The non-significant trends on the remaining outcomes favour inspiratory muscle training over control and the 95% CIs contain clinically worthwhile benefits, strongly suggesting
that further research is required. However, it is not possible to provide a recommendation Paclitaxel clinical trial to implement the training to facilitate weaning from mechanical ventilation based on the current evidence. Although individual studies varied in their conclusions about the effect of inspiratory muscle training on maximal inspiratory pressure, the pooled data show that the training significantly increases inspiratory muscle strength. At present there is no established minimum clinically important difference in maximal inspiratory pressure in this patient group. The mean pressures recorded at baseline in the three included studies ranged from 15 to 51 cmH2O, which is below the predicted normal for healthy individuals (ATS/ERS, 2002). Even after training in the experimental group, the mean maximal inspiratory pressures in all studies ranged from 25 to 56 cmH2O, which remain substantially lower than normal values. Sahn and Lakshminaryan (1973) suggested that a low maximal inspiratory pressure was an important predictor of weaning failure, although this finding has not been reproduced consistently in the literature Volasertib nmr (Bruton et al 2002). These results must be interpreted in the context
of the reliability of inspiratory muscle strength measures in ventilated patients. It has been highlighted that maximal inspiratory pressure is difficult to measure reliably in intubated patients (Bruton et al 2002). This has been overcome by the use of a unidirectional valve, which allows maximal inspiratory
pressure to be performed easily even in unco-operative patients (Caruso et al 1999, Eskandar and Apostolakos 2007). Using a unidirectional valve requires a physiological response demanding less patient co-operation, and is more accurate than other methods of measuring maximal inspiratory pressure (Caruso et al 1999). This technique was used by the aminophylline authors in all three studies. Authors have suggested using the maximal value of three manoeuvres to minimise variability (Caruso et al 2008, Marini et al 1986) however only one included study (Martin et al 2011) reported undertaking such repetitions. Although a unidirectional valve was used, measurement variability could occur due to the effects of controlled ventilation, varying levels of consciousness and sedation. However, this technique currently represents the best method for estimating inspiratory muscle strength in mechanically ventilated patients (Caruso et al 1999, Caruso et al 2008). Due to the design of the studies, the experimental group had greater opportunity to practise the maximal inspiratory pressure measurement procedure, eg, during titration of the training load, and to accommodate to the feeling of loaded breathing during training.