Ventilation or Perfusion Imbalance
NOC Outcomes (Nursing Outcomes Classification)
Suggested NOC Labels
* Respiratory Status
* Gas Exchange
NIC Interventions (Nursing Interventions Classification)
Suggested NIC Labels
* Respiratory Monitoring
* Oxygen Therapy
* Airway Management
NANDA Definition: Excess or deficit in oxygenation and/or carbon dioxide elimination at the alveolar-capillary membrane
By the process of diffusion the exchange of oxygen and carbon dioxide occurs in the alveolar-capillary membrane area. The relationship between ventilation (airflow) and perfusion (blood flow) affects the efficiency of the gas exchange. Normally there is a balance between ventilation and perfusion; however, certain conditions can offset this balance, resulting in impaired gas exchange. Altered blood flow from a pulmonary embolus, or decreased cardiac output or shock can cause ventilation without perfusion. Conditions that cause changes or collapse of the alveoli (e.g., atelectasis, pneumonia, pulmonary edema, and adult respiratory distress syndrome [ARDS]) impair ventilation. Other factors affecting gas exchange include high altitudes, hypoventilation, and altered oxygen-carrying capacity of the blood from reduced hemoglobin. Elderly patients have a decrease in pulmonary blood flow and diffusion as well as reduced ventilation in the dependent regions of the lung where perfusion is greatest. Chronic conditions such as chronic obstructive pulmonary disease (COPD) put these patients at greater risk for hypoxia. Other patients at risk for impaired gas exchange include those with a history of smoking or pulmonary problems, obesity, prolonged periods of immobility, and chest or upper abdominal incisions.
* Defining Characteristics: Confusion
* Inability to move secretions
* Related Factors: Altered oxygen supply
* Alveolar-capillary membrane changes
* Altered blood flow
* Altered oxygen-carrying capacity of blood
* Expected Outcomes Patient maintains optimal gas exchange as evidenced by normal arterial blood gases (ABGs) and alert responsive mentation or no further reduction in mental status.
* Assess respirations: note quality, rate, pattern, depth, and breathing effort. Both rapid, shallow breathing patterns and hypoventilation affect gas exchange. Shallow, "sighless" breathing patterns postsurgery (as a result of effect of anesthesia, pain, and immobility) reduce lung volume and decrease ventilation.
* Assess lung sounds, noting areas of decreased ventilation and the presence of adventitious sounds.
* Assess for signs and symptoms of hypoxemia: tachycardia, restlessness, diaphoresis, headache, lethargy, and confusion.
* Assess for signs and symptoms of atelectasis: diminished chest excursion, limited diaphragm excursion, bronchial or tubular breath sounds, rales, tracheal shift to affected side. Collapse of alveoli increases physiological shunting.
* Assess for signs or symptoms of pulmonary infarction: cough, hemoptysis, pleuritic pain, consolidation, pleural effusion, bronchial breathing, pleural friction rub, fever.
* Monitor vital signs. With initial hypoxia and hypercapnia, blood pressure (BP), heart rate, and respiratory rate all rise. As the hypoxia and/or hypercapnia becomes more severe, BP may drop, heart rate tends to continue to be rapid with arrhythmias, and respiratory failure may ensue with the patient unable to maintain the rapid respiratory rate.
* Assess for changes in orientation and behavior. Restlessness is an early sign of hypoxia. Chronic hypoxemia may result in cognitive changes such as memory changes.
* Monitor ABGs and note changes. Increasing PaCO2 and decreasing PaO2 are signs of respiratory failure. As the patient begins to fail, the respiratory rate will decrease and PaCO2 will begin to rise. Some patients, such as those with COPD, have a significant decrease in pulmonary reserves, and any physiological stress may result in acute respiratory failure.
* Use pulse oximetry to monitor oxygen saturation and pulse rate. Pulse oximetry is a useful tool to detect changes in oxygenation. Oxygen saturation should be maintained at 90% or greater. This tool can be especially helpful in the outpatient or rehabilitation setting where patients at risk for desaturation from chronic pulmonary diseases can monitor the effects of exercise or activity on their oxygen saturation levels. Home oxygen therapy can then be prescribed as indicated. Patients should be assessed for the need for oxygen both at rest and with activity. A higher liter flow of oxygen is generally required for activity versus rest (e.g., 2 L at rest, and 4 L with activity). Medicare guidelines for reimbursement for home oxygen require a PaCO2 less than 58 and/or oxygen saturation of 88% or less on room air. Oxygen delivery is then titrated to maintain an oxygen saturation of 90% or greater.
