Lightweight Tourniquet with Nested Strap and Windlass

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Solution Overview

Problem

Conventional lightweight tourniquets are insufficiently strong and prone to unraveling under pressure, especially when used on large limbs, such as those of obese individuals, due to the lack of mechanical advantage to effectively occlude arterial blood flow.

Innovation Solution

A tourniquet design featuring an inner strap and an outer strap with a buckle, where the inner strap extends through a windlass and is knotted around the buckle, distributing tension more evenly through multiple rows of stitching and using hook and loop fasteners for secure attachment, providing mechanical strength and preventing slippage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a lightweight tourniquet is designed without a windlass or twist stick, then the device weight is reduced and ease of operation is improved, but the tourniquet becomes insufficiently strong to occlude arterial blood flow and can unravel under pressure

Engineering Contradiction:

Improvetourniquet weightVSAvoidtourniquet strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The tourniquet is divided into two separate straps: an inner strap that provides the constricting function and an outer strap that provides structural support and strength. This segmentation allows each strap to be optimized for its specific function while maintaining overall lightweight design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner strap is nested within the outer strap, with the inner strap positioned inside the tubular structure formed by the outer strap. This nesting arrangement allows the weaker inner strap to provide the necessary constriction while the stronger outer strap prevents unraveling and provides structural integrity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Device complexity

If material is merely wrapped tightly around a limb without a windlass, then the device complexity is reduced and ease of operation is improved, but only venous flow is occluded while arterial flow continues

Engineering Contradiction:

Improvetourniquet complexityVSAvoidarterial flow occlusion

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The outer strap acts as an intermediary structural element that reinforces the inner strap. While the inner strap applies the constriction force, the outer strap serves as a mediator that prevents the inner strap from unraveling under the high pressures required to stop arterial flow, thereby ensuring reliable arterial occlusion without requiring a complex windlass mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If a single strap is used for the tourniquet, then the device complexity is reduced and manufacturing is simplified, but the strap cannot maintain structural integrity under high pressure on large limbs

Engineering Contradiction:

Improvetourniquet manufacturingVSAvoidtourniquet structural integrity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The tourniquet is segmented into an inner strap and an outer strap with different functional requirements. The outer strap is constructed as a tubular structure with multiple rows of stitching to provide structural integrity and resistance to unraveling, while the inner strap focuses on providing the constricting force. This segmentation allows each component to be manufactured independently with optimized characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tourniquet utilizes composite construction by combining two different strap structures: a simple inner strap for constriction and a reinforced tubular outer strap for structural support. This composite approach allows the device to maintain structural integrity under high pressure while remaining relatively simple to manufacture.

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 design effectively occludes arterial blood flow while maintaining structural integrity, preventing hemorrhaging and blood loss, even on larger limbs, by distributing tension more evenly and securely attaching the inner strap to the outer strap.

Implementation Method 1

A windlass or twist stick is conventionally used to tighten the constricting band or material to stop the arterial flow

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 2

using hook and loop fasteners for secure attachment

Methodology Applied

Scientific EffectHook and loop fastening: Velcro

Data Source

PatentUS11684373B2Lightweight tourniquet

Publication Date: 2023.06.27 PARSONS DEREK MR

AI summary

A tourniquet is described that includes an outer strap that runs from a first end to a second end having a buckle. An inner strap is routed within the outer strap over a portion of its length and runs through a windlass, which is used to tighten the tourniquet. The inner strap is secured to the outer strap at a position spaced away from the first end of the outer strap and is also secured to the buckle.