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Biomedical subjects

R W Light

Publications and source records attributed to R W Light.

At least 127 records · Page 7Linked to original sources
PubMed1993

Influence of atelectasis on pulmonary function after coronary artery bypass grafting.

The purpose of this study was to determine the influence of atelectasis on pulmonary function 6 days following coronary artery bypass grafting (CABG). After 6 days, 30 patients had normal chest radiographs, 38 had atelectasis, and 57 had pleural changes. In 11 patients, atelectasis only was observed in the radiograph, and in 27 it was in combination with pleural changes. The decrease in FVC and FEV1 in the patients with atelectasis was 33.4 and 33.5 percent in the SVG group and 34.8 and 34.3 percent in the IMA group, while in those patients with a normal radiograph, the decrements were 26.3 and 26.9 percent in SVG group and 26.1 and 26.9 percent in IMA group, respectively. Thus, patients with atelectasis on the 6th postoperative day have a larger decrement in pulmonary function post CABG than the patients with normal chest radiograph and this reduction reflects a higher degree of thoracic trauma.

Coronary Artery Bypass↗
PubMed1993

The incidence of pleural effusion in a well-defined region. Epidemiologic study in central Bohemia.

Pleural effusion may complicate various diseases. To facilitate the differential diagnosis of pleural effusion, the authors conducted an epidemiologic study of incidence and etiology of different types of pleural effusions in a well-defined region in central Bohemia. During a 1-year period, the authors worked with the general practitioners and other physicians from the local hospital to identify patients with pleural effusion either while the patient was alive or at autopsy. During this period, 142 individuals (93 living and 49 at autopsy) with pleural effusion were identified among a population of 44,000 (incidence = 0.32 percent). The most common etiologies of the effusions were congestive heart failure (65, 46 percent), malignant effusions (31, 22 percent), parapneumonic effusions (24, 17 percent), and pulmonary emboli (8, 5.6 percent). Other etiologies for the effusions included pulmonary hemothorax (6), intra-abdominal processes (4), uremia (2), myxedema (1), and rheumatoid pleuritis (1). We conclude that pleural effusions are relatively common and if these figures are extrapolated to the United States and Czechoslovakia respectively, one could expect at least 800,000 cases in the United States and 48,000 in Czechoslovakia annually. Over 90 percent of the pleural effusions will be due to congestive heart failure, malignancy, pneumonia, or pulmonary emboli.

Aged↗
PubMed1993

Effectiveness of bleomycin in comparison to tetracycline as pleural sclerosing agent in rabbits.

The two agents most commonly used for producing a pleurodesis are tetracycline and bleomycin. Tetracycline is no longer available due to more stringent requirements on the manufacturing process. The objective of this project was to determine whether bleomycin is an effective sclerosant in an experimental model in rabbits. The following medications were instilled intrapleurally in anesthetized male rabbits: tetracycline, 35 mg/kg, or bleomycin, 1.5 or 3.0 IU/kg diluted to a total volume of 1 ml with bacteriostatic saline solution. Twenty-eight days after the instillation, the animals were killed, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of bleomycin was ineffective in creating pleural fibrosis, either grossly or microscopically. The mean degree of gross pleurodesis in the six rabbits who received tetracycline was 2.7 +/- 1.5 (scale 0 to 4), while that in the rabbits who received the highest dose of bleomycin was 0.0 +/- 0.0. Based on this study, we recommend that bleomycin not be used as a pleural sclerosant in patients with nonneoplastic pleural disease, eg, those with pneumothorax, congestive heart failure or cirrhosis, and pleural effusion.

Analysis of Variance↗
PubMed1992

Pleural diseases.

