TABLE 3

Spearman's correlation coefficients between maximal inspiratory pressure and follow-up outcomes, and between duration of mechanical ventilation and inspiratory muscle outcomes

Variable3 months6 months
Maximal inspiratory pressure
 Diaphragm thickness0.312*0.273
 Diaphragm thickening ratio0.1800.308*
 6MWD0.657**0.622**
 6MWD % predicted0.380**0.284*
 Dyspnoea mMRC score−0.365**−0.379**
 Borg dyspnoea−0.097−0.015
 SGRQ−0.349*−0.277
Duration of mechanical ventilation
 Maximal inspiratory pressure−0.182−0.162
 Maximal inspiratory pressure, % predicted−0.105−0.029
 Diaphragm thickness−0.257−0.163
 Diaphragm thickening ratio−0.106−0.137
 6MWD−0.389**−0.365**
 6MWD % predicted−0.427**−0.389**
 Dyspnoea mMRC score0.424**0.183
 SGRQ0.1600.127

6MWD: 6-min walk distance; mMRC: modified Medical Research Council; SGRQ: St George's Respiratory Questionnaire. *: p<0.05; **: p<0.01.