Abstract:
Introduction: There are three established respiratory support modalities routinely used in the management of acute respiratory failure (ARF). These include invasive mechanical ventilation (IMV), noninvasive ventilation (NIV) and oxygen therapy. In addition, a new modality called nasal high flow (NHF) has recently been introduced. However, there is little evidence available with which to guide the appropriate application of NHF in a given clinical scenario. Aim The aim of this research was to quantify the experience with NHF in a critical care environment where the therapy is now routinely used for selected patients with ARF. Based on this population and their subsequent therapy outcomes, the broad aim of this research was to begin to provide support for future clinical practice and research. In so doing, begin to understand when, why, how and on whom NHF should be appropriately applied. Methods: In the context of normal clinical practice a prospective, observational study was conducted to describe one patient population receiving NHF. Results: Data were collected and analysed from 120 consecutively enrolled patients, who required NHF for the management of ARF in the course of their critical care admission. Nasal high flow was considered to be successful for 78% of patients, in spite of significant hypoxemia (mean PaO2:FiO2 ratio, 190 [SD56]) and mild to moderate respiratory distress (mean respiratory rate, 20 [SD6]; mean PaCO2 5.5 [SD0.8]; mean pH 7.36 [SD0.06]). The population described was predominantly a post operative cardiac surgical group (52%) but also included patients following vascular (15%) and thoracic (11%) surgery. Nasal high flow was used principally as a step up from traditional forms of oxygen therapy (73%) or as a weaning step down from IMV (18%). Twenty two percent of patients experienced failure of NHF, requiring an escalation of respiratory support to either NIV or IMV. Generally NHF failure was associated with a more unstable physiological status. At baseline, a pH of less than 7.35 should specifically alert the clinical team to the higher probability of NHF failure (p = 0.04). Conclusion In a population of patients experiencing ARF following major surgery, NHF was associated with a high therapy success rate, in spite of significant hypoxemia. The addition of NHF, as a new respiratory support modality appears to be a promising advance the management of patients with ARF.