Acute respiratory failure (ARF) is treated by mechanical ventilation (MV) to ‘gain time’, such as, when the cause of ARF is reversibile, medical treatment can maximize lung function while reversing the precipitating cause. Mechanical ventilation works by unloading the respiratory muscles, increasing alveolar ventilation, improving dyspnea, reducing respiratory rate and finally improving arterial oxygenation, hypercapnia and related respiratory acidosis Citation[1]. The historic way to apply MV is through an endotracheal tube, which is associated with complications related to performance of endotracheal intubation, baro/volu-trauma and loss of airway defense mechanisms. Other complications may also be associated with extubation or long-term tracheostomy Citation[2].
Noninvasive ventilation (NIV) avoids most of these complications, while performing with the same degree of effectiveness as invasive MV Citation[3,4]. The widespread use of NIV has reduced the incidence of ventilator-associated pneumonia (VAP) and other hospital-acquired infections by saving airway defense mechanisms and reducing the need for invasive monitoring Citation[5]. In contrast to invasive MV, NIV can be applied intermittently, allowing patients to eat, drink, cough and communicate, reducing the need for sedation and saving nursing costs, while allowing treatment with physiotherapy Citation[6].
This modality represents a relevant progress in the treatment of acute and acute on chronic respiratory failure in the past two decades and is increasingly being used all over the world Citation[7–9]. A literature search of published research from 1966 to 13 February 2012 (key word: noninvasive ventilation; Source: PubMed) shows 3874 (726 reviews) references on the topic.
Several prospective, randomized, controlled studies, systematic reviews and meta-analyses show a good level of evidence for the clinical effectiveness of NIV in the treatment of acute on chronic respiratory failure due to acute exacerbations of chronic obstructive pulmonary disease (COPD). Indeed, NIV has been proposed as the first-line ventilatory strategy in this condition, with different timing and location according to the level of ARF severity.
As a consequence, this increased familiarity and greater availability of NIV leads to its wider use, including, on occassion, patients outside of the indications of randomized clinical trials. Furthermore NIV is being increasingly used in several sites of performance Citation[9,10]. Despite the intensive care unit (ICU) being the safest location to perform NIV, the very common shortage of ICU beds and the increasing indications to NIV has also led to its application outside of the ICU, including the emergency department, step-down units, medical wards and even prior to hospital admission Citation[11–16]. Furthermore, some hospitals have created special nursing units, commonly located next to the ICU, or ‘travelling teams’ to facilitate NIV use Citation[17]. This attitude can be potentially dangerous – indeed it should be made clear that NIV is not a panacea nor the ‘poor man’s’ MV technique; it cannot replace endotracheal intubation in all circumstances Citation[3].
One of the main determinants of NIV success is location. The site of NIV performance may determine the success of NIV depending on the treated patient and monitoring resources. Enthusiasm for NIV may lead the neophytes of this technique to apply the modality to the wrong patient in the wrong setting. It has been shown that NIV can be safely applied in the general ward to COPD patients suffering from mild acute exacerbation with mild respiratory acidosis (pH >7.30) Citation[16]. Furthermore, a case series reported the effectiveness of this modality in patients with moderate-to-severe ARF (pH >7.25) as a result of acute exacerbations of COPD in general ward settings Citation[18]. This should not justify the routine use of NIV in the general ward even in the most severe conditions. In fact treating a patient with severe hypoxemia with or without hypercapnia could be dangerous in a general ward, whereas it is safer in a monitored high-technology setting, such as in an ICU or at least in a monitoring unit provided prompt intubation is available. In other words, the selection of patients must take into account the location available in which to perform NIV.
The strategies to apply NIV may be different among different institutions Citation[19]. Wherever NIV is applied, close monitoring is mandatory, especially during the initial period. The main concepts for adequate monitoring and treatment of patients under NIV can be summarized by:
• Strict nurse supervision of patients’ respiratory and neurological conditions: this is clearly not possible in a general ward without dedicated personnel;
• Noninvasive monitoring of arterial oxygenation by pulsometry, electrocardiogram and blood pressure.
Therefore, the choice of monitoring and devices is crucial to NIV location, which can actually determine outcome. An even more important factor in choosing location is the training of the care team. Ability to perform NIV improves with use. It has been reported that, with increasing experience, the care team is able to treat, with the same high NIV success rate, increasing severity of episodes of ARF Citation[20]. Therefore, increased experience with NIV is a crucial factor in improving patient survival rates and decreasing hospital-acquired infections in the ICU Citation[21].
A final point in the choice of location for NIV is the expected outcome in the individual patient. A very recent study shows that patients who fail NIV and subsequently require endotracheal intubation experience significantly higher mortality than patients placed on invasive MV from the outset and experience the longest and most expensive hospitalizations for COPD exacerbations Citation[9]. The author concludes that healthcare providers should continue to be aggressive with the use of NIV but should intensively monitor sick patients, and intervene early in the absence of improvement. This can only be done in a safer location than a general ward, as the prompt availability of endotracheal intubation is required.
On the other hand, the caregiver in charge must carefully examine whether transition to endotracheal intubation is ‘ethical’ in a patient with a poor prognosis who has just failed NIV or whether it is better to proceed with ‘palliative’ NIV, even in a less equipped location. This may be the case for the use of NIV in palliative care Citation[22,23].
Financial & competing interests disclosure
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
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