In the United States, approximately one million patients each year develop a pleural effusion. Pleural effusions have classically been divided into transudative and exudative pleural effusions. A transudative pleural effusion occurs when the systemic factors influencing pleural fluid formation and reabsorption are altered so that pleural fluid accumulates; an exudative pleural effusion occurs when the local factors influencing pleural fluid formation and reabsorption are altered, allowing accumulation of pleural fluid. The leading causes of transudative pleural effusions are left ventricular failure and cirrhosis with ascites. The leading causes of exudative pleural effusions are pneumonia, malignancy, and pulmonary embolization. Transudative pleural effusions can be differentiated from exudative pleural effusions by measurement of the pleural fluid protein and lactic dehydrogenase (LDH) levels. The ratio of the pleural fluid protein to the serum protein is less than 0.5, the ratio of the pleural fluid LDH to the serum LDH is less than 0.6, and the absolute value of the pleural fluid LDH level is less than two thirds of the upper normal limit for serum with transudative pleural effusions while at least one of these criteria is not met with exudative effusions. Most patients who have a pleural effusion with congestive heart failure have left ventricular failure. It is believed that the transudation of the pulmonary interstitial fluid across the visceral pleura overwhelms the capacity of the lymphatics to remove the fluid. Most patients with cirrhosis who have a pleural effusion also have ascites. It is also believed that the pleural effusions form when fluid moves directly from the peritoneal cavity into the pleural cavity through pores in the diaphragm. Approximately 40% of patients with pneumonia will have a pleural effusion. If these patients have a significant amount of pleural fluid, a diagnostic thoracentesis should be performed. Chest tubes should be inserted if the pleural fluid is gross pus, if the Gram stain of the pleural fluid is positive, if the pleural fluid glucose level is below 40 mg/dl, or if the pleural fluid pH level is less than 7.00. If drainage with the chest tubes is unsatisfactory, either streptokinase or urokinase should be injected intrapleurally. If drainage is still unsatisfactory, a decortication should be considered. The three leading malignancies that have an associated pleural effusion are breast carcinoma, lung carcinoma, lymphomas and leukemias. The diagnosis of pleural malignancy is made most commonly with pleural fluid cytology; in recent years immunohistochemical tests have proved invaluable in differentiating benign from malignant pleural effusions.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1992

Iatrogenic pneumothorax: etiology and morbidity. Results of a Department of Veterans Affairs Cooperative Study.

The purpose of this study was to delineate the etiological factors for iatrogenic pneumothorax in the era of increased use of invasive procedures and to determine its impact on morbidity. Between 1983 and 1987 the Department of Veterans Affairs conducted a cooperative study at 13 medical centers to assess the utility of the intrapleural instillation of tetracycline for the prevention of recurrent pneumothorax. Since all patients with any type of pneumothorax were screened at each medical center, it was decided to collect data on all the iatrogenic pneumothoraces during that period. During the study period, the number of reported iatrogenic pneumothoraces were 538. Because of incomplete data, 3 iatrogenic pneumothoraces reported from one center were excluded. The leading causes of iatrogenic pneumothorax were transthoracic needle aspiration (128), subclavicular needle stick (119), thoracentesis (106), transbronchial biopsy (54), pleural biopsy (45) and positive pressure ventilation (38). Most patients required treatment for 4-7 days; however, hospitalization was prolonged due to this treatment in only 8% of patients, presumably because of their underlying disease which required long hospitalization. Patients with underlying chronic obstructive pulmonary disease required significantly longer duration of treatment than those without. We conclude that in our patient population, the three leading causes of iatrogenic pneumothorax are transthoracic needle aspiration, subclavicular needle stick and thoracentesis. Hospitalization is prolonged in only a small percentage of the patients who required treatment for the iatrogenic pneumothorax.

Adult↗
PubMed1992

Effect of ethanol on the arousal response to airway occlusion during sleep in normal subjects.

The effect of ethanol on the arousal response to airway occlusion during non-rapid eye movement sleep was studied in normal male subjects by testing the response to the occlusion of a face mask covering the nose and mouth on a control (C) and an ethanol (E) ingestion (2 ml/kg of 50% vodka) night in random order. In part A, five subjects breathed room air while in part B another five subjects breathed a mixture of air and oxygen adjusted to maintain a baseline sleeping SaO2 of 98%. In both parts, the time to arousal (TTA) was significantly longer on E nights. The TTA (mean +/- SEM) in part A on C versus E nights was 14.6 +/- 1.9 versus 20.6 +/- 1.4 s in stage 2 and 19.9 +/- 1.9 versus 29.2 +/- 1.8 in stage 3/4 (p less than 0.01). The corresponding values in part B were 22.2 +/- 3.6 versus 39.9 +/- 8.4 in stage 2 and 32.1 +/- 4.1 versus 63.7 +/- 9.6 in stage 3/4 (p less than 0.01). In part B, the maximum deflections in airway pressure were measured at a supraglottic location during airway occlusion to reflect the degree of inspiratory effort. The maximum airway suction pressure preceding arousal was significantly higher on E nights. Conversely, the rate of increase in inspiratory effort (maximum pressure) during occlusion was decreased by E. We conclude that moderate ethanol ingestion prolongs the time to arousal following airway occlusion by increasing the threshold of inspiratory effort associated with arousal and by decreasing the rate of increase in the magnitude of inspiratory efforts.

