Place of high-flow nasal oxygen in nonoperating room anesthesia.

PURPOSE OF REVIEW: This article aims to assess the utility of high-flow nasal oxygen (HFNO) therapy in nonoperating room anesthesia (NORA) settings. RECENT FINDINGS: The number of procedural interventions under deep sedation in NORA is still increasing. Administration of oxygen is recommended to prevent hypoxemia and is usually delivered with standard oxygen through nasal cannula or a face mask. HFNO is a simple alternative with a high warmed humidified flow (ranging from 30 to 70 l/min) with a precise fraction inspired of oxygen (ranging from 21 to 100%). Compared to standard oxygen, HFNO has demonstrated efficacy in reducing the incidence of hypoxemia and the need for airway maneuvers. Research on HFNO has primarily focused on its application in gastrointestinal endoscopy procedures. Yet, it has also shown promising results in various other procedural interventions including bronchoscopy, cardiology, and endovascular procedures. However, the adoption of HFNO prompted considerations regarding cost-effectiveness and environmental impact. SUMMARY: HFNO emerges as a compelling alternative to conventional oxygen delivery methods for preventing hypoxemia during procedural interventions in NORA. However, its utilization should be reserved for patients at moderate-to-high risk to mitigate the impact of cost and environmental factors.

Exploring Heterogeneity in Cost-Effectiveness Using Machine Learning Methods: A Case Study Using the FIRST-ABC Trial.

OBJECTIVE: The aim of this study was to explore heterogeneity in the cost-effectiveness of high-flow nasal cannula (HFNC) therapy compared with continuous positive airway pressure (CPAP) in children following extubation. DESIGN: Using data from the FIRST-line support for Assistance in Breathing in Children (FIRST-ABC) trial, we explore heterogeneity at the individual and subgroup levels using a causal forest approach, alongside a seemingly unrelated regression (SUR) approach for comparison. SETTINGS: FIRST-ABC is a noninferiority randomized controlled trial (ISRCTN60048867) including children in UK paediatric intensive care units, which compared HFNC with CPAP as the first-line mode of noninvasive respiratory support. PATIENTS: In the step-down FIRST-ABC, 600 children clinically assessed to require noninvasive respiratory support were randomly assigned to HFNC and CPAP groups with 1:1 treatment allocation ratio. In this analysis, 118 patients were excluded because they did not consent to accessing their medical records, did not consent to follow-up questionnaire or did not receive respiratory support. MEASUREMENTS AND MAIN RESULTS: The primary outcome of this study is the incremental net monetary benefit (INB) of HFNC compared with CPAP using a willingness-to-pay threshold of £20,000 per QALY gain. INB is calculated based on total costs and quality adjusted life years (QALYs) at 6 months. The findings suggest modest heterogeneity in cost-effectiveness of HFNC compared with CPAP at the subgroup level, while greater heterogeneity is detected at the individual level. CONCLUSIONS: The estimated overall INB of HFNC is smaller than the INB for patients with better baseline status suggesting that HFNC can be more cost-effective among less severely ill patients.

Assessment of high-flow nasal cannula efficacy in humidification of infant airways: A computational fluid dynamics approach.

INTRODUCTION: High-flow nasal cannula therapy has garnered significant interest for managing pathologies affecting infants' airways, particularly for humidifying areas inaccessible to local treatments. This therapy promotes mucosal healing during the postoperative period. However, further data are needed to optimize the use of these devices. In vivo measurement of pediatric airway humidification presents a challenge; thus, this study aimed to investigate the airflow dynamics and humidification effects of high-flow nasal cannulas on an infant's airway using computational fluid dynamics. METHODS: Two detailed models of an infant's upper airway were reconstructed from CT scans, with high-flow nasal cannula devices inserted at the nasal inlets. The airflow was analyzed, and wall humidification was modeled using a film-fluid approach. RESULTS: Air velocities and pressure were very high at the airway inlet but decreased rapidly towards the nasopharynx. Maximum relative humidity-close to 100%-was achieved in the nasopharynx. Fluid film development along the airway was heterogeneous, with condensation primarily occurring in the nasal vestibule and larynx. CONCLUSION: This study provides comprehensive models of airway humidification, which pave the way for future studies to assess the impact of surgical interventions on humidification and drug deposition directly at operative sites, such as the nasopharynx or larynx, in infants.

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.

