The WOCA negative pressure wound therapy device designed for low resource settings

Abstract

Negative Pressure Wound Therapy (NPWT) is a treatment that promotes healing of chronic wounds. Despite high prevalence of chronic wounds in Low- and Middle-Income Countries (LMICs), NPWT devices are not available nor affordable. This study aims to improve chronic wound care in LMICs by presenting the Wound Care (WOCA) system, designed for building, testing and use in LMICs. Design requirements were formulated using input from literature, ISO standards, and wound care experts. The WOCA design was developed to provide safe, portable, user-friendly and affordable NPWT to patients in LMICs. The design features an adjustable operating pressure ranging from -75 to -125 mmHg, a battery for portability, a 300 ml canister, overflow protection, and system state alarms. An Arduino controls the pressure and monitors the system state. Three prototypes were developed and built in Nepal, and their performance was evaluated. Pressure control was 125 ± 10 % mmHg, internal leakage was 7.5 ± 4.3 mmHg/min, reserve capacity was 189 ± 16.9 ml/min, and overflow protection and alarm systems were effectively working. Prototype cost was approximately 280 USD. The WOCA demonstrates to be a locally producible NPWT device that can safely generate a stable vacuum. Future research will include clinical trials situated in LMICs.

Keywords: Low-cost; Low-resource setting; Medical device; Negative pressure wound therapy; Vacuum-assisted closure therapy; Wound care.

Graphical abstract

Fig. 1

Setup of the converted aquarium pump (AquaVAC) used in Green Pastures Hospital. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

Conceptual design of the WOCA Pump .

Fig. 3

The WOCA Pump consists of a vacuum pump, bacterial filter, and canister.

Fig. 4

System Block Diagram of WOCA Pump.

Fig. 5

Schematic of the electrical circuit in the WOCA Vacuum Pump.

Fig. 6

Flowchart of Arduino control software of the WOCA Pump.

Fig. 7

Testing of the WOCA prototype in Nepal. (Left) Pressure and leak tests with a gas flow analyzer. (Right) Packaging of the prototype for transportation test.

Fig. 8

3D printed parts of the WOCA Vacuum Pump.

Fig. 9

Connection terminals placements for electrical components. (A) Pressure sensor (B) LEDs (C) DC power connector (D) Potentiometer.

Fig. 10

(A) Heat shrinks applied to protect solder. (B) Pin terminals connections. (C) A display of all components soldered with wires.

Fig. 11

Schematic of the connections on the prototype board.

Fig. 12

Instructions for assembling components on the Hole Grid.

Fig. 13

(Left) Motor Driver with jumper pins removed. (Right) Components assembled on the Hole Grid.

Fig. 14

Instructions for installing the Pressure Gauge on the Front Housing.

Fig. 15

(Left) Foam Tape applied to the housing for the vacuum pump. (Right) Components assembled on the Front Housing.

Fig. 16

Instructions for assembling components to the Front Housing.

Fig. 17

Instructions for connecting the tubing for the WOCA vacuum pump.

Fig. 18

Components in the WOCA vacuum pump with all the tubing connected.

Fig. 19

(A) Split wire for the power connections. (B) DC Adapters for the Lithium Battery. (C) Grooves on the Hole Grid and the hole on the Front Housing to protect the wire connections from clipping.

Fig. 20

Microcontroller (Arduino Nano) connected to a computer with a USB wire.

Fig. 21

Instructions to assemble Back Housing and Canister Holder.

Fig. 22

Completed WOCA Vacuum Pump.

Fig. 23

3D printed parts of the WOCA Canister.

Fig. 24

Instructions for assembling the WOCA canister lid.

Fig. 25

(A) Components of WOCA Canister. (B) WOCA Canister after assembly.

Fig. 26

Connections and controls of the WOCA Pump System.

Fig. 27

Definition of different LEDs and alarm states in the WOCA Vacuum Pump. Rotate the control knob clockwise to adjust target pressure. Pressure range from 75 to 125 mmHg.

Fig. 28

Setup for leakage test of the WOCA Pump.

Fig. 29

Recorded pressure values from the sensor in the WOCA Pump pressure control test.

Fig. 30

Flowchart for troubleshooting the WOCA.