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RN ADULT MEDICAL SURGICAL NURSING CHAPTER 45 Acid‑BAse imBAlAnces 281
UNIT 6 NURSING CARE OF CLIENTS WHO HAVE FLUID/
ELECTROLYTE/ACID‑BASE IMBALANCES
CHAPTER 45 Acid‑Base
Imbalances
For cells to function optimally, metabolic
processes must maintain a steady balance
between the acids and bases found in the body.
Acid‑base balance represents homeostasis of
hydrogen (H+) ion concentration in body fluids.
Hydrogen shifts between the extracellular and
intracellular compartments to compensate
for acid‑base imbalances. minor changes in
hydrogen concentration have major effects on
normal cellular function.
Arterial pH is an indirect measurement of
hydrogen ion concentration and is a result of
respiratory and kidney compensation function.
Arterial blood gases (ABGs) are most commonly
used to evaluate acid‑base balance. The pH is
the expression of the balance between carbon
dioxide (cO 2 ), which is regulated by the lungs,
and bicarbonate (HcO 3 ‑), a base regulated by
the kidneys. The greater the concentration of
hydrogen, the more acidic the body fluids and
the lower the pH. The lower the concentration of
hydrogen, the more alkaline the body fluids and
the higher the pH.
MAINTENANCE OF ACID‑BASE BALANCE
Acid‑base balance is maintained by chemical, respiratory, and kidney function.
Chemical (bicarbonate and intracellular fluid) and protein buffers (albumin and globulins) ● (^) First line of defense ● (^) Either bind or release hydrogen ions as needed ● (^) Respond quickly to changes in pH
Respiratory buffers ● (^) Second line of defense ● (^) Control the level of hydrogen ions in the blood through the control of CO 2 levels ● (^) When a chemoreceptor senses a change in the level of CO 2 , a signal is sent to the brain to alter the rate and depth of respirations. ◯ (^) Hyperventilation: Decrease in hydrogen ions (helps to blow of excess hydrogen ions) ◯ (^) Hypoventilation: Increase in hydrogen ions
Kidney buffers ● (^) Kidneys are the third line of defense. ● (^) This buffering system is much slower to respond, but it is the most effective buffering system with the longest duration. ● (^) Kidneys control the movement of bicarbonate in the urine. Bicarbonate can be reabsorbed into the bloodstream or excreted in the urine in response to blood levels of hydrogen. ● (^) Kidneys can also produce more bicarbonate when needed. ◯ (^) High hydrogen ions: Bicarbonate reabsorption and production ◯ (^) Low hydrogen ions: Bicarbonate excretion
cOmPensATiOn
Compensation refers to the process by which the body attempts to correct changes and imbalances in pH levels. ● (^) Full compensation occurs when the pH level of the blood returns to normal (7.35 to 7.45). ● (^) If the pH level is not able to normalize, it is referred to as partial compensation.
CHAPTER 45
45.1 Insufficient compensation
Respiratory compensation Metabolic compensation
H 2 O + CO 2 H 2 CO 3 H+^ + HCO 3 ‑
Water carbon dioxide
carbonic acid
Hydrogen ion
Bicarbonate
expelled by lungs expelled by kidneys
282 CHAPTER 45 Acid‑BAse imBAlAnces CONTENT MASTERY SERIES
eXAmPles ● (^) Metabolic alkalosis, metabolic acidosis, respiratory alkalosis, and respiratory acidosis are examples of acid‑base imbalances. ● (^) Acid‑base imbalances are a result of insufficient compensation. Respiratory and kidney function play a large role in the body’s ability to effectively compensate for acid‑base alterations. Organ dysfunction negatively affects acid‑base compensation. (45.1)
HEALTH PROMOTION AND DISEASE PREVENTION ● (^) Encourage a healthy diet and physical activity. ● (^) Limit the consumption of alcohol. ● (^) Encourage drinking six to eight cups of water daily. ● (^) Maintain an appropriate weight for height and body frame. ● (^) Promote smoking cessation.
ASSESSMENT
RisK FAcTORs
Respiratory acidosis: Hypoventilation
RESULTS FROM
● (^) Respiratory depression from opioids, poisons, anesthetics ● (^) Clients who have brain tumors, cerebral aneurysm, stroke or overhydration, trauma, or neurological diseases (myasthenia gravis, Guillain‑Barré when respiratory effort is affected) ● (^) Inadequate chest expansion due to muscle weakness, pneumothorax/hemothorax, flail chest, obesity, sleep apnea, tumors, or deformities ● (^) Airway obstruction that occurs in from neck edema, or localized lymph node enlargement, foreign bodies or mucus ● (^) Alveolar‑capillary blockage secondary to a pulmonary embolus, thrombus, acute respiratory distress syndrome, chest trauma, drowning, or pulmonary edema ● (^) Inadequate mechanical ventilation
RESULTS IN
● (^) Increased CO (^2) ● (^) Increased or normal H+^ concentration
MANIFESTATIONS
● (^) Vital signs: Tachycardia (severe acidosis can lead to bradycardia), tachypnea, increased blood pressure ● (^) Dysrhythmias: Ventricular fibrillation can be the first indication in a client receiving anesthesia. ● (^) Neurological: Anxiety, irritability, confusion, coma ● (^) Respiratory: Ineffective, shallow, rapid breathing ● (^) Skin: Pale or cyanotic ● (^) Chronic respiratory acidosis can be seen in clients who have pulmonary disease, sleep apnea, and obesity.
