PubMed Health⌕ Search

Biomedical subjects

R M Rogers

Publications and source records attributed to R M Rogers.

At least 55 records · Page 3Linked to original sources
PubMed1989

Ventilation and breathing pattern during progressive hypercapnia and hypoxia after human heart-lung transplantation.

The effects of human pulmonary denervation on the ventilatory responses to progressive hyperoxic hypercapnia and isocapnic hypoxia as well as the effect on resting breathing pattern were evaluated in nine female heart-lung transplant (H-LT) recipients. The results were compared to those obtained from 10 normal women of comparable age and stature. Testing was performed 2 to 37 months after H-LT (median, 7.5 months). Cardiac function was normal in all H-LT recipients. None of the patients had spirometric evidence of airway obstruction, while six had a restrictive pattern with forced vital capacities less than 80% of predicted values. Resting minute ventilation (VE), tidal volume (VT), and ventilatory drive (VT/TI) in the H-LT recipients were not significantly different from those of the normal subjects. Inspiratory time (TI), however, was significantly shorter in the H-LT patients (1.64 +/- 0.2 versus 2.09 +/- 0.13 s, p = 0.035), and resting breathing frequency (F) tended to be greater in the H-LT recipients (16.27 +/- 2.04 versus 12.82 +/- 0.53 breaths/min, p = 0.052). The overall ventilatory response to hypercapnia was reduced after H-LT (0.91 +/- 0.17 versus 1.5 +/- 0.27 L/min/mm Hg CO2, p less than 0.043), as was the F response (0.2 +/- 0.09 versus 0.65 +/- 0.13 breaths/min/mm Hg CO2, p less than 0.01). The VT and VT/TI responses to hypercapnia did not differ between the H-LT recipients and normal subjects. There were no significant differences between the two groups with respect to the responses to progressive hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Breathing during wakefulness and sleep after human heart-lung transplantation.

To study the effects of pulmonary denervation on breathing during sleep, sleep studies were conducted on seven heart-lung transplant recipients (H-LT) and a comparable number of sex-matched normal subjects of similar age. Four of the H-LT patients had a restrictive pattern on spirometry. The time since transplantation ranged from 45 to 1,102 days. There were no significant differences between the groups with respect to total sleep time or distribution of sleep stages. There were no significant differences between the H-LT recipients and normal subjects with respect to baseline awake oxyhemoglobin saturation (SaO2) or the nadirs of SaO2 during REM and non-REM sleep, the absolute number and frequency (number per hour of sleep) of apneas, hypopneas, desaturation events, both over the whole night of study or separately during non-REM and REM sleep. Across wakefulness and all sleep stages, the H-LT patients tended to have shorter total respiratory cycle times (Ttot) (p = 0.052) and more rapid breathing frequency (F) than the normal subjects. This was associated with significantly shorter inspiratory times (Tl) (p less than 0.001) and smaller duty cycles (Tl/Ttot) (p less than 0.005) in the H-LT recipients. During non-REM and REM sleep, F tended to be higher in the H-LT recipients with pulmonary restriction than in the nonrestricted patients. There were no significant differences between the H-LT recipients and the normal subjects with regard to the periodicity of breathing, either in terms of timing parameters or breath amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Oxygen consumption of the respiratory muscles in normal and in malnourished patients with chronic obstructive pulmonary disease.

Patients with severe chronic obstructive pulmonary disease (COPD) commonly experience weight loss. An increased energy expenditure for respiration might explain the increased caloric requirements and weight loss seen in this patient population. We measured the oxygen cost of augmenting ventilation (O2 cost) using an open circuit technique with dead-space stimulation of ventilation in nine normally nourished (greater than 90% ideal body weight) and in 10 malnourished (less than 90% ideal body weight) patients with COPD as well as in seven normal control subjects. O2 cost was significantly elevated in the malnourished patients with COPD (4.28 +/- 0.98 ml O2/L ventilation) relative to the normally nourished group (2.61 +/- 1.07) and the normal control subjects (1.23 +/- 0.51) (p less than 0.001). The measured resting energy expenditure (REEmeas) was also increased compared with predicted values (REEpred) in the malnourished population (REEmeas/REEpred = 94.57 +/- 6.21% for control subjects, 105.5 +/- 19.66% for normally nourished patients with COPD, and 119.4 +/- 11.69% for malnourished patients with COPD) (p less than 0.005). The malnourished population was characterized by a greater degree of hyperinflation (RV/TLC = 0.55 +/- 0.09 for normally nourished versus 0.69 +/- 0.06 for malnourished patients) and inspiratory muscle weakness (PImax = 51 +/- 16.5 for the normally nourished and 34 +/- 12.2 for the malnourished population). We conclude that malnourished patients with COPD are characterized by a relative increase in resting energy requirements and, specifically, increased energy requirements for augmenting ventilation. This increase in energy requirements may result from the increased mechanical work load associated with severe COPD and/or a reduced ventilatory muscle efficiency.

Aged↗
PubMed1988

DLco in COPD.

