Respiratory Calculators
78 calculators
- A-a Oxygen GradientCalculates the alveolar-arterial oxygen gradient to assess for V/Q mismatch and diffusion defects.
- PEFR % PredictedCalculates peak expiratory flow rate as percentage of predicted to classify asthma severity.
- Pneumonia Severity Index (PSI/PORT)Predicts 30-day mortality in community-acquired pneumonia. Simplified from the full Fine/PORT score.
- BODE IndexPredicts mortality in COPD using BMI, airflow obstruction, dyspnoea, and exercise capacity.
- mMRC Dyspnoea ScaleGrades breathlessness severity to guide COPD management and pulmonary rehabilitation referral.
- Light's Criteria for Pleural EffusionDistinguishes exudative from transudative pleural effusions using protein and LDH ratios.
- FEV₁/FVC Ratio (Airflow Obstruction)Interprets spirometry FEV₁/FVC ratio to classify airflow obstruction severity per GOLD criteria.
- Pulmonary Embolism Severity Index (PESI)Predicts 30-day mortality in acute PE to guide disposition (inpatient vs outpatient management). Validated in multiple large cohorts.
- Simplified PESI (sPESI)Simplified version of PESI using 6 binary variables to predict 30-day mortality after acute PE. Easier to calculate bedside than the original PESI.
- Hestia Criteria for Outpatient PE Treatment11 clinical criteria to determine if a patient with acute PE is safe for outpatient (home) treatment. If ANY criterion is met, outpatient treatment is NOT recommended.
- YEARS Algorithm for PE DiagnosisStepwise algorithm combining 3 clinical items with D-dimer to exclude PE. Uses lower D-dimer threshold (500 μg/L) when ≥1 YEARS item present, higher threshold (1000 μg/L) when no YEARS items.
- Padua Prediction Score for VTE RiskEstimates VTE risk in hospitalised medical patients to guide thromboprophylaxis decisions.
- STOP-BANG Score for Obstructive Sleep ApnoeaScreens for moderate-to-severe obstructive sleep apnoea (OSA) using 8 binary questions. Used pre-operatively and in outpatient settings.
- Winters' Formula for Metabolic Acidosis CompensationPredicts the expected compensatory pCO₂ for a primary metabolic acidosis. A measured pCO₂ outside this range indicates a co-existing respiratory disorder.
- PaO₂/FiO₂ Ratio (P/F Ratio)Calculates the ratio of arterial oxygen tension to inspired oxygen fraction. Used to classify severity of hypoxaemic respiratory failure and diagnose ARDS per Berlin criteria.
- CRB-65 Score for Community PneumoniaSimplified pneumonia severity score not requiring urea measurement. Used in community and primary care settings to guide admission decisions in CAP.
- SMART-COP Score for Pneumonia SeverityPredicts need for intensive respiratory or vasopressor support (IRVS) in community-acquired pneumonia. Identifies patients who may require ICU-level care.
- RAPID Score for Pleural InfectionPredicts 3-month mortality in patients with pleural infection (empyema/complicated parapneumonic effusion) to guide management intensity. Validated in the MIST2 trial cohort.
- ARISCAT Score for Post-operative Pulmonary ComplicationsPredicts risk of postoperative pulmonary complications (atelectasis, respiratory failure, pleural effusion, pneumonia, pneumothorax, bronchospasm) in non-cardiac surgery patients.
- Arterial Oxygen Content (CaO₂)Calculates total arterial oxygen content — oxygen bound to haemoglobin plus dissolved in plasma. Used to assess oxygen delivery (DO₂ = CaO₂ × CO × 10).
- Age-Adjusted D-Dimer Threshold for PECalculates the age-adjusted D-dimer threshold for excluding PE in patients over 50. Reduces unnecessary CTPA in elderly patients with low-to-moderate pre-test probability. Formula: age × 10 μg/L.
- GOLD COPD ClassificationGOLD 2023 ABCD assessment tool for COPD combining symptom burden (CAT/mMRC) and exacerbation history to guide therapy.
- Berlin Criteria for ARDS2012 Berlin Definition of ARDS. Classifies severity by PaO₂/FiO₂ ratio with PEEP ≥ 5 cmH₂O.
- COPD Assessment Test (CAT)8-item patient-reported outcome measure quantifying COPD symptom impact on daily life. Validated for GOLD ABCD grouping.
