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  • 1. Buehler, S.
    et al.
    Schumann, S.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lozano, S.
    Guttmann, J.
    The shape of intratidal resistance-volume and compliance-volume curves in mechanical ventilation - an animal study2013In: Biomedizinische Technik (Berlin. Zeitschrift), ISSN 1862-278X, E-ISSN 0013-5585, Vol. 58Article in journal (Refereed)
    Abstract [en]

    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.

  • 2.
    Buehler, Sarah
    et al.
    Univ Med Ctr Freiburg, Dept Anesthesiol & Intens Care Med, Div Expt Anesthesiol, Freiburg, Germany..
    Schumann, Stefan
    Univ Med Ctr Freiburg, Dept Anesthesiol & Intens Care Med, Div Expt Anesthesiol, Freiburg, Germany..
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, Josef
    Univ Med Ctr Freiburg, Dept Anesthesiol & Intens Care Med, Div Expt Anesthesiol, Freiburg, Germany..
    Simultaneous monitoring of intratidal compliance and resistance in mechanically ventilated piglets: A feasibility study in two different study groups2015In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 219, p. 36-42Article in journal (Refereed)
    Abstract [en]

    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.

  • 3. Deetjen, P
    et al.
    Lichtwarck-Aschoff, M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Säure-Base-Haushalt aus der Perspektive von P. Stewart: [Interpreting acid-base balance using the Stewart approach.]2007In: Anaesthesist, ISSN 0003-2417, E-ISSN 1432-055X, Vol. 56, no 11, p. 1185-1200Article in journal (Refereed)
    Abstract [en]

    We have used the Stewart approach to typical acute and compensated acid-base disorders here. Dedicated software developed by the author is available with this article and will be of help to anyone considering analyzing his or her own patients using the Stewart approach. The Stewart approach shares analytical steps with the more traditional Siggard-Andersen method, and in most cases the two methods arrive at the same therapeutic solutions. The Stewart approach is, however, more than merely a biophysical appendix to the traditional clinical model, since metabolic acid-base disorders in particular are understood within a completely different pathophysiological framework; this results in a fresh and sometimes unexpectedly helpful perspective that highlights the functional relevance of seemingly forgotten components such as the chloride ion or albumin.

  • 4. Guttmann, J
    et al.
    Haberthur, C
    Mols, G
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Automatic tube compensation (ATC).2002In: Minerva Anestesiol, Vol. 68, p. 369-Article in journal (Refereed)
  • 5.
    Hedenstierna, G
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Lichtwarck-Aschoff, M
    Department of Surgical Sciences.
    Interfacing spontaneous breathing and mechanical ventilation. New insights.2006In: Minerva Anestesiol, ISSN 0375-9393, Vol. 72, no 4, p. 183-98Article in journal (Refereed)
  • 6. Hedlund, A
    et al.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Guttmann, J
    Rubertsson, Sten
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Sjostrand, UH
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Experimental evaulation of procedures to optimize ventilatory strategy in clinical studies of pressure- and volume- controlled ventilation in burn intensive care.1998In: Nordic Burn 98Article, book review (Other academic)
  • 7. Hermle, G
    et al.
    Mols, G
    Zugel, A
    Benzing, A
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Geiger, K
    Guttmann, J
    Intratidal compliance-volume curve as an alternative basis to adjustpositive end-expiratory pressure: a study in isolated perfused rabbitlungs.2002In: Crit Care Med, Vol. 30, p. 1589-Article in journal (Refereed)
  • 8. Jaschinski, U
    et al.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Acute perioperative disturbances of renal function: Strategies for prevention and therapy2009In: Anaesthesist, ISSN 0003-2417, E-ISSN 1432-055X, Vol. 58, no 8, p. 829-47; quiz 848Article in journal (Refereed)
    Abstract [en]

    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.

