Inserting a Chest Drain
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The Safe Triangle

The Safe Triangle for chest drain insertion
The Safe Triangle for chest drain insertion

The safe triangle is an anatomical space created by:

  • Mid-axillary line / boarder of latissimus dorsi
  • Lateral boarder of pec major
  • Imaginary horizontal line from the nipple
And the drain is usually inserted in the 4th, 5th, or 6th intercostal space

The Procedure

  • Find a location in the safe triangle
  • Alternate locations include 2nd intercostal space mid-clavicular line, and 7th intercostal space, posteriorly, but these are less comfortable for the patient.
  • Using 10-20ml 1% lidocaine inject down at the pleural level, just above the rib (to avoid the neurovascular bundle), usually the 6th rib
  • Then attempt to aspirate air of fluid – if you cant, then don’t insert the drain here! Wait 3 minutes, and try again
  • Then blunt dissect down to the level of the pleura (e.g. using scissors, using the opening action of the scissors to dissect, or using forceps)
  • Puncture the pleura with scissors or forceps
  • If you are using a large bore tube, you may need to insert a finger into your dissect to remove any adherent lung
  • Remove the metal part of the drip before inserting – you should already have done your dissection – don’t force it in!
  • Advance the drain slowly, using forceps if necessary. Stop if you hit serious resistance
  • Attached the other end of the drain to the underwater seal
    • The long tube should be under the water, and should bubble with respiration
  • Medium and large bore tubes may require suturing around the entry site
  • Fix the chest drain in place with a tie around the tube
  • Request CXR to ensure the drain has been placed correctly

Clamping a chest drain

  • This is occasionally performed in the case of pleural effusion, to control the rate of drainage, as draining too fast can result in expansion pulmonary oedema.
  • You should never clamp a chest drain in the case of pneumothorax


  • Trauma / injury to thoracic / abdominal organs
  • Trauma to the long thoracic nerve of bell resulting in wing scapula
  • Arrhythmia (rare)

Things to watch out for

  • Backwards flow of water seal towards chest cavity
  • Prolonged bubbling of the chest drain fluid
  • Blockage of the tube due to kinks, blood clot / other. There will be no ‘swinging’ or ‘bubbling’ in the seal fluid
  • Wrongly positioned chest drain – check the CXR

Removing the tube

  • Check there is re-expansion on CXR
  • In pleural effusion you may want to clamp the drain, as you may want to re-insert it
  • In pneumothorax, clamping is not necessary as reinsertion is unlikely
  • Give the patient a strong analgesic (e.g. morphine)
  • Remove the tube during expiration, and suture the insertion site


  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

Read more about our sources

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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