Monitoring the Efficacy of High-Flow Nasal Cannula Oxygen Therapy in Patients with Acute Hypoxemic Respiratory Failure in the General Respiratory Ward: A Prospective Observational Study.

High-flow nasal cannula (HFNC) is widely used to treat hypoxemic respiratory failure. The effectiveness of HFNC treatment and the methods for monitoring its efficacy in the general ward remain unclear. This prospective observational study enrolled 42 patients who had acute hypoxemic respiratory failure requiring HFNC oxygen therapy in the general adult respiratory ward. The primary outcome was the all-cause in-hospital mortality. Secondary outcomes included the association between initial blood test results and HFNC outcomes. Regional ventilation distributions were monitored in 24 patients using electrical impedance tomography (EIT) after HFNC initiation. Patients with successful HFNC treatment had better in-hospital survival (94%) compared to those with failed HFNC treatment (0%, p < 0.001). Neutrophil-to-lymphocyte ratios of ≥9 were more common in patients with failed HFNC (70%) compared to those with successful HFNC (52%, p = 0.070), and these patients had shorter hospital survival rates after HFNC treatment (p = 0.046, Tarone-Ware test). Patients with successful HFNC treatment had a more central ventilation distribution compared to those with failed HFNC treatment (p < 0.05). Similarly, patients who survived HFNC treatment had a more central distribution compared to those who did not survive (p < 0.001). We concluded that HFNC in the general respiratory ward may be a potential rescue therapy for patients with respiratory failure. EIT can potentially monitor patients receiving HFNC therapy.

Non-ST-segment elevation myocardial infarction with non-obstructive coronary arteries due to a type-A thymoma: A case report.

Introduction: Myocardial infarction with non-obstructive coronary arteries (MINOCA) has become an increasingly recognized subgroup in patients with acute myocardial infarction, with a recent cohort study reporting a prevalence of 8.8%. This report describes a patient who presented with non-ST-segment elevation myocardial infarction (NSTEMI) due to an incidental anterior mediastinal mass. Case presentation: An 80-year-old woman presented to our emergency department with a chief complaint of progressive shortness of breath associated with retrosternal chest pain for one day duration. Computed tomography (CT) angiogram of the chest was conducted, which revealed an anterior mediastinal mass. Upon admission, the patient developed an acute episode of recurrent severe chest pain, which was diagnosed as an NSTEMI. Emergent cardiac catheterization was performed because of unstable vital signs; however, the results showed no evidence of atherosclerotic changes in the major coronary arteries, compatible with the diagnosis of MINOCA. The mediastinal mass was later confirmed to be a type A thymoma on CT-guided biopsy. Conclusion: Myocardial infarction in patent coronary arteries due to an anterior mediastinal mass is rare. Further studies are needed to standardize the diagnosis and management protocols for the potential etiologies of MINOCA.

Mortality in patients with COVID-19 versus non-COVID-19- related acute respiratory distress syndrome: A single center retrospective observational cohort study.

The pathophysiology of coronavirus disease-2019 (COVID-19)-related acute respiratory distress syndrome (ARDS) varies from other pneumonia-related ARDS. We evaluated whether the mortality rates differed for COVID-19 and non-COVID-19-related ARDS in the Asian population in 2021. This single center retrospective observational cohort study included patients with COVID-19 and non-COVID-19-related ARDS that required invasive mechanical ventilation. The primary outcome was all-cause in-hospital mortality. The secondary outcomes included hospital length of stay, ICU length of stay, duration of mechanical ventilation, and ventilator-free days (VFDs) during the first 28 days. A 1:1 propensity score matching was performed to correct potential confounders by age, obesity or not, and ARDS severity. One-hundred-and-sixty-four patients fulfilled the inclusion criteria. After 1:1 propensity score matching, there were 50 patients in each group. The all-cause in-hospital mortality of all patients was 38 (38%), and no significant differences were found between COVID-19 and non-COVID-19-related ARDS (17 [34%) vs. 21 [42%], p = 0.410). Both groups had length of stay (30.0 [20.0-46.0] vs. 27.0 [13.0-45.0] days, p = 0.312), ICU length of stay (19.0 [13.0-35.0] vs. 16.0 [10.0-32.0] days, p = 0.249), length of mechanical ventilation (19.0 [10.0-36.0] vs. 14.0 [9.0-29.0] days, p = 0.488), and ventilator-free days during the first 28 days (5.5 [0.0-17.0] vs. 0.0 [0.0-14.0] days, p = 0.320). Immunocompromised status (Hazard ratio: 3.63; 95% CI: 1.51-8.74, p = 0.004) and progress to severe ARDS (Hazard ratio: 2.92; 95% CI: 1.18-7.22, p = 0.020) were significant in-hospital mortality-related confounders. There were no significant difference in mortality among both groups. Immunocompromised status and progression to severe ARDS are two possible risk factors for patients with ARDS; COVID-19 is not a mortality-related risk exposure.

Is there a need for individualized adjustment of electrode belt position during EIT-guided titration of positive end-expiratory pressure?

