Respiratory Acidosis

Chronic respiratory acidosis is associated with

chronic respiratory or neuromuscular conditions such as COPD, asthma, cystic fibrosis, and multiple sclerosis. These conditions affect alveolar ventilation because of airway obstruction, structural changes in the lung, and limited chest wall expansion.

Pulmonary function studies

may be done to determine whether chronic lung disease is the cause of the respiratory acidosis. However, these studies are not done during the acute period.

Respiratory Support

ocuses on improving alveolar ventilation and gas exchange. Patients with severe respiratory acidosis and hypoxemia may require intubation and mechanical ventilation. The PaCO2level is lowered slowly to prevent complications such as cardiac dysrhythmias and decreased cerebral perfusion. In patients with chronic respiratory acidosis, oxygen is administered cautiously to prevent carbon dioxide narcosis. Pulmonary hygiene measures may be instituted

Risk Factors

Acute or chronic lung disease (e.g., pneumonia, COPD) or trauma is the primary risk factor for respiratory acidosis. Other conditions that depress or interfere with ventilation, such as excess narcotic analgesics, airway obstruction, and neuromuscular disease, also are risk factors for respiratory acidosis.

Patients with chronic respiratory acidosis have

COPD with chronic bronchitis and emphysema.

Hypoxemia

Decreased oxygen levels in the blood that result when PaO2 falls below 80 mmHg.

Patients with chronic respiratory acidosis are at risk for

Developing carbon dioxide narcosis (with manifestations of acute respiratory acidosis) if the respiratory center is suppressed by the administration of excess supplemental oxygen.

Physical examination

Examine mental status and LOC; vital signs, skin color and temperature; and rate and depth of respirations, pulmonary excursion, and lung sounds.

Planning

Involves both restoration of acid-base balance and appropriate treatment for any underlying disease or cause.

Chronic Respiratory Acidosis

The PaCO2 increases over time and remains elevated. The kidneys retain bicarbonate, increasing bicarbonate levels, and the pH often remains close to the normal range because of adequate metabolic compensation.

Serum electrolytes

may show hypochloremia (chloride level below normal) in chronic respiratory acidosis.

Pharmacologic Therapy

A bronchodilator may be administered to open the airways. Antibiotics are prescribed to treat respiratory infections. If excess narcotics or anesthetic caused the acute respiratory acidosis, narcotic antagonists such as naloxone may be given to reverse the effects.

Hypercapnia

A condition marked by a PaCO2 level above 45 mmHg. Also known as hypercarbia.

Respiratory acidosis

A condition that is caused by an excess of dissolved carbon dioxide, or carbonic acid. It is characterized by a pH of less than 7.35 and a PaCO2 greater than 45 mmHg. It may be caused by hypoventilation.

Collaboration

A respiratory therapist may provide breathing treatments and related therapies as ordered. Consultation with the pharmacist and the patient's primary care provider prevents administration of medications that may be contraindicated. Patients who are using accessory muscles to breathe may require increased caloric intake and the participation of a dietitian.

Respiratory Acidosis in Older Adults

Many illnesses common to older adults may result in acid-base imbalance if not properly treated. COPD, chest wall abnormalities, pneumonia, and respiratory muscle weakness are some of the common causes of respiratory acidosis in older adults. CO2 retention from hypoventilation occurs, and the compensatory response is HCO3 retention by the kidneys. Older adults are more prone to have COPD. Outcome depends on the nature of the illness and early diagnosis/treatment.

Nursing Process

Nursing care of patients with respiratory acidosis is focused on improving breathing patterns and maintaining a patent airway. Because of the link between smoking and chronic pulmonary diseases, nursing care may include teaching patients how to make healthier lifestyle choices.

Hypercapnia & Acute Respiratory Acidosis

(increased carbon dioxide levels) affects neurologic function and the cardiovascular system. Carbon dioxide rapidly crosses the blood-brain barrier. Cerebral blood vessels dilate, and if the condition continues, intracranial pressure increases and papilledema (swelling and inflammation of the optic nerve where it enters the retina) develops. Peripheral vasodilation also occurs, and the pulse rate increases to maintain cardiac output. The primary problem is alveolar hypoventilation with increased PaCO2.

