The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children

Objectives Trans‐nasal pulmonary aerosol delivery for infants and toddlers has recently gained popularity, however, the reported lung deposition is low. We aimed to investigate the influential factors to improve the delivery. Methods Anatomic airway manikins simulating infant (5 kg) and toddler (15 kg) with collecting filter connected the trachea and breath simulator, were set to represent quiet and distressed breathing. Nasal cannula flow was set at 0.125, 0.25, 0.5, 1, and 2 L/kg/min. A mesh nebulizer (Aerogen) was placed at the inlet of humidifier (Fisher & Paykel) and proximal to patient. Albuterol (5 mg in 1 mL) was nebulized for each condition (n = 3). Drug was eluted from the filter and assayed with UV spectrophotometry (276 nm). Results Inhaled dose was higher with nebulizer placed at the inlet of humidifier than proximal to patient in all settings, except the infant model at low gas flow settings (0.125 and 0.25 L/kg/min). When nebulizer was placed at the inlet of humidifier, inhaled dose was higher when gas flow was below patient's inspiratory flow than when gas flow exceeded patient's inspiratory flow (8.77 ± 3.84 vs 2.16 ± 1.29%, P < 0.001); aerosol deposition increased as gas flow decreased, with greatest deposition at gas flow of 0.25 L/kg/min (11.29 ± 2.15%). A multiple linear regression identified gas flow as the primary predictor of aerosol delivery. Conclusions Trans‐nasal pulmonary aerosol delivery was significantly improved when gas flow was below patient's inspiratory flow, aerosol deposition increased with decreased nasal cannula flow, with greatest deposition at 0.25 L/kg/min.

Section: Discussionmentioning

confidence: 99%

Decrease the flow setting to improve trans‐nasal pulmonary aerosol delivery via “high‐flow nasal cannula” to infants and toddlers

Gong²,

Ari

et al. 2019

“…Although previously the 1‐L·kg·min −1 flow rate or 4 to 8 L/min flow rate was frequently used in patients with bronchiolitis, currently most centers choose the 2‐L·kg·min −1 flow rate . But this modification is based on only a few physiological studies, and there still has been no satisfactory clinical data to determine the optimal flow rate required for clinical benefit …”

Section: Discussionmentioning

confidence: 99%

Comparison of heated humidiﬁed high‐flow nasal cannula flow rates (1‐L·kg·min⁻¹ vs 2‐L·kg·min⁻¹) in the management of acute bronchiolitis

Yurtseven

Turan

Erseven

et al. 2019

Objective We aimed to compare the heated humidiﬁed high‐ﬂow nasal cannula (HHHFNC) flow rate of 1‐L·kg·min−1 (1 L) with 2‐L·kg·min −1 (2 L) in patients with severe bronchiolitis presenting to the pediatric emergency department. Study design We performed a study in which all patients were allocated to receive these two flow rates. The primary outcome was admitted as treatment failure, which was defined as a clinical escalation in respiratory status. Secondary outcomes covered a decrease of respiratory rate (RR), heart rate (HR), the clinical respiratory score (CRS), rise of peripheral capillary oxygen saturation (SpO2), and rates of weaning, intubation, and intensive care unit (ICU) admission. Results One hundred and sixty‐eight cases (88 received the 1‐L flow rate and 80, the 2‐L flow rate) were included in the analyses. Treatment failure was 11.4% (10 of 88) in the 1‐L group, and 10% (8 of 80) in the 2‐L group (P = .775). Significant variation in the intubation rate or the ICU admission rate was not determined. At the 2nd hour, the rate of weaning (53.4% vs 35%; P = .017), the falling down of the CRS (−2.1 vs −1.5; P < .001), RR (−15.2 vs −11.8; P < .001), and HR (− 24.8 vs − 21.2; P < .001), and the increase of SpO 2 (4.8 vs 3.6; P < .001) were significantly more evident in the 1‐L group. Conclusion HHHFNC with the 1‐L·kg·min−1 flow rate, which provides a more frequent earlier effect, reached therapy success as high as the 2‐L·kg·min −1 flow rate in patients with severe acute bronchiolitis.

“…Decreasing gas flow to increase inhaled dose via HFNC might be of benefit in the efficient delivery of a short‐acting β‐agonist, but one might have concerns that the flow reduction might influence work of breathing. Weiler et al found patients' work of breathing was reduced by 20% when gas flow increased from 0.5 L/kg/min to 1.5‐2 L/kg/min. However, asthmatic patients might benefit more from effective bronchodilator delivery than the 20% improvement on work of breathing benefited from a higher flow rate.…”

Section: Discussionmentioning

confidence: 99%

“…The observation that toddlers better tolerate nasal oxygen administration than mask has led to the in‐line placement of nebulizers with high‐flow nasal cannula (HFNC) devices for transnasal pulmonary delivery . This approach combines benefits of patient's acceptance to receive aerosolized medication for extended dosing periods with the effects of heated humidified gas at the high‐flow rate, which has been shown to reduce the patients' work of breathing and improve ventilation . Vibrating mesh nebulizer (VMN) is preferred during aerosol delivery via HFNC due to no gas required to generate an aerosol, negligible residual volume, and quiet operation.…”

Section: Introductionmentioning

confidence: 99%

“…The gas flow rate has been inversely correlated to aerosol delivery efficiency via HFNC . However, reducing flow for prolonged periods may impact oxygenation and work of breathing . We hypothesize that delivery of a unit dose of high‐concentrated albuterol in a small total volume (1‐2 mL), requiring 3 to 6 minutes could deliver a similar or higher inhaled dose than the same administered dose via infusion pump over a longer period of time.…”

Section: Introductionmentioning

confidence: 99%

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In vitro comparison of unit dose vs infusion pump administration of albuterol via high‐flow nasal cannula in toddlers

Fink

2019

Objectives Transnasal pulmonary aerosol delivery using high‐flow nasal cannula (HFNC) devices has become a popular route of aerosol administration in toddlers. Clinically, albuterol is administered using an infusion pump or unit doses. However, little evidence is available to compare the two administration strategies. Methods A toddler manikin (15 kg) with appropriate anatomic airway was connected with collecting filter to a simulator of distressed breathing. HFNC device with mesh nebulizer placed at the inlet of a humidifier at 37°C, with the gas flow set at 25 and 3.75 L/min. Five milligrams of albuterol was delivered in all experiments. With infusion pump administration, albuterol concentrations of 5 and 1 mg/mL were delivered at 4 and 20 mL/hr for 15 minutes. With unit dose administration, 1 mL (5 mg/mL) and 2 mL (2.5 mg/mL) of albuterol were nebulized. Additional tests with mouth open and nebulizers via mask were using 5 mg/1 mL for mesh nebulizer and 5 mg/3 mL for jet nebulizer (n = 3). The drug was eluted from the filter and assayed with UV spectrophotometry (276 nm). Results The inhaled dose was higher with unit dose than infusion pump administration with gas flows of 25 L/min (2.66 ± 0.38 vs 1.16 ± 0.28%; P = .004) and 3.75 L/min (10.51 ± 1.29 vs 8.58 ± 0.68%; P = .025). During unit dose administration, compared with closed‐mouth breathing, open‐mouth breathing generated a higher inhaled dose at 3.75 L/min and lower inhaled dose at 25 L/min. Compared to the nebulizers via mask with both open and closed‐mouth breathing, nebulization via HFNC at 3.75 L/min generated greater inhaled dose, while HFNC at 25 L/min generated lower inhaled dose. Conclusions During transnasal aerosol delivery, the inhaled dose was higher with medication administrated using unit dose than using an infusion pump.