Enfemeria

Course Contents

Purpose/Goals Objectives Introduction ABG Interpretation Respiratory Acidosis Respiratory Alkalosis Metabolic Acidosis

Metabolic Alkalosis Systematically reviewing the pH, HCO3, and PaCO2 Role of ABG in Trauma Assessment Conclusion References

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Purpose/Goals
The purpose of this coursewill be to remove the mystery behind the interpretation of the arterial blood gases (ABG); raise awareness and understanding of the various aspects of the ABG, and provide a comfort level with care of the patient by increasing the knowledge base.

Objectives
After completion of this course, the learner will: Demonstrate the ability to distinguish between acidosis and alkalosis Interpret ABGresults Discuss the causes of respiratory acidosis and alkalosis Discuss the causes of metabolic acidosis and alkalosis Identify the role of the ABG in a trauma assessment

Introduction
Understanding the significance of the findings for the arterial blood gases (ABG) is the first step in interpretation of them. Without this understanding, the nurse cannot be expected to realize the implication of theresults.

A study conducted in Illinois at Freeport Health Network Memorial Hospital and Swedish American Hospital demonstrated that a computer based module aided nurses to learn ABG interpretation (Schneiderman, Corbridge, & Zerwic, 2009). Many adult students demonstrate various methods of learning to better enhance their knowledge base. Finding the best education method for the individual isthe first step to success in clinical competence. Whatever the underlying cause for the acid-base disturbance, one must gain knowledge for interpretation of the ABG to establish the best course of treatment. Therefore, the healthcare provider will determine the limitations of therapy based on the results of the ABG (Kellum, 2007).

ABG Interpretation
When interpreting the ABG results, one mustfirst know the five major components of the ABG to be addressed: oxygen saturation (SaO2), partial pressure of oxygen (PaO2), acidity or alkalinity (pH), partial pressure of carbon dioxide (PaCO2), and bicarbonate ions concentration (HCO3) (Pruitt & Jacobs, 2004). Let us begin by looking at the pH of the blood. The acid-base balance of the blood is maintained by two areas of the body: therespirations and the kidneys. The lower pH represents acidosis and the higher pH represents alkalosis. The normal range is 7.35-7.45 mm Hg. The PaO2 evaluates the oxygen in plasma and has a normal range of 80-95 mm Hg. This does not measure the amount of oxygen attached to the hemoglobin. SaO2 measures the amount of oxygen attached to the hemoglobin. The normal range is 95-99% and should be above 90%.PaCO2 evaluates the ventilation component. The normal range is 35-45. However, the value is inversely related to ventilation. For example, decreased ventilation has a higher value and increased ventilation has a lower value. Therefore, hyperventilation causes alkalosis because the patient is blowing off carbon dioxide and hypoventilation causes acidosis because the patient is retaining carbondioxide. The body adjusts for these conditions by changing the respiratory rate (Pruitt & Jacobs, 2004). HCO3 is regulated by the kidneys and evaluates the metabolic component. The normal range is 22-26 mEq/L. Below 22 is considered to be acidosis and above 26 is alkalosis. The body can adjust to the abnormalities in the HCO3 levels but not as quickly as it can to the abnormal PaCO2 levels. Several dayscould be required to make the necessary adjustments to bring the HCO3 levels to a normal range (Pruitt & Jacobs, 2004).

Test
pH HCO3 PaCO2 PaO2 SaO2

Normal Value
7.35-7.45 22-26 35-45 80-95 mm Hg 95-99%

Four conditions are evaluated based on the ABGs: respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis. As we explore these conditions, the...