- Fleischner Society Guidelines — Pulmonary Nodules2017 Fleischner Society guidelines for management of incidentally discovered pulmonary nodules on CT in adults ≥ 35 years.
- Mayo Clinic Solitary Pulmonary Nodule Malignancy RiskEstimates probability of malignancy in a solitary pulmonary nodule (SPN) using 6 independent predictors. Validated in multiple cohorts.
- ABG Interpretation GuideStepwise interpretation of arterial blood gas. Identifies primary acid-base disorder and degree of compensation.
- Wells' Criteria for Pulmonary EmbolismPre-test probability score for pulmonary embolism. Guides decisions regarding D-dimer testing and CT pulmonary angiography (CTPA) in suspected PE.
- Revised Geneva Score for Pulmonary EmbolismRevised Geneva Score for pre-test probability of pulmonary embolism. Fully objective score using only clinical and laboratory variables — no physician gestalt required.
- Bova Score for Pulmonary Embolism ComplicationsRisk stratification tool for intermediate-risk (haemodynamically stable) PE patients. Identifies those at risk of PE-related complications and death within 30 days.
- CURB-65 Score for Community-Acquired PneumoniaSeverity scoring for community-acquired pneumonia (CAP). Guides decision between outpatient, inpatient, and ICU care. British Thoracic Society standard score.
- Hamilton Score for DVT Clinical ProbabilityPredicts probability of deep vein thrombosis (DVT) in outpatients. An alternative to the Wells DVT score with similar performance.
- DECAF Score for Acute Exacerbation of COPDDyspnoea, Eosinopenia, Consolidation, Acidaemia, and Atrial Fibrillation (DECAF) score predicts in-hospital mortality in acute exacerbations of COPD.
- BAP-65 Score for Acute Exacerbation of COPDBUN, altered mental status, pulse ≥109, age ≥65 (BAP-65) score predicts in-hospital mortality and need for mechanical ventilation in AECOPD.
- MuLBSTA Score for Viral Pneumonia MortalityPredicts 90-day mortality in viral pneumonia. Validated in influenza and non-influenza viral pneumonias. MuLBSTA = Multilobar infiltrates, Lymphopenia, Bacterial co-infection, Smoking, Tumour, Age.
- Ottawa COPD Risk ScalePredicts 30-day serious adverse events (SAEs) in patients with AECOPD presenting to the emergency department. Score ≥1 associated with significantly increased SAE risk.
- ROX Index for Intubation after HFNCPredicts failure of high-flow nasal cannula (HFNC) in patients with acute hypoxaemic respiratory failure. ROX <3.85 at 12h predicts HFNC failure and need for intubation.
- Rapid Shallow Breathing Index (RSBI)Predicts successful extubation in mechanically ventilated patients. RSBI = respiratory rate / tidal volume (L). Values <105 predict weaning success.
- GAP Index for Idiopathic Pulmonary FibrosisGender, Age, Physiology (GAP) index predicts 1, 2, and 3-year mortality in idiopathic pulmonary fibrosis (IPF) using clinical and physiological variables.
- du Bois Score for IPF MortalityPredicts 1-year mortality in IPF from a single clinical visit using age, hospitalisation history, %predicted FVC, and 24-week FVC change. du Bois risk score ranges 0–100.
- LENT Prognostic Score for Malignant Pleural EffusionPredicts survival in patients with malignant pleural effusion (MPE). Scores LDH, ECOG status, NLR, and tumour type (LENT) to guide management decisions.
- Clinical Pulmonary Infection Score (CPIS) for VAPDiagnoses ventilator-associated pneumonia (VAP) using clinical, radiological, and microbiological criteria. Score >6 suggests VAP.
- Static Lung Compliance CalculationCalculates static lung compliance (Cstat) in mechanically ventilated patients. Reduced compliance (<60 mL/cmH₂O) indicates stiff lungs (ARDS, pneumonia, pulmonary oedema).
- SpO₂/FiO₂ (S/F) RatioNon-invasive surrogate for the PaO₂/FiO₂ ratio using pulse oximetry. Avoids arterial blood gas requirement. S/F ratio <315 correlates with ARDS (P/F <300).
- Brock University Lung Cancer Malignancy ScorePredicts malignancy probability in pulmonary nodules found on CT screening. Validated for nodules 6–30 mm. Used alongside Fleischner and BTS guidelines.
