Impact of gas humidification and nebulizer position under invasive ventilation: preclinical comparative study of regional aerosol deposition.

Successful aerosol therapy in mechanically ventilated patients depends on multiple factors. Among these, position of nebulizer in ventilator circuit and humidification of inhaled gases can strongly influence the amount of drug deposited in airways. Indeed, the main objective was to preclinically evaluate impact of gas humidification and nebulizer position during invasive mechanical ventilation on whole lung and regional aerosol deposition and losses. Ex vivo porcine respiratory tracts were ventilated in controlled volumetric mode. Two conditions of relative humidity and temperature of inhaled gases were investigated. For each condition, four different positions of vibrating mesh nebulizer were studied: (i) next to the ventilator, (ii) right before humidifier, (iii) 15 cm to the Y-piece adapter and (iv) right after the Y-piece. Aerosol size distribution were calculated using cascade impactor. Nebulized dose, lung regional deposition and losses were assessed by scintigraphy using 99mtechnetium-labeled diethylene-triamine-penta-acetic acid. Mean nebulized dose was 95% ± 6%. For dry conditions, the mean respiratory tract deposited fractions reached 18% (± 4%) next to ventilator and 53% (± 4%) for proximal position. For humidified conditions, it reached 25% (± 3%) prior humidifier, 57% (± 8%) before Y-piece and 43% (± 11%) after this latter. Optimal nebulizer position is proximal before the Y-piece adapter showing a more than two-fold higher lung dose than positions next to the ventilator. Dry conditions are more likely to cause peripheral deposition of aerosols in the lungs. But gas humidification appears hard to interrupt efficiently and safely in clinical use. Considering the impact of optimized positioning, this study argues to maintain humidification.

Aerosol delivery during invasive mechanical ventilation: development of a preclinical ex vivo respiratory model for aerosol regional deposition.

In intensive care units, nebulization is a usual route for drug administration to patients under mechanical ventilation (MV). The effectiveness of inhalation devices as well as depositions sites of aerosols for ventilated patients remain poorly documented. In vivo human inhalation studies are scarce due to ethical restrictions because imaging techniques require radioaerosols to assess regional aerosol deposition. Thus, we developed an ex vivo respiratory model under invasive MV for preclinical aerosol deposition studies. The model was composed of ex vivo porcine respiratory tracts. MV was achieved thanks to a tracheal intubation and a medical ventilator under controlled conditions. Respiratory features were studied using analogical sensors. Then regional homogeneity of gas-ventilation was assessed with 81mKrypton scintigraphies. Finally, a proof of concept study for aerosol deposition was performed. Obtained respiratory features as well as gamma-imaging techniques, which demonstrated a homogenous regional ventilation and about 18% ± 4% of the nebulized dose deposited the respiratory tract, were in good agreement with human data available in the literature. This original ex vivo respiratory model provides a feasible, reproducible and cost-effective preclinical tool to achieve aerosol deposition studies under MV.

Changes in critically ill cancer patients' short-term outcome over the last decades: results of systematic review with meta-analysis on individual data.

PURPOSE: The number of averted deaths due to therapeutic advances in oncology and hematology is substantial and increasing. Survival of critically ill cancer patients has also improved during the last 2 decades. However, these data stem predominantly from unadjusted analyses. The aim of this study was to assess the impact of ICU admission year on short-term survival of critically ill cancer patients, with special attention on those with neutropenia. METHODS: Systematic review and meta-analysis of individual data according to the guidelines of meta-analysis of observational studies in epidemiology. DATASOURCE: Pubmed and Cochrane databases. ELIGIBILITY CRITERIA: Adult studies published in English between May 2005 and May 2015. RESULTS: Overall, 7354 patients were included among whom 1666 presented with neutropenia at ICU admission. Median ICU admission year was 2007 (IQR 2004-2010; range 1994-2012) and median number of admissions per year was 693 (IQR 450-1007). Overall mortality was 47.7%. ICU admission year was associated with a progressive decrease in hospital mortality (OR per year 0.94; 95% CI 0.93-0.95). After adjustment for confounders, year of ICU admission was independently associated with hospital mortality (OR for hospital mortality per year: 0.96; 95% CI 0.95-0.97). The association was also seen in patients with neutropenia but not in allogeneic stem cell transplant recipients. CONCLUSION: After adjustment for patient characteristics, severity of illness and clustering, hospital mortality decreased steadily over time in critically ill oncology and hematology patients except for allogeneic stem cell transplant recipients.

Influence of neutropenia on mortality of critically ill cancer patients: results of a meta-analysis on individual data.

BACKGROUND: The study objective was to assess the influence of neutropenia on outcome of critically ill cancer patients by meta-analysis of individual data. Secondary objectives were to assess the influence of neutropenia on outcome of critically ill patients in prespecified subgroups (according to underlying tumor, period of admission, need for mechanical ventilation and use of granulocyte colony stimulating factor (G-CSF)). METHODS: Data sources were PubMed and the Cochrane database. Study selection included articles focusing on critically ill cancer patients published in English and studies in humans from May 2005 to May 2015. For study selection, the study eligibility was assessed by two investigators. Individual data from selected studies were obtained from corresponding authors. RESULTS: Overall, 114 studies were identified and authors of 30 studies (26.3% of selected studies) agreed to participate in this study. Of the 7515 included patients, three were excluded due to a missing major variable (neutropenia or mortality) leading to analysis of 7512 patients, including 1702 neutropenic patients (22.6%). After adjustment for confounders, and taking study effect into account, neutropenia was independently associated with mortality (OR 1.41; 95% CI 1.23-1.62; P = 0.03). When analyzed separately, neither admission period, underlying malignancy nor need for mechanical ventilation modified the prognostic influence of neutropenia on outcome. However, among patients for whom data on G-CSF administration were available (n = 1949; 25.9%), neutropenia was no longer associated with outcome in patients receiving G-CSF (OR 1.03; 95% CI 0.70-1.51; P = 0.90). CONCLUSION: Among 7512 critically ill cancer patients included in this systematic review, neutropenia was independently associated with poor outcome despite a meaningful survival. Neutropenia was no longer significantly associated with outcome in patients treated by G-CSF, which may suggest a beneficial effect of G-CSF in neutropenic critically ill cancer patients. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015026347 . Date of registration: Sept 18 2015.