Duncan Campbell

Retired Anaesthetist

Background: The aim was to produce a compact versatile ventilator for anaesthetists to provide the flexibility of functions required in the operating theatre for paediatric as well as adult patients.
Methods: A pneumatic ventilator was constructed using a venturi jet controlled by a fluidic timer. This allowed great flexibility of control, and after constructing a satisfactory prototype, the manufacture and sales of the ventilator were assigned to Ulco Engineering Pty. Ltd.
Results: The aims were achieved, and over the years numerous modifications were made and alterations for special purposes as for example intensive care or transport use. A disconnect alarm was incorporated, and after several years the initial fluidic controls were changed to more manageable electronics with a visual display. Spin-offs included a horse ventilator, test lungs, a system for measuring airways resistance, a kidney perfusing system, and an anti-DVT system. A new ventilator alarm was designed, and a project for recycling volatile anaesthetics for hospitals. Pulmonary mechanics equations applicable to the arterial system led to a prototype minimally invasive cardiac output monitor, based on the fact that the arterial time constant divided by compliance equals resistance, and this divided into arterial pressure gives cardiac output. Ulco was sold in 2003 and by then over 3,400 ventilators had been made and sold in Australia and overseas.
Conclusions: The absence of mechanical moving parts, precision engineering and attention to detail resulted in a ventilator with long-term reliability, and Ulco succeeding in marketing these ventilators against fierce competition from the multinationals..
Reference: Campbell DI. A new compact, versatile, fluidic controlled ventilator. Anaesth Intensive Care 1976; 4:7-15.