Adult↗
PubMed1992

Inspiratory muscle work of breathing during flow-by, demand-flow, and continuous-flow systems in patients with chronic obstructive pulmonary disease.

The effect of flow-by continuous positive airway pressure (CPAP) in comparison with continuous-flow (CF) CPAP on inspiratory muscle work of breathing (WI) in intubated patients is not known. We hypothesized that WI during flow-by CPAP would be comparable with that during CF CPAP. In nine intubated male patients recovering from acute respiratory failure related to chronic obstructive pulmonary disease, we compared the effects of flow-by, demand-flow, and CF CPAP on WI. We also evaluated the extent to which the addition of 5 cm H2O of pressure support to demand-flow CPAP (DF-PS5) decreases WI. At CPAP levels of zero and 8 cm H2O, flow-by, demand-flow, DF-PS5 were applied in random order followed by CF CPAP for 15 min each. WI (expressed as Joules per liter and Joules per minute), maximal airway pressure drop during inspiration (delta Paw), total lung resistance (RL), lung compliance (CL), and ventilatory variables were measured. At CPAP of zero cm H2O, WI with flow-by was comparable with CF CPAP, and significantly less than with demand-flow CPAP. At both CPAP of zero and 8 cm H2O, the addition of 5 cm H2O PS to demand-flow CPAP reduced WI significantly to a level comparable with that of flow-by CPAP. At both CPAP levels, delta Paw was the largest, with demand-flow CPAP. RL and CL were not significantly different between the different CPAP systems. We conclude that WI with flow-by CPAP is comparable with that with CF CPAP, and significantly less than with demand-flow CPAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Effect of hyperoxia on the arousal response to airway occlusion during sleep in normal subjects.

The effect of hyperoxia on the arousal response to airway occlusion during non-rapid eye movement (NREM) sleep was studied in six normal male subjects with a mean age (+/- SD) of 23.5 +/- 8.7 yr by testing the response to the occlusion of a face mask covering the nose and mouth. Occlusion trials while the subjects breathed room air (room air condition) were alternated with trials in which subjects breathed a mixture of room air and oxygen adjusted to maintain a sleeping baseline arterial oxygen saturation of 98% (hyperoxic condition). The time to arousal (mean +/- SEM) was significantly longer during oxygen administration (4.1 +/- 4.5 versus 28.9 +/- 4.6 s; p < 0.002). The maximal deflections in airway pressure were measured at a supraglottic location during airway occlusion to reflect the degree of inspiratory effort. The maximal airway suction pressure preceding arousal did not differ between the room air (27.4 +/- 5.4 cm H2O) and hyperoxic conditions (26.6 +/- 5.9 cm H2O). Conversely, the rate of increase in inspiratory effort (maximal pressure) during occlusion was decreased by oxygen administration. We conclude that hyperoxia prolongs the time to arousal after airway occlusion by decreasing the rate of increase in the magnitude of inspiratory efforts, but it does not change the arousal threshold.

Adolescent↗
PubMed1992

The effect of triazolam on the arousal response to airway occlusion during sleep in normal subjects.

The purpose of this study was to assess the effect of triazolam (0.25 mg) on the arousal response to airway occlusion during nonrapid eye movement sleep in normal subjects. Six male subjects (mean age +/- SD, 28.1 +/- 7.1 yr) had their arousal response tested by occluding a mask covering the nose with the mouth sealed. After an adaptation night, subjects were studied on two consecutive nights. They ingested triazolam (0.25 mg) or placebo one-half hour before bedtime in a randomized double-blind crossover manner. Mask occlusion was performed 1 to 4 h after triazolam/placebo ingestion while the subjects breathed a mixture of air and oxygen adjusted to produce an arterial oxygen saturation of 98%. The maximal deflections in airway pressure were measured at a supraglottic location during airway occlusion to reflect the degree of inspiratory effort. The time to arousal (mean +/- SEM) was significantly longer on triazolam nights (32.0 +/- 5.2 versus 22.6 +/- 3.2 s, p < 0.01). The maximal airway suction pressure preceding arousal was higher on triazolam nights (26.5 +/- 2.0 cm H2O versus 20.0 +/- 1.2 cm H2O, p < 0.02). Conversely, the rate of increase in inspiratory effort (maximal pressure) during occlusion was not decreased by triazolam. We conclude that triazolam prolongs the time to arousal following airway occlusion by increasing the arousal threshold.

