Prediction of high-flow nasal cannula outcomes at the early phase using the modified respiratory rate oxygenation index.

BACKGROUND: This study was designed to explore the early predictive value of the respiratory rate oxygenation (ROX) index modified by PaO2 (mROX) in high-flow nasal cannula (HFNC) therapy in patients with acute hypoxemia respiratory failure (AHRF). METHOD: Seventy-five patients with AHRF treated with HFNC were retrospectively reviewed. Respiratory parameters at baseline and 2 h after HFNC initiation were analyzed. The predictive value of the ROX (ratio of pulse oximetry/FIO2 to respiratory rate) and mROX (ratio of arterial oxygen /FIO2 to respiratory rate) indices with two variations by adding heart rate to each index (ROX-HR and mROX-HR) was evaluated. RESULTS: HFNC therapy failed in 24 patients, who had significantly higher intensive care unit (ICU) mortality and longer ICU stay. Both the ROX and mROX indices at 2 h after HFNC initiation can predict the risk of intubation after HFNC. Two hours after HFNC initiation, the mROX index had a higher area under the receiver operating characteristic curve (AUROC) for predicting HFNC success than the ROX index. Besides, baseline mROX index of greater than 7.1 showed a specificity of 100% for HFNC success. CONCLUSION: The mROX index may be a suitable predictor of HFNC therapy outcomes at the early phase in patients with AHRF.

High-flow nasal cannula: Evaluation of the perceptions of various performance aspects among Chinese clinical staff and establishment of a multidimensional clinical evaluation system.

Objective: In order to facilitate education for clinical users, performance aspects of the high-flow nasal cannula (HFNC) devices were evaluated in the present study. A multidimensional HFNC clinical evaluation system was established accordingly. Materials and Methods: Clinical staff from Chinese hospitals were invited to participate in an online questionnaire survey. The questionnaire was mainly about the accuracy of temperature, flow rate, and oxygen concentration of HFNC, as well as its humidification capacity. We also investigated how the clinical staff of different professions made decisions on HFNC evaluation indicators. Based on the results of the questionnaire survey of clinicians with rich experience in using HFNC, the relative weights of temperature accuracy, flow velocity accuracy, oxygen concentration accuracy, and humidification ability of HFNC equipment were calculated by the AHP to establish a clinical evaluation system. Four kinds of common HFNC devices were tested and evaluated, and the clinical performance of the four kinds of HFNC devices was evaluated by the new scoring system. Results: A total of 356 clinicians participated in and completed the questionnaire survey. To ensure the reliability of the HFNC evaluation system, we only adopted the questionnaire results of clinicians with rich experience in using HFNCs. Data from 247 questionnaires (80 doctors, 105 nurses, and 62 respiratory therapists [RTs]) were analyzed. A total of 174 participants used HFNC more than once a week; 88.71% of RTs used HFNC ≥ 1 score daily, 62.86% of nurses used HFNC ≥ 1 score daily, and 66.25% of doctors used HFNC ≥ 1 daily. There was no significant difference in the frequency of use between doctors and nurses. Finally, the relative weights of temperature accuracy (0.088), humidification capacity (0.206), flow velocity accuracy (0.311), and oxygen concentration accuracy (0.395) in the HFNC clinical evaluation system were obtained. The relative weights of clinicians with different occupations and the frequency of HFNC use were obtained. After testing four kinds of HFNC devices through the evaluation system, it was found that the four kinds of HFNC devices have different advantages in different clinical performances, and AiRVO2 has excellent performance with regard to temperature accuracy and humidification ability. HF-75A and NeoHiF-i7 are good at ensuring the stability of oxygen concentration and the accuracy of the flow velocity of the transported gas, while OH-80S is relatively stable in all aspects. Conclusion: The clinical evaluation system of HFNC is based on the weight of the experience of clinical personnel with different medical backgrounds. Although the existing practitioners have different educational backgrounds (academic qualifications, majors), our evaluation system can enhance clinical staff's awareness of HFNC and further optimize the clinical use of HFNC.