Objective. The aim of the present study was to evaluate the variation of tidal volume-to-impedance ratio (VT/ZT) during positive end-expiratory pressure (PEEP) titration with electrical impedance tomography (EIT) measurement.Approach. Forty-two patients with acute respiratory distress syndrome were retrospectively analyzed. An incremental and subsequently a decremental PEEP trial were performed with steps of 2 cm H2O and duration of 2 min per step during volume-controlled ventilation with decelerating flow. EIT measurement was conducted in the 5th intercostal space andVTwas recorded simultaneously. The variation ofVT/ZT(RatioV) was defined as the changes in percentage to average ratio per cm H2O PEEP change. A z-score > 1 was considered as a significant variation and an implication that the measurement plane was inadequate.Main results. TheRatioVof 42 patients was 1.29 ± 0.80%·cm H2O-1. A z-score of 1 corresponded to the variation of 2.09%·cm H2O-1. Seven patients (16.7%) had a z-score > 1 and showed either positive or negative correlation between the volume-to-impedance ratio and PEEP.Significance. Electrode placement at 5th intercostal space might not be ideal for every individual during EIT measurement. Evaluation of volume-to-impedance ratio variation is necessary for patients undergoing maneuvers with wide alteration in absolute lung volume.

Regional air trapping in acute exacerbation of obstructive lung diseases measured with electrical impedance tomography: a feasibility study.

BACKGROUND: Since bronchial abnormalities often exhibit spatial non-uniformity which may be not correctly assessed by conventional global lung function measures, regional information may help to characterize the disease progress. We hypothesized that regional air trapping during mechanical ventilation could be characterized by regional end-expiratory flow (EEF) derived from electrical impedance tomography (EIT). METHODS: Twenty-five patients suffering from chronic obstructive pulmonary disease (COPD grade 3 or 4) or severe asthma with acute exacerbation were examined prospectively. Patients were ventilated under assist-control mode. EIT measurements were conducted before and one hour after inhaled combined corticosteroid and long-acting ß2 agonist, on two consecutive days. Regional EEF was calculated as derivative of relative impedance for every image pixel in the lung regions. The results were normalized to global flow values measured by the ventilator. RESULTS: Regional and global EEF were highly correlated (P<0.00001) and regional effects of medication and disease progression were visible in the regional EEF maps. The sums of regional EEF in lung regions were 3.8 [2.0, 5.1] and 3.6 [1.9, 4.5] L/min in COPD patients before and after medication (median [lower, upper quartiles]; P=0.37). The corresponding values in asthma patients were 3.0 [2.5, 4.2] and 2.2 [1.7, 3.2] L/min (P<0.05). Histograms of regional EEF showed high spatial heterogeneity of EEF before medication. After one day of treatment, the histograms exhibited less heterogeneous and a decrease in EEF level. CONCLUSIONS: Regional EEF characterizes air trapping and intrinsic PEEP, which could provide diagnostic information for monitoring the disease progress during treatment.

The incidence and interpretation of large differences in EIT-based measures for PEEP titration in ARDS patients.

Positive end-expiratory pressure (PEEP) can be titrated by electrical impedance tomography (EIT). The aim of the present study was to examine the performance of different EIT measures during PEEP trials with the aim of identifying "optimum" PEEP and to provide possible interpretations of largely diverging results. After recruitment (maximum plateau pressure 35 cmH2O), decremental PEEP trial with steps of 2 cmH2O and duration of 2 min per step was performed. Ventilation gain and loss, the global inhomogeneity (GI) index, trend of end-expiratory lung impedance (EELI) and regional compliance (Creg) for estimation of overdistension and collapse were calculated. Largely diverging results of PEEP selection among the measures were defined as differences ≥ 4 PEEP steps (i.e. ≥ 8 cmH2O). In 30 ARDS patients we examined so far, 3 patients showed significant differences in PEEP selections. Overdistension and collapse estimation based on Creg tended to select lower PEEP while the GI index and EELI trend suggested higher PEEP settings. Regional inspiration times were heterogeneous indicating that the assumption of a uniform driving pressure in the calculation of Creg may not be valid. Judging by the predominant ventilation distribution in the most dependent regions, these patients were non-recruitable with the applied recruitment method or pressure levels. The existence of differences in the recommended PEEP among the analyzed EIT measures might be an indicator of non-recruitable lungs and heterogeneous airway resistances. In these extreme cases, the largely diverging results may prompt the attending clinician to develop individual ventilation strategies.Clinical Trial Registration Registration number NCT03112512, https://clinicaltrials.gov/ Registered 13 April 2017.

Positive end-expiratory pressure titration with electrical impedance tomography and pressure-volume curve in severe acute respiratory distress syndrome.

