A pulmonary function test visualization that plots airflow rate (L/s) against lung volume (L) during forced expiration and inspiration, forming a characteristic loop shape. The expiratory limb rises sharply to Peak Expiratory Flow (PEF) then declines, while the inspiratory limb forms a more symmetric curve below the x-axis. This plot is essential for diagnosing obstructive and restrictive lung diseases by comparing measured loops against predicted normal values.
# anyplot.ai
# spirometry-flow-volume: Spirometry Flow-Volume Loop
# Library: makie 0.22.10 | Julia 1.11.9
# Quality: 90/100 | Created: 2026-06-17
using CairoMakie
using Colors
using Random
Random.seed!(42)
# --- Theme tokens -----------------------------------------------------------
const THEME = get(ENV, "ANYPLOT_THEME", "light")
const PAGE_BG = THEME == "light" ? colorant"#FAF8F1" : colorant"#1A1A17"
const ELEVATED_BG = THEME == "light" ? colorant"#FFFDF6" : colorant"#242420"
const INK = THEME == "light" ? colorant"#1A1A17" : colorant"#F0EFE8"
const INK_SOFT = THEME == "light" ? colorant"#4A4A44" : colorant"#B8B7B0"
const INK_MUTED = THEME == "light" ? colorant"#6B6A63" : colorant"#A8A79F"
const BRAND = colorant"#009E73" # Imprint palette position 1 — measured loop
const REFERENCE = INK_MUTED # Imprint muted anchor — predicted normal overlay
# --- Data: forced expiratory + inspiratory flow-volume loops ----------------
# Volume axis runs 0 (full inflation, TLC) -> FVC (full exhalation, RV).
# Expiratory limb rises sharply to PEF then declines toward zero at FVC;
# inspiratory limb is a symmetric U below the zero-flow line.
n = 160
# Measured loop (mild obstructive pattern: slightly scooped expiratory decline)
fvc_meas = 4.8
pef_meas = 9.6
v_pef_meas = 0.45
pif_meas = 5.4
v_exp_meas = collect(range(0, fvc_meas; length = n))
flow_exp_meas = [v <= v_pef_meas ?
pef_meas * sqrt(v / v_pef_meas) :
pef_meas * ((fvc_meas - v) / (fvc_meas - v_pef_meas))^1.25
for v in v_exp_meas]
v_insp_meas = collect(range(fvc_meas, 0; length = n))
flow_insp_meas = [-pif_meas * sqrt(max(0.0, 1 - ((v - fvc_meas / 2) / (fvc_meas / 2))^2))
for v in v_insp_meas]
volume_meas = vcat(v_exp_meas, v_insp_meas)
flow_meas = vcat(flow_exp_meas, flow_insp_meas)
# Predicted normal loop (reference overlay — larger, near-linear decline)
fvc_pred = 5.3
pef_pred = 10.6
v_pef_pred = 0.5
pif_pred = 6.2
v_exp_pred = collect(range(0, fvc_pred; length = n))
flow_exp_pred = [v <= v_pef_pred ?
pef_pred * sqrt(v / v_pef_pred) :
pef_pred * ((fvc_pred - v) / (fvc_pred - v_pef_pred))
for v in v_exp_pred]
v_insp_pred = collect(range(fvc_pred, 0; length = n))
flow_insp_pred = [-pif_pred * sqrt(max(0.0, 1 - ((v - fvc_pred / 2) / (fvc_pred / 2))^2))
for v in v_insp_pred]
volume_pred = vcat(v_exp_pred, v_insp_pred)
flow_pred = vcat(flow_exp_pred, flow_insp_pred)
# --- Plot -------------------------------------------------------------------
fig = Figure(
size = (1600, 900),
fontsize = 14,
backgroundcolor = PAGE_BG,
)
ax = Axis(
fig[1, 1];
title = "spirometry-flow-volume · julia · makie · anyplot.ai",
titlesize = 22,
titlecolor = INK,
xlabel = "Volume (L)",
ylabel = "Flow (L/s)",
xlabelsize = 16,
ylabelsize = 16,
xlabelcolor = INK,
ylabelcolor = INK,
xticklabelsize = 14,
yticklabelsize = 14,
xticklabelcolor = INK_SOFT,
yticklabelcolor = INK_SOFT,
xtickcolor = INK_SOFT,
ytickcolor = INK_SOFT,
backgroundcolor = PAGE_BG,
topspinevisible = false,
rightspinevisible = false,
leftspinecolor = INK_SOFT,
bottomspinecolor = INK_SOFT,
xgridcolor = RGBAf(INK.r, INK.g, INK.b, 0.12),
ygridcolor = RGBAf(INK.r, INK.g, INK.b, 0.12),
xminorgridvisible = false,
yminorgridvisible = false,
)
xlims!(ax, -0.35, 5.85)
ylims!(ax, -7.8, 12.2)
# Zero-flow reference line separating expiration (above) from inspiration (below)
hlines!(ax, 0; color = RGBAf(INK.r, INK.g, INK.b, 0.35), linewidth = 1.2)
# Predicted normal loop (dashed reference)
lines!(ax, volume_pred, flow_pred;
color = REFERENCE, linewidth = 2.5, linestyle = :dash, label = "Predicted normal")
# Measured loop (solid brand green)
lines!(ax, volume_meas, flow_meas;
color = BRAND, linewidth = 3.2, label = "Measured")
# Peak Expiratory Flow marker
scatter!(ax, [v_pef_meas], [pef_meas];
color = BRAND, markersize = 15, strokecolor = PAGE_BG, strokewidth = 2,
label = "PEF")
text!(ax, v_pef_meas + 0.18, pef_meas;
text = "PEF", color = INK, fontsize = 15, align = (:left, :center))
# Limb annotations
text!(ax, 2.15, 7.4; text = "Expiratory limb", color = INK_MUTED,
fontsize = 14, font = :italic, align = (:center, :bottom))
text!(ax, 2.5, -6.9; text = "Inspiratory limb", color = INK_MUTED,
fontsize = 14, font = :italic, align = (:center, :top))
# Clinical values box (upper-right empty region)
poly!(ax, Point2f[(3.55, 6.4), (5.7, 6.4), (5.7, 11.6), (3.55, 11.6)];
color = ELEVATED_BG, strokecolor = INK_SOFT, strokewidth = 1)
text!(ax, 3.72, 11.0; text = "Spirometry values", color = INK,
fontsize = 16, font = :bold, align = (:left, :center))
text!(ax, 3.72, 9.7; text = "FVC\nFEV1\nFEV1/FVC\nPEF",
color = INK_SOFT, fontsize = 15, align = (:left, :top))
text!(ax, 5.62, 9.7; text = "4.80 L\n3.88 L\n81%\n9.6 L/s",
color = INK, fontsize = 15, align = (:right, :top))
axislegend(ax; position = :lt, framecolor = INK_SOFT, framevisible = true,
backgroundcolor = ELEVATED_BG, labelcolor = INK, labelsize = 14,
padding = (12, 12, 10, 10))
# --- Save -------------------------------------------------------------------
save("plot-$(THEME).png", fig; px_per_unit = 2)
Part of Spirometry Flow-Volume Loop on anyplot.ai.