Herpes simplex virus and Cytomegalovirus reactivation among severe ARDS patients under veno-venous ECMO.

BACKGROUND: Herpesviridae reactivation among non-immunocompromised critically ill patients is associated with impaired prognosis, especially during acute respiratory distress syndrome (ARDS). However, little is known about herpes simplex virus (HSV) and Cytomegalovirus (CMV) reactivation occurring in patients with severe ARDS under veno-venous extracorporeal membrane oxygenation (ECMO). We tried to determine the frequency of Herpesviridae reactivation and its impact on patients' prognosis during ECMO for severe ARDS. RESULTS: During a 5-year period, 123 non-immunocompromised patients with a severe ARDS requiring a veno-venous ECMO were included. Sixty-seven patients (54%) experienced HSV and/or CMV reactivation during ECMO course (20 viral co-infection, 40 HSV alone, and 7 CMV alone). HSV reactivation occurred earlier than CMV after the beginning of MV [(6-15) vs. 19 (13-29) days; p < 0.01] and after ECMO implementation [(2-8) vs. 14 (10-20) days; p < 0.01]. In univariate analysis, HSV/CMV reactivation was associated with a longer duration of mechanical ventilation [(22-52.5) vs. 17.5 (9-28) days; p < 0.01], a longer duration of ECMO [15 (10-22.5) vs. 9 (5-14) days; p < 0.01], and a prolonged ICU [29 (19.5-47.5) vs. 16 (9-30) days; p < 0.01] and hospital stay [44 (29-63.5) vs. 24 (11-43) days; p < 0.01] as compared to non-reactivated patients. However, in multivariate analysis, viral reactivation remained associated with prolonged MV only. When considered separately, both HSV and CMV reactivation were associated with a longer duration of MV as compared to non-reactivation patients [29 (19.5-41) and 28 (20.5-37), respectively, vs. 17.5 (9-28) days; p < 0.05]. Co-reactivation patients had a longer duration of MV [58.5 (38-72.3); p < 0.05] and ICU stay [51.5 (32.5-69) vs. 27.5 (17.75-35.5) and 29 (20-30.5), respectively] as compared to patients with HSV or CMV reactivation alone. In multivariate analysis, HSV reactivation remained independently associated with a longer duration of MV and hospital length of stay. CONCLUSIONS: Herpesviridae reactivation is frequent among patients with severe ARDS under veno-venous ECMO and is associated with a longer duration of mechanical ventilation. The direct causative link between HSV and CMV reactivation and respiratory function worsening under ECMO remains to be confirmed.

Determination of reliable lung function parameters in intubated mice.

BACKGROUND: Animal models and, in particular, mice models, are important tools to investigate the pathogenesis of respiratory diseases and to test potential new therapeutic drugs. Lung function measurement is a key step in such investigation. In mice, it is usually performed using forced oscillation technique (FOT), negative pressure-driven forced expiratory (NPFE) and pressure-volume (PV) curve maneuvers. However, these techniques require a tracheostomy, which therefore only allows end-point measurements. Orotracheal intubation has been reported to be feasible and to give reproducible lung function measurements, but the agreement between intubation and tracheostomy generated-data remains to be tested. METHODS: Using the Flexivent system, we measured lung function parameters (in particular, forced vital capacity (FVC), forced expiratory volume in the first 0.1 s (FEV0.1), compliance (Crs) of the respiratory system, compliance (C) measured using PV loop and an estimate of inspiratory capacity (A)) in healthy intubated BALB/cJ mice and C57BL/6 J mice and compared the results with similar measurements performed in the same mice subsequently tracheostomized after intubation, by means of paired comparison method, correlation and Bland-Altman analysis. The feasibility of repetitive lung function measurements by intubation was also tested. RESULTS: We identified parameters that are accurately evaluated in intubated animals (i.e., FVC, FEV0.1, Crs, C and A in BALB/cJ and FVC, FEV0.1, and A in C57BL/6 J). Repetitive lung function measurements were obtained in C57BL/6 J mice. CONCLUSION: This subset of lung function parameters in orotracheally intubated mice is reliable, thereby allowing relevant longitudinal studies.

Ultrasonographic diaphragmatic excursion is inaccurate and not better than the MRC score for predicting weaning-failure in mechanically ventilated patients.

PURPOSE: To assess the ability of diaphragmatic ultrasound (US) to predict weaning failure in mechanically ventilated patients undergoing a first spontaneous breathing trial (SBT). METHODS: During a 4-month period, 67 consecutive patients eligible for a first SBT underwent US measurements of maximal diaphragmatic excursion (MDE) by a right anterior subcostal approach. Weaning failure was defined as either the failure of SBT or the need for resumption of ventilatory support for acute respiratory failure or death within 48h following successful extubation. The accuracy of diaphragmatic ultrasound and the Medical Research Council (MRC) score when predicting weaning failure was assessed via a receiver operating curve analysis. RESULTS: The feasibility rate for the ultrasound measurements was 63%. Mean values of MDE were significantly higher in patients who succeeded at their first weaning attempt (4.1±2.1 versus 3±1.8cm, P=0.04). Using a threshold of MDE≤2.7cm, the sensitivity and specificity of diaphragmatic ultrasound in predicting weaning failure were 59% [39-77%] and 71% [57-82%] with an AUC at 0.65 [0.51-0.78]. There was no significant difference between MDE values and MRC scores for predicting weaning failure (P=0.73). CONCLUSION: A decrease in MDE values may be associated with an unfavourable weaning outcome. Diaphragmatic excursion measured by ultrasound is however unable by itself to predict weaning failure at the bedside of patients undergoing a first spontaneous breathing trial and does not provide any additional value compared to the MRC score.

Vital Capacity Impairment due to Neuromuscular Disease and its Correlation with Diaphragmatic Ultrasound: A Preliminary Study.

The purpose of this pilot study was to evaluate the correlation between diaphragmatic excursion measured by a right sub-costal ultrasound approach and forced vital capacity in patients with amyotrophic lateral sclerosis (ALS) or myotonic dystrophy (MD). All patients referred for pulmonary function testing underwent ultrasonic measurement of diaphragmatic excursion during quiet breathing, voluntary sniffing (Esniff) and forced breathing (EDEmax). Forty-five patients were included, mainly for amyotrophic lateral sclerosis or myotonic dystrophy. There was a significant correlation between EDEmax values and forced vital capacity (FVC) values (r = 0.68 [0.46­0.90], p < 0.0001) and between EDEmax values and percentage of predicted FVC values (r = 0.75 [0.55­0.95], p < 0.0001). At a threshold of EDEmax < 5.5 cm, the sensitivity and specificity of ultrasonic diaphragmatic excursion in predicting FVC ≤ 50% of theoretical values were 100% [66%­100%] and 69% [52%­84%] respectively, without any significant difference between males and females. There was no statistical correlation between maximal inspiratory pressure and Esniff.