Monitoring and regulation of supported breathing in Intensive Care

This thesis describes several chapters related to monitoring and regulation of breathing. The main goal is to provide better insight in the interaction between spontaneous breathing and mechanical ventilatory support. In chapter 2 we investigated the effect of metabolic alkalosis on the ventilatory response. To analyze whether speckle tracking ultrasound can be used to noninvasively quantify diaphragm contractility, in chapter 3 this technique is used in healthy subjects undergoing a randomized stepwise threshold loading protocol. Chapters 4, 5 and 6 of this thesis focus on the interaction between the two parallel systems involved in providing adequate ventilation: the patient and more specific its upper airway, and the ventilator. We studied this interaction in patients with an acute exacerbation of COPD during noninvasive ventilation

Surface electromyography to quantify neuro-respiratory drive and neuro-mechanical coupling in mechanically ventilated children

Background: The patient’s neuro-respiratory drive, measured as electrical activity of the diaphragm (EAdi), quantifies the mechanical load on the respiratory muscles. It correlates with respiratory effort but requires a dedicated esophageal catheter. Transcutaneous (surface) monitoring of respiratory muscle electromyographic (sEMG) signals may be considered a suitable alternative to EAdi because of its non-invasive character, with the additional benefit that it allows for simultaneously monitoring of other respiratory muscles. We therefore sought to study the neuro-respiratory drive and timing of inspiratory muscles using sEMG in a cohort of children enrolled in a pediatric ventilation liberation trial. The neuro-mechanical coupling, relating the pressure generated by the inspiratory muscles to the sEMG signals of these muscles, was also calculated. Methods: This is a secondary analysis of data from a randomized cross-over trial in ventilated patients aged &lt; 5 years. sEMG recordings of the diaphragm and parasternal intercostal muscles (ICM), esophageal pressure tracings and ventilator scalars were simultaneously recorded during continuous spontaneous ventilation and pressure controlled-intermittent mandatory ventilation, and at three levels of pressure support. Neuro-respiratory drive, timing of diaphragm and ICM relative to the mechanical ventilator’s inspiration and neuro-mechanical coupling were quantified. Results: Twenty-nine patients were included (median age: 5.9 months). In response to decreasing pressure support, both amplitude of sEMG (diaphragm: p = 0.001 and ICM: p = 0.002) and neuro-mechanical efficiency indices increased (diaphragm: p = 0.05 and ICM: p &lt; 0.001). Poor correlations between neuro-respiratory drive and respiratory effort were found, with R2: 0.088 [0.021–0.152]. Conclusions: sEMG allows for the quantification of the electrical activity of the diaphragm and ICM in mechanically ventilated children. Both neuro-respiratory drive and neuro-mechanical efficiency increased in response to lower inspiratory assistance. There was poor correlation between neuro-respiratory drive and respiratory effort. Trial registration: ClinicalTrials.gov ID NCT05254691. Registered 24 February 2022, registered retrospectively.</p

Speckle tracking echography allows sonographic assessment of diaphragmatic loading

Introduction: Assessment of diaphragm function should ideally be assessed using magnetic twitch pressure or esophageal and gastric balloons. Conventional sonographic techniques as thickness and fractional thickening (FT), only provide limited insight in diaphragm function. Speckle tracking echocardiography allows reliable quantification of muscle function by tracking of grey patterns and their motion; strain as parameter of muscle deformation and strain rate as deformation velocity. Aim: To investigate whether speckle tracking can quantify loading of the diaphragm, superior to FT. Methods: 13 healthy volunteers underwent an inspiratory loading protocol with recording of transdiaphragmatic pressure (Pdi) and diaphragm electromyography (EMGdi). Inspiratory loading of 0 to 30% of maximal inspiratory pressure was applied in random order for 5 minutes per applied load. Diaphragmatic sonography was performed using a 2-4 MHz linear phased array transducer positioned at the right-lateral thoracic wall in the anterior axillary line longitudinal to the body axis. Ultrasound recordings of the diaphragm were made at the marked location during 10 seconds. Results: Increased inspiratory loading increased Pdi and EMGdi. Sonographic markers of contractility increased with incremental loading. Pdi correlated with strain (r=0.75; p=0.000) and strain rate (r=0.77; p=0.000). Contrarily, FT was not correlated with Pdi. Conclusion: Speckle tracking of the diaphragm can detect changes in diaphragmatic loading up to 30% of maximal inspiratory pressure. It might be a valuable tool to detect changes in loading in specific patient categories, including patients with acute respiratory failure and ventilated ICU patients

ReSurfEMG

Commits &lt;ul&gt; &lt;li&gt;00b83ff: cleaning cff (C. Moore)&lt;/li&gt; &lt;/ul&gt;If you use this software please cite as belo