1,329 calculators and references across 60 specialties, with each tool type shown up front.
OptiVol Fluid Index (Medtronic CRT-D): explanation and clinical context The OptiVol Fluid Index is a device-derived metric based on changes in intrathoracic impedance measured by Medtronic CRT/ICD systems; it represents the cumulative difference between a device reference impedance and the measured daily intrathoracic impedance over time. A falling daily impedance (daily < reference) produces a positive deviation; wh
ORBIT Bleeding Score: Explanation and Clinical Context The ORBIT Bleeding Score is a validated clinical tool designed to predict the annual risk of major bleeding in patients with atrial fibrillation receiving oral anticoagulant therapy. Developed from the large-scale ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) study, it incorporates five easily available clinical variables: olde
Pain Intensity 0 I have no pain at the moment 1 The pain is very mild at the moment 2 The pain is moderate at the moment 3 The pain is fairly severe at the moment 4 The pain is very severe at the moment 5 The pain is the worst imaginable Personal Care 0 I can look after myself normally 1 It is painful to look after myself 2 I need some help but manage most tasks 3 I need help every day 4 I need help with most self ca
Outpatient Bleeding Risk Index (OBRI): Explanation and Clinical Context OBRI is a validated scoring system developed to predict the risk of major bleeding in outpatients receiving oral anticoagulant therapy, particularly warfarin. It assigns 1 point each for four clinical risk factors: age >65 years, history of stroke, history of gastrointestinal bleeding, and comorbid conditions including diabetes mellitus, cardiova
Explanation and Clinical Context This calculator estimates the expected ovulation day and the fertile window period based on the users average menstrual cycle length and the start date of their last menstrual period. Ovulation generally occurs around 14 days before the next menstrual cycle begins and fertility is highest within the window of five days before ovulation and one day after ovulation due to sperm survival
Oxygen Desaturation Index (ODI): Explanation and Clinical Context Oxygen Desaturation Index (ODI) quantifies the number of oxygen desaturation events per hour of sleep, typically defined as a ≥4% drop in oxygen saturation from baseline, lasting at least 10 seconds. It serves as a non-invasive and practical surrogate for the Apnea–Hypopnea Index (AHI) in evaluating sleep-disordered breathing (SDB). An elevated ODI ref
Oxygen Pulse (O₂ Pulse Index): Explanation and Clinical Context The Oxygen Pulse is defined as the amount of oxygen consumed per heartbeat during exercise, calculated by dividing VO₂ (oxygen uptake in mL/min) by heart rate (bpm). It serves as a non-invasive surrogate for stroke volume during exercise. Normal values in healthy adults range approximately from 10 to 15 mL/beat, but may vary with age, sex, fitness level,
Oxygen Uptake Efficiency Slope (OUES): Explanation and Clinical Context OUES is a submaximal index derived from cardiopulmonary exercise testing (CPET) that quantifies the efficiency of oxygen uptake relative to ventilation. It is calculated using the linear relationship between oxygen consumption (VO2) and the logarithm of minute ventilation (VE), typically expressed as VO2 = a × log10(VE) + b, where the slope 'a' r
FiO2 Mean Airway Pressure MAP PaO2 Oxygenation Index OI Explanation and Clinical Context Oxygenation Index is a validated measure used to quantify the severity of hypoxic respiratory failure and to evaluate the degree of ventilatory support required to maintain adequate oxygenation. The formula incorporates the fraction of inspired oxygen with mean airway pressure and arterial oxygen tension which allows clinicians t
P-wave Axis Deviation Index: Explanation and Clinical Context The P-wave axis is calculated using the frontal plane ECG leads I and aVF to estimate atrial depolarization direction. A normal P-wave axis ranges from 30° to 75° in adults. Values outside this range indicate potential right or left atrial enlargement, atrial conduction abnormalities, or underlying structural heart disease. Abnormal P-wave axis has been as
P-wave Dispersion (PWD): Explanation and Clinical Context P-wave Dispersion is defined as the difference between the maximum and minimum P-wave durations measured on a standard 12-lead ECG. It reflects the heterogeneity of atrial conduction and has been widely studied as a predictor of atrial fibrillation (AF) in both structural heart disease and healthy populations. Increased PWD indicates inhomogeneous and disconti