Comparison of Global and Regional Compliance-Guided Positive End-Expiratory Pressure Titration on Regional Lung Ventilation in Moderate-to-Severe Pediatric Acute Respiratory Distress Syndrome

Purpose To investigate the difference in the positive end-expiratory pressure (PEEP) selected with chest electrical impedance tomography (EIT) and with global dynamic respiratory system compliance (Crs) in moderate-to-severe pediatric acute respiratory distress syndrome (pARDS). Methods Patients with moderate-to-severe pARDS (PaO2/FiO2 < 200 mmHg) were retrospectively included. On the day of pARDS diagnosis, two PEEP levels were determined during the decremental PEEP titration for each individual using the best compliance (PEEPC) and EIT-based regional compliance (PEEPEIT) methods. The differences of global and regional compliance (for both gravity-dependent and non-dependent regions) under the two PEEP conditions were compared. In addition, the EIT-based global inhomogeneity index (GI), the center of ventilation (CoV), and standard deviation of regional delayed ventilation (RVDSD) were also calculated and compared. Results A total of 12 children with pARDS (5 with severe and 7 with moderate pARDS) were included. PEEPC and PEEPEIT were identical in 6 patients. In others, the differences were only ± 2 cm H2O (one PEEP step). There were no statistical differences in global compliance at PEEPC and PEEPEIT [28.7 (2.84–33.15) vs. 29.74 (2.84–33.47) ml/cm H2O median (IQR), p = 0.028 (the significant level after adjusted for multiple comparison was 0.017)]. Furthermore, no differences were found in regional compliances and other EIT-based parameters measuring spatial and temporal ventilation distributions. Conclusion Although EIT provided information on ventilation distribution, PEEP selected with the best Crs might be non-inferior to EIT-guided regional ventilation in moderate-to-severe pARDS. Further study with a large sample size is required to confirm the finding.

Scoring System to Evaluate the Performance of ICU Ventilators in the Pandemic of COVID-19: A Lung Model Study.

Ventilators in the intensive care units (ICU) are life-support devices that help physicians to gain additional time to cure the patients. The aim of the study was to establish a scoring system to evaluate the ventilator performance in the context of COVID-19. The scoring system was established by weighting the ventilator performance on five different aspects: the stability of pressurization, response to leaks alteration, performance of reaction, volume delivery, and accuracy in oxygen delivery. The weighting factors were determined with analytic hierarchy process (AHP). Survey was sent out to 66 clinical and mechanical experts. The scoring system was built based on 54 valid replies. A total of 12 commercially available ICU ventilators providing non-invasive ventilation were evaluated using the novel scoring system. A total of eight ICU ventilators with non-invasive ventilation mode and four dedicated non-invasive ventilators were tested according to the scoring system. Four COVID-19 phenotypes were simulated using the ASL5000 lung simulator, namely (1) increased airway resistance (IR) (10 cm H2O/L/s), (2) low compliance (LC) (compliance of 20 ml/cmH2O), (3) low compliance plus increased respiratory effort (LCIE) (respiratory rate of 40 and inspiratory effort of 10 cmH2O), (4) high compliance (HC) (compliance of 50 ml/cmH2O). All of the ventilators were set to three combinations of pressure support and positive end-expiratory pressure levels. The data were collected at baseline and at three customized leak levels. Significant inaccuracies and variations in performance between different non-invasive ventilators were observed, especially in the aspect of leaks alteration, oxygen and volume delivery. Some ventilators have stable performance in different simulated phenotypes whereas the others have over 10% scoring differences. It is feasible to use the proposed scoring system to evaluate the ventilator performance. In the COVID-19 pandemic, clinicians should be aware of possible strengths and weaknesses of ventilators.

Lung Recruitment, Individualized PEEP, and Prone Position Ventilation for COVID-19-Associated Severe ARDS: A Single Center Observational Study.

