Alveolar Sampling Research Articles

Inadequate (Ax) Transbronchial Lung Transplant Biopsies—Scope and the Potential Contributing Factors

Transbronchial biopsy is the cornerstone for the evaluation of graft function after lung transplant and a standard of care to diagnose acute cellular rejection. However, the yield from these biopsies is variable, with about 15% to 50% of samples being judged as nondiagnostic, leading to additional procedures. The factors contributing to the nondiagnostic sampling have not been delineated, and the discordance in sample assessment between the bronchoscopist and pathologist has not been quantified. A retrospective cohort of patients who had bronchoscopies with biopsies for surveillance and graft assessment at a large-volume transplant center was studied. The occurrence of nondiagnostic alveolar sampling was assessed, and the patient demographics and procedural characteristics were compared with the diagnostic group. We included 128 patients in our study and found the inadequacy rate for alveolar tissue sampling to be 15.5%. The median number of passes made by the bronchoscopist was 9, and the number of samples assessed by the bronchoscopist was 8, with a median of 6 adequate samples identified by the pathologist. The frequency of previous biopsies, history of prior inadequate samples, need for a higher number of pass attempts, presence of airway abnormalities, and the use of general anesthesia increased the odds of inadequate sampling. Patients with the identified factors may be at risk of inadequate sampling on transbronchial biopsies. The bronchoscopist could consider getting additional samples to avoid a nondiagnostic alveolar sample. Further multicenter studies would help to elucidate other contributing factors.

Nonbronchoscopic Bronchoalveolar Lavage Improves Respiratory Culture Accuracy in Critically Ill Patients.

Diagnosis of pneumonia is challenging in critically ill, intubated patients due to limited diagnostic modalities. Endotracheal aspirate (EA) cultures are standard of care in many ICUs; however, frequent EA contamination leads to unnecessary antibiotic use. Nonbronchoscopic bronchoalveolar lavage (NBBL) obtains sterile, alveolar cultures, avoiding contamination. However, paired NBBL and EA sampling in the setting of a lack of gold standard for airway culture is a novel approach to improve culture accuracy and limit antibiotic use in the critically ill patients. We designed a pilot study to test respiratory culture accuracy between EA and NBBL. Adult, intubated patients with suspected pneumonia received concurrent EA and NBBL cultures by registered respiratory therapists. Respiratory culture microbiology, cell counts, and antibiotic prescribing practices were examined. We performed a prospective pilot study at the Cleveland Clinic Main Campus Medical ICU in Cleveland, Ohio for 22 months from May 2021 through March 2023. Three hundred forty mechanically ventilated patients with suspected pneumonia were screened. Two hundred fifty-seven patients were excluded for severe hypoxia (Fio2 ≥ 80% or positive end-expiratory pressure ≥ 12 cm H2O), coagulopathy, platelets less than 50,000, hemodynamic instability as determined by the treating team, and COVID-19 infection to prevent aerosolization of the virus. All 83 eligible patients were enrolled and underwent concurrent EA and NBBL. More EA cultures (42.17%) were positive than concurrent NBBL cultures (26.51%, p = 0.049), indicating EA contamination. The odds of EA contamination increased by eight-fold 24 hours after intubation. EA was also more likely to be contaminated with oral flora when compared with NBBL cultures. There was a trend toward decreased antibiotic use in patients with positive EA cultures if paired with a negative NBBL culture. Alveolar immune cell populations were recovered from NBBL samples, indicating successful alveolar sampling. There were no major complications from NBBL. NBBL is more accurate than EA for respiratory cultures in critically ill, intubated patients. NBBL provides a safe and effective technique to sample the alveolar space for both clinical and research purposes.

