Effects of different high-flow nasal cannula flow rates on swallowing function

Nutrition during noninvasive respiratory support

PURPOSE OF REVIEW

The use of noninvasive techniques [noninvasive ventilation (NIV) or high flow nasal cannula (HFNC) oxygen therapy] to support oxygenation and/or ventilation in patients with respiratory failure has become widespread, even more so since the coronavirus disease 2019 pandemic. The use of these modalities may impair the patient's ability to eat. "To breath or to eat" may become a dilemma. In this review, we identify the patients at risk of malnutrition that require medical nutritional therapy and understand the mechanisms of function of the devices to better give adapted nutritional indications for noninvasive ventilation or high flow nasal cannula.

RECENT FINDINGS

The Global Leadership Initiative for Malnutrition has been validated in the Intensive Care setting and can be used in patients requiring NIV. Many patients are underfed when receiving noninvasive ventilation therapies. HFNC may impair the swallowing ability and increase dysphagia while NIV may improve the swallowing reflexes. New technology preventing reflux and ensuring enteral feeding efficacy may increase the medical nutrition therapy safety and provide near-target energy and protein provision.

SUMMARY

The patient requiring noninvasive ventilation presents one of the most challenging nutritional challenges. The main steps to improve nutrition administration are to assess nutritional status, evaluate the presence of dysphagia, choose the most adequate tool of respiratory support, and adapt nutritional therapy (oral, enteral, or parenteral) accordingly.

Severe aspiration pneumonia in the elderly

The global population is aging at an unprecedented rate, resulting in a growing and vulnerable elderly population in need of efficient comprehensive healthcare services that include long-term care and skilled nursing facilities. In this context, severe aspiration pneumonia, a condition that carries substantial morbidity, mortality, and financial burden, especially among elderly patients requiring admission to the intensive care unit, has attracted greater concern. Aspiration pneumonia is defined as a pulmonary infection related to aspiration or dysphagia in etiology. Prior episodes of coughing on food or liquid intake, a history of relevant underlying conditions, abnormalities on videofluoroscopy or water swallowing, and gravity-dependent shadow distribution on chest imaging are among the clues that suggest aspiration. Patients with aspiration pneumonia tend to be elderly, frail, and suffering from more comorbidities than those without this condition. Here, we comprehensively address the epidemiology, clinical characteristics, diagnosis, treatment, prevention, and prognosis of severe aspiration community-acquired pneumonia in the elderly to optimize care of this high-risk demographic, enhance outcomes, and minimize the healthcare costs associated with this illness. Emphasizing preventive measures and effective management strategies is vital in ensuring the well-being of our aging population.

Effects of high-flow nasal therapy on swallowing function: a scoping review

Background

High-flow nasal therapy is widely used in patients with respiratory failure in different clinical settings, but the effect of high-flow nasal therapy on respiratory-swallow coordination is unknown. Understanding this relationship is crucial, considering the necessity for patients to maintain adequate nutrition during daytime high-flow nasal therapy. This scoping review aims to synthesise available data on the effects of high-flow nasal therapy flow rates on swallowing function and the possible risk of aspiration during treatment, focusing on knowledge and evidence gaps.

Methods

PubMed, Scopus, Web of Science and Google Scholar databases were searched from inception to 30 May 2023 for studies reporting data on swallowing assessment in healthy adults or patients with acute or chronic respiratory failure receiving high-flow nasal therapy. Data on study design, patients' characteristics and quality outcomes were extracted.

Results

Eight studies were included, four including cohorts of healthy volunteers (n=148) and four including patients with acute or chronic respiratory failure (n=151). Study designs, patient populations and quality outcome measures were heterogeneous. Two studies indicated improvement while four articles showed impairment in swallowing function during high-flow nasal therapy; two studies showed that patients' overall clinical picture and underlying medical conditions influenced swallowing-breathing coordination rather than high-flow nasal therapy per se.