High-flow nasal cannula use in pediatric patients for other indications than acute bronchiolitis-a scoping review of randomized controlled trials.

The objective of the study is to summarize current literature on high-flow nasal cannula (HFNC) use for different indications in pediatric patient excluding acute bronchiolitis and neonatal care. The study design is a systematic scoping review. Pubmed, Scopus, and Web of Science databases were searched in February, 2023. All abstracts and full texts were screened by two independent reviewers. Randomized controlled trials focusing on HFNC use in pediatric patients (age < 18 years) were included. Studies focusing on acute bronchiolitis and neonatal respiratory conditions were excluded. Study quality was assessed by Cochrane risk of bias 2.0 tool. The main outcomes are patient groups and indications, key outcomes, and risk of bias. After screening 1276 abstracts, we included 22 full reports. Risk of bias was low in 11 and high in 5 studies. We identified three patient groups where HFNC has been studied: first, children requiring primary respiratory support for acute respiratory failure; second, perioperative use for either intraprocedural oxygenation or postoperative respiratory support; and third, post-extubation care in pediatric intensive care for other than postoperative patients. Clinical and laboratory parameters were assessed as key outcomes. None of the studies analyzed cost-effectiveness.Conclusion: This systematic scoping review provides an overview of current evidence for HFNC use in pediatric patients. Future studies should aim for better quality and include economic evaluation with cost-effectiveness analysis.Protocol registration: Protocol has been published https://osf.io/a3y46/ .

Biofilm Assessment and Metagenomic Analysis of Venoarterial Extracorporeal Membrane Oxygenation Cannulas and Membrane Oxygenators.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) exposes the patient to infectious complications related to the cannulas or the site of insertion. The aim of the current study was to investigate and compare the prevalence of cannula and membrane oxygenators colonization using three different methods: microbiological culture, scanning electron microscopy, and metagenomic (rRNA 16S analysis). A monocentric prospective study was conducted between December 2017 and June 2018. Consecutive patients undergoing VA-ECMO support for refractory cardiac arrest or cardiogenic shock were included. Ten patients were included with a median age of 64 (52-62) years. Venoarterial extracorporeal membrane oxygenation was inserted for refractory cardiac arrest in five (50%), cardiogenic shock in four (40%), and self-poisoning in one (10%) cases. Microbiological culture of all (8/8, 100%) membrane oxygenators was negative, whereas all (10/10, 100%) were colonized by biofilm, and eight (8/9, 89%) presented bacterial DNA. Three (3/9, 33%) arterial and venous cannulas were positive in culture and seven (7/9, 78%) were colonized by biofilm, respectively. Seven (7/9, 78%) arterial and four (4/9, 44%) venous cannulas presented bacterial DNA. Colonization of cannulas and membranes is more frequent when assessed by electron microscopy or metagenomic analysis than with culture. Membrane oxygenators are more often colonized than cannulas.

Financial outcomes of high-flow nasal cannula use for bronchiolitis on the general pediatric floor.

High-flow nasal cannula (HFNC) is an increasingly common treatment utilized for bronchiolitis on general pediatric hospital floors. This could present a financial burden for hospitals if reimbursement has not accounted for the increased costs associated with increased HFNC use. Pediatric Health Information System and Revenue Management Program data set discharges from 2018 to 2019 were utilized to calculate the ratio of reimbursements to costs as a cost coverage ratio (CCR). The CCR was compared by HFNC use, the severity of illness, and payor type. The CCR was highest at 1.68 for children with high severity and HFNC use but varied greatly by payor. The lowest CCR at 0.77 was seen for children with low severity and public insurance and indicated potential financial losses for these patients. This was lower than low-severity patients on HFNC with private payors (1.68) and high-severity patients on HFNC with public payors (1.18).

Systematic review and cost-utility of high flow nasal cannula versus continuous positive airway pressure in children with acute severe or moderate bronchiolitis in Colombia.

