The assessment of the lung weight in vivo is possible with the quantitative computer tomography (qCT) analysis. Especially in acute lung injury (ALI) the knowledge of the lung weight can help to identify the etiology of lung-dysfunction. The current definition of ALI is orientating on parameters such as impaired oxygenation or radiological opacifications. With this definition a heterogeneous group is captured. There might be dysfunction of the lung due to atelectasis or due to edema, both leading to impaired oxygenation. For the clinician it is important to differentiate between atelectasis and edema. For example, in patients with edematous lungs the clinician is focusing on prevention of secondary lung injury whereas in atelectasis the clinician is targeting a more aggressive treatment. The method of qCT has the potential to differentiate atelectasis from edema and could thus provide valuable information for managing trauma patients fulfilling commonly used criteria for ALI. So far a reference value for normal lung weights in ventilated patients is not available. In recent studies the lung weights of ALI-Patients where compared to healthy spontaneous breathing patients. Effects of a positive end expiratory pressure ventilation (PEEP) or possible influence of intravenous fluid substitution were ignored. The aim of this work was define a reference value of normal lung-weights in ventilated trauma patients. To reveal possible effects of PEEP or intravenous fluid substitution on the lung weight we provided a comparison group of spontaneous breathing trauma patients. In this prospective observational study CTs of trauma patients with normal lungs who underwent emergency CT were selected and two subgroups formed for spontaneous breathing (n = 31) and mechanically ventilated patients (n = 44). The decision whether a lung was normal was based on independent reviewers of the CT images. The arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) had to be greater than 400mmHg. Demographic data, ventilation and clinical parameters of each patient where obtained from the patient data management system. In demographic data mechanically ventilated patients did not differ from the spontaneous breathing patients (only significant variation in sex, with a higher male proportion in the ventilated group). Mechanically ventilated patients were ventilated with PEEP of 10 mmHg at the time of the CT acquisition. The PaO2/FiO2 ratio was 550  74 mmHg. Mechanically ventilated patients received significant more intravenous fluid substitution (p = 0.02). The lung weight in mechanically ventilated patients was 873  124 g Standard deviation (SD), in spontaneous breathing patients 866  169 g SD. The validity of our method was reviewed by placing a water filled plastic bottle next to the thorax. The mass was calculated in two ways: by quantitative computed tomography and by the volumetric mass density of water. A deviation of 2% could be shown Our results suggest that lung weights of mechanically ventilated patients with normal lungs do not differ from those of other with normal lungs (Gattinoni 2006, Puybasset 2000). In conclusion, a moderate PEEP neither a moderate intravenous fluid substitution do not affect the lung weight. The lung weights assessed in this work can be used as reference values, especially, for the group of the trauma-associated ALI. With these results it is possible to identify pathological lung weights. Furthermore it gives a tool in identifying the etiology of ALI and therefore it helps the clinician in making the right therapeutic decisions.

The assessment of the lung weight in vivo is possible with the quantitative computer tomography (qCT) analysis. Especially in acute lung injury (ALI) the knowledge of the lung weight can help to identify the etiology of lung-dysfunction. The current definition of ALI is orientating on parameters such as impaired oxygenation or radiological opacifications. With this definition a heterogeneous group is captured. There might be dysfunction of the lung due to atelectasis or due to edema, both leading to impaired oxygenation. For the clinician it is important to differentiate between atelectasis and edema. For example, in patients with edematous lungs the clinician is focusing on prevention of secondary lung injury whereas in atelectasis the clinician is targeting a more aggressive treatment. The method of qCT has the potential to differentiate atelectasis from edema and could thus provide valuable information for managing trauma patients fulfilling commonly used criteria for ALI. So far a reference value for normal lung weights in ventilated patients is not available. In recent studies the lung weights of ALI-Patients where compared to healthy spontaneous breathing patients. Effects of a positive end expiratory pressure ventilation (PEEP) or possible influence of intravenous fluid substitution were ignored. The aim of this work was define a reference value of normal lung-weights in ventilated trauma patients. To reveal possible effects of PEEP or intravenous fluid substitution on the lung weight we provided a comparison group of spontaneous breathing trauma patients. In this prospective observational study CTs of trauma patients with normal lungs who underwent emergency CT were selected and two subgroups formed for spontaneous breathing (n = 31) and mechanically ventilated patients (n = 44). The decision whether a lung was normal was based on independent reviewers of the CT images. The arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) had to be greater than 400mmHg. Demographic data, ventilation and clinical parameters of each patient where obtained from the patient data management system. In demographic data mechanically ventilated patients did not differ from the spontaneous breathing patients (only significant variation in sex, with a higher male proportion in the ventilated group). Mechanically ventilated patients were ventilated with PEEP of 10 mmHg at the time of the CT acquisition. The PaO2/FiO2 ratio was 550  74 mmHg. Mechanically ventilated patients received significant more intravenous fluid substitution (p = 0.02). The lung weight in mechanically ventilated patients was 873  124 g Standard deviation (SD), in spontaneous breathing patients 866  169 g SD. The validity of our method was reviewed by placing a water filled plastic bottle next to the thorax. The mass was calculated in two ways: by quantitative computed tomography and by the volumetric mass density of water. A deviation of 2% could be shown Our results suggest that lung weights of mechanically ventilated patients with normal lungs do not differ from those of other with normal lungs (Gattinoni 2006, Puybasset 2000). In conclusion, a moderate PEEP neither a moderate intravenous fluid substitution do not affect the lung weight. The lung weights assessed in this work can be used as reference values, especially, for the group of the trauma-associated ALI. With these results it is possible to identify pathological lung weights. Furthermore it gives a tool in identifying the etiology of ALI and therefore it helps the clinician in making the right therapeutic decisions.:Bibliografische Beschreibung 3 Abkürzungsverzeichnis 4 Einleitung 6 Gewichtsbestimmungen in der Medizin 6 Quantitative Computertomographie (qCT): Volumen- und Massebestimmung 7 Klinische Anwendung von Analysen des Lungengewichtes 9 Zielsetzung 11 Patienten und Methoden 12 Maschinell beatmete Patienten (maschinell B.) 12 Spontan atmende Patienten (spontan A.) 14 CT-Untersuchung 14 Quantitative CT-Analyse: Segmentierung der CT-Bilder 15 Validierung der Methodik 18 Auswertung der ROI 18 Statistische Analyse 19 Ergebnisse 21 Demographische Daten 21 Ergebnisse der Lungengewichtsanalyse 25 Ergebnisse der Validierung 28 Diskussion 30 Ausblick 40 Zusammenfassung / Abstract 41 Literaturverzeichnis 46