Washout Of Dead Space Research Articles

Role of high flow nasal therapy in Intensive Care Units

Introduction and purpose: High Flow Nasal Therapy is quite new respiratory support method, although recently it became more popular – especially during COVID-19 pandemic. Physiological mechanisms as well as main applications were observed and described in several randomized controlled trias and metaanalisys. The purpose of this review is to present fundamental studies and indicate applications of this method.
 Brief description of the state of knowladge: Breathing mixture with a maximum flow 60l/min needs to be heated and humidified to protect the airways from dryness. Optimal humidity improves mucocilary clearance, reduces inflammation of the airways and energy expenditure, especially in acute respiratory failure. High flow nasal therapy may imrpove the mechanics of breathing also by washout of nasopharyngeal dead space and generating positive airway pressure during exhalation, which keeps airways open and prevents the alveoli from collapsing. High flow therapy can be use in many different applications but at Intensive Care Unit the most important are: acute hypoxemia, during extubation or rest breaks from NIV. It is important to monitor the patient and predict the need for intubation on time. There are physiological states that we shoud focus on: respiratory rate, dyspnea or work of breathing, but it is good to know ROX index which can be helpful to assess the success of the therapy.
 Summary (conlcusions): High flow nasal therapy is a simple and safety respiratory support method that can be applicable at Intensive Care Units. It can lower the intubation numbers and help during NIV rest breaks. High flow nasal therapy is a very promising method for all patients with respiratory failure but it is important to monitor the patient and not delay the intubation.

Instrumental dead space: A glass ceiling for extremely low birth weight preterm infants? A dead space washout bench study.

When ventilating extremely low birth weight infants, clinicians face the problem of instrumental dead space, which is often larger than tidal volume. Hence, aggressive ventilation is necessary to achieve CO2 removal. Continuous tracheal gas insufflation can wash out CO2 from dead space and might also have an impact on O2 and water vapor transport. The objective of this bench study is to test the impact of instrumental dead space on the transport of CO2 , O2 , and water vapor and the ability of continuous tracheal gas insufflation to remedy this problem during small tidal volume ventilation. A test-lung located in an incubator at 37°C was ventilated with pressure levels needed to reach different tidal volumes from 1.5to 5 mL. End-tidal CO2 at the test-lung exit, O2 concentration, and relative humidity in the test-lung were measured for each tidal volume with and without a 0.2 L/min continuous tracheal gas insufflation flow. CO2 clearance was improved by continuous tracheal gas insufflation allowing a 28%-44% of tidal volume reduction. With continuous tracheal gas insufflation, time to reach desired O2 concentration was reduced from 20% to 80% and relative humidity was restored. These results are inversely related to tidal volume and are particularly critical below 3 mL. For the smallest tidal volumes, reduction of instrumental dead space seems mandatory for CO2 , O2 , and water vapor transfer. Continuous tracheal gas insufflation improved CO2 clearance, time to reach desired O2 concentration and humidification of airways and, thus, may be an option to protect lung development.

Efficacy of Nasal High-Flow Oxygen Therapy in Chronic Obstructive Pulmonary Disease Patients in Long-Term Oxygen and Nocturnal Non-Invasive Ventilation during Exercise Training.

High-flow oxygen therapy (HFOT) improves gas exchange and dead space washout and reduces the level of work required for breathing. This study aimed to evaluate pulmonary rehabilitation (PR) combined with HFOT in COPD patients treated with nocturnal non-invasive ventilation (NIV) and long-term oxygen therapy (LTOT). In particular, we sought to discover whether the addition of HFOT during exercise training could improve patients’ performance, mainly with regard to their Six-Minute Walking Test (6MWT) outcomes, and reduce the exacerbation rates, periods of rehospitalization or need to resort to unscheduled visits. Thirty-one COPD subjects (13 female) who used nocturnal NIV were included in a randomized controlled trial and allocated to one of two groups: the experimental group (EG), with 15 subjects, subjected to PR with HFOT; and the control group (CG), with 16 subjects, subjected to PR without HFOT. The primary outcome of the study was the observation of changes in the 6MWT. The secondary outcome of the study was related to the rate of exacerbation and hospitalization. Data were collected at baseline and after one, two and three cycles of cycle-ergometer exercise training performed in 20 supervised sessions of 40 min thrice per week, with a washout period of 3 months between each rehabilitation cycle. Statistical significance was not found for the 6MWT distance (W = 0.974; p = 0.672) at the last follow-up, but statistical significance was found for the Borg scale in regard to dyspnea (W = 2.50; p < 0.001) and fatigue (W = 2.00; p < 0.001). HFOT may offer a positive option for dyspnea-affected COPD patients in the context of LTOT and nocturnal NIV.

