The purpose of the trial is to evaluate the effectiveness of moderate to large volume thoracentesis (TC) in non-ventilated patients in Internal Medicine admitted due to, or suffer from respiratory instability. This is a prospective, double-center, randomized clinical trial. This is a stage 1 pilot trial aimed to provide better understanding on the study population and study groups. This trial will comprise a total of 60 patients, 30 subjects on the intervention group and an equal number on the control group. The results of this pilot trial will be to design a larger trial and calculate a required sample size.

The prevalence of pleural effusion is high among medical patients, reaching 62% among Medical ICU patients. Often clinicians are standing in front of a symptomatic respiratory patient with moderate or large pleural effusion. The clinical question whether TC will be beneficial for the patient with respiratory compromise is yet to be shown. There are few, small scale studies on the benefit of pleural effusion thoracentesis. Only one study found sustained effect of thoracentesis on oxygenation among 10 patients on mechanical ventilation. Lung function was found to improve after TC among patients with paradoxical movement of hemidiaphragm, and relief of dyspnea after large pleural effusion TC was demonstrated as well. No study to date, as the investigators know, on the benefit of TC, was done on non-ventilated, ward patients with moderate to large pleural effusion. Also, no studies to date showed any improved clinical outcome of this procedure.

Although ultrasound guided TC is a safer mode than blinded TC, complications as pneumothorax, pain, shortness of breath, cough, bleeding, hematoma, and re-expansion pulmonary edema may result from TC. Although no consensus exist regarding the benefit of TC still this procedure is common among ventilated and non-ventilated patients. The investigators seek to find whether there is clinical benefit for TC, among non-ventilated, ward patients with moderate to large pleural effusion. For this purpose the investigators aim to conduct a prospective randomized trial.

In this study the investigators aim to compare outcomes as: hospital length of stay, vital signs and wellbeing, utilization of imaging modalities and readmission rates among patients who had therapeutic TC compared to those who had not. Also the investigators would like to try and predict the amount of pleural effusion from the ultrasound imaging as well as to find the added value of point of care US screening of pleural effusion on top of routine Xr among patients with respiratory instability.

To the best of the investigators' knowledge, no prospective randomized study to date has compared the strategy of TC to none among non-ventilated ward patients with respiratory complains.

This is a prospective, double-center, randomized clinical trial. This is a stage 1 pilot trial aimed to provide better understanding on the study population and study groups. This trial will comprise a total of 60 patients, 30 subjects on the intervention group and an equal number on the control group. The results of this pilot trial will be to design a larger trial and calculate a required sample size.

Inclusion Criteria:

1. Patients admitted to internal ward

2. Patients with moderate to large pleural effusion per ultrasound as defined under Eligibility section below

3. At least of the following findings:

   • Dyspnea on admission notes
   • Tachypnea (RR >18 pm)
   • Desaturation (saturation<88%)
   • Admission diagnosis of CHF exacerbation or any uncontrolled heart failure,
   • Effort dyspnea per history,
   • Acute or subacute (last two weeks) need for oxygen supplement or Noninvasive ventilation.
   • Admission diagnosis of pulmonary edema or pulmonary congestion
   • Hypoxemia (PaO2<60mmHg)
   • Pleuritic chest pain

Exclusion Criteria:

1. Subject currently enrolled in another investigational study
2. Patients on mechanical ventilation
3. Patients with coagulopathy (known or with any prolongation of PTT, PT, fibrinogen<200, platelets <100000)
4. Patients with cognitive impairment who cannot sign informed consent
5. Patients with sepsis or fever and pneumonia and suspected empyema
6. Patients with any previous surgeries to the lungs
7. Patients whom the primary team call for therapeutic TC.
8. Patients with less than moderate amount of pleural effusion (see Eligibility criteria)
9. Palliative patients
10. Pregnant patients
11. On any current anticoagulation therapy or with any abnormal coagulation study.
12. Patients with septations or cavitation in pleural space (visible on US