Point-of-care calculators for anesthesia and perioperative practice. Click any card — the calculator opens right here in a pop-up. All computation happens in your browser; no patient data is transmitted or stored.
Perioperative Assessment & Scoring
Preoperative status and risk communication.
ASA Physical Status
Six-point classification of overall preoperative health, with the emergency modifier.
ASA I–VI · “E” suffix
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Modified Aldrete Score
Five-domain PACU recovery score — physiological readiness for ward transfer.
0–10 · discharge ≥ 9 · rescore q15 min
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STOP-BANG (OSA Screen)
Eight-item obstructive sleep apnea screen validated in surgical patients — flags moderate-to-severe OSA risk.
0–8 · ≥ 5 high risk · refinement alert
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Revised Cardiac Risk Index (RCRI)
Lee Index for perioperative cardiac risk — six predictors, Classes I–IV with event-rate context.
0–6 · Class I–IV · ACC/AHA framing
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Caprini VTE Risk Score
2005 risk-assessment model — tiered checklist mapping to prophylaxis intensity, with the ASRA neuraxial note.
0 / 1–2 / 3–4 / ≥ 5 · uncapped · documentable
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Drugs & Infusions
Dosing limits and dose ↔ pump-rate conversions for everyday agents.
Local Anesthetic Maximum Dose
Maximum recommended dose and volume for common local anesthetics, plain or with epinephrine.
mg/kg · absolute caps · max volume
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Local Anesthetic Max Dose — Pediatric
Pediatric maxima with age-based weight estimation for the resus trolley.
mg/kg · weight from age · infant cautions
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Infusion Rate Converter
Convert prescribed dose to pump rate and back — mcg/kg/min, mg/kg/hr, mL/hr and more.
dose ↔ mL/hr · bag notation
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Opioid MME Converter
Total daily opioid load summed across up to four agents — CDC 2022 factors, methadone tiered automatically.
CDC 2022 · 4 slots · ≥ 50 / ≥ 90 thresholds
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Sugammadex Dosing
Depth-of-block dosing — 2 / 4 / 16 mg/kg tiers with the agent guards, volumes, and re-dosing wait times.
T2 · PTC 1–2 · 16 rescue · wait-time table
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Pediatric Resuscitation Card
Weight, ETT sizing, and the full weight-based drug card with draw-up volumes — print, verify, tape.
mg + mL per drug · caps shown · print-first
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Dosing Weights (IBW · AdjBW · LBW)
Same patient, four answers — Devine, adjusted, and Janmahasatian lean weight with the per-drug conventions.
propofol LBW · rocuronium IBW · sux actual · table included
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Fluids & Transfusion
Blood volume and transfusion-threshold planning.
Maximum Allowable Blood Loss (MABL)
Isovolemic loss tolerated before reaching the chosen hematocrit trigger, with remaining margin.
EBV · Hct trigger · remaining margin
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4-2-1 Maintenance Fluids
Holliday–Segar maintenance rate with fasting-deficit estimate for the NPO patient.
4-2-1 · 100/50/20 · NPO deficit
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Hemodynamics
Bedside cardiovascular numbers and their perfusion targets.
Mean Arterial Pressure (MAP)
MAP from systolic and diastolic pressure, with perfusion-target bands and kPa toggle.
DBP + PP/3 · impossible inputs blocked
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Systemic Vascular Resistance (SVR)
Afterload index from MAP, CVP and cardiac output — Wood units and indexed values included.
80 × (MAP − CVP) / CO · SVRI · cmH₂O toggle
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Shock Index (HR/SBP)
Heart-rate-to-systolic screen that flags compensated shock and occult hemorrhage before the BP falls.
0.5–0.7 normal · trend-friendly
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Cerebral Perfusion Pressure (CPP)
MAP − ICP with TBI targets — and an ICP warning that a target CPP never excuses raised pressure.
60–70 target · ICP ≥ 22 alert · MAP cross-hairs
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Oxygen Content & Delivery (CaO₂ · DO₂)
The full oxygen cascade — content, DO₂/DO₂I, and with a venous sample: VO₂ and extraction ratio.
1.34 · 0.003 · DO₂I 500–600 · O₂ER
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Airway & Ventilation
Lung-protective ventilation sizing and gas-exchange metrics.
PBW & Lung-Protective Tidal Volume
ARDSNet tidal volume from predicted body weight — height-based, immune to obesity.
4–8 mL/kg · 6 benchmark · no weight field, by design
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RSBI (Rapid–Shallow Breathing Index)
f/VT screen for extubation readiness during spontaneous breathing trials — PS-aware.
f/VT · < 105 favorable · titration cross-hairs
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Compliance & Driving Pressure
Cstat and ΔP from tidal volume, plateau and PEEP — with the VT that brings ΔP to 15.
VT ÷ ΔP · target ≤ 15 · titration cross-hair
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Dead-Space Fraction (Bohr–Enghoff)
Ventilatory efficiency from PaCO₂ and ETCO₂ — gradient included, metric honestly labeled, PE signature taught.
