Search PubMed⌕ Search

Biomedical subjects

S F Quan

Publications and source records attributed to S F Quan.

At least 73 records · Page 4Linked to original sources
PubMed1987

Prevalence of reported sleep disturbances in a general adult population and their relationship to obstructive airways diseases.

In order to determine the prevalence of reported sleep disturbances in a general adult population and the relationship of these complaints to age, gender and coexistent obstructive airways disease, 2,187 subjects in the Tucson Epidemiologic Study of Obstructive Airways Disease were surveyed in 1985 regarding their sleep symptoms. At least one symptom of disturbed sleep was present in 41.4 percent of all subjects. Women generally reported a significantly higher prevalence of both disorders of initiating and maintaining sleep (DIMS) and nightmares (NM)(p less than .001). Before age 64 years, the prevalence of complaints of excessive daytime sleepiness (EDS) among men and women were similar. However, the frequency of EDS was significantly higher in men than women after age 64 years. Prevalence of at least one sleep symptom and DIMS increased with advancing age. The prevalence of nightmares appeared to be age-related only among women, who displayed a declining prevalence with advancing age. EDS increased only after age 64 years. There was a significant relationship between DIMS and EDS with coexistent chronic bronchitis, concomitant asthma and chronic bronchitis, and emphysema, but not asthma as a solitary diagnosis. Nightmares were reported with much greater frequency among subjects with asthma, asthma and chronic bronchitis, and emphysema but not in subjects with chronic bronchitis alone. The presence of coexistent asthma and chronic bronchitis was associated with particularly high prevalence of complaints of DIMS, EDS and nightmares. We conclude that, in the general adult population, sleep disorder symptoms increase with age and usually are greater in women. Furthermore, there is an increased prevalence of sleep symptoms among adults with chronic airways obstructive disease, especially those with coexistent asthma and chronic bronchitis.

Adult↗
PubMed1987

Acute cigarette smoke exposure causes lung injury in rabbits treated with ibuprofen.

We studied lung clearance of aerosolized technetium-labeled diethylenetriamine pentaacetic acid (99mTcDTPA), plasma concentrations of 6-keto-PGF1 alpha and thromboxane B2, and pulmonary edema as indices of lung injury in rabbits exposed to cigarette smoke (CSE). Forty-six rabbits were randomly assigned to 4 groups: control sham smoke exposure (SS, N = 9), sham smoke exposure ibuprofen-pretreated (SS-I, N = 10), CSE (N = 9), sham smoke exposure ibuprofen-pretreated (SS-I, N = 10), CSE (N = 9), and CSE ibuprofen-pretreated (CSE-I, N = 19). Ibuprofen (cyclooxygenase eicosanoid inhibitor) was administered as a single daily intramuscular injection (25 mg/kg) for 7 days before the experiment. Cigarette or sham smoke was delivered by syringe in a series of 5, 10, 20, and 30 tidal volume breaths with a 15-min counting period between each subset of breaths to determine 99mTcDTPA biological half-life (T1/2). In the ibuprofen pretreated group, CSE caused significant decreases in 99mTcDTPA T1/2 and dynamic lung compliance. Furthermore, these changes in lung function were accompanied by severe injury to type I alveolar cell epithelium, pulmonary edema, and frequently death of the rabbits. These findings suggest that inhibition of the cyclooxygenase pathway before CSE exacerbates lung injury in rabbits.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Intravenous platelet activating factor does not affect lung epithelial permeability.

Administration of platelet activating factor has been shown to produce lung edema in several species including the rabbit. To determine if platelet activating factor increases lung alveolar epithelial permeability, we studied the effect of intravenous platelet activating factor administration on clearance of 99mTc-DTPA from the lung of the rabbit. Intravenous platelet activating factor produced marked hemodynamic and cellular responses but did not increase the clearance of 99mTc-DTPA from lung to blood. We conclude that although platelet activating factor can induce lung edema in the rabbit, it does not produce an acute increase in alveolar epithelial permeability.

Animals↗
PubMed1986

Variability of pulmonary responsiveness to aerosolized histamine in normal rabbits.

