gas exchange

This response addresses your learning objectives regarding gas exchange by drawing solely upon the provided source material.

1. Notice risk factors for impaired gas exchange.

Impaired gas exchange can stem from issues related to ventilation, perfusion, or transport.

Risk Factors Related to Impaired Ventilation (COPD): The primary risk factors for Chronic Obstructive Pulmonary Disease (COPD) are environmental and genetic.

  • Smoking is the number one risk factor for COPD.

  • Other environmental risk factors include dust and chemical exposure, combat exposure, and secondhand smoke exposure.

  • Genetic risk factors include Alpha 1 antitrypsin (AAT) deficiency, which affects the liver and lungs.

  • Chronic reactive airway diseases also tend to have a familial history.

  • The function of the mucociliary apparatus (which traps and removes inhaled particles) can be paralyzed by smoking, leading to failure to remove excess particles and increasing the risk of infection.

Risk Factors Related to Impaired Perfusion (Pulmonary Embolism - PE): A pulmonary embolism (PE) can be caused by vascular wall damage, venous stasis, or hypercoagulability. Risk factors for PE include:

  • Long-term immobility.

  • Plane rides.

  • Being in a cast or an accident.

  • COPD or chronic pulmonary disease.

  • Heart failure.

  • AIB (Atrial Fibrillation).

Risk Factors Related to Impaired Transport (Iron Deficiency Anemia): Iron deficiency anemia results in insufficient delivery of oxygen due to an inadequate number of healthy red blood cells (RBCs). Risk populations and causes include:

  • Inadequate intake of iron (e.g., vegans, who do not eat iron-rich meats).

  • Women with excessive menstrual bleeding.

  • Pregnant women (the baby may deplete iron stores).

  • The elderly.

  • Children weaned from breast milk to cow's milk.

  • Teens that are growing quickly.

  • Persons with chronic slow GI bleeding.

  • Disorders leading to malabsorption.

  • Trauma or surgery resulting in significant blood loss.

  • Cancers or treatments for cancers.

2. Recognize when an individual has compromised gas exchange.

Compromised gas exchange manifests differently depending on the underlying pathology (COPD, PE, or anemia).

Condition

Clinical Manifestations

Chronic Bronchitis (Inhibits air in)

Productive, mucousy cough, cyanosis (blue or blue around the mouth, hence "blue bloater"), shortness of breath, use of accessory muscles to breathe, rhonchi or wheezing, peripheral edema, elevated hemoglobin, pulmonary hypertension, digital clubbing, and decreased O2 with normal or increased CO2 on ABGs.

Emphysema (Inhibits air out)

Barrel-shaped chest (hallmark sign), dyspnea on exertion, prolonged expirations, often thin appearance, decreased breath sounds, uses accessory muscles, minimal cyanosis typically, purse-lipped breathing, and may speak in short, jerky sentences.

Pulmonary Embolism (PE)

Dyspnea (often the first manifestation), chest pain, tachycardia, air hunger, a feeling of impending doom, and sometimes blood-tinged sputum with a productive cough.

Iron Deficiency Anemia (Impaired Transport)

General weakness and fatigue (considered the biggest symptom), shortness of breath, particularly on exertion, and PICA cravings (craving non-nutrition substances).

3. Provide appropriate nursing and collaborative interventions for optimizing gas exchange.

Interventions vary based on the cause of impaired gas exchange:

Pulmonary Embolism Interventions: A pulmonary embolism is typically considered a medical emergency. Treatments include:

  • Clot busters (thrombolytics).

  • Surgery for surgical removal.

  • Placing a mesh net to catch clots if other interventions are not feasible.

Chronic Bronchitis (COPD) Intervention Caution:

  • For individuals with chronic bronchitis who are in the stage where their respiratory drive is low O2 driven (instead of CO2 driven), you cannot give them a lot of oxygen (e.g., do not put them on 3 liters of O2). Providing too much oxygen can decrease their respiratory drive, causing them to stop breathing because their body senses sufficient oxygen.