- DRIP Score for Drug-Resistant PneumoniaDrug Resistance in Pneumonia (DRIP) score identifies patients with community-acquired pneumonia at risk of drug-resistant pathogen infection (excluding MRSA/Pseudomonas HCAP criteria). Score ≥4 indicates high-risk.
- Murray Score for Acute Lung InjuryLung Injury Score (LIS) assesses severity of acute lung injury (ALI). Score ≥2.5 indicates severe ALI / ARDS. Used historically to assess ECMO candidacy.
- MACOCHA Score for Difficult Intubation in ICUPredicts difficult intubation in critically ill patients in the ICU. MACOCHA = Mallampati III or IV, Apnoea/OSA, reduced mobility of Cervical spine, Opening mouth, Coma, Hypoxaemia, non-Anaesthesiologist.
- HACOR Score for NIV Failure RiskHeart rate, Acidosis, Consciousness, Oxygenation, and Respiratory rate (HACOR) score predicts the risk of non-invasive ventilation (NIV) failure and need for intubation in patients with acute respiratory failure. Assessed at 1-2 hours after NIV initiation. Score above 5 predicts NIV failure with 72% sensitivity and 89% specificity. Validated by Liu et al. 2017 in 449 patients.
- PROMISE Score for Malignant Pleural Effusion PrognosisPrognostic score for patients with malignant pleural effusion (MPE). Predicts 3-month mortality. Based on LENT score variables plus Performance status. Score 0-7: score 0-1 = low risk (median survival above 12 months); 2-4 = intermediate; 5-7 = high risk (median survival 2 months). Helps guide intervention choices (indwelling pleural catheter vs talc pleurodesis). From Bibby et al. 2018.
- SCAP Score for Severe Community-Acquired PneumoniaSevere Community-Acquired Pneumonia (SCAP) score for predicting adverse outcomes (need for ICU, mechanical ventilation, death) in hospitalised CAP patients. 8-variable score. High score predicts severe outcome. Validated by Espana et al. 2006. Can be used alongside PSI/PORT and CURB-65 for ICU triage.
- Pulmonary Embolism Severity Index (PESI) -- Full VersionFull PESI score predicts 30-day mortality in acute pulmonary embolism. Classifies patients into 5 risk classes (I-V) based on age, sex, cancer, heart failure, COPD, heart rate, systolic BP, respiratory rate, temperature, mental status, and O2 saturation. Risk Class I-II (very low/low) may be suitable for outpatient treatment with DOAC. Validated in 11,000+ patients. Note: simplified PESI (sPESI) also available in this app.
- 4-Level Pulmonary Embolism Clinical Probability Score (4PEPS)Novel 4-level clinical probability score for pulmonary embolism that includes age and directly classifies patients into unlikely/low/intermediate/high PE probability. Developed by Roy et al. 2021 as an improvement over Wells and revised Geneva scores in the age of D-dimer adjustment. Designed to reduce unnecessary CTPA ordering. Validated in 1,746 patients.
- Lung Injury Prediction Score (LIPS)Lung Injury Prediction Score (LIPS) identifies patients at risk for developing Acute Lung Injury (ALI) / ARDS early in the hospital course (before ALI is established). Enables early preventive strategies (lung-protective ventilation, restrictive fluid strategy, avoidance of blood products). Validated by Gajic et al. 2011 in 5,584 patients. Score above 4 = high risk (ALI development rate 18% vs 3% for low risk).
- RESP Score for Respiratory ECMO Survival PredictionRespiratory ECMO Survival Prediction (RESP) score. Predicts in-hospital survival for patients receiving veno-venous ECMO (VV-ECMO) for acute respiratory failure. Based on 12 pre-ECMO variables. Score -22 to +15; Class I (score above 5) = 92% survival; Class V (score below -5) = 18% survival. Developed by Schmidt et al. 2014 from the ELSO registry of 2,355 patients. Used to guide ECMO candidacy decisions.
- ARISCAT Score for Postoperative Pulmonary ComplicationsAssesses risk of postoperative pulmonary complications (PPC) in adults undergoing surgery. Guides preoperative optimisation and perioperative respiratory monitoring.
- Berlin Criteria for Acute Respiratory Distress Syndrome (ARDS)2012 Berlin Definition of ARDS. Classifies ARDS severity (mild/moderate/severe) based on PaO₂/FiO₂ ratio while on PEEP ≥5 cmH₂O. Replaces the American-European Consensus Conference definition.
- CRB-65 Score for Community-Acquired PneumoniaCRB-65 score assesses severity of community-acquired pneumonia (CAP) in primary care or ED settings (no blood tests required). Guides hospital admission decisions.
