Back to top

Breathing - Thoracentesis (pneumothorax)



Spontaneous primary pneumothorax (if breathless or size >2cm at hilum)

Small asymptomatic secondary spontaneous pneumothorax in patients under 50 years ( <2cm at hilum)

Contraindications (absolute in bold)

Coagulopathy or thrombocytopenia (APTT >50 seconds, platelets <50, INR >1.5 or NOAC use in last 24 hours)

Loculated effusion or pleural adhesions (known or seen on bedside ultrasound)

Prior pleural space surgical intervention

Bullous disease

Positive pressure ventilation

Overlying skin infection

Uncooperative patient


Conservative management (no aspiration)

Small intercostal catheter (Seldinger technique)

Informed consent

Medical emergency

Consent is not required if the patient lacks capacity or is unable to consent

Brief verbal discussion is recommended if the situation allows


Written consent

More complex non-emergency procedure with higher risk of complications

Potential complications





Neurovascular, visceral and pulmonary parenchymal damage


Re-expansion pulmonary oedema


Procedural hygiene

Standard precautions

Surgical aseptic non-touch technique

PPE: sterile gloves and gown, surgical mask, eye protection, sterile ultrasound probe cover


Monitored bed space


Procedural clinician and assistant


Ultrasound machine to confirm pneumothorax

Syringe and 25g needle (local anaesthetic)

16-18g cannula or thoracentesis catheter if available

60ml syringe

Three-way tap and extension tubing

Sterile occlusive dressing

Positioning (triangle of safety preferred)

On the bed with head elevated to 45 degrees

Arm on the side of the lesion behind the patient’s head (abducted and externally rotated)

Locate safe triangle: lateral to pectoralis major, medial to latissimus dorsi, fourth or fifth intercostal space, anterior to mid-axillary line

With the arm by the side, mark the anterior mid-arm point from shoulder tip to antecubital fossa (preferred), or

Place your open hand in the axilla and mark the edge of the hand between the anterior and mid-axillary line, or

Palpate the second intercostal space at the sternal angle, move down two spaces and palpate space around to the axilla

Ultrasound-guided site of entry: two intercostal spaces below the highest level of effusion

Mark site using ultrasound confirming 10mm of fluid thickness at chosen site noting soft tissue depth


10ml lignocaine 1% with adrenaline (1:100,000)

Supplemental oxygen throughout procedure

Sequence (pleural aspiration - pneumothorax)

Mark site and measure soft tissue depth using ultrasound

Anaesthetise skin and proceed the over top of rib to anaesthetises soft tissue, muscle, periosteum

After aspirating pleural air stop advancing needle and inject final anaesthetic, then withdraw needle

Advance 16-18g cannula with syringe attached over the top of rib aspirating as you advance

After aspirating pleural air, angle the cannula caudally and insert over the needle (Seldinger technique)

Remove needle with syringe attached, leaving only plastic cannula in place and attach closed three-way tap to cannula

Attach 60ml syringe to distal three-way tap port (tap is now connected to chest, air and syringe)

Close three-way tap to air bay and withdraw 50ml into syringe

Close tap to patient and push syringe air through three-way tap into the procedure bay (air)

Repeat process, keeping track of the total amount of air aspirated

Repeat, up to a maximum of 3l air aspirated

After procedure, remove catheter as patient holds breath at end expiration

Cover insertion site with occlusive dressing

Post-procedure care

Analgesia if required

Monitor for respiratory distress or haemodynamic compromise for four hours

Post-aspiration chest X-ray, and repeat at four hours

Discussion with respiratory physician after X-ray (consider repeat aspiration or drain if ineffective)

Document procedure (completion, method, complications)


Observation is the treatment of choice for small primary spontaneous pneumothorax without breathlessness

The risk of bleeding with a small needle is low even if the patient has an uncorrected coagulopathy


In defining pneumothorax management strategy, the size of a pneumothorax is less important than the degree of clinical compromise. Breathlessness indicates the need for aspiration or a drain as well high flow oxygen. A larger pneumothorax will take longer to spontaneously resolve (2% thoracic volume per day) and is a relative indication for aspiration or a drain.