Dead space washout by intentional leakage flow during conventional ventilation of premature infants-an experimental study.

ObjectiveInvasive mechanical ventilation poses a strong risk factor for the development of chronic lung disease in preterm infants. A reduction of the dead space as part of the total breathing volume would reduce the ventilation effort and thereby lower the risk of ventilator‐induced lung injuries. In this experimental study, we compared the efficacy of mechanical dead space washout via uncontrolled and controlled leakage flow in their ability to eliminate CO2 during conventional ventilation in preterm infants.MethodsThree frequently used neonatal ventilators, operating under standard conventional ventilating parameters, were individually connected to a test lung. To maintain a constant physiological end‐expiratory pCO2 level during ventilation, the test lung was continuously flooded with CO2. A side port in the area of the connector between the endotracheal tube and the flow sensor allowed breathing gas to escape passively or in a second experimental setup, regulated by a pump. Measurements of end‐expiratory pCO2 were taken in both experiments and compared to end‐expiratory pCO2 levels of ventilation without active dead space leakage.ResultsFollowing dead space washout, a significant reduction of end‐expiratory pCO2 was attained. Under conditions of uncontrolled leakage, the mean decrease was 14.1% while controlled leakage saw a mean reduction of 16.1%.ConclusionWashout of dead space by way of leakage flow is an effective method to reduce end‐expiratory pCO2. Both controlled and uncontrolled leakage provide comparable results, but precise regulation of leakage allows for a more stable ventilation by preventing uncontrolled loss of tidal volume during inspiration.

Upper airway pressure distribution during nasal high-flow therapy

Two working mechanisms of Nasal High-Flow Therapy (NHFT) are washout of anatomical dead space and provision of positive end-expiratory pressure (PEEP). The extent of both mechanisms depends on the respiration aerodynamics and the corresponding pressure distribution: at end-expiration the onset of uniform pressure indicates the jet penetration length, and the level of the uniform pressure is the PEEP. The clinical problem is that adequate measurements in patients are presently impossible. In this study, the respiratory pressure distribution is therefore measured in 3D-printed anatomically correct upper-airway models of an adult and an infant. Assuming that elastic fluctuations in airway anatomy are sufficiently small, the aerodynamics in these rigid models will be very similar to the aerodynamics in patients. It appears that, at end-expiration, the jet penetrates into or slightly beyond the nasal cavity, hardly depending on cannula size or NHFT flow rate. PEEP is approximately proportional to the square of the flow rate: it can be doubled by increasing the flow rate by 40%. In the adult model, PEEP is accurately predicted by the dynamic pressure at the prong-exits, but in the infant model this method fails. During respiration, large pressure fluctuations occur when the cannula is relatively large compared to the nostrils.

High-Flow Nasal Cannula Reduces Effort of Breathing But Not Consistently via Positive End-Expiratory Pressure