Animal science meets agricultural practice: Preliminary results of an innovative technical approach for exhaled breath analysis in cattle under field conditions

In human and veterinary medicine, the search for exhaled volatiles as potential markers for disease detection has gained increasing attention because exhaled breath analysis bears the advantages of being continuous, non-invasive and reveals instantly available results. The aim of this study was to introduce a technical set-up for breath analysis in bovines. The technical set-up allows (i) CO2-controlled sampling and preconcentration of alveolar gas and (ii) direct breath gas analysis via proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) in parallel. While alveolar gas sampling enables the analysis by gas chromatography-mass spectrometry for unequivocal substance identification, PTR-ToF-MS ensures real-time identification of confounding signals within one measurement. Applicability of the system to conscious cattle and reliability of the signals obtained under field conditions were tested at eight dairy farms. This first testing phase in veterinary practice confirmed that the set-up was well tolerated by each of the cows and that reliable measured values (i.e., raw data) were gained at different respiratory rates. Inspiration could be clearly distinguished from expiration, thus providing the basis for excluding ambient air contamination. Consecutive measurements under standardised conditions in two bovines aged 5–6 months revealed effects of time of day, food intake and handling that need to be evaluated in-depth in future studies with larger groups of animals. As result of these proof-of-concept trials, the introduced technical set-up can be recommended for future studies evaluating exhaled markers in cattle. Breath gas analysis offers a new research area in veterinary medicine and is one step forward towards refining large animal studies, even under field conditions.

Usual Interstitial Pneumonia Can Be Detected in Transbronchial Biopsies Using Machine Learning.

Usual interstitial pneumonia (UIP) is the histopathologic hallmark of idiopathic pulmonary fibrosis. Although UIP can be detected by high-resolution computed tomography of the chest, the results are frequently inconclusive, and pathology from transbronchial biopsy (TBB) has poor sensitivity. Surgical lung biopsy may be necessary for a definitive diagnosis. To develop a genomic classifier in tissue obtained by TBB that distinguishes UIP from non-UIP, trained against central pathology as the reference standard. Exome enriched RNA sequencing was performed on 283 TBBs from 84 subjects. Machine learning was used to train an algorithm with high rule-in (specificity) performance using specimens from 53 subjects. Performance was evaluated by cross-validation and on an independent test set of specimens from 31 subjects. We explored the feasibility of a single molecular test per subject by combining multiple TBBs from upper and lower lobes. To address whether classifier accuracy depends upon adequate alveolar sampling, we tested for correlation between classifier accuracy and expression of alveolar-specific genes. The top-performing algorithm distinguishes UIP from non-UIP conditions in single TBB samples with an area under the receiver operator characteristic curve (AUC) of 0.86, with specificity of 86% (confidence interval = 71-95%) and sensitivity of 63% (confidence interval = 51-74%) (31 test subjects). Performance improves to an AUC of 0.92 when three to five TBB samples per subject are combined at the RNA level for testing. Although we observed a wide range of type I and II alveolar-specific gene expression in TBBs, expression of these transcripts did not correlate with classifier accuracy. We demonstrate proof of principle that genomic analysis and machine learning improves the utility of TBB for the diagnosis of UIP, with greater sensitivity and specificity than pathology in TBB alone. Combining multiple individual subject samples results in increased test accuracy over single sample testing. This approach requires validation in an independent cohort of subjects before application in the clinic.

Tetrasiklin HCL Gel 0,7% meningkatkan jumlah sel fbroblas dan mempertebal ligamen periodontal pada sulkus gingiva tikus yang mengalami periodontitis

Periodontal disease is an infectious disease, could be result loose of the teeth. This research is to prove that the applying 0.7% tetracycline hcl gel on rat gingival sulcus result higher number of fibroblasts and collagen synthesis which are marked by the thicker of rat periodontal ligament. The study was a randomized post test only control group design experimental study on 32 white male rats which are inducted by lipopolyssaccaride (LPS) for 8 days. And then rats divided into control group were given placebo, and treatment group were given 0.7% tetracycline HCL gel. On 10th days, the rats were euthanazided for taken mandibula alveolar bone tissue sampling and histological preparations were made by HE (Harris Hematoxylin-Eosin) staining. The data were analyzed using SPSS program processed using Shapiro Wilk for normality test and then continued using independent t-test. The result of this research is the mean number of fibroblasts at treatment group by administration of 0.7% tetracycline HCL gel (148.38±5.11 units) was higher than the control group (113.19±5.39 units). The mean of collagen synthesis was showed by the thickness of periodontal ligamen at group treated 0.7% tetracycline HCL gel (338.65±57.28 µm) was higher than the control group (225.50±45.29 µm). The mean number of fibroblast cell and thickness of periodontal ligament were statistically different (p<0.05). Thus, it is concluded that 0.7% tetracycline HCL gel enhance the number of fibroblasts cell and the thickness of periodontal ligament in rat with periodontal disease.