BACKGROUND: Nasal Continuous Positive Airway Pressure (CPAP) and High-Flow Nasal Cannula (HFNC) have emerged as alternatives to orotracheal intubation and conventional invasive ventilation in patients with moderate to severe bronchiolitis. This study aims to evaluate the evidence and the cost-utility of HFNC compared to CPAP in infants with moderate-severe bronchiolitis in Colombia. METHODS: The search includes electronic databases such as Pubmed, ScienceDirect, and Embase. Through inclusion and exclusion criteria, screen randomized controlled trials. A decision tree model was used to estimate the cost-utility of CPAP compared with HFNC in infants with moderate-severe bronchiolitis. Sensitivity analysis of transition probabilities, utilities, and cost was carried out. RESULTS: Incorporate five studies that meet the criteria. The risk of intubation rate in the patients with CPAP is lower than HFNC (relative risk 0.62; 95% confidence interval 0.46-0.84; I2 = 0%) The base-case analysis showed that compared with HFNC, CPAP was associated with lower costs and higher quality-adjusted life years (QALYs). The expected annual cost per patient with CPAP was US$17,574 and with HFNC was US$29,421. The QALYs per person estimated with CPAP were 0.92 and with HFNC was 0.91. This position of absolute dominance of CPAP (CPAP has lower costs and higher QALYs than HFNI) makes it unnecessary to estimate the incremental cost-utility ratio. CONCLUSIONS: CPAP is cost-effective, over the HFNC, in infants with severe-moderate bronchiolitis in Colombia. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines and should be replicated to validate their results in other countries.

Prevalence of high flow nasal cannula therapy use for management of infants with bronchiolitis in Australia and New Zealand.

AIM: To determine the prevalence of high flow nasal cannula (HFNC) therapy in infants presenting to hospital in Australia and New Zealand with bronchiolitis over four bronchiolitis seasons. Secondary aims were to determine temporal trends in HFNC use, and associations between HFNC, hospital length of stay (LOS) and intensive care unit (ICU) admission. METHODS: A planned sub-study of a multi-centre international cluster randomised controlled trial investigating knowledge translation strategies for a bi-national bronchiolitis guideline. Demographics, management and outcomes data were collected retrospectively for infants presenting with bronchiolitis to 26 hospitals between 1 May 2014 and 30 November 2017. Prevalence data are presented as absolute frequencies (95% confidence interval (CI)) with differences between groups for continuous and categorical variables analysed using linear and logistic regression, respectively. RESULTS: 11 715 infants were included with 3392 (29.0%, 95% CI (28.1-29.8%)) receiving oxygen therapy; of whom 1817 (53.6%, 95% CI (51.9-55.3%)) received HFNC. Use of oxygen therapy did not change over the four bronchiolitis seasons (P = 0.12), while the proportion receiving HFNC increased (2014, 336/2587 (43.2%); 2017, 609/3720 (57.8%); P ≤ 0.001). Infants who received HFNC therapy were not substantially different to infants who received oxygen therapy without HFNC. HFNC use was associated with increases in both hospital LOS (P < 0.001) and ICU admissions (P < 0.001). CONCLUSION: Use of HFNC therapy for infants with bronchiolitis increased over 4 years. Of those who received oxygen therapy, the majority received HFNC therapy without improvement in hospital LOS or ICU admissions. Strategies to guide appropriate HFNC use in infants with bronchiolitis are required.

From little things, big things grow: An exploratory analysis of the national cost of peripheral intravenous catheter insertion in Australian adult emergency care.

OBJECTIVE: To estimate the total economic impact of peripheral intravenous catheter (PIVC) or cannula insertion and use in adult Australian EDs, including those cannulas that remain unused for therapeutic purposes. METHODS: Searches on Australian government websites were conducted to find rates of insertion, complications and cost of cannula; following this, gaps in national data sets were filled with MEDLINE and PubMed searches to estimate the total cost of cannula use in Australian EDs. Once the data were collected, totals were combined to establish an estimated cost for the listed categories. RESULTS: The estimated cost of cannulation in Australia may be up to A$594 million per year, including the cost of insertion (equipment and staff), cost of complications such as Staphylococcus aureus bacteraemia and phlebitis, and patient-centred costs (lost patient productivity, infiltration, occlusion and dislodgement). Approximately A$305.9 million is attributed to unused cannulas and approximately 11 790 days of clinician time is spent annually inserting cannula that remains idle. CONCLUSION: The figures developed in the present study represent an important educational opportunity to encourage thoughtful consideration of all interventions, no matter how small. ED cannula insertion represents a large economic and health cost to Australia's health system, many of which remain unused. There are no national data sets that record complications associated with PIVCs and we highlight the urgent need for improved data.

Antecubital Vein Cannula Position Impacts Assessment of Forearm Glucose Uptake During an Oral Glucose Challenge in Healthy Volunteers.