Conclusion

This scoping review found limited and controversial evidence on the impact of high-flow nasal therapy on swallowing function. Remarkably, methods for swallowing function assessment were quite heterogeneous. Additional research is required to test the effect of high-flow nasal therapy on respiratory-swallowing coordination.

Assessment of Swallowing Function in Healthy Adults While Using High-Flow Nasal Cannula

OBJECTIVE

Despite widespread use of high flow nasal cannula (HFNC) for respiratory support, the effect of HFNC on swallowing physiology is poorly understood. Flow rates that permit safe swallowing have not been established. We aim to assess if healthy individuals have diminished swallowing function and safety at high flow rates.

STUDY DESIGN

Repeated measures with planned data collection.

SETTING

Outpatient dysphagia clinic.

METHODS

Swallowing function in a cohort of healthy individuals was assessed using Flexible Endoscopic Evaluation of Swallowing (FEES). Participants' safety of swallowing was assessed with different textures under randomized rates of HFNC (0, 30, 40, 50, and 60 LPM). Swallowing trials included quantities of thin liquids, mildly-thick liquids, and purees. Trials were scored using the Penetration-Aspiration Scale (PAS). Pearson chi-square tests were used to test for correlation between PAS result, flow rate, and consistency across each quantity of material.

RESULTS

Twenty-seven subjects were enrolled. Forty-one percent were male with mean age of 34 years (11 standard deviation). Ninety-nine percent (267/270), 97% (n = 263/270), and 99% (399/405) of 1 sip swallows, 3 sip swallows, and 5 mL swallows, respectively, were safe. There was no significant correlation between swallow safety and flow rate using Pearson Chi-Square test across all consistencies and across all quantities of materials (P > 0.05). Of note, out of all subtrials, the thin liquid, 3 sips trial at 60 LPM, had the largest percent of unsafe swallows (14%).

CONCLUSION

Our results suggest rate of aspiration is not significantly affected by high flow nasal cannula in healthy individuals.

Nutrition practices in hospitalized adults receiving noninvasive forms of respiratory support: A scoping review

The use of noninvasive respiratory support is increasing, with noninvasive ventilation (NIV) and high-flow nasal cannula providing unique barriers to nutrition support. Limited data related to nutrition management for these patients in the intensive care unit (ICU) exist; however, the literature in non-critically ill patients is not well described, and its improvement may help to inform practice within the ICU. Therefore, a scoping review was conducted of MEDLINE, EmCare, and Cumulative Index of Nursing and Allied Health Literature (CINAHL) databases on August 18, 2022, to identify original publications that included adult patients receiving noninvasive respiratory support in a hospital setting with data related to nutrition management. Data were extracted on study design, population, details of respiratory support, and concepts relating to nutrition management (grouped into nutrition screening, assessment, delivery route, intake, and anthropometry). Eleven studies were included, most of which were small (<100 patients), single-center, observational trials in patients receiving NIV only. Five studies reported results related to route of nutrition and nutrition assessment, two on anthropometry, and one each on quantifying intake and nutrition screening; some studies reported multiple parameters. There was a lack of consensus regarding the ideal method for nutrition assessment and route of nutrition. Oral nutrition was the route most frequently reported, yet calorie and protein delivery via this route were inadequate, and barriers to intake included poor appetite, fatigue, and patient cognition. Future research should address barriers pertinent to this population and the impact of nutrition on outcomes.

Pharyngeal oxygen delivery device sustains manikin lung oxygenation longer than high-flow nasal cannula

Purpose

Hypoxemia during a failed airway scenario is life threatening. A dual-lumen pharyngeal oxygen delivery device (PODD) was developed to fit inside a traditional oropharyngeal airway for undisrupted supraglottic oxygenation and gas analysis during laryngoscopy and intubation. We hypothesized that the PODD would provide oxygen as effectively as high-flow nasal cannula (HFNC) while using lower oxygen flow rates.

