Pneumothorax - In a pneumothorax, air collects in the pleural cavity. It may be caused by trauma to the chest, chest surgery, and COPD among other causes. When a pneumothorax is small, it may simply be observed to see if the air is reabsorbed.
This ratio is determined by dividing the HDL cholesterol into the total cholesterol. If a person has a total cholesterol of 200 mg/dL and an HDL cholesterol of 40 mg/dL, his or her total/HDL cholesterol ratio would be 5:1. The goal is to keep this ratio below 5:1, with the ideal being below 3.5:1.his ratio is determined by dividing the HDL cholesterol into the total cholesterol. If a person has a total cholesterol of 200 mg/dL and an HDL cholesterol of 40 mg/dL, his or her total/HDL cholesterol ratio would be 5:1. The goal is to keep this ratio below 5:1, with the ideal being below 3.5:1.
1 Total cholesterol. 2  This is a sum of your blood's cholesterol content. 3  A high level can put you at increased risk of heart disease. 4  Ideally, your total cholesterol should be below 200 milligrams per deciliter (mg/dL), or 5.2 millimoles per liter (mmol/L).