  • 9. Jaschinski, Ulrich
    et al.
    Ried, Michael
    Lichtwarck-Aschoff, Michael
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Forst, Helmuth
    Bleeding diathesis due to failed antagonism of heparin: successful treatment with recombinant factor VIIa.2004In: Anesth Analg, ISSN 0003-2999, Vol. 99, no 6, p. 1872-Article in journal (Other scientific)
  • 10.
    Kawati, Rafael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lattuada, Marco
    Sjöstrand, Ulf
    Guttmann, Josef
    Hedenstierna, Göran
    Helmer, Alois
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Peak airway pressure increase is late warning sign of partial endotracheal tube obstruction whereas change in expiratory flow is an early warning sign2005In: Anesthesia and Analgesia, Vol. 100, no 3, p. 889-893Article in journal (Refereed)
  • 11.
    Kawati, Rafael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Guttmann, Josef
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Sjöstrand, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Schumann, Stefan
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Change in expiratory flow detects partial endotracheal tube obstruction in pressure-controlled ventilation2006In: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 103, no 3, p. 650-657Article in journal (Refereed)
    Abstract [en]

    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.

  • 12.
    Kawati, Rafael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Sjöstrand, Ulf
    Hedenstierna, Göran
    Guttmann, Josef
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Change in expiratory flow can early detect partial endotracheal tube obstruction in pressure controlled ventilationArticle in journal (Refereed)
  • 13.
    Lichtwarck-Aschoff, M
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    [Notes on the physiology and pathophysiology of cardiac output.]2005In: Anasthesiol Intensivmed Notfallmed Schmerzther, ISSN 0939-2661, Vol. 40, no 10, p. 612-5Article in journal (Refereed)
  • 14.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Deetjen, P.
    Grenzüberschreitungen: Oder: die Glykokalyx unterwegs vom physiologischen Modell zur Klinik2008In: Anaesthesist, ISSN 0003-2417, E-ISSN 1432-055X, Vol. 57, no 10, p. 957-8Article in journal (Refereed)
  • 15.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Dietrich, B
    Breitschaft, D
    Disorders of water and sodium balance in intensive care patients2009In: Anaesthesist, ISSN 0003-2417, E-ISSN 1432-055X, Vol. 58, no 5, p. 543-60; quiz 561Article in journal (Refereed)
    Abstract [en]

    Intensive care patients often suffer from hypo- or hypernatremia. These dysnatremias reflect an antidiuretic-hormone (ADH)-related water imbalance and are the result of the underlying disease. However, they are often triggered by drug side effects and exacerbated by an intentional or unintentional sodium imbalance. Dysnatremias are also caused by artificial ventilation; however, the mechanisms behind this are beyond the scope of this article. Considerations regarding etiology, water and sodium balance and, in particular, the variable in urine dilution or concentration, take priority over a brisk normalization of sodium concentration. Therefore, the 3 most important factors are: 1) delivery of water and sodium to the collecting duct; 2) generation and maintenance of an osmotic pressure gradient exerted by solutes present in the renal medullary interstitium; 3) the regulated water permeability of collecting duct cells under the control of antidiuretic hormone. With these, most disorders can already be identified from patient history and simple factors such as body weight and serum and urine osmolality.

  • 16.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, Josef
    Direct tracheal airway pressure measurements2001In: Acta Anaesthesiol. Scand., Vol. 45, p. 1046-Article in journal (Refereed)
  • 17.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Helmer, Alois
    Kawati, Rafael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lattuada, Marco
    Sjöstrand, Ulf
    Zugel, N
    Guttmann, Josef
    Hedenstierna, Göran
    Good short-term agreement between measured and calculated tracheal pressure2003In: British Journal of Anaesthesia, Vol. 91, no 3, p. 239-248Article in journal (Refereed)
  • 18.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Kessler, V
    Sjöstrand, U H
    Hedlund, A
    Mols, G
    Rubertsson, Sten
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Markström, A M
    Guttmann, J
    Static versus dynamic respiratory mechanics for setting the ventilator.2000In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 85, no 4, p. 577-86Article in journal (Refereed)
    Abstract [en]

