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R W Light

Publications and source records attributed to R W Light.

At least 91 records · Page 5Linked to original sources
PubMed1996

Serial pleural fluid analysis in a new experimental model of empyema.

Prior attempts to create an animal model of empyema by direct inoculation of bacteria alone into the pleural space have been unsuccessful. The animals either died of overwhelming sepsis or cleared the infection from the pleural space without development of an empyema. We hypothesized that injection of bacteria with a nutrient agar into the pleural space would allow the bacteria to remain in the pleural space for an extended time period, permitting an empyema to develop. The bacterium Pasteurella multocida in brain heart infusion (BHI) agar was injected into the right hemithorax of 12 New Zealand white male rabbits. Our preliminary studies showed that the animals died in less than 7 days if they were not given parenteral antibiotics. For this reason, the rabbits were given penicillin, 200,000 U, IM, every 24 h starting 24 h after bacterial injection. Pleural fluid was sampled by thoracentesis at 12, 24, 48, 72, and 96 h after bacterial injection. Pleural fluid pH, glucose, lactate dehydrogenase (LDH), leukocyte count, and Gram's stain and culture (in one half of the animals) were obtained at each time point. Pleural biopsy specimens were obtained at autopsy after 96 h. The mean pleural fluid pH reached a nadir of 7.01 at 24 h and remained less than 7.1 throughout the experiment. The mean pleural fluid glucose level reached a nadir of 10 mg/dL at 24 h. The mean pleural fluid LDH peaked at 21,000 IU/L at 24 h and the mean pleural fluid leukocyte count peaked at 12 h with a value of 67,000 cells per cubic millimeter. Gram's stains revealed organisms and cultures were positive for growth in all animals at 12 and 24 h. Some animals had positive Gram's stains and growth on cultures up to 72 h after bacterial injection. At autopsy, all rabbits injected with bacteria had gross pus in the right pleural space and had developed a thick pleural peel. Microscopic specimens of the pleura revealed large numbers of leukocytes (primarily polymorphonuclear lymphocytes) with invasion of the adjacent lung and chest wall. In conclusion, this model more closely mimics the empyema that occurs in humans, relative to previous animal models. This model appears appropriate for additional randomized studies in which different methods for the treatment of empyema can be evaluated.

Agar↗
PubMed1996

Effect of 30 mg of morphine alone or with promethazine or prochlorperazine on the exercise capacity of patients with COPD.

OBJECTIVE: We have shown that the administration of 0.8 mg/kg of morphine (M) to patients with COPD resulted in a 20% increase in the maximum oxygen consumption (Vo2max), but was associated with significant drowsiness and euphoria. The objective of the present study was to ascertain whether lower doses of M alone or in combination with prochlorperazine (PC) or promethazine (P) could elicit significant increases in exercise tolerance. DESIGN: The exercise capacity, psychological status, and reaction times were assessed before and 60 min after the patients received placebo (PLAC), 30 mg M orally, 30 mg M plus 10 mg PC (M-PC), or 30 mg M plus 25 mg P (M-P) in a randomized double-blind crossover study. In a secondary study, nine patients were tested on three separate days before and after receiving PLAC, 25 mg P, or 30 mg M plus 25 mg P. PATIENTS: Seven COPD patients (FEV1=0.99 +/- 0.30 L, Vo2max=990 +/- 315 mL/min) who were ventilatory-limited. SETTING: Veterans Affairs medical center. RESULTS: After the patients ingested M-P, the increase in the Vo2max (129.0 +/- 104 mL/min), the workload (10.0 +/- 6.5 W) and the maximum minute ventilation (4.0 +/- 3.9 L/min) were significantly greater (p<0.05) than after PLAC ingestion (-4.8 +/- 79 mL/min, 1.4 +/- 6.9 W, and -1.6 +/- 2.4 L/min, respectively). Changes after the ingestion of M, P, o r M-PC were intermediate. The M-PC combination adversely affected the patient's reported mental status (Bond visual analog scale) more than the M-P or M regimens. No regimen significantly affected the reaction time. CONCLUSIONS: We conclude that the administration of 30 mg of M plus 25 mg of P significantly improves the exercise tolerance of patients with COPD, without significantly impairing the mental capabilities of the subjects. The utility of this regimen over longer time periods needs to be evaluated.

Administration, Oral↗
PubMed1996

Comparison of oxygen saturation by pulse oximetry and co-oximetry during exercise testing in patients with COPD.