4. Discuss the role of hemoglobin in transport of oxygen throughout the body.

Hemoglobin is a protein located on the red blood cells (RBCs).

  1. Oxygen Binding: Oxygen combines loosely with the heme portion of hemoglobin to form oxyhemoglobin. The heme portion consists of iron and a protein called porphyrin.

  2. Oxygen Transport: The most important function of hemoglobin is to combine with oxygen in the lungs and subsequently release that oxygen to the peripheral tissues. The RBCs carry the oxygen to the vital parts and organs of the body.

  3. Carbon Dioxide Transport: After releasing oxygen, hemoglobin circles back around to collect carbon dioxide from the tissues and carries it to the lungs to be excreted upon exhale.

  4. Oxygen Measurement: The percentage of hemoglobin saturated with oxygen is what is measured when a pulse oximeter is taken.

The ability of hemoglobin to function properly is highly dependent on the availability of iron. A deficiency in iron results in a lack of hemoglobin in each RBC, meaning the red blood cell is not working at its full capacity to carry oxygen.

5. Identify signs of impaired perfusion caused by a pulmonary embolism.

A pulmonary embolism (PE) is an occlusion that results in impaired perfusion. Since the clot blocks the ability to perfuse oxygenated blood, the manifestations are typically acute and include:

  • Dyspnea (usually the first manifestation)

  • Chest pain

  • Tachycardia

  • Air hunger

  • A feeling of impending doom

  • Possible blood-tinged sputum with a productive cough

6. Discuss the physiologic processes of COPD that lead to impaired ventilation.

Chronic Obstructive Pulmonary Disease (COPD) is characterized by increased resistance to airflow, which impairs ventilation. COPD encompasses conditions like chronic bronchitis and emphysema.

Chronic Bronchitis (Inhibits Inspiration):

  • Chronic inhalation of irritants leads to the hypersecretion of mucus in both large and small airways.

  • This excessive mucus secretion results in an obstruction to the inspiratory airway, preventing optimal oxygenation. The patient cannot get air in.

  • This causes severe ventilation imbalances (VQ imbalances) and a decrease in arterial oxygenation.

  • Due to chronic high CO2 levels, chemoceptors become insensitive, causing the respiratory drive to shift from being CO2 driven to being low O2 driven.

Emphysema (Inhibits Expiration):

  • Recurrent inflammation releases proteolytic enzymes, leading to the destruction of elastic fibers.

  • This destruction results in the loss of elastic recoil in the lungs.

  • Air spaces distal to the terminal bronchioles suffer irreversible enlargement.

  • The destruction of alveolar walls creates less surface area for gas exchange.

  • The loss of elasticity causes the alveoli to become like overdistended balloons that cannot recoil, leading to the obstruction of expiratory airflow (difficulty getting air out) and retention of air/CO2.

7. Describe pulmonary embolus and impaired gas exchange.

A pulmonary embolus (PE) is defined as an occlusion of a portion of the pulmonary arterial bed by a thrombus, embolus, tissue fragment, lipids, or an air bubble.

Impaired Gas Exchange:

  • PE results specifically in impaired perfusion.

  • Pathophysiology: A thrombus (clot) in the peripheral blood flow breaks up and becomes an embolus. This embolus travels to the right side of the heart and enters the lung via pulmonary circulation. Once lodged, the PE blocks the body's ability to perfuse oxygenated blood.

8. Describe the acute clinical manifestations of compromised gas exchange.

Acute clinical manifestations can refer to immediate signs of respiratory failure or obstruction:

Signs related to Pulmonary Embolism (an acute emergency):

  • Dyspnea (shortness of breath)

  • Chest pain

  • Tachycardia

  • Air hunger

  • A feeling of impending doom

Signs related to severe oxygen deprivation/respiratory distress (seen in COPD exacerbation):

  • Shortness of breath (dyspnea)

  • Cyanosis (the person is blue, or blue around the mouth)

  • Use of accessory muscles to breathe

  • Low O2 saturation on pulse oximetry