Background: Patients with coronavirus disease 2019 (COVID-19) may develop severe acute respiratory distress syndrome (ARDS). The aim of the study was to explore the lung recruitability, individualized positive end-expiratory pressure (PEEP), and prone position in COVID-19-associated severe ARDS. Methods: Twenty patients who met the inclusion criteria were studied retrospectively (PaO2/FiO2 68.0 ± 10.3 mmHg). The patients were ventilated under volume-controlled mode with tidal volume of 6 mL/kg predicted body weight. The lung recruitability was assessed via the improvement of PaO2, PaCO2, and static respiratory system compliance (Cstat) from low to high PEEP (5-15 cmH2O). Patients were considered recruitable if two out of three parameters improved. Subsequently, PEEP was titrated according to the best Cstat. The patients were turned to prone position for further 18-20 h. Results: For recruitability assessment, average value of PaO2 was slightly improved at PEEP 15 cmH2O (68.0 ± 10.3 vs. 69.7 ± 7.9 mmHg, baseline vs. PEEP 15 cmH2O; p = 0.31). However, both PaCO2 and Cstat worsened (PaCO2: 72.5 ± 7.1 vs. 75.1 ± 9.0 mmHg; p < 0.01. Cstat: 17.5 ± 3.5 vs. 16.6 ± 3.9 ml/cmH2O; p = 0.05). Only four patients (20%) were considered lung recruitable. Individually titrated PEEP was higher than the baseline PEEP (8.0 ± 2.1 cmH2O vs. 5 cmH2O, p < 0.001). After 18-20 h of prone positioning, investigated parameters were significantly improved compared to the baseline (PaO2: 82.4 ± 15.5 mmHg. PaCO2: 67.2 ± 6.4 mmHg. Cstat: 20.6 ± 4.4 ml/cmH2O. All p < 0.001 vs. baseline). Conclusions: Lung recruitability was very low in COVID-19-associated severe ARDS. Individually titrated PEEP and prone positioning might improve lung mechanics and blood gasses.

The use of electrical impedance tomography for individualized ventilation strategy in COVID-19: a case report.

BACKGROUND: Clinical management of COVID-19 requires close monitoring of lung function. While computed tomography (CT) offers ideal way to identify the phenotypes, it cannot monitor the patient response to therapeutic interventions. We present a case of ventilation management for a COVID-19 patient where electrical impedance tomography (EIT) was used to personalize care. CASE PRESENTATION: The patient developed acute respiratory distress syndrome, required invasive mechanical ventilation, and was subsequently weaned. EIT was used multiple times: to titrate the positive end-expiratory pressure, understand the influence of body position, and guide the support levels during weaning and after extubation. We show how EIT provides bedside monitoring of the patient´s response to various therapeutic interventions and helps guide treatments. CONCLUSION: EIT provides unique information that may help the ventilation management in the pandemic of COVID-19.

Monitoring bronchoalveolar lavage with electrical impedance tomography: first experience in a patient with COVID-19.

OBJECTIVE: Patients with the novel coronavirus disease (COVID-19) often have airway secretions that severely compromise ventilation. This study investigates electrical impedance tomography (EIT) monitoring of a therapeutic bronchoalveolar lavage (BAL) in a patient with COVID-19. APPROACH: A patient with COVID-19 developed acute respiratory distress syndrome requiring mechanical ventilation. He received regional BAL to remove mucus in the small airways (20 ml × 5). Regional ventilation changes before BAL, 30 min after and in the following days, were monitored with EIT. MAIN RESULTS: Regional ventilation worsened shortly after BAL and improved in the following days. The improvement of the oxygenation did not exactly match the ventilation improvement, which indicated a possible ventilation/perfusion mismatch. SIGNIFICANCE: Therapeutic BAL might improve regional ventilation for COVID-19 and EIT could be a useful tool at the bedside to monitor the ventilation treatment of COVID-19.