High-flow nasal cannula (HFNC) therapy reduces the effort of breathing in patients with bronchiolitis, but the mechanisms are not understood. Theorized mechanisms include dead space washout and positive end-expiratory pressure (PEEP) application. What are the mechanisms of action of HFNC therapy in patients with bronchiolitis? Prospective, single-center study of children 3 years of age or younger with bronchiolitis from January 2020 through March 2021. Flow was titrated between 0.5 and 2 L/kg/min. Electrical impedance tomography measured end-expiratory lung impedance (EELZ) change as an end-expiratory lung volume (EELV) change surrogate and change in tidal impedance difference (ΔZ) as a tidal volume (VT) surrogate. A subset showed manometry measuring esophageal pressure change (ΔPes; transpulmonary pressure surrogate) and pressure rate product (PRP; effort of breathing metric). We hypothesized that EELV and VT would not change and that effort would reduce via respiratory rate (not ΔPes). Measurements were reported as the difference from 0.5 L/kg/min. We studied 22 patients in total, 10 with esophageal manometry. Median EELZ increased by 0.36 arbitrary unit (AU), 2.42 AU, and 4.8 AU at 1 L/kg/min, 1.5 L/kg/min, and 2 L/kg/min (P= .01, 2 L/kg/min vs0.5 L/kg/min), which corresponded to a median increase in EELV of 1.8mL/kg between 0.5 and 2 L/kg/min. Seven patients showed an increase in EELZ of > 5 AU, 12 showed no change in EELZ (± 5 AU), and three showed a decrease in EELZ of > 5 AU. ΔZ (ie, VT) did not change from 0.5 L/kg/min to 2 L/kg/min (median change, 0.29 AU; P= .48). Median PRP decreased by 78cm H2O/min from 0.5 L/kg/min to 2 L/kg/min (P= .02), with all patients demonstrating a reduction in PRP, with a nonsignificant change in ΔPes (P= .68). Increasing HFNC in children with bronchiolitis reduces the effort of breathing, but no consistent increase occurs in end-expiratory lung volume and no significant change occurs in VT or transpulmonary pressure. This suggests that PEEP application is not the primary mechanism of action of HFNC in children with bronchiolitis.

High-flow nasal cannula for respiratory failure in adult patients.

The high-flow nasal cannula (HFNC) has been recently used in several clinical settings for oxygenation in adults. In particular, the advantages of HFNC compared with low-flow oxygen systems or non-invasive ventilation include enhanced comfort, increased humidification of secretions to facilitate expectoration, washout of nasopharyngeal dead space to improve the efficiency of ventilation, provision of a small positive end-inspiratory pressure effect, and fixed and rapid delivery of an accurate fraction of inspired oxygen (FiO2) by minimizing the entrainment of room air. HFNC has been successfully used in critically ill patients with several conditions, such as hypoxemic respiratory failure, hypercapneic respiratory failure (exacerbation of chronic obstructive lung disease), post-extubation respiratory failure, pre-intubation oxygenation, and others. However, the indications are not absolute, and much of the proven benefit remains subjective and physiologic. This review discusses the practical application and clinical uses of HFNC in adults, including its unique respiratory physiologic effects, device settings, and clinical indications.

High-Flow Nasal Oxygen Therapy in Acute Hypoxemic Respiratory Failure: Concise Review on Technology and Initial Methodology.

High-flow nasal cannula oxygen therapy (HFNCOT) system consists of an air/oxygen supply system capable of delivering up to 100% humidified and heated oxygen at a flow rate of up to 80 L/min. The system includes a blender, active humidifier, single heated tube, and nasal cannula. HFNCOT has many physiological advantages compared with other standard oxygen therapies, such as anatomical dead space washout, more constant fraction of inspired oxygen, positive end-expiratory (PEEP) effect, supplement of adequate humidification and maintenance of muco-ciliary function. HFNCOT is mostly used for hypoxemic acute respiratory failure, although it also has other indications. HFNCOT is a common choice of physicians as its technology makes it more silent and comfortable. Though HFNCOT is used in many clinical settings, there is a lack of publications addressing devices and initial settings. We present a review on HFNCOT, with focus on device and application methodology.

Nasal high flow oxygen therapy during acute admissions or periods of worsening symptoms.

Nasal high flow therapy (NHF) is increasingly used in acute care settings. In this review, we consider recent advances in the utilization of NHF in chronic obstructive pulmonary disease (COPD), terminal cancer and symptom management. Considerations around NHF use during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are also discussed. NHF enables humidification and high flows to be provided together with titrated, supplemental oxygen therapy. Compared to conventional oxygen therapy, NHF improves respiratory physiology by reducing workload, enhancing muco-ciliary clearance and improving dead space washout. Some studies suggest that early use of NHF in people being cared for in the emergency department leads to lower rates of invasive ventilation and noninvasive ventilation. There is also emerging evidence for NHF use in people with COPD and chronic respiratory failure, and in palliative care. NHF is comfortable, well-tolerated and safe for use in the management of breathlessness in people with cancer. NHF can be delivered by face mask to patients with SARS-CoV-2 infection, to ease the burden on critical care resources. The evidence base for NHF is rapidly growing and offers promise in relieving troublesome symptoms and for people receiving palliative care.

