Metabolic acidosis is characterized by an imbalance in the body’s acid-base balance and occurs when there is a buildup of acid in the blood. Causes include:
- Reduced ability of the kidneys to excrete excess acids
- Increased acid production
- Too much bicarbonate is lost
The body attempts to compensate for this imbalance through the respiratory system by hyperventilation to blow off excess CO2 to raise the blood pH and readjust the bicarbonate to CO2 ratio.
In this article:
- Nursing Process
- Nursing Assessment
- Nursing Interventions
- Nursing Care Plans
- Ineffective Tissue Perfusion
- Risk for Decreased Cardiac Output
- Risk for Electrolyte Imbalance
- Risk for Injury
Nursing Process
The ultimate goal in the management of metabolic acidosis is to correct and maintain a healthy balance of the body’s acid-base levels. Treatment of this condition includes correcting the underlying cause and raising the blood pH through oral or intravenous sodium bicarbonate. Monitoring vital signs, laboratory results, and level of consciousness is also a priority to determine the effectiveness of the treatment regimen and to prevent complications.
Nursing Assessment
The first step of nursing care is the nursing assessment, during which the nurse will gather physical, psychosocial, emotional, and diagnostic data. In this section, we will cover subjective and objective data related to metabolic acidosis.
Review of Health History
1. Record the patient’s general symptoms.
Symptoms of metabolic acidosis are associated with the underlying cause, including:
- General: fatigue, generalized weakness
- CNS: acute confusion, headache, drowsiness
- Respiratory: hyperventilation
- Cardiovascular: chest pain, palpitations, hypotension
- GI: nausea, vomiting, diarrhea
- Musculoskeletal: decreased muscle tone and reflexes
2. Identify the causative factor.
Causes of metabolic acidosis include the following:
- Diabetic ketoacidosis
- Starvation
- Lactic acidosis
- Diarrhea
- Dehydration
- Renal failure
- Renal tubular acidosis
- Liver failure
- Gastrointestinal fistulas
- Aspirin overdose
- Shock
3. Review the patient’s medication record.
Patients may experience metabolic acidosis as a result of toxicity from:
- Metformin
- Nonsteroidal anti-inflammatory medications (NSAIDs)
- Salicylates (aspirin)
- Valproate
- Isoniazid
- Propofol
4. Ask about the patient’s exposure to certain toxins.
The following toxins can induce metabolic acidosis:
- Methanol (a chemical used in fuels and solvents)
- Ethylene glycol (a chemical found in antifreeze)
- Isopropyl alcohol
- Butoxyethanol
- Toluene
Physical Assessment
1. Assess the patient’s respirations.
Note Kussmaul’s respirations which are rapid, deep breaths at a regular rhythm. This breathing pattern is common in patients with DKA.
2. Assess mental status changes.
Severe metabolic acidosis can cause confusion and drowsiness and can lead to shock and coma. Monitor for any changes in mentation.
3. Monitor vital signs.
Watch out for signs of shock that may include hypotension and tachycardia. Hyperventilation is the respiratory system’s attempt to rid the body of excess acid.
4. Note for symptoms associated with specific conditions.
Symptoms of metabolic acidosis depend on the underlying etiology. Symptoms may include:
- Due to kidney or liver failure:
- Dry skin (xerosis)
- Scratch marks on the skin
- Pale skin (pallor)
- Sleepiness
- Involuntary motor control (asterixis)
- Due to DKA:
- Poor skin turgor
- Dry mucous membranes
- Fruity breath odor
- Rapid breathing
Diagnostic Procedures
1. Take blood samples for ABG testing.
Interpret the ABG. To confirm metabolic acidosis, arterial blood gas results will show:
- pH <7.35
- PaCO2 35-45 mmHg (may be normal or low)
- HCO3 <22 mEq/L
2. Obtain blood for testing.
Elevated white blood cell (WBC) counts indicate septicemia, which can cause lactic acidosis.
3. Examine the urine.
Acidic urine often has a pH of less than 5.0. Needle-shaped calcium oxalate crystals are detected in the urine of patients with ethylene glycol toxicity.
4. Check the ketone level.
Increased ketone levels indicate diabetic ketoacidosis or starvation.
5. Obtain serum lactate level.
The normal range for plasma lactate is 0.5 to 1.5 mEq/L. Plasma lactate levels exceeding 4-5 mEq/L are present in patients with acidosis.
6. Determine the salicylate and iron levels.
Plasma salicylate levels greater than 40–50 mg/dL diagnose aspirin poisoning. A toxic iron level exceeds 300 mg/dL and is associated with lactic acidosis.