Erratum to: Evaluation of needle trap micro-extraction and automatic alveolar sampling for point-of-care breath analysis

Erratum to: Evaluation of needle trap micro-extraction and automatic alveolar sampling for point-of-care breath analysis

Evaluation of needle trap micro-extraction and automatic alveolar sampling for point-of-care breath analysis

Needle trap devices (NTDs) have shown many advantages such as improved detection limits, reduced sampling time and volume, improved stability, and reproducibility if compared with other techniques used in breath analysis such as solid-phase extraction and solid-phase micro-extraction. Effects of sampling flow (2-30 ml/min) and volume (10-100 ml) were investigated in dry gas standards containing hydrocarbons, aldehydes, and aromatic compounds and in humid breath samples. NTDs contained (single-bed) polymer packing and (triple-bed) combinations of divinylbenzene/Carbopack X/Carboxen 1000. Substances were desorbed from the NTDs by means of thermal expansion and analyzed by gas chromatography-mass spectrometry. An automated CO2-controlled sampling device for direct alveolar sampling at the point-of-care was developed and tested in pilot experiments. Adsorption efficiency for small volatile organic compounds decreased and breakthrough increased when sampling was done with polymer needles from a water-saturated matrix (breath) instead from dry gas. Humidity did not affect analysis with triple-bed NTDs. These NTDs showed only small dependencies on sampling flow and low breakthrough from 1-5 %. The new sampling device was able to control crucial parameters such as sampling flow and volume. With triple-bed NTDs, substance amounts increased linearly with increasing sample volume when alveolar breath was pre-concentrated automatically. When compared with manual sampling, automatic sampling showed comparable or better results. Thorough control of sampling and adequate choice of adsorption material is mandatory for application of needle trap micro-extraction in vivo. The new CO2-controlled sampling device allows direct alveolar sampling at the point-of-care without the need of any additional sampling, storage, or pre-concentration steps.

Phase-resolved real-time breath analysis during exercise by means of smart processing of PTR-MS data

Separation of inspiratory, mixed expired and alveolar air is indispensable for reliable analysis of VOC breath biomarkers. Time resolution of direct mass spectrometers often is not sufficient to reliably resolve the phases of a breathing cycle. To realise fast on-line breath monitoring by means of direct MS utilising low-fragmentation soft ionisation, a data processing algorithm was developed to identify inspiratory and alveolar phases from MS data without any additional equipment. To test the algorithm selected breath biomarkers (acetone, isoprene, acetaldehyde and hexanal) were determined by means of quadrupole proton transfer reaction mass spectrometry (PTR-MS) in seven healthy volunteers during exercise on a stationary bicycle. The results were compared to an off-line reference method consisting of controlled alveolar breath sampling in Tedlar® bags, preconcentration by solid-phase micro extraction (SPME), separation and identification by GC-MS. Based on the data processing method, quantitative attribution of biomarkers to inspiratory, alveolar and mixed expiratory phases was possible at any time during the experiment, even under respiratory rates up to 60/min. Alveolar concentrations of the breath markers, measured by PTR-MS ranged from 130 to 2,600 ppb (acetone), 10 to 540 ppb (isoprene), 2 to 31 ppb (acetaldehyde), whereas the concentrations of hexanal were always below the limit of detection (LOD) of 3 ppb. There was good correlation between on-line PTR-MS and SPME-GC-MS measurements during phases with stable physiological parameters but results diverged during rapid changes of heart rate and minute ventilation. This clearly demonstrates the benefits of breath-resolved MS for fast on-line monitoring of exhaled VOCs.

Drug detection in breath: effects of pulmonary blood flow and cardiac output on propofol exhalation

Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in an increased CO on propofol breath concentrations and on the correlation between propofol blood and breath concentrations were investigated in seven acutely instrumented pigs. Discontinuous propofol determination in breath by means of alveolar sampling and SPME-GC-MS showed good agreement (R(2)=0.959) with continuous alveolar real-time measurement by means of PTR-MS. In all investigated animals, increasing cardiac output led to a deterioration of the relationship between breath and blood propofol concentrations (R(2)=0.783 for gas chromatography-mass spectrometry and R(2)=0.795 for PTR-MS). Decreasing pulmonary blood flow and cardiac output through banding of the pulmonary artery did not significantly affect the relationship between propofol breath and blood concentrations (R(2)>0.90). Estimation of propofol blood concentrations from exhaled alveolar concentrations seems possible by means of different analytical methods even when cardiac output is decreased. Increases in cardiac output preclude prediction of blood propofol concentration from exhaled concentrations.