* Assess skin color for development of cyanosis. For cyanosis to be present, 5 g of hemoglobin must desaturate.
* Monitor chest x-ray reports. Chest x-rays may guide the etiological factors of the impaired gas exchange. Keep in mind that radiographic studies of lung water lag behind clinical presentation by 24 hours.
* Monitor effects of position changes on oxygenation (SaO2, ABGs, SVO2, and end-tidal CO2). Putting the most congested lung areas in the dependent position (where perfusion is greatest) potentiates ventilation and perfusion imbalances.
* Assess patient’s ability to cough effectively to clear secretions. Note quantity, color, and consistency of sputum. Retained secretions impair gas exchange.
* Maintain oxygen administration device as ordered, attempting to maintain oxygen saturation at 90% or greater. This provides for adequate oxygenation.
Avoid high concentration of oxygen in patients with COPD. Hypoxia stimulates the drive to breathe in the chronic CO2 retainer patient. When applying oxygen, close monitoring is imperative to prevent unsafe increases in the patient’s PaO2, which could result in apnea.
NOTE: If the patient is allowed to eat, oxygen still must be given to the patient but in a different manner (e.g., changing from mask to a nasal cannula). Eating is an activity and more oxygen will be consumed than when the patient is at rest. Immediately after the meal, the original oxygen delivery system should be returned.
* For patients who should be ambulatory, provide extension tubing or portable oxygen apparatus. These promote activity and facilitate more effective ventilation.
* Position with proper body alignment for optimal respiratory excursion (if tolerated, head of bed at 45 degrees). This promotes lung expansion and improves air exchange.
* Routinely check the patient’s position so that he or she does not slide down in bed. This would cause the abdomen to compress the diaphragm, which would cause respiratory embarrassment.
* Position patient to facilitate ventilation/perfusion matching. Use upright, high-Fowler’s position whenever possible. High-Fowler’s position allows for optimal diaphragm excursion. When patient is positioned on side, the good side should be down (e.g., lung with pulmonary embolus or atelectasis should be up).
* Pace activities and schedule rest periods to prevent fatigue. Even simple activities such as bathing during bed rest can cause fatigue and increase oxygen consumption.
* Change patient’s position every 2 hours. This facilitates secretion movement and drainage.
* Suction as needed. Suction clears secretions if the patient is unable to effectively clear the airway.
* Encourage deep breathing, using incentive spirometer as indicated. This reduces alveolar collapse.
* For postoperative patients, assist with splinting the chest. Splinting optimizes deep breathing and coughing efforts.
* Encourage or assist with ambulation as indicated. This promotes lung expansion, facilitates secretion clearance, and stimulates deep breathing.
* Provide reassurance and allay anxiety:
o Have an agreed-on method for the patient to call for assistance (e.g., call light, bell).
o Stay with the patient during episodes of respiratory distress.
* Anticipate need for intubation and mechanical ventilation if patient is unable to maintain adequate gas exchange. Early intubation and mechanical ventilation are recommended to prevent full decompensation of the patient. Mechanical ventilation provides supportive care to maintain adequate oxygenation and ventilation to the patient. Treatment also needs to focus on the underlying causal factor leading to respiratory failure.
* Administer medications as prescribed. The type depends on the etiological factors of the problem (e.g., antibiotics for pneumonia, bronchodilators for COPD, anticoagulants/thrombolytics for pulmonary embolus, analgesics for thoracic pain).
Education/Continuity of Care
* Explain the need to restrict and pace activities to decrease oxygen consumption during the acute episode.
* Explain the type of oxygen therapy being used and why its maintenance is important. Issues related to home oxygen use, storage, or precautions need to be addressed.
* Teach the patient appropriate deep breathing and coughing techniques. These facilitate adequate air exchange and secretion clearance.
* Assist patient in obtaining home nebulizer, as appropriate, and instruct in its use in collaboration with respiratory therapist.
* Refer to home health services for nursing care or oxygen management as appropriate.