Focus on Acid-Base Balance and Arterial Blood Gases (Relates to Chapter 17, “Fluid, Electrolyte, and Acid-Base Imbalances,” in the textbook) Copyright.
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Focus onFocus onAcid-Base Balance and Acid-Base Balance and Arterial Blood GasesArterial Blood Gases
(Relates to Chapter 17, (Relates to Chapter 17, “Fluid, Electrolyte, and Acid-Base “Fluid, Electrolyte, and Acid-Base
Imbalances,” Imbalances,” in the textbook)in the textbook)
•Maintain a steady balance Maintain a steady balance between acids and bases to between acids and bases to achieve homeostasisachieve homeostasis
•Health problems lead to Health problems lead to imbalanceimbalance•Diabetes mellitusDiabetes mellitus•Vomiting and diarrhea Vomiting and diarrhea •Respiratory conditionsRespiratory conditions
•Measure of HMeasure of H++ ion ion concentrationconcentration
•Blood is slightly alkaline at Blood is slightly alkaline at pH 7.35 to 7.45.pH 7.35 to 7.45.•<7.35 is acidosis.<7.35 is acidosis.•>7.45 is alkalosis.>7.45 is alkalosis.
•Buffers: Act chemically to Buffers: Act chemically to neutralize acids or change neutralize acids or change strong acids to weak acidsstrong acids to weak acids•Primary regulatorsPrimary regulators•React immediatelyReact immediately•Cannot maintain pH without Cannot maintain pH without
adequate respiratory and adequate respiratory and renal functionrenal function
•Respiratory center in medullaRespiratory center in medullacontrols breathing.controls breathing.
•Responds within minutes/hours to Responds within minutes/hours to changes in acid/base.changes in acid/base.
• Increased respirations lead to Increased respirations lead to increasedincreased CO CO22 elimination and elimination and decreased COdecreased CO22 in blood. in blood.
Fig. 17-17. Kinds of acid-base imbalances. A, Respiratory imbalances caused by carbonic acid (CA) excess andcarbonic acid deficit. B, Metabolic imbalances caused by base bicarbonate (BB) deficit and base bicarbonateexcess.
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Respiratory AlkalosisRespiratory Alkalosis
•Carbonic acid deficit caused Carbonic acid deficit caused byby•HyperventilationHyperventilation•Hypoxemia from acute Hypoxemia from acute
pulmonary disorderspulmonary disorders•CompensationCompensation•Rarely occurs because of Rarely occurs because of
aggressive treatment of causes aggressive treatment of causes of hypoxemiaof hypoxemia
•Arterial blood gas (ABG) Arterial blood gas (ABG) values provide information values provide information about about •Acid-base statusAcid-base status•Underlying cause of Underlying cause of
imbalance imbalance •Body’s ability to regulate pHBody’s ability to regulate pH•Overall oxygen statusOverall oxygen status
•pH 7.36pH 7.36•PaCOPaCO22 67 mm Hg 67 mm Hg•PaOPaO22 47 mm Hg 47 mm Hg•HCOHCO33 37 mEq/L 37 mEq/L•What is this?What is this?•Respiratory acidosisRespiratory acidosis
A patient with an acid-base imbalance has an A patient with an acid-base imbalance has an altered altered
potassium level. The nurse recognizes that the potassium level. The nurse recognizes that the potassium potassium
level is altered because:level is altered because:
1. Potassium is returned to extracellular fluid 1. Potassium is returned to extracellular fluid when metabolic acidosis is corrected.when metabolic acidosis is corrected.
2. Hyperkalemia causes an alkalosis that results in 2. Hyperkalemia causes an alkalosis that results in potassium being shifted into the cells.potassium being shifted into the cells.
3. Acidosis causes hydrogen ions in the blood to 3. Acidosis causes hydrogen ions in the blood to be exchanged for potassium from the cells.be exchanged for potassium from the cells.
4. In alkalosis, potassium is shifted into 4. In alkalosis, potassium is shifted into extracellular fluid to bind excessive bicarbonate.extracellular fluid to bind excessive bicarbonate.
A patient has the following arterial blood A patient has the following arterial blood gas (ABG) results: pH 7.48, PaOgas (ABG) results: pH 7.48, PaO22 86 mm 86 mm Hg, PaCOHg, PaCO22 44 mm Hg, HCO 44 mm Hg, HCO33 29 mEq/L. 29 mEq/L. When assessing the patient, the nurse When assessing the patient, the nurse would expect the patient to experience:would expect the patient to experience:
1. Warm, flushed skin.1. Warm, flushed skin. 2. Respiratory rate of 36.2. Respiratory rate of 36.3. Blood pressure of 94/52.3. Blood pressure of 94/52.4. Hypertonic muscles with cramping.4. Hypertonic muscles with cramping.
•History of nausea and History of nausea and vomiting for the past weekvomiting for the past week
•Has been self-medicating Has been self-medicating himself with baking soda to himself with baking soda to control his abdominal control his abdominal discomfortdiscomfort
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.
1.1. Describe a patient who Describe a patient who would have these ABGs, would have these ABGs, including history and including history and assessment.assessment.