High flow versus conventional nasal cannula for oxygenation and ventilation maintenance during surgery with intravenous deep sedation by propofol: a randomized controlled study

BackgroundThe dead space washout and provision of some level of positive airway pressure by nasal high-flow (NHF) cannula could improve the efficiency of ventilation, oxygenation and maintenance of the upper airway in patients undergoing deep sedation. This study aimed to compare the incidences of events represented oxygenation and ventilation, i.e. desaturation and upper airway obstruction, and arterial blood gas (ABG) levels between using NHF cannula and conventional nasal cannula (NC2) during deep sedation of adult surgical patients.MethodsIn this prospective randomized single-blinded study, the patients who were 20–80 years old, ASA physical status of 1 to 3, scheduled for surgery under intravenous sedation (IVS) were included. The patients were randomly divided into two groups, i.e., NC2 or NHF groups. Propofol infusion was given to maintain deep sedation. The desaturation (SpO2 < 92%) and upper airway obstruction events (presence of snoring with paradoxical breathing) after application of NC2 or NHF were observed and collected. Other outcomes included interventions during IVS, such as jaw lifting or airway instrument insertion, mouth dryness, and post- ABG analyses were also collected and compared.ResultsThirty-six patients undergoing endovascular surgery were randomized into NC2 or NHF groups (18 in each group). No patients dropped out of the study. There were no significant differences in age, sex, ASA physical status, pre-sedation and pre-application of NC2 and NHF ABG analyses (PaO2, SaO2, pH, PaCO2, and PaO2/FiO2). NHF group had significantly lower in the incidence of desaturation [5 (27.78%) vs 13 (72.22%), p = 0.008], upper airway obstruction [4 (22.22%) vs 13 (72.22%), p = 0.003], and airway maneuver [6 (33.33%) vs 13 (72.22%), p = 0.019] than NC2 group. There were no differences in the ABG analyses after oxygen supplementation and no significant differences in mouth dryness between groups.ConclusionThe use of NHF cannula in patients undergoing endovascular surgery under deep sedation reduced desaturation events and required fewer airway interventions than NC2 with no difference in arterial blood gas analyses and mouth dryness.

Repackaging of Malfunctioning High-flow Nasal Cannula as a Rescue Oxygen Therapy: An Innovation amid COVID-19 Crisis.

ABSTRACTOxygen supplementation is required for approximately 14% of the patients diagnosed of having COVID-19 infection. Despite the use of conventional oxygen therapy, 5% among these require treatment in the intensive care unit (ICU). Here, we are describing a situation in which oxygen therapy was delivered to the patients by making an assembly of oxygen tubing, three-way stopcock, and high-flow nasal cannula (HFNC) present in the hospital setting following the malfunction of air blender of HFNC machine (Fig. 1). This assembly might be useful as rescue oxygen therapy during a malfunction of HFNC machine and in resource-limited settings where HFNC machine is not available. The mechanisms of action could be (1) washout of anatomic dead space due to medium oxygen flow, (2) improved gas mixing in large airways, and (3) increased oxygen concentration inside the conducting airway.How to cite this article: Kumar A, Kumar A, Kumar N, Kumar A, Singh V, Kumar S, et al. Repackaging of Malfunctioning High-flow Nasal Cannula as a Rescue Oxygen Therapy: An Innovation amid COVID-19 Crisis. Indian J Crit Care Med 2021;25(8):948–949.

Effects of nasal high flow on nocturnal hypercapnia, sleep, and sympathovagal balance in patients with neuromuscular disorders