INTRODUCTION: Measurement of oxygen saturation by pulse oximetry (SpO2) is frequently performed during exercise testing of patients with COPD to monitor for hypoxemia. The purpose of this study was to assess the accuracy and precision of pulse oximetry during exercise. We hypothesized that the SpO2 would more closely reflect oxygen saturation as measured by co-oximetry (SaO2) when it was corrected for carboxyhemoglobin (COHb). We also hypothesized that SpO2 would more closely reflect SaO2 when the pulse rate by oximeter was equivalent to the heart rate by ECG. Finally, we hypothesized that SpO2 would be a better measure of SaO2 at maximal workloads than at rest or submaximal workloads. METHODS: Eight white men with severe COPD (mean +/- SD FEV1, 0.91 +/- 0.37) underwent progressive, symptom-limited exercise testing by cycle ergometry. SaO2 was measured from arterial blood at each workload using a co-oximeter. SpO2 and pulse rate were obtained by a pulse oximeter (Ohmeda 3700). Heart rate was continuously monitored by ECG. RESULTS: Reliable oximetric values as determined by a dicrotic notch in each waveform and adequate signal intensity were obtained in all eight patients. SpO2 was a moderately accurate measure of SaO2 (bias, 1.7%; precision, 2.9). The bias actually increased (4.1%) when SpO2 was corrected for COHb. Accuracy of SpO2 was not improved when pulse rate by oximetry and heart rate by ECG were equivalent, nor was the accuracy improved at maximal workloads relative to submaximal workloads during the exercise test. CONCLUSION: Oxygen saturation as measured by pulse oximetry (SpO2) in patients with COPD undergoing exercise testing is not sufficiently accurate to replace SaO2 as the gold standard for oxygen saturation.

Carboxyhemoglobin↗
PubMed1996

Sleep apnea impairs the arousal response to airway occlusion.

We hypothesized that the increased arousal threshold to upper airway occlusion exhibited by patients with obstructive sleep apnea (OSA) is in part secondary to the disease process itself. To test this hypothesis, we studied the effects of withdrawal of three nights of nasal continuous positive airway pressure (CPAP) treatment on arousal in six male patients with severe OSA who were using nasal CPAP on a long-term basis. During the control week, patients slept with nasal CPAP at home and on the first of 2 nights in the sleep laboratory (night C1, CPAP; night C2, no CPAP). During the apnea week, patients slept without nasal CPAP for 2 nights at home and 2 nights in the sleep laboratory (AP1, AP2). The control and apnea weeks were consecutive and in random order. The mean (+/-SEM) apnea+hypopnea index was 76.9 +/- 7.1 on AP1 vs 3.1 +/- 1.0 events per hour on C1 (p<0.05). Thus, the laboratory night (and presumably the 2 nights at home) preceding AP2 had dramatic increases in apnea compared with the nights preceding C2. The apnea duration during nonrapid eye movement sleep on nights following apnea was greater (AP2: 28.7 +/- 1.5 vs C2: 25.5 +/- 1. 7 s; p<0/05) and the arousal threshold as reflected by the maximum esophageal pressure deflection preceding arousal was higher (DPmax) (AP2: 55.1 +/- 5.7 vs C2: 45.3 +/- 6.4 cm H2O; p<0.005). We conclude that prior sleep apnea increases the arousal threshold to upper airway occlusion on subsequent nights and prolongs the apneic events.

Adult↗
PubMed1996

Evolution of idiopathic pleural effusion: a prospective, long-term follow-up study.

UNLABELLED: The management of idiopathic pleural effusion remains controversial. Because the long-term evolution of this entity is not well known, two different approaches, aggressive and conservative, have been proposed. We conducted a 10-year study of the evolution of idiopathic pleural effusion. METHODS: Between 1984 and 1994, we prospectively studied 40 consecutive patients (30 men and 10 women; mean [+/- SD] age, 53.8 +/- 19.4 years) with exudative pleural effusion undiagnosed after exhaustive evaluation. The pleural fluid adenosine deaminase level was below 43 IU/L in all; periodic chest radiographs and clinical evaluation were carried out in all patients for a mean of 62 months (range, 36 to 108 months). Further diagnostic procedures were performed whenever the effusion recurred or when indicated by the clinical picture. RESULTS: Effusions resolved in a mean time of 5.6 months (range, 7 days to 48 months). Five patients (12.5%) had one or more relapses of their pleural effusion, and in a further 5 (12.5%), the effusion persisted unchanged for more than 1 month. In 32 cases (80%), no potential cause of the effusion was detected. The diagnoses in the remaining eight cases were asbestos pleural effusion in three, pulmonary adenocarcinoma in one, mesothelioma in one, congestive heart failure in one, liver cirrhosis in one, and rheumatoid arthritis in one. Tuberculosis was not detected in any of the cases, although 19 patients initially had positive tuberculin tests. CONCLUSIONS: Most idiopathic pleural effusions follow a benign course. Our results support conservative treatment of patients with idiopathic pleural effusion. Antituberculous treatment does not appear to he warranted, regardless of tuberculin test results, if the pleural fluid adenosine deaminase level is not elevated.

