# Thoracentesis (Pleural Tap)

## Overview

This module describes how to perform thoracentesis, or a pleural tap, to drain fluid from a patient’s pleural space.

## Indications

1. Diagnostic tap for pleural effusion of unknown aetiology

2. Therapeutic tap for large, symptomatic pleural effusions that are not amenable to medical treatment

## Contraindications

1. Damaged skin or infection at the puncture site

2. Consider the risks and benefits in patients with coagulopathy

## Patient information & consent

Always verify your patient’s identity and obtain informed consent before proceeding.

### How do I explain this procedure?

“There is fluid in the space around your lung, which is pressing on the lung tissue and causing your shortness of breath. I need to draw off some of it.”

### What can my patient expect?

“I will give you an injection for pain, then I will put a needle into the collection of fluid and allow it to drain by itself. It might take a while, and you will have to sit up, leaning forward, while it drains.”

### What is my patient’s role?

“Let me know if you have any allergies or a bleeding tendency, or use blood thinners. Fearing blood or needles is normal, but tell me if you have fainted from it. Try to keep still while I do this procedure, and let me know if you feel any strange sensations or severe pain.”

## Preparation

###

### Documentation

1. Patient notes

2. Patient labels and laboratory request forms only if conducting a diagnostic tap

### Equipment

1. Sterile gloves

2. A sterile pack

3. Skin disinfectant
   Skin disinfectant

   Commonly used preparations include 0.5-2% chlorhexidine in 70% alcohol (Steriprep), or 10% povidone iodine. There is no consensus on the superiority of one agent above another. Caution: chlorhexidine solutions may be associated with burns and skin breakdown in infants < 2 months old.)

4. Lignocaine (usually 1-2% with adrenaline)

5. 18-20 G IV cannula and administration set (only for therapeutic thoracentesis)

6. Two 10 ml syringes

7. An aspiration needle (ideally blunt fill) and an injection needle

8. Alcohol swabs

9. Transparent film dressing

10. Bucket to catch fluid

11. Adhesive tape

If conducting a diagnostic tap:

####

1. 18-20 G needle

2. Sterile specimen jars and EDTA specimen tubes
   Sterile specimen jars and EDTA specimen tubes

   Specimens are usually sent for microscopy and culture, gene Xpert for TB, and chemistry analysis to assess Light's Criteria. Familiarise yourself with the containers your specific lab requires for these assessments.

3. Laboratory specimen bag

## Site & Positioning

If possible, take a chest X-ray prior to this procedure.

Ask the patient to sit, bent over forward. Tuck a linen saver or paper towel into their pants, skirt or underwear.

Percuss to find the area of dullness on their back, and find a puncture site. Avoid the cardiac region, and do not puncture below the 9th rib or above the axillary crease. Often, the best site is the 8th intercostal space posterolaterally.

## Procedure

Follow medical asepsis with sterile gloves.

1. Perform hand hygiene.

2. Draw up 5-10 ml lignocaine and anaesthetise the puncture site superficially, then along a tract down to the pleura. Stay on the upper border of the underlying rib.

3. Open the sterile pack and create a sterile field on a clean, dry surface. Pour disinfectant into the well containing cotton balls. Open the IV cannula/needle,

   administration set
   administration set

   You can shorten the administration set by cutting the lower part with a blade or scissors to speed up the drainage time, but retain the clasp which allows you to open and close the set and determine the rate of drainage.

   , syringe and dressing onto the sterile field.

4. Don sterile gloves.

5. Clean
   Clean

   Start in the middle and clean in concentric circles outwards.

   and drape the puncture site.

6. Remove the stopper and attach the syringe to the back of the IV cannula, or needle.

7. Puncture the skin and advance while aspirating with the syringe.

8. For diagnostic tap: Aspirate about 10 ml of fluid.

9. For therapeutic tap: Once fluid is aspirated,

   remove the needle
   remove the needle

   Place a finger over the back of the cannula while reaching for the IV giving set to prevent fluid from dripping or squirting out.

   of the cannula, attach the IV giving set, and allow the fluid to run through the set into the bucket. Ideally, do not leave the patient unattended while performing a therapeutic tap. If you have to do so, close the clasp on the administration set so that the fluid drains slowly. Tape the cannula to the chest wall by sticking a piece of tape underneath the cannula and crossing the ends over each other above the cannula. Do not drain more than 800 ml-1L of fluid in 24 hours as rapid third space losses cause fluid shifts which deplete the intravascular volume and can cause haemodynamic instability.

10. Remove the cannula/needle and dress with a transparent dressing.

11. For diagnostic tap: Transfer the pleural fluid to a specimen jar and send to the laboratory in a specimen bag with a laboratory request form.

12. Dispose of medical waste safely.

13. Record the completion of the procedure in patient notes.

14. Send the patient for a chest X-ray to rule out iatrogenic pneumothorax.

## Troubleshooting

I didn’t get back fluid on my first pass.

Don’t stop aspirating as you withdraw from the skin. Use a new IV cannula and try again in the adjacent space, ensuring that you have a big enough gauge cannula as specified above.

I did not get fluid back on my second pass.

Call a senior. If still unsuccessful, request a

lateral decubitus chest X-ray

lateral decubitus chest X-ray

The patient lies on their side for the X-ray (same side for effusions and opposite side for pneumothoraces). Can also distinguish between an effusion between the lungs and diaphragm, and intra-abdominal pathology. Explain on the radiography request form what you are looking for.

and check for

run off.

run off.

If the effusion is liquid and thus drain-able, it will 'run' along the pleura when the patient is placed on their side. When viewing the lateral decubitus you will see the fluid has tracked upwards along the pleura. If this does not happen and the fluid remains unchanged on the lateral decubitus view, it means the fluid is loculated or 'walled off'.

If no run off, the effusion may be loculated. This may need to be drained under ultrasound guidance.

Instead of fluid I got blood back.

If this is a tiny amount just filling the hub of the needle or cannula, continue as above. If there is a fair amount of venous blood filling the syringe, stop aspirating, withdraw the syringe and apply pressure to the site before attempting in the adjacent space.

Fluid was draining, but has stopped after only a small amount has drained.

The cannula may be kinked. Repeat the procedure using a new IV cannula. If the fluid is bloodstained, there may be a clot obstructing the cannula. Remove the administration set, check for a clot at the needle or cannula hub, and remove it. If unsuccessful, try again in an adjacent space.

## Risks

1. Pain

2. Bleeding: chest wall haematoma or haemothorax

3. Pneumothorax

4. Re-expansion pulmonary oedema

5. Sharps injury to healthcare worker

6. Vasovagal response (fainting)

## References

1. Naidoo C, Ross A. How to Do a Pleural Tap. In: Mash B, Blitz-Lindeque J, eds. South African Family Practice Manual. 2nd ed. Pretoria: Van Schaik Publishers; 2010: 102.

2. Cantey EP, Walter JM, Corbridge T, Barsuk JH. Complications of thoracentesis: incidence, risk factors, and strategies for prevention. Curr Opin Pulm Med. 2016;22(4):378-385. doi:10.1097/MCP.0000000000000285. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040091/

3. Wiederhold BD, Amr O, Modi P, et al. Thoracentesis. [Updated 2021 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441866/

4. Yu H. Management of pleural effusion, empyema, and lung abscess. Semin Intervent Radiol. 2011;28(1):75-86. doi:10.1055/s-0031-1273942. Available from: https://pubmed.ncbi.nlm.nih.gov/22379278/