1,329 calculators and references across 60 specialties, with formula confidence shown up front.
Alveolar Gas Equation Explanation and Clinical Context The alveolar gas equation estimates alveolar oxygen partial pressure PAO2 using inspired oxygen fraction FiO2, barometric pressure Patm, water vapor pressure PH2O, arterial carbon dioxide PaCO2 and respiratory quotient RQ. The formula used here is PAO2 equals FiO2 times Patm minus PH2O minus PaCO2 divided by RQ. Normal PAO2 depends on FiO2 and altitude. At sea le
Asthma Predictive Index Explanation and Clinical Context The Asthma Predictive Index is a clinical tool developed to identify young children who have recurrent wheezing and who are at higher risk of developing persistent asthma later in childhood. The index is based on the presence of at least three wheezing episodes in one year combined with either one major criterion or two minor criteria. Major criteria include pa
BODE Index for COPD Prognosis Explanation and Clinical Context The BODE index is a multidimensional prognostic tool that combines body mass index BMI airflow obstruction measured as FEV1 percent predicted dyspnea assessed by the modified Medical Research Council mMRC scale and exercise capacity measured as six minute walk distance in meters. Each component is scored and the total ranges from zero to ten points. Highe
COPD GOLD Staging Explanation and Clinical Context Chronic Obstructive Pulmonary Disease is assessed using the Global Initiative for Chronic Obstructive Lung Disease classification which relies on the value of forced expiratory volume in one second expressed as percent predicted. This parameter reflects the degree of airflow limitation and correlates with severity of disease and symptom burden. The GOLD system places
CURB65 Pneumonia Severity Score Explanation and Clinical Context CURB65 assigns one point for each of five readily available clinical variables at initial assessment: new onset confusion, blood urea greater than 7 mmol per liter, respiratory rate of 30 breaths per minute or more, low blood pressure defined as systolic less than 90 mm Hg or diastolic 60 mm Hg or less, and age 65 years or older. The total score ranges
Measured DLCO Predicted DLCO DLCO Diffusing Capacity for Carbon Monoxide Explanation and Clinical Context DLCO describes the ability of the lungs to transfer carbon monoxide from the alveoli into the pulmonary capillary blood and is one of the most sensitive indicators of gas exchange function. A normal DLCO reflects adequate alveolar surface area, intact alveolar capillary membrane, and sufficient pulmonary blood vo
FEV1 FVC Ratio Analyzer Explanation and Clinical Context The FEV1 FVC ratio is the proportion of forced expiratory volume in the first second to the forced vital capacity expressed as a percentage. A lower ratio reflects a disproportionate reduction in airflow relative to volume which suggests airflow obstruction. In routine clinical practice a fixed threshold of 70 percent after bronchodilator is commonly used to in
Full Pulmonary Function Test Interpretation Explanation and Clinical Context Pulmonary function testing provides an integrated view of airway physiology. It assesses airflow mechanics lung volume distribution and gas transfer efficiency. Each component reflects a different dimension of cardiopulmonary function and supports a structured evaluation of respiratory disorders. The FEV1 FVC ratio helps identify obstruction
Revised Geneva Score for Pulmonary Embolism Explanation and Clinical Context The Revised Geneva Score is an objective clinical prediction rule that estimates the probability of pulmonary embolism using only objective clinical variables. It assigns points for age 65 or older previous deep vein thrombosis or pulmonary embolism recent surgery or fracture active malignancy unilateral lower limb pain hemoptysis signs of d
Lights Criteria for Pleural Effusion Explanation and Clinical Context Lights Criteria is a well established diagnostic framework used to differentiate exudative pleural effusion from transudative pleural effusion based on biochemical comparison of pleural fluid and serum. Exudative effusion indicates increased capillary permeability usually due to inflammatory or malignant processes while transudative effusion occurs
Tidal Volume VT in liters Respiratory Rate RR in breaths per minute Explanation and Clinical Context Minute ventilation is the total amount of air moved in or out of the lungs in one minute. It is obtained by multiplying tidal volume with respiratory rate. This parameter reflects the effectiveness of pulmonary ventilation and is a key component of respiratory physiology. Normal values in healthy adults range between
Modified Asthma Predictive Index Explanation and Clinical Context The Modified Asthma Predictive Index is a validated clinical tool used to estimate the risk of developing persistent asthma in children who present with recurrent wheezing during early childhood. The index is designed to differentiate transient wheezing associated with viral illness from an evolving chronic airway disease pattern. The tool uses a combi
Pneumonia Severity Index PSI Explanation and Clinical Context The PSI is a clinical prediction rule that estimates mortality risk in adults with community acquired pneumonia. It integrates demographic factors comorbid conditions physical findings and laboratory and radiographic data. The total score categorizes patients into five risk groups that correspond to increasing severity and mortality. It assists clinicians
Age Height in cm Sex Select Male Female Explanation and Clinical Context Residual Lung Volume represents the amount of air that remains in the lungs after a maximal exhalation and reflects the mechanical properties of the respiratory system including elastic recoil and airway closure. A higher Residual Lung Volume may indicate air trapping caused by conditions such as chronic obstructive pulmonary disease asthma or s