High-flow oxygen therapy in single lung transplantation: assessment of pulmonary gas distribution using electrical impedance tomography
Ignacio Fernandez Ceballos1, Joaquin Ems2, Emilio Steinberg1, Indalecio Carboni Bisso1, Matias Madorno2, Marcos Jose Las Heras1.
1Intensive Care Unit, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina; 2MBMED, Buenos Aires, Argentina
Introduction: Ventilatory support in patients with Single Lung Transplant (SLT) is considered challenging since it is performed on a respiratory system that presents lungs with different compliance. High-Flow Oxygen Therapy (HFOT) has proven benefits on end-expiratory lung volume, but its impact on SLT patients is still uncertain. The use of Electric Impedance Tomography (EIT), provides information of ventilation distribution globally and regionally, allowing impact assessment of the application of HFOT in such patients.
Methods: Case Report of a patient with precedent of Chronic obstructive pulmonary disease (COPD) and SLT. Both Tidal impedance (Tz), End-Expiratory Lung Impedance (EELI), as well as Global Inhomogeneity index (GI), and expiratory time constant were assessed with EIT. The measurements were made in spontaneous breathing on 3 scenarios: tracheostomy with conventional oxygen, nasal and tracheostomy HFOT.
Results: Spontaneous breathing through tracheostomy was taken into account as a reference, and showed that Tz and EELI was greater in the Native Lung (NL) (63% and 53%, respectively). When nasal HFOT was applied, the global Tz decreased by 12%, and the global EELI increased by 6.8%. Additionally, regional Tz decreased by 7.6% in the NL, while the regional EELI increased by 15.1%. Consequently, the global and NL GI increased by 11.5% and 17.8% respectively, generating an increase in the expiratory time constant, evidencing air trapping of the NL. The Transplanted Lung (TL) did not show significant differences in the EELI (decrease of 0.7%), but a 18.9% reduction in the Tz was observed. When applying tracheostomy HFOT, the distribution of ventilation was observed as being similar to the use of nasal HFOT, but with greater impact on the global EELI (increase of 8.9%) at the expense of an increase in the EELI of the NL (increase of 23.3%). As with tracheostomy HFOT, there was air trapping in the NL with no benefits in the TL.
Conclusion: The use of EIT evidenced that the application of nasal and tracheal HFOT notoriously increased heterogeneity of the distribution of ventilation, generating as a result dynamic hyperinflation in the NL with no benefits in the TL.
