Respiratory acidosis resident survival guide
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Qasim Khurshid.M.B.B.S
Overview
Causes
Life Threatening Causes
Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.
- Sedative overdose (eg, narcotic or benzodiazepine, some anesthetics, tricyclic antidepressants)
- Epiglottitis
- Foreign body aspiration
- Angioedema
- Pulmonary embolism (usually severe)
- Respiratory muscle fatigue
- Periodic paralysis
- Phrenic nerve injury
- Organophosphates poisoning
- Procainamide toxicity
Common Causes
- Sedative overdose (eg, narcotic or benzodiazepine, some anesthetics, tricyclic antidepressants)
- Encephalitis
- Brainstem disease
- Central and obstructive sleep apnea
- Amyotrophic lateral sclerosis
- Dynamic hyperinflation (eg, upper and lower airway disorders including chronic obstructive pulmonary disease, severe asthma)
- Endstage interstitial lung disease
- Pulmonary embolism (usually severe)
- Thyrotoxicosis
- Foreign body aspiration
- Retropharyngeal disorders
- Obstructive goiter
- Vocal cord paralysis
- Hypophosphatemia
- Hypomagnesemia
- Hyperthyroidism
- Tetanus
- Botulism
- Succinylcholine and neuromuscular blockade
Diagnosis
Shown below is an algorithm summarizing the diagnosis of respiratory acidosis.
| Suspected acid base disorder | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Acidemia pH<7.35 | Normal pH | Alkalemia pH>7.45 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Metabolic acidosis HCO3<24mmol/L CO2:HCO3 12:10 | Respiratory acidosis pCO2>40mmHg | Metabolic alkylosis HCO3>28mmol/L CO2:HCO3 7:10 | Respiratory alkylosis pCO2<35mmHg | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Anion gap | Non anion gap | Acute CO2:HCO3 10:1 | Chronic CO2:HCO3 10:3 | Acute CO2:HCO3 10:2 | Chronic CO2:HCO3 10:4 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Appropriate compensation Ratio(CO2:HCO3) Metabolic acidosis 12:10 Metabolic alkylosis 7:10 Acute respiratory acidosis 10:1 Chronic respiratory acidosis 10:3 Acute respiratory alkylosis 10:2 Chronic Respiratory alkylosis 10:4 | |||||||||||||||||||||||||||||||||||||||||||||||||||
Treatment
Shown below is an algorithm summarizing the treatment of acute respiratory acidosis.
| Apnea or Respiratory distress(of recent onset) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| {{{ }}} | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Airway patency scured | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | NO | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Oxygen-rich mixture delivered | Airway patent | Remove dentures,foreign bodies, or food particles Consider tracheal intubation | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mental status and blood gas evaluated | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patient alert, Blood pH>7.10 or PaCO2<80mmHg | Patient obtunded,Blood pH<7.10 or PaCO2>80mmHg | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Administer O2 via nasal mask or prongs to maintain pO2>60mmHg Correct reversible causes of pulmonary dysfunction with antibiotics,bronchodilators,and corticosteriods as needed Monitor patient with abnormal arterial blood gases at 20-30 minutes of interval initially and less frequently thereafter If PaO2 does not increase to >60mmHg or PaCO2 rises to >80mmHg,proceed to therapy for obtunded | Consider use of non invasive ventilation through a nasal or full face mask Consider intubation or initiation of mechanical ventilation if non invasive ventilation fails or contraindicated If arterial pH<7.10 on ventilatory support, administer sodium bicarbonate to maintain blood pH between 7.10 to 7.20 Correct reversible causes of pulmonary dysfunction with antibiotics,bronchodilators,and corticosteriods as needed | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Do's
- The content in this section is in bullet points.
Don'ts
- The content in this section is in bullet points.