Kenneth G. Torrington

Necessity of Routine Chest Roentgenography after Thoracentesis

Standard medical practice after thoracentesis is to obtain a posteroanterior chest roentgenogram to identify complications, most notably pneumothorax, stemming from the procedure. The chest roentgenogram is usually done routinely and without regard to the providers clinical suspicion of a procedure-related complication. This practice carries considerable expense, consumes medical resources, and opposes the 1988 American Thoracic Society guidelines [1]. To our knowledge, the necessity of routine chest roentgenograms after thoracentesis has never been prospectively evaluated. We did such an evaluation and report our results. Methods Procedure and Data Collection All inpatients 18 years of age or older having thoracentesis in the Internal Medicine Service at Walter Reed Army Medical Center were eligible to participate in this study. All patients gave consent. Thoracentesis was done using standard operating procedure with a needle or angiocath and syringe or with a prepackaged needle-catheter tray (Teflon catheter with 14 gauge 15 cm needle, Kendall Curity, Mansfield, Massachusetts), according to operator preference. After the procedure, each operator completed a preprinted procedure note. The variables recorded are listed in the Appendix. After thoracentesis, patients had portable anteroposterior or standard posteroanterior and lateral chest roentgenography. Chart review, completed by the investigators within 72 hours after the procedure, identified any further complications that had occurred in the interim. Patients were excluded if they were younger than 18 years of age, did not have a procedure note before chest roentgenography, did not have a chest roentgenogram within 4 hours of thoracentesis, had a concurrent pleural biopsy, had thoracentesis assisted by ultrasonography, or were using mechanical ventilation. Several thoracenteses could be done on one patient if they were done on different dates. In six cases, the roentgenogram obtained immediately after the procedure was not formally interpreted by the radiology department and could not be located for our review. These six films were interpreted only by the house officer, but subsequent roentgenograms showed no evidence of pneumothorax. All other films were available for interpretation. Data Analysis Exploratory analysis comparing the demographic and procedural characteristics of patients having a pneumothorax with those of patients not having a pneumothorax was done using the Wilcoxon ranksum test for continuous and ordinal variables and the Fisher exact test (two-tailed) for nominal data. We did not adjust for the number of univariate statistical tests done. For demographic characteristics, the sampling unit for analysis was the patients first tap (n = 110). We analyzed procedural characteristics using the patients first tap (n = 110) and all taps that had similar results (n = 174). Relative risk ratios were calculated as the incidence of pneumothorax in the group at risk divided by the incidence of pneumothorax in the group without risk factors. If the incidence of pneumothorax was 0, we added 0.5 to each cell and estimated the ratios. We calculated 95% CIs for each relative risk [2] and proportion. Data were analyzed using SPS 5.0 for Windows (SPS, Chicago, Illinois). Results We analyzed 174 thoracenteses done on 110 patients admitted to the Walter Reed Army Medical Center Department of Medicine between March 1991 and June 1993. These were approximately 95% of all thoracenteses done during the study period. The study sample consisted of 43 women and 67 men with a mean age of 62.4 13.2 years. Patients had either 1 (n = 71), 2 (n = 24), 3 (n = 10), 4 (n = 3), 6 (n = 1), or 7 (n = 1) thoracenteses. Nine pneumothoraces occurred in this series of 174 taps, for an incidence rate of 5.2% (CI, 2.4% to 9.6%). Among the 110 patients, six pneumothoraces occurred on the first tap (incidence of 5.5%; CI, 2.0% to 11.5%). Of the 39 patients having a second tap, 2 had pneumothoraces, for an incidence rate of 5.1% (CI, 0.6% to 17.3%). On the third tap, 1 of 15 patients had a pneumothorax, for an incidence rate of 6.7% (CI, 0.1% to 31.9%). One patient had pneumothoraces on both his first and second thoracenteses, which were done 6 months apart. The chest roentgenogram obtained immediately after the procedure identified eight of the nine pneumothoraces. Pneumothorax was suspected in five of the eight instances; tube thoracostomy was done in four of the five cases. The unsuspected pneumothoraces diagnosed in the other three cases were small (estimated by the radiologist to be less than 20%). One resolved spontaneously, the second was treated with a chest tube only to resolve a loculated effusion, and the third was untreated because the severely ill patient died approximately 6 hours after the procedure. An autopsy ruled out tension pneumothorax as the cause of death, and, because of the severity of the underlying illness, the