Sitting Pressure and Perfusion of Buttock Skin in Paraplegic and Tetraplegic Patients, and in Healthy Subjects: A Comparative Study

Abstract

The distribution of sitting pressure and ability to respond with reactive hyperaemia were studied in a group of paraplegic and tetraplegic patients (n = 8) with spinal cord lesions and healthy controls (n = 10) using a pressure sensitive plate and laser Doppler perfusion imager. The results show that the mean sitting pressure of the patients was 9.9 N/cm2 (left) and 11.7 N/cm2 (right) compared with 3.5 N/cm2 (left) and 3.6 N/cm2 (right) in controls. The differences were significant on both the left (p < 0.01) and right (p < 0.05) sides. The maximum pressure in patients was 42.9 N/cm2 (left) and 48.7 N/cm2 (right), and in controls 12.0 N/cm2 (left) and 12.9 (right) (p < 0.01). Both groups showed a reduction in skin perfusion in the seat area during sitting compared with unloaded resting, and in the controls it was significantly increased (p < 0.001 on both sides) during the reactive hyperaemic phase immediately after sitting. Compared with the preload values, the patients showed a similar but slightly weaker picture significant on the right side (p < 0.05), but not on the left. The hyperaemia was not uniformly distributed, but occurred where the pressure was greater than 2 N/cm2. There was no correlation between the amount of reactive hyperaemia and absolute values of sitting pressures. We conclude that tetraplegic and paraplegic patients have significantly higher sitting pressures than normal controls, and that the hyperaemic response in the buttock region in the upright position after pressure load is slightly weaker in the patients, which could be of importance for the development of decubitus ulcers.

Measuring seating pressure, area, and asymmetry in persons with spinal cord injury

“…This again corresponds to the findings of Aissaoui et al [1], who reported SCI subjects as having a maximum pressure of 199-212 mmHg, equivalent to 271-288 g/cm 2 , in a standard chair with a flat-foam cushion. The pressure on the hard surface of 1,205 g/cm 2 , equivalent to 886 mmHg, also correlates with results from Thorfinn et al [16], who reported a maximum pressure of 11.7 N/cm 2 , equivalent to 877 mmHg or 1,192 g/cm 2 , in SCI subjects sitting on a glass plate.…”

“…Other studies have compared and determined higher seating pressures in persons with SCI than in able-bodied subjects [16]. A recent study has derived an algorithm to define the area of highest pressure under the ischial tuberosity (IT) region and have shown that the IT weight-bearing area in subjects with SCI is half that of able-bodied controls [1].…”

Hyperaemic changes in forearm skin perfusion and RBC concentration after increasing occlusion times

“…In most animal and human studies, longer occlusion times have been found to result in responses that are larger in magnitude. However, it has also been suggested that the hyperaemic response reaches a maximum with 5 minutes of occlusion (Faizi et al, 2009;Thorfinn et al, 2002;Thorfinn et al, 2007;Yvonne-Tee et al, 2008). For clinical assessment of vascular function, it has been suggested that 3 minutes (with LDF) or 5 minutes (with plethysmography) is the optimal occlusion duration, as those seem to result in maximal hyperaemic responses (Faizi et al, 2009;Yvonne-Tee et al, 2008).…”

A survey of protective cushion usage in individuals with spinal cord injury while traveling in a motor vehicle and on a commercial airliner

“…It has been estimated that 50-80% of persons with SCI will, at some time after their injury, develop a pressure ulcer. [1][2][3][4][5] Pressure ulcers may interfere with mobility and community reintegration, can lead to a loss of independence, more serious medical complications, and result in profound economic and psychosocial consequences that may negatively impact quality of life. 1,6 Pressure ulcers most commonly occur at the ischial tuberosities (IT) due to the pressures associated with sitting, followed by the sacrum, in those with chronic SCI.…”

“…1,6 Pressure ulcers most commonly occur at the ischial tuberosities (IT) due to the pressures associated with sitting, followed by the sacrum, in those with chronic SCI. [1][2][3] A major focus of rehabilitation healthcare providers who serve this population is to educate the patient (and caregivers) to prevent the development of pressure ulcers. This includes education regarding etiology, risk factors, and proper positioning; prescribing appropriate equipment including pressure relieving cushions; and performance of timely and effective weight shifting.…”