Thoracotomy is indicated in cardiac arrest due to penetrating chest or upper abdominal trauma.
Its purpose is to decompress haemopericardium and to control a cardiac wound.
Traditionally in hospital, a left lateral thoracotomy is perfomed, but the clamshell approach provides better access to and exposure of the organs for the non-expert surgeon such as prehospital emergency medicine clinicians.
The following papers are useful:
How to perform thoracotomy
Emergency thoracotomy: “how to do it.”
Emerg Med J. 2005 Jan 1;22(1):22–4.
Outcomes in London from prehospital thoracotomy
Davies GE, Lockey DJ.
Thirteen Survivors of Prehospital Thoracotomy for Penetrating Trauma: A Prehospital Physician-Performed Resuscitation Procedure That Can Yield Good Results.
The Journal of Trauma: Injury, Infection, and Critical Care. 2011 May;70(5):E75–8.
Clamshell approach versus left lateral
Flaris AN, Simms ER, Prat N, Reynard F, Caillot J-L, Voiglio EJ.
Clamshell incision versus left anterolateral thoracotomy. Which one is faster when performing a resuscitative thoracotomy? The tortoise and the hare revisited.
World J Surg. 2015 May;39(5):1306–11.
This video describes the procedure using a pig model
While the primary purpose of resuscitative thoracotomy is relief of tamponade and control of a cardiac wound, one may find massive intrathoracic haemorrhage rather than tamponade. In the case of unilateral haemorrhage, control may be achieved by the ‘hilar twist’ manoeuvre, which you can read about here