Pacemaker Requirement Index after TAVR: Explanation and Clinical Context This calculator estimates the probability of requiring a permanent pacemaker (PPM) within about 60 days after Transcatheter Aortic Valve Replacement (TAVR). Key independent predictors include pre-existing right bundle branch block (RBBB), a larger pre-procedural aortic valve area (AVA), and a higher ratio of post- to pre-procedural AVA, reflecti
Pacing-Induced Cardiomyopathy (PICM) Score: Explanation and Clinical Context The PICM Score estimates the risk of developing pacing-induced cardiomyopathy in patients with chronic right ventricular pacing. This condition is characterized by left ventricular systolic dysfunction caused by ventricular dyssynchrony induced by long-term RV pacing. The score incorporates the percentage of RV pacing, baseline left ventricu
PADIT Score: Explanation and Clinical Context The PADIT Score is a validated tool to estimate the risk of cardiac implantable electronic device (CIED) infection based on patient and procedural factors. It incorporates five key variables: prior device infection, number of device procedures (first implant, replacement, or upgrade), device type (pacemaker, ICD, CRT), immunocompromised status, and renal dysfunction. Each
: Explanation and Clinical Context The Padua Prediction Score is a validated clinical tool used to estimate the risk of venous thromboembolism (VTE) in hospitalized medical patients. Each risk factor is assigned a specific point value based on its contribution to VTE risk. High-risk patients (score >4) are candidates for thromboprophylaxis, whereas low-risk patients (score <4) usually do not require routine prophylax
PAH-CHD Survival Model: Explanation and Clinical Context This model estimates the survival probability of patients with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD). It incorporates clinical parameters such as age, oxygen saturation, WHO functional class, pulmonary vascular resistance index (PVRi), and the Qp/Qs ratio. The model provides a simplified approach to assist clinicians
The Pain Disability Index evaluates how pain interferes with daily activities. Enter the score for each domain below. Each item ranges from zero to ten. Pain Disability Index Explanation and Clinical Context The Pain Disability Index is a validated multidimensional instrument designed to measure how much chronic pain affects daily functioning. It evaluates seven domains of life which include family and home responsib
PAMI Risk Score: Comprehensive Explanation and Clinical Context The PAMI (Primary Angioplasty in Myocardial Infarction) Risk Score is a clinical tool developed to predict 30-day mortality in patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). It uses seven readily available clinical variables: age, comorbidities, heart rate, systolic blood pressure,
AWARD-Class / PARADIGM-HF Responder context and interpretation The AWARD-Class score (derived from a two-center real-world cohort) is an easy-to-calculate index intended to predict a 1-year “super-response” to sacubitril/valsartan, defined in the derivation study as absence of HF admission/transplant/death plus either ≥50% NT-proBNP reduction and/or ≥10-point increase in LVEF. The score uses six routinely available c
— Explanation and Clinical Context PARADISE-MI was a multinational randomized trial that enrolled high-risk patients early after acute myocardial infarction if they had transient pulmonary congestion or LVEF ≤40% and at least one additional risk factor (age ≥70 years, eGFR <60 mL/min/1.73 m², diabetes, prior myocardial infarction, atrial fibrillation, LVEF <30%, Killip class ≥III, or STEMI without reperfusion). The t
PARAGON-HF Response Score: Explanation and Clinical Context The PARAGON-HF Response Score is an exploratory model derived from the PARAGON-HF trial, developed to identify patients with heart failure with preserved ejection fraction (HFpEF) who are most likely to experience clinical and biomarker improvement with sacubitril/valsartan therapy. This score integrates demographic and clinical parameters — including age, s
Aortic Regurgitation Bolded qualitative and semiquantitative signs are considered specific for their AR grade. Color Doppler usually performed at a Nyquist limit of 50-70 cm/sec. (1) Unless there are other reasons for LV dilation. (2) Specific in normal LV function, in absence of causes of volume overload. Exception: acute AR, in which chambers have not had time to dilate. (3) PHT is shortened with increasing LV dias
Mitral stenosis *Specific findings Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice (2009)