Aged↗
PubMed1996

Arterial blood gas changes during breath-holding from functional residual capacity.

Breath-holding serves as a model for studying gas exchange during clinical situations in which cessation of ventilation occurs. We chose to examine the arterial blood gas changes that occurred during breath-holding, when breath-holding was initiated from functional residual capacity (FRC) while breathing room air. Eight normal subjects who had a radial artery catheter placed for another study were taught to breath-hold on command from FRC. FRC was determined using respiratory inductance plethysmography. Arterial blood gas specimens were obtained at 5-s intervals until the termination of breath-holding. The average breath-holding time (+/-SD) was 35 (+/-10 s). The PaO2, PaCO2, and pH values were plotted against time and individually fit to logistic equations for each subject. The arterial PaO2 fell by a mean of 50 mm Hg during the first 35 s of breath-holding under these conditions, while the arterial PCO2 rose by a mean of 10.2 mm Hg during the first 35 s and the pH fell by a mean of 0.07 in the first 35 s. The rapid decline in PaO2 is greater than that previously reported using different methods and should be considered in clinical situations in which there is an interruption of oxygenation and ventilation at FRC while breathing room air. The changes in PaCO2 and pH are similar to those previously reported in paralyzed apneic patients.

Adolescent↗
PubMed1996

Measurements of membrane diffusing capacity and pulmonary capillary blood volume in normal subjects and patients with mild emphysema.

OBJECTIVE: To establish predicted values of membrane diffusing capacity (Dm) and pulmonary capacity blood volume (Vc), to compare the predicted values from our equations with those for Caucasians, to determine whether there are changes initially in Dm or Vc in patients with mild emphysema. PATIENTS AND METHODS: Diffusing capacity for carbon monoxide (DLco), Dm and Vc were determined in 86 normal subjects and 16 patients using the single-breath diffusing capacity for carbon monoxide (DLcosB) with two different alveolar concentrations of oxygen. RESULTS: The predicted equations are as follows. For males, DLco (ml/min/mm Hg) = 0.37H-0.19A-27.8; Dm (ml/min/mm Hg) = 0.65H-0.24A-53.7; Vc(ml) = 0.88H-78.9. For females, DLco = 0.28H-22.7; Dm = 0.59H-53.6; Vc = 66.6-0.36A. DLco and Vc are lower in Chinese than Caucasians while Dm is similar in Chinese and Caucasians. Eleven of 16 patients had a low DLco (< 80% predicted value), 12 had a low Dm and 5 had a low Vc. Eight of 12 patients with a low Dm also had a low DLco, but in 4 the DLco was normal. Nine of 12 with low Dm had a normal Vc. CONCLUSIONS: This study provides prediction equations of Dm and Vc. Chinese have a low DLco because their Vc is lower than Caucasians. The DLco and Dm are abnormal in a comparable percentage of patients. In patients with mild emphysema, the Dm becomes abnormal before the Vc.

Adolescent↗
PubMed1996

Pleural disease.

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Cytokines↗
PubMed1995

Intrapleural talc for the treatment of malignant pleural effusions secondary to breast cancer.

