Wheelchair tilt-in-space and recline function:  influence on seat interface pressure and ischial blood flow in an aged population

Rhona Moot’s free paper presentation at PMG Conference 2019 reported on a study about the effect of tilt-in-space and recline on sitting, interface pressure, ischial blood flow, and on the relationship between them.

It was of particular interest to me because, working in a community rehabilitation setting for many years, I was aware of the importance of using position to manage pressure. The presentation highlighted how vague my knowledge had been about precisely what alters pressure distribution. 

In my new role in the wheelchair service I have prescribed wheelchairs with tilt-in-space functionality, and I regularly encourage the use of tilt-in-space as a way of changing a client's position and gravitational forces to reduce interface pressure.  However, having heard this presentation by Rhona (pictured), I realise that it’s not just about relieving the pressure, but about the length of time it takes for blood flow to return to the areas that have been under pressure.

Another common problem that Rhona mentioned is the difficulty in ensuring that those adjusting the position of the wheelchair know the difference between recline and tilt-in-space, and the impact each function has on the individual wheelchair user.  I have come up against this difficulty frequently in daily practice.  As several of the clients I see are dependent on others for change of position, I often discuss pressure management with carers/family members, and it seems most people find it difficult to understand the difference between recline and tilt-in-space. 

Due to the problem of people not understanding the difference between the two levers on the handles (green and yellow on the Rea Azalea) what tends to happen is that they use a ‘bit of both’; the patient’s posture is affected as a result, usually by them sliding forward in the wheelchair because excess recline has been set.  For this reason I often ‘lock off’ the recline at a point that is effective for the client, and leave the carers to adjust tilt-in-space only.

What was clear from Rhona’s paper is that both tilt-in-space and recline affect interface pressure, which led me to wonder whether I am doing a disservice to my patients by locking off recline.  However, it is common knowledge that by adjusting recline alone, the risk of shear is higher (Hobson, 1992).  This, coupled with a potential adverse effect on posture (Tierney, 2019), leads me to reason that, unless a patient has the same person adjusting the chair at all times (someone who is aware of how to use the two functions effectively), then locking off the recline is an appropriate compromise to reduce risk to the patient.

Another interesting point is that an increase in blood flow to the tissues is only seen at larger angles of tilt and recline.  Therefore to assist with cell healing, large angles of tilt and recline are required.  This is often difficult to achieve because recline is locked off for many patients and, because most prefer to remain upright for activities, they resist using larger angles of tilt.  Rhona compared the impact of using small and large angles:

• small angles of tilt and recline reduce mean pressures; there is no increase in blood flow, but the person finds it easier to be involved in daily activities
• larger angles of tilt and recline reduce mean pressures; there is an increase in blood flow, but it is much harder for the patient to be functional in this position

This presentation has led our therapy team to review practice when we issue chairs with tilt and recline functions.  We are now much more aware of how we educate carers, and how we prescribe the use of tilt and recline, and are now issuing tilt gauges as standard to help carers set appropriate positions.  We are also providing verbal and written information on why we have set recline to a particular level, why certain levels of tilt are required, what activities need to have a different angle, and when to adjust back to the prescribed tilt angle.  We have designed small posters to show the difference between recline and tilt, and have produced small laminated signs to be issued with relevant wheelchairs showing at-a-glance the effects of both recline and tilt.

The aim with these changes in our practice is to help carers/family members understand why recline and tilt are used, the difference between the two, and to reduce postural and pressure risk to our patients. 

References

Hobson, D.A., Comparative effects of posture on pressure and shear at the body-seat interface. J Rehabil Res Dev, 1992. 29(4): p. 21-31.

Tierney, M., 2019. What is the difference in back angle recline and tilt in space?. [Online] Available at: http://blog.seatingmatters.com/faq-what-is-the-difference-in-recline-and-tilt-in-space [Accessed 11 September 2019].

Members of PMG can view Rhona's presentation by clicking here.