Noninvasive ventilation (NIV) is contraindicated or at least not recommended in patients with altered consciousness syndrome (ACS) given to the poor compliance of confused/agitated patients, difficult management of accumulated secretion in depressed cough reflex, and risk of aspirative pneumonia in absence of airways protection.

Conventional mechanical ventilation (CMV) via endotracheal intubation (ETI) has been usually considered as the "golden standard" ventilator treatment in ACS. However, the possibility of avoiding ETI-related life-threatening complications by means of NIV, especially in fragile, older patients with multiple comorbidities, is an appealing option.

The available published data dealing with the use of NIV in ACS were obtained in patients with hypercapnic encephalopathy complicating severe exacerbations of COPD. In this clinical scenario, an initial cautious NIV trial may be attempted as long as there are no other contraindications and the technique is provided by experienced caregivers in a closely monitored setting where ETI is always readily available. The concomitant use of techniques for removing secretion and/or controlled analgo-sedation performed by expert teams may be considered in highly selected cases.

The purpose of this paper is to review rationale, clinical feasibility, advantages and risks correlated with the use of NIV in ACS.