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Biomedical subjects

C G Gallagher

Publications and source records attributed to C G Gallagher.

52 records · Page 3Linked to original sources
PubMed1990

Diagnostic value of maximal exercise tidal volume.

Though breathing pattern is frequently analyzed during clinical exercise testing, there is little information regarding its usefulness in the differential diagnosis of impaired exercise tolerance. This study tested the hypothesis that differences in peak tidal volume during exercise between patients with different cardiorespiratory diseases are related largely to differences in severity of respiratory mechanical impairment (vital capacity), not to differences in disease state. Patients with chronic obstructive pulmonary disease, restrictive lung disease, bronchial asthma, and heart disease (mitral valve disease or left ventricular dysfunction) were studied. Subjects selected had one and only one of the above diagnoses. All subjects performed maximal (symptom-limited) incremental exercise on a cycle ergometer. Multiple linear regression of all subjects (n = 30) in all four groups showed a significant correlation between VTmax and VC: VTmax = 0.55, VC -0.09 L (r = 0.827, p less than 0.0001). The VTmax/VC (x 100) was (mean +/- SD) 44 +/- 15, 54 +/- 11, 56 +/- 11, and 54 +/- 12 for the COPD, RLD, BA and HD patients respectively. There was no significant difference between any of the groups. We concluded that differences in VTmax between different patients are related largely to differences in VC (ie, differences in severity of respiratory mechanical impairment), not to differences in disease state. Measurement of VTmax or the VTmax/VC ratio has little value in the differential diagnosis of exertional dyspnea.

Aged↗
PubMed1989

Response of normal subjects to inspiratory resistive unloading.

The purpose of this study was to examine the role of the normal inspiratory resistive load in the regulation of respiratory motor output in resting conscious humans. We used a recently described device (J. Appl. Physiol. 62: 2491-2499, 1987) to make mouth pressure during inspiration positive and proportional to inspiratory flow, thus causing inspiratory resistive unloading (IRUL); the magnitude of IRUL (delta R = -3.0 cmH2O.1(-1).s) was set so as to unload most (approximately 86% of the normal inspiratory resistance. Six conscious normal humans were studied. Driving pressure (DP) was calculated according to the method of Younes et al. (J. Appl. Physiol. 51: 963-1001, 1981), which provides the equivalent of occlusion pressure at functional residual capacity throughout the breath. IRUL resulted in small but significant changes in minute ventilation (0.6 1/min) and in end-tidal CO2 concentration (-0.11%) with no significant change in tidal volume or respiratory frequency. There was a significant shortening of the duration (neural inspiratory time) of the rising phase of the DP waveform and the shape of the rising phase became more convex to the time axis. There was no change in the average rate of rise of DP or in the duration or shape of the declining phase. We conclude that 1) the normal inspiratory resistance is an important determinant of the duration and shape of the rising phase of DP and 2) the neural responses elicited by the normal inspiratory resistance are similar to those observed with added inspiratory resistive loads.

Adult↗
PubMed1989

Effect of pressure assist on ventilation and respiratory mechanics in heavy exercise.

To assess the effect of the normal respiratory resistive load on ventilation (VE) and respiratory motor output during exercise, we studied the effect of flow-proportional pressure assist (PA) (2.2 cmH2O.l-1.s) on various ventilatory parameters during progressive exercise to maximum in six healthy young men. We also measured dynamic lung compliance (Cdyn) and lung resistance (RL) and calculated the time course of respiratory muscle pressure (Pmus) during the breath in the assisted and unassisted states at a sustained exercise level corresponding to 70-80% of the subject's maximum O2 consumption. Unlike helium breathing, resistive PA had no effect on VE or any of its subdivisions partly as the result of an offsetting increase in RL (0.78 cmH2O.1-1.s) and partly to a reduction in Pmus. These results indicate that the normal resistive load does not constrain ventilation during heavy exercise. Furthermore, the increase in exercise ventilation observed with helium breathing, which is associated with much smaller degrees of resistive unloading (ca. -0.6 cmH2O.l-1.s), is likely the result of factors other than respiratory muscle unloading. The pattern of Pmus during exercise with and without unloading indicates that the use of P0.1 as an index of respiratory motor output under these conditions may result in misleading conclusions.

Adult↗
PubMed1988

Lack of radiographic evidence of interstitial pulmonary edema after maximal exercise in normal subjects.

Recent physiologic studies have indirectly suggested that interstitial pulmonary edema may develop at maximal exercise in normal humans at sea level. Therefore, we compared chest radiographs taken before and immediately after incremental exercise to maximum in 5 healthy young subjects. We looked for evidence of redistribution of pulmonary blood flow, pulmonary venous distension, loss of sharp definition of pulmonary vascular markings, hilar blurring, Kerley's A, B, or C lines, peribronchial or perivascular cuffing, widening of fissures, pleural effusion, and diffuse opacity. We also quantitated radiographic density in 6 areas of the film in each subject. There was no radiographic change to suggest an increase in lung water in any lung zone in any of the subjects. Given the documented sensitivity of chest radiography in this respect, we conclude that any increase in extravascular lung water during exercise must be trivial.