We recommend the primary attempt for needle thoracentesis is a 5cm cannula placed perpendicular to the skin in the fourth or fifth intercostal space between the anterior to mid-axillary line as suggested by the British Thoracic Society guidelines. Other positions such as the midscapular line (while sitting forward) or posterior axillary line (while lying on side with effusion down) are also acceptable, provided this is above the ninth rib (two rib spaces below the tip of the scapular) to avoid abdominal visceral injury. Aspirations at the second intercostal space midclavicular line have a high failure rate with a 5cm catheter and are generally not recommended.

Re-expansion pulmonary oedema rarely occurs, most often unilaterally after the re-expansion of a lung that had been collapsed for longer than three days. The risk is greater with a large effusion, but this can occur after drainage of a large pneumothorax. It is linked to the generation of increased negative pleural pressure, which can also cause pain or cough. The procedure should therefore be terminated with the onset of cough or chest pain during aspiration or after 3l has been drained.

Peer review

This guideline has been reviewed and approved by the following expert groups:

Emergency Care Institute

Please direct feedback for this procedure to


Hayes-Bradley C, Lewis A, et al. Efficacy of nasal cannula oxygen as a preoxygenation adjunct in emergency airway management. Ann Emerg Med. 2016;68(2):174‐180. doi:10.1016/j.annemergmed.2015.11.012

MacDuff A, Arnold A, Harvey J on behalf of the BTS Pleural Disease Guideline Group. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax. 2010;65:ii18:1131. Available from:

Henry M, Arnold T, Harvey J; Pleural Diseases Group, Standards of Care Committee, British Thoracic Society. BTS guidelines for the management of spontaneous pneumothorax. Thorax. 2003;58 Suppl 2(Suppl 2):ii39-ii52. doi:10.1136/thorax.58.suppl_2.ii39

NSW Agency for Clinical Innovation. Pleural tap/thoracentesis. Sydney: ACI; 2918. Available from:

Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges' clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.

Dunn RJ, Borland M, O’Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.

Huggins JT, Chopra A. Large volume (therapeutic) thoracentesis: Procedure and complications. 2019 Apr. [cited 2019] In UpToDate. Waltham (MA): UpToDate. Available from:

Thomsen TW, DeLaPena J, Setnik GS. Videos in clinical medicine. Thoracentesis. N Engl J Med. 2006;355(15):e16. doi:10.1056/NEJMvcm053812

Puchalski JT, Argento AC, Murphy TE, Araujo KL, Pisani MA. The safety of thoracentesis in patients with uncorrected bleeding risk. Ann Am Thorac Soc. 2013;10(4):336-341. doi:10.1513/AnnalsATS.201210-088OC

Wiederhold BD, Amr O, Modi P, et al. Thoracentesis. [Updated 2020 May 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from:

Laan DV, Vu TD, Thiels CA, Pandian TK, Schiller HJ, Murad MH, Aho JM. Chest wall thickness and decompression failure: A systematic review and meta-analysis comparing anatomic locations in needle thoracostomy. Injury. 2016;47(4):797-804. doi:10.1016/j.injury.2015.11.045.

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

Schildhouse R, Lai A, Barsuk JH, Mourad M, Chopra V. Safe and Effective Bedside Thoracentesis: A Review of the Evidence for Practicing Clinicians. J Hosp Med. 2017;12(4):266-276. doi:10.12788/jhm.2716

Hannan LM, Steinfort DP, Irving LB, Hew M. Direct ultrasound localisation for pleural aspiration: translating evidence into action. Intern Med J. 2014;44(1):50-56. doi:10.1111/imj.12290

© Agency for Clinical Innovation 2021