eMedicine Specialties > Pulmonology > Acid-Base Disorders
Respiratory Acidosis: Treatment & Medication
Updated: Apr 2, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Medical Care
The treatment of respiratory acidosis is primarily directed at correcting the underlying disorder. Caution should be exercised when correcting chronic hypercapnia. Rapid correction of the hypercapnia can result in metabolic alkalemia. Alkalinization of the cerebrospinal fluid can result in seizures.
- Infusion of sodium bicarbonate is rarely indicated. This measure may be considered after cardiopulmonary arrest with an extremely low pH (<7.0-7.1). In most other situations, sodium bicarbonate has no role in the treatment of respiratory acidosis.
- Bronchodilators such as beta-agonists (eg, albuterol, salmeterol), anticholinergic agents (eg, ipratropium bromide, tiotropium), and methylxanthines (eg, theophylline) are helpful in treating patients with obstructive lung disease and severe bronchospasm. Theophylline may improve diaphragm muscle contractility and may stimulate the respiratory center.
- Treatment also should be aimed at assisting or increasing ventilation. Therapeutics that may be life saving include endotracheal intubation with mechanical ventilation and noninvasive positive-pressure ventilation (NIPPV) techniques such as nasal continuous positive-pressure ventilation and nasal bilevel ventilation. The later techniques are preferred treatment for obesity-hypoventilation syndrome and neuromuscular disorders because they help improve PaO2 and decrease PaCO2. A study comparing noninvasive techniques with invasive ventilation in myasthenic crisis found that patients had better outcomes with noninvasive ventilation compared with patients who had invasive ventilation.6
- A 4-year retrospective study reported that NIPPV is highly beneficial in the treatment of COPD with hypercapnia (type II) respiratory failure. NIPPV led to decreased length of stay and cost of hospitalization.7
- Noninvasive, external, negative-pressure ventilation devices are available for the treatment of selected patients with chronic respiratory failure.
- Drug therapy aimed at reversing the effects of certain sedative drugs may be helpful in the event of an overdosage. Naloxone (Narcan) may be used to reverse the effects of narcotics. Flumazenil (Romazicon) may be used to reverse the effects of benzodiazepines. Care must be used when reversing the effects of benzodiazepines. Patients may have seizures if benzodiazepine reversal is accomplished too vigorously.
- Oxygen therapy may be indicated because many patients with hypercapnia also are hypoxemic. Oxygen therapy is indicated to prevent the sequelae of long-standing hypoxemia.
- Patients with COPD who meet the criteria for oxygen therapy have been shown to have decreased mortality when treated with oxygen.
- Oxygen therapy has been shown to reduce pulmonary hypertension.
- Oxygen therapy should be used with caution because it may worsen hypercapnia in some situations. Patients with COPD may develop worsening of hypercapnia following oxygen therapy. This observation is thought by many to be primarily a consequence of ventilation-perfusion mismatching. This is opposed to the commonly accepted concept of a reduction in hypoxic ventilatory drive. The exact pathophysiology remains controversial.
- Hypercapnia is best avoided by titration of oxygen delivery to maintain oxygen saturations in the low 90% range and a PaO2 of 60-65 mm Hg.
- Respiratory stimulants have been used but have limited efficacy in respiratory acidosis caused by disease.
- Medroxyprogesterone increases the central respiratory drive and is effective in treating obesity-hypoventilation syndrome.
- Acetazolamide is a diuretic that increases bicarbonate excretion and causes a metabolic acidosis. The metabolic acidosis subsequently stimulates ventilation.
- Theophylline increases diaphragm muscle strength and stimulates the central ventilatory drive.
Surgical Care
- In severe kyphoscoliosis, spine fusion is sometimes indicated for angles greater than 40°.
- Patients with obesity-hypoventilation syndrome might benefit from weight reduction surgery. Bariatric surgical techniques, including vertical banded gastroplasty, adjustable gastric banding, and roux-en-Y gastric bypass, can be offered to these patients. Roux-en-Y gastric bypass is gaining more acceptance because it is performed laparoscopically and because it has better short- and long-term outcomes.
- According to the US National Institutes of Health consensus statement guidelines, surgery should be recommended to patients with a body mass index greater than 35 kg/m2 and an obesity-related comorbid condition (including obesity-hypoventilation syndrome) or patients with a body mass index greater than 40 kg/m2.
- Diaphragmatic pacing can be performed for the treatment for primary alveolar hypoventilation. One study reported that diaphragmatic pacing is an effective treatment of congenital central alveolar hypoventilation syndrome (Ondine curse). This is performed through bilateral axillary thoracotomy.8
Consultations
Consider consultation with pulmonologists and neurologists for assistance with the evaluation and treatment of respiratory acidosis. Results from the history, physical examination, and available laboratory studies should guide the selection of the subspecialty consultants.
Medication
No drugs are used to specifically treat respiratory acidosis. Medical therapies are directed at the underlying disease or disorder causing hypoventilation and, therefore, respiratory acidosis.
