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- Buehler, Sarah, et al.
(författare)
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Simultaneous monitoring of intratidal compliance and resistance in mechanically ventilated piglets : A feasibility study in two different study groups
- 2015
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 219, s. 36-42
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Tidskriftsartikel (refereegranskat)abstract
- Compliance measures the force counteracting parenchymal lung distension. In mechanical ventilation, intratidal compliance-volume (C(V))-profiles therefore change depending on PEEP, tidal volume (V-T), and underlying mechanical lung properties. Resistance counteracts gas flow through the airways. Due to anatomical linking between parenchyma and airways, intratidal resistance-volume (R(V))-profiles are hypothesised to change in a non-linear way as well. We analysed respiratory system mechanics in fifteen piglets with lavage-induced lung injury and nine healthy piglets ventilated at different PEEP/V-T-settings. In healthy lungs, R(V)-profiles remained mostly constant and linear at all PEEP-settings whereas the shape of the C(V)-profiles showed an increase toward a maximum followed by a decrease (small PEEP) or volume-dependent decrease (large PEEP). In the lavage group, a large drop in resistance at small volumes and slow decrease toward larger volumes was found for small PEEP/V-T-settings where C(V)-profiles revealed a volume-dependent increase (small PEEP) or a decrease (large PEEP and large VT). R(V)-profiles depend characteristically on PEEP, V-T, and possibly whether lungs are healthy or not. Curved R(V)-profiles might indicate pathological changes in the underlying mechanical lung properties and/or might be a sign of derecruitment.
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- Buehler, S., et al.
(författare)
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The shape of intratidal resistance-volume and compliance-volume curves in mechanical ventilation - an animal study
- 2013
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Ingår i: Biomedizinische Technik (Berlin. Zeitschrift). - : Walter de Gruyter GmbH. - 1862-278X .- 0013-5585. ; 58
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Tidskriftsartikel (refereegranskat)abstract
- In respiratory system mechanics, the shape of the intratidal pulmonary compliance-volume curve can be used to detect atelectasis or overdistension in the mechanically ventilated lung and thus to optimise the ventilator setting in terms of positive end-expiratory pressure (PEEP) and tidal volume (V-T). To this end, a set of shape-categories had been suggested. Furthermore, a characteristic behaviour of the intratidal resistance is expected as a consequence of alveolar recruitment and overdistension of the airways. We inspect the intratidal compliance and resistance profiles in mechanically ventilated pigs and suggest a classification into slope-categories for the resistance profile which could be used in combination with the compliance shape-categories to optimize PEEP and V-T.
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- Jaschinski, U, et al.
(författare)
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Acute perioperative disturbances of renal function : Strategies for prevention and therapy
- 2009
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Ingår i: Anaesthesist. - : Springer Science and Business Media LLC. - 0003-2417 .- 1432-055X. ; 58:8, s. 829-47; quiz 848
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Tidskriftsartikel (refereegranskat)abstract
- The increasing life expectancy in industrial nations leads to an increase in the number of elderly and aged persons treated in hospital. Increasingly more complex operations are being carried out on this group of patients. Renal dysfunction in the preoperative situation increases morbidity and mortality. Acute kidney injury (AKI) is nearly always part of a multi-organ dysfunction syndrome in critically ill patients. The treatment strategy of the AKI should be oriented to the degree of organ dysfunction. However, the stage of organ dysfunction is mostly unknown so that the therapeutically exploitable interval is often missed. The same therapy is practically always used for all patients: administration of fluids and diuretics often under the premise of "the kidneys must be rinsed". A unified classification of the continuation of kidney function disorders using the RIFLE criteria (risk, injury, failure, loss, endstage kidney disease) can assist recognition of early stages of kidney failure in order to react correspondingly with therapeutic measures and to critically question or optimize the use of conservative treatment strategies.
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- Kawati, Rafael, et al.
(författare)
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Change in expiratory flow detects partial endotracheal tube obstruction in pressure-controlled ventilation
- 2006
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Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 103:3, s. 650-657
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Tidskriftsartikel (refereegranskat)abstract
- Only extreme degrees of endotracheal tube (ETT) narrowing can be detected with monitoring of tidal volume (V-T) during pressure-controlled ventilation (PCV). To assess the degree of ETT obstruction in PCV and to compare it to V,, monitoring, we produced 3 levels of partial ETT obstruction in 11 healthy anesthetized piglets using ETTs of 4 different inner diameters (IDs 9.0, 8.0, 7.0, and 6.0 mm). An expiratory flow over volume (<(V)over dot >(e)-V) curve was plotted and the time constant (tau(e)) at 15% of expiration time (T-e) was calculated. We also calculated the fractional volume expired during the first 15% of T-e (V-ex (fract, 15)) and compared those variables to full expiratory V, for each of the 3 obstructions. V-T monitoring failed to detect ETT narrowing. By contrast, V-ex (fract,15) decreased and tau(e)e increased significantly with increasing ETT narrowing (for IDs 9.0, 8.0, 7.0, and 6.0, mean V-ex (fract,15) was 195, 180, 146, and 134 mL respectively and mean tau(e) was 380, 491, 635, 794 ms for IDs 9.0, 8.0, 7.0, and 6.0 respectively). We conclude that when the elastic recoil that drives <(V)over dot >(e) is appropriately considered, analysis of <(V)over dot >(e) and V-ex (fract,15) detects partial ETT obstruction during PCV.
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| 10. |
- Kawati, Rafael, 1967-
(författare)
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Evaluation of Respiratory Mechanics by Flow Signal Analysis : With Emphasis on Detecting Partial Endotracheal Tube Obstruction During Mechanical Ventilation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Evaluating respiratory mechanics during dynamic conditions without interrupting ongoing ventilation and flow, adds to the information obtained from the mechanics derived from static (= no flow) conditions, i.e., the flow signal has the potential to provide information on the properties of the respiratory system (including the tubing system). Hence monitoring the changes in the flow signal during ongoing mechanical ventilation would give information about the dynamic mechanics of the respiratory system. Any change in the mechanics of the respiratory system including the endotracheal tube (ETT) and the ventilatory circuit would affect the shape of the flow signal. Knowledge of the airway pressure distal to the ETT at the carina level (= tracheal pressure) is required for calculating the extra resistive load exerted by the endotracheal tube in order to compensate for it. In a porcine model, the flow signal was used to non-invasively calculate tracheal pressure. There was good agreement between calculated and measured tracheal pressure with different modes of ventilation. However, calculation of tracheal pressure assumes that the inner diameter of the ETT is known, and this assumption is not met if the inner diameter is narrowed by secretions. Flow that passes a narrowed tube is decelerated and this is most pronounced with the high flow of early expiration, yielding a typical time constant over expiratory volume pattern that is easy to recognize during mechanical ventilation. This pattern reliably detected partial endotracheal obstruction during volume and pressure controlled mechanical ventilation. A change in compliance of the respiratory system modifies the elastic recoil and this also affects the rate of the expiratory flow and the shape of its signal. In a porcine model, lung volume gains on the flow signal generated by the heartbeats (cardiogenic oscillations) provided information about the compliance of the respiratory system during ongoing mechanical ventilationIn conclusion analyzing the flow signal during ongoing ventilation can be a cheap, non-invasive and reliable tool to monitor the elastic and resistive properties of the respiratory system including the endotracheal tube.
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