(PaCO₂−ETCO₂)/PaCO₂ · gradient 2–5 · apparatus excluded
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Critical Care & Monitoring
Structured observation scores for the deteriorating and sedated patient.
NEWS2 (Early Warning Score)
Seven-parameter deterioration screen with live band scoring, both saturation scales, and the single-3 alert.
0–20 · Scale 1/2 · escalation-aware
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RASS (Richmond Scale)
The ICU sedation standard from +4 to −5 — with the CAM-ICU gateway built in.
+4 → −5 · CAM-ICU window
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SOFA (Organ Failure Assessment)
Six-domain dysfunction score with computed P/F, worst-of-two renal, and named organ-failure flags.
0–24 · ΔSOFA ≥ 2 = sepsis-3 · trend first
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APACHE II
The classic ICU severity score — twelve worst-in-24h physiology variables, age, and chronic health, with every band shown live.
0–71 · ARF doubling · chronic criteria built in
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SAPS II
The European ICU severity score — worst-in-24h physiology, chronic trio, and the derivation-cohort mortality equation computed.
vent-gated P/F · BUN not creatinine · 1993 probability
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Respiratory & Blood Gases
Oxygenation and ventilation metrics from arterial gases.
A-a Gradient
Alveolar–arterial oxygen gradient with age-adjusted expectation and P/F ratio.
alveolar gas equation · altitude aware
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Winters Formula
Expected PaCO₂ in metabolic acidosis — is respiratory compensation appropriate?
1.5 × HCO₃⁻ + 8 ± 2 · HH consistency check
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Anion Gap (with albumin correction)
Unmeasured-anion screen for metabolic acidosis — albumin-corrected, with delta ratio.
Na − (Cl + HCO₃⁻) · +2.5/g/dL · Δ ratio
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General & Metabolic
Everyday baseline measures with perioperative context.
Body Mass Index (BMI)
BMI with WHO classification and perioperative dosing-positioning notes.
kg ↔ lb · cm ↔ in
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Corrected Sodium in Hyperglycemia
Dilutional hyponatremia correction — Katz and Hillier factors, auto-selected by glucose level.
+1.6 / +2.4 per 100 mg/dL · both shown
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Body Surface Area (Mosteller)
The normalizing variable for cardiac indices, GFR indexing, and BSA-dosed drugs — formula spread shown.
√(ht×wt/3600) · Du Bois & Haycock comparisons · index discipline
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Renal
Kidney function, dosing weights, and electrolyte corrections.
Cockcroft-Gault Creatinine Clearance
Drug-label renal estimate — with the actual / ideal / adjusted weight basis chosen explicitly.
(140−age)×wt/72×SCr · KDIGO-aligned · steady-state only
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eGFR — CKD-EPI 2021 (Race-Free)
The laboratory-standard GFR estimate for CKD staging — indexed value with optional de-indexing for body-size extremes.
G1–G5 · 142 × min/max · race-free 2021
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FENa / FEUrea
Fractional excretion of sodium and urea for the AKI differential — diuretic-aware, with FEUrea promoted when it counts.
< 1% / < 35% prerenal · mixed urea units safe · U/P ratios shown
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Corrected Calcium (± Albumin)
Total calcium adjusted for albumin binding — mixed unit families safe, ionized-Ca caveats taught.
+0.8 per g/dL below 4.0 · 8.5–10.5 normal · myeloma trap
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Serum Osmolality & Osmolar Gap
Calculated osmolality and the unmeasured-osmole screen — ethanol-residual analysis, TURP-aware, VPO caveat built in.
2Na + Glu/18 + BUN/2.8 · gap < 10 normal · EtOH/3.7
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Hepatic & Transplant
Liver-disease severity and transplant-prioritization scores.
MELD 3.0
90-day mortality in advanced liver disease — the OPTN allocation formula with every floor, cap, and interaction term shown.
0–40 · albumin + sex term · dialysis rule
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Child-Pugh Score
Chronic liver disease severity across five domains — with the PBC/PSC bilirubin variant and perioperative risk context.
5–15 · Classes A–C · PBC variant
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Equipment & Gases
Cylinder contents, gas supply, and environmental footprint.
Cylinder Duration (O₂ · N₂O · Air)
How long the cylinder lasts at a given flow — weight-based for nitrous oxide, where the gauge lies.
D/E cylinders · reserve-aware · N₂O weight method
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Anesthetic Gas Carbon Footprint
CO₂e per case from flow, agent, and duration — with the counterfactuals quantified: low-flow, sevoflurane swap, N₂O removal.
kg CO₂e · car-km & tree-years · lever ranking
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Obstetric & Neonatal
Assessment of the newborn and the obstetric patient.
AnesthCalc — educational decision support only, not a substitute for clinical judgment. Each calculator shows its references, version, and review date. More calculators in development.