GB2430876A

GB2430876A - Alternating pressure mattress

Info

Publication number: GB2430876A
Application number: GB0520139A
Authority: GB
Inventors: Colin Davies
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-10-04
Filing date: 2005-10-04
Publication date: 2007-04-11
Also published as: GB0520139D0

Abstract

In an alternating mattress alternate cells are inflated before supporting cells are deflated to keep the patient stationary. Lack of movement in the patient avoids motion sickness, makes sleeping easier and is better where there are spinal injuries. The device keeps the patient stationary by actively monitoring pressures within the inflatable cells. The device inflates cells in sequence and monitors the inflated cells to an accurate pressure before deflation of the next cell occurs. This process works with any pressures, timings or sequences that are set via the control program. The use of hospital clean air and vacuum can be used in conjunction with the above device or used independently to replace any pump within existing alternating pressure devices. The use of clean air will avoid any contaminant or infectious element within the ward atmosphere from entering the device. The use of vacuum to expel the air will avoid the release of any contaminant already existing within the equipment or mattress into the atmosphere. If desired, clean air can be used without vacuum. In this case, the clean air can be allowed to escape through the top layer of the mattress below the patient to act as cooling for the patient. This air can have vapours, moisture or medicine added.

Description

DEVELOPING THE NEXT STEP

\Vith the original prototype, the most expensive iteni is the actual pump module at a cost of jJ3OO This expense can be saved if the patient air supply system figure 1.11 is used to replace the pump.

This system is a network of pipes providing oxygen, clean air and a VaCUUm to each hospitI bed.

The clean air system is kept at a constant pressure of 4 bar, the required maximum pressure required for an alternating pressure system is 0.13 bar.

Design Overview The key elentents of the prototype system were identified as the mattress air cell, air supply, the inlet and outlet valves, pressure transducer, and the solenoid programmable Pie controller, Figure 1.12 shows a simplified block diagram of how these elements interrelate in the electronic and pneumatic systems within the design.

An air pump and pressure regulator valve were required to supply the air for inflation, while ensuring the air pressure did not exceed a pre-set maximum. The pressure in each air cell within the mattress was to be controlled using solenoid valves to regulate the airflow into the cells. However with this new design the out let valve will only actuate on the deflate cycle. This is because with the plc speed, it is thought to be unnecessary, as the pressure is checked every I second. Also any patient movement will not cause the solenoid to active thereby solving any oscillations of the system previously encountered.

*. Pressure transducers would be used to provide the necessary feedback data, as in the previous system, but this reading will now be measured against a reference voltage, using a comparator with logic output * * levels. These levels can be easily set up with a potentiometer to varying the reference voltages depending on required patient charactenstics. These logic levels from the comparators are then read by * the pie, which will operate the required solenoids. A more detailed view of the system is outlined in Figure 1.14:

I **SI*

* S Circuit Design The main part of this new prototype is the plc control, this will check the outputs from the * comparators which have been set up to the patient reqwrements Figure 1. 15. From the outputs alogic level is obtained the pic will then operate solenoids by means of a logic output to turn the controlling Mosfets to the required state. The pic will also monitor any alarm conditions and if connected will lock down all the solenoids and sound the audible alann.

-LW-

Claims

1. An alternating pressure mattress controlled by programmable settings and operated in a manner which allows the patient to be kept stationary.

2. A mattress as claimed in Claim I utilising hospital clean air system for inflation of the air cells and hospital vacuum for deflation of the air cells.