Medical Research Council Scale Predicts Spontaneous Breathing Trial Failure and Difficult or Prolonged Weaning of Critically Ill Individuals.

BACKGROUND: Handgrip strength is an alternative measure to assess peripheral muscle strength and is correlated with the Medical Research Council (MRC) scale, with promising values for diagnosing ICU-acquired weakness (ICUAW). Because ICUAW has been associated with delayed weaning from mechanical ventilation, we hypothesized that ICUAW evaluated with both the MRC scale score and handgrip strength are associated with failure of a spontaneous breathing trial (SBT) and duration of mechanical ventilation weaning. METHODS: We conducted a prospective observational study in 3 general ICUs with a total of 54 beds at 2 academic hospitals. Adult subjects with > 48 h of mechanical ventilation who were eligible for weaning were included in the study. RESULTS: In the evaluation before the first SBT, the MRC score (P < .001) and handgrip strength (P < .001) were significantly different between subjects extubated after a successful first SBT (simple weaning) and those extubated any time after a failed first SBT (difficult weaning). Only the MRC score discriminated between first SBT success or failure (P < .001); in multivariate analysis, the MRC score was significantly associated with first SBT failure (odds ratio 0.91, 95% CI 0.88-0.97, P < .001) and difficult weaning (odds ratio 0.91, 95% CI 0.87-0.96, P < .001). Handgrip strength exhibited good accuracy in identifying ICUAW. CONCLUSIONS: MRC score was independently associated with SBT failure and difficult or prolonged weaning.

Preoperative expiratory and inspiratory muscle weakness to predict postoperative outcomes in patients undergoing elective cardiac surgery.

BACKGROUND: Few studies have evaluated preoperative respiratory muscle strength as a risk factor for postoperative morbidity and mortality. The objective of this study was to evaluate the association of preoperative inspiratory muscle weakness (IMW) and preoperative expiratory muscle weakness (EMW) with duration of mechanical ventilation, length of stay in the intensive care unit (ICU), incidence of postoperative pulmonary complications (PPCs), and mortality in patients undergoing elective cardiac surgery. MATERIALS AND METHODS: This was a prospective observational study. Patients admitted for elective cardiac surgery were recruited. Maximal inspiratory and expiratory pressure were measured before surgery. A multivariate regression model was used to adjust for possible confounding variables and test the association of IMW and EMW with the duration of mechanical ventilation, length of stay in the ICU, PPCs, and hospital mortality. RESULTS: Two hundred and fifty-five patients were included in this study. The presence of IMW was associated with an increase in the duration of mechanical ventilation (P = .012). The presence of EMW was associated with a reduction in the incidence of PPCs (P = .005). IMW had no significant association with length of stay in the ICU, PPCs, or hospital mortality. EMW had no significant association with the duration of mechanical ventilation, length of stay in the ICU, or hospital mortality. CONCLUSIONS: In patients undergoing elective cardiac surgery, preoperative IMW is associated with the duration of mechanical ventilation while preoperative EMW is associated with a decrease in PPCs.