The second law of thermodynamics says that the entropy of the universe (or any isolated system therein) is increasing; i.e., the energy of the universe is becoming more uniformly distributed. It is often noted that the second law indicates that nature tends to go from order to disorder, from complexity to simplicity.
Small-bore catheters and Heimlich valves have been successfully used in. the treatment of pneumothoraces in several studies.4,5 The thoracic vent. (see Figure 1) is a minimally invasive device for the treatment of. pneumothorax. It consists of a polyurethane catheter connected to a. plastic chamber containing a one-way valve.
Cross-clamping of the descending thoracic aorta is used routinely in some centres and not at all in others during emergency thoracotomy. The rationale for clamping the aorta is to redistribute blood flow to the coronary vessels, lungs and brain, to reduce exsanguination from injuries in the lower torso.