    The lower inflection point (LIP) of the inspiratory limb of a static pressure-volume (PV) loop is assumed to indicate the pressure at which most lung units are recruited. The LIP is determined by a static manoeuvre with a PV-history that is different from the PV-history of the actual ventilation. In nine surfactant-deficient piglets, information to allow setting PEEP and VT was obtained, both from the PV-curve and also during ongoing ventilation from the dynamic compliance relationship. According to LIP, PEEP was set at 20 (95% confidence interval 17-22) cm H2O. Volume-dependent dynamic compliance suggested a PEEP reduction (to 15 (13-18) cm H2O). Pulmonary gas exchange remained satisfactory and this change resulted in reduced mechanical stress on the respiratory system, indirectly indicated by volume-dependent compliance being consistently great during the entire inspiration.

  • 19.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Mols, Georg
    Hedlund, Anders J
    Kessler, Volker
    Markstrom, Agneta M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Guttmann, Josef
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Sjostrand, Ulf H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Compliance is nonlinear over tidal volume irrespective of positive end-expiratory pressure level in surfactant-depleted piglets.2000In: Am. J. Respir. Crit. Care Med., Vol. 162, p. 2125-Article in journal (Refereed)
  • 20.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Suki, Bela
    Hedlund, Anders
    Sjöstrand, Ulf
    Markström, Agneta
    Kawati, Rafael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Guttmann, Josef
    cardiogenic oscillations reflects decreasing compliance of the respiratory system during long-term ventilation2004In: Journal of Applied physiology, Vol. 96, no 3, p. 879-884Article in journal (Refereed)
  • 21.
    Lichtwarck-Aschoff, Michael
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Suki, Bela
    Hedlund, Anders
    Sjöstrand, Ulf
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Markström, Agneta
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Kawati, Rafael
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Hedenstierna, Göran
    Department of Medical Sciences.
    Guttmann, Josef
    Decreasing size of cardiogenic oscillations reflects decreasing compliance of the respiratory system during long-term ventilation.2004In: J Appl Physiol, ISSN 8750-7587, Vol. 96, no 3, p. 879-84Article in journal (Refereed)
  • 22.
    Markström, Agneta
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedlund, A
    Sjöstrand, U
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Nordgren, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Effects of sustained pressure application on compliance and blood gases inhealthy porcine lungs2001In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 45, no 10, p. 1235-1240Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    Short periods of sustained increase in airway pressures (Press(up)) are believed to re-open lung areas that collapsed upon induction of anaesthesia. Recruitment of alveolar surface is usually assessed in terms of changes in the pressure-volume (PV) curve. The purpose of this study was to analyse PV-curves before and after a Press(up) and to ascertain whether such changes are compatible with the concept of recruitment of lung volume.

    METHODS:

    During ketamine anaesthesia, 12 healthy piglets were subjected to a Press(up) with end-expiratory pressure (PEEP) of 12 cmH2O and end-inspiratory pressure of 40 cmH2O. Before and after Press(up), PV-curves were obtained from a slow insufflation of 630 ml at zero PEEP (ZEEP).

    RESULTS:

    Compliance was non-linear both before and after Press(up) increasing up to 300 ml and sharply decreasing thereafter. After Press(up), the entire compliance curve was shifted to a higher absolute level. Up to 100 ml and a pressure level corresponding to the lower inflection point on the PV-curve (LIP), compliance was higher before Press(up). No effects on blood gases could be observed.

    CONCLUSION:

    If the similar shape of the compliance curve corresponds to a similar chain of re-opening and overdistension events, this would imply that all volume gained by Press(up) is lost within 10 min, without explaining the higher absolute compliance following Press(up). We speculate that a) re-opening of rapidly collapsing small airways determines the initial compliance increase; b) the lower compliance after Press(up) until LIP indicates reduced intratidal re-opening of lung regions; and c) changes in bronchomotor tone induced by Press(up) raise the absolute compliance, with a similar scenario of alveolar and small airway recruitment now taking place but at different degrees of airway stiffness.