NURSING CARE: Oxygen therapy, maintain patent
airway, and enhance gas exchange (positioning and breathing techniques, ventilatory support, bronchodilators, mucolytics).
Respiratory alkalosis: Hyperventilation
RESULTS FROM
● (^) Hyperventilation due to fear, anxiety, intracerebral trauma, salicylate toxicity, or excessive mechanical ventilation. ● (^) Hypoxemia from asphyxiation, high altitudes, shock, or early‑stage asthma or pneumonia.
RESULTS IN
● (^) Decreased CO (^2) ● (^) Decreased or normal H+^ concentration
MANIFESTATIONS
● (^) Vital signs: Tachypnea ● (^) Neurological: Inability to concentrate, numbness, tingling, tinnitus, and possible loss of consciousness ● (^) Cardiovascular: Tachycardia, ventricular, and atrial dysrhythmias ● (^) Respiratory: Rapid, deep respirations
NURSING CARE: Oxygen therapy, anxiety reduction
interventions, and rebreathing techniques
Metabolic acidosis
RESULTS FROM
● (^) Excess production of hydrogen ions ● (^) Diabetic ketoacidosis (DKA) ● (^) Starvation ● (^) Lactic acidosis can result from: ◯ (^) Heavy exercise ◯ (^) Seizure activity ◯ (^) Hypoxia ● (^) Excessive intake of acids ◯ (^) Ethyl alcohol ◯ (^) Methyl alcohol ◯ (^) Acetylsalicylic acid (aspirin) ● (^) Inadequate elimination of hydrogen ions ◯ (^) Kidney failure ◯ (^) Severe lung problems ● (^) Inadequate production of bicarbonate ◯ (^) Kidney failure ◯ (^) Pancreatitis ● (^) Impaired liver or pancreatic function: Liver failure ● (^) Excess elimination of bicarbonate: Diarrhea
RESULTS IN
● (^) Decreased HCO 3 ‑ ● (^) Increased H+^ concentration
MANIFESTATIONS
● (^) Dysrhythmias ● (^) Vital signs: Bradycardia, weak peripheral pulses, hypotension, tachypnea ● (^) Neurological: Headache, drowsiness, confusion ● (^) Respiratory: Rapid, deep respirations (Kussmaul respirations) ● (^) Skin: Warm, dry, pink
NURSING CARE: Varies with causes. If DKA, administer
insulin. If related to GI losses, administer antidiarrheals and provide rehydration. If serum bicarbonate is low, administer sodium bicarbonate 1 mEq/kg.
284 CHAPTER 45 Acid‑BAse imBAlAnces CONTENT MASTERY SERIES
Application Exercises
1. A nurse is caring for a client
admitted with confusion and lethargy. The client was found at home unresponsive with an empty bottle of aspirin lying next to her bed. Vital signs reveal blood pressure 104/72 mm Hg, heart rate 116/min with regular rhythm, and respiratory rate 42/min and deep. Which of the following arterial blood gas findings should the nurse expect? A. pH 7. PaO 2 96 mm Hg PacO 2 38 mm Hg HcO 3 −^ 28 meq/l B. pH 7. PaO 2 100 mm Hg PacO 2 28 mm Hg HcO 3 −^ 23 meq/l c. pH 6. PaO 2 100 mm Hg PacO 2 30 mm Hg HcO 3 −^ 18 meq/l d. pH 7. PaO 2 96 mm Hg PacO 2 38 mm Hg HcO 3 −^ 29 meq/l
2. A nurse is caring for a client who
was in a motor‑vehicle accident. The client reports chest pain and difficulty breathing. A chest x‑ray reveals the client has a pneumothorax. Which of the following arterial blood gas findings should the nurse expect? A. pH 7. PaO 2 86 mm Hg PacO 2 52 mm Hg HcO 3 −^ 24 meq/l B. pH 7. PaO 2 100 mm Hg PacO 2 38 mm Hg HcO 3 −^ 23 meq/l c. pH 6. PaO 2 100 mm Hg PacO 2 30 mm Hg HcO 3 −^ 18 meq/l d. pH 7. PaO 2 96 mm Hg PacO 2 38 mm Hg HcO 3 −^ 29 meq/l
3. A nurse is obtaining arterial blood
gases for a client who has vomited for 24 hr. The nurse should expect which of the following acid‑base imbalances to result from vomiting for 24 hr? A. Respiratory acidosis B. Respiratory alkalosis c. metabolic acidosis d. metabolic alkalosis
4. A charge nurse is teaching a
group of nurses about conditions related to metabolic acidosis. Which of the following statements by a unit nurse indicates the teaching has been effective? A. “metabolic acidosis can occur due to diabetic ketoacidosis.” B. “metabolic acidosis can occur in a client who has myasthenia gravis.” c. “metabolic acidosis can occur in a client who has asthma.” d. “metabolic acidosis can occur due to cancer.”