PurposeIn neuromuscular disorders (NMD), inspiratory muscle weakness may cause sleep-related hypoventilation requiring non-invasive ventilation (NIV). Alternatively, nasal high flow therapy (NHF) may ameliorate mild nocturnal hypercapnia (NH) through washout of anatomical dead space and generation of positive airway pressure. Ventilatory support by NIV or NHF might have favourable short-term effects on sympathovagal balance (SVB). This study comparatively investigated the effects of NHF and NIV on sleep-related breathing and SVB in NMD patients with evolving NH.MethodsTranscutaneous CO2 (ptcCO2), peripheral oxygen saturation (SpO2), sleep outcomes and SVB (spectral analysis of heart rate, diastolic blood pressure variability) along with haemodynamic measures (cardiac index, total peripheral resistance index) were evaluated overnight in 17 patients. Polysomnographies (PSG) were randomly split into equal parts with no treatment, NIV and NHF at different flow rates (20 l/min vs. 50 l/min). In-depth analysis of SVB and haemodynamics was performed on 10-min segments of stable N2 sleep taken from each intervention.ResultsCompared with no treatment, NHF20 and NHF50 did not significantly change ptcCO2, SpO2 or the apnea hypopnea index (AHI). NHF50 was poorly tolerated. In contrast, NIV significantly improved both gas exchange and AHI without adversely affecting sleep. During daytime, NHF20 and NHF50 had neutral effects on ventilation and oxygenation whereas NIV improved ptcCO2 and SpO2. Effects of NIV and NHF on SVB and haemodynamics were neutral during both night and daytime.ConclusionsNHF does not correct sleep-disordered breathing in NMD patients with NH. Both NHF and NIV exert no immediate effects on SVB.

High-flow therapy: physiological effects and clinical applications.

Humidified high-flow therapy (HFT) is a noninvasive respiratory therapy, typically delivered through a nasal cannula interface, which delivers a stable fraction of inspired oxygen (FIO2) at flow rates of up to 60 L·min−1. It is well-tolerated, simple to set up and ideally applied at 37°C to permit optimal humidification of inspired gas. Flow rate and FIO2 should be selected based on patients' inspiratory effort and severity of hypoxaemia. HFT yields beneficial physiological effects, including improved mucociliary clearance, enhanced dead space washout and optimisation of pulmonary mechanics. Robust evidence supports its application in the critical care setting (treatment of acute hypoxaemic respiratory failure and prevention of post-extubation respiratory failure) and emerging data supports HFT use during bronchoscopy, intubation and breaks from noninvasive ventilation or continuous positive airway pressure. There are limited data on HFT use in patients with hypercapnic respiratory failure, as an adjunct to pulmonary rehabilitation and in the palliative care setting, and further research is needed to validate the findings of small studies. The COVID-19 pandemic raises questions regarding HFT efficacy in COVID-19-related hypoxaemic respiratory failure and concerns regarding aerosolisation of respiratory droplets. Clinical trials are ongoing and healthcare professionals should implement strict precautions to mitigate the risk of nosocomial transmission.Educational aimsProvide a practical guide to HFT setup and delivery.Outline the physiological effects of HFT on the respiratory system.Describe clinical applications of HFT in adult respiratory and critical care medicine and evaluate the supporting evidence.Discuss application of HFT in COVID-19 and aerosolisation of respiratory droplets.

The efficacy of the WhisperFlow CPAP system versus high flow nasal cannula in patients at risk for postextubation failure: A Randomized controlled trial.

Compare the efficacy(reintubation rate) between a high-flow nasal cannula(HFNC) and the WhisperFlow CPAP system in patients at risk for postextubation failure. RCT was conducted in patients who had at least one high-risk criterion for postextubation failure. All patients were randomly assigned to CPAP or HFNC for 48h. Of 140 patients, sixty-nine were assigned to the CPAP group and 71 to the HFNC group. The reintubation rate was similar between the HFNC and WhisperFlowCPAP [5 cases(7.0%) vs. 6 cases(8.7%); P=0.76]. The postextubation respiratory failure rate was not significantly different between the HFNC and WhisperFlow CPAP groups [10 cases(14.1%)vs.7cases(10.1%); P=0.48]. The respiratory rate was lower in the HFNC than CPAP group(P=0.04). The pain rating scale score was lower in the HFNC group than in the WhisperFlow CPAP group at 24h (2.8±2.0 vs. 3.7±1.9, P=0.02) and 48h (2.8±1.8 vs. 3.8±1.9, P=0.002). We are unable to demonstrate a reduction in postextubation respiratory failure in at risk patients with the use of HFNC compared with the WhisperFlow CPAP system probably because small sample size, but HFNC was better tolerated.

