Breathing through a straw : inspiratory imposed work of breathing for children

Jansen, A.S. and Schuurman, M. and Urgert, T. and Wijlens, K.A.E. (2016) Breathing through a straw : inspiratory imposed work of breathing for children.

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Abstract:INTRODUCTION: The decision to disconnect and extubate a child from the mechanical ventilator is based on the clinical appearance of the patient. Between 10 to 20% of these extubations fail and require reintubation. It is proven that 40 – 90% of these patient show signs of laryngeal damage, oedema or pneumonia. A new option to avoid premature extubation is to first let the child breathe spontaneously through the endotracheal tube (ETT). To allow the patient to breathe spontaneously through the ETT he has to overcome the imposed work of breathing (WOBimp). It is still questioned whether the ETT provides significant extra work of breathing during spontaneously breathing or not. OBJECTIVE: The aim of this bench study is to determine the inspiratory WOBimp for an ETT and the contribution of it to the total work of breathing during spontaneously breathing in children. METHODS: A setup with a mechanical test lung driven by a mechanical ventilator was used to simulate spontaneously breathing. Four ETTs with the respectively inner diameters of 3.0, 3.5, 4.0 and 4.5 mm were connected to the test lung and ventilated at five different tidal volumes. The flow and pressure at the proximal and distal end for each ETT were obtained to determine the inspiratory WOBimp. The inspiratory WOBimp was also analytical calculated to observe a possible correlation. RESULTS: ETTs with smaller diameters show a higher inspiratory WOBimp. Furthermore, breathing through an ETT at a higher tidal volume causes a higher inspiratory WOBimp. The values for the analytical calculated inspiratory WOBimp are lower than the measured values. CONCLUSION: It can be concluded that spontaneously breathing through an ETT provides extra work for children. The percentage of extra work provided by the inspiratory WOBimp for the 3.0, 3.5, 4.0 and 4.5 mm ETTs at 5 (mL/kg) is respectively 8-17%, 7-15%, 16-33% and 11-22%. Percentages of extra work at 7.5 (mL/kg) are respectively 16-31%, 13-25%, 24-47% and 19-37%. Assuming an acceptable inspiratory WOBimp is 1/5th of the WOB, most of the percentages of 5 mL/kg fit this criteria. The percentages of the 7.5 mL/kg partly meets the criteria. Based on this assumption children who breathe at a volume of 5 mL/kg can breathe spontaneously through the ETT. RECOMMENDATIONS: Further research is needed to investigate the reference values of the WOB and WOBimp during spontaneously breathing in children. This bench study should also be performed in an in vivo setting. KEYWORDS: inspiratory imposed work of breathing, endotracheal tube, children, extubation
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general
Programme:Technical Medicine BSc (50033)
Link to this item:http://purl.utwente.nl/essays/70415
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