Question

Sean crashed on his mountain bike while descending one of the ski runs at Ski Bowl. When the paramedics found him Sean complained of a sharp, stabbing pain in his right pectoral and axillary regions. He also feltout of breath and his heart rate and breathing rate increased dramatically. Sean was transported to the emergency room. The physician on call listened to John’s breathing and ordered a chest X-ray and blood gas test. After viewing the test results, the physician informed John that hehad pneumothorax, probably induced by blunt trauma and a broken rib suffered in the crash.The doctor told John that since his pneumothorax was small, it should heal on its own; however, Sean should avoid high altitudes, flying in non-pressurized airplanes, and scuba diving.

1. What is pneumothorax and why would it occur?

2. How does pneumothorax relate to the pleural cavity and interpleural pressure? Why?

3. Why would pneumothorax cause Sean’s symptoms?

4. What would the blood gas test have revealed and why? What about the chest X-ray?

5. Why was John told to avoid high altitudes and non-pressurized airplanes? What about scuba diving?

Answer 1

1. Pneumothorax means a collapsed lung. This occurs when air gets into the space between the lungs and the chest wall, exerting pressure from outside on the lungs and preventing its proper expansion during inhalation. There are several causes for pneumothorax to occur but for Sean, it is due to the blunt and penetrating chest injury [due to the broken rib] that he has suffered.

2. The mechanism of inhalation and exhalation is controlled by the movement of the diaphragm and the ribs which helps to increase and decrease the volume of the chest cavity and controlling the pressure within the chest cavity. Under normal conditions, when the diaphragm moves down, the rib cage moves outwards. The chest cavity expands, the air pressure within the chest cavity reduces in comparison to the atmospheric pressure and air rushes into the lungs through the nostrils. This is inhalation.

Next, the diaphragm moves back to its original position, the rib cage moves inwards and the volume of chest cavity reduces, pushing the air out of the lungs. This is inhalation.

If air leaks into the chest cavity, this balance of pressure is disturbed and the inhalation and exhalation of air does not take properly.

3. Since the lungs have collapsed and they are not able to expand due to the air pressure from outside on their walls, enough air is not being inhaled by Sean. This is why he is feeling breathless. Because enough air is not reaching his lungs, the breathing rate has increased. The heart rate has increased to increase the blood supply to the cells so that they do not starve of oxygen.

4. The blood gas test would have revealed an increase in CO2 level and a below normal O2 level. This is because the breathing is being hindered due to pneumothorax and proper inhalation and exhalation is not taking place.

The chest X-ray will show the broken rib and how much it has penetrated into the chest cavity.

5. High altitudes have a lower density of air. Sean has been told to avoid high altitudes and non-pressurized airplanes because it will make his symptoms worsen as the amount of oxygen reaching his body will be even lesser. He will suffer from more intense breathlessness.

The same conditions will apply in scuba diving as lesser air will extend more pressure on his already stressed lungs and increase the symptoms he is suffering from.