Repeatability of the Measurement of Exhaled Volatile Metabolites Using Selected Ion Flow Tube Mass Spectrometry

Selected ion flow tube mass spectrometry, SIFT-MS, has been used to determine the repeatability of the analysis of volatile metabolites within the breath of healthy volunteers, with emphasis on the influence of sampling methodology. Baseline instrument specific coefficients of variability for examined metabolites were as follows: acetone (1%), ammonia (1%), isoprene (2%), propanol (6%), ethanol (7%), acetic acid (7%), and hydrogen cyanide (19%). Metabolite concentration and related product ion count rate were identified as strong determinants of measurement variation. With the exception of ammonia, an orally released metabolite, variability in repeated on-line breath analysis tended to be lower for metabolites of systemic origin. Standardization of sampling technique improved the repeatability of the analysis of selected metabolites. Off-line (bag) alveolar breath sampling, as opposed to mixed (whole) breath sampling, likewise improved the repeatability of the analysis of all metabolites investigated, with the exception of acetic acid. We conclude that SIFT-MS analysis of common volatile metabolites within the breath of healthy volunteers is both reliable and repeatable. For selected metabolites, the finding that repeatability is improved through modification of sampling methodology may have implications in terms of future recommended practices.

Construction and Evaluation of a Versatile ${\hbox {CO}}_{2}$ Controlled Breath Collection Device

Breath gas analysis offers fascinating new opportunities as it is completely noninvasive and provides a unique window to various biochemical processes in the organism. Requirements for clinical application of this innovative technique include on site and point of care applicability. As most analytical methods like sensors are often not fast enough to realize breath-to-breath sampling additional effort is necessary to provide breath samples of well defined and reproducible composition. For that purpose, we built an automatic CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> controlled device from standard industrial components that enables adjustable breath sampling in any phase of expiration. Control of sampling was realized by fast responding infrared CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensors. The electrical signal of these sensors was used to trigger a micro pump and a valve. In order to render the device as versatile as possible direct coupling with sensors as well as continuous or discrete sampling via a sample loop or traps was possible. CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> concentrations, gas flow, and sample volumes were continuously recorded. Reliability and reproducibility of the device were evaluated and compared with an already established and validated manual sampling method. Alveolar concentrations of selected volatile organic compounds (VOCs) were determined in the corresponding samples taken in rest and during treadmill exercise. Substance concentrations of breath biomarkers in the automatically and manually collected alveolar samples were identical. Reliable sampling was possible with the automatic device up to respiratory rates of 40/min. Controlled and versatile alveolar sampling represents an indispensable requirement of application of most analytical methods and sensor technology in breath analysis.

Multibed Needle Trap Devices for on Site Sampling and Preconcentration of Volatile Breath Biomarkers

To facilitate their use in trace gas analysis, the adsorption capacity of needle trap devices (NTDs) was increased by combining three adsorbent materials and increasing total adsorbent amount. The use of 22 gauge needles, application of internally expanding desorptive flow technique without cryofocusation and a new on site alveolar sampling method for NTDs provided sensitivity in the parts per trillion range of VOC concentrations without loosing precision or linearity. LODs were 0.4 ng/L for isoprene, 0.5 ng/L for dimethyl sulphide, 0.9 ng/L for 2-butenal, 1.0 ng/L for hexane, 1.2 ng/L for pentane, 2.3 ng/L for hexanal, 5.3 ng/L for pentanal, and 8.3 ng/L for acetone. R of calibration curves were consistently >0.98. Loss of volatile aldehydes during storage for 7 days was less than 10%. Needle trap devices packed with more than one adsorbent material represent a promising alternative to SPE and SPME for analysis of volatile organic compounds in the low parts per billion/parts per trillion range. Crucial problems of clinical breath analysis concerning sensitivity of analytical methods, limited stability, and decomposition of breath compounds during sampling and storage could be solved.

