Summary : This figure presents eight typical flow–volume loop configurations, each illustrating a different pattern of pulmonary function abnormality, including normal, obstructive, restrictive, and mixed disorders. flow–volume loop plots: # Title & Axes : • Figure title: "Examples of typical flow–volume loop configurations for a) normal, b) mild–moderate obstruction, c) severe obstruction, d) variable extrathoracic obstruction, e) fixed large/central airway obstruction, f) unilateral mainstem bronchial obstruction, g) restriction and h) mixed disorder." • X-axis: "Volume (L)" with tick labels ranging from 0 to 6 (varies by panel). • Y-axis: "Flow (L·s⁻¹)" with tick labels ranging from -10 to 10 (varies by panel). # Panels & Data Points : • Panel a) Normal: Loop with peak expiratory flow near 10 L·s⁻¹, volume up to ~6 L, smooth descending limb. • Panel b) Mild–moderate obstruction: Lower peak flow (~8 L·s⁻¹), volume up to ~4 L, scooped-out descending limb. • Panel c) Severe obstruction: Peak flow ~6 L·s⁻¹, volume up to ~2.5 L, pronounced scooping and reduced flow. • Panel d) Variable extrathoracic obstruction: Peak flow ~6 L·s⁻¹, volume up to ~4 L, plateau in inspiratory limb. • Panel e) Fixed large/central airway obstruction: Loops with both inspiratory and expiratory plateaus, volume up to ~4 L, flow range -8 to 8 L·s⁻¹. • Panel f) Unilateral mainstem bronchial obstruction: Peak flow ~3 L·s⁻¹, volume up to ~2 L, irregular loop shape. • Panel g) Restriction: Peak flow ~6 L·s⁻¹, volume up to ~2 L, steep and narrow loop. • Panel h) Mixed disorder: Peak flow ~4 L·s⁻¹, volume up to ~2 L, combination of scooping and restriction features. # Design Encodings : • Each panel shows a single blue line representing the flow–volume loop. • Axes are consistent in style, with horizontal and vertical grid lines. • No additional colour or marker encodings. # Distribution & Trends : • Normal loop (a) is tall and broad, with a rapid rise and gradual fall. • Obstructive loops (b, c) show reduced peak flow and scooped-out descending limbs. • Restrictive loop (g) is narrow and steep, with reduced volume. • Fixed obstruction (e) shows plateaus in both inspiratory and expiratory limbs. • Mixed disorder (h) combines features of obstruction and restriction. # Analysis : • The figure visually distinguishes between normal, obstructive, restrictive, and mixed pulmonary function patterns. • Obstructive patterns are characterised by reduced peak flow and scooping; restrictive patterns by reduced volume and steep loops. • Fixed and variable obstructions show plateaus, while mixed disorders combine features. • These loop shapes are diagnostic for different types of airway and lung pathology.

A multi-panel clinical graphic illustrating the physical and diagnostic findings of Hoover's sign in a patient with airway obstruction. Panels A and B contain clinical photographs of a male patient's torso in a lateral recumbent position. Panel A (Inspiration) demonstrates a paradoxical inward retraction of the lower rib cage and intercostal spaces, a classic physical sign of diaphragmatic flattening often seen in severe COPD or emphysema. Panel B (Expiration) shows the relative expansion or outward movement of the same region. Panel C provides a spirometry data table showing an obstructive pattern: a reduced FEV1/FVC ratio (49%) and low FEF25-75% (31% of predicted). Panel D includes a flow-volume loop demonstrating characteristic expiratory flow limitation and a bar chart of lung volumes. The lung volume chart highlights significant hyperinflation and gas trapping, characterized by an elevated Residual Volume (RV) and Total Lung Capacity (TLC) compared to reference values. This composite image serves to correlate physical examination findings of abnormal chest wall dynamics with quantitative pulmonary function testing in obstructive lung disease.

A multi-panel figure illustrating diagnostic findings in a patient with pulmonary and cardiovascular pathology. (a) A flow-volume loop (spirometry) showing a characteristic downward convex (scooped) expiratory limb indicative of obstructive lung disease, comparing pre-bronchodilator (black) and post-bronchodilator (green) states. (b) Axial contrast-enhanced chest CT at the level of the pulmonary arteries showing no acute thromboembolism. (c) Three-dimensional CT reconstruction of the pulmonary vasculature, with pulmonary arteries color-coded in red and pulmonary veins in blue; no pulmonary arteriovenous malformations or fistulas are identified. (d, e) Nuclear medicine ventilation-perfusion (V/Q) scintigraphy scans; the images demonstrate a V/Q mismatch without focal defects, suggesting a right-to-left shunt. Collectively, these images are used to evaluate platypnea-orthodeoxia syndrome (POS), focusing on identifying potential anatomical causes such as shunts or obstructive impairment.

