It also decreases coronary blood flow and predisposes persons to refractory arrhythmias. This condition may also cause hypoventilation, leading to hypoxemia and impair weaning from mechanical ventilation. This is also associated with hypokalemia and may precipitate hepatic encephalopathy in susceptible patients. Third simple acid-base disorder is respiratory acidosis. This is a clinical disturbance due to alveolar hypoventilation. The production of carbon dioxide increases and there is a failure of ventilation, which increases the partial arterial pressure of carbon dioxide. This in turn decreases the HCO3-/PaCO2 and decreases pH. This condition can either be acute or chronic. Acute respiratory acidosis occurs when an abrupt failure of ventilation occurs, whereas, chronic respiratory acidosis may be secondary to many disorders, including COPD. This disorder can be manifested depending on the severity and on the rate of development of hypercapnia. Patients either present with anxiety and dyspnea or sleep and daytime hypersomnolence. anxiety may progress to delirium, and patients become progressively more confused, somnolent, and obtunded or sometimes called as CO2 narcosis. Respiratory acidosis may be caused by chronic obstructive pulmonary disease, neuromuscular diseases, obesity hypoventilation syndrome or CNS depression due to drugs, neurologic disorders or primary alveolar hypoventilation.

This disorder is treated primarily by correcting the underlying disorder, like the other acid-base disorders. But caution is exercised because rapid correction of the hypercapnia can cause alkalanization of the CSF which can cause seizures and metabolic alkalemia. Other forms of treatment include infusion of sodium bicarbonate, but this is rarely indicated. Some give bronchdilators, but treatment is aimed at assisting or increasing ventilation or drugs aimed at reversing the effects of certain sedative drugs also may be helpful in the event of an overdosage. Oxygen therapy and respiratory stimulants have been used...

This acid-base disorder is the most common among critically ill patients and is associated with numerous diseases and is commonly seen with patients in mechanical ventilation. On physical examination this condition can present nonspecifically and is related to the underlying illness or cause of the disorder. Many patients are anxious, tachycardic and tachypneic. There may also be positive Chvostek and Trousseau signs.
Treatment of respiratory alkalosis is also focused on the treatment of the underlying disorder that causes the acid-base imbalance. But this condition is rarely life threatening, therefore immediate treatment is not indicated unless the pH level is greater than 7.5 and treatment is usually unsuccessful unless the stimulus is controlled. If there is rapid correction of PaCO2 in patients with chronic respiratory alkalosis, metabolic acidosis may develop. In patients on mechanical ventilation, improvement is seen when tidal volume and respiratory rate is decreased. In hyperventilation syndrome, patients should be reassured and rebreathing into a paper bag is done.

Kasper, et. al., Harison's Principles of Internal Medicine 16th ed., Manual of Medicine. McGraw-Hill, 2005., p. 9-14.

Jackie a Hayes, MD, FCCP, Respiratory Alkalosis. E-medicine. 2005. (http://www.emedicine.com/MED/topic2009.htm)

Jackie a Hayes, MD, FCCP, Respiratory Acidosis. E-medicine. 2005. (http://www.emedicine.com/med/TOPIC2008.htm)

Sameer Yaseen, MD, Metabolic Alkalosis. E-medicine. 2007. (http://www.emedicine.com/med/TOPIC1459.htm)

Karen L. Stavile, MD, Metabolic Acidosis. E-medicine. 2005. (http://www.emedicine.com/emerg/topic312.htm)