Effects of nasal high flow on sympathovagal balance, sleep, and sleep-related breathing in patients with precapillary pulmonary hypertension

BackgroundIn precapillary pulmonary hypertension (PH), nasal high flow therapy (NHF) may favorably alter sympathovagal balance (SVB) and sleep-related breathing through washout of anatomical dead space and alleviation of obstructive sleep apnea (OSA) due to generation of positive airway pressure.ObjectivesTo investigate the effects of NHF on SVB, sleep, and OSA in patients with PH, and compare them with those of positive airway pressure therapy (PAP).MethodsTwelve patients with PH (Nice class I or IV) and confirmed OSA underwent full polysomnography, and noninvasive monitoring of SVB parameters (spectral analysis of heart rate, diastolic blood pressure variability). Study nights were randomly split into four 2-h segments with no treatment, PAP, NHF 20 L/min, or NHF 50 L/min. In-depth SVB analysis was conducted on 10-min epochs during daytime and stable N2 sleep at nighttime.ResultsAt daytime and compared with no treatment, NHF20 and NHF50 were associated with a flow-dependent increase in peripheral oxygen saturation but a shift in SVB towards increased sympathetic drive. At nighttime, NHF20 was associated with increased parasympathetic drive and improvements in sleep efficiency, but did not alter OSA severity. NHF50 was poorly tolerated. PAP therapy improved OSA but had heterogenous effects on SVB and neutral effects on sleep outcomes. Hemodynamic effects were neutral for all interventions.ConclusionsIn sleeping PH patients with OSA NHF20 but not NHF50 leads to decreased sympathetic drive likely due to washout of anatomical dead space. NHF was not effective in lowering the apnea-hypopnoea index and NHF50 was poorly tolerated.

High-flow nasal cannula oxygen therapy in children: a clinical review.

High-flow nasal cannula (HFNC) is a relatively safe and effective noninvasive ventilation method that was recently accepted as a treatment option for acute respiratory support before endotracheal intubation or invasive ventilation. The action mechanism of HFNC includes a decrease in nasopharyngeal resistance, washout of dead space, reduction in inflow of ambient air, and an increase in airway pressure. In preterm infants, HFNC can be used to prevent reintubation and initial noninvasive respiratory support after birth. In children, flow level adjustments are crucial considering their maximal efficacy and complications. Randomized controlled studies suggest that HFNC can be used in cases of moderate to severe bronchiolitis upon initial low-flow oxygen failure. HFNC can also reduce intubation and mechanical ventilation in children with respiratory failure. Several observational studies have shown that HFNC can be beneficial in acute asthma and other respiratory distress. Multicenter randomized studies are warranted to determine the feasibility and adherence of HFNC and continuous positive airway pressure in pediatric intensive care units. The development of clinical guidelines for HFNC, including flow settings, indications, and contraindications, device management, efficacy identification, and safety issues are needed, particularly in children.

Physiological effects of high-flow nasal cannula therapy in preterm infants

ObjectiveHigh-flow nasal cannula (HFNC) therapy is increasingly used in preterm infants despite a paucity of physiological studies. We aimed to investigate the effects of HFNC on respiratory physiology.Study designA prospective...

Nasal high flow: physiology, efficacy and safety in the acute care setting, a narrative review.

Nasal high flow (NHF) is a promising novel oxygen delivery device, whose mechanisms of action offer some beneficial effects over conventional oxygen systems. It is considered to have a number of physiological effects: it improves oxygenation, dynamic lung compliance, homogeneity and end expiratory lung volume; it decreases anatomical dead space and generates a positive airway pressure that can reduce respiratory rate, the work of breathing, and enhance patient comfort. NHF has been used as a prophylactic tool or as a treatment device mostly in patients with acute hypoxemic respiratory failure such as pre-oxygenation before intubation, immunocompromised patients and acute heart failure. Moreover, there is some evidence that NHF could be used during procedural sedation. Finally, NHF was deemed to be effective in chronic obstructive pulmonary disease patients with its positive end expiratory pressure effects and dead-space washout. However, careful monitoring is crucial to maximize NHF settings aimed at maximizing patient comfort while limiting the risk of delayed intubation. The present review presents the most updated evidence for NHF use in the adult acute care setting with the goal of providing clinicians with useful insights on the physiologic effects, main clinical indications, and safety issues of NHF treatment.