- CURB-65 Score for Community-Acquired PneumoniaCURB-65 score predicts 30-day mortality in community-acquired pneumonia (CAP). Hospital-based version of CRB-65; requires blood urea measurement. Standard tool for CAP severity assessment.
- Brock University Lung Nodule Malignancy ModelEstimates probability of malignancy in incidental pulmonary nodules detected on CT. Based on the Pan-Canadian Early Detection of Lung Cancer Study. Guides surveillance and biopsy decisions.
- DRIP Score for Drug-Resistant PneumoniaDrug Resistance in Pneumonia (DRIP) score. Predicts risk of drug-resistant pneumonia pathogens to guide empirical antibiotic selection in CAP and HCAP patients.
- GOLD COPD Assessment (Spirometry + Symptom-Exacerbation)Global Initiative for Obstructive Lung Disease (GOLD) 2023 COPD classification. Grades spirometric severity (GOLD 1–4) and ABCD group based on symptom burden (mMRC/CAT) and exacerbation history.
- Gupta Postoperative Pneumonia Risk ScorePredicts risk of postoperative pneumonia requiring antibiotics or respiratory support within 30 days of non-cardiac surgery. Developed from the American College of Surgeons NSQIP database.
- DELTA-P Score for SVC Syndrome in TumourDutch-English LEMS Tumour Association Prediction (DELTA-P) Score. Predicts prognosis in superior vena cava (SVC) syndrome from lung malignancy and guides treatment decisions.
- EPIPHANY Index for PE in CancerPredicts clinical outcome of pulmonary embolism (PE) in cancer patients. Guides management intensity (outpatient vs admission vs ICU) and anticoagulation decisions.
- FEV1 % Predicted CalculatorCalculates the predicted FEV1 based on age, sex, and height using GLI-2012 reference equations. Used to interpret spirometry and classify COPD/restriction severity.
- Expected Peak Expiratory Flow (PEF) CalculatorEstimates predicted peak expiratory flow (PEF) based on sex, age, and height using Nunn-Gregg or ECCS reference equations. Used to assess asthma severity (% predicted PEF).
- Altitude-Adjusted PERC Rule for PEModified Pulmonary Embolism Rule-out Criteria (PERC) adjusted for altitude. At high altitudes (>4000 ft/1220 m), physiological SpO₂ is lower, so the cut-off is adjusted from 95% to 90% to maintain specificity.
- Asthma Severity Classification (GINA)GINA (Global Initiative for Asthma) 2023 severity and control classification. Guides step-up/step-down of inhaled therapy from Step 1 (PRN SABA) to Step 5 (biologic therapy).
- ROX Index (Risk of Intubation on HFNC)Predicts failure of high-flow nasal cannula (HFNC) oxygen therapy and need for intubation in acute hypoxaemic respiratory failure.
- NIV Failure Predictor ScorePredicts likelihood of non-invasive ventilation (NIV) failure in acute hypercapnic respiratory failure (AHRF) and COPD exacerbations.
- Oxygen Delivery (DO2) CalculatorCalculates oxygen delivery (DO2) to tissues from cardiac output, haemoglobin, and oxygen saturation. Normal DO2: 950-1150 mL/min.
- CO2 Retention Risk in COPD (High-Flow O2)Estimates risk of hypercapnic respiratory failure when administering supplemental oxygen in COPD patients. Guides target SpO2 selection (88-92%).
- Plethysmographic Variability Index (PVI) / Fluid ResponsivenessNon-invasive assessment of fluid responsiveness using respiratory variation in pulse oximetry plethysmographic waveform amplitude.
- Maximum Voluntary Ventilation (MVV) / Breathing ReserveEstimates maximum voluntary ventilation and breathing reserve index from FEV1. Used in pre-operative respiratory assessment.
- Physiological Dead Space (Bohr Equation)Calculates physiological dead space fraction using the Bohr-Enghoff equation. Elevated VD/VT (>0.6) predicts poor outcomes in ARDS.
- Asthma Control Test (ACT)Patient-completed 5-question test for asthma control over past 4 weeks. Score <=19 = not well controlled; score <=15 = very poorly controlled.
- Oxygen Saturation Target SelectionSelects appropriate SpO2 target range based on clinical condition. Prevents both hypoxia and oxygen toxicity (hyperoxia). Based on BTS Oxygen Guidelines.