A respiratory acidosis is a primary increase in Carbondioxid partial pressure (PCO2) with or without a compensatory increase of bicarbonate (HCO3-); the pH is usually low, but may be almost normal. The cause is a decrease in respiratory rate and / or tidal volume (hypoventilation), typically by iatrogenic disorders of the central nervous system, the lungs or under measures. A respiratory acidosis can be acute or chronic. The chronic form is asymptomatic, but acute or worsening acidosis leads to headaches, confusion and dizziness. Other symptoms include tremors, myoclonic jerks and asterixis. The diagnosis is clinical and with ABG and measurement of serum electrolytes. The underlying cause is treated. Often the administration of oxygen (O2) or mechanical ventilation is necessary.

(See also acid-base regulation and acid-base disturbances).

A respiratory acidosis is a primary increase in Carbondioxid partial pressure (PCO2) with or without a compensatory increase of bicarbonate (HCO3-); the pH is usually low, but may be almost normal. The cause is a decrease in respiratory rate and / or tidal volume (hypoventilation), typically by iatrogenic disorders of the central nervous system, the lungs or under measures. A respiratory acidosis can be acute or chronic. The chronic form is asymptomatic, but acute or worsening acidosis leads to headaches, confusion and dizziness. Other symptoms include tremors, myoclonic jerks and asterixis. The diagnosis is clinical and with ABG and measurement of serum electrolytes. The underlying cause is treated. Often the administration of oxygen (O2) or mechanical ventilation is necessary. (See also acid-base regulation and acid-base disturbances.) A respiratory acidosis is the accumulation of Carbondioxid (CO2) (hypercapnia) due to a decrease in respiratory rate and / or tidal volume (hypoventilation). Causes of hypoventilation (discussed below ventilatory insufficiency) include health conditions that affect the respiratory drive of the CNS health conditions that affect the neuromuscular transmission, and other conditions, the muscle weakness cause obstructive, restrictive and parenchymal lung disease Hypoxia is typically associated with hypoventilation. A respiratory acidosis can be acute or chronic. The distinction is based on the degree of metabolic compensation. CO2 is first adequately buffered, but after 3-5 days increase the kidneys HCO3 – reabsorption rate significantly. Symptoms and signs The symptoms and discomfort depend on the speed and level of PCO2 rise. CO2 diffuses rapidly through the blood-brain barrier. The symptoms and complaints are the result of a high central nervous CO2 concentration (low pH central nervous system) and an accompanying hypoxemia. Acute (or acutely deteriorating chronic) respiratory acidosis causes headaches, confusion, anxiety, dizziness and stupor (CO2 narcosis). A slowly developing, stable respiratory acidosis (as in COPD) can be very well tolerated, yet many patients suffer from memory – and sleep disorders, severe daytime fatigue and personality changes. The clinical signs are gait disturbances, tremor, weakened deep tendon reflexes, myoclonic jerks, asterixis and papilledema. Clinical calculator: Arterial blood gas interpretation TreeCalc diagnosis ABG and serum electrolytes The diagnosis of the cause is clinical In general, the diagnostic criteria for a respiratory acidosis and the corresponding renal compensation (acid-base disorders: diagnostic) require ABG and measurement of serum electrolytes. The causes are usually easy to derive from the history and the results of the physical examination. The calculation of the alveolar-arterial (A-a) OO2 gradient (inspiratory PO2 – [arterial Po2 + 5/4 arterial PCO2]) can be helpful in distinguishing between a pulmonary disease and a extrapulmonary. A normal gradient exclude pulmonary disease substantially. Clinical calculator: A-a gradient treatment Adequate ventilation sodium bicarbonate (NaHCO3) almost always contraindicated The therapy is to ensure adequate ventilation – either by means of endotracheal intubation or non-invasive positive pressure ventilation (special indications and techniques, respiratory failure at a Glance). Adequate ventilation is all that is needed for a correction of respiratory acidosis. However, a chronic hypercapnia should be corrected generally slow (z. B. over several hours or slower), because too rapid lowering of PCO2eine posthyperkapnische “excessive” alkalosis can trigger, if the underlying compensatory Hyperbikarbonatämie is unmasked. The resulting sudden rise in the central nervous pH can lead to seizures and death. Any potassium and chloride – deficiencies must be balanced. Sodium bicarbonate is almost always contraindicated because of the potential for paradoxical acidosis in the CNS. An exception may be cases of severe bronchospasm, where HCO3- improved under certain circumstances the response of the bronchial smooth muscle of beta-agonists. Summary An respiratory acidosis with a decrease in respiratory rate and / or tidal volume associated (hypoventilation). Common causes include an impaired respiratory drive (eg. As a result of toxins, CNS disease) and an airway obstruction (eg. As a result of asthma, COPD, sleep apnea, Atemwegsödem). Chronic hypoventilation is in the presence of metabolic compensation (increased HCO3-) and clinical signs of tolerance (less drowsiness and confusion, as would be expected for the degree of hypercapnia) to detect. Treat the cause and provide for an adequate ventilation means of intubation or non-invasive positive pressure ventilation required.

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