Adult↗
PubMed1987

Closing volume after inspiratory resistive loading to fatigue.

Closing volume was measured by the single breath nitrogen washout test in six normal subjects both before and after inspiratory resistive loading to fatigue. Subjects breathed through an inspiratory resistance until they could no longer maintain the required mouth pressure throughout inspiration. There was electromyographic evidence of diaphragmatic fatigue in all experiments. Closing volume (expressed as a percentage of vital capacity) after resistive loading to fatigue (10.1 +/- 1.9%) was not significantly different from that before resistive loading (10.5 +/- 1.7%). Because pulmonary edema increases closing volume, this study suggests that the very negative intrathoracic pressures generated during resistive loading do not cause pulmonary edema. Therefore, the rapid shallow breathing following inspiratory resistive loading to fatigue is not due to pulmonary edema but is probably a direct consequence of fatigue.

Adult↗
PubMed1987

Breathing pattern during maximal exercise and during submaximal exercise with hypercapnia.

During progressive exercise ventilation (VI) initially increases through increases in both tidal volume (VT) and respiratory frequency (f) but at high levels of exercise further increases in VI are almost completely due to increases in f and a VT plateau is seen. We wished to determine whether the presence of the VT plateau is due to a tachypneic influence related to very high levels of exercise or whether it represents a stereotypic response of the respiratory system at high levels of VI. We therefore compared breathing pattern in six subjects during maximal incremental exercise (ME) with that in the same subjects when similar levels of VI were obtained by a combination of submaximal exercise and hypercapnia (E/CO2). A VT plateau was seen in all ME and E/CO2 tests. There was no significant difference in the level of the VT plateau between the ME (2.93 +/- 0.17 liters) and E/CO2 (2.97 +/- 0.12 liters) tests. We conclude that the presence and level of the VT plateau during ME is not due to a tachypneic stimulus related to very high levels of exercise but is a function of the level of VI.

Adult↗
PubMed1987

Effects of expiratory resistive load on respiratory motor output in conscious humans.

We examined, in five conscious human subjects, the steady-state effects of expiratory resistive loading (ERL; R = 8 cmH2O.l-1.s) on the time course of inspiratory and postinspiratory muscle activities (IA and PIA, respectively) and ventilatory pattern during quiet breathing. Driving pressure (DP) was calculated by means of a respiratory neuromechanical model (J. Appl. Physiol. 51: 963-989, 1981) that permitted the derivation, from tidal volume and flow, of the occlusion pressure equivalent (at functional residual capacity) of respiratory neural output throughout the breath. ERL caused a prolongation of both neural inspiratory duration (12.2 +/- 6.9% SD) and expiratory duration (25.0 +/- 10.1%) and an increase in the amplitude of DP (16.5 +/- 10.2%) without any changes in the waveshape of IA and in end-expiratory level. The relative time course of PIA was not altered by ERL. Minute ventilation was depressed (-6.75 +/- 2.88%) during ERL with little change in alveolar PCO2. The results indicate that pulmonary gas exchange may be improved during ERL through increased tidal volume as well as delayed expiratory lung emptying secondary to sustained PIA.

Adult↗
PubMed1987

Chronic erosive gastritis: a clinical study.

In order to help clarify the clinical importance of chronic erosive gastritis, we describe our experience of 28 patients with this disorder who were seen over a 2-yr period. Twenty patients were male. Twenty-four patients presented with abdominal pain, for which no cause other than chronic erosive gastritis was found in 20 patients. Ten patients had pain for more than 1 yr. Three patients presented with painless vomiting. The antrum was involved in 27 patients and the body in 17 patients. There was no correlation between the number of erosions and the duration of symptoms. Double contrast barium meal was positive in nine of 21 patients. Of 19 patients treated with cimetidine, 15 improved clinically and six of eight had endoscopic improvement. The treatment of choice is unknown and controlled trials are needed. Symptoms in patients with chronic erosive gastritis appear to be due to the gastritis itself rather than to associated lesions.

Adolescent↗
PubMed1986

Atypical manifestations of pulmonary adenoid cystic carcinoma.

Pulmonary adenoid cystic carcinoma (PACC) typically arises in large airways. A patient who presented with a peripheral lung mass due to PACC is reported. She was found to have multiple pulmonary nodules due to PACC 11 years after resection of the original tumour. We emphasize that 10-15% of patients with PACC present with peripheral tumours.

Carcinoma, Adenoid Cystic↗
PubMed1986

Breathing pattern during and after maximal exercise in patients with chronic obstructive lung disease, interstitial lung disease, and cardiac disease, and in normal subjects.

