Effects of high-flow nasal cannula and non-invasive ventilation on inspiratory effort in hypercapnic patients with chronic obstructive pulmonary disease: a preliminary study

Abstract

BackgroundNon-invasive ventilation (NIV) is preferred as the initial ventilatory support to treat acute hypercapnic respiratory failure in patients with chronic obstructive pulmonary disease (COPD). High-flow nasal cannula (HFNC) may be an alternative method; however, the effects of HFNC in hypercapnic COPD are not well known. This preliminary study aimed at assessing the physiologic effects of HFNC at different flow rates in hypercapnic COPD and to compare it with NIV.MethodsA prospective physiologic study enrolled 12 hypercapnic COPD patients who had initially required NIV, and were ventilated with HFNC at flow rates increasing from 10 to 50 L/min for 15 min in each step. The primary outcome was the effort to breathe estimated by a simplified esophageal pressure–time product (sPTPes). The other studied variables were respiratory rate, oxygen saturation (SpO2), and transcutaneous CO2 pressure (PtcCO2).ResultsBefore NIV initiation, the median [interquartile range] pH was 7.36 [7.28–7.37] with a PaCO2 of 51 [42–60] mmHg. sPTPes per minute was significantly lower with HFNC at 30 L/min than 10 and 20 L/min (p < 0.001), and did not significantly differ with NIV (median inspiratory/expiratory positive airway pressure of 11 [10–12] and [5–5] cmH2O, respectively). At 50 L/min, sPTPes per minute increased compared to 30 L/min half of the patients. Respiratory rate was lower (p = 0.003) and SpO2 was higher (p = 0.028) with higher flows (30–50 L/min) compared to flow rate of 10 L/min and not different than with NIV. No significant differences in PtcCO2 between NIV and HFNC at different flow rates were observed (p = 0.335).ConclusionsApplying HFNC at 30 L/min for a short duration reduces inspiratory effort in comparison to 10 and 20 L/min, and resulted in similar effect than NIV delivered at modest levels of pressure support in hypercapnic COPD with mild to moderate exacerbation. Higher flow rates reduce respiratory rate but sometimes increase the effort to breathe. Using HFNC at 30 L/min in hypercapnic COPD patients should be further evaluated. Trial registration Thai Clinical Trials Registry, TCTR20160902001. Registered 31 August 2016, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2008.

Impact of High-Flow Nasal Cannula on Arterial Blood Gas Parameters in the Emergency Department

“…In this regard, our study is different from other studies initiating the oxygen support to ARF patients with HFNC on admission. The study conducted by Rittayamai et al explored flow rates' effect on respiratory workload and also found that 30 lt/min had better outcomes than lower flow rates [13]. While other studies showing gradually increased flow rates might be beneficial, due to the retrospective method, we could not specify which patients might benefit from different rates of flow.…”

A narrative review on trans-nasal pulmonary aerosol delivery

“…During exacerbation of COPD, higher than usual patient’s inspiratory flow demand requires an increase of flow setting with HFNC. In 12 hypercapnic patients with COPD initially treated with noninvasive ventilation, Rittayamai and colleagues achieved similar work of breathing with HFNC flow set at 30 L/min [ 65 ]. Discontinuing HFNC to use a facemask significantly increased patients’ breathing efforts [ 66 ].…”

How to ventilate obstructive and asthmatic patients

“…Furthermore, caregiver skill is important to the success of this technique. High-flow nasal cannula may be an alternative method [77,78].…”

“…High-flow nasal cannula may be an alternative method [ 77 , 78 ]. In a recent study conducted in 12 hypercapnic COPD patients with mild to moderate exacerbation who had initially required NIV, applying high-flow nasal cannula at 30 l/min for a short duration reduced inspiratory effort, and resulted in an effect similar to that of NIV delivered at moderate levels of pressure support [ 78 ]. In addition, high-flow nasal cannula is a more comfortable technique than NIV [ 79 , 80 ].…”