7. Assess electrolytes.
Severe dehydration from vomiting and diarrhea can cause acidosis. Monitor potassium, sodium, magnesium, phosphorus, bicarbonate, and chloride levels for imbalances.
8. Prepare the patient for imaging scans.
Patients may exhibit renal stones through the following tests:
- Abdominal radiographs (kidneys, ureters, or bladder)
- Computed tomography (CT) scans
- Renal ultrasound imaging
9. Attach the patient to ECG.
Electrolyte imbalances (hyperkalemia) impact the heart, causing dysrhythmias.
Nursing Interventions
Nursing interventions and care are essential for the patients recovery. In the following section, you will learn more about possible nursing interventions for a patient with metabolic acidosis.
1. Address the underlying cause.
Address the primary cause of metabolic acidosis. Sepsis requires aggressive IV antibiotics, while diabetic ketoacidosis requires fluid resuscitation, correction of electrolyte imbalances, and insulin.
2. Administer medications as prescribed.
Prepare to administer these medications for a patient with metabolic acidosis.
- Alkalinizing agents like sodium bicarbonate treat acute metabolic acidosis to increase plasma pH and keep it above 7.20.
- Carbonic anhydrase inhibitors cause alkaline diuresis.
- Detoxification agents treat methanol or ethylene glycol poisoning.
3. Reverse metabolic acidosis.
The most common agent for metabolic acidosis is IV sodium bicarbonate (NaHCO3). Blood pH, serum HCO3 level, and PaCO2 determine the sodium bicarbonate dose.
4. Manage metabolic acidosis in CKD.
Increase the bicarbonate concentration of the dialysate solution or administer oral sodium bicarbonate during dialysis for patients with CKD.
5. Address salicylate toxicity.
Acetazolamide treatment or intravenous sodium bicarbonate injection can start alkaline diuresis. Use multiple doses of activated charcoal every 2–4 hours to boost salicylate excretion.
6. Prepare for dialysis.
Consider hemodialysis for patients with severe metabolic acidosis caused by:
- Large overdoses or toxin ingestion
- Acute renal injury
- Severe central nervous system (CNS) depression
7. Start antibiotics.
Initiate antibiotics for a septic shock that can cause metabolic acidosis. The primary treatment for septic shock is empiric antibiotic therapy.
8. Supplement with potassium citrate.
Patients with renal tubular acidosis type 1 will require a daily alkalinizing agent because the kidneys do not remove acids through the urine as normal. Potassium citrate is usually recommended.
9. Detoxify the patient immediately.
These are the toxins that can cause metabolic acidosis and their antidotes:
- Ethylene glycol (EG), Diethylene glycol (DEG), and methanol: Fomepizole (prevents alcohol dehydrogenase)
- Acetaminophen: N-acetylcysteine (NAC) within 8 hours of ingestion
10. Refer to a dietitian.
Refer the patient with CKD to a renal dietician or nutritionist specializing in kidney diseases. The patient can be instructed on reducing acid-producing foods and eating more base-producing foods.
11. Educate on acid-producing/base-producing food.
The body produces acids in response to the following foods and beverages:
- Fish/seafood
- Processed meats
- Eggs
- Cheese
- Grains
- Alcohol
- Carbonated beverages
These foods create a more alkaline environment:
- Fruit
- Nonstarchy vegetables
- Almond milk
- Coconut oil
- Soy
Nursing Care Plans
Once the nurse identifies nursing diagnoses for metabolic acidosis, nursing care plans help prioritize assessments and interventions for both short and long-term goals of care. In the following section, you will find nursing care plan examples for metabolic acidosis.
Acute Confusion
Metabolic acidosis leads to acid buildup in the body and often causes changes in mental status.
Nursing Diagnosis: Acute Confusion
Related to:
- Disease process
- Electrolyte imbalance
- Impaired metabolism
As evidenced by:
- Alterations in consciousness
- Difficulty initiating goal-directed behavior
- Difficulty initiating purposeful behavior
- Inappropriate responses
- Disorientation
- Lethargy
- Psychomotor agitation
Expected outcomes:
- Patient will remain oriented to person, place, time, and situation.
- Patient will demonstrate alertness and appropriate decision-making.
Assessment:
1. Assess the causative factors for the patient’s confusion.
Understanding the underlying cause of the patient’s alteration in mental status can help formulate an appropriate plan of care. Assess glucose levels and lab work, and perform a medication review.