Inspiratory muscle fatigue and pulmonary edema are both known to cause rapid shallow breathing. It has been suggested that exercise tolerance in patients with pulmonary disease and cardiac disease may be limited by the development of inspiratory muscle fatigue and pulmonary edema, respectively, at maximal exercise. If these hypotheses are correct, breathing pattern during recovery from maximal exercise in these patients should be rapid and shallow compared with that during exercise. This study was performed to test these hypotheses. Seven patients with chronic obstructive pulmonary disease (COPD), 8 patients with interstitial lung disease (ILD), 7 patients with cardiac disease (CD) (mitral valve disease or left ventricular dysfunction) and 8 normal (NR) subjects each performed maximal incremental exercise on a cycle ergometer. Exercise breathing pattern was compared with that during recovery by calculating the mean difference in tidal volume (at the same levels of minute ventilation) between exercise and recovery for each subject. Recovery breathing pattern was similar to that during exercise for the COPD, ILD, and NR subjects. In contrast, breathing pattern during recovery was rapid and shallow compared with that during exercise for the CD patients; recovery tidal volume was less than that during exercise for the same level of minute ventilation. The fact that rapid shallow breathing does not develop during recovery from maximal exercise in patients with COPD or ILD suggests that inspiratory muscle fatigue does not limit their exercise tolerance. The relative rapid shallow breathing during recovery from maximal exercise in patients with CD is probably due to the development of pulmonary edema at maximal exercise, but further studies are needed to confirm this.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effect of inspiratory muscle fatigue on breathing pattern.

Our aim was to determine whether inspiratory muscle fatigue changes breathing pattern and whether any changes seen occur before mechanical fatigue develops. Nine normal subjects breathed through a variable inspiratory resistance with a predetermined mouth pressure (Pm) during inspiration and a fixed ratio of inspiratory time to total breath duration. Breathing pattern after resistive breathing (recovery breathing pattern) was compared with breathing pattern at rest and during CO2 rebreathing (control breathing pattern) for each subject. Relative rapid shallow breathing was seen after mechanical fatigue and also in experiments with electromyogram evidence of diaphragmatic fatigue where Pm was maintained at the predetermined level during the period of resistive breathing. In contrast there was no significant difference between recovery and control breathing patterns when neither mechanical nor electromyogram fatigue was seen. It is suggested that breathing pattern after inspiratory muscle fatigue changes in order to minimize respiratory sensation.

Adult↗
PubMed1985

Asymptomatic giant cell arteritis.

A 71-year-old asymptomatic man was investigated because of anemia and an elevated erythrocyte sedimentation rate. Temporal artery biopsy showed that he had active giant cell arteritis. To our knowledge, this is the first report of giant cell arteritis in an asymptomatic patient. Giant cell arteritis may remain undiagnosed during life in many cases and may be an important cause of unexplained anemia in the elderly.

Aged↗
PubMed1979

Adriamycin cardiotoxicity: a survey of 1273 patients.

Valuable information was collected on the medical history and clinical course of 1273 patients entered in clinical trials with Adriamycin (ADR) carried out in 12 European cancer centers. A coded patient form was used for the data collection carried out in each center by a qualified physician following a guideline which was discussed and accepted by all of the participants. The aim of the study was to define the incidence, characteristics, and possible co-factors of the cardiomyopathy (CMP) in patients treated with combination chemotherapy regimens including ADR. The mean total dose of ADR was 268 mg/m2 (range, 15--1251 mg/m2), and 5.1% of the patients received a total dose of greater than 550 mg/m2. A "definite" ADR-related CMP was observed in 1.7% of the cases; another 3% of the cases were reported as "possible" ADR-CMP since the role played by the drug could not be clearly defined. "Definite" ADR-CMP was fatal in eight patients (0.6%) while "possible" ADR-CMP was fatal in 13 patients (1.0%). Among the possible co-factors examined, the following ones were found to be significantly associated with the occurrence of a "definite" ADR-CMP: (a) total dose of ADR; (b) vincristine when given both before and concomitantly with ADR; (c) bleomycin when given before ADR; and (d) radiotherapy to the mediastinum when given concomitantly with ADR. Furthermore, none of 182 patients receiving ADR by slow infusion developed a "definite" ADR-CMP, while 2% of the patients treated by bolus injection did so. The occurrence of a "possible" ADR-CMP was found to be significantly associated with two pre-existing pathologic conditions (electrocardiogram [ECG] abnormalities and hypertension) but not with the treatment-related co-factors for the "definite" ADR-CMP mentioned above. Other variables examined, such as sex, age, cancer type, baseline liver function, and cyclophosphamide treatment, did not seem to influence the risk of ADR-CMP. Data on ECG changes occurring during ADR treatment were also reported and their incidence was found to be strictly related to the frequency of the ECG monitoring.

Adolescent↗