Keywords:
Performed at one institution, Experimental, Not applicable, Tissue characterisation, Developmental disease, Biological effects, Laboratory tests, Equipment, Computer Applications-3D, Digital radiography, CT, Conventional radiography, Soft tissues / Skin, Radiographers, Anatomy, Patient Care
Authors:
N. M. T. Alresheedi1, S. Al-Murshedi2, A. K. Tootell1, J.-A. webb1, L. A. Walton1, P. Hogg1; 1Salford/UK, 2Karbala/IQ
DOI:
10.26044/ecr2020/C-05216
Results
Table 1 shows the average (and SD) PPVs for 3D phantom and humans. For head, sacrum and heels, average 3D phantom and human PPVs shows excellent positive correlation across all weights (R2=0.993, 0.9973 and 0.9958, respectively).
Table 1: Peak Pressure Values for phantom and humans.
|
Categories
|
Human volunteer data (average and SD)
|
3D phantom data (average and SD)
|
Weights for 3D phantom (kg)
|
Head
|
Sacrum
|
Heels
|
Head
|
Sacrum
|
Heels
|
Head
|
Sacrum
|
Heels
|
Maximum
|
47.3±1.18
|
54.6±1.24
|
56±3.49
|
46.6±62.7
|
57.4±2.41
|
55.4±1.38
|
6
|
37
|
3
|
Third quartile
|
38.7±2.02
|
44.1±2.67
|
34.7±2.
|
39.1±2.33
|
47.1±1.75
|
37.6±1.93
|
3
|
30
|
1.3
|
Mean
|
33.6±1.66
|
39.6±1
|
29.8±1.25
|
35.3±2.08
|
41.5±2.52
|
31±2.60
|
2.5
|
24
|
1
|
First quartile
|
30±1.77
|
34.3±2.4
|
22.5±2.21
|
30.3±2.31
|
35.9±1.81
|
24.9±1.66
|
2
|
21
|
0.8
|
Minimum
|
22.1±1.32
|
25.4±2.61
|
18.8±0.50
|
22.5±1.34
|
24.9±1.1
|
22.5±1.67
|
1.5
|
10
|
0.3
|
Pressure Profiles and PPV Ratio
Multiple profile graphs were created, using phantom and volunteer XSensor interface pressure data, from pelvis, head and heels for the 5 weight categories, so comparisons could be made between human and phantom pelvis. An example of this can be seen in Graph 1. Graph 1A shows interface pressures images of a human (above) and phantom (below). For human the whole-body outline is seen, whereas for phantom only jeopardy areas are seen (head, pelvis and heels). Graph 1B shows example line profiles of interface pressure for head (human, above; phantom, below); Graph 1C shows example line profiles of interface pressure for pelvis (human, above; phantom, below). Graph 1D shows example line profiles of interface pressure for heels (human, above; phantom, below). Visual comparison of all human/phantom profiles shows reasonable similarity between them; this is confirmed statistically using Paired T-Test, where all the line profile data shows good similarity for the three jeopardy areas for the 5 weight categories (p > 0.05).
Interface Pressure Ratio
Using phantom data, a novel Interface Pressure Ratio (IPR) has been developed to indicate mattress interface pressure redistribution efficiency. IPR serves as a simple indicator to compare between mattresses and for the same mattress over time. IPR uses phantom PPVs from head, sacrum and heels when a ‘mattress is used’ (experimental condition) against ‘no mattress’ (control condition). IPR formula is indicated below:
PPV when Mattress is used / PPV for no mattress
Where IPR values varies between 0 and 1. ‘1’ implies the mattress has the same interface pressure distribution properties as a hard surface (e.g. X-ray table surface). As the ratio approaches ‘0’, the interface pressure redistribution properties of the mattress improve. Table 2 illustrates the IPRs from a 15-year-old X-ray table mattress that is in current clinical use. For the five weight categories, the IPR indicates the mattress interface pressure redistribution properties are similar to the X-ray table itself (i.e. approaching ‘1’, which is very poor).
Table 2
|
|
Peak Pressure Index mmHg
|
Pressure Ratio
|
Value
|
Head
|
Sacrum
|
Heels
|
Head
|
Sacrum
|
Heels
|
Maximum
|
88.5
|
110.7
|
97.3
|
0.93
|
0.85
|
0.95
|
Third quartile
|
68.9
|
93.4
|
78.1
|
0.92
|
0.78
|
0.90
|
Mean
|
60.6
|
79.2
|
70.2
|
0.85
|
0.78
|
0.86
|
First quartile
|
55.4
|
62.5
|
53.9
|
0.84
|
0.70
|
0.94
|
Minimum
|
50.1
|
47.5
|
35.1
|
0.83
|
0.93
|
0.92
|