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Respiratory Acidosis

Acidosis Hypercapneic

Respiratory acidosis is characterized by hypoventilation which causes the concentration of carbon dioxide in the body to rise which is accompanied by a decrease in pH.


Individuals with respiratory acidosis experience anxiety, restlessness, blurred vision and headache. In addition, they also experience shortness of breath along with lethargy and fatigue. In more advanced stages, affected individuals show signs of neurologic abnormalities characterized by delirium, asterixis, development of tremors and somnolence [7]. In severe cases, the individual can even go into a coma. Severe hypercapnia may set in which increases the cerebral blood flow and the intracranial pressure leading to the development of papillemdema [8].

  • POP was suspected on the basis of fever, radiographic infiltrate, and either leucocytosis or purulent sputum. The diagnosis was confirmed by culture of a respiratory sample.[ncbi.nlm.nih.gov]
Purulent Sputum
  • POP was suspected on the basis of fever, radiographic infiltrate, and either leucocytosis or purulent sputum. The diagnosis was confirmed by culture of a respiratory sample.[ncbi.nlm.nih.gov]
  • Esophageal distension induces cSC/nucleus ambiguus/vagovagal reflex relaxation of the upper esophageal sphincter and CO(2) is vented into the pharynx and mixed with pulmonary gas during expiration or, alternatively, during eructation.[ncbi.nlm.nih.gov]
  • Abstract An 87-year-old female, with a history of hypertension controlled with hydrochlorothiazide, was scheduled for excision of a cystic mass of the left lobe of the thyroid.[ncbi.nlm.nih.gov]
  • Pulmonary hypertension -- high blood pressure within the lungs -- can result from long-term untreated hypoxemia.[livestrong.com]
  • Chronic hypoxemia can also cause narrowing of pulmonary arteries, which may increase blood pressure in the arteries of the lungs (pulmonary hypertension). This may result in heart failure.[healthhype.com]
  • Tachycardia develops early because the sympathetic nervous system is stimulated, resulting in the release of catecholamines, epinephrine, and norepinephrine, in an attempt to increase oxygen delivery to the tissues.[nurseslabs.com]
  • Tachycardia develops early because the sympathetic nervous system is stimulated, resulting in the release of catecholamines, epinephrine , and norepinephrine , in an attempt to increase oxygen delivery to the tissues.[nurseslabs.com]
  • , mild to profound May exhibit: Generalized weakness, ataxia/staggering, loss of coordination (chronic), to stupor CIRCULATION May exhibit: Low BP/ hypotension with bounding pulses, pinkish color, warm skin (reflects vasodilation of severe acidosis) Tachycardia[nurseslabs.com]
  • […] initial signs; muscle twitching, tremors, seizures, and coma can ensue; rapid respirations initially and then decreased due to adaptation; vasodilation due to acidosis (CO2 is a vasodilator), therefore the skin might be pink, unless there is hypoxemia; tachycardia[m2hnursing.com]
  • A 56-year-old woman with a history of paraplegia and chronic pain due to neuromyelitis optica (Devic's syndrome) was admitted to a spinal cord injury unit for management of a sacral decubitus ulcer.[ncbi.nlm.nih.gov]
  • Moreover, coordination of respiratory and digestive control networks through the cSC could also account for the frequent co-expression of pulmonary diseases that cause chronic respiratory acidosis (and overstimulation of cSC neurons) with peptic ulcer[ncbi.nlm.nih.gov]


The following diagnostic tools are employed for evaluating the condition of respiratory acidosis:

  • Laboratory tests: Measuring the arterial blood gas forms the basis of the diagnosis. This is required to measure the levels of carbon dioxide and oxygen in the blood. Following this, serum bicarbonate levels should also be evaluated along with complete blood count and thyroid studies [9].
  • Radiography: Chest x – ray should be carried out to rule out pulmonary disease. Fluoroscopy may also be required in addition to chest radiographs to diagnose diaphragmatic paralysis.
  • Imaging studies: Imaging studies such as CT (computerized tomography) scan and MRI (Magnetic resonance imaging) are required when radiographs do not provide conclusive results. CT scan provides more useful results for diagnosing pulmonary disease. MRI is done when CT scan results are inconclusive.
  • Pulmonary lung function tests: These are done to diagnose the condition of chronic obstructive pulmonary disease.
  • The cause was attributed to subcutaneous insufflation and absorption of CO2, directly related to the surgical pneumoperitoneum.[ncbi.nlm.nih.gov]
  • Moderate hypercapnia had no effect on these parameters.[ncbi.nlm.nih.gov]
  • Hypercapnia and respiratory acidosis ensue when impairment in ventilation occurs and the removal of carbon dioxide by the respiratory system is less than the production of carbon dioxide in the tissues.[emedicine.com]
  • Hypocapnia was produced by deliberate hyperventilation and hypercapnia by adding carbon dioxide to the inspired gas mixture. 2.[ncbi.nlm.nih.gov]
  • Abstract Hypercapnia due to respiratory failure can be more severe when accompanied by coexistent metabolic alkalosis.[ncbi.nlm.nih.gov]
Bicarbonate Increased
  • Measurement of the serum bicarbonate permits definitive diagnosis: acute respiratory acidosis: serum bicarbonate increases by 1 mmol/l for each 10 mmHg (or 1.33kPa) increase in PaCO2 chronic respiratory acidosis: serum bicarbonate increases by 3.5 mmol[gpnotebook.co.uk]
  • increase was not calculated using theoretical equations estimating protein or phosphate buffering, but was derived from empirical measurements of the changes in bicarbonate occuring in healthy volunteers.[derangedphysiology.com]
  • They found that bicarbonate increased by 5.1 mmols/l for every 10mmHg pCO2 rise.[anaesthesiamcq.com]
Chloride Decreased
  • Serum chloride: Decreased. Serum calcium: Increased. Lactic acid: May be elevated. Urinalysis: Urine pH decreased. Other screening tests: As indicated by underlying illness/condition to determine underlying cause.[nurseslabs.com]
  • Members of the Enterobacteriaceae and Pseudomonas species were the most frequently identified pathogens.[ncbi.nlm.nih.gov]


Treatment of acute respiratory acidosis involves preliminary correction of the underlying condition. The airway should be cleared so that the volatile fractions can get gradually excreted.

Chronic respiratory acidosis can be treated by clearing the airway passage and managing underlying diseases.

Bronchodilators may have to be administered for expanding the air passage. In addition, antibiotics will also be required for treating infections. These are given along with diuretics in order to decrease the pressure on the heart and lungs and corticosteroids are given for reducing the inflammation. In severe cases, the individuals would have to be put on ventilator [10].


The prognostic factor for individuals with respiratory acidosis largely depends on the underlying causative factor and the severity of the disease. If the underlying disease can be successfully treated, then the condition of respiratory acidosis can be corrected as well. In such cases, the prognosis of the condition is pretty good [6].


Sudden ventilation failure is the major cause of acute respiratory acidosis. This type of condition occurs due to depression that occurs in the central respiratory region by cerebral diseases. In addition, drugs, obstruction of the airways, asthma and chronic obstructive pulmonary disease can also favor ventilation failure causing acute respiratory acidosis. Certain other disease conditions such as myasthenia gravis, muscular dystrophy and amyotrophic lateral sclerosis can also lead to acute respiratory failure [2].

Chronic respiratory acidosis occurs as a secondary phenomenon to other disease conditions such as Pickwickian syndrome, various neuromuscular diseases and ventilator defects [3].


The exact prevalence of respiratory acidosis is unknown. However, it has been reported that patients with chronic obstructive pulmonary disease are prone to develop respiratory acidosis. In a one year prospective study carried out during the years 1997 -1998, the relationship between respiratory acidosis and oxygenation was explained. The results revealed that of 983 patients that were admitted to the hospital, 972 suffered from respiratory acidosis. Such patients require non-invasive ventilation in order to correct the condition of acidosis. From the available data, it can be estimated that of the 90 patients that would be admitted to UK hospitals every year, 72 cases would be that of respiratory acidosis [4].

