EIT Evaluation of the Impact of Inhaled Nitric Oxide on Ventilation/Perfusion Mismatch in ARDS Patients Receiving Noninvasive Respiratory Support

EIT Evaluation of the Impact of Inhaled Nitric Oxide on Ventilation/Perfusion Mismatch in ARDS Patients Receiving Noninvasive Respiratory Support: A Prospective Physiological Study

This study aimed to quantitatively evaluate the immediate effect of inhaled nitric oxide on the ventilation / perfusion ratio in ARDS patients receiving nasal high flow oxygen therapy or noninvasive ventilation using electrical impedance tomography.

The immediate effect of different doses of iNO (5-40 ppm) on the degree of v/q mismatch in the lungs of ARDS patients receiving hfnc or NIV was quantitatively evaluated by EIT. Objective to explore the effects of different doses of iNO on oxygenation, ventilation distribution and perfusion distribution in ARDS patients using hfnc or NIV, as well as the differences and influencing factors of individual response.

Inclusion Criteria:

1. Age ≥ 18 years, gender unlimited;
2. Non invasive ventilation (NIV) with PEEP or CPAP ≥ 5 cmH2O or nasal high flow oxygen therapy (hfnc) with flow rate ≥ 30 l/min met the diagnostic criteria of non intubated ARDS according to the new global definition of ARDS: pao2/fio2 ≤ 300MMHG or spo2/fio2 ≤ 315 (SpO2 ≤ 97%);
3. Patients with spontaneous breathing and clear consciousness can cooperate with instructions and hold breath for ≥ 8s;
4. Patients with spontaneous breathing and clear consciousness can cooperate with instructions and hold breath for ≥ 8s;

Exclusion Criteria:

1. There are signs of worsening respiratory failure requiring immediate intubation: respiratory rate > 40 times / min with severe use of auxiliary respiratory muscles or contradictory breathing, or Paco ₂ > 50 mmHg and pH < 7.25;
2. Hemodynamic instability or the presence of refractory shock; That is, the vasoactive drugs increased by more than 30% within 6 hours, or the norepinephrine dose exceeded 0.5 μ g /kg/min;
3. There are contraindications to EIT monitoring, such as thoracic implantable defibrillator / pacemaker, large area of severe skin damage on the chest, serious allergy to electrode patches, etc;
4. There are contraindications to the use of iNO: such as severe left ventricular dysfunction, active bleeding, etc;
5. Patients with intracranial hypertension, severe arrhythmia or digestive tract obstruction;
6. Pneumothorax and massive pleural effusion were not treated;
7. Chronic kidney disease;
8. Pregnant or lactating women;
9. Participating in other studies;
10. The investigator judged that there were any other circumstances not suitable for participation in this study. -