ICU ventilator or anaesthesia ventilator: the differences

On a list of equipment to purchase, "ventilator" can refer to two very different devices: the ventilator built into an anaesthesia workstation, in the operating theatre, and the ICU ventilator, in intensive care. Both deliver a gas mixture into a patient's lungs, but they do not serve the same need, the same environment or the same duration of use. For a buyer or a biomedical engineer who is not a clinician, understanding these differences avoids a costly mistake: acquiring a device that cannot fulfil the role expected in the department.

Two devices, two missions

The anaesthesia workstation supports a surgical procedure. It delivers to the anaesthetised patient a mixture of oxygen, air or nitrous oxide and an anaesthetic agent, while ventilating the patient. Its use is limited to the duration of the procedure; the patient is then woken up and transferred to the recovery room.

The ICU ventilator assists or replaces the breathing of a patient whose condition requires it, sometimes for days or weeks. It delivers no anaesthetic agent: sedation, when needed, is given by other routes, most often by infusion. The two devices are not interchangeable and belong to separate ranges.

In the operating theatre: delivering anaesthesia safely

An anaesthesia workstation is much more than a ventilator. It brings together several functions around the surgical patient:

• Fresh gas dosing and vaporisers, which turn the liquid anaesthetic agent into vapour at the set concentration.
• A rebreathing circuit, in which exhaled gases are cleared of CO2 by an absorber and then reused, making low fresh gas flow possible.
• Analysis of inspired and expired gases: oxygen, carbon dioxide and anaesthetic agents.
• Connection to the anaesthetic gas scavenging system of the operating room, to protect the team.

The built-in ventilator offers controlled and assisted modes suited to anaesthesia. For example, the manufacturer's brochure for the WATO EX-65 workstation states a monitored tidal volume of 0 to 3 000 mL, and its multi-gas module automatically identifies the anaesthetic agents.

In intensive care: ventilating over time

In the intensive care unit (ICU), ventilation is a prolonged treatment, adjusted as the patient's condition evolves. The device must run without interruption, support the patient's own breathing efforts and prepare for the moment when the patient can breathe unaided. The expectations include:

• Invasive ventilation modes, via an endotracheal tube or tracheostomy, and often non-invasive modes, via a mask.
• Weaning support tools, to assess the patient's ability to resume spontaneous breathing.
• Recording of trends and alarms over several days, available to the team.
• Depending on the model, a built-in turbine and a battery for intra-hospital transport, for example to imaging.

The SV300 illustrates this last point: its built-in turbine allows it to operate without a central medical air supply, and its brochure states a maximum turbine flow of 210 L/min. The patient population also matters: for patient types, the SV600 brochure states "Adult, paediatric, neonatal". A neonatal unit is not equipped in the same way as an adult intensive care unit.

Humidification, a requirement specific to intensive care

In an intubated patient, gases bypass the nose and upper airways, which normally warm and humidify inspired air. Because medical gases are dry, prolonged ventilation without humidification dries out the airways and secretions. In intensive care, the ventilator is therefore combined with a heated humidifier, such as the MR850 humidifier from Fisher & Paykel, or with heat and moisture exchange filters, according to the department's protocols. In the operating theatre, the rebreathing circuit retains part of the heat and moisture of exhaled gases, and ventilation is shorter: a heated humidifier is generally not part of the basic equipment there.

The comparison at a glance

The main differences, criterion by criterion:

• Use: general anaesthesia during a procedure, versus respiratory support for a patient in distress or under prolonged sedation.
• Duration: the length of a procedure in the operating theatre, versus days or weeks in intensive care.
• Anaesthetic agents: delivered and measured by the anaesthesia workstation, absent from the ICU ventilator.
• Circuit: rebreathing with a CO2 absorber in anaesthesia, no rebreathing in intensive care.
• Patient monitoring: analysis of gases and anaesthetic agents in the operating theatre, tracking of respiratory mechanics and trends over time in intensive care, alongside the patient monitor.
• Humidification: rarely active in the operating theatre, heated humidifier or exchange filter in intensive care.

Key points for purchasing

The choice starts with the department that will use the device, not with the datasheet. Before consulting suppliers, a few questions clarify the need:

• Where will the device be used: operating room, intensive care, intra-hospital transport?
• Which patients will be treated: adults, children, newborns?
• What resources does the site have: medical gases, central medical air, anaesthetic gas scavenging?
• Which equipment must it work with: patient monitors, central monitoring station, humidifiers?

These answers form the basis of sound specifications. Medico Medline, exclusive distributor of Mindray in Algeria, offers both families: the workstations of the anaesthesia range and the ventilators of the intensive care range. Datasheets can be downloaded from each product page, and a quote request can be sent online for the configurations under consideration.