1,329 calculators and references across 60 specialties, with formula confidence shown up front.
PROGRESS-CTO Success Index: Explanation and Clinical Context The PROGRESS-CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) Success Index is a validated scoring system that predicts the likelihood of successful percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO). This score incorporates five angiographic variables that independently predict pro
: Explanation and Clinical Context The PROLONG study examined patients with newly diagnosed heart failure and an initial left ventricular ejection fraction (LVEF) ≤35% who were protected temporarily by a wearable cardioverter-defibrillator (WCD) while guideline-directed medical therapy was initiated and optimized. The study defined criteria under which prolongation of the WCD wearing period — rather than immediate im
PROMISS Score (Postoperative Mortality): Explanation and Clinical Context The PROMISS score is a validated tool to predict 30-day postoperative mortality in adult surgical patients. It incorporates patient age, ASA physical status, emergency surgery, cardiac failure, and renal failure. The model uses logistic regression to calculate the predicted probability of postoperative death, allowing clinicians to identify hig
PROSPECT Echo Score: Explanation and Clinical Context The PROSPECT Echo Score is designed to predict the likelihood of a positive response to cardiac resynchronization therapy (CRT) based on echocardiographic and electrocardiographic parameters. Key variables include LVESV reduction percentage, QRS duration, mitral regurgitation severity, and left ventricular dyssynchrony index. Each parameter that meets a threshold
Prostate Cancer Gleason Score Explanation and Clinical Context The Gleason Score is a fundamental grading system for prostate cancer based on the microscopic appearance of tumor glands. The score combines the primary pattern which represents the predominant architectural pattern and the secondary pattern which represents the next most common pattern. The numeric sum reflects tumor aggressiveness and guides prognosis
PROTECHT Score: Explanation and Clinical Context The PROTECHT Score is a validated risk assessment model for predicting chemotherapy-associated venous thromboembolism (VTE) in patients with active cancer. It incorporates three key variables: primary tumor site (high-risk: pancreatic or gastric), history of previous VTE, and use of platinum-based or gemcitabine chemotherapy. Points are assigned to each variable (tumor
Explanation and Clinical Context Nitrogen balance represents the relationship between nitrogen intake primarily from dietary protein and nitrogen loss through urinary and non urinary pathways. This balance reflects the body protein turnover and helps clinicians evaluate catabolic stress nutritional adequacy and metabolic demands. Positive nitrogen balance indicates that nitrogen intake exceeds nitrogen loss which is
Protein Creatinine Ratio Explanation and Clinical Context The protein creatinine ratio is an accepted method to estimate daily urinary protein excretion without the need for a full twenty four hour urine collection. It provides a reliable assessment of proteinuria by comparing the concentration of urine protein to urine creatinine in a single spot sample. The ratio correlates closely with total daily protein excretio
PROVE-HF Biomarker Improvement Algorithm — Explanation and Clinical Context The PROVE-HF (Prospective Study of Biomarkers, Symptom Improvement, and Ventricular Remodeling During Sacubitril/Valsartan Therapy for Heart Failure) program examined whether changes in NT-proBNP after initiation of sacubitril/valsartan are associated with reverse cardiac remodeling and improvements in LV function. In the published cohort (Ja
PROVE-HF Surgical Score: Explanation and Clinical Context The PROVE-HF Surgical Score is a prognostic tool designed to predict postoperative mortality in patients with chronic heart failure undergoing major non-cardiac surgery. This score incorporates four clinical parameters: estimated glomerular filtration rate (eGFR), left ventricular ejection fraction (LVEF), hemoglobin levels, and brain natriuretic peptide (BNP)
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PSAX (Parasternal Short Axis) PSAX (Level Great Vessels � Focus on PV) RVOT : Right ventricular outflow tract, PV : Pulmonic valve, RA : Right atrium, Ao : Aorta, PA : Pulmonary artery, RPA : Right pulmonary artery, LPA : Left pulmonary artery, PSAX : Parasternal short axis. PSAX (Focus on PV and PA) Ao : Aorta, PA : Pulmonary artery, PSAX : Parasternal short axis, PV : Pulmonic valve, RVOT : Right ventricular outflo
PTSD Checklist PCL Five Explanation and Clinical Context PCL Five is a validated self report instrument that measures symptoms associated with post traumatic stress disorder based on DSM Five criteria. It evaluates intrusion avoidance negative alterations in cognition and mood and arousal symptoms. Respondents rate the severity of each symptom over the past month using a scale from zero not at all to four extremely.
