pediatric-ai-scribe-v3/public/js/bedside/burns.js

// ============================================================
// bedside/burns.js
// BURNS — Lund-Browder body parts + Parkland formula.
// ============================================================

import { S } from './shared.js';

// Lund-Browder age-adjusted region percentages. Regions marked "*" change with age.
// Column order: infant, young (1-5), child (5-10), adol (10-15), adult (>15).
var LB = {
  head:      { label: 'Head',                vals: [18, 13, 11, 9, 7],    ageSensitive: true },
  neck:      { label: 'Neck',                vals: [2, 2, 2, 2, 2] },
  ant_trunk: { label: 'Anterior trunk',      vals: [13, 13, 13, 13, 13] },
  post_trunk:{ label: 'Posterior trunk',     vals: [13, 13, 13, 13, 13] },
  r_buttock: { label: 'Right buttock',       vals: [2.5, 2.5, 2.5, 2.5, 2.5] },
  l_buttock: { label: 'Left buttock',        vals: [2.5, 2.5, 2.5, 2.5, 2.5] },
  genital:   { label: 'Genitalia',           vals: [1, 1, 1, 1, 1] },
  r_uparm:   { label: 'R upper arm',         vals: [4, 4, 4, 4, 4] },
  l_uparm:   { label: 'L upper arm',         vals: [4, 4, 4, 4, 4] },
  r_forearm: { label: 'R forearm',           vals: [3, 3, 3, 3, 3] },
  l_forearm: { label: 'L forearm',           vals: [3, 3, 3, 3, 3] },
  r_hand:    { label: 'R hand',              vals: [2.5, 2.5, 2.5, 2.5, 2.5] },
  l_hand:    { label: 'L hand',              vals: [2.5, 2.5, 2.5, 2.5, 2.5] },
  r_thigh:   { label: 'R thigh',             vals: [5.5, 8, 8.5, 9, 9.5],  ageSensitive: true },
  l_thigh:   { label: 'L thigh',             vals: [5.5, 8, 8.5, 9, 9.5],  ageSensitive: true },
  r_leg:     { label: 'R lower leg',         vals: [5, 5.5, 6, 6.5, 7],    ageSensitive: true },
  l_leg:     { label: 'L lower leg',         vals: [5, 5.5, 6, 6.5, 7],    ageSensitive: true },
  r_foot:    { label: 'R foot',              vals: [3.5, 3.5, 3.5, 3.5, 3.5] },
  l_foot:    { label: 'L foot',              vals: [3.5, 3.5, 3.5, 3.5, 3.5] }
};
var AGE_KEYS = ['infant','young','child','adol','adult'];

function ageIdx() { return Math.max(0, AGE_KEYS.indexOf(document.getElementById('burn-age').value)); }

function renderBodyParts() {
  var wrap = document.getElementById('burn-bodyparts-wrapper');
  if (!wrap) return;
  var idx = ageIdx();
  var html = '<div style="background:var(--g50);border-radius:8px;padding:10px 12px;">';
  html += '<div style="font-size:12px;color:var(--g600);margin-bottom:8px;line-height:1.4;">For each involved body region, enter <strong>% of that region burned (2° or deeper)</strong>. Leave 0 if uninvolved. TBSA = sum of (region size × % involvement).</div>';
  html += '<div style="display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:6px;">';
  Object.keys(LB).forEach(function(key) {
    var r = LB[key];
    var max = r.vals[idx];
    var isAgeDep = r.ageSensitive;
    html += '<div style="display:flex;align-items:center;gap:8px;padding:4px 8px;background:white;border-radius:6px;border:1px solid var(--g200);">' +
            '<label style="flex:1;font-size:12px;color:var(--g700);">' + r.label + ' <span style="color:var(--g400);">(' + max + '%' + (isAgeDep ? '<span title="age-adjusted">*</span>' : '') + ')</span></label>' +
            '<input type="number" min="0" max="100" step="5" value="0" data-burn-region="' + key + '" data-burn-max="' + max + '" style="width:68px;padding:3px 6px;border:1px solid var(--g300);border-radius:4px;font-size:12px;text-align:right;"> %' +
            '</div>';
  });
  html += '</div></div>';
  wrap.innerHTML = html;
  updateLive();
}

function resetParts() {
  var inputs = document.querySelectorAll('[data-burn-region]');
  inputs.forEach(function(i) { i.value = 0; });
  document.getElementById('burn-tbsa').value = '';
  updateLive();
}

function computeTbsa() {
  var idx = ageIdx();
  var total = 0;
  Object.keys(LB).forEach(function(key) {
    var el = document.querySelector('[data-burn-region="' + key + '"]');
    if (!el) return;
    var pct = parseFloat(el.value) || 0;
    if (pct < 0) pct = 0; if (pct > 100) pct = 100;
    total += LB[key].vals[idx] * (pct / 100);
  });
  return Math.round(total * 10) / 10;
}

function updateLive() {
  var t = computeTbsa();
  var live = document.getElementById('burn-tbsa-live');
  if (live) live.textContent = t > 0 ? 'Computed TBSA: ' + t + '%' : '';
}

function calcBurn() {
  var wt = parseFloat(document.getElementById('burn-weight').value);
  var override = document.getElementById('burn-tbsa').value;
  var tbsa = override !== '' ? parseFloat(override) : computeTbsa();
  var el = document.getElementById('burn-result');
  if (!wt) { el.innerHTML = '<p style="color:var(--red);font-size:13px;">Enter weight (kg).</p>'; return; }
  if (!tbsa || tbsa <= 0) { el.innerHTML = '<p style="color:var(--red);font-size:13px;">Enter % involvement per region, or override TBSA.</p>'; return; }
  var total = Math.round(4 * wt * tbsa);
  var first8 = Math.round(total / 2);
  var rateFirst = Math.round(first8 / 8);
  var next16 = total - first8;
  var rateNext = Math.round(next16 / 16);
  var maint = wt <= 10 ? wt * 4 : wt <= 20 ? 40 + (wt - 10) * 2 : 60 + (wt - 20);
  maint = Math.round(maint);

