Volume preset ventilators

If flow is measured and used to deliver a preset volume, then a ventilator is considered to be a flow controller (1). In most of the cases, volume preset ventilation is provided by ventilators that actually measure flow and use flow over time to deliver a preset volume. These machines maintain an approximately constant volume in the face of varying lung mechanics. The most common flow-controlled ventilators are listed in Table 2. As indicated in the table, most of these machines can also provide pressure ventilation. 

Early type 2 ventilation failure requires a life-support strategy to clear the airway and start ventilation. The use of a volume preset ventilator is important to ensure the delivery of an adequate tidal volume since there may be decreased compliance (V/P) and increased airway resistance with the development of type 2 respiratory failure. 

Regardless of whether a ventilator uses positive pressure or negative pressure, the trans-pulmonary pressure gradient determines the tidal volume. A ventilator that is a pressure controller delivers a preset pressure and this variable is unaffected by changes in limg compliance or resistance. A positive pressure ventilator applies pressure inside the chest to expand it using a noninvasive interface, or an artificial airway. 

Care providers play a crucial role in HMV in most countries. The Eurovent survey showed that, in Europe, ventilator servicing, such as maintenance, repair, delivery of spare parts, and regular surveillance, was carried out mainly by private companies. In some countries like Sweden, ventilator servicing was carried out directly by hospitals. The interaction between servicing companies and the prescriber was poor (14). Another problem was the variety of ventilators that exist in the market, with more than 70 models in Europe for 70% preset pressure and 30% volume ventilation. 

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