Hering-Breuer Reflex
Conditions
Keywords
Hering-Breuer reflex, Bilateral Lung Transplant
Brief 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.
Interventions
DEVICENasogastric tube placement and elicitation of Hering-Breuer reflex
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).
Sponsors
Policlinico Hospital
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
The study will be conducted on two groups of subjects: * Patients admitted to the Intensive Care Unit for post-operative care following bilateral lung transplantation (Group 1); * Patients admitted to the Intensive Care Unit for post-operative care or monitoring after non-thoracic surgery (Group 2 - control group)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* 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 criteria
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| THBR/TSPONT ratio | At the enrollment | Comparison of the ratio between the diaphragm electrical activation time after a high-volume breath aimed at eliciting the HBR (THBR) and a spontaneous breath (TSPONT), i.e., the THBR/TSPONT ratio, between patients who underwent bilateral lung transplantation and those who underwent non-thoracic surgery. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| The variation of the THBR/TSPONT ratio as a function of PEEP | At the enrollment | Variation of the THBR/TSPONT ratio calculated at two different PEEP levels (8 and 12 cmH₂O) in patients who underwent bilateral lung transplantation and in those who underwent non-thoracic surgery. |
Countries
Italy
Outcome results
None listed