The case of \"I can't catch my breath\"

John, a healthy twenty-eight year old electrical engineer, wasdriving home from work one evening when he experienced suddenstabbing pain in his right pectoral and right lateral axillaryregions. He began to feel out of breath and both his respiratoryrate and heart rate increased dramatically. As luck would have it,John passed a hospital each day on his way home and was able to gethimself to the hospital’s emergency room. The emergency roomphysician listened to John’s breathing with a stethoscope andrequested blood gas analysis and a chest x-ray. John answered a fewof the doctor’s questions. The doctor noted that John had nohistory of respiratory problems but was a heavy smoker.

After viewing the chest radiograph, the doctor informed Johnthat he had experienced a spontaneous pneumothorax, or what iscommonly called a collapsed lung. The doctor explained that a holehad opened in John’s right lung and that this hole had allowed airto leak into the cavity surrounding the lung. Then, as a result ofthe lung’s own elastic nature, the lung had collapsed. The doctorsaid he could not be certain of the cause of the pneumothorax, butsmoking cigarettes had certainly increased the likelihood of ithappening. He told John he was fortunate the pneumothorax wassmall, which meant that relatively little air had escaped from thelung into the surrounding cavity, and it should heal on its own. Heinstructed John to quit smoking, avoid high altitudes, flying innon pressurized aircraft, and scuba diving. He also had John makean appointment for a re-check and another chest x-ray.

Case Background

Spontaneous pneumothorax occurs when a blister on the surface ofthe lung opens, allowing air from the lung to move into the pleuralcavity. This occurs because alveolar pressure is normally greaterthan the pressure in the pleural cavity. As air escapes from thelung, the lung tissues will recoil, and the lung will begin tocollapse. The lung will continue to collapse until the differencebetween the alveolar pressure and pleural pressure disappears oruntil the collapsing of the lung causes the opening to seal.

The pneumothorax decreases the efficiency of the respiratorysystem, which in turn results in decreased blood oxygenconcentration, increased respiratory rate, and increased heartrate. If the pneumothorax is small, the air that escapes into thepleural cavity can be reabsorbed into the lung once the opening hassealed shut. If the pneumothorax is large, a needle or chest tubemay have to be inserted into the pleural cavity to draw the air outand allow for the re expansion of the lung.

Utilizing the med terms you learned this week answerthe following questions

Why was John instructed to avoid high altitudes andflying in non pressurized aircraft?

That is, what are the effects of high altitudes on the respiratorysystem?