INTRODUCTION: Skeletal muscle is a major site for whole-body glucose disposal, and determination of skeletal muscle glucose uptake is an important metabolic measurement, particularly in research focussed on interventions that impact muscle insulin sensitivity. Calculating arterial-venous difference in blood glucose can be used as an indirect measure for assessing glucose uptake. However, the possibility of multiple tissues contributing to the composition of venous blood, and the differential in glucose uptake kinetics between tissue types, suggests that sampling from different vein sites could influence the estimation of glucose uptake. This study aimed to determine the impact of venous cannula position on calculated forearm glucose uptake following an oral glucose challenge in resting and post-exercise states. MATERIALS AND METHODS: In 9 young, lean, males, the impact of sampling blood from two antecubital vein positions; the perforating vein ('perforating' visit) and, at the bifurcation of superficial and perforating veins ('bifurcation' visit), was assessed. Brachial artery blood flow and arterialised-venous and venous blood glucose concentrations were measured in 3 physiological states; resting-fasted, resting-fed, and fed following intermittent forearm muscle contraction (fed-exercise). RESULTS: Following glucose ingestion, forearm glucose uptake area under the curve was greater for the 'perforating' than for the 'bifurcation' visit in the resting-fed (5.92±1.56 vs. 3.69±1.35 mmol/60 min, P<0.01) and fed-exercise (17.38±7.73 vs. 11.40±7.31 mmol/75 min, P<0.05) states. DISCUSSION: Antecubital vein cannula position impacts calculated postprandial forearm glucose uptake. These findings have implications for longitudinal intervention studies where serial determination of forearm glucose uptake is required.

The comfort assessment in healthy adults during constant-flow mode in noninvasive ventilator.

BACKGROUND: From the point of view of machine construction and hydrodynamics, this paper innovatively proposes that the essence of high-flow nasal cannula (HFNC) is a constant-flow mode in noninvasive ventilator (NIVCFM). This study enrolled healthy adults as study subjects to assess the subjective comfort assessed by visual analog scoring scale of NIVCFM/HFNC and objective comfort measured by the noise level generated by NIVCFM/HFNC, aiming to provide a scientific basis for the rational clinical application of NIVCFM/HFNC. METHODS: Forty-four healthy adults participated in this study. The noise generated by NIVCFM/HFNC is measured, and the comfort is evaluated during NIVCFM delivery at flow rates of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 L/min. RESULTS: When the ventilator flow rate is 60 L/min, the maximum noise is 65.9 dB, increasing noise by 23.7 dB from a baseline of 42.2 dB at the flow rate of 0 L/min. There was a strong nonlinear positive correlation between the noise level and the flow rates. The median score for dry mouth, nose or throat, dysphagia, sore throat, and other discomfort was 0. The median score for dyspnea was 0 at 0-30 L/min, 1 at 35-55 L/min, and 2 at 60 L/min. CONCLUSIONS: The grater the flow rate, the greater the noise generated by NIVCFM/HFNC (<65.9 dB). The maximum flow rate that most healthy adults can able to tolerate is 30 L/min, and the main discomfort is dyspnea.

Impact of a Care Bundle on Cost Saving for Noninvasive Respiratory Support for Neonates.

BACKGROUND: Neonates often receive noninvasive respiratory support via continuous positive airway pressure (CPAP) or high-flow nasal cannula oxygen (HHFNC). The decision to change from one mode to the other, however, is not evidence based, hence not standardized and does not consider cost implications. PURPOSE: To assess the introduction of a care bundle for the medical and nursing staff in a tertiary medical and surgical neonatal center with regard to any financial savings or adverse outcomes. METHODS: An education package and written guidelines were used to increase the awareness of the durations for which CPAP and HHFNC Vapotherm (VT) circuits could be used and the costs of the circuits. RESULTS: This resulted in a cost saving of £17,000 ($22,254) for the year without adverse outcomes. IMPLICATIONS FOR PRACTICE: Introduction of a care bundle involving an education package and written guidelines to increase the awareness of the durations that circuits could be used and the costs of CPAP and HHFNC circuits among the medical and nursing staff can lead to cost savings when incorporated into clinical practice. IMPLICATIONS FOR RESEARCH: Strategies, particularly during weaning, which involve changing from one form of noninvasive respiratory support to another, need a greater evidence base. Future research should include awareness of the duration different circuits could be used and the cost implications of changes between modes and hence circuits.

