The Hering-Breuer Reflex in Bilateral Lung Transplant Patients
Policlinico Hospital
22 participants
Oct 7, 2025
INTERVENTIONAL
Conditions
Summary
The goal of this clinical trial (non-pharmacologic, single-center) is to determine whether the Hering-Breuer inflation reflex is preserved-and how it is modulated by end-expiratory pressure-in adult intensive-care patients who have undergone bilateral lung transplantation. The study will enroll men and women ≥ 18 years admitted to the ICU during the early weaning phase and will include a comparison group of intubated ICU patients after major non-thoracic surgery. The main questions it aims to answer are: * Is the Hering-Breuer reflex (measured as the ratio THBR/TSPONT) absent or attenuated in double-lung-transplant recipients? * Does changing the level of positive end-expiratory pressure (PEEP 8 vs 12 cmH₂O) influence the reflex? Comparison group: Researchers will compare the transplant arm (post-bilateral lung transplantation) with the control arm (post-operative, non-thoracic surgery patients) to see whether loss or blunting of the reflex-and its response to PEEP-differs between the two cohorts. Participants will: * Have a nasogastric catheter with embedded electrodes positioned to record the electrical activity of the diaphragm (EAdi). * Be ventilated in pressure-support mode at two preset PEEP levels (8 cmH₂O and 12 cmH₂O) during the weaning phase. * Receive one standardized high-volume insufflation at \~30 cmH₂O in each PEEP condition to elicit the reflex, while EAdi, airway pressures, inspiratory/expiratory times, and tidal volumes are recorded for 10 minutes per level.
Eligibility
Inclusion Criteria4
- Age >18 years;
- Both sexes;
- For group 1: patients admitted to the Intensive Care Unit after undergoing bilateral lung transplantation, during respiratory weaning;
- For group 2: patients admitted to the Intensive Care Unit for support or monitoring after non-thoracic surgery, who will arrive intubated.
Exclusion Criteria14
- For group 1, patients meeting at least one of the following criteria will be excluded:
- Re-transplantation or single-lung transplantation;
- Urgent lung transplantation;
- Post-transplant respiratory system compliance < 30 mL/cmH₂O;
- Hemodynamic instability (defined as the presence of one or more of the following: plasma lactate > 4 mmol/L, need for vasoactive support with norepinephrine and/or epinephrine at a dose > 0.05 mcg/kg/min, systolic arterial pressure < 80 mmHg);
- Increased risk of bleeding related to the placement of a nasogastric tube due to coagulopathy or severe thrombocytopenia (INR > 2 and platelets < 70,000);
- Pregnancy
- For group 2, patients presenting with one or more of the following criteria will be excluded:
- Postoperative respiratory system compliance < 30 mL/cmH₂O;
- Hemodynamic instability (defined as the presence of one or more of the following: plasma lactate > 4 mmol/L, need for vasoactive support with norepinephrine and/or epinephrine at a dose > 0.05 mcg/kg/min, systolic arterial pressure < 80 mmHg);
- Contraindications to nasogastric tube placement (gastroesophageal surgery within the last 3 months, gastroesophageal bleeding in the previous 30 days, esophageal varices, facial trauma);
- Increased risk of bleeding related to the placement of a nasogastric tube due to coagulopathy or severe thrombocytopenia (INR > 2 and platelets < 70,000);
- History of lung transplantation or major thoracic surgery;
- Pregnancy.
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Interventions
Enrolled patients will have a nasogastric tube placed, through which diaphragmatic electrical activity will be measured. Patients will be ventilated in pressure support mode with an expansion breath delivered at a maximum pressure of approximately 30 cmH2O in order to elicit the Hering-Breuer Reflex. Diaphragmatic electrical activity, timing, volumes and pressures will then be analyzed before and after the expansion breath over a 10 minute period, testing two levels of PEEP (8 and 12 cmH2O).
Locations(1)
View Full Details on ClinicalTrials.gov
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NCT07280611