2. Perform a neurological assessment.
A thorough neurological assessment can help differentiate systemic conditions from neurologic or psychiatric disorders. It can help guide appropriate interventions, diagnostics tests, and referrals to other providers.
Interventions:
1. Orient the patient as needed.
Since metabolic acidosis causes confusion, frequent reorientation allows the patient to comprehend the situation and remain aware of the current setting.
2. Closely monitor laboratory results.
When initiating treatment for metabolic acidosis, it’s vital that the nurse reviews the results of ongoing lab testing, such as ABGs, electrolyte levels, ammonia levels, and kidney function.
3. Explain procedures and interventions.
Patients with metabolic acidosis are often confused and will require explanations about nursing interventions and procedures. An understanding of procedures and treatment promotes adherence and reduces anxiety or agitation.
4. Plan care that allows adequate sleep and rest.
Sleep deprivation can aggravate confusion in patients with metabolic acidosis.
Ineffective Tissue Perfusion
Acidic blood leads to inadequate oxygenation that can cause shock, coma, and death.
Nursing Diagnosis: Ineffective Tissue Perfusion
Related to:
- Increased hydrogen concentration
- Hemodynamic instability (shock)
- Exposure to toxic chemicals
- Renal failure
As evidenced by:
- Hypotension (SBP <90 mmHg)
- Mean Arterial Pressure (<65 mmHg)
- Tachycardia
- Tachypnea
- Weak peripheral pulses
- Cool, clammy skin
- Prolonged capillary refill
- Altered mental status
Expected outcomes:
- Patient will maintain optimal tissue perfusion as evidenced by the following:
- SBP >90 mmHg
- MAP >65 mmHg
- Pulse rate: 60-100 beats/min
- Respiratory Rate: 12-20 breaths/min
- Strong, palpable pulses
- Warm and dry extremities
- Capillary Refill Time of <2 secs
- Patient will not display alterations in alertness or mentation.
Assessment:
1. Monitor trends in blood pressure.
Metabolic acidosis can worsen to shock and coma. Patients who are septic may display lactic acidosis. Blood pressure is a sensitive indicator of tissue perfusion. Note progressive hypotension and widening pulse pressure.
2. Monitor heart rate and rhythm.
The sympathetic nervous system triggers tachycardia as a compensatory response to hypovolemia and hypotension. Metabolic acidosis can lead to hyperkalemia which causes cardiac arrhythmias, reducing perfusion.
3. Monitor neurological status.
Drowsiness and confusion can occur from an acidic blood pH and is concerning for CNS depression, coma, and death. Perform neurological checks frequently.
Interventions:
1. Administer IV sodium bicarbonate.
Sodium bicarb is the treatment of choice to raise the HCO3 level and correct acidosis.
2. Treat hypovolemia and shock.
Antibiotics, crystalloids, colloids, and blood products may be necessary depending on the cause of acidosis and hypovolemia.
3. Administer oxygen therapy if indicated.
Supplemental oxygen improves tissue oxygenation and perfusion.
4. Administer vasopressors as ordered.
In severe cases of metabolic acidosis and impaired tissue perfusion (shock), vasopressors (i.e., vasopressin, norepinephrine, epinephrine, dopamine) may be used to improve blood pressure and perfusion to vital organs.
Risk for Decreased Cardiac Output
The patient with metabolic acidosis is at risk for dysrhythmias related to hyperkalemia.
Nursing Diagnosis: Risk for Decreased Cardiac Output
Related to:
- Increased hydrogen concentration
- Alteration in cardiac rhythm
- Decreased contractility
- Electrolyte imbalances
As evidenced by:
A risk diagnosis is not evidenced by signs and symptoms as the problem has not yet occurred. Nursing interventions are aimed at prevention.
Expected outcomes:
- Patient will manifest adequate cardiac output as evidenced by the following:
- Blood pressure: SBP: >90 – <140 / DBP: >60 – <90 mmHg
- Heart rate: 60 to 100 beats/min
- Urine output 0.5 to 1.5 cc/kg/hour
- Strong peripheral pulses
- ECG results will exhibit a normal sinus rhythm.
Assessment:
1. Monitor heart rate and rhythm.
Alterations in electrolytes, specifically potassium, increase the risk of dysrhythmias. Hyperkalemia is a potential complication of acidosis.
2. Monitor for causative factors of dysrhythmia and metabolic acidosis.
The most effective approach to dysrhythmias is correcting or eliminating precipitating factors. Causes of metabolic acidosis may include diabetic ketoacidosis (DKA), dehydration, renal failure, carbon monoxide poisoning, medication (i.e., salicylates, metformin) adverse effects, and excessive alcohol intake.
