First 8 h{pk.first8.toLocaleString()} mL LR · {pk.rateFirst8} mL/hr
Next 16 h{pk.next16.toLocaleString()} mL LR · {pk.rateNext16} mL/hr
{tbsa < 20 && (
{'<'}20% TBSA: oral hydration usually sufficient.
)}
{tbsa >= 20 && (
Major burn — start LR resuscitation, titrate to UOP 0.5 mL/kg/h.
)}
) : (
Set patient weight in roster to compute Parkland.
)}
);
}
function nowHHMM() {
const d = new Date();
return String(d.getHours()).padStart(2,'0') + String(d.getMinutes()).padStart(2,'0');
}
/* Shoelace formula — polygon area in viewBox² (kept as a fallback) */
function polygonArea(points) {
if (!points || points.length < 3) return 0;
let area = 0;
for (let i = 0, j = points.length - 1; i < points.length; j = i++) {
area += (points[j].x + points[i].x) * (points[j].y - points[i].y);
}
return Math.abs(area / 2);
}
/* Pixel-accurate TBSA for freeform outlines.
Each anatomical view (front / back) represents 50% of total body surface,
so a freeform patch's contribution is:
(patch ∩ silhouette pixels) / (silhouette pixels) × 50%
We rasterize the silhouette once and clip every patch to it so polygons
drawn outside the body don't inflate the percentage. */
let __silhouettePixelCount = null;
function getSilhouettePixelCount() {
if (__silhouettePixelCount != null) return __silhouettePixelCount;
try {
const c = document.createElement('canvas');
c.width = BODY_W; c.height = BODY_H;
const ctx = c.getContext('2d');
if (!ctx || typeof Path2D === 'undefined') return null;
ctx.fillStyle = '#000';
ctx.fill(new Path2D(SILHOUETTE_PATH));
const data = ctx.getImageData(0, 0, BODY_W, BODY_H).data;
let n = 0;
for (let i = 3; i < data.length; i += 4) if (data[i] > 0) n++;
__silhouettePixelCount = n;
return n;
} catch (e) { return null; }
}
const __burnPatchPctCache = new Map();
function patchTBSAPercent(points) {
if (!points || points.length < 3) return 0;
// Use a stable key based on rounded coords to avoid floating-point churn
const key = points.map(p => `${Math.round(p.x*4)},${Math.round(p.y*4)}`).join(';');
if (__burnPatchPctCache.has(key)) return __burnPatchPctCache.get(key);
const bodyPx = getSilhouettePixelCount();
let pct;
if (bodyPx && typeof Path2D !== 'undefined') {
try {
const c = document.createElement('canvas');
c.width = BODY_W; c.height = BODY_H;
const ctx = c.getContext('2d');
ctx.save();
ctx.clip(new Path2D(SILHOUETTE_PATH)); // restrict to silhouette
ctx.beginPath();
ctx.moveTo(points[0].x, points[0].y);
for (let i = 1; i < points.length; i++) ctx.lineTo(points[i].x, points[i].y);
ctx.closePath();
ctx.fillStyle = '#000';
ctx.fill();
ctx.restore();
const data = ctx.getImageData(0, 0, BODY_W, BODY_H).data;
let patchPx = 0;
for (let i = 3; i < data.length; i += 4) if (data[i] > 0) patchPx++;
// Each view is 50% of total body surface (front + back = 100%)
pct = (patchPx / bodyPx) * 50;
} catch (e) {
// Fall through to shoelace approximation
pct = (polygonArea(points) / (BODY_W * BODY_H * 0.40 * 2)) * 100;
}
} else {
pct = (polygonArea(points) / (BODY_W * BODY_H * 0.40 * 2)) * 100;
}
__burnPatchPctCache.set(key, pct);
return pct;
}
/* Sum the TBSA % values of the selected Rule-of-9 regions plus any
freeform outline patches (measured by silhouette-clipped raster area). */
function estimateBurnTBSA(injuries, burnedRegions) {
let total = 0;
for (const key of (burnedRegions || [])) {
const r = BURN_REGIONS[key];
if (r) total += r.tbsa;
}
const patches = (injuries || []).filter(i => i.type === 'burn' && i.points && i.points.length >= 3);
for (const p of patches) total += patchTBSAPercent(p.points);
return Math.min(100, Math.max(0, total));
}
/* Parkland formula: 4 mL × kg × %TBSA in 24h, half over first 8h, half over next 16h. */
function parkland(tbsaPct, weightKg) {
const w = Number(weightKg) || 0;
const t = Number(tbsaPct) || 0;
const total = 4 * w * t;
const first8 = total / 2;
const next16 = total / 2;
return {
total: Math.round(total),
first8: Math.round(first8),
next16: Math.round(next16),
rateFirst8: Math.round(first8 / 8),
rateNext16: Math.round(next16 / 16),
};
}
Object.assign(window, { BodyDiagram, nowHHMM, estimateBurnTBSA, parkland });