This composite educational graphic details lung mechanical ventilation reliability and tissue strain analysis using digital volume correlation (DVC). The left panel displays a Pressure-Volume (P-V) curve plot, showing the relationship between Pressure (cmH2O, x-axis from -5 to 35) and Volume (ml, y-axis from 0 to 5). Four ventilation cycles are overlaid as dashed lines, demonstrating sigmoidal hysteretic loops characteristic of respiratory compliance. A solid grey line indicates a consistent compliance range of 0.076–0.077. The right panel consists of two vertically stacked DVC strain field images of lung tissue within an intact thorax, labeled with a 200 µm scale bar. The top image shows the unfiltered strain field, while the bottom image shows the same field after Paganin filtering. The filtered version displays improved contrast between tissue and air by reducing noise within tissue boundaries. Both images include a grayscale color bar indicating 'Maximum Normal Strain (%)' ranging from 0 to 5. This figure illustrates the application of biomedical engineering principles to visualize local lung tissue deformation and characterize pulmonary mechanics during mechanical loading.

This clinical photograph illustrates a research setup for measuring static respiratory compliance during head-out-of-water immersion. A male subject is shown immersed in water up to the level of the sternal notch, a condition that physiologically alters respiratory mechanics due to hydrostatic pressure on the chest wall. The subject is wearing a nose clip to ensure a closed respiratory system, breathing exclusively through a mouthpiece. The mouthpiece is integrated with a pressure sensor and connected via tubing to a calibrated syringe (partially visible) used to manipulate lung volumes. In the background, a computer monitor displays real-time physiological data and waveforms, likely recording the relationship between pressure and volume changes. This experimental design is used in sports medicine and pulmonary physiology to study the effects of immersion on the respiratory system, specifically evaluating parameters like tidal volume, expiratory reserve volume, and overall respiratory system compliance (Crs).

This physiological trace diagram displays multiple respiratory and gas exchange parameters recorded over approximately two minutes and forty seconds during an experimental study on inspiratory resistance. The figure is organized into six vertically stacked panels: inspiratory pressure (cmH2O), respiratory bellows (arbitrary units), carbon dioxide (%), oxygen (%), breathing rate (BPM), and breathing depth (au). Five vertical gray bars indicate periods where an external inspiratory resistance of 55 cmH2O was applied. During these resistance periods, the 'Inspiratory Pressure' trace shows significant negative deflections, reaching approximately -15 cmH2O, reflecting increased inspiratory effort. The 'Carbon Dioxide' trace reveals rhythmic oscillations corresponding to the respiratory cycle; asterisks (*) are placed above the peaks immediately following each gray period to highlight an increase in end-tidal carbon dioxide (PETCO2). The 'Oxygen' trace shows inverse oscillations to CO2. The bottom panels utilize step-graphs to track dynamic changes in breathing frequency and volume (depth). This visualization demonstrates the acute physiological and compensatory responses of the respiratory system to sudden, external mechanical loads.

This physiological data plot illustrates respiratory mechanics across four stacked time-series graphs (0-60 seconds) during normal breathing. The top plot displays 'Pressure at venturi throat [cmH2O]', showing cyclic negative pressure spikes corresponding to inspiratory effort. The second plot shows 'Flow [L/s]', with positive deflections representing inspiration and negative deflections representing expiration. The third plot displays 'Tidal Volume [L]', depicting the cumulative volume inhaled and exhaled per breath, peaking at approximately 0.8L. The bottom plot compares 'Circumference of Chest and Abdomen [mm]', featuring a blue line for chest expansion (ranging 830-840mm) and a red line for abdominal expansion (ranging 740-750mm). Dashed vertical lines mark the start of each inspiration index (InspInd), synchronizing the mechanical pressure drops and flow changes with physical chest/abdomen movement. This visualization is used in critical care and respiratory physiology to evaluate breathing patterns, work of breathing, and thoracoabdominal synchrony.