Carboxymethylcellulose Foam Hemostasis and Resorption Control

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Solution Overview

Problem

Current bioresorbable packing and stents lack effective hemostatic properties and controlled resorption times, particularly for post-operative and drug delivery applications, where they are needed to manage bleeding and prevent tissue adhesion.

Innovation Solution

A flexible bioresorbable foam made from 100% carboxymethylcellulose with dehydrothermal crosslinking and lyophilization processes, providing hemostatic properties and a controlled in-vivo residence time of about 14 days, suitable for various medical uses including nasal packing, sinus stents, and drug delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bioresorbable packing materials (hyaluronic acid, polysaccharides) are used, then biocompatibility and tissue compatibility are improved, but hemostatic properties are insufficient

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidlack of hemostatic properties
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent combines carboxymethylcellulose (CMC) with collagen and/or fibrin in a foam structure to create a composite material that simultaneously provides biocompatibility, hemostatic properties, and controlled resorption. The CMC matrix offers biocompatibility and resorption control, while the collagen/fibrin components provide hemostatic activity through thrombin generation and platelet activation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The foam structure provides a porous network that facilitates hemostasis through thrombin generation and platelet aggregation within the void spaces, while maintaining controlled resorption. The porosity allows for fluid penetration and cellular infiltration, enabling the material to perform multiple functions simultaneously.

Inventive Principle:
Principle #31Porous materials

2Duration of action of stationary object

If crosslinked HA materials are used, then insolubility and longer in-vivo residence time are improved, but hemostatic properties remain insufficient

Engineering Contradiction:
Improvein-vivo residence timeVSAvoidinsufficient hemostatic properties
Core Design Contradiction:
Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent creates a composite where crosslinked CMC provides extended residence time (14 days), while incorporated collagen and fibrin components maintain hemostatic activity throughout the resorption period. The synergistic combination ensures both prolonged presence and continuous functional performance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The foam structure maintains continuous hemostatic activity throughout its 14-day residence time through sustained thrombin generation and platelet activation. The porous network continuously facilitates these processes from insertion until complete resorption, ensuring uninterrupted useful action.

Inventive Principle:
Principle #20Continuity of useful action

3Object-generated harmful factors

If collagen is used as bioresorbable material, then hemostatic properties are improved, but controlled resorption time is insufficient

Engineering Contradiction:
Improvehemostatic propertiesVSAvoidresorption time
Core Design Contradiction:
Object-generated harmful factorsVSDuration of action of stationary object

Solution Approach 1:

The patent combines collagen (providing hemostasis) with CMC (providing controlled resorption) in a foam matrix. The CMC component regulates the resorption rate to achieve the desired 14-day timeline, while collagen maintains hemostatic functionality throughout this period through thrombin generation and platelet activation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the resorption parameters of collagen by incorporating it into a CMC foam matrix, which controls the degradation rate and extends the residence time to 14 days. This parameter change allows the material to maintain hemostatic properties for an extended period rather than rapid resorption.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If flexible foam is made from carboxymethylcellulose, then ease of handling and contouring are improved, but hemostatic properties must be demonstrated

Engineering Contradiction:
Improveease of handlingVSAvoidneed to demonstrate hemostatic properties
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent creates a flexible CMC-based foam composite incorporating collagen and/or fibrin that maintains ease of handling and contouring while demonstrating hemostatic properties through thrombin generation and platelet aggregation. The flexible foam structure allows for easy manipulation during surgery, and the composite composition ensures functional hemostatic performance.

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The foam effectively controls bleeding, prevents adhesion, and provides a controlled resorption time, making it suitable for diverse medical applications while being easy to handle and contour within body cavities.

Implementation Method 1

dehydrothermal crosslinking and lyophilization processes

Methodology Applied
Scientific EffectDehydrothermal crosslinking:

Implementation Method 2

dehydrothermal crosslinking and lyophilization processes

Methodology Applied
Scientific EffectLyophilization: Freeze Drying

Implementation Method 3

flexible bioresorbable foam... providing hemostatic properties and a controlled in-vivo residence time of about 14 days

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3178500B1Flexible bioresorbable hemostatic packing and stent
Publication Date: 2020.04.01 MEDTRONIC XOMED INC

AI summary

A method of making a flexible bioresorbable foam comprising the steps of: a) providing a carboxymethylcellulose component, b) mixing the carboxymethylcellulose component with water to form a suspension, c) freezing and lyophilizing the carboxymethylcellulose at 0 degrees C or below, and d) crosslinking and sterilizing the carboxymethylcellulose with use of gamma and ebeam irradiation past the point of sterilization such that the foam has an in-vivo residence time between 3 and 6 days.