Aortic Stenosis Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis: A Focused Update from the EACVI and the ASE (2017)
Mitral regurgitation Bolded qualitative and semiquantitative signs are considered specific for their MR grade. All parameters have limitations, and an integrated approach must be used that weighs the strength of each echocardiographic measurement. All signs and measures should be interpreted in an individualized manner that accounts for body size, sex, and all other patient characteristics. (1) This pertains mostly t
Pulmonary Stenosis Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice (2009)
Pulmonary Regurgitation (1) Unless there are other reasons for RV enlargement. (2) Exception: acute PR. (3) Identifies a CMR-derived PR fraction >40%. (4) Steep deceleration is not specific for severe PR. (5) Not reliable in the presence of high RV end diastolic pressure. (6) Defined as the duration of the PR signal divided by the total duration of diastole, with this cutoff identifying a CMR-derived PR fraction > 25
Tricuspid Regurgitation Bolded signs are considered specific for their tricuspid regurgitation grade. (1) RV and RA size can be within the “normal” range in patients with acute severe TR. (2) Signs are nonspecific and are influenced by many other factors (RV diastolic function, atrial fibrillation, RA pressure). (3) There are little data to support further separation of these values. ASE Recommendations for Noninvasi
Tricuspid Stenosis *Specific findings Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice (2009)
Paravalvular Leak (PVL) Severity Score: Rationale, Calculations, and Clinical Use This tool consolidates validated catheter-based hemodynamic indices to grade PVL severity immediately after transcatheter aortic valve replacement (TAVR). The core metric is the Aortic Regurgitation Index (ARI), defined as ((DBP − LVEDP) / SBP) × 100. Lower values imply greater diastolic run-off into the LV and more severe PVL. In the s
PARIS Bleeding Risk Score: Comprehensive Explanation and Clinical Context The PARIS Bleeding Risk Score is a validated clinical tool developed to estimate the risk of major bleeding in patients undergoing dual antiplatelet therapy after percutaneous coronary intervention. It incorporates simple bedside variables that reflect age related vulnerability, hemodynamic reserve, underlying comorbidities, and previous bleedi
Comprehensive Explanation and Clinical Context: The PARIS Thrombosis Risk Score (Patterns of Non-Adherence to Anti-Platelet Regimens in Stented Patients) is a clinical tool designed to predict the likelihood of stent thrombosis and major adverse cardiac events (MACE) among patients receiving dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI). Variables and Scoring: The score is derived fr
Parkland Formula Explanation and Clinical Context Parkland formula, also known as Baxter formula, is a widely accepted method for estimating initial fluid resuscitation requirements in patients with significant burn injuries. The formula uses two primary variables which are the patient weight in kilograms and the percentage of total body surface area affected by partial thickness or full thickness burns. The total ca
Parsonnet Score: Explanation and Clinical Context The Parsonnet Score is a widely used cardiac surgical risk stratification tool developed to predict operative mortality in patients undergoing cardiac surgery. It assigns points based on preoperative risk factors, including age, sex, history of myocardial infarction, congestive heart failure, and urgency of the procedure. The cumulative score correlates with the estim
PARTNER Risk Model (TAVR substudies): Explanation and Clinical Context The PARTNER Risk Model is a validated tool to estimate 30-day mortality risk after transcatheter aortic valve replacement (TAVR) in high-risk or inoperable patients. It uses clinical variables available pre-procedure, including age, serum creatinine, NYHA functional class III/IV, body mass index (BMI), and serum albumin. The model calculates the p
Erythema Head Induration Head Scaling Head Area Head Erythema Upper Limbs Induration Upper Limbs Scaling Upper Limbs Area Upper Limbs Erythema Trunk Induration Trunk Scaling Trunk Area Trunk Erythema Lower Limbs Induration Lower Limbs Scaling Lower Limbs Area Lower Limbs PASI Psoriasis Severity Score Explanation and Clinical Context PASI is one of the most widely accepted scoring systems to quantify the severity of p
PCAT Attenuation Index: Explanation and Clinical Context PCAT Attenuation Index measures the mean CT attenuation of pericoronary adipose tissue surrounding coronary arteries in Hounsfield Units (HU). It serves as a non-invasive biomarker of coronary inflammation, with higher (less negative) values reflecting greater inflammatory activity in the vessel wall. It is derived from coronary CT angiography by averaging the