Diagnostic Tests

ABGs Serum Electrolytes Pulmonary Function Studies Find Underlying Cause: Chest X Ray Sputum Studies (cytology and culture) If drug overdose is suspected, serum levels of the drug may be obtained.

Respiratory acidosis can be caused by

Acute pulmonary edema, central nervous system depression, chest wall disorders, trauma, oversedation, asthma, obstructive sleep apnea, obesity, and pulmonary infections.

Observation and patient interview

Ask the patient about current manifestations, including headache, irritability, lethargy, difficulty thinking, blurred vision, and other symptoms; duration of symptoms and any precipitating factors such as drug use or respiratory infection; chronic diseases such as cystic fibrosis or COPD; and current medications.

Pathophysiology and Etiology

Both acute and chronic respiratory acidosis result from carbon dioxide retention caused by alveolar hypoventilation. Hypoxemia (decreased oxygen) frequently accompanies respiratory acidosis.

Manifestations of Chronic Respiratory Acidosis

Confusion, tremors, and convulsions; coma can occur if blood levels of PaCO2 reach 70 mmHg or higher. Patients with chronic respiratory acidosis can tolerate PaCO2 levels that are much higher than normal.

Pulmonary Hygiene

Deep breathing and coughing exercises, breathing treatments, and percussion and drainage. Adequate hydration is important to promote removal of respiratory secretions.

Etiology

Diseases of the airways, such as asthma, chronic obstructive lung disease Disease of the chest Drugs that suppress breathing, such as opioids, or alcohol Obstructive sleep apnea

Implementation

Frequently assess respiratory status, including rate, depth, effort, and oxygen saturation levels. Decreasing respiratory rate and effort along with decreasing oxygen saturation levels may signal worsening respiratory failure and respiratory acidosis.

Plan for Discharge

Planning and teaching for home care focus on the problem that caused the respiratory acidosis. • Teach the patient and family about preventive measures and equipment that may be used in the home. The patient who developed acute respiratory acidosis as a result of acute pneumonia or chest trauma may require only teaching to prevent future problems. • If acute respiratory acidosis occurred secondarily to a narcotic overdose, determine whether the drug was prescribed for pain or whether it was an illicit street drug. Provide teaching to the patient who requires continuous narcotic medication. Refer the patient using illicit drugs to a substance abuse counselor, treatment center, or Narcotics Anonymous, as appropriate; refer the family to support groups as well. • For patients with chronic lung disease and their families, discuss ways to avoid future episodes of acute respiratory failure. Encourage the patient to receive immunization against pneumococcal pneumonia and influenza. Discuss with the patient and family ways to avoid acute respiratory infections, such as good hand hygiene, crowd avoidance, and respiratory cough etiquette. • Provide instructions regarding measures to take when respiratory status is further compromised. The patient and family should be alerted that symptoms such as headache accompanied by blurred vision or weakness, irritability and confusion, or sleep disturbances and memory impairments warrant immediate medical attention. Shortness of breath or activity intolerance are often the earliest symptoms of worsening respiratory status. Wheezing, grunting, use of accessory muscles, and cyanosis are often late signs.

Diagnosis

Restoring effective alveolar ventilation and gas exchange is the priority of interprofessional and nursing care for patients with respiratory acidosis. • Airway Clearance, Ineffective • Anxiety • Breathing Pattern, Ineffective • Cardiac Output, Decreased Gas Exchange, Impaired.

Acute Respiratory Acidosis

Results from a sudden failure of ventilation (the exchange of oxygen and carbon dioxide). Chest trauma, aspiration of a foreign body, acute pneumonia, and overdoses of narcotic or sedative medications can lead to this condition. PaCO2 rises rapidly and the pH falls markedly. A pH of 7 or lower can occur within minutes, resulting in death if not corrected The serum bicarbonate level is unchanged initially because the compensatory response of the kidneys continues over hours to days.

Carbon Dioxide and Chronic Respiratory Acidosis

The acute effects of hypercapnia may not develop when carbon dioxide levels rise gradually, allowing compensatory changes to occur. When carbon dioxide levels are chronically elevated, the respiratory center becomes less sensitive to the gas as a stimulant of the respiratory drive. The PaO2 provides the primary stimulus for respirations.

