volume restoration

What is tidal volume (VT)?

Air moved in or out during a normal quiet breath.

What is inspiratory reserve volume (IRV)?

Extra air inspired after a normal tidal inspiration.

What is expiratory reserve volume (ERV)?

Extra air exhaled after a normal tidal expiration.

What is residual volume (RV)?

Air remaining after maximal expiration.

What is vital capacity (VC)?

Maximum air exhaled after maximal inspiration; IRV + VT + ERV.

What is inspiratory capacity (IC)?

Maximum air inspired after normal expiration; VT + IRV.

What is functional residual capacity (FRC)?

Air remaining in the lungs after a normal passive expiration; ERV + RV.

What is total lung capacity (TLC)?

Lung volume after maximal inspiration; VC + RV.

What balances at FRC?

Inward elastic recoil of the lungs and outward recoil of the chest wall.

Why is FRC important for gas exchange?

It provides an alveolar gas reservoir between breaths.

What can decreased tidal volume indicate?

Shallow breathing and reduced fresh gas reaching alveoli.

Why can a low VT reduce oxygen transfer?

Less fresh oxygen reaches alveoli for diffusion into blood.

What does reduced vital capacity limit?

Depth of inspiration and maximum exhaled volume.

How can reduced VC impair cough?

It limits inspired volume, expiratory flow and cough effectiveness.

What secretion problem follows an ineffective cough?

Reduced ability to mobilise and clear secretions.

What can reduced FRC indicate?

Generalised reduction in resting lung volume.

What can reduced TLC indicate?

Generalised reduction in maximum lung volume.

What is atelectasis?

Partial or complete collapse of lung tissue, causing loss of aeration.

What happens when shallow breathing reduces alveolar stretch?

Surfactant release may fall and alveoli become less stable.

What is the effect of reduced surfactant?

Higher surface tension and greater tendency for alveoli to collapse.

How does increased surface tension affect compliance?

More pressure is needed to inflate alveoli, reducing compliance.

What is lung compliance?

Change in lung volume per unit change in transpulmonary pressure.

What does decreased lung compliance mean?

Stiffer lungs that require greater pressure to expand.

How can sustained shallow breathing lead to low FRC?

Reduced recruitment and airway/alveolar closure reduce resting lung volume.

How does alveolar collapse affect ventilation distribution?

It redirects ventilation away from poorly aerated or closed units.

Which parts of the respiratory system control breathing?

Cortex, brainstem, spinal cord, peripheral nerves and neuromuscular junctions.

Which structures contribute to chest-wall mechanics?

Respiratory muscles, ribs, other bones and chest-wall compliance.

Which factors contribute to respiratory load?

Airway resistance, lung compliance and chest-wall compliance.

What is mucociliary clearance (MCC)?

Cilia move mucus and trapped material toward larger airways.

Which manoeuvres can move secretions by expiratory airflow?

Coughing, huffing and sneezing.

What determines passive lung inflation ease?

Lung compliance and the pressure distending the lungs.

What posture generally gives the highest FRC?

Standing upright.

Which has a higher FRC: upright sitting or supine?

Upright sitting, in general.

How does going from upright to supine affect FRC?

FRC usually decreases.

How can obesity affect FRC?

Abdominal and thoracic loading commonly reduce FRC.

How can general anaesthesia affect FRC?

It commonly reduces FRC and increases atelectasis risk.

How can abdominal or thoracic surgery reduce FRC?

Pain, altered mechanics and anaesthesia promote shallow breathing and collapse.

Why may neonates have low FRC?

A highly compliant chest wall allows inward lung recoil to reduce volume.

How can acute cervical spinal cord injury reduce lung volumes?

Respiratory muscle impairment reduces inspiratory expansion and cough.

How can pulmonary fibrosis reduce lung volumes?

Stiff lung tissue lowers compliance and restricts expansion.

How can thoracic spine deformity reduce lung volumes?

Restricted chest-wall movement limits lung expansion.

At normal upright FRC, which lung region is more expanded at rest?

Apical (non-dependent) alveoli.

At normal upright FRC, which region typically expands more during tidal inspiration?

Basal (dependent) lung regions.

Why do dependent regions receive more tidal ventilation at normal FRC?

They start on a steeper part of the pressure-volume curve.

At very low lung volumes, why might ventilation shift towards upper regions?

Dependent airway closure and poor compliance can limit basal ventilation.

What is closing volume (CV)?

Volume exhaled from onset of small-airway closure to residual volume.

What is closing capacity (CC)?

Lung volume at the onset of small-airway closure during expiration; CV + RV.

What is the relationship between CC and RV?

CC is above RV because it includes closing volume.

What is the desirable relationship between FRC and CC?

FRC should exceed CC to limit airway closure during quiet breathing.

