2. Acid-Base Balance Homeostasis & optimal cellular function Hydrogen ion concentration of body fluids wnl Hydrogen ion concentration falls pH rises solution become more alkaline or basic
3.
4. Acid-Base Disorders Hydrogen ions (H+) determines acidity of body fluids Acids release H+ ions in solution Bases accepts H+ ions in solution
5. Acid-Base Disorders H+ ions concentration of a solution is measured by its pH Normal pH 7.35-7.45 (pH of 7 is neutral)
59. Normal range BE is -2 to +2 BE of -8 represents a deficit of base=metabolic acidosis BE of +10 representsan excess of base=metabolic alkalosis
60. Metabolic Acidosis Deficit HCO3 Common in cases of kidney disease and diabetes Respiratory Acidosis Excess HCO3 Caused by hypoventilation Metabolic Alkalosis Excess HCO3 Caused by diarrhea, steroid or diuretic therapy. Respiratory Alkalosis Deficit HCO3 Caused by hyperventilation Acid-Base Imbalances
77. Compensation When there is an imbalance in one parameter of the buffer system (bicarbonate-kidneys) – carbonic acid (lungs) the other tries to compensate for it by causing the opposite imbalance Goal: Restore the 20:1 ratio & return the pH back to the acceptable range 7.35-7.45
78. ABG Interpretation: Final Step Determine if compensation is present and to what extent When compensation is present, you will see two imbalances The question-Which is the primary problem & which imbalance is due to compensation
79. Compensation The Clue: pH If the pH is leaning toward acidosis or alkalosis then the parameter with the matching imbalance is the primary problem & the other is due to compensation
80. Compensation: Example Pt has chronic pulmonary problems & is in a chronic respiratory acidosis. His kidneys will compensate by retaining bicarbonate Creating a metabolic alkalosis to balance his chronic respiratory acidosis
81. Compensation pH 7.30 acidosis PCO2 70 respiratory acidosis HCO3 30 mild metabolic alkalosis Interpretation Respiratory acidosis with partial compensation by the kidneys. The kidneys have only begun to compensate, because the pH is not back to acceptable limits yet
82. Supplementary Resources Handout: “Interpreting Arterial Blood Gases” Nursing Article ”Perfecting your acid-base balancing act: How to detect and correct acid-base disorders”
93. Mrs. Mendoza Which assessment data indicate that this client has impaired gas exchange? 75-years-old H/O emphysema Adm with Pneumonia Decreased urine output Lethargy Decreased chest excursion hypotension
94. Mrs. Mendoza Which of the following ABG values indicates that this client is a CO2 retainer? PaCO2 = 40 mm Hg PaCO2 = 60 mm Hg Bicarbonate = 42 PaO2 = 60 mm Hg
95. Mrs. Mendoza Which of the following ABGs most likely indicate that she is having a negative response to the administration of oxygen. (next slide) Baseline ABG’s pH 7.36 PaCO2 60 mm Hg Pa02 52 mmHg Bicarbonate 42 mEq/L
112. Mrs Mendoza Later in the shift, you note that his oxygen is set at 5 L/minute. The client says that he asked the nursing assistant to turn up his oxygen because he was havng trouble breathing. What actions, if any, should you take at this time
113. Mr. Henderson: H/O Cellulites What is the patients acid base imbalance? T 101 F 90/60 SOB Diarrhea 2 days pH 7.30 pCO2 28 Pa02 88 HCO3 17
123. A patient is admitted with the diagnosis of diabetic ketoacidosis. The nurse realizes that this patient’s body will attempt to attain acid-base balance by:
124. Decreasing its respiratory rate. Increasing the reabsorption of hydrogen ions. Increasing the secretion of hydrogen ions. Decreasing the reabsorption of bicarbonate.
125. A patient has a respiratory rate of 20. The nurse calculates this patient’s minute ventilation to be:
127. The nurse, admitting a patient with diabetes, believes the patient is attempting to correct an acidotic condition. Which of the following did this nurse most likely observe while assessing this patient?
128. Slow methodical respirations Deep rapid respirations Change in level of consciousness Intact extraocular movements
129. The nurse is caring for a patient with metabolic acidosis. The nurse realizes that which of the following laboratory values might be altered for this patient?
133. The nurse is caring for a patient with pneumonia who has arterial blood gas values of: pH 7.20, PaCO2 75, HCO3- 28, PaO2 44. Which of the following would be a priority for this patient?
134. Assisting the patient to breathe into a paper bag. Preparing to administer Sodium Bicarbonate IV. Placement of the patient in high Fowler’s position. Administration of the prn sedative available.
135. A patient is admitted in respiratory acidosis secondary to barbiturate overdose. Which of the following will the nurse most likely assess in this patient?
137. The nurse is providing discharge instructions to a patient with respiratory alkalosis. Which of the following statements indicates the patient understands the instructions?
138. “I will not take my Lasix without a potassium supplement.” “I will not use Mylanta 5-6 times a day like I used to.” “I will take a stress management class or seek counseling.” “I will call my MD the next time I have diarrhea for a few days.”
Editor's Notes
Metabolic alkalosis
Decreased chest excursion
40 mm Hg
Resp acidosis
#4
Uncompensated because the pH is below normal levels. Interventions maintain airway, enhance gas exchange including drug therapy to open airways and to treat pna, ox therapy, pulmonary hygiene-positioning and breathing techniques, ventilatory support, prevention of complications
Keeping in mind that the only respiratory trigger for clients with COPD to breathe is a decreased arterial oxygen level, you should immediately reduce the o2 to the ordered amount, assess LOC, pulse ox, breath sounds and other resp assessments. Instruct the client to notify you if he has difficulty breathing and explain the rationale for leaving the oxygen at low levels of delivery
Metabolic acidosis
Overelimination of HCO3 (metabolic alkalosis)
Administer fluids
Serum potassium levels are often elevated as a result of the body’s attempt to maintain electronneutrality during buffering. As hydrogen ions move into the cells potassium ions move out to balance the intracellular charge. As a result the extracellular potassium levels increase, causing hyperkalemia. Blood glucose should be monitored to ensure that diabetic ketoacidosis is not contributing to the client’s acidotic condition. Continue to monitor ABGs and PaCO2 level
