Marie-Hélène Becquemin

Long-term Outcomes of Pandemic 2009 Influenza A(H1N1)-Associated Severe ARDS

BACKGROUND No data on long-term outcomes of survivors of 2009 influenza A(H1N1) (A[H1N1])-associated ARDS are available. The objective of this study was to compare the 1-year outcomes of survivors of A(H1N1)-associated ARDS, according to use or no use of extracorporeal lung assist (ECLA), using its need as an ARDS severity surrogate. METHODS Survivors of ARDS (12 with ECLA use vs 25 without, corresponding to 75% and 54% of the eligible patients for each group, respectively) selected from the Réseau Européen de Ventilation Artificielle (REVA) registry had previously been healthy, with only pregnancy and/or moderate obesity (BMI ≤ 35 kg/m²) as known risk factors for A(H1N1) infection. Lung function and morphology, health-related quality of life (HRQoL), and psychologic impairment were evaluated. RESULTS At 1 year post-ICU discharge for the ECLA and no-ECLA groups, respectively, 50% and 40% reported significant exertion dyspnea, 83% and 64% had returned to work, and 75% and 64% had decreased diffusion capacity across the blood-gas barrier, despite their near-normal and similar lung function test results. For both groups, exercise test results showed diminished but comparable exercise capacities, with similar alveolar-arterial oxygen gradients at peak exercise, and CT scans showed minor abnormal findings. HRQoL assessed by the 36-Item Short-Form Health Survey was poorer for both groups than for a sex- and age-matched general population group, but without between-group differences. ECLA and no-ECLA group patients, respectively, had symptoms of anxiety (50% and 56%) and depression (28% and 28%) and were at risk for posttraumatic stress disorder (41% and 44%). CONCLUSIONS One year post-ICU discharge, a majority of survivors of A(H1N1)-associated ARDS had minor lung disabilities with diminished diffusion capacities across the blood-gas barrier, and most had psychologic impairment and poorer HRQoL than a sex- and age-matched general population group. ECLA and no-ECLA group patients had comparable outcomes. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT01271842; URL: www.clinicaltrials.gov

Diaphragm pacing improves sleep in patients with amyotrophic lateral sclerosis

Abstract In amyotrophic lateral sclerosis (ALS) patients, respiratory insufficiency is a major burden. Diaphragm conditioning by electrical stimulation could interfere with lung function decline by promoting the development of type 1 muscle fibres. We describe an ancillary study to a prospective, non-randomized trial (NCT00420719) assessing the effects of diaphragm pacing on forced vital capacity (FVC). Sleep-related disturbances being early clues to diaphragmatic dysfunction, we postulated that they would provide a sensitive marker. Stimulators were implanted laparoscopically in the diaphragm close to the phrenic motor point in 18 ALS patients for daily conditioning. ALS functioning score (ALSFRS), FVC, sniff nasal inspiratory pressure (SNIP), and polysomnographic recordings (PSG, performed with the stimulator turned off) were assessed before implantation and after four months of conditioning (n = 14). Sleep efficiency improved (69 ± 15% to 75 ± 11%, p = 0.0394) with fewer arousals and micro-arousals. This occurred against a background of deterioration as ALSFRS-R, FVC, and SNIP declined. There was, however, no change in NIV status or the ALSFRS respiratory subscore, and the FVC decline was mostly due to impaired expiration. Supporting a better diaphragm function, apnoeas and hypopnoeas during REM sleep decreased. In conclusion, in these severe patients not expected to experience spontaneous improvements, diaphragm conditioning improved sleep and there were hints at diaphragm function changes.

Chemosensitivity recovery in Ondine's curse syndrome under treatment with desogestrel

Congenital central hypoventilation syndrome (CCHS), or Ondines curse syndrome, is a rare genetic disorder associated with mutations of the PHOX2B gene. It is characterized by sleep-related life-threatening hypoventilation that requires mechanical ventilation. The ventilatory response to hypercapnia and hypoxia is absent or dramatically reduced. Spontaneous or pharmacologically induced recovery has never been reported. We have fortuitously observed a case of CO(2)-chemosensitivity recovery in a woman with CCHS who took a progestin contraceptive - desogestrel. We hypothesized that the desogestrel could be responsible for this effect. We tested this hypothesis in a second adult patient. Her lack of CO(2)-chemosensitivity was documented 5 months before she was prescribed desogestrel. Three weeks after initiation of the treatment she exhibited a ventilatory and sensory response to hypercapnia. This response persisted 3 weeks later. This is the first documented case of pharmacologically restored chemosensitivity in CCHS. It suggests that a very potent progestin such as desogestrel could unveil latent chemosensitive neural circuits.

