Discussion
cough, myopathy, PCF increase, C-SCI
MYOPATHY
Overall, this study revealed that there was no difference in PCF between the supine and reclined positions when MI-E was applied to patients with C-SCI. However, the generated PCF was affected by the application maneuver and MI-E with additional manual thrust resulted in the most substantial increase, approximately 2.116 [2.005–2.228] L/s, compared to voluntary cough. Although the body position itself did not directly alter PCF, the PCF increase from different maneuvers could be influenced by the position, resulting in a larger PCF increase in the reclined position. The provided TIV and individual differences in baseline pulmonary function made a difference of approximately 0.114–0.265 L/s.The estimated mean PCF [95% confidence interval] was 1.808 [1.610–2.006], 3.529 [3.335–3.723], 3.925 [3.732–4.118] L/s when supine and 1.672 [1.471–1.873], 3.598 [3.405–3.792], 3.909 [3.716–4.103] L/s when reclined from voluntary cough, MI-E, and MI-E with manual thrust, respectively, after adjusting the covariance of TIV and random effects of individual differences. The positional difference of the PCF only existed during voluntary coughing, and the final PCFs generated during MI-E assist or additional manual thrust were not different between the two applied positions. Although voluntary cough did not reach the 2.7 L/s threshold, which is considered essential for efficient sputum clearance from the lungsAlthough voluntary PCF was faster in the supine position compared to the reclined position, the increase in PCF from MIE-assist or additional manual thrust was more pronounced in the reclined position, ultimately resulting in a similar final PCF in both positions. It is also well correlated with the significant interaction factor between maneuver and position (Table A previous study investigating 36 patients with NMD suggested that the best individual PCF could be achieved with intermittent positive pressure breathing-assisted insufflationPrevious reports have shown an additional benefit of combining manual thrust with MI-E in patients with NMD, including myopathy or motor neuron disease, however, there is very little information regarding MI-E with manual thrust in tetraplegic individuals. Kim et al.Although PCF variations caused by the assistance of MI-E or manual thrust have been documented in different populations as mentioned aboveThis study had some limitations. First, we only measured PCF during cough but could not measure the exact amount of eliminated sputum to assess the effectiveness of the procedure in maintaining pulmonary hygiene. Additionally, comparing MI-E-assisted cough at 60° or 90° sitting position can provide more information about the best position for MI-E in people with C-SCI as well. Furthermore, information on long-term pulmonary prognosis, which is affected by the body position applied for MI-E treatment, will further empower future clinical decisions. Last, this pilot study is limited by a small, heterogeneous sample of individuals with varying SCI severities, restricting the generalizability of findings. The estimated sample size for paired t-tests is notably high due to the small mean differences relative to the standard deviations of differences. For instance, n = 557 would be needed for MI-E assisted cough, and n = 80,602 for assessing positional differences during MI-E combined with manual thrust. Therefore, it is imperative to utilize a small sample size but incorporate multiple, repetitive measures using LMM.In conclusion, the PCF during MI-E does not change according to the position, but a beneficial effect of applying MI-E and additional manual thrust could be achieved in both the supine and reclined positions. Generated TIV during cough was important in determining PCF in both positions. Hence, either position can be used as long as MI-E can be performed together with manual thrust and sufficient TIV is provided.