Adult↗
PubMed1992

Postoperative pleural changes after coronary revascularization. Comparison between saphenous vein and internal mammary artery grafting.

Coronary artery bypass grafting (CABG) is commonly performed with a saphenous vein graft (SVG) and/or an internal mammary artery graft (IMA). We hypothesized that there would be a higher incidence of pleural changes after CABG in patients who underwent IMA grafting because pleurotomy is usually performed. In the present study, the pre and the 6th postoperative day chest roentgenograms of 122 patients who received CABG were reviewed. The incidence of effusion in the patients who received only SVG was 43 percent (23/54) and did not differ significantly (p greater than 0.05) from the incidence in the patients who also had IMA 41 percent (28/68). Almost all of the patients (43/51) had unilateral left-sided pleural effusions. Most of the effusions were small and did not require treatment. The incidence of effusion was not higher in patients with enlargement of their cardiac silhouette or atelectasis and was not related to the presence of chest tubes. The incidence of pleural thickening was higher in the IMA group (49 percent) than in the SVG group (31 percent) but the difference did not achieve statistical significance (p greater than 0.05). We conclude that there is a high (approximately 40 percent) incidence of small effusions and thickening after CABG. The incidence of pleural effusion and pleural thickening do not appear to be influenced by the type of surgery (IMA vs SVG). We speculate that the effusions are due to pericardial inflammation.

Coronary Artery Bypass↗
PubMed1992

Effect of inhaled furosemide on the bronchial response to lysine-aspirin inhalation in asthmatic subjects.

It has been demonstrated recently that inhaled furosemide inhibits bronchoconstriction induced by cold air, physical exercise, various antigens, and metabisulfite. The goal of the present study was to determine if the inhalation of furosemide would inhibit the bronchoconstriction resulting from the inhalation of lysine-aspirin in aspirin-sensitive asthmatics. Six female subjects with known hypersensitivity to aspirin participated in this crossover study comparing 20 mg of inhaled furosemide and placebo. The volunteers inhaled increasing concentrations of lysine-aspirin after the inhalation of furosemide or placebo. The geometric mean provocative dose causing a 20 percent decrease in the FEV1 (PD20) after the inhalation of placebo was 30.4 mg/ml and the PD20 was equal or below 90 mg/ml in all patients. In contrast, the FEV1 did not decrease by 20 percent in any of the patients pretreated with furosemide when the inhaled concentration was increased to 360 mg/ml. From this study, we conclude that the administration of furosemide blocks the bronchospasm induced by the inhalation of lysine-aspirin in aspirin-sensitive asthmatics.

Administration, Inhalation↗
PubMed1992

Relationship between pleural changes after myocardial revascularization and pulmonary mechanics.

It is known that coronary artery bypass grafting (CABG) results in impairment of postoperative pulmonary function. There is also a high incidence of pleural changes (pleural effusion or pleural thickening) after CABG. We hypothesized that those patients with pleural changes in the postoperative period would have a greater decrease in pulmonary function test (PFTs) results. The present study reports the results of 110 male patients who underwent CABG. The chest films and the PFT results obtained preoperatively and on the sixth postoperative day were reviewed. The relationship between pleural changes and PFTs was analyzed in patients who received saphenous vein graft alone (SVG group: 50 patients) or in combination with internal mammary artery grafting (IMA group: 60 patients). In the IMA group, the patients who had pleural changes had significantly greater decreases in their pulmonary function than did the patients without pleural changes. The decrease in the FVC, TLC and FEV1 in the patients with pleural effusions (37.6, 27.8 and 36.8 percent) was similar to that in patients with pleural thickening (34.6, 28.3 and 35.0 percent) and both were significantly greater (p < 0.05) than the changes in the patients with a normal radiograph (26.1, 17.6 and 26.9 percent). In the SVG group, the presence of pleural changes was not significantly related to the decrement in pulmonary function. The values of RV, FRC, Cst, and blood gases were not affected in the SVG or IMA group by the presence of pleural changes. We conclude that the presence of pleural changes on the chest radiograph is associated with a larger decrement of pulmonary function after CABG in the IMA group. This larger decrease probably reflects added thoracic trauma and is not due to the presence of pleural changes per se.

