C H A P T E R 9 Acid-Base Balance: From Saunders Comprehensive Review for the NCLEX-RN Examination 8th Edition. (Available: https://bit.ly/2HeJuMt ). Contains Practice questions and Answers with the Rationale, Test-Taking Strategy, Level of Cognitive Ability, Client Needs, Integrated Process, Content Area, Health Problem, Priority Concepts and Reference

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Priority Concepts Acid-Base Balance; Oxygenation I. Hydrogen Ions, Acids, and Bases A. Hydrogen ions 1. Vital to life because hydrogen ions determine the pH of the body, which must be maintained ... in a narrow range 2. Expressed as pH; the pH scale is determined by the number of hydrogen ions and goes from 1 to 14; 7 is considered neutral. 3. The number of hydrogen ions in the body fluid determines whether it is acid (acidosis), alkaline (alkalosis), or neutral. 4. The pH of body fluid is between 7.35 and 7.45. B. Acids 1. Produced as end products of metabolism 2. Contain hydrogen ions 3. Are hydrogen ion donors; they give up hydrogen ions to neutralize or decrease the strength of an acid or to form a weaker base. C. Bases 1. Contain no hydrogen ions 2. Are hydrogen ion acceptors; they accept hydrogen+ ions from acids to neutralize or decrease the strength of a base or to form a weaker acid. 3. Normal serum levels of bicarbonate (HCO3–) are 21 to 28 mEq/L (21 to 28 mmol/L). II. Regulatory Systems for Hydrogen Ion Concentration in the Blood A. Buffers 1. Buffers are the fastest-acting regulatory system. 2. Buffers provide immediate protection against changes in hydrogen ion concentration in the extracellular fluid. 3. Buffers are reactors that function only to keep the pH within the narrow limits of stability when too much 273acid or base is released into the system, and buffers absorb or release hydrogen ions as needed. 4. Buffers serve as a transport mechanism that carries excess hydrogen ions to the lungs. 5. Once the primary buffer systems react, they are consumed, leaving the body less able to withstand further stress until the buffers are replaced. The underlying cause of an acid-base imbalance needs to be identified and the cause needs to be treated to resolve the imbalance. B. Primary buffer systems in extracellular fluid 1. Hemoglobin system a. System maintains acid-base balance by a process called chloride shift. b. Chloride shifts in and out of the cells in response to the level of oxygen (O2) in the blood. c. For each chloride ion that leaves a red blood cell, a bicarbonate ion enters. d. For each chloride ion that enters a red blood cell, a bicarbonate ion leaves. 2. Plasma protein system a. The system functions along with the liver to vary the amount of hydrogen ions in the chemical structure of plasma proteins. b. Plasma proteins have the ability to attract or release hydrogen ions. 3. Carbonic acid–bicarbonate system a. Primary buffer system in the body b. The system maintains a pH of 7.4 with a ratio of 20 parts bicarbonate ( ) to 1 part carbonic acid (H2CO3) (Fig. 9-1). c. This ratio (20:1) determines the hydrogen ion concentration of body fluid. d. Carbonic acid concentration is controlled by the excretion of CO2 by the lungs; the rate and depth of respiration change in response to changes in the CO2. e. The kidneys control the bicarbonate concentration and selectively retain or excrete bicarbonate in response to bodily needs. 2744. Phosphate buffer system a. System is present in cells and body fluids and is especially active in the kidneys. b. System acts like bicarbonate and neutralizes excess hydrogen ions. C. Lungs 1. The lungs are the second defense of the body; they interact with the buffer system to maintain acid-base balance. 2. During acidosis, the pH decreases and the respiratory rate and depth increase in an attempt to exhale acids. The carbonic acid created by the neutralizing action of bicarbonate can be carried to the lungs, where it is reduced to CO2 and water and is exhaled; thus, hydrogen ions are inactivated and exhaled. 3. During alkalosis, the pH increases and the respiratory rate and depth decrease; CO2 is retained and carbonic acid increases to neutralize and decrease the strength of excess bicarbonate. 4. The action of the lungs is reversible in controlling an excess or deficit. 5. The lungs can hold hydrogen ions until the deficit is corrected or can inactivate hydrogen ions, changing the ions to water molecules to be exhaled along with CO2, thus correcting the excess. 6. The process of correcting a deficit or excess takes 10 to 30 seconds to complete. 