Leveraging Learning in Intensive Care

Chi-Sang Poon, a research scientist at the Harvard-MIT Division of Health Sciences and Technology (HST), and colleagues examined rats under mechanical ventilation to see how they applied different forms of nonassociative learning to adapt to the rhythm imposed by the respirator.

Existing respirators do not consider the adaptive nature of breathing in their design. Some ignore the patient's natural rhythm and pump air in and out of the lungs on set intervals. As a result, doctors often must sedate or paralyze patients to prevent them from fighting an unfamiliar rhythm. Other respirator designs rely entirely on the patient to trigger the airflow. These systems, however, are costly and tend to be unreliable for weak patients such as newborns or those in critical care.

The MIT research suggests, however, that if a doctor takes the patient's natural breathing rhythm into account and sets the ventilator's rhythm in that same range, the patient will adapt and synchronize with the ventilator. This new approach could minimize the need for induced sedation or paralysis.

„We have intrinsic nonassociative learning capabilities, called habituation and desensitization, that [can] make up for changes in the spontaneous rhythm due to artificial lung inflation,“ says Poon.

In tests of rats under artificial respiration, Poon found that, if using a suitable rhythm, rats adapted to the mechanical ventilation. He also found that this learning capability enabled mice to adapt to an artificial rhythm even when the mechanical respirators applied constant air pressure. The rats effectively „tuned out“ this extra pressure, filtering it out as background noise. When Poon disabled the neural pathways involved in nonassociative learning, the rats' ability to adapt was either eliminated or compromised.

COMPAMED.de; Source: Massachusetts Institute of Technology