The influence of different spontaneous breathing trials on regional ventilation distribution in patients with prolonged mechanical ventilation.

OBJECTIVE: This study aimed to explore the influence of different spontaneous breathing trials (SBTs) on regional ventilation distribution in patients with prolonged mechanical ventilation (PMV). METHODS: A total of 24 patients with PMV were analyzed retrospectively. They received three different SBT modes which are automatic tube compensation (ATC), continuous positive airway pressure (CPAP), and T-piece (TP), over three days, and every SBT lasted two hours. Electrical impedance tomography (EIT) was used to monitor the SBT process and five-minute EIT data from five periods (pre-SBT which is t0, at the beginning and the end of the first hour SBT are t1 and t2, at the beginning and the end of the second hour SBT are t3 and t4) were analyzed. RESULTS: In all PMV patients, the temporal skew of aeration (TSA) values at t3 were significantly different in three SBTs (ATC: 18.18±22.97; CPAP: 20.42±17.01; TP:11.26±11.79; p=0.05). In the weaning success group, TSA (t1) values were significantly different too (ATC: 11.11±13.88; CPAP: 19.09±15.77; TP: 9.09±12.74; p=0.04). In the weaning failure group, TSA (t4) values were significantly different in three SBTs (ATC: 36.67±18.46; CPAP: 15.38±11.69; TP: 17.65±17.93; p=0.04). The patient's inspiratory effort (Global flow index at t1) in patients with weaning failure under CPAP (3.51±4.31) was significantly higher than that in the ATC (1.15±1.47) and TP (0.89±1.28). The SBT mode with the best ventilation uniformity may be the one that activates the respiratory muscles the most which may be the optimal SBT. The SBT mode of most uniform ventilation distribution settings varies from patient to patient. CONCLUSION: The regional ventilation distribution was different for each individual, making the SBT with the best ventilation distribution of patients need to be personalized. EIT is a tool that can be considered for real-time assessment.

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.

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.

Stress ulcer prophylaxis in patients being weaned from the ventilator in a respiratory care center: A randomized control trial.

BACKGROUND/PURPOSE: No data has been available on prophylaxis for stress ulcer development during the process of weaning patients off mechanical ventilators. We conducted a randomized study to evaluate the efficacy of stress ulcer prophylaxis with lansoprazole OD in patients being weaned from mechanical ventilators. METHODS: A total of 120 patients were randomly allocated into two groups using blocked randomization, with 60 patients in each group. Group A was the treatment group, receiving lansoprazole OD 30 mg from a nasogastric tube for 14 days, while Group B, the control group, received no proton pump inhibitors or other medications for treating peptic ulcers. The primary end point of our study was apparent upper gastrointestinal bleeding within 2 weeks of enrollment. RESULTS: Apparent upper gastrointestinal bleeding occurred in zero patients and five patients in Groups A and B, respectively (Group A: 0% vs. Group B: 8.3%, p = 0.057). There was no significant difference between the two groups in ventilator-associated pneumonia (Group A: 6.7% vs. Group B: 10.0%, p = 0.509) and 30-day survival rates (Group A: 96.7% vs. Group B: 100%, p = 0.496). CONCLUSION: Stress ulcer prophylaxis with lansoprazole in patients being weaned from mechanical ventilators led to a lower but not statistically significant incidence of apparent upper gastrointestinal bleeding. There was no significant increase of incidence of ventilator-associated pneumonia in the prophylaxis group. Further larger scale studies are needed to clarify the benefit of stress ulcer prophylaxis in such patients.

Pasteurization is effective against multidrug-resistant bacteria.

BACKGROUND: The emergence and rapid spread of multidrug-resistant isolates causing nosocomial infections, particularly pandrug-resistant Acinetobacter baumannii, pandrug-resistant Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and extended-spectrum beta-lactamase-producing Enterobacteriaceae are of great concern worldwide. METHODS: This study investigated the efficacy of pasteurization against contamination of culture tubes and plastic bags by the above 4 important multidrug-resistant bacteria. A 5-mL bacterial suspension with approximately 10(5) and 10(9) cfu/mL of each organism was inoculated into 3 sets of plastic bags and culture tubes and subjected to pasteurization in a washer at 75 degrees C for 30 minutes. RESULTS: A nearly total eradication was found after pasteurization of these 4 drug-resistant pathogens. CONCLUSION: Pasteurization was highly effective against drug-resistant bacteria. Strict adherence to appropriate infection control management for respiratory circuits is important for reducing the spread of drug-resistant bacteria among ventilator-assisted patients.

Outcome and prognostic factors in critically ill patients with systemic lupus erythematosus: a retrospective study.

INTRODUCTION: Systemic lupus erythematosus (SLE) is an archetypal autoimmune disease, involving multiple organ systems with varying course and prognosis. However, there is a paucity of clinical data regarding prognostic factors in SLE patients admitted to the intensive care unit (ICU). METHODS: From January 1992 to December 2000, all patients admitted to the ICU with a diagnosis of SLE were included. Patients were excluded if the diagnosis of SLE was established at or after ICU admission. A multivariate logistic regression model was applied using Acute Physiology and Chronic Health Evaluation II scores and variables that were at least moderately associated (P < 0.2) with survival in the univariate analysis. RESULTS: A total of 51 patients meeting the criteria were included. The mortality rate was 47%. The most common cause of admission was pneumonia with acute respiratory distress syndrome. Multivariate logistic regression analysis showed that intracranial haemorrhage occurring while the patient was in the ICU (relative risk = 18.68), complicating gastrointestinal bleeding (relative risk = 6.97) and concurrent septic shock (relative risk = 77.06) were associated with greater risk of dying, whereas causes of ICU admission and Acute Physiology and Chronic Health Evaluation II score were not significantly associated with death. CONCLUSION: The mortality rate in critically ill SLE patients was high. Gastrointestinal bleeding, intracranial haemorrhage and septic shock were significant prognostic factors in SLE patients admitted to the ICU.

Comparison of the clinical manifestations of severe acute respiratory syndrome and Mycoplasma pneumoniae pneumonia.

BACKGROUND AND PURPOSE: The clinical manifestations of severe acute respiratory syndrome (SARS) and mycoplasma pneumonia are similar. However, administration of corticosteroid to Mycoplasma pneumoniae patients suspected of having SARS may unnecessarily increase the risk of opportunistic infection. We compared the clinical course of 13 SARS patients and 6 patients with mycoplasma pneumonia treated during the outbreak of SARS in Taiwan. METHODS: Patients admitted due to suspicion of SARS with a subsequent diagnosis of SARS or Mycoplasma pneumoniae pneumonia were included. RESULTS: The initial clinical manifestations were similar in patients with SARS and those with M. pneumoniae infection. However, SARS patients had more severe lymphopenia (p = 0.013) and anemia (p = 0.007), and more persistent pulmonary infiltrates (p = 0.023). Respiratory failure developed in 15.4% of the SARS patients and in none of the M. pneumoniae patients. Recovery from thrombocytopenia was associated with defervescence in 12 SARS patients and radiographic improvement in 6 in the following 5 days. In those with unsatisfactory resolution of the pulmonary infiltrates, corticosteroid therapy was associated with rapid radiographic improvement. CONCLUSIONS: Because of similar initial presentations, differentiating SARS from M. pneumoniae pneumonia is very difficult based on symptomatology. In this series, lymphopenia and anemia were more severe in SARS than in M. pneumoniae infection, and SARS patients had more persistent and more new pulmonary infiltrates after hospitalization.