Explore the source record for details and available documents.

Humans↗
PubMed1987

Prolonged spontaneous remission in a patient with untreated pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis is a relatively rare, diffuse lung disease for which whole lung bronchopulmonary lavage is an effective treatment. The possibility of spontaneous remission also exists, but few actual cases have been described. This report describes a 56-year-old woman in whom pulmonary alveolar proteinosis was diagnosed 18 years earlier and who had a prolonged spontaneous remission before presenting with disabling symptoms. The possibility of prolonged spontaneous remission, although unusual, needs to be kept in mind when therapeutic decisions are to be made in patients with pulmonary alveolar proteinosis.

Female↗
PubMed1987

Effects of positive end-expiratory pressure on hepatic blood flow and performance.

Positive end-expiratory pressure (PEEP) may impair extrapulmonary organ function. However, the effects of PEEP on the liver are unclear. We tested the hypothesis that at a constant cardiac output (CO), PEEP does not induce changes in hepatic blood flow (QL) and parenchymal performance. In splenectomized, close-chested canine preparations (group I, n = 6), QL was derived as hepatic outflow using electromagnetic flow probes (QLemf), and hepatic performance was defined by extraction and clearance of indocyanine green (ICG). In a noninvasive model (group II, n = 7), the effects of PEEP on hepatic performance alone were similarly analyzed. Measurements were taken during intermittent positive-pressure ventilation (IPPV1), after addition of 10 cmH2O PEEP to IPPV (PEEP1), during continued PEEP but after return of CO to IPPV1 levels by intravascular volume infusions (PEEP2), and after removal of both PEEP and excess blood volume (IPPV2). Phasic inspiratory decreases in QLemf present during positive-pressure ventilation were not increased during either PEEP1 or PEEP2. Mean QLemf decreased proportionately with CO during PEEP1 (P less than 0.05), but was restored to IPPV1 levels in a parallel fashion with CO during PEEP2. The ICG pharmacokinetic responses to PEEP were complex, with differential effects on extraction and clearance. Despite this, hepatic performance was not imparied in either group. we conclude that global QL reductions during PEEP are proportional to PEEP-induced decreases in CO and are preventable by returning CO to pre-PEEP levels by intravascular volume infusions. However, covarying changes in blood volume and hepatic outflow resistance may independently modulate hepatic function.

Animals↗
PubMed1987

Augmentation of rat alveolar macrophage migration by surfactant protein.

Since the alveolar macrophage (AM) resides in an environment made unique by the presence of pulmonary surfactant, we studied the effect of constituents of pulmonary surfactant on the migration of these cells in vitro. Whole pulmonary surfactant, surfactant phospholipids, and a delipidated preparation of surfactant consisting mainly of protein were tested for their effect on AM migration. Migration was measured in multiwell chemotaxis chambers with endotoxin-activated rat serum (EARS) as the stimulus. The delipidated surfactant material (DSM) markedly augmented the migration of rat AM. Enhancement was seen only when migration was stimulated with EARS. Augmentation of stimulated migration occurred over a wide range of protein concentrations in DSM (3.5 to 56 micrograms/ml) in a dose-dependent fashion. Rat AM that were preincubated with DSM and then tested in the chemotaxis assay without DSM showed increased migration towards EARS when compared with AM preincubated in buffer alone. The enhancing effect of DSM on AM migration was significantly diminished by heating the DSM and by enzymatic digestion with trypsin, suggesting that the active constituent in DSM was protein. Thus, it appears that proteins isolated from pulmonary surfactant augment the stimulated migration of AM via an interaction between the protein and the macrophage. Although the identity of these proteins remains to be elucidated, it is unlikely they include albumin since purified rat serum albumin in concentrations comparable to that of protein in DSM did not enhance the stimulated migration of AM. These results represent further confirmation that constituents of surfactant modulate the clearance function of AM in vitro. Thus, it is likely that surfactant plays a role in lung defense mediated by AM.

Animals↗
PubMed1986

Nutritional intervention in malnourished patients with emphysema.

We have previously reported the association of significant malnutrition with pulmonary emphysema and noted that the degree of malnutrition correlated with some measures of pulmonary function. The purpose of this study was to examine the energy requirements of malnourished patients with emphysema and acute effects of nutritional repletion on indices of pulmonary function and nutrition. We studied 6 malnourished patients with emphysema during a 3-wk admission to a clinical research unit. Initially, patients were allowed access to standard food sources ad libitum. Subsequently, if caloric goals were not met, nutritional supplementation was given orally. All patients receiving the ad libitum diet ingested calories in excess of their maintenance energy requirements. All patients increased their body weight (p less than 0.001) and percent ideal body weight (p less than 0.001). Anthropometric nutritional parameters showed a small but significant improvement (p less than 0.05). Although there was no significant change in spirometric results, lung volumes or DLCO after 3 wk maximal inspiratory mouth and transdiaphragmatic pressures increased (p less than 0.005). Peripheral skeletal muscle strength as measured by handgrip also improved (p less than 0.001). We conclude that inability to ingest an adequate number of calories was not the cause of weight loss in these patients. We also found that when given sufficient calories in excess of their needs, patients gain weight. Weight gain and improvement in anthropometric measurements are accompanied by significant improvement in ventilatory and peripheral muscle strength.