Oxygen Economics: The Use of Heated High-Flow Nasal Oxygen in Air Medical Transport of the Adult Patient.

The use of oxygen via a heated high-flow nasal cannula (HHFNC) in transport of the adult patient experiencing hypoxemic respiratory failure is an emerging and successful adjunct. Although early intubation was thought to be the safest intervention early in the coronavirus disease 2019 pandemic, what we have learned over the past year was that it would serve the patient best to avoid intubation. We discuss an individual case study of a coronavirus disease 2019-infected patient who required subsequent interfacility air transport to our quaternary care facility. This patient presented to the receiving air medical team on HHFNC. Before January 2021, the capability of this program to transport these patients on HHFNC was not possible because our current ventilation platforms had to be upgraded to include the high-flow option and because of the relative infancy of the HHFNC platforms available for adult air transport. The previously noted approach to not intubate these patients, or to certainly use caution when making the decision to intubate, was not the common theme until late in 2020. Presented in this case discussion will be pertinent positive and negatives as they relate to transporting the patient on HHFNC to include the all-important issue of oxygen supply and demand. The authors would emphasize that the named products in this case are simply products used by the receiving air medical program and do not in any way support an endorsement of these products over any other platforms used to provide positive patient interventions and outcomes.

Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis.

INTRODUCTION: In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. METHODS: We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. RESULTS: No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ2 = 1.007, p > 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ2 = 2.082, p > 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate <5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ2 = 0.838, p > 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ2 = 18.428, p < 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ2 = 26.194, p < 0.001). DISCUSSION/CONCLUSION: Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

Budget impact analysis of high-flow nasal cannula for infant bronchiolitis: the Colombian National Health System perspective.

BACKGROUND: High-flow nasal cannula is a non-invasive ventilation system that was introduced as an alternative to continuous positive airway pressure), with a marked increase in its use in pediatric care settings. However, the expected budget impact of this intervention has not been explicitly estimated. This study aimed to evaluate the budget impact of the high-flow nasal cannula for acute bronchiolitis in Colombia. METHODS: A budget impact analysis was performed to evaluate the potential financial impact deriving from high-flow nasal cannula during 2020. The analysis considered a 5-year time horizon and Colombian National Health System perspective. The incremental budget impact was calculated by subtracting the cost of the new treatment, in which a high-flow nasal cannula is reimbursed, from the cost of the conventional treatment without a high-flow nasal cannula (supplemental oxygen through a nasal cannula up to a maximum of 2 liters per minute). Univariate one-way sensitivity analyses were performed. RESULTS: In the base-case analysis the 5-year costs associated with high-flow nasal cannula and no- high-flow nasal cannula were estimated to be US$159,585,618 and US$172,751,689 respectively, indicating savings for Colombian National Health equal to US$13,166,071 if the high-flow nasal cannula is adopted for the routine management of patients with acute bronchiolitis. This result was robust in univariate sensitivity one-way analysis. CONCLUSION: High-flow nasal cannula was cost-saving in emergency settings for treating infants with acute bronchiolitis. This evidence can be used by decision-makers in our country to improve clinical practice guidelines and should be replicated to validate their results in other middle-income countries.

Soporte respiratorio no invasivo mecánico en pacientes COVID-19 / Non-invasive mechanical respiratory support in COVID-19 patients