Bronchodilators
These agents decrease muscle tone in both small and large airways in the lungs, increasing ventilation. This category includes beta-adrenergics, methylxanthines, and anticholinergics.
Albuterol (Proventil Ventolin)
Beta-agonist for bronchospasm that is refractory to epinephrine. Relaxes bronchial smooth muscle by its action on beta2-receptors, with little effect on cardiac muscle contractility.
Adult
2-4 mg per dose PO divided tid/qid; not to exceed 32 mg/d
MDI: 1-2 puffs q4-6h; not to exceed 12 inhalations per d
Nebulizer: Dilute 0.5 mL (2.5 mg) of 0.5% inhalation solution in 1-2.5 mL of NS; administer 2.5-5 mg q4-6h diluted in 2-5 mL sterile saline or water via nebulizer
Pediatric
<2 years: Not established
2-5 years: 0.1-0.2 mg/kg/dose PO divided tid; not to exceed 12 mg/d
5-12 years: 2 mg/dose PO divided tid/qid; not to exceed 24 mg/d
>12 years: Administer as in adults
MDI
<12 years: 1-2 inhalations qid with tube spacer
>12 years: Administer as in adults
Nebulizer
<5 years: Dilute 0.25-0.5 mL (1.25-2.5 mg) of 0.5% inhalation solution in 1-2.5 mL of NS and administer q4-6h in equally divided doses
>5 years: Administer as in adults
Beta-adrenergic blockers antagonize effects; inhaled ipratropium may increase duration of bronchodilatation by albuterol; cardiovascular effects may increase with MAOIs, inhaled anesthetics, TCAs, and sympathomimetic agents
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in hyperthyroidism, diabetes mellitus, and cardiovascular disorders
Metaproterenol (Alupent, Metaprel)
Beta2-adrenergic agonist that relaxes bronchial smooth muscle with little effect on heart rate.
Adult
0.3 mL of 5% solution diluted in 2.5 mL of 0.45% or 0.9% NS nebulized over 5-15 min q4h
Pediatric
0.1-0.2 mL of 5% solution diluted in 3 mL of 0.45% or 0.9% NS over 5-15 min q4h
Decreases effect of beta-receptor blockers; increases toxicity of MAOIs, TCAs, and sympathomimetics
Documented hypersensitivity; arrhythmia associated with tachycardia
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in hypertension, cardiovascular disease, congestive heart failure, hyperthyroidism, diabetes, and seizures; not recommended for breastfeeding mothers; adverse reactions include tachycardia, headache, nervousness, dizziness, tremor, gastrointestinal upset, hypertension, paradoxical bronchospasm, and cough
Ipratropium (Atrovent)
Anticholinergic bronchodilator chemically related to atropine.
Adult
MDI: 2-4 puffs q4-6h
Nebulizer: 250 mcg diluted with 2.5 mL NS q4-6h
Pediatric
MDI: 1-2 puffs tid; not to exceed 6 puffs per d
Nebulizer: 250 mcg diluted with NS tid
Drugs with anticholinergic properties (eg, dronabinol) may increase toxicity; albuterol may increase effects
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in narrow-angle glaucoma, prostatic hypertrophy, or bladder neck obstruction
Theophylline (Aminophyllin, Theo-24, Theolair, Theo-Dur, Slo-bid)
Potentiates exogenous catecholamines. Stimulates endogenous catecholamine release and diaphragmatic muscular relaxation, which, in turn, stimulates bronchodilation. Popularity has decreased because of narrow therapeutic range and frequent toxicity.
Therapeutic range is 10-20 mg/dL, but bronchodilation may require near-toxic (>20 mg/dL) levels. Clinical efficacy is controversial, especially in the acute setting.
Adult
Initial: 10 mg/kg/d PO divided q8-12h; 5.6 mg/kg loading dose IV over 20 min (based on aminophylline), followed by maintenance infusion of 0.1-1.1 mg/kg/h
Maintenance: 10 mg/kg/d PO qd or divided bid; adjust dose in increments of 25% to maintain serum theophylline level of 5-15 mcg/mL; not to exceed 800 mg/d
Pediatric
<6 weeks: Not established
6 weeks to 6 months: 0.5 mg/kg/h loading dose IV in first 12 h (based on aminophylline), followed by maintenance infusion of 12 mg/kg/d; may administer continuous infusion by dividing total daily dose by 24 h
6 months to 1 year: 0.6-0.7 mg/kg/h loading dose IV in first 12 h, followed by maintenance infusion of 15 mg/kg/d; may administer as continuous infusion, as above
>1 year: Administer as in adults
Aminoglutethimide, barbiturates, carbamazepine, ketoconazole, loop diuretics, charcoal, hydantoins, phenobarbital, phenytoin, rifampin, isoniazid, and sympathomimetics may decrease effects; effects may increase with allopurinol, beta-blockers, ciprofloxacin, corticosteroids, disulfiram, quinolones, thyroid hormones, ephedrine, carbamazepine, cimetidine, erythromycin, macrolides, propranolol, and interferon
Documented hypersensitivity; uncontrolled arrhythmias; peptic ulcers; hyperthyroidism; uncontrolled seizure disorders
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in patients with peptic ulcer, hypertension, tachyarrhythmias, hyperthyroidism, and compromised cardiac function; do not inject IV solution >25 mg/min; patients diagnosed with pulmonary edema or liver dysfunction are at greater risk of toxicity because of reduced drug clearance
Tiotropium (Spiriva)
A quaternary ammonium compound. Elicits anticholinergic/antimuscarinic effects with inhibitory effects on M3 receptors on airway smooth muscles, leading to bronchodilation. Available in cap form containing a dry powder for oral inhalation via HandiHaler inhalation device. Helps patients with COPD by dilating narrowed airways and keeping them open for 24 h.