Soluble triggering receptor expressed on myeloid cells-1 and diagnosis of ventilator-associated pneumonia

Dear Sir: The quest for a reliable diagnostic marker of ventilator-associated pneumonia (VAP) is still ongoing and whether determination of the alveolar concentration of the soluble form of the triggering receptor expressed on myeloid cells (TREM)-1 could be a valuable candidate is debated. Unfortunately, the study reported in this issue of Intensive Care Medicine will just generate further perplexity [1]. First, the presented work is the result of an ancillary study originating from the series reported last year in this same journal [2], which the authors should have clearly acknowledged. This fact raises concerns regarding the quality of the samples’ conservation (since 2001) especially if they have been subject to freeze/thaw cycles that rapidly degrade sTREM-1. Because alveolar sampling was initially not dedicated to sTREM-1 measurement, bronchoalveolar lavage (BAL) fluid was centrifuged at 250g for 10 min, a procedure largely insufficient to eliminate cell particulates that express membranebound TREM-1 (alveolar macrophages or neutrophils): this may have led to artificially increased sTREM-1 concentrations. Second, the effects of previous antibiotherapy of the diagnosis of VAP are not discussed. VAP was diagnosed by the presence of C2% cells containing intracellular organisms (ICO) or quantitative culture of C10 cfu/ml. Although previous antibiotics do not seem to interfere with ICO percentage [2], this is obviously not the case for quantitative cultures. Unfortunately, no data are presented on the number of VAP diagnosed by ICO percentage or quantitative culture: a subset of patients may have been classified as no VAP just because \2% ICO and \10 cfu/ml were observed while antibiotics were given. By the way, we have no idea on the final diagnosis that was retained in the no-VAP patients. Despite the fact that all these limitations by themselves preclude the drawing of any conclusion, another problematic issue must be pointed out. The authors used a commercially available assay, namely the human TREM-1 Quantikine assay from RnD Systems (Minneapolis, USA), to measure sTREM-1 concentrations. It happens that this assay was recalled by RnD systems during the early summer of 2008 because of its inability to properly measure soluble TREM-1 concentration. I want to believe that the authors were not aware of that. Of note, the three studies [3–5] reporting good performances of BAL sTREM-1 measurement in diagnosing VAP used an ELISA technique (Duoset, RnD Systems) different from the one employed in the two studies [1, 6] showing limited sTREM-1 usefulness (Quantikine). It may well be that sTREM-1 measurement will finally prove to be disappointing in diagnosing VAP, but the current study is just not interpretable.

Molecular breath-gas analysis by online mass spectrometry in mechanically ventilated patients: a new software-based method of CO2-controlled alveolar gas monitoring

Analysis of volatile organic compounds (VOCs) in exhaled breath offers diagnostic potential in research and clinical medicine. Mass spectrometry of expiratory air allows VOC measurements in a concentration range from parts per trillion to parts per million. For the reduction of dilution-related measurement errors due to dead space admixture, the precise identification of the end-expiratory phase of expiration is essential. We used a combination of two integrated MS systems consisting of a conventional MS capable of fast CO2 tracing controlling a second, highly sensitive MS for the measurement of VOCs based on ion–molecule-reaction-MS (IMR-MS). This study intended to test the applicability of a software-based method of CO2-controlled alveolar breath-gas sampling in 12 ventilated patients using acetaldehyde, acetone, ethanol and isoprene as target VOCs (IMR-MS compound integration time 500 ms, cycle time 2 ms, measurement time 120 min). CO2-controlled versus mixed inspiratory/expiratory results are as follows: acetaldehyde 71* (61–133) versus 63 (47–87); acetone 544* (208–1174) versus 504 (152–950); ethanol 133 (99–166) versus 123 (108–185); isoprene 118* (69–253) versus 58 (44–112) (values in ppbv as medians with 25–75%; *p < 0.05 versus mixed inspiratory/expiratory values). The applied software-based CO2-controlled sampling method of expiratory air resulted in significant higher concentrations of acetaldehyde, acetone and isoprene.

