Breakthrough Allows Patients to Control Ventilator

A breakthrough in ventilation therapy enables patients to control the ventilator with the respiratory center in their brain.

Called NAVA (neurally adjusted ventilatory assist), the new approach to mechanical ventilation is based on the patient's neural respiratory output. Signals from the respiratory control center in the brain are transmitted through the phrenic nerve to the diaphragm, where a catheter captures the electrical activity (Edi) and feeds it to the ventilator. NAVA responds by providing the requested level of ventilatory support to the patient. As the ventilator and diaphragm work with the same signal, the coupling between the two is virtually instantaneous. In contrast, conventional mechanical ventilators sense patient effort either by a drop in airway pressure or a reversal in flow.

Benefits of NAVA include improved synchrony between the patient and the ventilator, lung protection through avoidance of over- or under-assistance of the patient, and enhanced patient comfort, since the improved synchrony helps minimize patient discomfort and agitation while at the same time promoting spontaneous breathing.

The Edi signal can be used as a unique monitoring tool providing information on respiratory drive, volume requirements, and effects of ventilatory settings. It can also be used to gain an indication for sedation or weaning and to support the decisions of medical staff concerning unloading or extubation.

"NAVA is a completely new mode of mechanical ventilation where the ventilator is controlled by the patient's respiratory center on a breath-by-breath basis,” said Dr. Christer Sinderby, Ph.D., a researcher in the department of Critical Care at St. Michael's Hospital (Toronto, Canada). "In addition to being a distinct mode of ventilation, NAVA also enables a complete evaluation of the neural respiratory control thanks to the electrical activity of the diaphragm.”

The NAVA function is available on the Servo-i ventilator of Maquet Critical Care (Solna, Sweden). The only equipment required in addition to the Servo-i ventilator is NAVA software, an Edi module, and an Edi catheter. Maquet notes that current Servo-i users can upgrade an existing unit with the NAVA function. The new NAVA function was introduced by Maquet at the annual meeting of the European Society of Intensive Care Medicine (ESICM) in Barcelona (Spain) in September 2006.


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