  • 23.
    Markström, Agneta
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
    Hedlund, Anders
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Nordgren, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Sjöstrand, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Impact of different inspiratory flow patterns on arterial C02-tension2000In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 105, no 1, p. 17-29Article in journal (Refereed)
    Abstract [en]

    Ventilation with decelerating inspiratory flow is known to reduce the dead space fraction and to decrease PaCO2. Constant inspiratory flow with an end-inspiratory pause (EIP) is also known to increase the removal of CO2. The aim of the study was to elucidate the effect of the pause/no-flow period while both the pattern and rate of inspiratory flow was unchanged, and when the lung was ventilated with sufficient PEEP to prevent end-expiratory collapse. Surfactant depleted piglets were assigned to decelerating or constant inspiratory flow with 24 breaths per minute (bpm) or 12 bpm, or to constant flow, without and with an end-inspiratory pause of 25%. By adding an EIP the total time without active inspiratory flow of the respiratory cycle was kept unchanged. Gas exchange, airway pressures, functional residual capacity (using sulfurhexafluoride) and haemodynamics (thermo-dye indicator dilution technique) were measured. Irrespective of ventilatory frequency, PaCO2 was lower and serial dead space reduced with decelerating flow, compared with constant inspiratory flow. With an end-inspiratory pause added to constant inspiratory flow, serial dead space was reduced but did not decrease PaCO2. The results of this study corroborate the assumption that total time without active inspiratory flow is important for arterial CO2-tension.

  • 24. Mols, G
    et al.
    Hermle, G
    Fries, G
    Benzing, A
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Geiger, K
    Guttmann, J
    Different strategies to keep the lung open: a study in isolated perfusedrabbit lungs.2002In: Crit Care Med, Vol. 30, p. 1598-Article in journal (Refereed)
  • 25. Schumann, S.
    et al.
    Goebel, U.
    Haberstroh, J.
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Schneider, M.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, J.
    Determination of respiratory system mechanics during inspiration and expiration by FLow-controlled EXpiration (FLEX): a pilot study in anesthetized pigs2014In: Minerva Anestesiologica, ISSN 0375-9393, E-ISSN 1827-1596, Vol. 80, no 1, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Background. Differences between inspiratory and expiratory lung mechanics result in the hysteresis of the pressure volume-loop. While hysteresis area is a global parameter describing the difference between inspiration and expiration in mechanics under quasi-static conditions, a detailed analysis of this difference under the dynamic conditions of mechanical ventilation is feasible once inspiratory and expiratory compliance (C-in/C-ex) are determined separately. This requires uncoupling of expiratory flow rate and volume (V). Methods. Five piglets were mechanically ventilated at positive end-expiratory pressure (PEEP) levels ranging from 0 to 15 cmH(2)O. Expiratory flow rate was linearized by a computer-controlled resistor (flow-controlled expiration). The volume-dependent C-in(V) and C-ex(V) profiles were calculated from the tracheal pressure volume-loops. Results. The intratidal curve-progression of C-ex(V) was altogether higher with a steeper slope compared to C-in(V). With increasing positive end-expiratory pressure (PEEP) dynamic hysteresis area decreased and C-ex(V) tended to run more parallel to C-in(V), Conclusion. The relation between inspiratory and expiratory compliance profiles is associated with the hysteresis area and behaves PEEP dependent. Analysing the C-in-C-ex-relation might therefore potentially offer a new approach to titrate PEEP and tidal volume.

