Post-intubation pulmonary function test in Guillain-Barre syndrome

The value of daily postintubation respiratory function tests in predicting duration of ventilation in 37 mechanically ventilated patients with Guillai n-Barre syndrome (GBS) was studied. Patients ventilated for less than 3 wee ks were compared with those ventilated more than 3 weeks. Daily vital capac ity and maximal inspiratory and expiratory pressures were summed to an inte grated pulmonary function (PF) score. We calculated the PF ratio, which rep resents the PF score at day 12 after intubation divided by the PF score on the day of intubation. The PF ratio was greater than 1 in all 10 patients v entilated less than 3 weeks and was less than 1 in 19 of 27 patients ventil ated for longer (P = 0.0001, Fisher exact test). The sensitivity of a PF ra tio less than 1 for predicting duration of ventilation greater than 3 weeks was 70%; the specificity and positive predictive value were 100%. This stu dy thus suggests that serial postintubation respiratory tests can provide a measure of respiratory status in patients with GBS. These parameters may h elp predict duration of ventilation and need for tracheostomy. if, at day 1 2, the PF ratio is less than 1, it is highly unlikely that patients will be weaned within 3 weeks, and tracheostomy should be performed. If the ratio is greater than 1, tracheostomy should be deferred, because a substantial p roportion of these patients may be successfully weaned from the ventilator within 3 weeks. (C) 2000 John Wiley & Sons, Inc.