Hamilton reducing risks in transport ventilation

Swiss Air-Rescue (Rega)

When Swiss Air-Rescue (Rega) was looking to replace the transport ventilators in its jets, the idea was to find a ventilator that is capable of continuing the care provided bedside during air transport. Evaluation of the transport ventilators currently available on the market did not meet their requirements – considering that The transport of patients requiring mechanical ventilation bears considerable risks. A change of equipment as well as any change in the patient’s position can affect the patient’s condition. Rega looked for advanced ventilation technology on a stable transport platform being aware of the potential compilations.


During the transport, hypoxemia may occur as a consequence of the inability to reproduce bedside ventilator settings adequately. Elevated O2 concentration may potentially mask deterioration in lung function and can contribute to absorption atelectases. Hyperventilation is a common complication associated with the poor control of minute ventilation by most of the portable ventilators.

Hyperventilation increases intrathoracic pressure, produces air trapping, reduces cardiac output, shifts the oxyhemoglobin dissociation curve to the left hindering oxygen unloading, and causes cerebral and myocardial vasoconstriction. These combined effects may affect patient outcome adversely (Tobin, 2006). The development of dedicated transport ventilators started at the beginning of last century – independent of the ICU ventilators. The transport devices needed to  be rugged, lightweight, reliable and operate from battery power or from the pressure of the oxygen. A basic transport ventilator supplies mechanical ventilation at a specified rate and pressure and offers minimal monitoring and alarm capabilities. Newer devices are more sophisticated and allow for synchronization and (limited) O 2 therapy.


Finally, Rega chose to equip its ambulance jets with the HAMILTON-T1. Hamilton Medical, a Swiss company that is specialized in critical care ventilators, had used a rather different approach when designing the ventilator: Instead of taking a transport ventilator and adding ICU features, Hamilton Medical designed a fully equipped ICU ventilator and made it shock resistant, water-protected and light-weight. In the final phase of the development, a close partnership between Rega and Hamilton Medical allowed the ventilation specialists to tailor the HAMILTONT1 exactly to the needs of mechanical ventilation during air ambulance transports.

A fully-fledged iCU ventilator is “airborne”

The HAMILTON-T1 ventilator has a powerful turbine integrated that delivers up to 210 l/min flow and thus guaranteeing high performance, also during non-invasive ventilation. IntelliTrig – a unique feature of the HAMILTON- T1 – automatically adjusts inspiratory and expiratory flow trigger for a perfect synchronization between the patient and the ventilator. Besides advanced ventilation features like a FiO2 setting between 21% and 100%, biphasic modes DuoPAP and APRV, trends and loops, the HAMILTON-T1 includes the Dynamic Lung visualizing the patient’s lung conditions and Adaptive Support Ventilation (ASV). ASV relies on closed loop regulation of settings in response to changes in respiratory mechanics and spontaneous breathing. Once a target minute volume is entered by the clinician using a percent Minute Volume setting, ASV automatically determines a target tidal volume (VT) and respiratory rate combination based on the minimum work of breathing principle. The advantages of ASV have been shown in various studies. During transport, where conditions are even more difficult, this ventilation mode helps the medical team to optimally ventilate the patient with less user interactions and fewer alarms. The team can focus on on other important tasks.

Case report:

Transfer of a 9-year-old boy with open chest

vent3The first mission with the HAMILTON-T1 was carried out in Germany in October 2011. The patient, a 9-year-old boy with a history of cardiac arrest of unclear origin (and therefore often in need of resuscitation), was waiting in Düsseldorf for air ambulance transport to Berlin. He developed an acute respiratory infection and, as a result, a cardiac insufficiency, which was to be treated by the implantation of a ventricular-assist device – a procedure which had to be perf ormed in Berlin. At the takeover in Düsseldorf, the Rega team was confronted with the boy having an open chest and being connected to an extracorporeal membranoxygenation device (ECMO).

Ventilation on a conventional ICU ventilator had been demanding. The patient was disconnected and reconnected to the HAMILTON-T1. The height of the patient was entered as basic setting and the mode ASV selected. Within a minute, the patient was showing normal ventilation parameters for the circumstances. During the entire flight, the ventilator HAMILTON-T1 adapted perfectly to the various changes in environmental and patient conditions and maintained a stable respiratory performance. Throughout the transfer with ongoing ECMO treatment, the Rega team could take care of the patient without the need to constantly check and adjust the ventilator settings. Upon arrival in Berlin, the patient was disconnected from the HAMILTON-T1 and reconnected to a conventional ICU ventilator. Another demanding transport was completed successfully and the Rega team – satisfied and quite impressed by the new device – headed back to their base in Zurich.

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