  • 26. Schumann, S.
    et al.
    Kessler, V.
    Joerges, S.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, J.
    Respiratory system inertance corresponds to extravascular lung water in surfactant-deficient piglets2008In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 160, no 3, p. 313-9Article in journal (Refereed)
    Abstract [en]

    In various cardio-pulmonary diseases lung mass is considerably increased due to intrapulmonary fluid accumulation, i.e. extravascular lung water (EVLW). Generally, inertance is a physical system parameter that is mass-dependent. We hypothesized that changes in lung mass influence the inertive behavior of the respiratory system. EVLW and intrathoracic blood volume (ITBV) were compared with respiratory system inertance (I(rs)) in four piglets before and after broncho-alveolar lavage (BAL) that induced surfactant deficiency with interstitial edema. EVLW and ITBV were determined using the double-indicator dilution technique, I(rs) by multiple linear regression analysis. Measurements were taken before, and 1 and 2 h after BAL. EVLW increased threefold (from 6.2+/-0.8 mL/kg at baseline to 17.7+/-0.9 mL/kg (p < 0.001) after BAL). I(rs) increased by 35% (from 0.17+/-0.02 to 0.23+/-0.04 cmH(2)O s(2)/L (p = 0.036) after BAL) and was tightly correlated to EVLW (r(2) = 0.95, p < 0.023). ITBV did not change significantly after BAL. We conclude that I(rs) reflects actual changes in lung mass and thus hints at fluid accumulation within the lung.

  • 27. Schumann, S
    et al.
    Messmer, F
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Haberthuer, C
    Guttmann, J
    Cardiogenic oscillations in spontaneous breathing airway signal reflect respiratory system mechanics2011In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 55, no 8, p. 980-986Article in journal (Refereed)
    Abstract [en]

    Background: Heartbeat-related pressure oscillations appear at the airway opening. We investigated whether these cardiogenic oscillations (COS) - extracted from spontaneous breathing signals - reflect the compliance of the respiratory system. Methods: Fifteen volunteers breathed spontaneously at normal or reduced chest wall compliance, i.e. with and without thorax strapping, and at normal or reduced lung compliance, induced by positive end-expiratory pressure (PEEP). COS-related signals were extracted by averaging the flow and pressure curve sections, temporally aligned to the electrocardiogram signal. Results: COS-related airway pressure and flow curves correlated closely for each subject (r(2) =0.97±0.02, P<0.0001). At the unstrapped thorax, the oscillation's amplitudes were 0.07±0.03 cmH(2) O (pressure) and 22±10 ml/s (flow). COS-related pressure amplitudes correlated closely with the ratio of tidal volume divided by pressure amplitude (r(2) =0.88, P<0.001) and furthermore increased with either thorax strapping (P<0.001) or with increasing PEEP (P=0.049). Conclusion: We conclude that COS extracted from the pressure and flow signal reflect the compliance of the respiratory system and could potentially allow estimating respiratory system mechanics during spontaneous breathing.

  • 28. Schumann, S.
    et al.
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, J.
    Dynamic Hysteresis Behaviour of Respiratory System Mechanics2013In: Biomedizinische Technik (Berlin. Zeitschrift), ISSN 1862-278X, E-ISSN 0013-5585, Vol. 58Article in journal (Refereed)
    Abstract [en]

    The static pressure-volume (PV) curve of the respiratory system is characterized by hysteresis behaviour. Determination of separate inspiratory and expiratory compliance is required to analyse this phenomenon during the dynamic situation of mechanical ventilation. In five piglets expiratory flow was linearized (flow-controlled expiration, FLEX) to allow for compliance estimation separately for inspiration and expiration. Expiratory compliance was higher than inspiratory compliance along the entire intratidal course, converging at higher volumes. At higher PEEP levels expiratory and inspiratory compliance tended to run more in parallel. We conclude that the analysis of the separate inspiratory and expiratory compliance profiles allows for indicating unfavourable mechanical ventilation settings.

