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Non-invasive diagnostic tools for the evaluation of diaphragm function in mechanically ventilated ICU patients

Hoofs, M.A. (2019) Non-invasive diagnostic tools for the evaluation of diaphragm function in mechanically ventilated ICU patients.

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Abstract:INTRODUCTION: Diaphragm dysfunction is a common complication in critically ill mechanically ventilated ICU patients. Monitoring diaphragm function could help in facilitating diaphragm protective ventilation. The current gold standard for assessing diaphragm function, transdiaphragmatic pressure (Pdi), is invasive and has disadvantages. Ultrasound has been proposed as an alternative to assess diaphragm function, but basic measurement options, such as fractional thickening, are not sufficient. More sophisticated ultrasound techniques, speckle tracking and tissue Doppler imaging (TDI), could be used to assess diaphragm function. Furthermore, the airway occlusion pressure in the first 100ms (P0.1) is a measure for respiratory drive and could be of use to assess the pressure produced by all the respiratory muscles. Thus, the aim of this research is to evaluate the role of different non-invasive monitoring tools for the evaluation of diaphragm function in mechanically ventilated ICU patients. METHODS: Speckle tracking and TDI (color and pulsed wave (PW)) have been tested upon their feasibility in assessing diaphragm function. An algorithm for speckle tracking has been developed and tested by repeated measurements (5 times). Furthermore, color-TDI was tested upon reliability and validity in healthy subjects (n=5) by repeated, simultaneous measurements of flow and breathing along a fixed breathing pattern. M-mode measurements were performed as control measurement. Besides ultrasound, P0.1 was compared to the pressure generated by all the inspiratory muscles (Pmus) based on two different methods, the Mancebo and the Maquet method, and were compared to control values of ICU patients on supported ventilation (n=14). RESULTS: Speckle tracking as it was available at the ICU was not feasible to assess diaphragm function. However, developing an algorithm was feasible, and showed a similar mean and small standard deviation, except for some cases where the tracking was unsuccessful. Pulsed wave TDI was proven to be not feasible. Color-TDI was feasible to assess diaphragm function and had a coefficient of variance of 6.6% per breath. Repeated measurements showed similar coefficient of variances between TDI and M-mode (15% to 11% for inspiration and 10% to 15% for expiration, respectively). Displacement values for M-mode were considerably higher than measured in color-TDI. Color-TDI had a lower correlation for inspiration and expiration (R2=0.49 p<0.001) compared to M-mode (R2=0.94 p<0.001). P0.1 was not correlated with Pmus, as P0.1 values between 1.5 and 3.5 cmH2O corresponded to Pmus values between 3 and 21 cmH2O. CONCLUSION: More sophisticated ultrasound techniques, speckle tracking and tissue Doppler imaging, as available at the ICU, are not yet applicable to assess diaphragm function. Speckle tracking could potentially be a technique to assess diaphragm function but needs further improvement and testing. P0.1 and Pmus are not correlated and P0.1 does not represent total inspiratory effort of the muscles.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
Link to this item:http://purl.utwente.nl/essays/79609
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