Body positional effect on gas exchange in unilateral pleural effusion

The positional effect on gas exchange was studied in eight patients who had unilateral pleural fluid without clinical or radiologic evidence of parenchymal lung disease. In all eight patients, PaO2 values were higher when the lung with the pleural fluid was uppermost. The mean PaO2 in this position was 71.9 +/- 9.3 mm Hg (mean +/- SE) compared with 66.7 +/- 8.7 mm Hg in the lateral decubitus position with the pleural fluid lowermost. The mean difference in PaO2 between the two positions was 5.1 +/- mm Hg (p less than 0.005). Larger positional differences were found in the patients with the smallest pleural effusions. These results are probably due to perfusion of areas of unventilated lung, accentuated by gravity with a consequent increase in shunting. A large effusion also causes a decrease in perfusion, so that ventilation-perfusion mismatching is decreased and the positional effect on gas exchange diminished.     

体位改变对单侧胸腔积液患者气体交换的影响

目的　观察单侧胸腔积液患者患侧和健侧卧位对动脉血氧分压的影响以及体位对气体交换的影响与肺功能之间的关系。方法 采用自身对照设计、显著性检验和直线相关分析等方法。结果 53例单侧胸腔积液患者患侧卧位时PaO₂(PaO₂-E)为67.8±15.3mmHg,健侧卧位时(PaO₂-N)为79.9±13.8mmHg,二者差值在2.3～26.4mmHg之间,平均12.1±6.9mmHg,差异有显著性意义(P<0.001)。其中40例PaO₂-N高于PaO₂-E,13例PaO₂-N低于PaO₂-E。X线胸片上积液量的多少及肺功能指标与ΔPaO₂N-E之间无明显的相关。结论 体位变化对单侧胸腔积液患者的气体交换确实存在一定的影响。尽管大多数患者健侧卧位时血气交换状况改善,但并不呈一致性变化,健侧和患侧卧位血气的变化与患者的肺功能指标F-EV1及FVC也没有显著的相关。     

The effect of positional changes on oxygenation in patients with pleural effusions

In unilateral parenchymal pulmonary disease, arterial oxygenation decreases when the patient is positioned such that the abnormal lung is dependent; however, few studies have evaluated the effect of the body position on oxygenation in patients with unilateral or asymmetric pleural effusions. To our knowledge, no previous study has evaluated the possible transient effects of changing position on the level of arterial oxygen saturation (SaO2) in such patients. Accordingly, we studied ten normoxic patients spontaneously breathing room air, who had asymmetric pleural effusions as documented by chest x-ray film and physical examination. We monitored pulse, respiratory rate, and blood pressure every five minutes and SaO2 by ear oximetry continuously while patients were in the following positions: sitting; supine; and left and right lateral decubitus. The mean SaO2 was 95 percent and 94.3 percent in the sitting and supine positions, respectively. Mean SaO2 fell to 93.4 percent when the patients were positioned so that the side with the largest pleural effusion was dependent. When the side with the pleural effusion was down, the mean SaO2 was significantly lower than in either the sitting position or with the side with the pleural effusion up. We could find no significant relationship between the size of the pleural effusion and the amount of arterial oxygen desaturation. We conclude that there is a decrease in SaO2 in normoxic patients when the side with the larger pleural effusion is dependent; however, this decreased SaO2 does not appear to be clinically significant in patients with normal SaO2.     

Effects of unilateral pleural symphysis on respiratory system mechanics and gas exchange in anesthetized dogs

Lateral thoracotomy with pleural abrasion and application of talc was performed on 8 adult beagle dogs. The dogs had no effusion detectable on roentgenogram at the time of study, and obliteration of the pleural space was later confirmed by autopsy. With the dogs under pentobarbital anesthesia, lung mechanics and gas exchange were studied before and 5 wk after surgery. Total lung capacity decreased to 78% of control value (p less than 0.05). After the operation, pressure-volume curves of the respiratory system were shifted down, along with significantly decreased compliance. Maximal flow at constant lung volume was not significantly increased. Arterial O2 and CO2 tensions were not significantly different. Rebreathing DLCO normalized for lung volume was unchanged. The slope of phase III of a single-breath nitrogen test was increased (p less than 0.05) after surgery. Unilateral surgical obliteration of the pleural space results in a pure restrictive pattern. It does not affect the gas exchange surface. The increase in the slope of phase III is suggestive of a nonhomogeneous distribution of ventilation.     

