Respiratory Alkalosis

Planning

involves identification and treatment of its underlying cause and the restoration of acid-base balance. Appropriate outcomes include resolution of the underlying cause and that the patient will manifest normal respiratory rate and rhythm, maintain safety, and maintain appropriate fluid status.

Respiratory alkalosis

A condition that results when pH rises above 7.45 and PaCO2 falls below 35 mmHg. It is caused by hyperventilation (unusually fast respiration, or overbreathing), leading to a carbon dioxide deficit.

Pharmacologic Therapy

A sedative or antianxiety agent may be necessary to relieve anxiety and restore a normal breathing pattern. Additional drugs may be ordered to correct underlying problems other than anxiety-induced hyperventilation.

Risk Factors

Anxiety with hyperventilation is the most common cause of respiratory alkalosis; therefore anxiety disorders increase the risk for this acid-base imbalance. In the patient who is critically ill, mechanical ventilation is a risk factor for respiratory alkalosis if breaths per minute or peak pressures are set too high for the patient's needs.

Etiology

Anxiety-based hyperventilation is the most common cause of acute respiratory alkalosis. Alkalosis increases binding of extracellular calcium to albumin, reducing ionized calcium levels. As a result, neuromuscular excitability increases, and manifestations similar to hypocalcemia develop. Low carbon dioxide levels in the blood cause vasoconstriction of cerebral vessels, increasing the neurologic manifestations of the disorder.

Planning and teaching for home care

Directed toward the underlying cause of hyperventilation. If anxiety precipitated the episode, discuss anxiety and stress management strategies with the patient. Teach the patient how to identify a hyperventilation reaction and provide self-care, and when to seek medical intervention.

Physical examination

Examine breath sounds, neurologic function, respiratory and cardiac status, and any changes in LOC.

Physiologic causes of hyperventilation

High fever, hypoxia, gram-negative bacteremia, and thyrotoxicosis (excessive amounts of thyroid hormones) Early salicylate intoxication (aspirin overdose), encephalitis, and high progesterone levels in pregnancy directly stimulate the respiratory center, potentially leading to hyperventilation and respiratory alkalosis. Hyperventilation also can occur during anesthesia and mechanical ventilation if the rate and tidal volume (depth) of ventilation are excessive.

Etiology Simplified

Hyperventilation due to: • Brainstem injury • Elevated body temperature or fever • Extreme anxiety • Hypoxia • Increased basal metabolic rate • Overventilation with a mechanical ventilator • Salicylate overdose

Pathophysiology

In acute respiratory alkalosis, the pH rises rapidly as the PaCO2 falls. Because the kidneys are unable to adapt rapidly to the change in pH, the bicarbonate level remains within normal limits.

Manifestations

Include light-headedness, a feeling of panic and difficulty concentrating, circumoral and distal extremity paresthesias (numbness or tingling), tremors, and positive Chvostek sign (a type of facial spasm, usually indicative of hypocalcemia) and Trousseau sign (a spasm of the hand and forearm). The patient also may experience tinnitus, a sensation of chest tightness, and palpitations (cardiac dysrhythmias). Seizures and loss of consciousness may occur. ABGs generally show a pH greater than 7.45 and a PaCO2 of less than 35 mmHg. In chronic hyperventilation, there is a compensatory decrease in serum bicarbonate to less than 24 mEq/L, and the pH may be near normal.

Implementation

It is important not only to address the hyperventilation but also to identify the underlying cause. The usual cause of hyperventilation and respiratory alkalosis is psychologic, although physiologic disorders also can lead to hyperventilation.

Collaboration

Management of respiratory alkalosis focuses on correcting the imbalance and treating the underlying cause. It is important to create a calm, quiet, low-stimulation environment to reduce the patient's anxiety or panic. ABGs must be ordered prior to administration of medications or oxygen therapy.