pneumothorax was not believed to have contributed to the patients death. In the one case in which roentgenography done immediately after the procedure did not identify pneumothorax, a moderately sized (50%) ipsilateral pneumothorax was found on a chest roentgenogram obtained 3 days later. To prevent further enlargement, tube thoracostomy was done at the request of the attending physician. The pertinent characteristics of patients developing pneumothoraces are shown in Table 1. Correlations of patient and procedure characteristics with pneumothorax are shown in Table 2. Three procedure variables and one patient variable were strongly associated with the occurrence of pneumothorax. During the first thoracentesis (n = 110), aspiration of air occurred in 13 patients, and pneumothorax developed in 4 (relative risk ratio, 14.9; CI, 3.0 to 73.6). Patients who had more than one pass of the thoracentesis needle had an increased risk for developing pneumothorax (relative risk ratio, 5.6; CI, 1.1 to 28.9). Operator suspicion and existence of pneumothorax were also highly associated (relative risk ratio, 42.0; CI, 9.9 to 177.4). Five of the eight pneumothoraces confirmed by immediate chest roentgenography were suspected. In four of the five, the operator based suspicion on aspiration of air during the procedure. In the fifth case, air was audibly entrained through the catheter by the patient because of poor compliance with instructions. Finally, pneumothorax developed in 2 of 5 patients with a history of thoracic radiation therapy (relative risk ratio, 10.5; CI, 2.5 to 44.4). Table 1. Selected Characteristics of Patients with Pneumothoraces* Table 2. Patient and Procedure Correlations with Pneumothorax If we combined these criteria in our sample, 110 attempts would not have required roentgenograms, and 109 (99.1%; CI, 95.0% to 99.9%) would have been negative for pneumothorax. Among the 64 attempts requiring roentgenograms, pneumothorax would have been diagnosed in eight cases (12.5%; CI, 5.5% to 23.2%). Vital signs and physical examination findings were infrequently documented by the operators and therefore could not be interpreted. Two hemothoraces (1.2%) and two subcutaneous hematomas occurred in the study sample. Neither hemothorax was identified by roentgenography done immediately after the procedure; these diagnoses were made by evaluating pleural fluid cell counts. Both patients required chest tube drainage. Discussion Many articles have documented the various complications that occur after thoracentesis, but few have specifically evaluated or commented on the need for routine chest roentgenography after thoracentesis. In 1983, Collins and Sahn [3] reported their experience with complications after thoracentesis. They prospectively evaluated 74 hospitalized patients having thoracentesis and found a 12% incidence of pneumothorax. Routine chest roentgenograms obtained after thoracentesis showed four small clinically insignificant pneumothoraces not expected by the operators. None of these patients required further intervention. Collins and Sahn concluded their abstract by stating that routine post thoracentesis chest x-rays are unnecessary unless complications are suspected clinically [3]. In 1989, the American Thoracic Society [1] published guidelines for thoracentesis and pleural biopsy and recommended that a chest film should be performed after therapeutic thoracentesis in most instances. The necessity of chest roentgenography after thoracentesis was not specifically addressed in the medical literature again until Gerardi and colleagues [4] reported their retrospective chart review of all thoracenteses done during a 1-year period at a large community hospital. Among 134 procedures, they found a 7.5% incidence of pneumothorax. Three patients were asymptomatic and required no further intervention. Four of the seven patients with pneumothorax had new or increased dyspnea and required tube thoracostomy. In their conclusion, Gerardi and colleagues questioned the necessity of obtaining routine chest roentgenograms after thoracentesis in hospitalized patients who remained free of symptoms. The incidences of pneumothorax (5.2%; CI, 2.4% to 9.6%) and hemothorax (1.2%; CI, 0.1% to 4.1%) in our study are similar to those in other published studies [4-8]. However, the presence of pneumothorax was not predicted by the development of new symptoms. Only two of the nine patients developed new symptoms during or after the procedure. Therefore, symptoms alone could not predict the presence of pneumothorax or the need for intervention, although the development of new symptoms should never be ignored. Although other investigators have reported associations between pneumothorax and cancer and cough [4], needle-catheter technique [9], volume of aspirated fluid and needle size [10], clinical indication (diagnostic compared with therapeutic) [4, 9-11], and operator experience [4, 7, 11, 12], we found four factors associated with pneumothorax. However, because of the small nu