Pediatric Ulcerative Colitis Activity Index PUCAI Explanation and Clinical Context The Pediatric Ulcerative Colitis Activity Index PUCAI is a validated noninvasive clinical score to assess disease activity in children with ulcerative colitis. The index includes six items abdominal pain rectal bleeding stool consistency stool frequency nocturnal stools and activity level. Each item is assigned points and the total sco
Pulmonary Arterial Compliance Index (PACi): Explanation and Clinical Context Pulmonary arterial compliance reflects the pulsatile component of right ventricular afterload, calculated as stroke volume divided by pulmonary arterial pulse pressure (sPAP − dPAP). Indexing to body surface area yields the Pulmonary Arterial Compliance Index (PACi): SVI/(sPAP − dPAP), expressed in mL·m-2 per mmHg. Compliance represents the
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Ascending Aorta (AA) diameter — same slice/level (mm) Sex (for sex-specific mPA normal limits) -- choose -- Male Female Pulmonary Artery Diameter Enlargement Ratio (CT-based): Explanation and Clinical Context The pulmonary artery–to–ascending aorta diameter ratio (PA/Ao) is obtained from axial chest CT at the level of the main pulmonary artery bifurcation, measuring the short-axis diameters of the main PA and ascendi
Pulmonary Artery Systolic Pressure (PASP) Estimate: Explanation and Clinical Context The PASP estimate is derived from Doppler echocardiography using the peak tricuspid regurgitation (TR) velocity and an estimate of right atrial (RA) pressure. The formula 4 × (TR velocity)^2 + RA pressure provides an approximation of pulmonary artery systolic pressure in mmHg. Elevated PASP may indicate pulmonary hypertension, right
Pulmonary Capillary Wedge Pressure Calculator: Explanation and Clinical Context Pulmonary capillary wedge pressure is a hemodynamic parameter that reflects left atrial pressure and is widely used as an indirect measure of left ventricular filling pressure. In clinical practice, PCWP plays an essential role in the evaluation of patients with suspected heart failure, assessment of hemodynamic congestion, and differenti
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Pulmonary Embolism Severity Index (PESI): Explanation and Clinical Context PESI is a validated risk stratification tool designed to estimate 30-day mortality in patients with acute pulmonary embolism. It incorporates 11 variables, including age, sex, comorbidities (cancer, heart failure, chronic lung disease), vital signs (heart rate, blood pressure, respiratory rate, temperature), altered mental status, and oxygen s
: Explanation and Clinical Context This calculator integrates non-invasive evidence to help differentiate pulmonary arterial hypertension (PAH) from PH due to left heart disease (PH-LHD). The H2FPEF score (Reddy et al., 2018) estimates HFpEF probability using atrial fibrillation (3), BMI >30 (2), ≥2 antihypertensives (1), age >60 (1), E/e' >9 (1), and PASP >35 (1). Scores ≥6 indicate a high likelihood of HFpEF, which
Pulmonary Valve Annulus (PVA) Z-score — explanation and clinical context This calculator implements the regression equations published by Pettersen et al. (J Am Soc Echocardiogr 2008) to compute a z-score for the pulmonary valve annulus relative to body size. Pettersen and colleagues derived nonlinear polynomial regression models on the natural-log transformed echocardiographic measurements against body surface area
Pulmonary Vascular Resistance Calculator Explanation and Clinical Context Pulmonary vascular resistance describes the afterload that the right ventricle must overcome to eject blood into the pulmonary circulation. It is derived from a hemodynamic relationship that integrates pressure gradients across the pulmonary vasculature and the magnitude of pulmonary blood flow. PVR reflects the degree of vasoconstriction, remo
Pulmonary Vascular Resistance Calculator Explanation and Clinical Context Pulmonary vascular resistance describes the afterload that the right ventricle must overcome to eject blood into the pulmonary circulation. It is derived from a hemodynamic relationship that integrates pressure gradients across the pulmonary vasculature and the magnitude of pulmonary blood flow. PVR reflects the degree of vasoconstriction, remo
Pulmonary Vascular Resistance (PVR) Estimate Using TRV/VTIRVOT: Explanation and Clinical Context Pulmonary vascular resistance (PVR) is a critical parameter in assessing pulmonary hypertension. The TRV/VTIRVOT method provides a non-invasive echocardiographic estimate of PVR, based on the relationship between the peak tricuspid regurgitation velocity (TRV) and the right ventricular outflow tract time-velocity integral