3081 Reducing Reintubation Risk in High-Risk Cardiac Surgery Patients with High Flow Nasal Cannula

OBJECTIVES/SPECIFIC AIMS: More than half a million adult patients nationally undergo cardiac surgery each year. Reintubation following cardiac surgery is common and associated with higher short- and long-term mortality, increased cost, and longer lengths of stay. The reintubation incidence is estimated at 5-10%. Patients undergoing cardiac surgery are increasing in age and comorbidity burden, and receive increasingly complex cardiac surgical procedures, complicating decision making around when to extubate postoperative patients. Compounding this complexity are financial pressures to maintain high throughput and maximize ICU bed availability. Providers are often compelled to extubate high-risk patients earlier, despite the potential for an increased risk of reintubation. Understanding the risk factors for reintubation after cardiac surgery and identifying effective interventions to reduce these reintubations is of critical importance to optimize patient outcomes. High-flow nasal cannula (HFNC) provides up to 60 liters per minute of 100% oxygen, dead space washout, and humidification to improve secretion clearance, and has shown some benefits in improving hypoxia and reducing reintubation in select populations. However, its benefit in high-risk patients undergoing cardiac surgical procedures is not known and therefore clinicians may still be reluctant to extubate these patients early and introduce HFNC, despite the known risks of prolonged intubation. To address this important issue, we aim to develop and validate a model to predict postoperative reintubation after cardiac surgery using data readily available from the electronic health record (EHR) and use this data to complete a pilot randomized controlled trial (RCT) of post-extubation HFNC to prevent reintubation in cardiac surgery patients identified as at high risk for reintubation. METHODS/STUDY POPULATION: Based on retrospective data demonstrating a 4.7% reintubation incidence within 48 hours in our CVICU, we estimate that there will be 340 reintubations available for analysis of the risk factors for reintubation to develop our predictive model from November 2, 2017 (our EHR go-live). We require 15 events per predictive variable to avoid overfitting the model, giving us at least 22 variables for analysis and inclusion in the model. Model validation and calibration will be performed using a bootstrapped validation cohort. Next, we will prospectively study 120 patients with a greater than 10% predicted risk of reintubation (double the baseline risk of the overall population) and randomly assign them to either HFNC or usual care, to test the hypothesis that HFNC decreases the rate of reintubation in high-risk patients. RESULTS/ANTICIPATED RESULTS: In addition to developing a predictive model, refining it, and validating its ability to predict the primary outcome of reintubation within 48 hours, I will further assess whether HFNC reduces total duration of mechanical ventilation, hospital length of stay, and ICU length of stay in this high-risk population. I will use these data to establish the feasibility of EHR-integrated predictive modeling and randomization, as well as to guide a future multicenter clinical trial that will pragmatically leverage the EHR for patient selection, enrollment, randomization, and data collection. DISCUSSION/SIGNIFICANCE OF IMPACT: Assuming HFNC decreases reintubation rates by 50%, at a 1:1 ratio of cases to controls, we will require 435 patients in each group (970 total), to have an 80% power and alpha of 0.05 to detect a difference. As this will require a multicenter study, we will instead focus on using data from this pilot study to: 1) refine our sample size estimates. 2) demonstrate the feasibility of our novel EHR-integrated pragmatic trial design. 3) identify and screen collaborators at other institutions, including obtaining important regulatory and legal approval. 4) establish a data safety monitoring board for the trial. 5) refine the data collection infrastructure, leveraging commercially available resources in one of the largest enterprise EHR systems (Epic) and associated resource-sharing products, such as Epic’s App Orchard.

Nasal high flow therapy for neonates: Current evidence and future directions.

Nasal high flow (nHF) therapy is a commonly used method of providing non-invasive respiratory support for neonates. It has several potential mechanisms of action: continuous distending pressure, nasopharyngeal dead space washout, provision of heated and humidified gases and reduction of work of breathing. nHF is used in a number of clinical scenarios for preterm and term infants, including primary respiratory and post-extubation support. In recent years, large trials have generated evidence pertinent to these indications. Novel applications for nHF in neonates warrant further research: during endotracheal intubation, for initial delivery room stabilisation of preterm infants and in conjunction with minimally invasive surfactant therapy.