(PRIMARY CARBONIC ACID DEFICIT)
I. Pathophysiology—acute or chronic increase in respiratory
rate and volume, primarily triggered by hypoxemia or direct
stimulation of the central respiratory center of the brain
a. Acute: PaCO2 is below lower limit of normal, serum pH
is alkalemic due to loss of potassium, and phosphate
secondary to cellular uptake.
b. Chronic: PaCO2 is below the lower limit of normal, but pH
is normal or near normal because of renal compensation.
II. Compensatory Mechanisms—occurs over 2 to 3 days
a. Decreased respiratory rate (if the body is able to respond to
the drop in PaCO2)
b. Increased renal excretion of bicarbonate
c. Retention of hydrogen
a. Alveolar hyperventilation, hypocapnea (PaCO2 less than
35 mm Hg), increased ratio of bicarbonate concentration to
PaCO2 (base excess), near-normal or alkaline pH
b. Most frequently occurring acid-base imbalance in hospitalized
clients, with the elderly being at increased risk because
of the high incidence of pulmonary disorders and
alterations in neurologic status
c. Conditions or disorders associated with respiratory alkalosis:
i. Central nervous system (CNS)—such as stroke, meningitis,
encephalitis, brain trauma or tumor, pain, hyperventilation,
anxiety, psychosis, fever
ii. Hypoxemia—such as severe anemia, any lung disease
that leads to shortness of breath, high altitude
iii. Drugs—such as salicylates, nicotine, methyxanthines,
iv. Endocrine—such as hyperthyroidism, pregnancy,
increased progesterone levels
v. Stimulation of chest receptors—such as pulmonary embolus,
pulmonary edema, aspiration, hemopneumothorax
vi. Miscellaneous—such as sepsis, liver failure, heat exhaustion,
mechanical ventilation (pseudorespiratory alkalosis)
This condition does not occur in isolation, but rather is a
complication of a broader problem. Treatment is primarily
directed at correcting the underlying disorder causing respiratory
alkalosis and is usually found in clients requiring care
in a medical-surgical or subacute unit.
Plans of care specific to predisposing factors, such as:
Anemias—iron deficiency, anemia of chronic disease, pernicious,
Cirrhosis of the liver
Hyperthyroidism (Graves’ disease, thyrotoxicosis)
Fluid and electrolyte imbalances
Heart failure: chronic
Ventilatory assistance (mechanical)
Metabolic acidosis—primary base bicarborate deficiency
Metabolic alkalosis—primary base bicarborate excess
1. Achieve homeostasis.
2. Prevent or minimize complications.
3. Provide information about condition, prognosis, and
treatment needs as appropriate.
1. Physiological balance restored.
2. Free of complications.
3. Condition, prognosis, and treatment needs understood.
4. Plan in place to meet needs after discharge.