The starting rate for high‐flow nasal cannula oxygen therapy in infants with bronchiolitis: Is clinical judgment enough?

Abstract

Objectives: To determine whether in infants with bronchiolitis admitted to a pediatric intensive care unit (PICU) the starting rate for high-flow nasal cannula (HFNC) therapy set by the attending physicians upon clinical judgment meets patients' peak inspiratory flow (PIF) demands and how it influences respiratory mechanics and breathing effort.Methodology: We simultaneously obtained respiratory flow and esophageal pressure data from 31 young infants with moderate-to-severe bronchiolitis before and after setting the HFNC rate at 1 L/kg/min (HFNC-1), 2 L/kg/min (HFNC-2) or upon clinical judgment and compared data for PIF, respiratory mechanics, and breathing effort.Results: Before HFNC oxygen therapy started, 16 (65%) infants had a PIF less than 1 L/kg/min (normal-PIF) and 15 (45%) had a PIF more than or equal to 1 L/kg/min (high-PIF). Normal-PIF-infants had higher airway resistance (p < .001) and breathing effort indexes (e.g., pressure rate product per min [PTP/min], p = .028) than high-PIF-infants. Starting the HFNC rate upon clinical judgment (1.20-2.05 L/kg/min) met all infants' PIFs. In normal-PIF-infants, the clinically judged flow rate increased PIF (p = .081) and tidal volume (p = .029), reduced airway resistance (p = .011), and intrinsic positive end-expiratory pressure (p = .041), whereas, in both high-PIF and normal-PIF infants, it decreased respiratory rate (p < .001) and indexes of breathing effort such as PTP/min (in normal-PIF infants, p = .004; in high-PIF infants, p = .001).The 2 L/kg/min but not 1 L/kg/min rate induced similar effects. Conclusions:The wide PIF distribution in our PICU population of infants with bronchiolitis suggests two disease phenotypes whose therapeutic options might differ. An initial flow rate of nearly 2 L/kg/min meets patients' flow demands and improves respiratory mechanics and breathing effort.

The effects of flow settings during high-flow nasal cannula oxygen therapy for neonates and young children

“…Consequently, 44 studies were included: 15 were in vitro studies [ 12 – 26 ], two combined in vitro and in vivo studies were conducted on neonates [ 27 , 28 ] and 27 were clinical studies [ 6 – 8 , 29 – 52 ]. In the clinical studies ( supplementary table S1 ), 14 were conducted on neonates [ 29 – 41 , 51 ] including preterm infants with [ 29 , 31 , 34 , 35 , 37 , 38 , 51 ] or without [ 30 , 32 , 33 , 36 , 39 – 41 ] lung disease, while 13 focused on paediatric patients with bronchiolitis [ 6 – 8 , 44 , 46 – 48 , 50 , 52 ] or requiring HFNC for various reasons [ 42 , 43 , 45 , 49 ], with most the patients younger than 2 years. Four of these studies were RCTs [ 48 – 51 ], and ten were randomised crossover studies [ 31 , 33 , 34 , 37 , 39 – 41 , 43 , 45 , 46 ].…”

“…In the two studies involving infants with bronchiolitis, an increase in flow was associated with an improvement in the patient's S pO 2 / F IO 2 ratio ( supplementary table S4 ) [ 7 , 8 ]. When the flow was increased from 0.5 to 2 L·kg −1 ·min −1 [ 44 , 46 ], no significant differences were observed in V T and minute ventilation, as assessed by respiratory inductance plethysmography [ 45 ], pneumotachography [ 44 ] or electric impedance tomography [ 46 ]. Moreover, when flow was increased from 0.4 to 2 L·kg −1 ·min −1 , a reduction in respiratory rate was observed in six studies ( figure 3a ) [ 6 , 8 , 43 – 46 ], except for the study conducted by N ascimento et al [ 7 ], in which no significant differences in respiratory rate were observed across flows of 0.5–2 L·kg −1 ·min −1 when using the Vapotherm device.…”

“…In the aforementioned five studies [ 6 , 8 , 43 , 46 , 47 ] that reported pharyngeal pressure or P ese, four measured PRP ( figure 3c ) [ 8 , 43 , 46 ] or pressure-time product ( supplementary table S7 ) [ 6 ] as surrogate markers of WOB, and all reported a reduction in WOB with increasing flows. Additionally, P apoff et al [ 44 ] measured PRP and pressure-time product, and both values decreased with increasing flows. W eiler et al [ 42 ] also reported a 21% reduction in PRP as the flow increased from 0.5 to 2 L·kg −1 ·min −1 .…”

Is implementation of a hospital pathway for high‐flow nasal cannula initiation and weaning associated with reduced high‐flow duration in bronchiolitis?

“…This finding is in contrast to several studies cautioning providers about the questionable impact of higher flow rates, suggesting prolonged weaning. 27,28 Higher initial maximum flow rates fit with observational and physiological studies that suggest HFNC flow rates approximating 2 L/kg/min may be necessary to unload respiratory muscles, improve work of breathing, or generate positive airway pressure in children with bronchiolitis [29][30][31][32][33][34] and several studies of protocols with higher flow rates have demonstrated some favorable outcomes. 22,24 Our findings also support practice standardization and weaning guidance for mitigating prolonged HFNC duration.…”

UPDATE - 2022 Italian guidelines on the management of bronchiolitis in infants

“…It has been reported that an initial high-flow rate of nearly 2 L/kg/min meets patients' flow demands and improves respiratory mechanics and breathing effort [61]. A prospective, observational and analytical study showed that an initial flow of 15 L/min is associated with a faster improvement of respiratory rate and a lower treatment failure rate [62].…”