BACKGROUND: The management of malignant pleural effusions secondary to breast cancer is a difficult problem. In the 1980s tetracycline was probably the most commonly used sclerosing agent, but parenteral tetracycline is no longer available. Therefore, it is important to evaluate alternative sclerosing agents. This prospective study was designed to determine the efficacy of insufflated talc in producing pleurodesis in patients with pleural effusions secondary to breast cancer. METHODS: Fifty-two patients admitted between May 1985 and November 1992 to the Department of Thoracic Surgery underwent thoracoscopy and had 2 gm sterile asbestos free talc insufflated throughout the pleural space at the time of the procedure. One or two chest tubes were inserted and left in place until fluid drainage was less than 100 ml per day. RESULTS: Of the 52 patients, 5 were not evaluable. Two patients died within 30 days of the procedure. In three additional patients the lung did not expand after thoracoscopy. The intrapleural insufflation of talc was effective in preventing recurrence of pleural effusion. At 30 days there was no recurrence of the pleural fluid in 45 of the 47 (95.7%) patients. One of these patients had a recurrence of the effusion 2 months after the procedure but the remaining 44 (93.6%) had no recurrence for the duration of the study. Aerosolized talc was associated with a moderate morbidity. Six (11.5%) patients had re-expansion edema, but all recovered. Empyema developed in one patient after the procedure. No episodes of respiratory distress syndrome were observed after talc pleurodesis. CONCLUSION: The insufflation of 2 gm talc into the pleural space is an effective method to control pleural effusions secondary to breast cancer.

Adult↗
PubMed1995

Triazolam in patients with obstructive sleep apnea.

The purpose of this study was to assess the effect of triazolam (0.25 mg) on apnea duration and the arousal response to airway occlusion during sleep in patients with severe obstructive sleep apnea (OSA). Twelve male subjects with a mean (+/- SD) age of 46.6 +/- 14.1 yr and body weight of 260.8 +/- 55.9 lb were studied on two nights separated by a nonstudy night. They ingested triazolam (0.25 mg) or placebo 0.5 h before bedtime in a randomized double-blind crossover manner. In non-rapid-eye-movement (NREM) sleep, the mean (+/- SEM) duration of apnea/hypopnea was slightly increased (26.8 +/- 1.7 versus 23.8 +/- 1.2 s, p < 0.02) and the mean nadir in arterial oxygen saturation lower (80.1 +/- 1.9 versus 84.2 +/- 1.4%, p < 0.001) on triazolam nights. In NREM sleep, the deflections in esophageal pressure prior to apnea termination were higher on triazolam nights (53.3 +/- 5.4 versus 44.5 +/- 4.8 cm H2O, p < 0.001). However, the rate of increase in inspiratory effort (esophageal pressure deflections) during obstructive events was not decreased by triazolam. We conclude that triazolam increases the arousal threshold to airway occlusion, but that this results in only modest prolongation of event duration and increased desaturation at a dose of 0.25 mg in a group of large sleep apnea patients.

Adult↗
PubMed1995

Temporal evolution of pleural fibrosis induced by intrapleural minocycline injection.

Minocycline is as effective as tetracycline in inducing pleural fibrosis, but the long-term pleural changes induced by minocycline are unknown. The objective of this study was to evaluate in rabbits the evolution of the pleural changes induced by the intrapleural instillation of minocycline. Under light anesthesia, minocycline at 10 mg/kg in a total volume of 2 ml of bacteriostatic saline solution was injected into the right pleural space of 25 male rabbits. The animals were sacrificed in groups of five at 15 d and 1, 2, 4, and 6 mo. Macroscopic and microscopic examinations of the pleura were performed for evidence of pleural fibrosis and inflammation. Similarly, the underlying lung was also examined for microscopic alveolar fibrosis and inflammation. During the 6-mo observation period there was no significant change in the degree of pleural fibrosis. In contrast, microscopic pleural inflammation, alveolar fibrosis, and alveolar inflammation all decreased significantly over the observation period. In conclusion, intrapleural minocycline injection results in persistent pleural fibrosis at 6 mo. It remains to be determined whether the pleural fibrosis will persist beyond this period.

Animals↗
PubMed1995

Effect of upper airway anesthesia on obstructive sleep apnea.

We hypothesized that upper airway mechanoreceptors contribute to the arousal stimulus that occurs with upper airway occlusion in obstructive sleep apnea (OSA). If so, upper airway anesthesia (UAA) should reduce the arousal stimulus and impair the arousal response. To test this hypothesis, we studied the effects of UAA on apnea duration and the esophageal pressure deflection before arousal in a group of patients with severe OSA. On two study nights separated by one week, subjects were monitored for 2 h after lights out. They were then awakened and either 5 cc of 4% lidocaine or saline (random order) was dripped into the upper airway via the nose over 10 min. Another 2 h of monitoring was then performed. Variables on the first and second parts of the control (C1 and C2) and lidocaine nights (L1 and L2) were compared during non-rapid eye movement sleep using the analysis of variance. With lidocaine, the mean (+/- SEM) apnea duration increased from 24.2 +/- 2.6 (L1) to 30.7 +/- 2.3 (L2) s but with saline the apnea length was unchanged from 23.3 +/- 1.5 (C1) to 23.4 +/- 1.6 (C2) (L2 > [L1, C1, C2], p < 0.01). In addition, the maximum esophageal pressure deflection (cm H2O) before arousal increased after lidocaine from 63.6 +/- 14.5 (L1) to 84.1 +/- 14.7 (L2) but after saline was unchanged from 62.1 +/- 15.4 (C1) to 60.0 +/- 15.2 (C2), (L2 > [L1, C1, C2], p < 0.05). We conclude that UAA impairs the arousal response to airway occlusion. This suggests that input from upper airway mechanoreceptors during obstructive events contributes to the total arousal stimulus in patients with OSA.