Aerosol Delivery and Humidification With the Boussignac Continuous Positive Airway Pressure Device

BACKGROUND: A simple method for effective bronchodilator aerosol delivery while administering continuing continuous positive airway pressure (CPAP) would be useful in patients with severe bronchial obstruction. OBJECTIVE: To assess the effectiveness of bronchodilator aerosol delivery during CPAP generated by the Boussignac CPAP system and its optimal humidification system. METHODS: First we assessed the relationship between flow and pressure generated in the mask with the Boussignac CPAP system. Next we measured the inspired-gas humidity during CPAP, with several humidification strategies, in 9 healthy volunteers. We then measured the bronchodilator aerosol particle size during CPAP, with and without heat-and-moisture exchanger, in a bench study. Finally, in 7 patients with acute respiratory failure and airway obstruction, we measured work of breathing and gas exchange after a β2-agonist bronchodilator aerosol (terbutaline) delivered during CPAP or via standard nebulization. RESULTS: Optimal humidity was obtained only with the heat-and-moisture exchanger or heated humidifier. The heat-and-moisture exchanger had no influence on bronchodilator aerosol particle size. Work of breathing decreased similarly after bronchodilator via either standard nebulization or CPAP, but PaO2 increased significantly only after CPAP aerosol delivery. CONCLUSIONS: CPAP bronchodilator delivery decreases the work of breathing as effectively as does standard nebulization, but produces a greater oxygenation improvement in patients with airway obstruction. To optimize airway humidification, a heat-and-moisture exchanger could be used with the Boussignac CPAP system, without modifying aerosol delivery.

Experimental measurements of particle retention efficiency of filters used to prevent contamination in respiratory devices

Objective: Various types of filters have been designed to prevent cross contamination of ventilation and respiratory devices. The aim of this study was to experimentally measure the retention efficiency of four simple filters (antibacterial and antivirial and seven combined filters (antibacterial and antiviral plus heat and water exchangers). Setting: The respiratory function testing (EFR) central department of a university teaching hospital. Measurements and results: The same aerosol test with a wide range of particle sizes (0.15 to 15 micrometers) was used to compare the retention efficiency of each filter used in various conditions. The particle sizes and the concentration of the aerosol were measured by a laser velocimeter. For all the filters studied, the retention efficiency was found to be higher than 99 %. However some of them let large particles let through. Conclusion: These data, performed in vitro, should be assessed also by further clinical studies.

Influence of diluent volume of colistimethate sodium on aerosol characteristics and pharmacokinetics in ventilator-associated pneumonia caused by MDR bacteria

Objectives Nebulized colistimethate sodium (CMS) can be used to treat ventilator-associated pneumonia caused by MDR bacteria. The influence of the diluent volume of CMS on aerosol delivery has never been studied. The main objectives of the study were to compare aerosol particle characteristics and plasma and urine pharmacokinetics between two diluent volumes in patients treated with nebulized CMS. Methods A crossover study was conducted in eight patients receiving nebulized CMS every 8 h. After inclusion, nebulization started with 4 million international units (MIU) of CMS diluted either in 6 mL (experimental dilution) or in 12 mL (recommended dilution) of normal saline in a random order. For each diluent volume, CMS aerosol particle sizes were measured and plasma and urine samples were collected every 2 h. Nebulization time and stability of colistin in normal saline were assessed. Results The mass median aerodynamic diameters were 1.4 ± 0.2 versus 0.9 ± 0.2 μm (P < 0.001) for 6 and 12 mL diluent volumes, respectively. The plasma area under the concentration-time curve from 0 to 8 h (AUC0-8) of colistinA+B was 6.6 (4.3-17.0) versus 6.7 (3.6-14.0) μg·h/mL (P = 0.461) for each dilution. The total amount of colistin and CMS eliminated in the urine represented, respectively, 17% and 13% of the CMS initially placed in the nebulizer chamber for 6 and 12 mL diluent volumes (P = 0.4). Nebulization time was shorter [66 (58-75) versus 93 (69-136) min, P = 0.042] and colistin stability was better with the 6 mL diluent volume. Conclusions Nebulization with a higher concentration of CMS in saline (4 MIU in 6 mL) decreases nebulization time and improves colistin stability without changing plasma and urine pharmacokinetics or aerosol particle characteristics for lung deposition.