Influence of torso and arm positions on chest examinations by electrical impedance tomography.

Electrical impedance tomography (EIT) is increasingly used in patients suffering from respiratory disorders during pulmonary function testing (PFT). The EIT chest examinations often take place simultaneously to conventional PFT during which the patients involuntarily move in order to facilitate their breathing. Since the influence of torso and arm movements on EIT chest examinations is unknown, we studied this effect in 13 healthy subjects (37 ± 4 years, mean age ± SD) and 15 patients with obstructive lung diseases (72 ± 8 years) during stable tidal breathing. We carried out the examinations in an upright sitting position with both arms adducted, in a leaning forward position and in an upright sitting position with consecutive right and left arm elevations. We analysed the differences in EIT-derived regional end-expiratory impedance values, tidal impedance variations and their spatial distributions during all successive study phases. Both the torso and the arm movements had a highly significant influence on the end-expiratory impedance values in the healthy subjects (p = 0.0054 and p < 0.0001, respectively) and the patients (p < 0.0001 in both cases). The global tidal impedance variation was affected by the torso, but not the arm movements in both study groups (p = 0.0447 and p = 0.0418, respectively). The spatial heterogeneity of the tidal ventilation distribution was slightly influenced by the alteration of the torso position only in the patients (p = 0.0391). The arm movements did not impact the ventilation distribution in either study group. In summary, the forward torso movement and the arms' abduction exert significant effects on the EIT waveforms during tidal breathing. We recommend strict adherence to the upright sitting position during PFT when EIT is used.

Monitoring and treatment of coagulation abnormalities in burn patients. an international survey on current practices.

The magnitude of coagulation abnormalities, and the definition and treatment of coagulopathy in burn patients are inadequately understood and continue to be discussed in the literature. We aimed to analyse physicians' views on monitoring and treating coagulation abnormalities in burn patients. A total of 350 questionnaires were distributed electronically to burn ICU physicians. Participation was voluntary and anonymous. Responses were analysed electronically and comparisons were made according to the region of the ICU or the specialty of the physician. Of the 350 questionnaires distributed, 55 (15.7%) were returned. The majority of burn specialists consider sepsis-induced coagulopathy to be the most frequent coagulopathy in burn patients, and 74.5% declare that they do not use any specific definition/scoring system in their department to detect coagulopathy. The majority of specialists (70.8%) use standard coagulation tests. The most frequent indications for plasma transfusion are massive bleeding (32.8%) and Disseminated Intravascular Coagulation syndrome treatment (20%). The main specific factors reported in our study are cryoprecipitate (23.2%) and fibrinogen concentrate (18.9%). 21.1% of respondents state that they do not use any specific coagulation factor substitution in burn patients. Specific coagulation factor substitution is not a routine practice. The low response rate precludes the generalization of our results.

La définition, l'importance et le traitement des anomalies de la coagulation chez les patients brûlés sont mal connues et font régulièrement l'objet de controverse dans la littérature. Nous avons analysé le point de vue des praticien sur le monitorage et le traitement de ces anomalies. Trois cent cinquante questionnaires ont été envoyés par voie électronique à des médecins travaillant en USI pour brûlés. La participation était volontaire et anonyme. Les réponses ont été comparées en tenant compte de la géographie et de la spécialité du répondant. Cinquante cinq (15,7%) ont été remplis. La majorité des praticiens considèrent que le sepsis est la cause la plus fréquente de coagulopathie chez les brûlés. Les ¾ n'utilisent pas de définition ni de score spécifiques, 70,8% utilisant les tests standard. Les indication le plus fréquentes de transfusion plasmatique (32,8%) sont le saignement massif et la CIVD (20%). Les facteurs spécifiques le plus souvent utilisés sont les cryoprécipités (23,2%) et le fibrinogène (18,9%), et 21,1% des sondés n'utilisent jamais de tels dérivés du sang. L'utilisation en routine de facteurs de coagulation est donc rare chez les brûlologues. Le faible taux de réponse ne permet pas d'inférer ces résultats à la population brûlologique générale.

Detection of crackle events using a multi-feature approach.