Aged↗
PubMed1986

Patient compliance with nasal CPAP therapy for sleep apnea.

Continuous positive airway pressure via the nasal route (nasal CPAP) is effective in reducing the frequency of occlusive and mixed patterns of sleep apnea. Little is known about long-term patient compliance with this therapeutic modality, however. In order to evaluate this, questionnaires were mailed to 24 sleep apnea patients who had received a nasal CPAP system for nightly use. Patients were requested not to sign the questionnaire. At the time of mailing, the patients had possessed their nasal CPAP equipment for 10.3 +/- 8 months (mean +/- SD). Twenty patients (83 percent) responded to the questionnaire. Sixteen responders used nasal CPAP during all nightly sleep time, and two used it for all but one and 2.5 hours of nightly sleep time, respectively. One individual used it on alternate nights, and one patient did not use it all. Thus, 17 of 20 (85 percent) responders were compliant. Including information about the four nonresponders, obtained by means other than questionnaire, 18 of 24 (75 percent) patients were compliant with therapy. All but two patients were obese at the time sleep apnea was diagnosed. Only 50 percent of questionnaire responders reported weight loss after receiving nasal CPAP, and these individuals were frequent nasal CPAP users. The most common complaints were mask discomfort (14 responders) and nasal dryness and congestion (13 responders). We conclude that long-term home nasal CPAP is a viable therapy that is conscientiously applied and well-tolerated by most sleep apnea patients.

Adolescent↗
PubMed1986

Nutritional aspects of chronic obstructive pulmonary disease.

Nutritional status is an important factor in certain patients with chronic obstructive pulmonary disease (COPD). This article reviews the prevalence and effects of weight loss as well as potential strategies for nutritional repletion in COPD.

Animal Nutritional Physiological Phenomena↗
PubMed1985

Bronchiectasis masquerading as pulmonary embolus.

The diagnosis of bronchiectasis usually suggests a patient with a productive cough and shortness of breath. This report describes the case history of an otherwise healthy 43-year-old man who presented with repetitive episodes of pleuritic pain that led to several extensive, invasive evaluations in search of a pulmonary embolus. Only after a carefully taken history did the patient admit to an intermittent chronic cough, which suggested the diagnosis of bronchiectasis. This diagnosis was ultimately confirmed by bronchography. This report suggests that patients with bronchiectasis may present with unusual clinical manifestations, and that the correct diagnosis may be missed unless physicians are aware that "old" diseases may present in "new" ways.

Acute Disease↗
PubMed1985

Prolonged expiratory phase in sleep apnea. A unifying hypothesis.

The mechanisms responsible for the various sleep apnea patterns have not been elucidated. In 5 hypersomnolent patients, we analyzed 613 events that would have been labeled mixed and central apneas had usual recording sensitivity been employed. Recording air flow at high sensitivity revealed that in most of these events expiratory flow was present throughout most of the prolonged period during which there was no inspiratory effort. In 378 events, resumption of inspiratory effort was unaccompanied by air flow (occluded events), whereas in 144 events resumption of inspiratory effort was accompanied by inspiratory air flow (not-occluded events). In another 91 events, expiratory air flow ceased during the interval between inspiratory efforts and then recommenced unaccompanied by expiratory effort suggesting airway closure and reopening. Because expiratory air flow is present during a substantial portion of the prolonged interval between inspiratory efforts seen in our sleeping patients, we conclude that "apneas" should be defined relative to absence of inspiratory air flow. In addition, it appears that the initial portion of "mixed," and at least some "central apneas," are associated with increased expiratory upper airway resistance.

Adult↗
PubMed1985

Effect of mechanical ventilator mode on tendency towards respiratory alkalosis.

The question whether assist-control ventilation (A/C) results in more frequent or more severe respiratory alkalosis than intermittent mandatory ventilation (IMV) is often raised. We prospectively compared the respiratory rates and arterial blood tensions of 18 critically ill patients with respiratory failure of diverse causes who were mechanically ventilated for 1 h with each of these ventilatory modes. Each patient served as his own control. We found that after 1 h of IMV the average pH was 7.42 +/- 0.2 (mean +/- SEM), after 1 h of A/C the pH was 7.45 +/- 0.01 (p less than 0.005), the average PaCO2 during IMV was 40.7 +/- 1.8, the average PaCO2 during A/C was 37.9 +/- 1.6 (p less than 0.001), the average respiratory rate during IMV was 21 +/- 2.0, and the average respiratory rate during A/C was 15 +/- 2.0 (p less than 0.001). One patient became alkalemic (pH 7.55) during A/C. These pH and PaCO2 changes were not associated with any adverse clinical sequelae. We conclude that the responsible physician should be guided by factors other than control of pH in choosing the mode of mechanical ventilation for most patients.

Adult↗