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Superiority of transcutaneous CO2 over end-tidal CO2 measurement for monitoring respiratory failure in nonintubated patients: A pilot study.

J Crit Care. 2015 Sep 25;

Authors: Lermuzeaux M, Meric H, Sauneuf B, Girard S, Normand H, Lofaso F, Terzi N

Abstract
PURPOSE: Arterial blood gas measurement is frequently performed in critically ill patients to diagnose and monitor acute respiratory failure. At a given metabolic rate, carbon dioxide partial pressure (Paco2) is entirely determined by CO2 elimination through ventilation. Transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring permits a noninvasive and continuous estimation of arterial CO2 tension (Paco2). The accuracy of PtcCO2, however, has not been well studied. To assess the accuracy of different CO2 monitoring methods, we compared PtcCO2 and end-tidal CO2 concentration (EtCO2) to Paco2 measurements in nonintubated intensive care unit (ICU) patients with acute respiratory failure.
METHODS: During a 2-month period, we conducted a prospective observational cohort study in 25 consecutive nonintubated and spontaneously breathing patients admitted to our ICU. Arterial blood gases were measured at study inclusion, 30, 60, and 120 minutes later. At each sampling time, EtCO2 was continuously monitored using a Philips Smart Capnoline Plus, and PtcCO2 was measured using was measured using SenTec device. The aim of the study was to assess agreement between PtcCO2 and Paco2 and between EtCO2 and Paco2 in nonintubated ICU patients with acute respiratory failure. Bland-Altman techniques and Pearson correlation coefficients were used. The differences over time (at 30, 60, and 120 minutes) between Paco2 and EtCO2 and between PtcCO2 and Paco2 were evaluated using 1-way analysis of variance.
RESULTS: Transcutaneous partial pressure of carbon dioxide and Paco2 were well correlated (R = 0.97), whereas the correlation between EtCO2 and Paco2 was poor (R = 0.62) probably due to the presence of an alveolar dead space in a few patients, most notably in the group with chronic obstructive pulmonary disease. The difference over time remained stable for both Paco2 vs EtCO2 (analysis of variance; P = .88) and Paco2 vs PtcCO2 (P = .93).
CONCLUSION: We found large differences between EtCO2 and Paco2 in spontaneously breathing nonintubated ICU patients admitted for acute respiratory failure. Our study argues against the use of EtCO2 monitoring in such patients but raises the possibility that PtcCO2 measurement may provide reasonable estimates of Paco2.

PMID: 26463320 [PubMed - as supplied by publisher]

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Stenotrophomonas maltophilia Infections in Adults: Primary Bacteremia and Pneumonia.

Jundishapur J Microbiol. 2015 Aug;8(8):e23569

Authors: Gokhan Gozel M, Celik C, Elaldi N

Abstract
BACKGROUND: Stenotrophomonas maltophilia is the third most frequent non-fermentative Gram-negative bacilli in nosocomial infections, and usually causes severe infections such as primary bacteremia and pneumonia.
OBJECTIVES: The current study aimed to compare the demographic and clinical characteristics, microbiological findings and final outcomes of the patients with primary bacteremia and nosocomial pneumonia caused by S. maltophilia.
PATIENTS AND METHODS: The current study retrospectively evaluated patients aged 18 years and above with primary bacteremia and nosocomial pneumonia caused by S. maltophilia from January 2006 to December 2013. Medical records of patients, including reports of clinical microbiology and hospital infection control committee, were evaluated.
RESULTS: A total of 71 patients with S. maltophilia nosocomial infections, 35 (49.3%) primary bacteremia and 36 (50.7%) pneumonia, were diagnosed. There were no significant differences in gender, age, and co-morbid diseases, except chronic obstructive pulmonary disease; this infection was significantly higher in patients with pneumonia. A slightly higher 14-day mortality was found in patients with pneumonia, but the difference was not statistically significant. Inappropriate antibiotic use and presence of multiple organ dysfunction syndrome were found as independent risk factors for 14-day mortality in multivariate analysis.
CONCLUSIONS: A slightly higher mortality in patients with pneumonia, caused by S. maltophilia, was strived to explain by advanced age, higher acute physiology and chronic health evaluation (APACHE II) and sepsis related organ failure assessment (SOFA) score, and also higher inappropriate antibiotic use.

PMID: 26468367 [PubMed]

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Integration of electronic nose technology with spirometry: validation of a new approach for exhaled breath analysis.

J Breath Res. 2015;9(4):046001

Authors: de Vries R, Brinkman P, van der Schee MP, Fens N, Dijkers E, Bootsma SK, de Jongh FH, Sterk PJ

Abstract
New 'omics'-technologies have the potential to better define airway disease in terms of pathophysiological and clinical phenotyping. The integration of electronic nose (eNose) technology with existing diagnostic tests, such as routine spirometry, can bring this technology to 'point-of-care'.We aimed to determine and optimize the technical performance and diagnostic accuracy of exhaled breath analysis linked to routine spirometry.Exhaled breath was collected in triplicate in healthy subjects by an eNose (SpiroNose) based on five identical metal oxide semiconductor sensor arrays (three arrays monitoring exhaled breath and two reference arrays monitoring ambient air) at the rear end of a pneumotachograph. First, the influence of flow, volume, humidity, temperature, environment, etc, was assessed. Secondly, a two-centre case-control study was performed using diagnostic and monitoring visits in day-to-day clinical care in patients with a (differential) diagnosis of asthma, chronic obstructive pulmonary disease (COPD) or lung cancer. Breathprint analysis involved signal processing, environment correction based on alveolar gradients and statistics based on principal component (PC) analysis, followed by discriminant analysis (Matlab2014/SPSS20).Expiratory flow showed a significant linear correlation with raw sensor deflections (R(2)  =  0.84) in 60 healthy subjects (age 43  ±  11 years). No correlation was found between sensor readings and exhaled volume, humidity and temperature. Exhaled data after environment correction were highly reproducible for each sensor array (Cohen's Kappa 0.81-0.94).Thirty-seven asthmatics (41  ±  14.2 years), 31 COPD patients (66  ±  8.4 years), 31 lung cancer patients (63  ±  10.8 years) and 45 healthy controls (41  ±  12.5 years) entered the cross-sectional study. SpiroNose could adequately distinguish between controls, asthma, COPD and lung cancer patients with cross-validation values ranging between 78-88%.We have developed a standardized way to integrate eNose technology with spirometry. Signal processing techniques and environmental background correction ensured that the multiple sensor arrays within the SpiroNose provided repeatable and interchangeable results. SpiroNose discriminated controls and patients with asthma, COPD and lung cancer with promising accuracy, paving the route towards point-of-care exhaled breath diagnostics.

PMID: 26469298 [PubMed - in process]