patients with severe COPD often exhibit a ventilatory limit to exercise. This is associated with a shallow breathing pattern when compared with normal control subjects. It is unclear, however, what factors affect differences in breathing patterns within this patient population. To further investigate the tidal volume (VT) response to exercise in severe COPD, nine patients were recruited to undergo a maximal incremental exercise test. Pulmonary function tests, collection of expired gases, and continuous pulse oximetry were performed. As a group, the results were as follows (mean +/- SD): The FEV1 was 31 +/- 7 percent of predicted, the FRC was 143 +/- 18 percent of predicted, and the DCO was 47 +/- 15 percent of predicted. Exercise testing showed an oxygen consumption at peak exercise of only 44 +/- 9 percent predicted, a dyspnea index of 101 +/- 19 percent predicted, a heart rate at peak exercise of 75 +/- 12 percent predicted, a tidal volume at peak exercise (PKVT) of 1.23 +/- .35, a respiratory rate at peak exercise (PKfb) of 26 +/- 6, and an oxygen saturation at peak exercise (PKO2sat) of 96 +/- 4 percent. An anaerobic threshold (AT) occurred in seven of the nine patients at a mean of 31 +/- 8 percent predicted maximal oxygen consumption. Regression analysis showed the PKVT to be inversely correlated with the FEV1 (r = -0.76; p = 0.01) and the PKfb (r = -0.85; p = 0.003), while positively correlating with the FRC (r = +0.80; p = 0.01) and the PKO2sat (r = +0.69; p = 0.04). Additionally, there was a trend for the PKVT to be inversely related with the AT (r = -0.72; p = 0.06). In COPD, the more severe the obstruction and hyperinflation, the larger the VT response to exercise. This may serve to avoid a deleterious increase in autoPEEP by promoting a lengthening of the expiratory time. Furthermore, given the association of an earlier AT and a higher PKO2sat with a larger PKVT, this would suggest that such a response may minimize the effects of dead space and/or autoPEEP on O2 delivery (early AT).

Anaerobic Threshold↗

PubMed1992

Improvement in exercise capacity after nocturnal positive pressure ventilation and tracheostomy in a postpoliomyelitis patient.

Progressive neuromuscular symptoms years after recovery from acute paralytic poliomyelitis have been termed the PPS. We describe a 52-year-old man who contracted poliomyelitis at age 9 years who fully recovered and 33 years later developed progressive dyspnea. Neurologic evaluation revealed bilateral paralysis of the vocal cords, generalized weakness, and accentuated mouth occlusion pressure and ventilatory responses to hypercapnic, hyperoxic breathing. An EMG and muscle biopsy showed changes consistent with acute and chronic denervation. Cardiopulmonary exercise evaluation demonstrated a pulmonary mechanical limit with excessive ventilation relative to CO2 output. Tracheostomy and nocturnal positive pressure ventilation resulted in increased respiratory muscle strength, normalization of ventilatory drive and marked improvement in exercise capacity.

Dyspnea↗