Pneumologie
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The essential cause for long-term mechanical ventilation with unweanability from respirator is chronic failure of the inspiratory muscles. Principally two different causes exist for chronic respiratory failure: Primary pulmonary diseases with overload or load imbalance of primarily uncompromised respiratory muscles, and neuromuscular diseases with a significant decrease in respiratory muscle capacity. Intermittent nocturnal ventilation (INV) leads to recovery by unloading the respiratory pump. ⋯ Only 4 out of 18 patients continued to be long-term ventilated invasively via tracheostomy. The remaining patients (25 out of 43) showed normoventilation at daytime during the ensuing inpatient phase so they did not need INV. At the time of the patients' referral to our ICU, there was no predictive value regarding the ultimate indication for INV after weaning from respirator.
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Case Reports
[Tracheobronchomegaly (Mounier-Kuhn syndrome): roentgen findings and tracheal stent instrumentation].
Tracheobronchomegaly is a rare disorder of the lower respiratory tract characterised by marked dilatation of the trachea and the central bronchi associated with recurrent respiratory tract infections. However, some patients with tracheobronchomegaly are not detected because the symptoms are overlooked if chest radiographs alone are used for diagnosis. We encountered two cases of tracheobronchomegaly that were not diagnosed by chest radiographic examinations but were shown clearly with CT. We believe that patients with recurrent pulmonary infection must be examined with the use of CT.
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Hyperventilation syndrome is considered an established diagnosis if it is confirmed that the patient's complaints correlate with arterial hypocapnia. In the diagnostic criteria set up by a group in Nijmegen, paCO2 is determined indirectly by measuring the end tidal CO2. Values below 4 kPa measured at rest and 10 or more minutes after deliberate hyperventilation are classified positive diagnostic criteria for hyperventilation syndrome. ⋯ A comparison of the values employed for diagnosing a hyperventilation syndrome (during normal respiration before and 10 and more minutes after hyperventilation) yields a mean difference of 0.39 kPa according to the statistical computation described by Bland and Altman (limits of the range of agreement between 0.98 and -0.18). The end tidal CO2 values measured during the normal respiratory phase as well as 10 and more minutes after hyperventilation, agree well with the arterial values (the arterial values being slightly higher). During and shortly after hyperventilation the values obtained by both methods differ from one another, so that the exact degree of hypocapnia during a hyperventilation period cannot be assessed by measuring the end tidal CO2.
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Ventilatory measurements especially in preterm infants are hampered by the additional apparatus dead space (face mask, pneumotach, shutter, ...). The apparatus dead space can be higher than the physiological dead space and affects gas exchange and blood gases significantly. For lung function testing in premature or term infants a background flow (flow-through technique) is frequently used to eliminate the apparatus dead space. ⋯ The ratio maxVin/VE decreased significantly (p < 0.05) with increasing frequency: from 4.4 +/- 0.8 (f < 40/min); 4.1 +/- 0.7 (f = 40-59/min); 3.8 +/- 0.5 (f = 60-79/min) to 3.4 +/- 0.4 (f > 80/min). With increasing frequency the flow signal becomes sinusoidal and the ratio maxVin/VE tends to pi. Therefore, during tidal breathing the background flow should be at least three but not more than the six times VE to avoid an impairment of measurements.