Acid-base disturbance characterized by reduced alveolar ventilation resulting in hypercapnia
Verified by arterial blood gas analysis (partial pressure of arterial carbon dioxide [PaCO2] above 45 mm Hg and pH less than 7.35)
Diagnosed when serum pH is reduced and serum bicarbonate concentration is abnormally low
Prognosis varies depending on the severity of the underlying cause and the patient's general condition
Can be acute or chronic

Pathophysiology

Inadequate ventilation causes carbon dioxide to be retained (hypercapnia). Carbon dioxide and water combine to make carbonic acid, leading to a decrease in the bicarbonate level and then in the hydrogen ion (pH) concentration.
With chronic respiratory acidosis, PaCO2 is elevated but pH is normal or near-normal because of compensation by the kidneys.
Cellular compensatory buffering (increase in bicarbonate) may occur over minutes to hours, with kidney compensation occurring over 3 to 5 days.

Causes

Elevated carbon dioxide levels resulting from respiratory depression or failure
Compensatory mechanism for severe metabolic acidosis

Risk Factors

Airway obstruction
Asthma
Central nervous system (CNS) disorder or depression
Chest wall disorders, such as flail chest or severe kyphoscoliosis
Chronic bronchitis
Chronic metabolic alkalosis
Chronic obstructive pulmonary disease
CNS-depressant drug use
Extensive pneumonia
Large pneumothorax
Neuromuscular disease
Obstructive sleep apnea
Parenchymal lung disease
Pulmonary edema
Severe acute respiratory distress syndrome
Obesity hypoventilation syndrome
Laryngeal or tracheal stenosis
Interstitial lung disease

Incidence

Respiratory acidosis affects males and females equally.

Complications

Metabolic alkalosis
Cor pulmonale
Carbon dioxide narcosis
Papilledema
Polycythemia
Pulmonary hypertension
Right ventricular failure
Shock
Respiratory arrest
Cardiac arrest

Assessment

History

History of underlying condition or disorder
Headache
Shortness of breath
Nausea and vomiting
Daytime sleepiness
Anxiety that progresses to confusion, somnolence, and possible delirium
Disturbed sleep
Illicit drug use

Physical Findings

May be related to underlying cause
Diaphoresis
Bounding pulses
Rapid, shallow respirations
Tachycardia and other arrhythmias
Hypotension
Papilledema
Mental status changes
Asterixis (tremor)
Seizures
Depressed deep tendon reflexes
Wheezing, barrel chest, decreased breath sounds, hyperresonance on percussion, and prolonged expiration (patients with chronic obstructive lung disease)
Clubbing (with chronic respiratory disease)
Cyanosis (if hypoxemia is present)
Somnolence (See Signs and symptoms of respiratory acidosis.)

Signs and symptoms of respiratory acidosis

Respiratory acidosis occurs when the lungs can't remove enough carbon dioxide (CO2) produced by the body. Excess CO2 lowers the pH of the blood, making it too acidic, which in turn affects a number of body systems.

Diagnostic Test Results

Laboratory

Arterial blood gas analysis shows PaCO2 above 45 mm Hg (hypercapnia); pH level 7.35 with acute occurrence may be normal with chronic respiratory acidosis secondary to compensation.
Serum bicarbonate levels may be increased (in the chronic form).
Drug screen may confirm the cause of respiratory depression.
Thyroid-stimulating hormone level (serum) and thyroxine level (serum) may identify thyroid disease as the cause.
Hemoglobin level test and hematocrit test results may be elevated with chronic hypoxemia that occurs with the chronic form of respiratory acidosis.

Imaging

Chest radiography may identify a pulmonary cause, such as obstructive pulmonary disease, pneumonia, pneumothorax, or atelectasis.
Computed tomography scanning (thorax) or magnetic resonance imaging may identify abnormalities not identified by chest radiography or a central nervous system cause, such as stroke, tumor, or trauma.

Diagnostic Procedures

Pulmonary function tests may help diagnose underlying respiratory disease; the ratio of forced expiratory volume in 1 second to forced vital capacity is decreased.
Electromyography and nerve conduction velocity tests may reveal a neuromuscular disorder as an underlying condition, such as Guillain-Barré syndrome or amyotrophic lateral sclerosis.
Transesophageal pressure measurement helps confirm diaphragmatic dysfunction and paralysis.

Treatment

General

Correction of the underlying condition causing alveolar hypoventilation
Mechanical ventilation, noninvasive positive-pressure ventilation, or noninvasive external negative-pressure ventilation
Smoking cessation
Chest tube insertion for pneumothorax
Venous thromboembolism (VTE) prophylaxis while hospitalized

Diet

Small, frequent meals
Enteral feedings if intubated
Parenteral nutrition if indicated

Activity

As tolerated

Medications

Oxygen therapy
Bronchodilators, such as albuterol sulfate, ipratropium bromide, theophylline, or tiotropium bromide
Inhaled corticosteroids, such as budesonide (inhalation, intranasal) or fluticasone propionate
medroxyPROGESTERone acetate to increase respiratory drive
acetaZOLAMIDE to increase bicarbonate excretion
Antidotes for respiratory depression caused by drug therapy, such as flumazenil for benzodiazepine overdose and naloxone hydrochloride for opioid overdose
Sodium bicarbonate (based on cause of hypercapnia)

Surgery

Surgery to treat underlying cause, if indicated
Spinal fusion to treat severe kyphoscoliosis
Bariatric surgery for obesity-associated hypoventilation

