Predicting normal lung function in patients with childhood spinal cord injury

A prospective observational study.

To compare the height and arm span measurements in childhood spinal cord injured (SCI) people and examine the subsequent effect on calculating the predicted lung function using standard formulae and to discuss which of the two measurements is the most appropriate to use in these formulae.

National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, UK.

A total of 12 children had lung function tests performed and at the same time had height and armspan measured. The predicted lung function was calculated twice; once using height and then using arm span and compared. The actual lung function test results were expressed as percentage of the two predicted values, respectively, and compared.

The difference between the mean height (1499 mm) and arm span (1649 mm) measurements was significant (P<0.001). In all cases, the arm span measurement was greater than the height. The two predicted lung function values (one calculated using height and the other armspan) were significantly different (P<0.001). When lung function test results were expressed as percentage of the two predicted values they gave a very different interpretation of the results. The actual performance was much lower than the predicted values if arm span, rather than height, was used in prediction equations.

In childhood SCI, the difference in height and arm span is significant. This affects the predicted lung function values significantly and thus changes the interpretation of the lung function test results. The most appropriate measurement to use in prediction equations (height or arm span) in these subjects is yet to be decided.