5. A nurse is assessing a client who has
pancreatitis. The client’s arterial blood gases reveal metabolic acidosis. Which of the following are expected findings? (select all that apply.) A. Tachycardia B. Hypertension c. Bounding pulses d. Hyperreflexia e. dysrhythmia F. Tachypnea
PRACTICE Active Learning Scenario
A nurse is caring for a client who has liver cancer. The client’s arterial blood gases reveal metabolic acidosis. Use the ATi Active learning Template: system disorder to complete this item. RISK FACTORS: include three conditions related to metabolic acidosis. NURSING CARE: include two nursing actions. COMPLICATIONS: identify one.
RN ADULT MEDICAL SURGICAL NURSING CHAPTER 45 Acid‑BAse imBAlAnces 285
Application Exercises Key
- A. These arterial blood gases indicate metabolic alkalosis. B. These arterial blood gases indicate respiratory alkalosis. c. CORRECT: An aspirin overdose would result in arterial blood gas findings of metabolic acidosis. d. These arterial blood gases indicate metabolic alkalosis. NCLEX®^ Connection: Reduction of Risk Potential, Laboratory Values
- A. CORRECT: A pneumothorax can cause alveolar hyperventilation and increased carbon dioxide levels, resulting in a state of respiratory acidosis. B. These ABGs are within the expected reference range and reflect homeostasis. c. metabolic acidosis is not indicated for this client. d. metabolic alkalosis is not indicated for this client. NCLEX®^ Connection: Reduction of Risk Potential, Laboratory Values
- A. Respiratory acidosis is not indicated for this client. B. Respiratory alkalosis is not indicated for this client. c. metabolic acidosis is not indicated for this client. d. CORRECT: excessive vomiting causes a loss of gastric acids and an accumulation of bicarbonate in the blood, resulting in metabolic alkalosis. NCLEX®^ Connection: Physiological Adaptation, Fluid and Electrolyte Imbalances
- A. CORRECT: metabolic acidosis results from an excess production of hydrogen ions, which occurs in diabetic ketoacidosis. B. Respiratory acidosis can occur in a client who has myasthenia gravis. c. Respiratory acidosis can occur in a client who has asthma. d. Respiratory acidosis can occur due to cancer. NCLEX®^ Connection: Physiological Adaptation, Fluid and Electrolyte Imbalances
- A. Tachycardia is an expected finding for a client who has respiratory acidosis or metabolic alkalosis. B. Hypertension is an expected finding of respiratory acidosis. c. Bounding pulses is an expected finding for respiratory acidosis due to hypertension. d. Hyperreflexia is an expected finding for a client who has metabolic alkalosis. e. CORRECT: dysrhythmia is an expected finding in a client who has pancreatitis and metabolic acidosis. F. CORRECT: Tachypnea is an expected finding in a client who has pancreatitis and metabolic acidosis. NCLEX®^ Connection: Physiological Adaptation, Illness Management
PRACTICE Answer
Using ATI Active Learning Template: System Disorder RISK FACTORS metabolic acidosis results from: ● (^) excess production of hydrogen ions ● (^) diabetic ketoacidosis (dKA) ● (^) starvation lactic acidosis can result from: ● (^) Heavy exercise ● (^) seizure activity ● (^) Hypoxia ● (^) excessive intake of acids such as the following: ◯ (^) ethyl alcohol ◯ (^) methyl alcohol ◯ (^) Acetylsalicylic acid (aspirin) ● (^) inadequate elimination of hydrogen ions ◯ (^) Kidney failure ◯ (^) severe lung problems ● (^) inadequate production of bicarbonate ◯ (^) Kidney failure ◯ (^) Pancreatitis ◯ (^) impaired liver or pancreatic function ◯ (^) liver failure ● (^) excess elimination of bicarbonate (diarrhea) metabolic acidosis results in: ● (^) decreased HcO 3 ‑ ● (^) increased H+ (^) concentration NURSING CARE: Varies with causes. if dKA, administer insulin. if related to Gi losses, administer antidiarrheals and provide rehydration. if serum bicarbonate is low, administer sodium bicarbonate 1 meq/kg. COMPLICATIONS: convulsions, coma, and respiratory arrest nursing Actions ● (^) implement seizure precautions, and perform management interventions if necessary. ● (^) Provide life‑support interventions if necessary. NCLEX®^ Connection: Physiological Adaptation, Fluid and Electrolyte Imbalances
