Respiratory Alkalosis

Respiratory alkalosis alters the acid-base balance due to alveolar hyperventilation. It can be due to a

• reflex compensation for metabolic acidosis, or it can occur from
• hyperventilation (anxiety, stress, fear).

A decrease in PaCO2 (hypocapnia) develops when a strong respiratory stimulus causes the respiratory system to remove more carbon dioxide than is produced in the tissues from metabolism.

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Respiratory Alkalosis

Respiratory alkalosis (>7.45 pH) is caused by a decreased level of the respiratory acid carbon dioxide in the blood, with an associated increase in bicarbonate.

It can be either

• acute or
• chronic: the compensatory response to acute respiratory alkalosis reduces the serum HCO3 concentration, but If the reduced PCO2 persists for more than 3-5 days, then the disorder is considered chronic.

 

Causes

Common causes of respiratory alkalosis are:

• stress, anxiety, or panic disorders (psychiatric),
• pulmonary disorder,
• thermal insult,
• high altitude,
• aspirin overdose,
• fever,
• vocal cord paralysis,
• liver disease, and
• hyperventilation associated with all of the above.

 

Signs and Symptoms of Respiratory Alkalosis

S&S include:

• palpitations,
• tetany,
• convulsions,
• sweating, and
• anxiety.

Severe cases may cause a temporary loss of consciousness.

NOTE: when panic results in hyperventilation, the resulting symptoms of palpitations and anxiety will only fuel the hyperventilation in a vicious cycle.

 

Management

Treatment includes addressing the underlying cause:

• assisting or managing the rate and/or depth of ventilation,
• sedation,
• oxygen, and
• pain control.

In the field, focus on decreasing the rate and depth of ventilation. (Calm them down or stop bagging so fast.)

 

Hyperventilation Syndrome

DEFINITIONS:

Hyperventilation: Alveolar hyperventilation is present when the arterial tension of carbon dioxide (PaCO2) decreases below the normal range (<36 mm Hg).

Hyperpnea: Increase in the depth and rate of respiration leading to an increase in the minute volume of ventilation (= tidal volume/breath x respiratory rate). An associated increase in metabolism increases CO2 production, as in exercise. (PaCO2 remains normal.)

Tachypnea: Increased respiration > 20/minute.

Hyperventilation Syndrome: respiratory symptoms of

• dyspnea,
• hyperventilation, and
• distress and/or
• anxiety.

Hyperventilation episodes (or "attacks") are frequently associated with panic disorder. The prevalence of hyperventilation syndrome has been reported to range from 25-83% in patients with an anxiety disorder. Whether the psychological condition is primary or secondary is unclear.

S&S of Hyperventilation Syndrome

• Dyspnea (60%)
• Dizziness or lightheadedness (13- 50%)
• Chest pain or tightness (43%)
• Paresthesias (35-60%)
• Palpitations (13%)
• Carpopedal spasm (9%)

Only 17% of patients who are hyperventilating are aware they are hyperventilating.

Hyperventilation syndromes can also result from neurological damage in trauma patients. This is known as "central neurogenic hyperventilation" and will present alongside a diminished mental status as the brain's ability to regulate respiration breaks down.

 

Management

In the field, focus on decreasing the rate and depth of ventilations. (Calm them down or stop bagging so fast.) Reassurance and a calm demeanor are helpful in incidences of panic attack.