Adult
Inhale contents of 1 cap (18 mcg) via HandiHaler device qd
Pediatric
Not established
Coadministration with other anticholinergic-containing drugs (eg, ipratropium) may increase toxicity risk
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
For maintenance treatment only; not effective for acute (rescue) therapy of bronchospasm; discontinue use and consider other treatments if immediate hypersensitivity reactions (including angioedema) or paradoxical bronchospasm occur; caution with narrow-angle glaucoma, prostatic hyperplasia, or bladder neck obstruction; commonly causes dry mouth; may cause constipation, increased heart rate, blurred vision, glaucoma, and urinary difficulty or retention; monitor patients with moderate-to-severe renal impairment
Benzodiazepine antagonists
Used in reversing the CNS-depressant effects of benzodiazepine overdose. Ability to reverse the benzodiazepine-induced respiratory depression is less predictable.
Flumazenil (Romazicon)
Reverses effects of benzodiazepines in an overdose by selectively antagonizing the GABA/benzodiazepine receptor complex. If overdosed patient has not responded after 5 min of administering a cumulative dose of 5 mg, cause of sedation likely not benzodiazepines. Short acting, with a half-life of 0.7-1.3 h. However, because most benzodiazepines have longer half-lives, multiple doses should be administered so that patients do not relapse into sedative state.
Adult
0.2 mg IV initially over 30 seconds, repeat at 1-min intervals with 0.5 mg over 30 seconds until satisfactory response is attained or 3 mg is administered; may require additional titration to a total 5 mg
Pediatric
0.01 mg/kg IV initially over 15 seconds, repeat at 1-min intervals with 0.005-0.01 mg/kg; not to exceed 0.2 mg per dose
Caution in cases of mixed-drug overdose; toxic effects due to other drugs taken in overdose (eg, TCAs) may occur with reversal of benzodiazepine effects
Documented hypersensitivity; serious cyclic antidepressant overdosage; patients administered a benzodiazepine for control of potentially life-threatening condition (eg, intracranial pressure, status epilepticus)
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Monitor for resedation (at least 2 h), respiratory depression, seizures, or other benzodiazepine residual effects; caution in drug or alcohol dependence, head injury, hepatic disease, and panic disorder; patients on benzodiazepines for prolonged periods may experience seizures
Opioid antagonists
Opioid abuse, toxicity, and overdose are potential etiologies of hypoventilation and respiratory acidosis. Can be used to reverse the effects of opiates and to improve ventilation.
Naloxone (Narcan)
Pure opioid antagonist. Prevents or reverses opioid effects (eg, hypotension, respiratory depression, sedation), possibly by displacing opiates from their receptors. Used to reverse opioid intoxication.
Adult
0.4-2 mg IV/IM/SC q2-3min prn; use increments of 0.1-0.2 mg in patients who are opioid dependent; may need to repeat dose q20-60min; if no response observed after administering 10 mg, question the diagnosis
Pediatric
0.1 mg/kg IV/IM/SC, repeat q2-3min prn
Decreases analgesic effects of narcotics
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in cardiovascular disease; may precipitate withdrawal symptoms in patients who are addicted to opiates
More on Respiratory Acidosis |
| Overview: Respiratory Acidosis |
| Differential Diagnoses & Workup: Respiratory Acidosis |
 Treatment & Medication: Respiratory Acidosis |
| Follow-up: Respiratory Acidosis |
| References |
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Further Reading
Keywords
respiratory acidosis, hypoventilation, hypercapnia, alveolar hypoventilation, impaired ventilation, central respiratory depression, myasthenia gravis, amyotrophic lateral sclerosis, Guillain-Barre syndrome, muscular dystrophy, asthma, airway obstruction, chronic obstructive pulmonary disease, COPD, increased ventilation-perfusion mismatch, decreased diaphragm function, diaphragm dysfunction, obesity hypoventilation syndrome, obesity-hypoventilation syndrome, pickwickian syndrome, respiratory muscle fatigue, emphysema, chronic bronchitis, bronchitis, amyotrophic lateral sclerosis, diaphragm paralysis, kyphoscoliosis
