Measurement of abdominal wall compliance in normal subjects and tetraplegic patients.

Abstract

On inspiration descent of the diaphragm is opposed by the passive properties of the abdominal wall, the tone of its muscles, and the inertia of the abdominal contents. As a result, intra-abdominal pressure rises and promotes rib cage expansion. In patients with high spinal injury the diaphragm is the most important muscle of inspiration and abdominal wall displacement is more evident than in normal subjects. Abdominal wall compliance has been measured by relating gastric pressure to abdominal wall displacement, which was determined by means of an optical contour mapping system. Six normal subjects and six tetraplegic patients were studied in the supine posture, during passive expiration from total lung capacity to functional residual capacity. Over this lung volume range the normal subjects partitioned an average of 31% of expired volume to the abdominal compartment, while the corresponding average figure in the patients was 77% of expired volume. Since the range of gastric pressure was similar in the two groups, it is concluded that abdominal wall compliance is greater in tetraplegic patients. This high compliance could have a detrimental effect on lower rib cage expansion.Many investigators have noted that the abdominal wall moves more during breathing in tetraplegic patients than in normal subjects. Bergofsky' and Mortola and Sant Ambrogio2 have suggested that it does so because the rib cage is fixed or moves paradoxically. Danon etal3 suggested that paralysis and disuse atrophy of respiratory muscles may disturb the partitioning of compliance between rib cage and abdomen. This paper describes a study of the distensibility of the abdominal wall during a relaxed expiration from total lung capacity (TLC) to functional residual capacity (FRC) in normal subjects and patients with tetraplegia. It was conducted to test the idea that there would be easier abdominal wall displacement and therefore less resistance to descent of the diaphragn in tetraplegic patients than in healthy subjects. The gastric pressure/displaced volume characteristic of the anterolateral abdominal wall was used as a measure of distensibility.

Effect of abdominal binders on breathing in tetraplegic patients.

“…The differences between patients and healthy subjects agree with our previous findings of increased abdominal wall compliance in tetraplegia. 4 When normal subjects lie down, VC decreases by 7.5%.23 When tetraplegic patients who have been tilted head up lie down VC increases by about 45%.i6 If they lie down from the sitting position when the abdomen is splinted, VC rises by 28%. l6 In the present study the rises in VC when they lay down after the 700 tilt and after sitting were 49% and 28% respectively.…”

Abdominal binder use in people with spinal cord injuries: a systematic review and meta-analysis

“…The abdominal wall of patients with SCI, with no innervation of the abdominal muscles, has been found to be twice as compliant of those of healthy people. 38 Therefore, the abdomen is able to be bound with relative ease. With increasing time since SCI, patients may have adaptive migration of the abdominal contents and decreased anterior/posterior chest wall dimensions with the presentation of a 'quad belly'.…”

Respiratory Management in the Patient with Spinal Cord Injury

“…The loss of expiratory reserve volume can be explained by the denervation of the abdominal musculature and other muscles necessary for forced exhalation. Goldman et al [11] found that the abdominal wall in tetraplegic patients is twice as compliant as in normal subjects. There is recent evidence of the benefits of a semiseated position to the weaning process of patients dependent on a respirator [12] and the effect of the seated position on lung volume and oxygenation in acute respiratory distress syndrome [13].…”