Bunnell History and High Frequency Jet Ventilator Theory
High Frequency Jet VentilationFrom an Idea to a Device
"The substance of the lung is dilatable and extensible like the tinder made from a fungus. But it is spongy and if you press it, it yields to the force whichcompresses it, and if the force is removed, it increases again to its original size." -- Leonardo da Vinci, late 15th century
"The gust of wind driven out of the lung in the generation of a large breath comes from the aid ofthe abdominal wall which compresses the intestines, and they elevate the diaphragm which compresses the lungs." - da Vinci
Adults were studied thoroughly . . . but not babies.
Dr. Bunnell performs early aerosolizedsurfactant studies at MIT in early 1970s.Observes many babies dying or beingseverely injured by early mechanicalventilators.Dr. Bunnell: “Is it possible to ventilate babies with smaller tidal volumes and lower pressures?”
Physiologic Basis forUsing Small Tidal Volumes In 1915, Henderson was intrigued by the shallow breathing of panting dogs. He wondered how dogs could pant indefinitely without becoming hypoxic or hypercapnic. So, he designed an experiment to find out.
1915: Henderson Smoke Studies Convection penetrated smoke deeply through tube Effect was called “Flow Streaming”, the sort of flow we try to create with HFJV
1915: Henderson Smoke Studies Diffusion occurred when flow stopped or slowed
Forced Oscillations DuBois and Assoc., 1956Harvard School of Public Health