Respiratory Alkalosis in Older Adults

Many older adults can maintain acid-base balance under normal conditions. Respiratory distress and chest pain are commonly seen in older adults with respiratory alkalosis. Increased PaCO2 excretion from hyperventilation occurs with compensatory response of HCO3 excretion of the kidneys. Hyperventilation in older adults may originate from hypoxia, pulmonary emboli, or anxiety. Inpatient care is usually not required with hyperventilation related to an anxiety disorder. Pharmacotherapy is often helpful but should be used with caution in older adults who take multiple medications. Regardless, it is important to rule out any serious problems, such as encephalitis and septicemia, before discharging older adults. Outcome depends on the nature of the illness and early diagnosis/treatment.

Observation and patient interview

Observe the patient for signs of anxiety. Discuss the triggering event for the onset of hyperventilation. Ask the patient about mental health disorders, coping mechanisms, and available support systems.

Respiratory Therapy

The best treatment for suspected hyperventilation is to teach breathing exercises, encouraging the patient to take slow, regular breaths and breathe into cupped hands. Stress reduction should be strongly encouraged.

Evaluation

The evaluation of care is based on the patient's ability to meet goals set during the planning stage and the outcomes achieved. Nursing care is reformulated as needed if outcomes are not met.

If hyperventilation continues

The kidneys compensate by eliminating bicarbonate to restore the ratio of bicarbonate to carbonic acid. The bicarbonate level is lower than normal in chronic respiratory alkalosis, and the pH may be close to the normal range.

Hyperventilation

Unusually fast respirations, or overbreathing causing an imbalance of oxygen and carbon dioxide.

Paper Bags

Use of paper bags has historically been a recommended treatment for hyperventilation. While use of paper bags helps to raise carbon dioxide levels in patients with true hyperventilation syndrome, it can also cause hypoxia. Other diseases can mimic hyperventilation, such as myocardial infarction, pneumothorax, and pulmonary embolism (PE), and rebreathing into a paper bag is not always recommended . Elevated carbon dioxide levels have been found to trigger panic attacks, which can further exacerbate hyperventilation.

Implementation: Nursing Actions

• Assess respiratory rate, depth, and ease. Monitor vital signs (including temperature) and skin color. Assessment data can help identify the underlying cause, such as a fever or hypoxia. • Obtain subjective assessment data such as the circumstances leading up to the current situation, current health and recent illnesses or medication use, and current manifestations. Subjective data provide clues to the cause and circumstances of the hyperventilation response. • Reassure the patient that the symptoms do not indicate a heart attack and will resolve when breathing returns to normal. Manifestations of hyperventilation and respiratory alkalosis such as dyspnea, chest tightness or pain, and palpitations can mimic those of a heart attack. • Instruct the patient to maintain eye contact and breathe with you to slow the respiratory rate. These measures help make the patient aware of respirations and provide a sense of support and control. Be aware that some patients are uncomfortable making eye contact for cultural reasons. • Protect the patient from injury. If hyperventilation continues to the point where the patient loses consciousness, respirations will return to normal, as will acid-base balance. • Refer for counseling a patient who has experienced repeated episodes of hyperventilation or who has a chronic anxiety disorder. Counseling can help the patient develop alternative strategies for dealing with anxiety.

Diagnosis

• Breathing Pattern, Ineffective • Anxiety Injury, Risk for.

Clinical Manifestations

• Dizziness • Numbness and tingling around mouth, hands, and feet • Palpitations • Dyspnea • Chest tightness • Anxiety/panic • Tremors • Tetany • Seizures or loss of consciousness

Clinical Therapies

• Monitor vital signs, LOC, and ABGs. • Encourage patient to breathe more slowly; teach breathing and stress reduction techniques. • Administer sedative or anti-anxiety agent as ordered. • Monitor ventilator settings. • Administer oxygen as ordered. • Maintain fluid status.

Expected Outcomes

• Patient experiences no subsequent episodes of hyperventilation. • Patient describes strategies for coping with anxiety in the future. • Family displays ability to contribute to calming patient during times of anxiety. • Patient and/or family participate in support groups that will help the patient cope with an anxiety disorder.