PCOS Cardiometabolic Risk Index: Explanation and Clinical Context The PCOS Cardiometabolic Risk Index (PCRI) is a composite score designed to estimate the risk of metabolic and cardiovascular complications in women with Polycystic Ovary Syndrome (PCOS). It integrates age, BMI, waist circumference, fasting glucose, triglycerides, and HDL cholesterol into a single predictive metric. Higher scores indicate greater cardi
PDA Severity Score (PDAsc) — Explanation and Clinical Context The PDA Severity Score (PDAsc) is a multivariable echocardiography-based prognostic index developed to quantify early hemodynamic significance of a patent ductus arteriosus in very preterm infants and predict the composite outcome of chronic lung disease or death before discharge. The score combines gestational age, echocardiographic PDA diameter (pulmonar
Peak TRV Risk Stratification: Explanation and Clinical Context Peak tricuspid regurgitant velocity (TRV) is a key echocardiographic parameter used to estimate pulmonary artery systolic pressure (PASP) and assess the probability of pulmonary hypertension (PH). It is derived from continuous-wave Doppler measurement of the tricuspid regurgitation jet and incorporated into the simplified Bernoulli equation (ΔP = 4 × TRV²
Clinical reference for Peak VO2 Percent Predicted For Athlete Classification, with practical context for use alongside current guidance and professional judgment.
Pearl Contraceptive Index Explanation and Clinical Context The Pearl Index is a commonly used measure of contraceptive effectiveness expressed as the number of unintended pregnancies occurring per 100 woman years of exposure. It is calculated by dividing the total number of pregnancies by the total woman years of exposure and then multiplying by 100. When exposure is reported in months the equivalent formula is pregn
Age in years Standing balance score Walking stability score Gross motor coordination score Pediatric Balance and Motor Scale Explanation and Clinical Context The Pediatric Balance and Motor Scale is a structured clinical assessment designed to evaluate balance stability gait control and motor coordination in children across a wide developmental range. These domains reflect essential neuromotor functions that support
Explanation and Clinical Context This tool estimates total circulating blood volume in pediatric patients using body weight and age group. The calculation follows a simple approach where estimated blood volume equals body weight in kilogram multiplied by an age specific blood volume factor expressed in milliliter per kilogram. Typical average factors used in this calculator are one hundred milliliter per kilogram for
Weight (kg) Height (cm) Age (years) Sex Select Male Female Explanation and Clinical Context Pediatric BMI percentile is a screening parameter that evaluates body mass index relative to children of the same sex and age. It helps clinicians classify nutritional status and detect underweight overweight and obesity early. Body mass index alone is not enough in pediatrics because normal BMI values change with growth there
CRISP Pediatric Cardiac Catheterization Risk Score: Explanation and Clinical Context The CRISP (Catheterization RISk Score for Pediatrics) model is a validated risk tool to predict serious adverse events (SAEs) in pediatric patients undergoing cardiac catheterization. } It incorporates multiple pre‑procedural variables (age, procedure risk level, hemodynamic vulnerability, use of inotropes or mechanical support, emer
Pediatric Cardiomyopathy Mortality Score: Explanation and Clinical Context The Pediatric Cardiomyopathy Mortality Score is a clinical tool designed to estimate the 1-year mortality risk in children diagnosed with primary cardiomyopathy. It integrates patient age, left ventricular systolic function (fractional shortening), left ventricular size (LVEDD z-score), serum BNP levels, and the presence of arrhythmias. Lower
Pediatric Centor score for pharyngitis explanation and clinical context The pediatric Centor score applies classical Centor criteria to children with acute sore throat. It sums four simple clinical features which are history of fever at least thirty eight degree Celsius, tonsillar exudate or swelling, tender anterior cervical lymph nodes, and absence of cough. Each feature scores one point so the total score in this