Considerable between-subject variability in pulmonary responsiveness to histamine has been reported in normal human subjects, dogs, guinea pigs, and rhesus monkeys, but rabbits have not been studied. We determined the between- and within-rabbit variability of pulmonary histamine responsiveness in 34 anesthetized and mechanically ventilated New Zealand White rabbits. In 30 rabbits, 5 breaths of aerosolized histamine were delivered in 9 increasing concentrations ranging from 0.01 to 100 mg/ml. Eleven of 30 rabbits were rechallenged with histamine on 1-4 additional occasions over a 3-week period. In the remaining 4 rabbits, 9 doses of distilled H2O were aerosolized to determine the degree of spontaneous variability in measurements of lung resistance (RL) and dynamic lung compliance (Cdyn). We defined an increase in RL of greater than 50% of baseline (TD50RL) and a decrease in Cdyn of greater than 25% of baseline (TD25Cdyn) as being significant based on observations in these 4 rabbits. These limits exceeded the 99.9 percentile of spontaneous variability in RL and Cdyn. Pulmonary responsiveness to histamine varied widely, with a greater than 10,000-fold range in TD50RL and a 1,000-fold range in TD25Cdyn between the most and least sensitive rabbits. The variability of this responsiveness was log-normally distributed. It was not correlated with age, sex, or baseline RL and Cdyn. In contrast, within-rabbit responses to histamine challenge were quite reproducible. Five of 30 rabbits were killed at the conclusion of their histamine challenges for pathologic examination of their lungs. No evidence of airway inflammation was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1985

Pulmonary lymphangioleiomyomatosis: quantitative analysis of lesions producing airflow limitation.

The lungs of three patients dying of lymphangioleiomyomatosis (LAM), which in two of the patients was associated with tuberous sclerosis, were studied to characterize better the sites of airflow limitation in this condition. Quantitative studies showed that small airways were narrowed and collapsed because of the surrounding emphysema, but few airways contained excess smooth muscle. These findings suggest that the airspace lesions are more important than muscular proliferation in small airways in producing airflow limitation. In the two patients who had LAM with tuberous sclerosis, sex steroid assays were negative. Pleurodesis controlled pleural effusions in all three patients but may have contributed to reductions in lung volume.

Adult↗
PubMed1985

Polysomnography scoring for sleep apnea. Use of a sampling method.

The all-night polysomnogram is used to assess the severity of sleep apnea by the quantitative analysis of a number of respiratory and sleep parameters. Because precise scoring of these parameters is a time-consuming process, we studied the effect of scoring varying percentages of polysomnograms on the accuracy of estimating sleep apnea severity. Twenty adult all-night polysomnograms with apnea-hypopnea (AH) indexes ranging from 1.0 to 67.8 were scored in the following manner: every 30-s epoch (100% scoring), every other epoch (50% scoring), every fourth epoch (25% scoring), every sixth epoch (16.7% scoring), every eighth epoch (12.5% scoring), and every tenth epoch (10% scoring). Each method was then compared with 100% scoring. For each parameter we established criteria for classifying studies as having a mild, moderate, or severe degree of abnormality. The number of studies correctly categorized for the following parameters was: (1) AH index, 20/20 for 50 and 25% scoring, 19/20 for 16.7 and 10% scoring, and 18/20 for 12.5% scoring; (2) AH time, 20/20 for 50, 25, and 16.7% scoring, 17/20 for 12.5% scoring, and 18/20 for 10% scoring; (3) mean AH duration, 20/20 for 50, 25, and 12.5% scoring, 18/20 for 16.7% scoring, and 15/20 for 10% scoring; (4) mean event percent O2 saturation, 20/20 for 50 and 25% scoring, 18/20 for 16.7 and 12.5% scoring, and 17/20 for 10% scoring; (5) longest AH, 19/20 for 50% scoring, 18/20 for 25% scoring, and 15/20 or less for 16.7, 12.5, and 10% scoring; (6) lowest percent O2 saturation, 19/20 for 50% scoring, 17/20 for 25% scoring, and 15/20 or less for 16.7, 12.5, and 10% scoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Acute cigarette smoke exposure increases alveolar permeability in rabbits.