7. The lungs are capable of inactivating only hydrogen ions carried by carbonic acid; excess hydrogen ions created by other mechanisms must be excreted by the kidneys. Monitor the client’s respiratory status closely. During acidosis, the respiratory rate and depth increase in an attempt to exhale acids. During alkalosis, the respiratory rate and depth decrease; CO2 is retained to neutralize and decrease the strength of excess bicarbonate. D. Kidneys 1. The kidneys provide a more inclusive corrective response to acid-base disturbances than other corrective mechanisms, even though the renal excretion of acids and alkalis occurs more slowly. 2. Compensation requires a few hours to several days; 275 Practice Questions 54. The nurse reviews the arterial blood gas results of a client and notes the following: pH 7.45, Paco2 of 30 mm Hg (30 mm Hg), and HCO3– of 20 mEq/L (20 mmol/L). The nurse analyzes these results as indicating which condition? 1. Metabolic acidosis, compensated 2. Respiratory alkalosis, compensated 3. Metabolic alkalosis, uncompensated 4. Respiratory acidosis, uncompensated 55. The nurse is caring for a client with a nasogastric tube that is attached to low suction. The nurse monitors the client for manifestations of which disorder that the client is at risk for? 1. Metabolic acidosis 2. Metabolic alkalosis 3. Respiratory acidosis 4. Respiratory alkalosis 56. A client with a 3-day history of nausea and vomiting presents to the emergency department. The client is hypoventilating and has a respiratory rate of 10 breaths per minute. The electrocardiogram (ECG) monitor displays tachycardia, with a heart rate of 120 beats per minute. Arterial blood gases are drawn and the nurse reviews the results, expecting to note which finding? 1. A decreased pH and an increased Paco2 2. An increased pH and a decreased Paco2 3. A decreased pH and a decreased HCO3– 4. An increased pH and an increased HCO3– 57. The nurse is caring for a client having respiratory distress related to an anxiety attack. Recent arterial blood gas values are pH = 7.53, Pao2 = 72 mm Hg (72 mm Hg), Paco2 = 32 mm Hg (32 mm Hg), and = 28 mEq/L (28 mmol/L). Which conclusion about the client should the nurse make? 1. The client has acidotic blood. 2. The client is probably overreacting. 3. The client is fluid volume overloaded. 4. The client is probably hyperventilating. 58. The nurse is caring for a client with diabetic ketoacidosis and documents that the client is experiencing Kussmaul’s respirations. Which patterns did the nurse observe? Select all that apply. 1. Respirations that are shallow 2. Respirations that are increased in rate 2883. Respirations that are abnormally slow 4. Respirations that are abnormally deep 5. Respirations that cease for several seconds 59. A client who is found unresponsive has arterial blood gases drawn and the results indicate the following: pH is 7.12, Paco2 is 90 mm Hg (90 mm Hg), and is 22 mEq/L (22 mmol/L). The nurse interprets the results as indicating which condition? 1. Metabolic acidosis with compensation 2. Respiratory acidosis with compensation 3. Metabolic acidosis without compensation 4. Respiratory acidosis without compensation 60. The nurse notes that a client’s arterial blood gas (ABG) results reveal a pH of 7.50 and a Paco2 of 30 mm Hg (30 mm Hg). The nurse monitors the client for which clinical manifestations associated with these ABG results? Select all that apply. 1. Nausea 2. Confusion 3. Bradypnea 4. Tachycardia 5. Hyperkalemia 6. Lightheadedness 61. The nurse reviews the blood gas results of a client with atelectasis. The nurse analyzes the results and determines that the client is experiencing respiratory acidosis. Which result validates the nurse’s findings? 1. pH 7.25, Paco2 50 mm Hg (50 mm Hg) 2. pH 7.35, Paco2 40 mm Hg (40 mm Hg) 3. pH 7.50, Paco2 52 mm Hg (52 mm Hg) 4. pH 7.52, Paco2 28 mm Hg (28 mm Hg) 62. The nurse is caring for a client who is on a mechanical ventilator. Blood gas results indicate a pH of 7.50 and a Paco2 of 30 mm Hg (30 mm Hg). The nurse has determined that the client is experiencing respiratory alkalosis. Which laboratory value would most likely be noted in this condition? 1. Sodium level of 145 mEq/L (145 mmol/L) 2. Potassium level of 3.0 mEq/L (3.0 mmol/L) 3. Magnesium level of 1.8 (0.74 mmol/L) 4. Phosphorus level of 3.0 mg/dL (0.97 mmol/L) 63. The nurse is caring for a client with several broken ribs. The client is most likely to experience what type of acid-base imbalance? 1. Respiratory acidosis from inadequate ventilation 2. Respiratory alkalosis from anxiety and hyperventilation 3. Metabolic acidosis from calcium loss due to broken bones 4. Metabolic alkalosis from taking analgesics containing bas [Show More]

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