  var html = '<div style="padding:10px 14px;border-radius:8px;background:#fee2e2;border:1.5px solid #ef4444;margin-bottom:10px;"><strong style="color:#dc2626;">Burn fluid resuscitation — ' + wt + ' kg, ' + tbsa + '% TBSA (2° or deeper)</strong></div>';
  html += '<div style="padding:12px;background:#fef2f2;border-radius:6px;margin-bottom:10px;"><strong>Parkland formula:</strong> 4 mL × kg × %TBSA = <strong>' + total + ' mL LR over 24 hours</strong>' +
          '<br>&nbsp;&nbsp;<strong>First 8 h</strong> (from time of burn): ' + first8 + ' mL (~<strong>' + rateFirst + ' mL/hr</strong>)' +
          '<br>&nbsp;&nbsp;<strong>Next 16 h</strong>: ' + next16 + ' mL (~<strong>' + rateNext + ' mL/hr</strong>)</div>';
  html += '<div style="padding:12px;background:var(--g50);border-radius:6px;margin-bottom:10px;"><strong>Plus maintenance fluids (4-2-1):</strong> ' + maint + ' mL/hr (D5 1/2NS ± 20 mEq KCl/L once UOP established). Consider dextrose in children &lt;30 kg.</div>';
  html += '<div style="padding:12px;background:var(--g50);border-radius:6px;margin-bottom:10px;"><strong>Titrate to UOP:</strong> target 1-2 mL/kg/hr (infants / children), 0.5-1 mL/kg/hr (adolescents). <strong>Clinical response trumps formula.</strong></div>';

  // Breakdown of what regions contributed
  var idx = ageIdx();
  var breakdown = '';
  Object.keys(LB).forEach(function(key) {
    var el2 = document.querySelector('[data-burn-region="' + key + '"]');
    if (!el2) return;
    var pct = parseFloat(el2.value) || 0;
    if (pct > 0) {
      var contrib = Math.round(LB[key].vals[idx] * pct / 100 * 10) / 10;
      breakdown += '<div>' + LB[key].label + ': ' + pct + '% of ' + LB[key].vals[idx] + '% = ' + contrib + '%</div>';
    }
  });
  if (breakdown) {
    html += '<details style="margin-bottom:10px;"><summary style="cursor:pointer;font-size:13px;font-weight:600;color:var(--g700);">Region breakdown</summary><div style="padding:10px;background:var(--g50);border-radius:6px;font-size:12px;margin-top:6px;">' + breakdown + '</div></details>';
  }

  html += '<h5 style="font-size:13px;font-weight:700;color:var(--g700);margin:14px 0 6px;">Other pearls</h5>';
  html += '<div style="padding:10px;background:var(--g50);border-radius:6px;font-size:12px;">';
  html += '<strong>Rule of palm:</strong> Patient\'s palm + fingers ≈ 1% TBSA — good for scattered burns.<br>';
  html += '<strong>First-degree burns DO NOT count</strong> toward TBSA or Parkland.<br>';
  html += '<strong>Analgesia:</strong> Morphine 0.05-0.1 mg/kg IV q2h, or fentanyl 1-2 mcg/kg IV q30-60 min.<br>';
  html += '<strong>Tetanus</strong> prophylaxis if indicated. Tdap/Td ± tetanus immunoglobulin.';
  html += '</div>';

  html += '<h5 style="font-size:13px;font-weight:700;color:var(--g700);margin:14px 0 6px;">Burn center referral (ABA)</h5>';
  html += '<div style="padding:10px;background:#fef3c7;border-radius:6px;font-size:12px;color:#92400e;">Partial-thickness &gt;10% TBSA; any full-thickness; face/hands/feet/genital/perineum/major joints; electrical/chemical/inhalation; associated trauma; significant comorbidities; pediatric burns in non-pediatric center.</div>';
  html += S.ref('ABA Advanced Burn Life Support (ABLS) 2018. Parkland formula: Baxter 1968. Lund-Browder 1944 chart (age-adjusted regions).');
  el.innerHTML = html;
}

export function init() {
  document.addEventListener('click', function(e) {
    if (e.target.id === 'btn-burn-calc' || e.target.closest('#btn-burn-calc')) calcBurn();
    if (e.target.id === 'btn-burn-reset' || e.target.closest('#btn-burn-reset')) resetParts();
    // Render body-parts table the first (or any) time the Burns sub-pill is activated
    var bp = e.target.closest && e.target.closest('[data-em="burns"]');
    if (bp) setTimeout(renderBodyParts, 0);
    // Also render if the top-level Bedside tab is clicked (ensures table ready before user navigates)
    var nav = e.target.closest && e.target.closest('[data-calc="bedside"]');
    if (nav) setTimeout(renderBodyParts, 50);
  });
  document.addEventListener('change', function(e) {
    if (e.target && e.target.id === 'burn-age') renderBodyParts();
  });
  document.addEventListener('input', function(e) {
    if (e.target && e.target.dataset && e.target.dataset.burnRegion) updateLive();
  });
  // Also attempt render on these events in case component mounts later
  document.addEventListener('DOMContentLoaded', renderBodyParts);
  document.addEventListener('tabChanged', function() { setTimeout(renderBodyParts, 100); });
  if (document.readyState !== 'loading') setTimeout(renderBodyParts, 0);
}