A Structured Approach to Extubation in Mechanically Ventilated Rats

Mechanical ventilation is lifesaving, but it can cause brain and die from injury. We aim to develop a extubation model in rats. This model simulates clinical weaning to study this injury better.

Currently, most mechanical ventilation models only look at short-term effects and mainly use a tracheostomy, which limit clinical relevance. Tracheostomy makes the ventilation earlier, but bypasses the upper airway, raising the risk of lung infection and disrupting brain signaling. This make it hard to study injury and recovery accurately.

We're filling the gap in rat models by creating a clear, step-by-step extubation protocol. It follows clinical practice, lowers complications, and helps rats recover more safely after ventilation. Using this extubation model, we aim to investigate the molecular mechanisms underlying ventilator-induced injuries to the brain and the diaphragm as well as the biological pathways involved in their potential recovery.

To begin, prepare the ventilator and adjust the oxygen concentration. Get the intubation device ready, and position the anesthetized rat for intubation. Using forceps, gently pull the rat's tongue toward the right oral corner.

Insert the intubation device at the base of the tongue and advance it toward the epiglottis. Then lift the device tip to expose the glottis, and insert the endotracheal tube into the trachea during inhalation. Once the tube is in place, connect the rat to the ventilator.

Now set the ventilator parameters based on the rat's weight and experimental requirements. Infuse propofol continuously using a syringe pump to maintain anesthesia. Monitor the rat's blood gas levels throughout the procedure to ensure respiratory stability.

For weaning, reduce the propofol infusion rate by 50%using the syringe pump settings, and waiting for approximately 10 minutes for the sedation level to decrease. Disconnect the rat from the ventilator for one to two minutes to assess readiness for weaning. During this period, ensure the respiratory rate is between 60 to 70 breaths per minute, confirm a chest displacement of at least one millimeter, and verify that arterial blood gas values and pH levels are within acceptable ranges.

If all parameters are met, disconnect the ventilator. To prepare the rat for extubation, use a custom-made face mask to ensure adequate oxygenation. Then observe the rat's skin color to assess oxygenation.

Using a self-made suction device, perform suctioning at a rate of approximately two milliliters per second for three to four seconds per session to clear airway secretions. Next, using a two-handed technique, stabilize the rat's head with the left index finger and thumb. Then gently remove the endotracheal tube with the right index finger and thumb.

Discontinue the propofol infusion once the tube is removed. Monitor the rat's vital signs post-extubation, and continue providing oxygenation as needed using the custom face mask. In the structured protocol applied to 20 rats, all extubations were successful, with full recovery achieved in approximately 48.5 minutes post-extubation.

During the approaching weaning step, average oxygen partial pressure was 87.6 millimeters of mercury, carbon dioxide partial pressure was 43.2 millimeters of mercury, and pH was 7.421. No complications were reported during either the extubation phase or the post-extubation care period.