Interventions:
1. Review medications.
Medications that can cause hyperkalemia, such as angiotensin II receptor blockers, beta-blockers, calcium channel blockers, and potassium-sparing diuretics, should be discontinued
2. Apply EKG.
The patient with metabolic acidosis should receive continuous ECG monitoring.
3. Take care in treating renal tubular acidosis type 4.
This type of RTA is most common and causes metabolic acidosis because the kidneys cannot excrete potassium effectively. Patients with this condition need a low-potassium diet and may benefit from loop diuretics.
4. Consider dialysis.
Patients with severe CNS depression or acute renal injury may benefit from hemodialysis to correct acidosis, remove toxins, and rid the body of excess potassium.
Risk for Electrolyte Imbalance
Metabolic acidosis is a serious disorder associated with an imbalance in the acid-base balance in the body. The body attempts to increase bicarbonate by exchanging hydrogen for potassium in the cells, moving potassium into the blood, leading to hyperkalemia.
Nursing Diagnosis: Risk for Electrolyte Imbalance
Related to:
- Disease process
- Compromised regulatory mechanism
- Endocrine regulatory dysfunction
- Fluid imbalance
- Effects of metabolic acidosis
- Renal dysfunction
As evidenced by:
A risk diagnosis is not evidenced by signs and symptoms as the problem has not yet occurred. Nursing interventions are aimed at prevention.
Expected outcomes:
- Patient will maintain normal levels of electrolytes.
- Patient will exhibit normal vital signs with normal sinus rhythm on EKG.
Assessment:
1. Assess cardiac rate and rhythm.
Hyperkalemia caused by metabolic acidosis may manifest as cardiac irregularities. Monitor the EKG for tall, peaked T waves, which signify severe hyperkalemia.
2. Assess and monitor electrolyte levels.
Tests to assess electrolyte levels can help identify alterations, allowing prompt treatment.
Interventions:
1. Evaluate changes in breathing.
Patients with metabolic acidosis often exhibit hyperventilation as a compensatory response to remove excess acid.
2. Administer parenteral fluids as indicated.
The administration of fluids impacts plasma electrolytes and promotes hemodynamic improvement.
3. Evaluate urinary status.
The kidneys compensate for metabolic acidosis by excreting excess hydrogen ions. When there is reduced renal perfusion, there is decreased renal output, as the kidneys will retain fluids and sodium. Closely monitor intake and output.
4. Administer medications as indicated.
Oral or intravenous sodium bicarbonate is often prescribed to raise blood pH levels.
Risk for Injury
Patients with metabolic acidosis often feel weak, tired, and confused, causing an increased risk for injuries. Acidosis can also result in seizures.
Nursing Diagnosis: Risk for Injury
Related to:
- Electrolyte imbalances
- Hypoxia
- Disorientation
- Muscle weakness
- Fatigue
- Toxin accumulation
As evidenced by:
A risk diagnosis is not evidenced by signs and symptoms as the problem has not yet occurred. Nursing interventions are aimed at prevention.
Expected outcomes:
- Patient will remain free of injuries.
- Patient will not experience seizure activity.
Assessment:
1. Assess the patient’s risk factors for injuries.
Metabolic acidosis causes symptoms like weakness, confusion, fatigue, and bone loss which can increase the patient’s risk for injuries.
2. Assess the patient’s age, developmental stage, cognitive awareness, and decision-making ability.
These factors can determine the patient’s ability to keep themselves free from injuries. Proper identification can help formulate an appropriate plan of care and patient education.
Interventions:
1. Provide a safe environment.
Patients with metabolic acidosis can become confused and weak and experience injuries from common hazards. Prevent injuries by keeping the bed low with the alarm on and the call bell within reach.
2. Assist the patient in ambulation and encourage the use of assistive aids.
Assistive aids like wheelchairs and walkers can help the patient ambulate. Assist the patient in ambulation and self-care to prevent falls and injuries.
3. Involve the patient and family members in patient care.
A better understanding of the patient’s condition can ensure adherence and encourage the involvement of family members in patient care. Round-the-clock patient monitoring decreases the patient’s risk for injuries.
4. Implement seizure precautions.
Seizures may occur as a result of electrolyte imbalances or toxin accumulation. Implement seizure precautions by padding bed rails, placing mats on the floor, and having emergency equipment at the bedside.
References
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