  • 29. Schumann, Stefan
    et al.
    Burcza, Boris
    Haberthür, Christoph
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, Josef
    Estimating intratidal nonlinearity of respiratory system mechanics: a model study using the enhanced gliding-SLICE method2009In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 30, no 12, p. 1341-1356Article in journal (Refereed)
    Abstract [en]

    In the clinical situation and in most research work, the analysis of respiratory system mechanics is limited to the estimation of single-value compliances during static or quasi-static conditions. In contrast, our SLICE method analyses intratidal nonlinearity under the dynamic conditions of mechanical ventilation by calculating compliance and resistance for six conjoined volume portions (slices) of the pressure-volume loop by multiple linear regression analysis. With the gliding-SLICE method we present a new approach to determine continuous intratidal nonlinear compliance. The performance of the gliding-SLICE method was tested both in computer simulations and in a physical model of the lung, both simulating different intratidal compliance profiles. Compared to the original SLICE method, the gliding-SLICE method resulted in smaller errors when calculating the compliance or pressure course (all p < 0.001) and in a significant reduction of the discontinuity error for compliance determination which was reduced from 12.7 +/- 7.2 cmH(2)O s L(-1) to 0.8 +/- 0.3 cmH(2)O s L(-1) (mathematical model) and from 7.2 +/- 3.9 cmH(2)O s L(-1) to 0.4 +/- 0.2 cmH(2)O s L(-1) (physical model) (all p < 0.001). We conclude that the new gliding-SLICE method allows detailed assessment of intratidal nonlinear respiratory system mechanics without discontinuity error.

  • 30. Schumann, Stefan
    et al.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Haberthuer, Christoph
    Stahl, Claudius A.
    Moeller, Knut
    Guttmann, Josef
    Detection of partial endotracheal tube obstruction by forced pressure oscillations2007In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 155, no 3, p. 227-233Article in journal (Refereed)
    Abstract [en]

    Rapid airway occlusions during mechanical ventilation are followed immediately by high-frequency pressure oscillations. To answer the question if the frequency of forced pressure oscillations is an indicator for partial obstruction of the endotracheal tube (ETT) we performed mathematical simulations and studies in a ventilated physical lung model. Model-derived predictions were evaluated in seven healthy volunteers. Partial ETT obstruction was mimicked by decreasing the inner diameter (ID) of the ETT. In the physical model ETTs of different ID were used. In spontaneously breathing volunteers viscous fluid was applied into the ETT's lumen. According to the predictions derived from mathematical simulations, narrowing of the ETT's ID from 9.0 to 7.0 mm decreased the frequency of the pressure oscillations by 11% while changes of the respiratory system's compliance had no effect. In volunteers, a similar reduction (10.9%) was found when 5 ml fluid were applied. We conclude that analysis of pressure oscillations after flow interruption offers a tool for non-invasive detection of partial ETT obstruction.

  • 31. Schumann, Stefan
    et al.
    Vimlati, Laszlo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Kawati, Rafael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Guttmann, Josef
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Analysis of Dynamic Intratidal Compliance in a Lung Collapse Model2011In: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 114, no 5, p. 1111-1117Article in journal (Refereed)
    Abstract [en]

    Background: For mechanical ventilation to be lung-protective, an accepted suggestion is to place the tidal volume (V-T) between the lower and upper inflection point of the airway pressure-volume relation. The drawback of this approach is, however, that the pressure-volume relation is assessed under quasistatic, no-flow conditions, which the lungs never experience during ventilation. Intratidal nonlinearity must be assessed under real (i.e., dynamic) conditions. With the dynamic gliding-SLICE technique that generates a high-resolution description of intratidal mechanics, the current study analyzed the profile of the compliance of the respiratory system (C-RS).

    Methods: In 12 anesthetized piglets with lung collapse, the pressure-volume relation was acquired at different levels of positive end-expiratory pressure (PEEP: 0, 5, 10, and 15 cm H2O). Lung collapse was assessed by computed tomography and the intratidal course of C-RS using the gliding-SLICE method.

    Results: Depending on PEEP, C-RS showed characteristic profiles. With low PEEP, C-RS increased up to 20% above the compliance at early inspiration, suggesting intratidal recruitment; whereas a profile of decreasing C-RS, signaling overdistension, occurred with V-T > 5 ml/kg and high PEEP levels. At the highest volume range, C-RS was up to 60% less than the maximum. With PEEP 10 cm H2O, C-RS was high and did not decrease before 5 ml/kg V-T was delivered.

