Abstract
BackgroundCritically ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Inspiratory muscle training (IMT) can improve respiratory muscle strength. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown.AimTo compare changes in muscle oxygenation parameters of scalene and sternocleidomastoid inspiratory muscles during a standardized task between patients with weaning difficulties who received either high-intensity IMT (intervention) or sham low-intensity IMT (control).MethodForty-one patients performed daily IMT sessions (4 sets, 6–10 breaths) until weaning success or for 28 consecutive days. The training load was progressively adjusted in the intervention group (n = 22) to the highest tolerable load, whilst the control group (n = 19) kept training at 10% of their baseline maximal inspiratory pressure (PImax). Breathing characteristics (i.e., work and power of breathing, PoB), respiratory muscle function [i.e., PImax and forced vital capacity (FVC)] were measured during a standardized loaded breathing task against a load of 30% of baseline PImax before and after the IMT period. In addition, during the same loaded breathing task, absolute mean and nadir changes from baseline in local scalene and sternocleidomastoid muscle oxygen saturation index (Δ%StiO2) (an index of oxygen extraction) and nadir Δ%StiO2 normalized for the PoB were measured by near-infrared spectroscopy.ResultsAt post measures, only the intervention group improved mean PoB compared to pre measures (Pre: 0.42 ± 0.33 watts, Post: 0.63 ± 0.51watts, p-value < 0.01). At post measures, both groups significantly improved nadir scalene muscles StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) compared to pre measurements and the improvement was not significant different between groups (p-value = 0.40). However, at post measures, nadir sternocleidomastoid muscle StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) was significantly greater improved in the intervention group (mean difference: +18.4, 95%CI: −1.4; 38.1) compared to the control group (mean difference: +3.7, 95%CI: −18.7; 26.0, between group p-value < 0.01). Both groups significantly improved PImax (Intervention: +15 ± 13 cmH2O p-value < 0.01, Control: +13 ± 15 cmH2O p-value < 0.01). FVC only significantly improved in the intervention group (+0.33 ± 0.31 L p < 0.01) report also change in control group.ConclusionThis exploratory study suggests that high-intensity IMT induces greater improvements in scalene and sternocleidomastoid muscle oxygenation parameters attributed for oxygen delivery, utilization and oxygen saturation index compared to low-intensity IMT in patients with weaning difficulties.
Highlights
20% of mechanically ventilated patients admitted to the intensive care unit (ICU) experience difficulties with weaning from the mechanical ventilation (Beduneau et al, 2017; Jeong et al, 2018)
Patients were recruited from a larger-ongoing Randomized Controlled Trial (RCT) that aims to evaluate the effects of a novel Inspiratory muscle training (IMT) method on weaning outcomes in selected patients with weaning difficulties (Hoffman et al, 2018)
Between September 28, 2018 and November 10, 2020, 2,478 mechanically ventilated patients admitted to the surgical and medical ICU were screened for eligibility of which 47 patients were randomized in the study
Summary
20% of mechanically ventilated patients admitted to the intensive care unit (ICU) experience difficulties with weaning from the mechanical ventilation (Beduneau et al, 2017; Jeong et al, 2018). Patients requiring prolonged invasive mechanical ventilation are prone to develop respiratory and locomotor muscle weakness and have an increased risk of infection, complications, and mortality (Dres et al, 2019; Piva et al, 2019; Sklar et al, 2020; Burns et al, 2021). Ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown
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