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Wet, Wacky Lungs: A Quick Look At Pleural Effusions

More is better, right? Wouldn’t draining more from your patient’s pleural effusion make them less symptomatic? Spare them from a repeat procedure? Get them home sooner? Classically, we are taught to take off no more than 1 liter of fluid, as this can lead to the dreaded phenomenon of re-expansion pulmonary edema (RPE). RPE is a rare complication occurring in less than 1% of thoracenteses but the mortality can reach up to 20%. The pathophysiology is not completely understood but a main hypothesis is that after lung re-expansion an acute inflammatory response occurs and subsequently damages the alveolar-capillary membrane.

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Articles of Interest

Safety of thoracentesis

Use your ultrasound to direct your tap and don't take out more than 1500 mL routinely.

How To Do It: Thoracentesis

Position - Midaxillary or posterior midscapular line, Placement - 1-2 rib spaces below superior aspect of effusion, superior to rib, US guidance.

Is it a Pneumothorax? An Unusual Post-Thoracentesis Radiograph

Trapped lung syndrome. This syndrome occurs when fluid is drained from the pleural cavity, but the lung fails to expand due to improper pleural healing after inflammation.

The Role of Diagnostic Thoracentesis in the Emergency Department

Indications for a diagnostic thoracentesis is the presence of a clinically significant pleural effusion (more than 10-mm thick on ultrasound or lateral decubitus radiography) with no known cause. [2] There are no absolute contraindications to diagnostic thoracentesis. Recently there have been studies that even those with coagulation abnormalities can be safely done under the guidance of ultrasound.

Thoracentesis

Have the patient in the sitting position with some lumbar flexion and with the arms resting on a bedside table for support. If the patient is unable to maintain the position on their own have an someone available to assist them. Alternatively, if the patient is unable to sit erect, place them in a supine position with the arm abducted above the head.

Thoracentesis- No X-ray required!

To perform the thoracentesis using ultrasound, the patient may be in a sitting or decubitus position. A low frequency probe is used to find an intercostal area with a large amount of pleural effusion. While a curvilinear probe may be used, the phased array probe may be preferable due to the smaller footprint.

Trapped Tap: Considerations When Performing ED Thoracentesis

There are no hard and fast rules for therapeutic thoracentesis in the ED setting but there are some accepted best practices.

Ultrasound for thoracentesis

Ultrasound also reduces the number of unsuccessful clinical attempts at thoracentesis (“dry tap”), because more than 50% of needle insertions are below the diaphragm.

Ultrasound-Guided Thoracentesis

Have patient sit upright. Visualize pleural effusion from posterior with linear probe. Mark the two ribs and interspace.

Resources

WikEM

Choose insertion site/positioning. Upright position in mid-scapular or posterior axillary line (usual technique). Lateral decubitus position with fluid side down in post axillary line (if cannot sit up). Supine with head elevated as much as possible in midaxillary line (chest tube location)