Respiratory Flashcards
What is dead space? And what is its V/Q?
Ventilation without perfusion. Infinity
What is shunt? What is its V/Q?
Perfusion without ventilation.
Zero.
What is V/Q mismatch?
Areas of the lung has different V/Q ratios due to different levels of perfusion and ventilation
Which lobes of the lungs has higher perfusion? How does this affect V/Q?
Lower lobes, therefore they have a lower V/Q
Do areas of high V/Q have high or low levels of oxygenation?
High, as the ventilation is able to saturate the blood
Do areas of low V/Q have high or low levels of oxygenation?
Low, because ventilation is unable to saturate the blood
What does V/Q mismatch cause?
Hypoxemia
How does V/Q mismatch cause hypoxemia?
Areas with increased perfusion, and therefore a low V/Q, will have low oxygen saturation as not enough oxygen through ventilation is present to saturate the blood.
Areas with decreased perfusion, and therefore a high V/Q, will have high oxygen saturation as there is enough oxygen present to saturate the lungs.
As there are more blood cells present with low oxygen, the blood overall will have low oxygen saturation
Causes of V/Q mismatch?
Pneumonia
COPD
Fibrosis
Asthma
Pulmonary embolism
Pulmonary hypertension
When does the oxygen-haemoglobin dissociation curve shift to the right?
In areas requiring more oxygen as haemoglobin more readily releases oxygen when the curve is shifted to the right
High pH, high temp, high PaCO2, high DPG
When does the oxygen-haemoglobin dissociation curve shift to the left?
At areas not requiring oxygen, as haemoglobin more readily holds onto oxygen when the curve is shifted to the left
High pH, low temp, low PaCO2, Low DPG
What is asthma?
A chronic inflammatory disorder of the airways causing inflammation, bronchial hyperresponsiveness and airway narrowing (bronchoconstriction)
What is asthma characterised by?
Inflammation, bronchoconstriction and mucous production
What are the clinical indicators of asthma?
Respiratory compromise
- Decreased ability to speak
- Increased work of breathing
- Tracheal tug
- Cyanosis
- Diaphoresis
- Altered level of consciousness
- Silent chest
- Hypotension
- Bradycardia
What is the pathophysiology of asthma?
- Exposure to trigger (e.g. cigarette smoke or cold air)
- Release of inflammatory mediators (e.g. histamines, interleukins, prostaglandins)
- Bronchial smooth muscle spasm and contraction mediated by acetylcholine, airway oedema, production of thick mucous, airway hyperresponsiveness, thickening of airway walls leading to airway remodelling
- Results in obstruction of the airways, limitation of airflow, air trapping respiratory acidosis, hypoxemia
What are some asthma complications?
- Respiratory failure (hypoxemia or hypercapnia) due to airflow limitation
- Status asthmaticus - acute severe and prolonged asthma attack lasting for 24 hours or more without improvement
How do you manage acute asthma?
- Correct significant hypoxemia with oxygen therapy
- Reverse airflow obstructions through reliever and preventer medications
- Plan to prevent further events through patient education
What should the patient be educated on when aiming to prevent future asthma events?
- The nature of asthma
- Definition of inflammation and bronchoconstriction
- Purpose and action of each medication
- Identification of triggers and how to avoid them
- Proper inhalation techniques
- How to perform peak flow monitoring
- How to implement an action plan
- When and how to seek assistance
What is pneumonia?
An acute infection of the lower respiratory tract caused by bacteria, viruses, fungi, protozoa or parasites
What are 4 different types of pneumonia?
- Community-acquired pneumonia
- Medical care-associated
- Aspiration pneumonia
- Opportunistic pneumonia
What is the pathophysiology of pneumonia?
- Inflammatory response - attraction of neutrophils, release of inflammatory mediators, accumulation of fibrinous exudates, red blood cells and bacteria
- Alveoli fill with fluid and debris (consolidation), and increased production of mucous (airway obstruction)
- These lead to decreased gas exchange
- Resolution of infection - macrophages in alveoli ingest and remove debris, normal lung tissue is restored, gas exchange returns to normal
What is COPD? What are the two diseases that come under COPD?
Progressive chronic disease characterised by irreversible obstruction of the airways.
1. Chronic bronchitis
2. Emphysema
What are some signs and symptoms of COPD?
- Shortness of breath
- Wheezing
- Chest tightness
- Ongoing chronic cough
- Difficulty with routine activities
- Fatigue
- Weight loss
- Muscle loss