Ventilation & perfusion

What is the significance of V/Q matching in the lungs?

Efficient and adequate matching between ventilation and perfusion ensures optimal oxygenation of blood and effective removal of CO2.

What conditions can lead to increased V/Q mismatch?

Poor ventilation causes blood to shunt toward better ventilated areas, while poor perfusion results in dead space due to adequate ventilation without blood flow.

What factors influence ventilation in the lungs?

Airway resistance and pleural pressure gradient influence ventilation.

How does body position affect ventilation?

Upright standing maximizes lung volumes and capacities and optimizes ventilation.

What is functional residual capacity (FRC)?

The amount of air remaining in the lungs after passive exhalation; FRC is greater when standing compared to sitting.

How does the positioning of alveoli in the lungs affect ventilation?

Alveoli at the apex are stretched and have higher negative intrapleural pressure, whereas the bases are squashed and have lower negative intrapleural pressure.

What is a common consequence of prolonged poor positioning in ventilated patients?

It can compress the bottom lung, leading to poor ventilation, especially in moderate to severely obese individuals.

How does deep breathing exercise help patients?

It encourages basal ventilation, increases diffusion, improves lung compliance, and enhances ventilation distribution through collateral pathways.

What factors affect perfusion in the lungs?

Perfusion is affected by gravity and lung volume, with more blood volume directed towards the bases of the lungs.

How does hypoxic vasoconstriction limit V/Q mismatch?

It constricts arterioles to limit 'wasted perfusion' when ventilation is reduced.

What is the significance of arterial blood gas analysis (ABG)?

ABG is used to assess patients with sudden unexplained dyspnea, cyanosis, and other abnormalities by measuring pH, PaCO2, PaO2, and HCO3 levels.

What indicates acidosis in an ABG analysis?

A decrease in pH suggests acidosis; it can lead to depression of the CNS.

What characterizes metabolic alkalosis based on ABG results?

An increase in pH with elevated bicarbonate levels as a result of excessive loss of H+ ions.

What oxygenation levels indicate mild hypoxemia?

A PaO2 between 70-80 mmHg or SaO2 below 90%.

What are the signs of CO2 retention?

Signs may include lethargy, confusion, and other cognitive changes depending on the severity.

What should you do after interpreting an ABG?

Assess clinical data and previous ABG results, then address any primary respiratory or metabolic issues.

What does a decrease in FEV1/FVC ratio indicate?

It suggests obstructive lung disease.

How do inhaled corticosteroids function?

They suppress inflammation that triggers bronchospasm, edema, and mucus hypersecretion.

What are the implications for physiotherapy for patients on inhaled corticosteroids?

Encourage rinsing the mouth to prevent candidiasis and monitor for osteoporosis in high-dose users.

What is the role of pulmonary rehabilitation?

To improve well-being in chronic respiratory diseases by enhancing function, reducing symptoms, and providing education.