    Conclusions: The profile of dynamic C-RS reflects nonlinear intratidal mechanics of the respiratory system. The SLICE analysis has the potential to detect intratidal recruitment and overdistension. This might help in finding a combination of PEEP and V-T level that is protective from a lung-mechanics perspective.

  • 32.
    Vimlati, Laszlo
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Kawati, Rafael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Spontaneous Breathing Improves Shunt Fraction and Oxygenation in Comparison with Controlled Ventilation at a Similar Amount of Lung Collapse2011In: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 113, no 5, p. 1089-1095Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Spontaneous breathing (SB), when allowed during mechanical ventilation (MV), improves oxygenation in different models of acute lung injury. However, it is not known whether oxygenation is improved during mechanically unsupported SB. Therefore, we compared SB without any support with controlled MV at identical tidal volume (V(T)) and respiratory rate (RR) without positive end-expiratory pressure in a porcine lung collapse model.

    METHODS: In 25 anesthetized piglets, stable lung collapse was induced by application of negative pressure, and animals were randomized to either resume SB or to be kept on MV at identical VT (5 mL/kg; 95% confidence interval: 3.8 to 6.4) and RR (65 per minute [57 to 73]) as had been measured during an initial SB period. Oxygenation was assessed by blood gas analysis (n = 15) completed by multiple inert gas elimination technique (n = 8 of the 15) for shunt measurement. In addition, possible lung recruitment was studied with computed tomography of the chest (n = 10).

    RESULTS: After induction of lung collapse, PaO(2)/FIO(2) decreased to 90 mm Hg (76 to 103). With SB, PaO(2)/FIO(2) increased to 235 mm Hg (177 to 293) within 15 minutes, whereas MV at identical VT and RR did not cause any improvement in oxygenation. Intrapulmonary shunt by 45 minutes after induction of lung collapse was lower during SB (SB: 27% [24 to 30] versus MV: 41% [28 to 55]; P = 0.017). Neither SB nor MV reduced collapsed lung areas on computed tomography.

    CONCLUSIONS: SB without any support improves oxygenation and reduces shunt in comparison with MV at identical settings. This seems to be achieved without any major signs of recruitment of collapsed lung regions.

  • 33.
    Vimlati, Laszlo
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Pulmonary shunt is independent of decrease in cardiac output during unsupported spontaneous breathing in the pig2013In: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 118, no 4, p. 914-923Article in journal (Refereed)
    Abstract [en]

    Background: During mechanical ventilation (MV), pulmonary shunt is cardiac output (CO) dependent; however, whether this relationship is valid during unsupported spontaneous breathing (SB) is unknown. The CO dependency of the calculated venous admixture was investigated, with both minor and major shunt, during unsupported SB, MV, and SB with continuous positive airway pressure (CPAP). Methods: In seven anesthetized supine piglets breathing 100% oxygen, unsupported SB, MV (with tidal volume and respiratory rate corresponding to SB), and 8 cm H2O CPAP (airway pressure corresponding to MV) were applied at random. Venous return and CO were reduced by partial balloon occlusion of the inferior vena cava. Measurements were repeated with the left main bronchus blocked, creating a nonrecruitable pulmonary shunt. Results: CO decreased from 4.2 l/min (95% CI, 3.9-4.5) to 2.5 l/min (95% CI, 2.2-2.7) with partially occluded venous return. Irrespective of whether shunt was minor or major, during unsupported SB, venous admixture was independent of CO (slope: minor shunt, 0.5; major shunt, 1.1%.min(-1).l(-1)) and mixed venous oxygen tension. During both MV and CPAP, venous admixture was dependent on CO (slope MV: minor shunt, 1.9; major shunt, 3.5; CPAP: minor shunt, 1.3; major shunt, 2.9% .min(-1).l(-1)) and mixed-venous oxygen tension (coefficient of determination 0.61-0.86 for all regressions). Conclusions: In contrast to MV and CPAP, venous admixture was independent of CO during unsupported SB, and was unaffected by mixed-venous oxygen tension, casting doubt on the role of hypoxic pulmonary vasoconstriction in pulmonary blood flow redistribution during unsupported SB.