Coronary Artery Bypass↗
PubMed1992

Arterial blood gases after coronary artery bypass surgery.

Coronary artery bypass graft (CABG) surgery adversely affects arterial blood gas (ABG) determinations. The purposes of this study were to assess serial changes in ABGs following bypass surgery and identify factors that may influence these changes. Room air ABGs were obtained preoperatively and on days 1, 2, 4, 6, and 8 postoperatively on 125 patients undergoing bypass surgery. Fifty-five patients (saphenous vein grafting [SVG] group) had only SVG grafting while 70 (internal mammary artery [IMA] group) received one (60 patients) or two (10 patients) IMA grafts in addition to the SVG grafts and were subjected to pleurotomy. The mean preoperative values (+/- SD) were as follows: PaO2, 75.1 +/- 7.7 mm Hg, P(A-a)O2, 20.9 +/- 7.5 mm Hg; PaCO2, 33.6 +/- 4.1 mm Hg; pH, 7.43 +/- 0.04; hemoglobin, 14.8 +/- 1.4 g/dl; and hematocrit, 44.2 +/- 3.9 percent. There was a large decrease in the PaO2 postoperatively. The nadir for the PaO2 (55.7 +/- 6.6 mm Hg) occurred on the second postoperative day. Eight days postoperatively, there were still significant abnormalities; the PaO2 was 65.7 +/- 7.3 mm Hg, the P(A-a)O2 was 33.2 +/- 8.8 mm Hg; the hemoglobin was 10.5 +/- 1.4 g/dl; and the hematocrit was 31.7 +/- 4.0 percent. The decrease in the PaO2 was particularly noteworthy given the large decrease in the hemoglobin and hematocrit. The changes in the PaO2 were not significantly correlated with the age, number of grafts, pump time, length of anesthesia, or endotracheal intubation or smoking history. Immediately postoperatively, changes were similar in both groups (p > 0.05); on the second postoperative day, the PaO2 had decreased 26.9 percent in the SVG group and 25.5 percent in the IMA group. However, the postoperative abnormalities resolved more slowly in the IMA group (p < 0.05). These observations suggest that the additional trauma to the lungs and chest wall in the IMA group (pleurotomy, the placing of pleural drains, etc) will result in a longer recovery time in the IMA group than in SVG group.

Carbon Dioxide↗
PubMed1991

Effect of theophylline on sleep and sleep-disordered breathing in patients with chronic obstructive pulmonary disease.

To investigate the effect of theophylline on sleep and sleep-disordered breathing in patients with chronic obstructive pulmonary disease (COPD), we studied 12 male nonhypercapnic subjects with a mean +/- SEM age of 62.8 +/- 2.5 yr and a FEV1 of 1.36 +/- 0.11 L using a randomized double-blind crossover protocol. Sustained-action theophylline (250 mg three times or four times a day) or placebo was administered for 2 days, and the alternate drug was administered on the following 2 days. Sleep studies were performed on Nights 2 and 4 with spirometry at 9:00P.M. and 7:00A.M. Two puffs of metaproterenol or albuterol were administered at 10:00P.M. on both study nights. A theophylline level, drawn at bedtime (10:00 to 11:00P.M.), was 14.2 +/- 0.78 micrograms/ml on the theophylline nights and less than 2 on placebo nights. The morning FEV1 was significantly better during theophylline administration (1.27 +/- 0.12 versus 1.00 +/- 0.11 L, p less than 0.001). The mean arterial oxygen saturation (SaO2) and transcutaneous carbon dioxide pressure (PCO2) were also better during NREM sleep on theophylline nights. Neither the mean SaO2 and transcutaneous PCO2 during REM sleep nor the apnea plus hypopnea index (events per hour of sleep) differed between placebo and theophylline nights. Theophylline administration did not impair the amount or architecture of sleep as neither total sleep time nor the fraction of time spent in Stages 1, 2, and 3/4 and REM differed between the two regimens. The number of arousals per hour of sleep was slightly less on theophylline nights (19.9 +/- 1.7 versus 24.9 +/- 2.7, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Arousal↗
PubMed1991

Pressure-time product during continuous positive airway pressure, pressure support ventilation, and T-piece during weaning from mechanical ventilation.