Nursing Considerations

Nursing Interventions

Give prescribed drugs; administer bronchodilators via inhalation; give IV fluids as ordered; ensure patent IV access.
Provide supplemental oxygen based on oxygen saturation levels as determined by pulse oximetry or arterial blood gas (ABG) results.
Elevate the head of the bed to maximize lung expansion; encourage the patient to take slow, deep breaths; assist with relaxation and stress management techniques.
Ensure a patent airway; suction secretions as indicated; assist with respiratory support; and assist with insertion of an endotracheal tube and mechanical ventilation as indicated.
Provide adequate fluids orally if possible.
Encourage the patient to verbalize feelings and concerns related to the condition; provide emotional support and an explanation of all treatments and care.
Provide small, frequent meals to minimize energy expenditure; allow for frequent rest periods, and cluster care to ensure adequate rest. If the patient is intubated, provide enteral feedings as ordered and assess for tolerance.
Obtain a swallowing evaluation when the patient is extubated.
Apply antiembolism stockings or sequential compression stockings to prevent VTE.
Auscultate heart and lung sounds for changes; check the patient's level of consciousness for changes.
Obtain specimens for laboratory testing, such as ABG and serum electrolyte levels, as indicated.
Obtain daily weight and check skin turgor.
Turn and reposition the patient regularly and frequently, unless contraindicated. Base the frequency of repositioning on the patient's tissue tolerance, skin condition, mobility, medical condition, and treatment goals.
Perform a skin assessment and provide skin care to prevent pressure injury formation.

Monitoring

Airway patency
Vital signs
Intake and output and fluid balance
Neurologic status
Cardiopulmonary status
Oxygen saturation level
End tidal carbon dioxide levels if monitoring available
ABG values
Serum electrolyte levels
Mechanical ventilator settings
Enteral feeding tolerance
Skin integrity
Coping status

	WARNING!
	Be aware that pulse oximetry, which is used to monitor oxygen saturation, won't reveal increasing carbon dioxide levels.

Associated Nursing Procedures

Antiembolism stocking application, knee-length
Antiembolism stocking application, thigh-length
Arterial puncture for blood gas analysis
Coughing and diaphragmatic breathing exercises
Endotracheal tube removal
Endotracheal tube repositioning
Enteral feeding tube insertion, gastric and duodenal
Enteral tube feeding, gastric
Handheld resuscitation bag and mask use
Intubation with direct visualization
IV bolus injection
IV pump use
IV secondary line drug infusion
Mechanical ventilation, positive pressure
Nasogastric or orogastric tube irrigation
Neurologic assessment
Oral care for an intubated patient
Oxygen administration
Pressure injury prevention
Relaxation and stress management techniques
Safe medication administration practices, general
Sequential compression therapy
Swallowing assessment
Weaning a patient from a ventilator

Patient Teaching

General

Include the patient's family or caregiver in your teaching, when appropriate. Provide information according to their individual communication and learning needs. Be sure to cover:

disorder, diagnostic testing, and treatment, including possible underlying causes
rationale for the use of supplemental oxygen and associated care measures, emphasizing the appropriate safety measures for oxygen use
prescribed drugs, including the drug name, dosage, route of administration, frequency of administration, expected results, and duration of therapy
how to use a nebulizer or metered-dose inhaler, as appropriate
possible adverse effects of medications, such as shakiness, palpitations, restlessness, sweating, flushing, and CNS stimulation with bronchodilators
how to perform coughing and diaphragmatic breathing exercises
how to perform pursed-lip breathing to help expel trapped carbon dioxide
relaxation and stress management techniques and positive coping strategies
energy-conservation techniques
signs and symptoms of acid-base imbalance and when to notify the practitioner
home oxygen therapy, if indicated.

Discharge Planning

Participate as part of a multidisciplinary team to coordinate discharge planning efforts. This team may include a bedside nurse, care manager, respiratory therapist, nutritionist, physical therapist, pulmonologist, and primary care practitioner.
Assess the patient's and family's understanding of the diagnosis, treatment, follow-up, and warning signs for which to seek medical attention.
Assess the patient's level of independence before admission.
Evaluate how the current illness will impact the patient's independence.
Identify the patient's formal and informal supports.
Identify the patient's and family's goals, preferences, comprehension, and concerns about discharge.
Confirm arrangements for transportation to initial follow-ups.
Provide a list of prescribed drugs, including the dosage, prescribed time schedule, and adverse reactions to report to the practitioner. Provide the patient (and family or caregiver, as needed) with written information on the medications that the patient should take after discharge.
Assess the patient's and family's understanding of prescribed medication, including dosage, administration, expected results, duration, and possible adverse effects.
Assess the patient's ability to obtain medications; identify the party responsible for obtaining medications.
Instruct the patient to provide a list of medications to the practitioner who will be caring for the patient after discharge; to update the information when the practitioner discontinues medications, changes doses, or adds new medications (including over-the-counter products); and to carry a medication list that contains all of this information at all times in the event of an emergency.
Assist with arrangement of home health care, if needed.
Provide information on smoking cessation, if appropriate.
Ensure that the patient and caregivers receive medical contact information.
Ensure that the patient or caregiver receives a copy of the discharge instructions and that a copy is placed in the patient's medical record.
Assess the patient's and family's understanding of teaching by using the teach-back method when possible.
Document the discharge planning evaluation in the patient's clinical record, including who was involved in discharge planning and teaching, their understanding of teaching provided, and any need for follow-up teaching.