A novel visually CO2 controlled alveolar breath sampling technique

A crucial issue in the analysis of exhaled breath is the collection of gaseous samples. The analysis of pure alveolar gas is the method of choice if contamination of samples is to be minimized. Monitoring of expired CO2 can be used to identify alveolar gas. The purpose of this study was to evaluate a bed side version of this technique using visual CO2 control by means of a capnometer. 22 mechanically ventilated patients of an ICU were enrolled into the study. Alveolar and mixed expiratory gas, and arterial blood were sampled. PCO2 in blood and gas was determined in a blood gas analyzer. End tidal PCO2 was monitored in all patients by a fast responding main stream capnometry. Taking the gaseous samples was visually synchronized with the expired CO2. Alveolar CO2 contents measured during two different respiratory cycles were identical (p 0.86). The variation of the CO2 content during 10 measurements in one patient was lower than 4%. Arterial PCO2, PCO2 in alveolar gas and end tidal PCO2 showed positive correlation. The visually CO2-controlled sampling technique of alveolar gas is a reliable and reproducible method. It represents an important step in simplifying and standardizing breath analysis.

Membrane conductance in trained and untrained subjects using either steady state or single breath measurements of NO transfer

The aim of this work was to define the relationship between membrane conductance for NO (Dm) and physical activity by using either the steady state NO transfer ( T LNOSS) or the single breath method ( T LNOSB), making the hypothesis that NO transfer is only limited by the membrane. Alterations in T LNOSS with lung volume during tidal ventilation were measured in six subjects at rest and during steady exercise at 30, 60, and 80% of maximal aerobic power (MAP). A fast responding chemoluminescent NO analyser was used. Two calculation methods were used by sampling NO: (1) at mid-tidal volume, (2) in the middle of the alveolar plateau. T LNOSB at rest and maximal oxygen consumption ( V ˙ O 2 max ) were also measured in 18 other subjects. At rest T LNOSS with method 2 was 192% of the value given by method 1. T LNOSS with method 1 increased by 50% with 80% MAP as it did not change with method 2. Method 2 seemed inaccurate. T LNOSB at rest, which is closely related to Dm, was correlated to age and V ˙ O 2 max , T LNO SB = 182 − 1.2 age + 24.3 V ˙ O 2 max ( l min − 1 ) ( p < 0.01, r 2 = 0.72). The T LNOSS and T LNOSB versus lung volume relationships suggest an influence of the breathing pattern on Dm. Dm can be estimated either by these two NO transfer methods, however the use of the T LNOSS method is highly sensitive to the alveolar sampling level. Dm increase during exercise is a function of MAP. Dm at rest decreases with age as it increases with MAP.

American Medical Research Expedition to Mt Everest (AMREE) and Alveolar Gas Sampling – 25 Years On

A review of alveolar gas sampling above 8000m by the 1981 American Medical Research Expedition to Mt Everest (AMREE). Methods 42 samples of alveolar gas were collected in pre-evacuated aluminium canisters from three locations – Camp 5 (8050m – 282.5 & 284.7 mmHg), Camp 6 (8400m – 267.1 mmHg) and the summit of Mt Everest (8848m – 253 mmHg). These were subsequently transported back to the laboratory and placed in a pre-evacuated chamber and analyzed in a mass spectrometer. Results Of the 34 samples deemed suitable for analysis, 27 were taken from 8050m (PAO2 = 36.1 mmHg, PACO2 = 11 mmHg, R = 0.78), 3 at 8400m (PAO2 = 36.7 mmHg, PACO2 = 8 mmHg, R = 0.82) and 4 at 8848m (PAO2 = 37.6 mmHg, PACO2 = 7.5 mmHg, R = 1.49). Conclusion The AMREE team rejected the summit value of alveolar PO2 (37.6 mmHg) since the calculated R value was deemed to be too high (1.49) and instead, calculated a new value: 35 mmHg. The small difference between the measured and calculated values (2.6 mmHg) may be explained by the “Lactate Paradox”. By measuring alveolar PO2 and PCO2, together with lactate concentrations, the 2007 Xtreme Expedition to Mt Everest intends to build upon AMREE's pioneering work and clarify this outstanding question.

