Noninvasive ventilation (NIV) reduces the rate of endotracheal intubation (ETI) and overall mortality in severe acute exacerbation of COPD (AECOPD) with acute respiratory failure and is increasingly applied in respiratory intermediate care units. However, inadequate patient selection and incorrect management of NIV increase mortality. We aimed to identify factors that predict the outcome of NIV in AECOPD. Also, we looked for factors that influence ventilator settings and duration. A prospective cohort study was undertaken in a respiratory intermediate care unit in an academic medical center between 2016 and 2017. Age, BMI, lung function, arterial pH and pCO2 at admission (t0), at 1–2 h (t1) and 4–6 h (t2) after admission, creatinine clearance, echocardiographic data (that defined left heart dysfunction), mean inspiratory pressure during the first 72 h (mIPAP-72 h) and hours of NIV during the first 72 h (dNIV-72 h) were recorded. Main outcome was NIV failure (i.e., ETI or in-hospital death). Secondary outcomes were in-hospital mortality, length of stay (LOS), duration of NIV (days), mIPAP-72 h, and dNIV-72 h. We included 89 patients (45 male, mean age 67.6 years) with AECOPD that required NIV. NIV failure was 12.4%, and in-hospital mortality was 11.2%. NIV failure was correlated with days of NIV, LOS, in-hospital mortality (p < 0.01), and kidney dysfunction (p < 0.05). In-hospital mortality was strongly associated with days of NIV (OR 1.27, 95%CI: 1.07–1.5, p < 0.01) and with FEV1 (p < 0.05). All other investigated parameters (including left heart dysfunction, dNIV-72 h, mIPAP-72 h, pH, etc.) did not influence NIV failure or mortality. dNIV-72 h and days of NIV were independent predictors of LOS (p < 0.01). Regarding the secondary outcomes, left heart dysfunction and pH at 1-2 h independently predicted NIV duration (dNIV-72 h, p < 0.01), while BMI and baseline pCO2 predicted NIV settings (mIPAP-72 h, p < 0.01). In-hospital mortality and NIV failure were not influenced by BMI, left heart dysfunction, age, nor by arterial blood gas values in the first 6 h of NIV. Patients with severe acidosis and left heart dysfunction required prolonged use of NIV. BMI and pCO2 levels influence the NIV settings in AECOPD regardless of lung function.

Background: Microcalorimetric bacterial growth studies have illustrated that thermograms differ significantly with both culture media and strain. The present contribution examines the possibility of discriminating between certain bacterial strains by microcalorimetry and the qualitative and quantitative contribution of the sample volume to the observed thermograms. Growth patterns of samples of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) were analyzed. Certain features of the thermograms that may serve to distinguish between these bacterial strains were identified. Results: The thermograms of the two bacterial strains with sample volumes ranging from 0.3 to 0.7 ml and same initial bacterial concentration were analyzed. Both strains exhibit a roughly 2-peak shape that differs by peak amplitude and position along the time scale. Seven parameters corresponding to the thermogram key points related to time and heat flow values were proposed and statistically analyzed. The most relevant parameters appear to be the time to reach a heat flow of 0.05 mW (1.67 ± 0.46 h in E. coli vs. 2.99 ± 0.53 h in S. aureus, p < 0.0001), the time to reach the first peak (3.84 ± 0.5 h vs. 5.17 ± 0.49 h, p < 0.0001) and the first peak value (0.19 ± 0.02 mW vs. 0.086 ± 0.012 mW, p < 0.0001). The statistical analysis on 4 parameters of volume-normalized heat flow thermograms showed that the time to reach a volume-normalized heat flow of 0.1 mW/ml (1.75 ± 0.37 h in E. coli vs. 2.87 ± 0.65 h in S. aureus, p < 0.005), the time to reach the first volume-normalized peak (3.78 ± 0.47 h vs. 5.12 ± 0.52 h, p < 0.0001) and the first volume-normalized peak value (0.35 ± 0.05 mW/ml vs. 0.181 ± 0.040 mW/ml, p < 0.0001) seem to be the most relevant. Peakfit® decomposition and analysis of the observed thermograms complements the statistical analysis via quantitative arguments, indicating that: (1) the first peak pertains to a faster, “dissolved oxygen” bacterial growth (where the dissolved oxygen in the initial suspension acts as a limiting factor); (2) the second peak indicates a slower “diffused oxygen” growth that involves transport of oxygen contained in the unfilled part of the microcalorimetric cell; (3) a strictly fermentative growth component may slightly contribute to the observed complex thermal signal. Conclusion: The investigated strains of Staphylococcus aureus and Escherichia coli display, under similar experimental conditions, distinct thermal growth patterns. The two strains can be easily differentiated using a selection of the proposed parameters. The presented Peakfit analysis of the complex thermal signal provides the necessary means for establishing the optimal growth conditions of various bacterial strains. These conditions are needed for the standardization of the isothermal microcalorimetry method in view of its further use in qualitative and quantitative estimation of bacterial growth.

A microcalorimetric study was carried out using a Staphylococcus epidermidis population to determine the reproducibility of bacterial growth and the variability of the results within certain experimental parameters (temperature, bacterial concentration, sample thermal history). Reproducibility tests were performed as series of experiments within the same conditions using either freshly prepared populations or samples kept in cold storage. In both cases, the samples were obtained by serial dilution from a concentrated TSB bacterial inoculum incubated overnight.