Anesthesia, Local↗
PubMed1995

Corynebacterium parvum versus tetracycline as pleural sclerosing agents in rabbits.

Tetracycline has been one of the most commonly used agents for producing a pleurodesis. However, it is no longer available due to more stringent requirements on the manufacturing process. The objective of this project was to determine whether Corynebacterium parvum is an effective sclerosant in an experimental model in rabbits. The following medications were instilled intrapleurally in anaesthetized male rabbits: tetracycline 35 mg.kg-1 or C. parvum 4 or 8 mg, all diluted with bacteriostatic saline solution. Twenty eight days after the instillation, the animals were sacrificed and the pleural spaces assessed macroscopically for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of C. parvum was ineffective in creating pleural fibrosis. The mean degree of pleurodesis in the 10 rabbits who received tetracycline was 3.5 +/- 0.7 (scale 0-4) whilst in the 10 rabbits that received 4 mg C. parvum it was 0.0 +/- 0.0, and in the 10 rabbits that received 8 mg C. parvum it was 0.5 +/- 0.8. Based on this study, we recommend that C. parvum should not be used as a pleural sclerosant in patients with normal pleura.

Animals↗
PubMed1995

Comparison of the end-tidal arterial PCO2 gradient during exercise in normal subjects and in patients with severe COPD.

We undertook the present study with the following objectives: (1) to compare the difference between the end-tidal and the arterial carbondioxide concentration (P[ETa] CO2) gradients at rest and during exercise in normal subjects and patients with COPD; and (2) to analyze the factors contributing to this gradient. We studied seven normal subjects and seven patients with COPD using a symptom-limited exercise test on a cycle ergometer. Our results show that the P(ET-a)CO2 increased progressively as the individuals went from rest to higher workloads in both the normal group and in the COPD group. The P(ET-a)CO2 in patients with COPD both at rest (-3.24 +/- 2.78 mm Hg) and during exercise (1.03 +/- 2.23 mm Hg) is significantly lower than that in normal individuals at rest (1.84 +/- 3.68 mm Hg) and during exercise (10.3 +/- 6.5 mm Hg) (p < 0.01). However, the slope for the relationship between the P(ET-a)CO2 and the workload is actually significantly steeper in the patients with COPD. Although the P(ET-a)CO2 correlated significantly with the workload in both normal subjects (r = 0.63, p < 0.001) and patients (r = 0.55, p < 0.005), the P(ET-a)CO2 was much more closely correlated with the ratio of dead space to tidal volume (VD/VT) (r values of -0.86 and -0.77, respectively). Moreover, when multiple regression analysis was performed, addition of any other physiologic measure (eg, oxygen consumption [VO2], carbon dioxide production [VCO2], minute ventilation [VE], or workload) as a second independent variable after the VD/VT did not improve the correlation. This indicates that the correlation between the P(ET-a)CO2 and the workload is probably related to the dependence of the VD/VT on the workload. The PaCO2 in normal subjects and in the COPD group correlated significantly with the partial pressure of end-tidal carbon dioxide (PETCO2). Using multiple regression analysis, with the PaCO2 as the dependent variable and the PETCO2 (along with other physiologic measures) as the independent variables, we found that the standard error of the estimate was still above 2.1 mm Hg in normal subjects and in patients with COPD. We conclude that (1) during exercise, the P(ET-a)CO2 in normal subjects and in patients with COPD increases significantly, (2) the P(ET-a)CO2 gradient is more closely correlated with the VD/VT than any other physiologic variable, and (3) changes in the PETCO2 during exercise are not correlated closely with changes in the PaCO2.

Adult↗
PubMed1995

Diagnosis of pleural effusions. Experience with clinical studies, 1986 to 1990.