Methods

We compared oxygen delivery of the PODD to HFNC in a preoxygenated, apneic manikin lung that approximated an adult functional residual capacity. Four arms were studied: HFNC at 20 and 60 liters per minute (LPM) oxygen, PODD at 10 LPM oxygen, and a control arm with no oxygen flow after initial preoxygenation. Five randomized 20-minute trials were performed for each arm (20 trials total). Descriptive statistics and analysis of variance were used with statistical significance of P < 0.05.

Results

Mean oxygen concentrations were statistically different and decreased from 97% as follows: 41 ± 0% for the control, 90 ± 1% for HFNC at 20 LPM, 88 ± 2% for HFNC at 60 LPM, and 97 ± 1% (no change) for the PODD at 10 LPM.

Conclusion

Oxygen delivery with the PODD maintained oxygen concentration longer than HFNC in this manikin model at lower flow rates than HFNC.

Assessing swallowing disorders in adults on high-flow nasal cannula in critical and non-critical care settings. A scoping review protocol

INTRODUCTION

The high-flow nasal cannula (HFNC) has become a widely used respiratory support system, which has proven to be effective in different populations. The facilitation of oral communication and feeding have been described as advantages of this support. Nevertheless, swallowing disorders associated with the use of HFNC have been postulated. However, such evidence is scattered in the literature, not systematically searched, and needs to be adequately summarised. This review aimed to explore the literature, to identify and map the evidence, regarding the frequency and methods of assessment of swallowing disorders in adult HFNC users, in both critical and non-critical units.

MATERIALS AND METHODS

A scoping review will be conducted. A systematic search in MEDLINE (Ovid), Embase (Ovid), CENTRAL, CINAHL (EBSCOhost), and other resources will be conducted. Primary studies, in any language or publication status, assessing the incidence of swallowing disorders in adults with HFNC support will be included. Two reviewers will independently select studies and extract data. Disagreements will be resolved by consensus or a third reviewer. The results will be reported narratively, using tables and figures to support them.

DISCUSSION

Positive end-expiratory pressure generated in the airway by HFNC could impair the proper swallowing performance. Knowing the methodological characteristics, the instruments or scales used to assess the presence of dysphagia, and the results of the studies may contribute to considering swallowing assessment in this population on a routine basis, as well as to guide the conduct of new studies that may respond to less researched areas in this topic.

REGISTRATION

Registration number: INPLASY2022110078.

The effects of flow settings during high-flow nasal cannula support for adult subjects: a systematic review

BACKGROUND

During high-flow nasal cannula (HFNC) therapy, flow plays a crucial role in the physiological effects. However, there is no consensus on the initial flow settings and subsequent titration. Thus, we aimed to systematically synthesize the effects of flows during HFNC treatment.

METHODS

In this systematic review, two investigators independently searched PubMed, Embase, Web of Science, Scopus, and Cochrane for in vitro and in vivo studies investigating the effects of flows in HFNC treatment published in English before July 10, 2022. We excluded studies that investigated the pediatric population (< 18 years) or used only one flow. Two investigators independently extracted the data and assessed the risk of bias. The study protocol was prospectively registered with PROSPERO, CRD42022345419.

RESULTS

In total, 32,543 studies were identified, and 44 were included. In vitro studies evaluated the effects of flow settings on the fraction of inspired oxygen (F_IO₂), positive end-expiratory pressure, and carbon dioxide (CO₂) washout. These effects are flow-dependent and are maximized when the flow exceeds the patient peak inspiratory flow, which varies between patients and disease conditions. In vivo studies report that higher flows result in improved oxygenation and dead space washout and can reduce work of breathing. Higher flows also lead to alveolar overdistention in non-dependent lung regions and patient discomfort. The impact of flows on different patients is largely heterogeneous.

INTERPRETATION

Individualizing flow settings during HFNC treatment is necessary, and titrating flow based on clinical findings like oxygenation, respiratory rates, ROX index, and patient comfort is a pragmatic way forward.