Noninvasive Oxygenation in Patients with Acute Respiratory Failure: Current Perspectives

Abstract

Purpose of Review High-flow nasal oxygen and noninvasive ventilation are two alternative strategies to standard oxygen in the management of acute respiratory failure. Discussion Although high-flow nasal oxygen has gained major popularity in ICUs due to its simplicity of application, good comfort for patients, efficiency in improving oxygenation and promising results in patients with acute hypoxemic respiratory failure, further large clinical trials are needed to confirm its superiority over standard oxygen. Non-invasive ventilation may have deleterious effects, especially in patients exerting strong inspiratory efforts, and no current recommendations support its use in this setting. Protective non-invasive ventilation using higher levels of positive-end expiratory pressure, more prolonged sessions and other interfaces such as the helmet may have beneficial physiological effects leading to it being proposed as alternative to high-flow nasal oxygen in acute hypoxemic respiratory failure. By contrast, non-invasive ventilation is the first-line strategy of oxygenation in patients with acute exacerbation of chronic lung disease, while high-flow nasal oxygen could be an alternative to non-invasive ventilation after partial reversal of respiratory acidosis. Questions remain about the target populations and non-invasive oxygen strategy representing the best alternative to standard oxygen in acute hypoxemic respiratory failure. As concerns acute on-chronic-respiratory failure, the place of high-flow nasal oxygen remains to be evaluated.

Improved Arterial Oxygenation by High Flow Nasal Cannula Oxygen Therapy in Older Patients with Severe Respiratory Failure in a Non-intensive Hospital Ward

“…In conclusion, we observed that HFNC -used as escalation therapy for untreatable hypoxia during COT or NIV/CPAP -significantly increased arterial oxygenation without causing hypercapnia in ARF patients admitted to a geriatric non-intensive ward. HFNC is better tolerated than NIV, assures continuous ventilation without interruptions, does not compromise normal nutrition and oral hydration and allows patients to continue communicating with others, thereby reducing the risk of dehydration, malnutrition and delirium [3][4][5]18]. It should also be mentioned that, compared to NIV, HFNC decreased inspiratory effort in type 1 ARF, thus mitigating the risk of self-inflicted lung injury [5], and this may have contributed to the lower mortality observed during HFNC [4].…”

“…High flow nasal cannula oxygen therapy (HFNC) is another type of non-invasive respiratory support [3][4][5]. A very high flow of heated and humidified gas mixture (oxygen plus room air) is administered through soft nasal prongs.…”

“…The fraction of inspired oxygen (FiO2), i.e. the concentration of oxygen in the gas mixture, can be titrated from 21% (only room air) up to 100% [3][4][5]. The high flow generates a continuous positive pressure in the airways (about 5 cmH2O at a flow of 60 l/min with closed patient's mouth) which facilitates alveolar recruitment.…”

“…The high flow generates a continuous positive pressure in the airways (about 5 cmH2O at a flow of 60 l/min with closed patient's mouth) which facilitates alveolar recruitment. In addition, a flow-dependent wash-out of expired gas in the dead space reduces carbon dioxide (CO2), while the muco-ciliary clearance is improved by the heated and humidified gas [3][4][5]. HFNC is mainly used to treat type 1 ARF (hypoxaemia without hypercapnia), while the co-existence of hypercapnia (type 2 ARF) often 2 requests the application of NIV for providing higher mean airways pressures and unloading respiratory muscles [3][4][5].…”

“…In addition, a flow-dependent wash-out of expired gas in the dead space reduces carbon dioxide (CO2), while the muco-ciliary clearance is improved by the heated and humidified gas [3][4][5]. HFNC is mainly used to treat type 1 ARF (hypoxaemia without hypercapnia), while the co-existence of hypercapnia (type 2 ARF) often 2 requests the application of NIV for providing higher mean airways pressures and unloading respiratory muscles [3][4][5]. In type 1 ARF, HFNC performs better that COT, mostly reducing intubation rate, and results at least as effective as NIV, with some evidence of lower mortality with HFNC compared to NIV [4].…”