OBJECTIVES: To identify in patients with pleural effusion which procedures are most useful in separating malignant from nonmalignant pleural effusions and to identify which procedures most commonly lead to a definitive diagnosis. DESIGN: Prospective consecutive case series. SETTING: Pulmonary referral hospital in Prague, Czech Republic. PATIENTS: One hundred seventy-one adults between ages 18 and 70 years with a pleural effusion and a Karnofsky score of 70 or above. INTERVENTIONS: All patients underwent history, physical, pleural fluid cytologic study, laboratory evaluation of serum and pleural fluid, pleural biopsy, bronchoscopy, and lung scan and/or pulmonary arteriogram. RESULTS: In this series in which 45% of the patients had malignant effusions, 19% had paramalignant effusions, and 36% had benign diseases, the pleural fluid cytologic study was the best for establishing a diagnosis. The pleural fluid carcinoembryonic antigen (CEA) levels above 10 had a high specificity (90%) for malignancy but had low sensitivity (37%). The pleural fluid CEA level was increased only in 19% of patients with paramalignant effusions. Although there were statistically significant differences in the mean results on several biochemical tests of pleural fluid, none were very accurate in separating malignant from benign disease. CONCLUSION: From this study, we conclude that patients with an undiagnosed pleural effusion should be evaluated in an individualized stepwise manner. If malignancy is strongly considered, the initial three steps should be relatively noninvasive and include clinical evaluation and cytologic study.

Adolescent↗
PubMed1995

Talc slurry is an effective pleural sclerosant in rabbits.

Insufflated talc is probably the most effective agent for creating a pleurodesis both in the clinical situation and in animals. However, the insufflation of talc requires an invasive procedure such as thoracoscopy or thoracotomy. Recently, there have been reports that talc in a slurry was effective in the clinical situation. The objective of this project was to determine whether talc in a slurry at varying doses is an effective sclerosant in an experimental model in rabbits. Talc, 50, 100, 200, and 400 mg/kg, in a 2-mL slurry was injected intrapleurally through a small catheter in male rabbits. Eleven rabbits received each dose. Twenty-eight days after the instillation, the animals were killed. The pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The degree of pleurodesis (on a scale of 0 to 4) after the injection of 50, 100, 200, and 400 mg/kg of talc was 1.1 +/- 0.9, 1.5 +/- 1.1, 2.7 +/- 0.6, and 3.4 +/- 0.5, respectively. The degree of microscopic fibrosis similarly increased with increasing doses of talc. These scores were similar to those we have reported with the tetracycline derivatives. In contrast to the results with tetracycline derivatives, none of the rabbits developed fibrothorax or hemothorax. From this study, we conclude that talc in a slurry is a very effective pleural sclerosant in rabbits and does not produce hemothoraces as do the tetracycline derivatives.

Animals↗
PubMed1995

Comparison of silver nitrate and tetracycline as pleural sclerosing agents in rabbits.

The ideal agent to produce pleurodesis has not been identified. Tetracycline, the drug used most commonly in the 1980s, is no longer available. Talc either aerosolized or in a slurry is the agent used just most commonly at the present time, but there are concerns about its safety. Another possibility is silver nitrate, which was widely used in the past, but was abandoned on account of side effects. We hypothesized that lower concentrations of silver nitrate than had been used in the past would be effective in creating a pleurodesis in rabbits. The following medications in a total volume of 2 mL were instilled intrapleurally in three groups of ten anesthetized rabbits: 0.25% or 0.50% silver nitrate and 35 mg/kg tetracycline. Twenty-eight days after the injection, the animals were sacrificed and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of 0.50% silver nitrate produced an effective pleurodesis. The mean degree of gross pleurodesis in the rabbits that received 0.50% silver nitrate (3.4 +/- 1.2) did not differ significantly from that of the rabbits that received tetracycline (3.5 +/- 0.7) (scale 0 to 4). The mean degree of microscopic pleural fibrosis in the rabbits that received 0.50% silver nitrate (3.4 +/- 0.7) did not differ significantly from that of the rabbits that received tetracycline (3.9 +/- 0.3). However, 0.25% silver nitrate was ineffective in creating pleural fibrosis, either grossly or microscopically. No rabbits died after the intrapleural injection of the drugs. There were no observed side effects after the injection of silver nitrate. The present study demonstrates that 0.50% silver nitrate instilled into the pleural space is an effective agent for producing pleurodesis in the rabbit; its effect is comparable to tetracycline 35 mg/kg. This agent should be compared with tetracycline derivatives and talc in studies in humans.

Analysis of Variance↗