What happens if CC exceeds FRC?

Some small airways close during normal tidal expiration.

What happens distal to a closed small airway?

Ventilation is reduced or absent until the airway reopens.

How does ageing affect CC?

CC generally increases with age.

How can smoking affect CC?

It can increase CC by promoting small-airway dysfunction and loss of support.

Does healthy ageing generally cause the same FRC change as CC?

No; CC increases more consistently, while FRC changes relatively little.

Why does the supine position raise airway-closure risk?

It lowers FRC toward or below CC.

How can obesity and anaesthesia worsen small-airway closure?

They further lower FRC relative to CC.

Name three common causes of localised lung volume loss.

Lobar/segmental collapse, pleural effusion and rib fractures.

What does a collapsed lobe cause physiologically?

Local reduction in ventilation and oxygen transfer.

What opacity change suggests right upper lobe collapse?

Increased right upper-zone opacity.

What tracheal shift can occur with right upper lobe collapse?

Shift toward the right, the side of volume loss.

What fissure change suggests right upper lobe collapse?

Elevation or displacement of the right horizontal fissure.

What diaphragm change may occur with right upper lobe collapse?

Elevation of the right hemidiaphragm.

What common CXR feature suggests pleural effusion?

Dependent/basal opacity with blunting of the costophrenic angle.

What is the meniscus sign on chest X-ray?

A curved upper border of pleural fluid.

What silhouette can be lost in a left pleural effusion?

Left hemidiaphragm border.

How does pleural effusion reduce ventilation?

Fluid compresses the adjacent lung, reducing expansion and causing atelectasis.

Why is oxygen transfer impaired around a pleural effusion?

Compressed alveoli receive less ventilation.

How does rib fracture pain affect breathing?

It encourages shallow breaths and limits deep inspiration.

How can rib fractures affect chest-wall motion?

Pain or instability reduces local expansion.

What is flail chest?

A chest-wall segment moves abnormally due to multiple rib fractures.

What secondary lung problem may follow rib fractures?

Local atelectasis from reduced expansion.

What is pulmonary contusion?

Bruising of lung tissue after trauma.

How does pulmonary contusion affect lung mechanics?

Oedema and tissue injury reduce compliance and impair gas exchange.

Why can rib fractures impair secretion clearance?

Pain inhibits deep breaths and an effective cough.

How can low FRC impair mucociliary clearance?

Airway closure limits ventilation and effective mucus transport.

How does reduced ability to inhale deeply impair secretion clearance?

It reduces the volume and flow available for an effective cough.

Why does impaired secretion clearance increase infection risk?

Retained secretions favour microbial growth and obstruction.

What are three major consequences of low lung volume?

Impaired oxygen transfer, increased respiratory load and poor secretion clearance.

What symptom may accompany reduced lung volume?

Shortness of breath.

What chest-wall finding may suggest reduced lung volume?

Reduced expansion, either generalised or localised.

What breathing-rate change may occur with reduced lung volume?

Increased respiratory rate (tachypnoea).

What accessory-muscle finding may occur?

Increased accessory respiratory muscle use.

What breath sounds may occur over collapsed lung?

Reduced or absent breath sounds.

What crackles may be heard when small airways reopen?

Fine end-inspiratory crackles.

What X-ray structural sign supports volume loss?

Elevated hemidiaphragm or shift of structures toward the affected side.

What X-ray density change may suggest atelectasis?

Increased opacity in the affected region.

What oxygenation result may reflect reduced lung volumes?

Reduced PaO2 and often reduced SpO2.

Is PaCO2 always elevated with reduced lung volumes?

No; it may be normal or high depending on overall alveolar ventilation.

What cough finding suggests secretion-clearance impairment?

A weak or ineffective cough.

What is relaxed breathing?

Comfortable quiet tidal breathing with reduced unnecessary upper-chest tension.

Does relaxed breathing directly aim to increase lung volume?

No; it aims to reduce excess effort and promote relaxation.

Which airway-clearance approach includes relaxed breathing?

The active cycle of breathing techniques (ACBT).

What are the three broad strategies for restoring lung volume?

Increase inspired volume, increase FRC and re-expand localised loss.

What is the main goal of deep breathing exercises (DBE)?

Increase inspiratory volume and recruit underventilated lung units.

What is another name for thoracic expansion exercises?

Deep breathing exercises (DBE).

What does LBE stand for?

Lateral basal expansion.

What does TEE stand for?

Thoracic expansion exercises.

What does a deep inspiration do to type II alveolar cells?

Alveolar stretch can stimulate surfactant secretion.

How can DBE improve alveolar stability?

Recruitment and surfactant support reduce alveolar collapse tendency.

How can DBE affect oxygen transfer?

More alveoli may ventilate, improving regional gas movement.