  • 34.
    Vimlati, Laszlo
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Spontaneous breathing reduces pulmonary shunt independent of hypoxic vasoconstriction in the lung collapse modelManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Compared with mechanical ventilation (MV), spontaneous breathing (SB) improves oxygenation even without recruiting atelectatic lung areas, probably by redistributing perfusion to well ventilated areas whose alveolar vessels are not compressed by the higher alveolar pressures of MV. We assumed that regional vasoconstriction, presumably hypoxic vasoconstriction (HPV), causes a redistribution of perfusion, and when the vasoconstriction is blocked by sodium nitroprusside (SNP) infusion, pulmonary shunt in the porcine lung collapse model is similar during SB and MV.

    Methods: Lung collapse was induced in 8 piglets by negative pressure application. The animals were allowed both to breathe spontaneously or set to MV at settings matched to SB, in random order. Calculated venous admixture (Qva/Qt), a proxy for pulmonary shunt, was measured, and any vasoconstriction was blocked by SNP infusion. For determining vascular tone, venous return was gradually reduced and cardiac output (CO) over pulmonary perfusion pressure (Pppulm) plots were recorded.

    Results: With SNP, Qva/Qt increased both during MV (from 7.7 to 20.2%, P=0.009) and SB (from 3.5 to 9%, P=0.013) with similar slopes of the Pppulm over CO plot (~1.5 mmHg*min/L), indicating a similar hypoxic response during both conditions.

    Conclusion: Despite attenuating any vasoconstriction, unexpectedly, pulmonary shunt was lower during spontaneous breathing than during MV. This suggests a mechanism active during SB, favorably redistributing pulmonary blood flow and not silenced by SNP.

  • 35.
    Vimláti, Laszlo
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Lichtwarck-Aschoff, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Haemodynamic stability and pulmonary shunt during spontaneous breathing and mechanical ventilation in porcine lung collapse2012In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 56, no 6, p. 748-754Article in journal (Refereed)
    Abstract [en]

    Background

    We investigated the haemodynamic stability of a novel porcine model of lung collapse induced by negative pressure application (NPA). A secondary aim was to study whether pulmonary shunt correlates with cardiac output (CO).

    Methods

    In 12 anaesthetized and relaxed supine piglets, lung collapse was induced by NPA (−50 kPa). Six animals resumed spontaneous breathing (SB) after 15 min; the other six animals were kept on mechanical ventilation (MV) at respiratory rate and tidal volume (VT) that corresponded to SB. All animals were followed for 135 min with blood gas analysis and detailed haemodynamic monitoring.

    Results

    Haemodynamics and gas exchange were stable in both groups during the experiment with arterial oxygen tension (PaO2)/inspired fraction of oxygen (FiO2) and pulmonary artery occlusion pressure being higher, venous admixture (Qva/Qt) and pulmonary perfusion pressure being lower in the SB group. CO was similar in both groups, showing slight decrease over time in the SB group. During MV, Qva/Qt increased with CO (slope: 4.3 %min/l; P < 0.001), but not so during SB (slope: 0.55 %min/l; P = 0.16).

    Conclusions

    This porcine lung collapse model is reasonably stable in terms of haemodynamics for at least 2 h irrespective of the mode of ventilation. SB achieves higher PaO2/FiO2 and lower Qva/Qt compared with MV. During SB, Qva/Qt seems to be less, if at all, affected by CO compared with MV.

  • 36. Wegenius, GA
    et al.
    Sjöstrand, Ulf
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Svensson, BA
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Lichtwarck-Aschoff, M
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Markstrom, A
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Nordgren, KA
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Surgical Sciences.
    Radiological assessments of surfactant depletion lung injury.1996In: Applied Cardiopulmonary Pathophysiology, Vol. 6, p. 119-Article in journal (Refereed)
1 - 36 of 36
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