Evaluation of internists’ spirometric interpretations

AbstractBACKGROUND: Correct interpretation of screening spirometry results is essential in making accurate clinical diagnoses and directing subsequent pulmonary evaluation. The general internist is largely responsible for interpreting screening spirometric tests at community hospitals. However, reports of new guidelines for screening spirometry are infrequently published in the general internal medicine literature. This can lead to incorrect interpretations. We sought to evaluate whether spirometric interpretations by a group of practicing general internists differed from those of two board-certified pulmonologists using guidelines published by the American Thoracic Society (ATS). METHODS: As part of a Continuous Quality Improvement project, all available screening spirometric tests over a 3-month period at two area community hospitals were reviewed. Only those performed on individuals age 18 or older were included in the analysis. Comparison was made between the interpretations of staff internists and those of two pulmonologists, who were blinded to the results of all other interpretations. We analyzed 110 screening spirometric tests from 84 males and 26 females. The patients ranged in age from 18 to 77 (mean 41±13 years of age). RESULTS: There was 97% concordance between the two pulmonologists’ interpretations. In three cases, interpretations of only one pulmonologist agreed with those of the internists. The internists and both pulmonologists agreed in 73 cases. The majority of spirometric results in this subgroup were normal (n=54). Both pulmonologists disagreed with internists’ nomenclature in five cases. There was complete disagreement between the pulmonologists and the internists in the other 29 cases. Using the pulmonologists’ interpretations as the “gold standard,” the sensitivity (the internists’ ability to correctly identify abnormal spirometric results) was 58.8% (95% confidence interval [CI] 42.2%, 73.3%), the specificity was 81.8% (95% CI 70.0%, 89.8%), the positive predictive value was 66.7% (95% CI 49.0%, 80.9%), and the negative predictive value was 76.1% (95% CI 64.3%, 85.0%). The most common inaccurate interpretations made by internists were “small airways disease” when spirometric results were normal (n=8); “normal” when a restrictive pattern was present (n=6), and “normal” when an abnormal flow-volume loop suggesting possible upper airway obstruction was present (n=5). CONCLUSIONS: The spirometric interpretations of a group of general internists differed significantly from those of two board-certified pulmonologists using published guidelines in approximately one third of cases. This may be because sub-specialty guidelines are infrequently published in the general internal medicine literature. We believe that wider dissemination of these interpretative guidelines and ongoing physician education would improve general internists’ ability to identify patients who require further pulmonary evaluation.

Serum angiotensin converting enzyme does not correlate with radiographic stage at initial diagnosis of sarcoidosis

Serum levels of angiotension converting enzyme (ACE) are elevated in many patients who suffer from sarcoidosis. Few studies have correlated ACE levels at diagnosis with the radiographic stage of the disease. The present authors reviewed the charts of all patients who had the diagnosis of sarcoidosis made between 1990 and 1995, and correlated ACE level at diagnosis with radiographic stage. Only patients with biopsy-proven sarcoid were included. One hundred and sixteen cases were identified, and complete data were available for 104 individuals. Serum ACE levels were increased in approximately 63.5% of the study population. The relationships between both stage and ACE level, and stage and percentage of individuals with elevated ACE levels within that stage were not statistically significant (P > 0.05). This large, retrospective study of patients with histologic evidence of sarcoidosis demonstrated no association between serum ACE level and radiographic stage.