Trocars and clamps

Trocar or not trocar?

The original chest drain trocars were short stubby daggers through which drains were inserted. Most of us are familiar with sharp tipped trocars which fit inside the tube. Both these outdated types of trocars are dangerous and the Thoracic surgeons cannot countenance their use.

Recently the Portex company have introduced "blunt tipped trocars" (Reference No: 200/801/200,240,280,320 for sizes 20,24,28 and 32 respectively). In experienced hands these have better positioning characteristics and are to be recommended for the positioning of elective drains with the following provisos:

  1. The operator is familiar with both the blunt tipped trocar and the anatomy inside the chest,

  2. A finger has been inserted into the pleura leaving a hole large enough that the drain glides easily,

  3. The drain is never forced.

Clamping Drains

  1. ‘A chest drain has rarely killed anyone because it was left unclamped’. The same cannot be said for a clamped drain which runs the risk of producing a tension pneumothorax.

    Never clamp a chest drain

  1. Even a drain which has not had an air leak can develop a tension pneumothorax on clamping.  It may entrain air around it during inspiration when the ribs open up. If clamped that air cannot get out as the ribs clamp down during expiration. Do not clamp drains to ‘see if they are ready to come out’.


  1. One of the few indications for clamping drains is during transfer of the patient either to or from the bed during which it may be necessary to raise the drain above the level of the patient. Raising the drain risks siphoning the drain contents back into the pleural cavity. It was particularly relevant when carbolic acid was used to disinfect TB in chest drains, though chlorhexidine in the pleural cavity is also rather painful. During transfer one person should take responsibility for the drain during transfer and ideally the drain should be pinched temporarily not clamped.

  2. During bed-side talc pleurodesis (if there is an air leak it should NOT be clamped even during talc pleurodesis)

  3. During removal - clamping prevents drain fluid from siphoning onto the floor.

  4. Following disconnection the treatment is to re-connect the drain. It may be necessary to temporarily clamp the tube till the drain is reconnected. Remember that this can cause a tension pneumothorax so must be temporary only.

    No clamped drain should be left unsupervised

    Drains should not be clamped during transport.