CONTEXTO CLÍNICO: La enfermedad por el Coronavirus 2019 (COVID­19, por su sigla en inglés Coronavirus Disease 2019) es una enfermedad respiratoria de humanos producida por un nuevo coronavirus identificado con la sigla SARS-CoV-2. El 11 de marzo de 2020 la Organización Mundial de la Salud (OMS) declaró la infección por COVID-19 como una pandemia. Desde ese momento hasta el 14 de Enero 2021, la circulación del virus SARS-CoV-2 se ha reportado en más de 200 países reportándose más de 100.000.000 casos activos a la fecha y más de 72.543.860 casos cerrados de los cuales el 3% de estos han muerto (2151000 casos). El período de incubación de la infección es de 2 a 14 días. La mayor parte de los contagios se producen de persona a persona, siendo altamente transmisible. La clínica varía desde casos asintomáticos a cuadros febriles con tos y dificultad respiratoria, neumonía y distrés respiratorio. También puede acompañarse de alteraciones gastrointestinales. TECNOLOGÍA: La terapia de alto flujo mediante cánulas nasales consiste en la utilización de una mezcla de gas a flujos altos (hasta 60 litros por minuto) con proporciones variables de aire y oxígeno (fracción inspirada de oxígeno-FiO2-) administrados a través de una cánula nasal. Este gas administrado debe estar caliente y humidificado al 100%. Las ventajas con respecto al oxígeno convencional son un aporte constante de FiO2, reducción del espacio muerto y generación de una presión positiva que conllevan a una redistribución de líquido intraalveolar y a reclutamiento alveolar. Aunque en el momento actual existe incertidumbre en relación con la dispersión de partículas en este modo terapéutico, suele sugerirse la colocación de un barbijo quirúrgico por encima de las cánulas nasales en pacientes con infección por SARS-CoV-2. OBJETIVO: El objetivo del presente informe es evaluar la evidencia disponible acerca de la eficacia, seguridad y aspectos relacionados a las políticas de cobertura del uso del uso de terapia de alto flujo con cánula nasal y de ventilación mecánica no invasiva para pacientes con insuficiencia respiratoria aguda moderada a severa en infección con SARS-CoV-2. MÉTODOS: Se realizó una búsqueda en las principales bases de datos bibliográficas, en buscadores genéricos de internet, y financiadores de salud. Se priorizó la inclusión de revisiones sistemáticas (RS), ensayos clínicos controlados aleatorizados (ECAs), evaluaciones de tecnologías sanitarias (ETS), evaluaciones económicas, guías de práctica clínica (GPC) y políticas de cobertura de diferentes sistemas de salud. RESULTADOS: Se incluyeron una revisión sistemática, una revisión narrativa y tres series de casos para la terapia de alto flujo con cánula nasal y tres series de casos para ventilación mecánica no invasiva, 14 GPC para Soporte respiratorio no invasivo en COVID-19. CONCLUSIONES: Evidencia de baja calidad proveniente de series de casos de pacientes con infección respiratoria por SARS-CoV-2 moderada a severa tratados con terapia de alto flujo con cánula nasal con PaO2 / FIO2<200 muestran que su uso podria estar asociado a menores tasas de intubación. Su desvenjata es la generacion de aerosoles. Evidencia de baja calidad del uso de ventilación mecánica no invasiva y ventilación con presión soporte vs ventilacion invasiva no ha mostrado ser superior en pacientes con COVID 19 moderados y severos, las tasas de mortalidad de este grupo se asocia a la edad y comorbilidades de los pacientes. Por lo que no puede establecer su eficacia en la reducción de la mortalidad o en la mejoría clínica. El Ministerio de Salud de la Nación y la Sociedad Argentina de Terapia Intensiva no recomiendan el uso de terapia de alto flujo con cánula nasal ni la ventilación mecánica no invasiva. En caso de instaurarse, sugieren utilizar equipo de protección personal máximo, usar casco o helmet si está disponible para la ventilación mecánica no invasiva, respirador de dos ramas e idealmente habitación con presión negativa; así como, no demorar la ventilación mecánica invasiva si no hay rápida respuesta. Recientemente La Asociacion de Medicina Respiratoria de Argentina, dado el estado de situacion epidemiologia frente a la pandemia por COVID-19, recomiendan el uso todas las medidas de soporte ventilatorio disponibles en la actualidad (invasivo y no invasivo), con el objetivo que en la medida de lo posible , ningún paciente quede sin asistencia, enfatizando en las medidas de protección personal según el nivel de atencion y la medida de soporte ventilatoria implementada. La mayoría de guías europeas, americanas, latinoamericanas en sus recomendaciones y consensos internacionales sugieren el uso de terapia de alto flujo con cánula nasal como primera linea y solo el uso de ventilación mecánica no invasiva en pacientes con insuficiencia respiratoria hipoxémica a pesar de la oxigenoterapia con canulas o re agudización de una insuficiencia respiratoria hipercápnica en pacientes con enfermedad pulmonar obstructiva crónica. De utilizarse estas terapias de sostén respiratorio, recomiendan aislamiento del paciente, preferentemente en sala con presión negativa, utilización de equipo completo de protección personal por parte del personal de salud, que el paciente utilice barbijo en caso de terapia con cánulas de alto flujo, y casco o helmet en los casos en los que se utiliza ventilación mecánica no invasiva.

Assessment of dispersion of airborne particles of oral/nasal fluid by high flow nasal cannula therapy.

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.