Effectiveness of tunneled pleural catheter placement in patients with malignant pleural effusions

Pleural effusions (PE) occur frequently among patients with various types of advanced malignancies, resulting in remarkably decreased quality of life. Treatment of malignant PE includes placement of a chest tube with subsequent placement of a tunneled pleural catheter. We reviewed our experience with tunneled pleural catheter use to assess outcomes and resource utilization of this intervention. A retrospective study of consecutive patients (n = 163, including 41 outpatients) who were treated between July 2001 and April 2008 with tunneled pleural catheters was performed to evaluate operative and discharge outcomes. The average age of the patients was 59.32 years (range: 24 to 89). Lung cancer, breast cancer, and ovarian cancer were common primary diseases in this patient population. The mean hospital stay after tunneled pleural catheter placement was 3.19 days (range: 0 to 56), with 41 patients treated as outpatients. Thirteen inpatient deaths were related to the patients'' primary diseases, but no deaths were due to drain placement itself. Eight patients (4.91%) required reoperation to replace a nonfunctioning drain or to add an additional drain, and six patients underwent a second procedure to place a contralateral drain. One hundred twenty-six patients (77.30%) were discharged home following the procedure and hospital stay. Fifty-five people achieved spontaneous pleurodesis. Tunneled pleural catheter placement is a safe and effective approach to the treatment of PE. The advantages of tunneled pleural catheter placement include symptomatic relief and improved quality of life. This method allows patients to spend time at home with their family and avoid prolonged hospitalization.     

Useful tests on the pleural fluid in the management of patients with pleural effusions.

Examination of the pleural fluid is useful in establishing the etiology of a pleural effusion. Transudative pleural effusions can be differentiated from exudative pleural effusions by measuring the levels of protein and lactic acid dehydrogenase in the pleural fluid and serum. If a patient clinically appears to have a transudative pleural effusion, but the pleural fluid meets exudative criteria, demonstration that the albumin levels is more than 1.2 gm/dl higher in the serum than in the pleural fluid provides evidence that the effusion is transudative. The gross appearance of the pleural fluid should always be noted. Other tests that routinely should be obtained on exudative pleural fluids are Gram stain and cultures, cell counts and differential, glucose, amylase, lactic acid dehydrogenase, cytology, and a marker for tuberculous pleuritis. The diagnosis of tuberculous pleuritis is strongly suggested by a pleural fluid adenosine deaminase level above 45 IU/L or a gamma interferon level above 3.7 U/ml.     

The evaluation of pleural effusions in patients with heart failure

PURPOSE: To determine the causes of pleural effusions in patients with heart failure, and the association of the characteristics of these statistics with the use of diuretics. SUBJECTS AND METHODS: Eighty-one patients with a definite diagnosis of heart failure who underwent thoracentesis were evaluated. Fluids were classified as transudates or exudates using Light's criteria. RESULTS: Forty-one effusions (in 34 patients) were transudates, and 54 (in 47 patients) were exudates. A specific cause was found for 32 of the exudates (27 patients); except for heart failure, no obvious cause was found for the remaining 22 fluids (20 patients). Exudates with a specific cause for an exudate were more likely to have at least two of Light's criteria (18 of 27 [67%]) than did exudates without a known cause (2 of 21 [10%]). Intravenous diuretic therapy in the 24 hours before thoracentesis was significantly more common among patients with exudates without a specific cause. CONCLUSIONS: Patients with heart failure may have exudative pleural effusions without an obvious cause except heart failure.     

Lymphocyte subpopulations analysis in pleural fluid and peripheral blood in patients with lymphocytic pleural effusions.