The automatic detection of adventitious lung sounds is a valuable tool to monitor respiratory diseases like chronic obstructive pulmonary disease. Crackles are adventitious and explosive respiratory sounds that are usually associated with the inflammation or infection of the small bronchi, bronchioles and alveoli. In this study a multi-feature approach is proposed for the detection of events, in the frame space, that contain one or more crackles. The performance of thirty-five features was tested. These features include thirty-one features usually used in the context of Music Information Retrieval, a wavelet based feature as well as the Teager energy and the entropy. The classification was done using a logistic regression classifier. Data from seventeen patients with manifestations of adventitious sounds and three healthy volunteers were used to evaluate the performance of the proposed method. The dataset includes crackles, wheezes and normal lung sounds. The optimal detection parameters, such as the number of features, were chosen based on a grid search. The performance of the detection was studied taking into account the sensitivity and the positive predictive value. For the conditions tested, the best results were obtained for the frame size equal to 128 ms and twenty-seven features.

Detection of wheezes using their signature in the spectrogram space and musical features.

In this work thirty features were tested in order to identify the best feature set for the robust detection of wheezes. The features include the detection of the wheezes signature in the spectrogram space (WS-SS) and twenty-nine musical features usually used in the context of Music Information Retrieval. The method proposed to detect the signature of wheezes imposes a temporal Gaussian regularization and a reduction of the false positives based on the (geodesic) morphological opening by reconstruction operator. Our dataset contains wheezes, crackles and normal breath sounds. Four selection algorithms were used to rank the features. The performance of the features was asserted having into account the Matthews correlation coefficient (MCC). All the selection algorithms ranked the WS-SS feature as the most important. A significant boost in performance was obtained by using around ten features. This improvement was independent of the selection algorithm. The use of more than ten features only allows for a small increase of the MCC value.

Evaluation of arterial waveform derived variables for an assessment of volume resuscitation in mechanically ventilated burn patients.

OBJECTIVE: The purpose of this study was to assess the usefulness of stroke volume variations to monitor the early fluid resuscitation in mechanically ventilated burn ICU patients. METHODS AND RESULTS: Data of 29 burn patients (APACHE II - 9.8±3.6, SAPS II - 29±5, TBSA - 39.5±14) were prospectively included in this observational study. Hemodynamic parameters were determined using arterial pressure wave analysis for up to 36h after burn. Statistically significant changes in cardiac index (CI), systemic vascular resistance index (SVRI), stroke volume variation (SVV) were recorded during the observation period. There were significant correlations between CI and SVV (r=-0.454, p=0.03), SVV and SVRI (r=0.482, p=0.02) at 16 h postburn; CI and SVV (r=-0.513, p=0.012), SVV and SVRI (r=0.480, p=0.02) at 24 h postburn, CI and SVV at 36 h postburn (r=-0.478, p=0.021). Significant changes in CI (1.9±1 vs. 3.4±0.9), p=0.02 and in SVV (24.9±3 vs. 14.6±2, p=0.01) were observed in patients with low cardiac output state after administration of 10 ml/kg of Ringer lactate. CONCLUSION: Our results suggest that measurement of stroke volume variations by arterial pulse contour analysis is valuable in monitoring volume administration and in predicting volume responsiveness during the early postburn period.

PCT as a diagnostic and prognostic tool in burn patients. Whether time course has a role in monitoring sepsis treatment.

OBJECTIVE: To evaluate the diagnostic and prognostic performance of inflammatory markers for septic and non septic (localized) bacterial infections in patients with severe burn. METHODS AND RESULTS: Data of 145 patients were prospectively included in this study. Serum procalcitonin and other inflammatory markers were measured within 24 h after burn and daily thereafter. Maximum procalcitonin (p=0.004) was independent predictors of outcome in logistic regression analysis. PCT thresholds of 1.5 ng/ml, 0.52 ng/ml and 0.56 ng/ml had adequate sensitivity and specificity to diagnose sepsis, respiratory tract and wound infections respectively. A threshold value of 7.8 ng/ml in PCT concentration on day 3 was associated with the effectiveness of the sepsis treatment with an AUC of 0.86 (95% CI 0.69-1.03, p=0.002). C-reactive protein levels and WBCs showed no significant change over the first 3 days in the patients with successfully treated sepsis (p=0.93). CONCLUSION: The maximum procalcitonin level has prognostic value in burn patients. PCT can be used as a diagnostic tool in patients with infectious complications with or without bacteremia during ICU stay. Daily consecutive PCT measurements may be a valuable tool in monitoring the effectiveness of antibiotic therapy in burn ICU patients.