ABG Analysis NCLEX Exam #3
In acid-base balance the normal plasma PCO2 and bicarbonate levels are disturbed. Match the changes in these parameters given below with the disorders in the drop down list. Low plasma PaCO2
Excessive pulmonary ventilation decreases hydrogen ion concentration and thus causes respiratory alkalosis. It can become dangerous when it leads to cardiac dysrhythmias caused partly by a decrease in serum potassium levels.
High plasma PaCO2
An excess of carbon dioxide (hypercapnia) can cause carbon dioxide narcosis. In this condition, carbon dioxide levels are so high that they no longer stimulate respirations but depress them.
Decreased plasma bicarbonate (HCO3-)
The body compensates by using body fat for energy, producing abnormal amounts of ketone bodies. In an effort to neutralize the ketones and maintain the acid-base balance of the body, plasma bicarbonate is exhausted. This condition can develop in anyone who does not eat an adequate diet and whose body fat must be burned for energy. Symptoms include headache and mental dullness.
Increased plasma bicarbonate (HCO3-)
In metabolic alkalosis, breathing becomes depressed in an effort to conserve carbon dioxide for combination with water in the blood to raise the blood level of carbonic acid. Symptoms include confusion, dizziness, numbness or tingling of fingers or toes.
What two organs in the body serve as a compensatory function to maintain acid base balance?
The carbonic acid concentration is controlled by the amount of carbon dioxide excreted by the lungs. The bicarbonate concentration is controlled by the kidneys, which selectively retain or excrete bicarbonate in response to the body’s needs.
Arterial blood gas (ABG) measurement will give the information needed to determine if the primary disturbance of acid-base balance is respiratory or metabolic in nature.
ABG’s are blood tests that are useful in identifying the cause and extent of the acid-base disturbance and in guiding and monitoring treatment.
The major effect of acidosis is overexcitement of the central nervous system.
The major effect is a depression of the central nervous system, as evidenced by disorientation followed by coma.
Alkalosis is characterized by overexcitement of the nervous system.
The muscles may go into a state of tetany and convulsions.
The human body functions optimally in a state of homeostasis.
The maintenance of acid-base balance, which in one part of homeostasis, is evidenced by an arterial plasma pH value of 7.35-7.45. Many mechanisms in the body work together to achieve and maintain this delicate narrow range of pH that is essential for normal cell function.
Acids have no hydrogen ions and are able to bind in a solution.
Acids are substances having one or more hydrogen ions that can be liberated into a solution. Bases are substances that can bind hydrogen ions in a solution.
Match the acid-base status of the following blood samples to the disorders in the drop down list. (PaCO2 values are in mm Hg and bicarbonate values in mmol/l). pH 7.57, PaCO2 22, HCO3- 17
pH 7.39, PaCO2 44, HCO3- 26
pH 7.55, PaCO2 25, HCO3- 22
pH 7.17, PaCO2 48, HCO3- 36
pH 7.34, PaCO2 24, HCO3- 20
pH 7.64, PaCO2 25, HCO3- 19
pH 7.45, PaCO2 50, HCO3- 30
pH 7.6, PaCO2 53, HCO3- 38
pH 7.5, PaCO2 19, HCO3- 22
pH 7.4, PaCO2 59, HCO3- 35
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