Lymphocyte subpopulations analysis by an 11-monoclonal antibody (MoAb) panel was carried out in pleural fluid and in peripheral blood in 30 patients affected by newly diagnosed, untreated pleural effusion of different etiology determinated with bacteriological, cytological or histological criteria. Lymphocytes were the predominant cell type, in pleural fluid, in neoplastic pleural effusions as well as in congestive heart failure pleural effusions and, especially, in tuberculous pleural effusions. Lymphocyte analysis in pleural fluid and in peripheral blood suggests the involvement of different mechanisms for the lymphocyte accumulation in the pleural space according to different etiologies. Tuberculous pleural effusions showed an evident CD4+ and TEC T5.9+ lymphocyte accumulation from peripheral blood. In these patients, cutaneous skin test response to purified protein derivative was strongly related to this situation. In neoplastic pleural effusions there was a lower percentage of CD4+ lymphocytes, reflecting circulating lymphocyte pool; however, in neoplastic pleural effusions, various lymphocyte patterns may be sometimes observed depending on different histologies. Passive lymphocyte accumulation seems to be the most important mechanism in congestive-heart-failure pleural effusions.     

Update on uncommon pleural effusions

Although infections, malignancies and heart failure are responsible for the majority of pleural effusions, there are many other causes and several uncommon but distinctive types of pleural fluid. For this update we have chosen several uncommon forms of pleural effusions or disorders in which there have been recent advances in our understanding over the past several years. Chylothorax, pseudochylothorax and urinothorax are associated with characteristic clinical contexts and pleural fluid parameters but are likely underdiagnosed. Yellow nail syndrome is a rare disorder that can be associated with chylothorax and manifests multisystem features. Recognition of these entities is important because each of these disorders is associated with distinctive aetiology and management modalities. Correct diagnosis depends on the clinician's awareness of the clinical contexts and manifestations along with diagnostic pleural fluid findings in these disorders.     

Mesothelial cells in tuberculous pleural effusions of HIV-infected patients

The scarcity of mesothelial cells is a well-known characteristic of tuberculous pleural effusions. We report three HIV-infected patients with tuberculous pleural effusions, in which mesothelial cells were found in significant numbers in the pleural fluid. Clinicians should be aware that the altered immune responses that occur in HIV-infected patients may affect the cytologic profile of tuberculous pleural effusions, and they should be cautious not to exclude this diagnosis based solely on the presence of mesothelial cells in the fluid.     

Plasma B-type natriuretic peptide in patients with pleural effusions: preliminary observations

STUDY OBJECTIVES: To address the value of plasma B-type natriuretic peptide (BNP) concentrations as a diagnostic tool for determining the cardiac etiology of pleural effusions, and to determine possible differences of plasma BNP concentrations before and after pleurocentesis in patients with congestive heart failure (CHF). DESIGN: Observational study. SETTING: Tertiary care hospital. PATIENTS: Consecutive series of 64 patients with indications for diagnostic pleurocentesis. The final diagnosis of the underlying disease was assessed by clinical criteria. Seven patients were excluded due to pleural effusions of equivocal origin or due to obvious hemothorax secondary to trauma. INTERVENTION: Pleurocentesis attempting to drain effusions dry. Plasma BNP concentrations were measured directly before pleurocentesis and 24 h after the intervention. During these 24 h, the dosages of patients' medications were held constant. MEASUREMENTS AND RESULTS: In distinguishing between patients with pleural effusions caused by CHF (n = 31) and patients with pleural effusions attributable to other causes (n = 26), the area under the curve was 0.974 (SE, 0.021; 95% confidence interval, 0.892 to 0.997) for plasma BNP. A BNP cutoff concentration of 2,201 ng/L had a sensitivity of 77% and a specificity of 100% in the diagnosis of CHF. The median plasma BNP concentrations in patients with pleural effusions caused by CHF (n = 31) did not change within 24 h after pleurocentesis compared with the concentrations obtained before the procedure (before pleurocentesis, 3,227 ng/L; 24 h after pleurocentesis, 2,759 ng/L; p = 0.189), despite a median removal of 1,100 mL pleural fluid. CONCLUSIONS: Plasma BNP concentrations of patients with pleural effusions of unknown origin may be an aid in the diagnosis of CHF as the underlying cause. If plasma BNP is used as a surrogate marker of global cardiac function, there is no indication of hemodynamic improvement caused by pleurocentesis alone in patients with CHF and pleural effusions.