BACKGROUND: The study objective was to compare titration of positive end-expiratory pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded pressure-volume loop in severe acute respiratory distress syndrome (ARDS). METHODS: We have designed a prospective study with historical control group. Twenty-four severe ARDS patients (arterial oxygen partial pressure to fractional inspired oxygen ratio, PaO2/FiO2 < 100 mmHg) were included in the EIT group and examined prospectively. Data from another 31 severe ARDS patients were evaluated retrospectively (control group). All patients were receiving medical care under identical general support guidelines and protective mechanical ventilation. The PEEP level selected in the EIT group was the intercept point of cumulated collapse and overdistension percentages curves. In the control group, optimal PEEP was selected 2 cmH2O above the lower inflection point on the static pressure-volume curve. RESULTS: Patients in the EIT group were younger (P < 0.05), and their mean plateau pressure was 1.5 cmH2O higher (P < 0.01). No differences in other baseline parameters such as APACHE II score, PaO2/FiO2, initial PEEP, driving pressure, tidal volume, and respiratory system compliance were found. Two hours after the first PEEP titration, significantly higher PEEP, compliance, and lower driving pressure were found in the EIT group (P < 0.01). Hospital survival rates were 66.7% (16 of 24 patients) in the EIT group and 48.4% (15 of 31) in the control group. Identical rates were found regarding the weaning success rate: 66.7% in the EIT group and 48.4% in the control group. CONCLUSION: In severe ARDS patients, it was feasible and safe to guide PEEP titration with EIT at the bedside. As compared with pressure-volume curve, the EIT-guided PEEP titration may be associated with improved oxygenation, compliance, driving pressure, and weaning success rate. The findings encourage further randomized control study with a larger sample size and potentially less bias in the baseline data. Trial Registration NCT03112512.

Management of adult-onset methylmalonic acidemia with hypotonia and acute respiratory failure: A case report.

RATIONALE: Methylmalonic acidemia (MMA) is an autosomal recessive disease of organic acidemia. PATIENT CONCERNS: We report a 26-year-old male who presented with metabolic acidosis, acute renal failure required hemodialysis and acute respiratory failure required mechanical ventilation support. Progressive hypotonia of muscles made weaning from mechanical ventilator difficult. DIAGNOSES: High level of serum methylmalonic acid and the mut genotype sequences confirmed the diagnosis of this adult-onset MMA. Two mut genotype sequences were found by analyzing all coding exons and exon-intron junctions. One genotype was well documented (Exon 6 Mutation, c. 1280G>A. p. G427D, heterozygous). The other mut genotype sequence had never been reported elsewhere (Intron 6 Novel, c. 1333-13_c. 1333-8delTTTTTC, heterozygous). INTERVENTIONS: Diet modification, medication, regular hemodialysis and physical rehabilitation. Weaning strategy adjusted with help of electrical impedance tomography. OUTCOMES: The muscle power of the patient gradually recovered. Extubation of the patient was successful and he was discharged without oxygen required. LESSONS: This case gives us the lesson that MMA can be newly diagnosed in adult patient. A new mut genotype sequence was discovered. The use of electrical impedance tomography to select a suitable method for inspiratory muscle training was possible and useful.

Regional ventilation redistribution measured by electrical impedance tomography during spontaneous breathing trial with automatic tube compensation.

OBJECTIVE: Automatic tube compensation (ATC) was developed to overcome the flow resistance of endotracheal tube and decrease the imposed work of breathing. Although ATC is used as an evidence-based strategy to predict successful weaning from assisted ventilation, the changes in regional ventilation distribution induced by this technique are not known. We hypothesized that continuous positive airway pressure plus ATC (CPAP + 100%ATC) could reactivate the respiratory muscles in patients with prolonged mechanical ventilation (PMV) more effectively than volume assist-control mandatory ventilation (ACMV). APPROACH: A total of 16 PMV patients were included. Patients were ventilated under volume ACMV mode and subsequently under CPAP + 100%ATC for 50 min. Two periods of 5 min electrical impedance tomography (EIT) data at the end of each mode were analyzed. MAIN RESULTS: Tidal variations of electrical impedance determined by EIT during CPAP + 100%ATC were significantly smaller than during ACMV (p < 0.001), while no significant differences in end-expiratory lung impedance were found. Regional ventilation was distributed significantly more towards dorsal regions during CPAP + 100%ATC as indicated by the EIT-based index center of ventilation (46.2 ± 5.8 during ACMV versus 51.7 ± 6.5 during CPAP + 100%ATC, values in %, p < 0.001). However, the overall degree of ventilation inhomogeneity was not improved as indicated by the global inhomogeneity index (0.42 ± 0.09 during ACMV versus 0.42 ± 0.06 during CPAP + 100%ATC). The onset of ventilation was significantly less delayed during CPAP + 100%ATC in both ventral and dorsal regions as indicated by the ventilation delay index (ACMV versus CPAP + 100%ATC, 53.0 versus 42.6 in ventral; 50.2 versus 39.3 in dorsal regions; values in %, p < 0.001). SIGNIFICANCE: Dorsal redistribution of ventilation and reduction of ventilation delay as identified by EIT indicate that CPAP + 100%ATC was effective in reactivating the respiratory muscles in the PMV patients of the present study.