Alveolar plasminogen activator inhibitor-1 predicts ARDS in aspiration pneumonitis

To test the hypothesis that alveolar plasminogen activator inhibitor-1 (PAI-1) can identify patients with witnessed aspiration at risk for progression to acute respiratory distress syndrome (ARDS). Prospective observational study. Medical intensive care unit in a tertiary care center. Fifty-one patients with witnessed aspiration who had a PaO2/FIO2<300 for a period no less than 4 h from admission. Alveolar fluid sampling was performed within 8 h of intubation via luminal suction of the distal airways using a 13-Fr catheter. Plasma levels were collected simultaneously by venipuncture. Alveolar PAI-1 antigen levels were more than five times higher in those who progressed to ARDS than in those with uncomplicated aspiration pneumonitis (2687+/-1498 ng/ml vs. 587+/-535 ng/ml, respectively; p<0.001), while plasma levels of PAI-1 antigen were not significantly different between the two groups. The measured activity of PAI-1 antigen paralleled the levels observed in both media. A cut-off level of alveolar PAI-1 >1518 ng/ml was found to be 82.4% (56.6%-96.0%) sensitive and 97.1% (84.6%-99.5%) specific in predicting progression to ARDS. There was also a significant inverse relationship between elevation of PAI-1 antigen levels and the degree of lung injury as assessed by the days of unassisted ventilation (r2=0.37; p<0.001). Elevation of alveolar PAI-1 antigen levels postaspiration is the consequence of local rather than systemic activation of the fibrinolytic system. Measurement of alveolar PAI-1 antigen levels can be a useful clinical marker in predicting progression to ARDS after gastric aspiration.

Analysis of Sequential Aliquots of Hypertonic Saline Solution-Induced Sputum From Clinically Stable Patients With Cystic Fibrosis

Sputum induction (SI) is a noninvasive tool for sampling inflamed airways. The purpose of this study was to determine the optimal duration of collection in patients with cystic fibrosis (CF). The hypothesis was that the duration of SI collection would quantitatively and qualitatively alter the content of the induced sputum. In 10 clinically stable patients with CF (mean +/- SD age, 28 +/- 7 years; mean FEV(1), 2.6 +/- 0.7 L), SI was performed with 3% hypertonic saline solution at five time points over 20 min. SI was well tolerated, with an average maximum fall in FEV(1) of 7 +/- 7%. The sample volumes, urea concentrations, interleukin-8 concentrations, total cell counts, and nonsquamous cell counts remained constant (p > 0.05). The percentage of neutrophils decreased from 89 +/- 5% to 86 +/- 4% (p = 0.03), and the percentage of alveolar macrophages increased 5 +/- 2% to 8 +/- 4% (p < 0.01). The mean quantitative microbiological counts of nonmucoid Pseudomonas aeruginosa and Staphylococcus aureus decreased over the 20-min time period each by half a log (p = 0.05 and p < 0.01, respectively). Surfactant protein-A concentration increased from 1.6 +/- 0.3 to 2.4 +/- 0.4 ng/mL (log(10); p < 0.001). We conclude that aliquots of induced sputum are similar in clinically stable patients with CF during 4-min intervals, although there is more alveolar sampling after 20 min. When induced-sputum samples are fractionated for research monitoring of inflammatory or microbiologic indexes, power calculations accounting for these variations over time are required.

Alveolar breath sampling and analysis to assess trihalomethane exposures during competitive swimming training.

Alveolar breath sampling was used to assess trihalomethane (THM) exposures encountered by collegiate swimmers during a typical 2-hr training period in an indoor natatorium. The breath samples were collected at regular intervals before, during, and for 3 hr after a moderately intense training workout. Integrated and grab whole-air samples were collected during the training period to help determine inhalation exposures, and pool water samples were collected to help assess dermal exposures. Resulting breath samples collected during the workout demonstrated a rapid uptake of two THMs (chloroform and bromodichloromethane), with chloroform concentrations exceeding the natatorium air levels within 8 min after the exposure began. Chloroform levels continued to rise steeply until they were more than two times the indoor levels, providing evidence that the dermal route of exposure was relatively rapid and ultimately more important than the inhalation route in this training scenario. Chloroform elimination after the exposure period was fitted to a three compartment model that allowed estimation of compartmental half-lives, resulting minimum bloodborne dose, and an approximation of the duration of elevated body burdens. We estimated the dermal exposure route to account for 80% of the blood chloroform concentration and the transdermal diffusion efficiency from the water to the blood to in excess of 2%. Bromodichloromethane elimination was fitted to a two compartment model which provided evidence of a small, but measurable, body burden of this THM resulting from vigorous swim training. These results suggest that trihalomethane exposures for competitive swimmers under prolonged, high-effort training are common and possibly higher than was previously thought and that the dermal exposure route is dominant. The exposures and potential risks associated with this common recreational activity should be more thoroughly investigated.