Lymph flow in sheep with rapid cardiac ventricular pacing

A study of patients with isolated mediastinal and hilar lymphadenopathy undergoing EBUS-TBNA

Background

Isolated mediastinal and/or hilar lymphadenopathy (IMHL) may be caused by benign and malignant disorders or be ‘reactive’. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has a reported low negative predictive value (NPV) in IMHL, necessitating mediastinoscopy in selected patients. The aim of this study was to examine the NPV of EBUS-TBNA in an IMHL population and determine whether clinical variables differentiate between pathological and reactive IMHL.

Methods

Analysis of a prospectively maintained database of consecutive patients with IMHL referred to a single UK centre for EBUS-TBNA.

Results

100 patients with IMHL had EBUS-TBNA during the study (March 2010–February 2013), mean age 58.6±15.7 years, 63% men, 70% white British and mean follow-up 16.8±8.6 months. Pathological cause of IMHL established in 52 patients (sarcoidosis n=20, tuberculosis n=18, carcinoma n=7, lymphoma n=6, benign cyst n=1), 43 from EBUS-TBNA. 48/57 negative EBUS-TBNA samples were true negatives reflecting reactive lymphadenopathy in 48%. The diagnostic accuracy of EBUS-TBNA was 91% and NPV was 84.2% (95% CI 72.6% to 91.5%). Multivariate analysis of clinical covariates showed age (odds ratio (OR) 1.07, 95% CI 1.01 to 1.13; p=0.033), the presence of a relevant comorbidity (OR 9.49, 95% CI 2.20 to 41.04; p=0.003) and maximum lymph node size (OR 0.70, 95% CI 0.59 to 0.83; p=0.00004) to differentiate between reactive and pathological IMHL. Stratification of the study population according to comorbidity and maximum lymph node size (<20 mm) identified a low-risk cohort (n=32) where the NPV of EBUS-TBNA was 93.8% (95% CI 79.9% to 98.3%).

Conclusions

Reactive lymphadenopathy accounts for a significant proportion of patients with IMHL. In carefully selected patients with IMHL and a negative EBUS-TBNA, surveillance rather than further invasive sampling may be an appropriate strategy.

Pulmonary Air Embolization Inhibits Lung Lymph Flow by Increasing Lymphatic Outflow Pressure

BACKGROUND

Air embolization of the pulmonary vascular tree increases pulmonary microvascular filtration and induces pulmonary edema formation. Flow from cannulated pulmonary lymphatic vessels increases significantly following air embolization. However, in the intact animal, lymph flows into the venous system and the magnitude of lymph flow is directly affected by systemic venous pressure. We hypothesized that pulmonary air embolization would lead to systemic venous hypertension and that this increase in lymphatic outflow pressure would prevent an increase in pulmonary lymph flow.

METHODS AND RESULTS

Pulmonary air embolization was induced in dogs under general anesthesia. Flow from cannulated pulmonary lymphatic vessels was recorded for lymphatic outflow pressure set equal to atmospheric pressure (Q(LA)) and for outflow pressure set equal to systemic venous pressure (Q(LV)) both before and after embolization. Air embolization resulted in significant increases in systemic venous pressure from 6.4 +/- 0.3 to 12.4 +/- 1.2 mm Hg and in QLA from 48 +/- 9 to 175 +/- 29 microL . min(1). However, embolization did not increase Q(LV) (10 +/- 2 vs. 3 +/- 3 microl . min(1)).

CONCLUSIONS

Pulmonary air embolization impedes pulmonary lymph flow by increasing systemic venous pressure and, thereby, contributes to pulmonary edema formation.

Mediastinal lymphadenopathy in congestive heart failure: a sequential CT evaluation with clinical and echocardiographic correlations

The aim of this study was to evaluate the frequency and evolution after treatment of mediastinal lymphadenopathy associated with congestive left heart failure on CT scans in correlation with clinical and echocardiographic findings. Thirty-one consecutive patients with subacute left heart failure underwent a clinical evaluation using the NYHA classification, a CT examination, and transthoracic echocardiography at the time of initial presentation (T1). After initiation of medical treatment (T2), follow-up CT scans were systematically obtained together with a clinical evaluation. At T1, all patients showed severe (type III: n=12, 39%; type IV: n=12, 39%) to moderate (type I, n=1, 3%; type II, n=6, 19%) dyspnea with a mean ejection fraction of 39% (range 22-74%). On initial CT scans, enlarged mediastinal lymph nodes were seen in 13 patients (42%) with blurred contours in 5 patients (16%) and hazy mediastinal fat in 1 patient (3%). Significant decrease in the size of lymphadenopathy was observed between T1 and T2 (T1, n=13, 42% vs T2, n=10, 32%; p<0.05) with a concurrent decrease in the severity of dyspnea (grade III-IV dyspnea at T1, n=24, 78% vs grade I-II dyspnea at T2, n=26, 83.5%). Patients with enlarged lymph nodes at T1 showed: (a) a significantly lower ejection fraction at echocardiography than those without lymphadenopathy (mean+/-SD value: 34+/-12.9 vs 43+/-13.8%; p=0.04); (b) a significantly larger diameter of the right superior pulmonary vein (mean+/-SD value: 17+/-2.75 vs 14+/-3.9 mm; p=0.04); and (c) a higher frequency of abnormal peribronchovascular thickening ( n=5 vs n=1; p=0.06). Mediastinal lymphadenopathy associated with subacute left heart failure was observed in 13 patients (42%), showing regression after initiation of treatment in 8 of 13 patients (62%).