Intrathoracic Volume Normalization Using Predicted Body Weight
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing patient monitoring apparatuses face errors in diagnosing intrathoracic volume compartments due to not considering a patient's actual body dimensions, leading to incorrect normalization of parameters like extravascular lung water, especially in corpulent or lean patients.
Innovation Solution
Normalization of intrathoracic volume parameters based on patient-specific biometric data using algorithms that categorize patients by factors such as gender, age, and body height, allowing for the selection of appropriate calculation paths and coefficients to account for individual differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If normalization is based on actual body weight, then simplicity of calculation is improved, but measurement precision deteriorates for corpulent or lean patients
Solution Approach 1:
The patent changes the normalization parameter from actual body weight to predicted body weight (PBW). PBW is calculated based on height and gender using established formulas (Devine formula for adults, Robinson formula for children), which accounts for ideal body composition rather than actual weight. This parameter change resolves the contradiction by providing accurate normalization for corpulent or lean patients while maintaining calculation simplicity through standardized formulas.
Solution Approach 2:
The patent introduces predicted body weight as an intermediary parameter between actual body weight and intrathoracic volume normalization. Instead of directly using actual weight for normalization, the system first calculates PBW based on height and gender, then uses PBW as the basis for normalizing intrathoracic volume parameters. This intermediary approach eliminates the errors caused by using actual weight in extreme body composition cases while maintaining a systematic and reproducible calculation process.
2Device complexity
If a single normalization method is used for all patients, then device complexity is reduced, but reliability deteriorates due to individual differences
Solution Approach 1:
The patent changes from a single normalization approach to a multi-parameter normalization system that considers height, gender, and age categories. Different normalization formulas are applied based on these parameters: Devine formula for adult males and females, Robinson formula for pediatric patients, and different height-based calculations for various gender groups. This parameter-based differentiation resolves the contradiction by providing reliable, individualized normalization while maintaining systematic simplicity through clear categorization rules.
Solution Approach 2:
The patent segments the patient population into different categories based on gender, age, and height parameters. The normalization method is then segmented accordingly: adult males use one formula, adult females use another, pediatric patients use yet another approach. This segmentation allows each group to receive the most appropriate normalization method for their physiological characteristics, improving diagnostic reliability while maintaining overall system simplicity through structured categorization.
Data Source
Figure 1
Figure 2
AI summary
The patient monitoring apparatus determines a parameter representing an intrathoracic volume compartment, such as extravascular lung water, and normalises the determined parameter on the basis of input biometric data, such as body height, using an algorithm selected from a plurality of algorithms depending on a category a patient is allocated to. Preferably, the parameter is normalised (S6) by dividing it by a predicted (ideal) body weight which is calculated from the patient's body height. A memory of the patient monitoring apparatus has stored therein a program for selectively executing one of several algorithms for determining a predicted weight (S51, S52, S53, S54, S55). Before determining normalised values, the operator is prompted to input height and gender of the patient and whether the patient is an adult or a pediatric patient (S1).