We measured lung clearance of aerosolized technetium-labeled diethylenetriamine pentaacetic acid (99mTcDTPA) as an index of alveolar epithelial permeability in rabbits exposed to cigarette smoke. Eighteen rabbits were randomly assigned to 3 equal-size groups: control, all smoke exposure (ASE), and limited smoke exposure (LSE). Cigarette or sham smoke was delivered by syringe in a series of 5, 10, 20, and 30 tidal volume breaths with a 20-min counting period between each subset of breaths to determine 99mTcDTPA biologic half-life (T1/2). Mean T1/2 minimum (i.e., the smallest T1/2 observed) was significantly lower (p less than 0.05) for ASE and LSE rabbits than by control rabbits. We observed a significant difference at 20 and 30 breath exposures between the control and ASE group mean values (% baseline) for T1/2, arterial blood pressure, and peak airway pressure. A combination of light and electron microscopy showed focal alveolar edema and hemorrhage in the ASE and LSE groups but no alveolar-capillary membrane damage. In summary, acute cigarette smoke exposure increases alveolar permeability as measured by 99mTcDTPA clearance, but there was no detectable ultrastructural alteration of the alveolar-capillary membrane.

Animals↗
PubMed1984

Suppression of ventricular ectopy with intravenous metoprolol in patients with chronic obstructive pulmonary disease.

Intravenous metoprolol, 0.2 mg/kg, was given to 11 patients with stable, partially reversible chronic obstructive pulmonary disease (COPD) and frequent ventricular ectopic depolarizations (VEDs). The frequency of VEDs during 8 h of continuous ECG recording was reduced from a mean of 214/h to 86/h (p less than .001). Four/11 patients had a greater than 90% reduction in VEDs. There were no adverse clinical effects during the period of drug administration. However, metoprolol produced small declines of 14% in the forced expiratory volume in 1 sec (FEB1) and 21% in the forced expiratory flow rate between 25% and 75% of the forced vital capacity (FVC) (FEF25-75). These data suggest that iv metoprolol is effective in reducing the frequency of VEDs in patients with COPD, although the extent of reduction in VEDs shows considerable interindividual variation. Metoprolol can be administered iv without inducing clinical bronchospasm in most patients.

Aged↗
PubMed1984

Airway movement in dogs during high-frequency jet ventilation.

Cine tantalum bronchograms were recorded from 7 pentobarbital-anesthetized dogs during spontaneous ventilation (SV), high-frequency jet ventilation (HFJV) at 3 frequencies, and intermittent positive-pressure ventilation (IPPV) at 3 combinations of tidal volume (VT) and rate. During SV and the 3 IPPV conditions, the percent inspiratory increase in the diameter of airways greater than 3 mm was the same as in airways less than 3 mm. With HFJV, the percent increase in the diameter of airways greater than 3 mm was twice that of smaller airways. Increases in airway diameter are proportional to transmural, and hence intraluminal airway pressure. These data, therefore, indicate that the contribution of intraluminal pressure changes to intrapulmonary gas transport in small airways during HFJV is less than with either SV or IPPV, and that mechanisms responsible for intrapulmonary gas transport in small conducting airways during HFJV are different than those associated with either SV or IPPV.

Air Movements↗
PubMed1984

Airway pressure as a measure of gas exchange during high-frequency jet ventilation.

Airway pressure during high-frequency jet ventilation (HFJV) reflects safety, ventilator performance, and gas exchange. The value of airway pressure as a monitoring and control variable for predicting the effectiveness of gas exchange was examined in 2 studies using healthy dogs. In the first study, HFJV was delivered to the airway via an extra lumen in the wall of an endotracheal tube, at a frequency of 150 cycle/min and 30% inspiratory time. Airway pressures (peak, mean, trough) were measured at various locations, from 5 cm below to 30 cm above the jet port. Pressures measured above the jet were misleading, but the proper measurement distance below the jet remains uncertain. The second study used the same ventilator settings but varied the airway pressure difference between peak and end-expiratory pressures (2, 4, or 6 cm H2O), and either the mean airway pressure (6 or 10 cm H2O) or the positive end-expiratory pressure (0, 5, 10, or 15 cm H2O). The airway pressure difference correlated strongly with efficiency of gas exchange for both CO2 elimination and oxygenation. Mean and end-expiratory pressures showed little influence over moderate ranges, but use of 15 cm H2O of PEEP decreased efficiency of both CO2 elimination and oxygenation, presumably due to increased dead space because of lung overdistension. We conclude that the airway pressure difference, measured as far distal in the airway as is safe and practical, can be useful for monitoring and controlling HFJV.