The objective of this study was to compare the effects of continuous positive airway pressure (CPAP), pressure support ventilation (PS), and T-piece on the pressure-time product (PTP) during weaning from mechanical ventilation. The PTP is an estimate of the metabolic work or oxygen consumption of the respiratory muscles. We studied 10 intubated patients recovering from acute respiratory failure of various etiologies. A modified continuous flow (flow-by) CPAP of 0 and 5 cm H2O (CPAP-0 and CPAP-5, respectively), PS of 5 cm H2O (PS-5), and T-piece were applied in random order for 30 min each. In the last 5 min of the 30-min periods, we measured the esophageal pressure and transdiaphragmatic pressure-time products--PTP(es) and PTP(di), cm H2O.s/min, respectively-multiplied by respiratory frequency. Breathing pattern, total lung resistance (RL), quasi-static lung compliance (CL), intrinsic positive end-expiratory pressure (PEEPi), end-expiratory transpulmonary pressure (Ptpexp), arterial blood gases, blood pressure, and heart rate were also measured. In comparison to T-piece, CPAP-5 decreased PTP(es) 40% (p less than 0.01) and PTP(di) 43% (p less than 0.02), whereas PS-5 decreased PTP(es) 34% (p less than 0.01) and PTP(di) 38% (p less than 0.05). The decrease in PTP(es) with CPAP-5 was associated with a significant reduction in RL, and to a less extent in PEEPi relative to airway pressure. The contribution of the decrease in PEEPi to the reduction in PTP(es) amounted to 36%. With PS-5, respiratory system mechanics and PEEPi were not significantly different compared with T-piece. With CPAP-0, PTP tended to be lower than with T-piece.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of high- and low-carbohydrate meals on maximum exercise performance in chronic airflow obstruction.

The purpose of this study was to compare the effects of isocaloric liquid meals with high fat (55 percent) and low carbohydrate (28 percent) content (Pulmocare) to meals with low fat (30 percent) and high carbohydrate (53 percent) content (Ensureplus) on exercise performance in subjects with chronic airflow obstruction (CAO). Twelve stable subjects with CAO (FEV1 = 1.30 +/- 0.47 L) underwent incremental symptom-limited exercise tests 90 minutes following the ingestion of 920 calories of EnsurePlus HN (E), 920 calories of Pulmocare (P), or a noncaloric placebo (C). Tests were performed on three days, in a double-blind randomized fashion. Expired gases were collected continuously and analyzed every 30 seconds. The mean maximal work load after E (81 +/- 24 W) was significantly less than that after P (88 +/- 21 W) or C (88 +/- 24 W). The mean ventilation at exhaustion was similar after E (48 +/- 13 L/min), P (51 +/- 11 L/min), and C (49 +/- 10 L/min). In comparison to C, six of the 12 individuals had a decreased work load following E, while only one had a decreased maximal tolerated work load following P. The results of this study suggest that meals with a higher fat and lower carbohydrate content may be less likely to impair work performance of patients with CAO in the absorptive phase than meals with a lower fat and higher carbohydrate content. These findings may have clinical significance to patients with CAO who complain of postprandial exertional dyspnea.

Aged↗
PubMed1991

Conversion of COPD patients from multiple to single dose theophylline. Serum levels and symptom comparison.

The objective of the present study was to determine if patients with COPD who were taking Theo-Dur bid or tid (total dose 400 to 900 mg per day) could be safely switched to Uni-Dur, 800 mg given qd at bedtime. Twenty-eight patients were enrolled in the study, and 23 completed the study. The mean daily dose of theophylline prior to the study was 828 mg, while the mean dose after three weeks of Uni-Dur therapy was 783 mg. The mean serum theophylline level 10.5 +/- 3.6h after the last Theo-Dur dose was 10.5 mg/L. After three weeks of Uni-Dur therapy, the mean theophylline level at 8:00 AM was 14.6 mg/L, while the mean theophylline level at 8:00 PM was 9.9 mg/L. This latter level did not differ significantly from that obtained at the start of the study 10.5 +/- 3.6 h after the last dose of Theo-Dur. After three weeks of Uni-Dur therapy, the peak expiratory flow rate, the FEV1, and the FVC were not significantly changed from those at the initial evaluation. Twenty-one of the 23 patients ended up receiving 800 mg Uni-Dur qd. From this study, we conclude that once daily theophylline dosing with Uni-Dur compared with bid or tid dosing with Theo-Dur produces similar theophylline levels and pulmonary function, and most COPD patients who are taking 400 to 900 mg Theo-Dur daily can be managed with 800 mg Uni-Dur once daily at bedtime.

Aged↗