Physiological responses to the early mobilisation of the intubated, ventilated abdominal surgery patient

The aim of this study was to investigate the effects of mobilisation on respiratory and haemodynamic variables in the intubated, ventilated abdominal surgical patient. Mobilisation was defined as the progression of activity from supine, to sitting over the edge of the bed, standing, walking on the spot for one minute, sitting out of bed initially, and sitting out of bed for 20 minutes. Seventeen patients with age (mean +/- SD) 71.4 +/- 7.1 years satisfied inclusion criteria. Respiratory and haemodynamic parameters were measured in each of the above positions and compared with supine. In the 15 subjects who completed the protocol, standing resulted in significant increases in minute ventilation (V-E) from 15.1 +/- 3.1 l/min in supine to 21.3 +/- 3.6 l/min in standing (p < 0.001). The increase in V-E in standing was achieved by significant increases in tidal volume (V-T) from 712.7 +/- 172.8 ml to 883.4 +/- 196.3 ml (p = 0.008) and in respiratory rate (f(R)) from 21.4 +/- 5.0 breaths/min to 24.9 +/- 4.5 breaths/min (p = 0.03). No further increases were observed in these parameters beyond standing when activity was progressed to walking on the spot for one minute. When supine values were compared with walking on the spot for one minute, inspiratory flow rates (V-T/T-I) increased significantly from 683 +/- 131.8 ml/sec to 985.1 +/- 162.3 ml/sec (p = 0.001) with significant increases in rib cage displacement (p = 0.001) and no significant increase in abdominal displacement (p = 0.23). Arterial blood gases displayed no improvements following mobilisation. Changes in V-T, f(R), and V-E were largely due to positional changes when moving from supine to standing.