WEEK 3 ventilation Flashcards
Broad concepts in ventilation (16 cards)
What is respiration?
The process of gas exchange between atmospheric air and the blood-and between the blood and the cells of the body -to provide oxygenation and remove carbon dioxide from the cells.
What is ventilation?
Ventilation is the movement of air into and out of the lungs - to make available for gas exchange. Air, like other gases, flows from a region with higher pressure to a region with lower pressure. Muscular breathing movements and recoil of elastic tissues create the changes in pressure that result in ventilation.
What is inspiration?
Inspiration (inhalation) is the process of taking air into the lungs. It is the active phase of ventilation where the diaphragm contracts and the thoracic cavity increases in volume. This decreases the intra-alveolar pressure so that air flows into the lungs.
What is Expiration?
Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle. During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intra-alveolar pressure. Expiration pushes air out of the lungs. This process normally takes twice as long as inspiration.
In order to work effectively, the respiratory system requires:
- A patent airway system to transport air
- An effective alveolar system to allow diffusion of gases into and out of the blood.
- An effective cardiovascular system to transport blood, deliver O2 + nutrients and remove waste.
Define Hypoventilation
This occurs when ventilation is inadequate to remove carbon dioxide (CO2) produced by the body’s metabolism. It can lead to an increase in blood CO2 levels (hypercapnia), resulting in symptoms such as drowsiness, confusion, and, in severe cases, respiratory failure
Define Hyperventilation.
Hyperventilation is characterized by excessive and rapid breathing, which causes a decrease in blood CO2 levels (hypocapnia). Symptoms may include dizziness, tingling sensations, and muscle cramps.
What are Obstructive Ventilation Problems?
These issues involve physical blockages or restrictions in the airways that impede the flow of air. Conditions like asthma, chronic obstructive pulmonary disease (COPD), and sleep apnea are examples of obstructive ventilation problems.
What are Restrictive Ventilation Problems?
Restrictive lung diseases cause a reduction in lung expansion, making it difficult for the lungs to expand fully during inhalation. Conditions like interstitial lung disease and chest wall deformities can lead to restrictive ventilation problems.
What is Ventilation-Perfusion Mismatch?
This occurs when there is an imbalance between the amount of air reaching the alveoli (ventilation) and the amount of blood perfusing these areas (perfusion). Ventilation-perfusion mismatch can be caused by conditions like pulmonary embolism (perfusion problem), pneumonia or pulmonary oedema (ventilation problem) .
What is Asthma?
Asthma is a chronic respiratory condition characterized by inflammation and constriction of the airways, leading to recurrent episodes of wheezing, breathlessness, coughing, and chest tightness. The pathophysiology of asthma involves complex interactions among various cellular and molecular factors.
What is Chronic Obstructive Pulmonary Disease (COPD)?
Chronic Obstructive Pulmonary Disease (COPD) is a progressive and irreversible respiratory condition characterized by the obstruction of airflow in the lungs. The pathophysiology of COPD primarily involves chronic inflammation and structural changes in the airways and lung tissue.
What is Emphysema?
In COPD, the destruction of lung tissue and loss of elasticity is common. This is known as emphysema.
Emphysema results in the loss of the lung’s ability to recoil and expel air, leading to air trapping and hyperinflation of the lungs.
What are the physiological concepts in oxygen therapy?
The effect of the inspiratory flow rate: The peak inspiratory flow rate (PIFR) in adults is 30 L/min at rest. In the resting adult, the tidal volume is 500 mL and the respiratory rate is 15/min. Therefore, the resting minute volume (500 15) in an adult is about 7.5 L/min.
The effect of the respiratory minute volume: A reservoir bag enables storage of oxygen during the expiratory phase of ventilation, which may then be used for the subsequent inspiratory phase.
Define Oxygen Toxicity
Damage may occur to the lungs, eyes and occasionally the CNS and is thought to be caused by the development of free radicals and toxic lipid peroxides. Adverse oxygen reactions include removal of the hypoxic stimulus to ventilation in patients with COPD and the development of retrolental fibroplasia and pulmonary toxicity (Lorrain Smith effect) in premature infants.
How does pulmonary toxicity in oxygen toxicity occur?
Pulmonary toxicity can occur with > 60% exposure for > 24 hours and may result in lung injury with a non-cardiogenic pulmonary oedema type of picture; if exposure is more prolonged, pulmonary fibrosis may develop. Some patients may develop CNS toxicity, which manifests as neuromuscular irritability and seizures.