Evaluation

The evaluation of nursing care is based on the patient's progress in meeting goals, and the nurse revises the plan of care as indicated by outcomes. Expected outcomes of nursing care for a patient with respiratory acidosis include the following: • Patient maintains patent airway. • Patient maintains appropriate breathing patterns to meet oxygen demands. • Patient remains conscious and does not display anxiety indicating potential hypoxia. • ABG reflects pH and PaCO2 within an acceptable range for the patient.

Ventilation

The exchange of oxygen and carbon dioxide.

ABGs

show a pH of less than 7.35 and a PaCO2 of more than 45 mmHg. In acute respiratory acidosis, the bicarbonate level is initially within the normal range but increases to greater than 28 mEq/L if the condition persists. In chronic respiratory acidosis, both the PaCO2 and the HCO3 may be significantly elevated.

Planning: Expected Outcomes

• Adequate fluid intake • Oxygenation saturation greater than 90% • Normal PaCO2 levels • pH balance.

Reduce Risk for Injury

• Assess LOC, mental status, orientation frequently. • Place call alarm controls within reach. • Manage rest and activity patterns to improve gas exchange and reduce oxygen demands. • Administer supplemental oxygen as needed to prevent cellular hypoxia and tissue damage.

Clinical Therapies

• Assist with identification/treatment of underlying cause. • Observe for altered respiratory excursion, rate, and depth. Auscultate breath sounds. • Assess LOC and progressive changes. • Place in semi-Fowler position or Fowler position as tolerated. • Encourage the patient with chronic respiratory acidosis to use pursed-lip breathing. • Administer oxygen as indicated by mask, cannula, or mechanical ventilation. Increase or decrease respiratory rate on ventilator. Modify respiratory settings as needed. • Administer medications as indicated; for example, naloxone hydrochloride (Narcan). • Use continuous positive airway pressure (CPAP).

Promote Effective Airway Clearance

• Frequently auscultate lung sounds (whether the patient is on or off a mechanical ventilator). Increasing adventitious sounds or decreasing breath sounds (faint or absent) may indicate worsening airway clearance due to obstruction or fatigue. • Encourage the patient with chronic respiratory acidosis to use pursed-lip breathing. Pursed-lip breathing helps maintain open airways throughout exhalation, promoting carbon dioxide elimination. See the Patient Teaching feature on Effective Coughing in the module on Oxygenation for detailed instructions on purse-lipped breathing. • Frequently reposition and encourage ambulation as tolerated. Repositioning, sitting at the bedside, and ambulation promote airway clearance and lung expansion. • Encourage fluid intake. Fluids help liquefy secretions and hydrate respiratory mucous membranes, promoting airway clearance. • Administer medications such as inhaled bronchodilators as ordered. Inhaled bronchodilators help relieve bronchial spasm, dilating airways. • Provide percussion, vibration, and postural drainage as ordered. Pulmonary hygiene measures such as these help loosen respiratory secretions.

Clinical Manifestations: Acute Respiratory Acidosis

• Headache • Warm, flushed skin • Elevated pulse • Blurred vision • Irritability or altered mental status • Decreasing LOC • Cardiac dysrhythmias • Cardiac arrest

Promote Gas Exchange

• Promptly evaluate and report ABG results to the physician and respiratory therapist. Rapid changes in carbon dioxide or oxygen levels may necessitate modification of the treatment plan to prevent complications of overcorrection of respiratory acidosis. • Place in semi-Fowler to Fowler position as tolerated. Elevating the head of the bed promotes lung expansion and gas exchange. • Administer oxygen as ordered. Carefully monitor response. Reduce the oxygen flow rate or percentage and immediately report increasing somnolence. Supplemental oxygen can suppress the respiratory drive in patients with chronic respiratory acidosis.

Reduce Anxiety Levels

• Remain with the patient and monitor for changes in condition. • Explain procedures and treatments using short, simple sentences. Providing clearly understood information reduces fear of the unknown. • Reduce environmental stimuli, and use a calm, reassuring manner. These measures help reduce anxiety. • Allow supportive family members to remain with the patient as much as possible to provide further reassurance.

Clinical Manifestations: Chronic Respiratory Acidosis

• Weakness • Dull headache • Sleep disturbances with daytime sleepiness • Impaired memory • Personality changes