Animals↗
PubMed1984

Comparison of high-frequency jet ventilation with conventional mechanical ventilation in saline-lavaged rabbits.

A surfactant-depletion lung-injury model was produced in 37 New Zealand white rabbits by saline lavage. During the next 2 to 3 h, rabbits were ventilated with conventional mechanical ventilation (CMV, group 1), high-frequency jet ventilation (HFJV, group 2), or CMV for 1 h followed by HFJV for 2 h (CMV/HFJV, group 3). Survival until planned termination of the protocol was 56%, 77%, and 63% in groups 1, 2 and 3, respectively. Causes of early demise were usually pneumothorax or metabolic acidosis. There were no statistically significant differences among the groups with respect to survival, incidence of pneumothorax or metabolic acidosis. Arterial oxygenation was more efficient with HFJV (group 2) (P[A-a]O2 = 372 +/- 51 torr [mean +/- SE] at 2 h) than with CMV (group 1) (P[A-a]O2 = 512 +/- 18 torr at 2 h, p less than .01). Furthermore, oxygen gas exchange in 3 of 5 group 3 rabbits improved after institution of HFJV. In contrast to previous findings with high-frequency oscillation (HFO), there were no qualitative histologic differences between lungs ventilated with HFJV vs. CMV. Thus, although HFJV produced more efficient gas exchange in this model, it did not improve pulmonary pathology. HFO may be preferable to HFJV in infant respiratory distress syndrome.

Animals↗
PubMed1983

Failure of acute hypoxia to alter pulmonary prostaglandin metabolism in dogs.

We studied the effects of acute hypoxia (Fi02 = 0.09-0.11, 20 min.) on transpulmonary plasma prostaglandin (PG) concentrations in ten anesthetized, paralyzed, artificially ventilated dogs. Concentrations of 6-keto-PGF1 alpha, TxB2, PGE2, PGF2 alpha, and 13,14-dihydro-15-keto-PGF2 alpha were measured from the pulmonary artery and abdominal aorta using radioimmunoassay. In an additional six dogs, the effects of arachidonic acid (AA) infusions (100 mcg/kg/min) during normoxia and acute hypoxia were determined. Compared to normoxic conditions, acute hypoxia increased pulmonary artery pressure (p less than 0.05), decreased both the arterial oxygen tension (PaO2) and the alveolar-to-arterial oxygen tension gradient (A-aDO2) (p less than 0.05), but did not affect transpulmonary plasma PG concentrations. AA infusions significantly (p less than 0.05) increased 6-keto-PGF1 alpha independent of FiO2. Acute hypoxia failed to elicit a pulmonary pressor response in the AA-treated animals although PaO2 and A-aDO2 decreased (p less than 0.05). These data in healthy dogs suggest that (1) acute hypoxia does not alter net pulmonary PG metabolism, (2) prostacyclin synthesis is stimulated by increased plasma AA concentrations and (3) this effect may block normal pressor responses to hypoxic stimuli.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

High frequency ventilation applications in the OR.

High frequency ventilation provides effective gas exchange at frequencies between 60 and 2,400 min-1. It can be potentially useful in the operating room for bronchoscopy, laryngoscopy, airway surgery, general surgery, and microscopic neurosurgery.

Airway Resistance↗
PubMed1983

Diffuse epithelial pleural mesothelioma presenting as a solitary lung mass.

We report the occurrence of a malignant pleural epithelial mesothelioma which presented radiographically and at surgery as a localized solitary mass, but was found microscopically to involve grossly normal pleura. Clinically diffuse mesothelioma recurred 19 months later. Localized malignant mesothelioma has been associated with the same poor prognosis as the diffuse form and, as suggested by this case, may represent an early phase of diffuse disease.

Diagnosis, Differential↗