Incorporating Patient Assist Mode: The ABBU Experience

The Automated Bag Breathing Unit (ABBU) is a low-cost, rapid solution when full-featured ventilators are unavailable. An adult resuscitation bag-valve was interfaced with a lever arm and programmable electric motor and low-flow oxygen source. Output parameters were validated with a Michigan dual-lung simulator followed by animal model testing. ABBU synchronous operation utilizes patient assist algorithm. The algorithm was developed and adjusted during the preliminary pig study. A “true positive” is defined as the patient initiating a breath and ABBU delivered an assist within 160 ms. 80 ms of this delay corresponds to the time it takes the patient to drop their airway pressure, and the other 80 ms is the time for ABBU to detect and move the arm initiating airflow from the bag. In summary, the patient assist algorithm was tested over a wide range of situations, from light anesthesia to heavy distress. Unless there was a disconnect or line suction, ABBU could effectively calculate PEEP. Once there is an accurate PEEP, the operator was able to set the threshold to minimize false positives and false negatives.