Pulmonary Vascular Resistance (PVR) Risk Tier: Explanation and Clinical Context Pulmonary Vascular Resistance (PVR) represents the afterload faced by the right ventricle and is calculated from the transpulmonary gradient (mean pulmonary artery pressure minus pulmonary artery wedge pressure) divided by cardiac output. It reflects the degree of obstruction within the pulmonary vasculature, primarily from remodeling or
Pulmonary Vasoreactivity Test Response Prediction Model: Explanation and Clinical Context This tool integrates a heuristic pre-test probability of a positive acute vasoreactivity test (AVT) response with established adult response criteria (Sitbon and Barst). Classic AVT response is defined by a ≥10 mmHg fall in mPAP to ≤40 mmHg without a drop in cardiac output (Sitbon), or ≥20% decrease in both mPAP and PVR with unc
Pulmonary-to-Systemic Flow Ratio (Qp/Qs): Explanation and Clinical Context The Pulmonary-to-Systemic Flow Ratio (Qp/Qs) is a hemodynamic index derived from the Fick principle that quantifies the relative blood flow between the pulmonary and systemic circulations. It is essential for the assessment of cardiac shunts such as atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosus (PDA)
Pulse Pressure: Explanation and Clinical Context Pulse pressure is the numerical difference between systolic and diastolic blood pressure. It reflects the interaction between stroke volume, aortic compliance, and ventricular function. A normal pulse pressure in healthy adults is approximately forty millimeters of mercury, although this value may vary with age. A widened pulse pressure may indicate increased arterial
Pulse Pressure Index (PPI): Explanation and Clinical Context Pulse Pressure Index (PPI) is the ratio of pulse pressure (PP) to systolic blood pressure (SBP), calculated as (SBP – DBP) / SBP. It provides a standardized measure of arterial stiffness and cardiovascular risk. Pulse pressure reflects the difference between systolic and diastolic blood pressure and serves as a surrogate for arterial compliance. Higher PPI
Pulse Wave Velocity (PWV): Explanation and Clinical Context Pulse Wave Velocity is a non-invasive measure of arterial stiffness and a strong independent predictor of cardiovascular events and mortality. It reflects the speed at which the blood pressure pulse propagates through the arterial tree, with higher values indicating stiffer arteries. Clinical assessment of PWV provides early detection of vascular aging and h
Explanation and Clinical Context The PURSUIT risk score was derived from a large international randomized trial of patients with unstable angina and non ST elevation myocardial infarction who received standard care with or without the glycoprotein two b three a inhibitor eptifibatide. It combines five bedside clinical features age sex worst Canadian Cardiovascular Society angina class in the preceding six weeks clini
PVC Burden Percentage: Explanation and Clinical Context PVC Burden Percentage represents the proportion of premature ventricular contractions (PVCs) relative to the total number of heartbeats over a 24-hour period as recorded by Holter monitoring or similar continuous ECG monitoring. A low PVC burden (<1%) is generally considered clinically insignificant, moderate burden (1–10%) may warrant follow-up in symptomatic p
PVI Mortality Score: Explanation and Clinical Context The PVI Mortality Score is a clinical tool used to estimate the risk of mortality in patients undergoing Peripheral Vascular Intervention (PVI). It incorporates factors such as age, creatinine levels, hemoglobin levels, diabetes, and smoking status to stratify patients into low, moderate, or high-risk categories. This score aids clinicians in decision-making, prio
PVI-ICD Mortality Risk Score: Explanation and Clinical Context The PACE risk score is a validated tool to estimate 1-year mortality risk for patients with an Implantable Cardioverter-Defibrillator (ICD) implanted for primary prevention. It incorporates four clinical variables: age >70 years, creatinine >2.0 mg/dL, ejection fraction <20%, and the presence of peripheral arterial disease (PAD). A total score of >3 indic
PYP Quantitative Uptake Index (QUI): Explanation and Clinical Context The PYP Quantitative Uptake Index (QUI) is a ratio of the radiotracer counts measured in the myocardial region of interest (ROI) to the contralateral chest ROI during 99mTc-Pyrophosphate (PYP) scintigraphy. It is used to quantify myocardial uptake and improve the diagnostic accuracy for transthyretin cardiac amyloidosis (ATTR-CA). A higher QUI valu
PYP Scintigraphy Visual Score: Explanation and Clinical Context PYP (99mTechnetium-Pyrophosphate) scintigraphy is a non-invasive imaging technique used to detect cardiac amyloidosis, particularly transthyretin amyloidosis (ATTR-CM). The visual score ranges from 0 to 3 based on myocardial radiotracer uptake relative to bone: - Grade 0: No cardiac uptake; ATTR-CM is very unlikely. - Grade 1: Mild uptake, less than bone