Sex distribution
Age distribution


Under normal physiological conditions, metabolic processes generate huge amounts of volatile as well as nonvolatile acid. In addition to this phenomenon, metabolism of fats and carbohydrates also produces large amounts of carbon dioxide.

The carbon dioxide combines with water leading to the formation of carbonic acid. If the lungs function in the normal fashion, then the carbonic acid is readily excreted through the process of ventilation. Such a phenomenon, therefore does not favor the accumulation of acid. Conditions or processes that interfere with the normal ventilation process can disturb the excretion of volatile fraction which in turn would cause acid accumulation in the body [5].


Avoiding smoking can go a long way in preventing the onset of lung disorders, which may in turn pave way for development of respiratory acidosis. Obesity induced respiratory acidosis can be prevented by keeping weight under check. Individuals are also advised against taking medications that induce sedation; moreover, they should never be combined with alcohol.


Respiratory acidosis can be either acute or chronic in nature. In this type of acidosis, there is an excessive buildup of carbon dioxide in the body due to the inability of the lungs to remove the excess carbon dioxide. Respiratory acidosis is defined by an arterial pH of less than 7.36 and an increase in pCO2 and HCO3- [1]. It is an emergency situation, requiring prompt treatment. 

Patient Information

Respiratory acidosis is a condition in which there is is increase in the carbon dioxide concentration in body due to diseases affecting the lungs. Underlying disease conditions such as asthma, chronic obstructive lung disease, diseases of chest, obesity and certain drugs favor the development of respiratory acidosis. Symptoms of respiratory acidosis include breathlessness, fatigue, lethargy and sleepiness. In severe cases, individuals would also experience neurologic symptoms such as delirium, confusion, somnolence and onset of tremors. Treating the underlying disease condition forms the basis of the treatment regime.



  1. Wiseman AC, Linas S. Disorders of potassium and acid-base balance. Am J Kidney Dis. May 2005;45(5):941-9.
  2. West JB. Causes of carbon dioxide retention in lung disease. N Engl J Med 1971; 284:1232.
  3. Berger AJ. Control of breathing. In: Textbook of Respiratory Medicine, 2nd ed, Murray J, Nadel J (Eds), WB Saunders, Philadelphia 1994. p.199
  4. Sorli J, Grassino A, Lorange G, Milic-Emili J. Control of breathing in patients with chronic obstructive lung disease.ClinSciMol Med 1978; 54:295.
  5. Dales RE, Spitzer WO, Schechter MT, Suissa S.The influence of psychological status on respiratory symptom reporting.Am Rev Respir Dis 1989; 139:1459.
  6. Campbell EJ. The J. Burns Amberson Lecture. The management of acute respiratory failure in chronic bronchitis and emphysema.Am Rev Respir Dis 1967; 96:626.
  7. Pollock JM, Deibler AR, Whitlow CT, et al. Hypercapnia-Induced Cerebral Hyperperfusion: An Underrecognized Clinical Entity. AJNR Am J Neuroradiol. Oct 14 2008
  8. Weinberger SE, Schwartzstein RM, Weiss JW. Hypercapnia. N Engl J Med 1989; 321:1223.
  9. Zhang WB, Wang XY, Tian XY, Zhang H, Wang ZP, Gao YY. [Clinical value of noninvasive positive-pressure ventilation in chronic obstruction pulmonary disease combined with type II respiratory failure: a 4-year retrospective study]. Zhongguo Wei Zhong Bing Ji Jiu Yi Xue. Oct 2008;20(10):601-3.
  10. Joosten SA, Koh MS, Bu X, et al.The effects of oxygen therapy in patients presenting to an emergency department with exacerbation of chronic obstructive pulmonary disease. Med J Aust 2007; 186:235.

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Last updated: 2018-06-22 03:14