Wound treatment technique applying Negative Pressure Wound Therapy (NPWT) and the innovative tools of the MINI-VACUUM family
The prolonged sub-atmospheric pressure system is a relatively recent method, which finds application in the treatment of open, acute and chronic wounds, which are particularly difficult to treat with conventional strategies, especially when they are infected. It is identified with different acronyms: TNP (Topical Negative Pressure), SAP (Sub-Atmospheric Pressure), VST (Vacuum Sealing Technique), SSS (Sealed Surface Wound Suction), NPWT (Negative Pressure Wound Therapy) which is currently the acronym most used in scientific literature.
The working principle of NPWT is quite simple and numerous scientific works have described the use of this method in the treatment of various types of wounds, including extensive skinning wounds, infected sternotomies and various soft tissue lesions subsequently treated by surgical suture, grafts or reconstructive surgery. The use of the suction system has also been proposed in the treatment of burns and in association with the packaging of skin grafts, especially in those areas of the body that have irregular and deep contours, such as the perineum, the upper limb and the axillary cavity. In these circumstances, the vacuum helps to keep the graft adhered to the plane of the lesion, preventing the filtration of exudates from causing instability of the tissue.
Currently there are numerous systems on the market specifically built for the realization of the dressing at sub-atmospheric pressure, starting from the first introduction on the US market in 1995. These devices consist of a suction system (pump) capable of providing controlled levels of continuous sub-atmospheric pressure or intermittent, between -25 and -200 mmHg. There are also portable versions powered by batteries and intended for outpatients.
Negative pressure is transferred from the vacuum pump to the injury site through a tube that contracts a polyurethane foam dressing, with open and cross-linked pores, of about 1 mm in diameter. Interposed in the circuit there is a tank for the collection of secretions, with a volume of 0.5-1L.
At the moment, the systems on the market do not have the necessary diffusion for cost reasons, while the indication for the use of the NPWT is in great expansion. In fact, many wounds that in the past would not have indicated an indication for this treatment are now considered differently: for example, NPWT would have proved capable of reducing the incidence of surgical wound infections (so-called surgical site infections) if applied early, i.e. from the operating room at the end of the intervention. In addition, this type of NPWT application reduces postoperative costs since it can be left in situ until the patient is discharged, replacing the traditional daily wound dressing.
Overall, therefore, additional devices are increasingly needed to make the NPWT, and the limitation of use lies in the costs of the machinery.
List of diseases treatable with vacuum therapy:
- Open wounds
- Infected wounds
- Venous ulcers
- Skin grafts
- Open abdomen
- Intestinal fistulas
- Infections of prostheses for hernias
- Perineal perianal abscesses
- Foot gangrene
- Fourier’s gangrene
- Open osteomyelitis
- Limb abscesses
- Necrotizing fasciitis
- Prevention of wound infections
Drastic reduction in the cost of the equipment
The MINI-VACUUM MV01 device has the purpose of drastically reducing costs
of the equipment, using a construction technique using the centralized vacuum system
. The device in question consists in a system of solenoid valves controlled by a microprocessor which are capable of regulating the vacuum level, starting from the high vacuum of the centralized system, up to the levels required by this type of therapy and maintaining them unchanged over time, within a modest predefined and acceptable interval. With this system, costs are considerably reduced since the electric vacuum pump and all its control and operating accessories are not required. Wound dressing, polyurethane sponges, adhesive films for air tightness, connecting pipes and secretion collector remain substantially identical to the devices used so far.
MINI-VACUUM MV01 device is characterized by simplicity and economy. It exploits in an original way
the presence of the vacuum systems located in hospital rooms. Usually these sockets are used to connect a pressure reducer (vacuum) through which to aspirate the patient’s secretions or keep the reservoirs of the thoracic aspiration in depression when necessary, less frequently than the gastric nose tube. Overall, the use of the vacuum is infrequent, much less frequent, for example, of the use of the oxygen supply which represents the other centralized system present in each bed head.
The device maintains all basic characteristics, but performs the vacuum reduction and its control electronically by controlling the solenoid valves. This system uses mini valves, made of anti-corrosion plastic material and therefore resistant to humidity present in the intake; they were carried out taking into account the need for many operating cycles per minute without reducing performance; with very low noise characteristics so that they can be applied to an object that is located near the patient. Furthermore, the vacuum level is regulated by frequency modulation of the opening, closing of the valves rather than by using the degree of opening.
This mechanics is enslaved to a control logic elaborated and located in a microprocessor which performs numerous functions. First of all, it manages a small screen downstream of the user interface, where the desired pressure can be set with an accuracy of 10%, the switching on and off of the equipment, as well as the management of safety alarms. The latter consist of a control of the level of depression in the centralized line (ie upstream of the equipment) and in the downstream line towards the patient. The most interesting feature of this system is the stability it guarantees at the working pressure established by the user, unlike the usual reducers in use where the depression is subject to a drift depending on numerous factors including the flow of the sucked air factors that are not in the user’s practical control possibilities. Otherwise, this system maintains the desired level of depression in a wide range of air flow.
Finally, the manufacturing methods of the device have privileged the possibility of connecting it directly to the vacuum outlet with maximum simplicity, the same as the current vacuum reducers. In order to allow the simultaneous use of the vacuum system, there is a lateral outlet from the device to which to apply a possible tube for the suction of the secretions.
In addition to the application to the NPWT, the MINI-VACUUM SMD01 can represent an interesting innovation for the application to the thoracic drainage for pneumothorax. In fact, the current system provides a plastic container containing a “water valve” to guarantee those low vacuum levels – around 20 cm of water, corresponding to 15 mm of mercury – that are applied to the pleural cavity through thoracic drainage . The current system – which provides for the vacuum of the centralized system moderated by the vacuum regulator to be exercised in the container with the water valve – is largely inaccurate precisely because of the lack of stability of the regulated pressure. The result is that of an excessive gurgling of the gas bubbles in the container, with noise, evaporation of the water and a large imprecision of the desired depression in the container precisely because the large (and excessive) passage of gas in it does not allow the air to gurgle to stabilize the pressure level which tends to be excessive (excess depression).