Pediatric Crohn Disease Activity Index PCDAI Explanation and Clinical Context The Pediatric Crohn Disease Activity Index is a validated composite instrument used to quantify disease activity in children with Crohn disease. It combines history items including abdominal pain stool pattern and general well being with physical examination findings growth and perianal assessment and laboratory markers including hematocrit
Pediatric Early Warning Score PEWS Explanation and Clinical Context Pediatric Early Warning Score is a structured bedside tool used to identify early signs of clinical deterioration in hospitalized children. It organizes the evaluation into three domains which are behavior cardiovascular status and respiratory status. Each domain assigns a score from zero to three based on deviation from normal physiology and the sum
Explanation and Clinical Context The pediatric glomerular filtration rate estimator uses the bedside Schwartz equation which provides a practical method to estimate kidney filtration capacity in children and adolescents. It relies on two simple variables height in centimeters and serum creatinine in mg per dL. The equation produces a value normalized to a standard body surface area of 1.73 square meters which allows
Pediatric Heart Failure Severity Index (Ross Classification): Explanation and Clinical Context The Ross Classification is a widely used clinical scoring system to assess the severity of heart failure in infants and young children. It evaluates symptoms such as feeding difficulty, tachypnea, diaphoresis, hepatomegaly, and growth. Class I represents asymptomatic patients, Class II indicates mild symptoms with exertion
Pediatric LV Mass (LVM) and Z-score: Explanation and Clinical Context Left ventricular mass (LVM) estimated from M-mode echocardiography is commonly calculated using the Devereux formula (described here). Because children vary widely in body size, LVM must be normalized for body size; common approaches include indexing to height (allometric index, e.g., height^2.7), indexing to body surface area (BSA), or using ce
Pediatric Myocarditis Severity Index: Explanation and Clinical Context The Pediatric Myocarditis Severity Index (PMSI) is a clinical tool designed to stratify the risk and predict outcomes in children with acute myocarditis. It incorporates key variables including age, heart rate, left ventricular ejection fraction (LVEF), serum troponin I levels, and BNP levels to provide an integrated risk score. A higher PMSI scor
Pediatric Pulmonary Hypertension Risk Index: Explanation and Clinical Context The Pediatric Pulmonary Hypertension Risk Index is a validated scoring system to estimate prognosis in children with pulmonary arterial hypertension (PAH). It combines clinical (WHO Functional Class), biomarker (NT-proBNP), exercise capacity (6-minute walk distance), hemodynamic parameters (right atrial pressure and cardiac index) to strati
: Explanation and Clinical Context This calculator assists clinicians to estimate packed red cell transfusion volume for pediatric patients. The commonly used dose for red cell transfusion in children is four milliliters per kilogram per one gram per deciliter expected increase in hemoglobin concentration. This formula provides an approximate volume to achieve the desired hemoglobin rise in stable patients. Individua
Explanation and Clinical Context Vital signs in children vary widely according to age therefore accurate interpretation requires age specific reference ranges. This calculator provides reference values for heart rate respiratory rate and systolic blood pressure across pediatric developmental stages. Newborns and infants normally have higher heart rate and respiratory rate reflecting high metabolic demand and smaller
Guided clinical worksheet for PEGASUS-TIMI 54 Long-term DAPT Benefit Index (PEGASUS DAPT Benefit Calculator). Organize relevant information, review it with current guidance, and save a private summary on this device.
Peguero–Lo Presti Index — explanation and clinical context The Peguero–Lo Presti index is an electrocardiographic voltage measurement calculated as the sum of the amplitude of the deepest S wave in any lead (Sdeepest) plus the amplitude of the S wave in lead V4 (SV4). The index is expressed in millivolts (mV). In the original derivation and subsequent validations, sex-specific cutoffs were recommended: a value > 2.3
Pain during menstruation Pain during intercourse Pain during pelvic examination Pain during urination Pain during bowel movement Chronic pelvic pain at rest Explanation and Clinical Context The Pelvic Pain Index is a structured scoring method used to quantify the severity of pelvic pain across several clinical situations including menstruation intercourse pelvic examination urination bowel movement and pain at rest.