Introduction: Vibrating mesh nebuliser (VMN) is an alternative aerosol drug-delivery method that may offer advantages over conventional jet nebuliser (JN) in acute exacerbation of COPD (AECOPD). Despite evidence of improved in-vitro aerosol delivery, clinical evidence demonstrating a meaningful short-term physiological benefit in severe AECOPD is limited. Objective: To compare 30-min spirometric response after salbutamol delivered via Aerogen VMN (A-VMN) vs JN in severe AECOPD. Methods: We performed a pilot single-centre, parallel-group randomised controlled trial in adults admitted with severe AECOPD to a respiratory intermediate care unit. Outcomes were the 30-min change from baseline in FEV1 (ΔFEV1) and FVC (ΔFVC). Patients received salbutamol 5 mg in 2 mL 0.9% saline via A-VMN or JN. FEV1 and FVC were measured on admission (pre-nebulisation) and 30 min post-nebulisation; ΔFEV1 and ΔFVC were compared with Welch’s t-test. Mann–Whitney U test with Hodges–Lehmann (HL) location shift was used for sensitivity analysis (two-sided α=0.05). Results: A total of 19 patients (A-VMN n=8; JN n=11, 11 female, mean age of 66.0 years) were included. Mean (SD) ΔFEV1 was 111 (109) mL with A-VMN vs 14 (63) mL with JN; mean difference (A-VMN–JN) was 98 mL (95% CI 2–193), p=0.045. Mean (SD) ΔFVC was 258 (181) mL vs 70 (177) mL with a mean difference of 187 mL (95% CI 10–365), p=0.040. Sensitivity analysis supported larger ΔFEV1 with A-VMN (HL +90 mL, 95% CI 20–230, p=0.020) but not ΔFVC (HL +180 mL, 95% CI 0–360, p=0.075). Standardised effects were large: Hedges’ g=1.10 for ΔFEV1 (95% CI 0.27–2.35) and g=1.00 for ΔFVC (95% CI 0.29–1.90). Conclusion: A-VMN may yield greater 30-min improvements in FEV1 than JN during severe AECOPD, with a trend toward higher FVC. Larger RCTs are warranted.

Introduction: Noninvasive ventilation (NIV) is recommended in patients with obesity hypoventilation syndrome (OHS) with acute hypercapnic respiratory failure (AHRF). Left heart disease is frequently present in obese patients but its prognostic role in patients with OHS and AHRS is unknown. This study aimed to assess the impact of cardiac dysfunction on the outcome of acute NIV in this clinical setting. Methods: A prospective cohort study was undertaken in a respiratory intermediate care unit in an academic medical center between 2018 and 2019. Clinical characteristics, echocardiographic data (that defined left heart dysfunction), NT-pro BNP levels, hours of NIV during the first 72 hours (dNIV-72h) and other data were recorded. The main outcome was NIV failure. Secondary outcomes were NIV duration and length of hospital stay. Results: 33 patients (20 female, mean age 63 years) with OHS and AHRF were included. 26 patients (78%) had left heart dysfunction. NIV failure was 3.3%, mean LOS was 9 days, mean NIV duration was 5.5 days. The presence of left heart dysfunction increased both dNIV-72h (p<0.01) and the total days of NIV (p<0.05) but did not influence the LOS nor the NIV failure rate. NT-pro BNP levels had no impact on the outcomes. Conclusion: NIV failure rate was not influenced by the presence of left heart dysfunction nor by the NT-pro BNP levels. Patients with left heart dysfunction required prolonged use of NIV.

Esophageal pressure (Pes) measurement provides a practical means of quantifying respiratory effort during invasive mechanical ventilation and can be used as a clinical tool for assessing patients during the weaning trial. There is little data regarding a similar use in patients with acute hypercapnic respiratory failure (AHRF) under NIV. We aimed to investigate the potential utility of Pes measurement in guiding NIV weaning during AHRF due to severe COPD exacerbation. Methods: A prospective cohort study was undertaken in a respiratory intermediate care unit in an academic medical center between 2018 and 2019. We measured ∆Pes daily, and we registered these values together with patient characteristics, ventilatory function, and other data. The outcome was successful NIV weaning as opposed to the need for home NIV. Our objective was to identify Pes characteristics that would correlate with successful NIV weaning or the need to continue NIV at home. Results: We included 15 patients (8 males, mean age 65 years) with severe COPD exacerbation with AHRF requiring NIV. All patients were successfully managed with NIV. 10 patients could be weaned from NIV and had an average decrease in ∆Pes from admission to discharge of 6.2 cmH2O (SD 3.0, p 0.07) with a mean discharge ∆Pes of 9.3 cmH2O (SD 4.1). 5 patients needed home NIV and had a medium decrease of ∆Pes of 2.5 cmH2O (SD 2.7, p 0.2) with a mean discharge ∆Pes of 15.0 (SD 1.0). Mean difference of ∆Pes at discharge between the 2 groups was 5.7 (p 0.08). Conclusion: In patients with severe COPD exacerbation with AHRF that required NIV, a lack of drop in ∆Pes and a higher discharge ∆Pes could predict a need for home NIV.