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J J Rouby - One of the best experts on this subject based on the ideXlab platform.

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Qin Lu, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure–volume (P–V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas–tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 ± 22% versus 55  ± 12%, p < 0.05) and the percentage of poor...

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure-volume (P-V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas-tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 +/- 22% versus 55 +/- 12%, p < 0.05) and the percentage of poorly aerated lung was greater (40 +/- 12% versus 23 +/- 8%, p < 0.05) in patients with an LIP than in patients without an LIP. Lung density Histograms of patients with an LIP showed a unimodal distribution with a peak at 7 Hounsfield units (HU). Lung density Histograms of patients without an LIP had a bimodal distribution, with a first peak at -727 HU and a second peak at 27 HU. Total respiratory system and lung compliances were lower in patients with an LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without an LIP. The amount of lung overdistension was related to the volume of lung parenchyma, characterized by a CT number less than -800 HU before PEEP implementation (y = 0.52x + 4, R = 0.87, and p < 0.0001). This study shows that the presence or the absence of an LIP on the lung P-V curve is associated with differences in lung morphology. In patients without an LIP on the lung P-V curve, normally aerated lung areas coexist with nonaerated lung areas and increasing levels of PEEP result in lung overdistension rather than in additional alveolar recruitment. In patients with an LIP, air and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolar recruitment without lung overdistention.

Silvia Regina Rios Vieira - One of the best experts on this subject based on the ideXlab platform.

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Qin Lu, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure–volume (P–V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas–tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 ± 22% versus 55  ± 12%, p < 0.05) and the percentage of poor...

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure-volume (P-V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas-tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 +/- 22% versus 55 +/- 12%, p < 0.05) and the percentage of poorly aerated lung was greater (40 +/- 12% versus 23 +/- 8%, p < 0.05) in patients with an LIP than in patients without an LIP. Lung density Histograms of patients with an LIP showed a unimodal distribution with a peak at 7 Hounsfield units (HU). Lung density Histograms of patients without an LIP had a bimodal distribution, with a first peak at -727 HU and a second peak at 27 HU. Total respiratory system and lung compliances were lower in patients with an LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without an LIP. The amount of lung overdistension was related to the volume of lung parenchyma, characterized by a CT number less than -800 HU before PEEP implementation (y = 0.52x + 4, R = 0.87, and p < 0.0001). This study shows that the presence or the absence of an LIP on the lung P-V curve is associated with differences in lung morphology. In patients without an LIP on the lung P-V curve, normally aerated lung areas coexist with nonaerated lung areas and increasing levels of PEEP result in lung overdistension rather than in additional alveolar recruitment. In patients with an LIP, air and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolar recruitment without lung overdistention.

Joachim Roschke - One of the best experts on this subject based on the ideXlab platform.

  • is the nonrem rem sleep cycle reset by forced awakenings from rem sleep
    Physiology & Behavior, 2002
    Co-Authors: Michael Grozinger, Domien G M Beersma, Jurgen Fell, Joachim Roschke
    Abstract:

    In selective REM sleep deprivation (SRSD), the occurrence of stage REM is repeatedly interrupted by short awakenings. Typically, the interventions aggregate in clusters resembling the REM episodes in undisturbed sleep. This salient phenomenon can easily be explained if the nonREM-REM sleep process is continued during the periods of forced wakefulness. However, earlier studies have alternatively suggested that awakenings from sleep might rather discontinue and reset the ultradian process. Theoretically, the two explanations predict a different distribution of REM episode duration. We evaluated 117 SRSD treatment nights recorded from 14 depressive inpatients receiving low dosages of Trimipramine. The alarms were triggered by an automatic mechanism for the detection of REM sleep and had to be canceled by the subjects themselves. The REM episodes were determined as in undisturbed sleep-they had to include the remaining REM activity and were separated by 30 min without REM epochs. The Frequency Histogram of REM episodes declined exponentially with episode duration for each of the first four sleep cycles. The duration of nonREM intervals revealed bimodal distributions. These results were found consistent with the model assuming a reset of the ultradian cycle upon awakening. Whether REM or nonREM activity is resumed on return to sleep can be modeled by a random decision whereby the probability for REM sleep might depend on the momentary REM pressure.

Philippe Cluzel - One of the best experts on this subject based on the ideXlab platform.

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Qin Lu, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure–volume (P–V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas–tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 ± 22% versus 55  ± 12%, p < 0.05) and the percentage of poor...

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure-volume (P-V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas-tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 +/- 22% versus 55 +/- 12%, p < 0.05) and the percentage of poorly aerated lung was greater (40 +/- 12% versus 23 +/- 8%, p < 0.05) in patients with an LIP than in patients without an LIP. Lung density Histograms of patients with an LIP showed a unimodal distribution with a peak at 7 Hounsfield units (HU). Lung density Histograms of patients without an LIP had a bimodal distribution, with a first peak at -727 HU and a second peak at 27 HU. Total respiratory system and lung compliances were lower in patients with an LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without an LIP. The amount of lung overdistension was related to the volume of lung parenchyma, characterized by a CT number less than -800 HU before PEEP implementation (y = 0.52x + 4, R = 0.87, and p < 0.0001). This study shows that the presence or the absence of an LIP on the lung P-V curve is associated with differences in lung morphology. In patients without an LIP on the lung P-V curve, normally aerated lung areas coexist with nonaerated lung areas and increasing levels of PEEP result in lung overdistension rather than in additional alveolar recruitment. In patients with an LIP, air and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolar recruitment without lung overdistention.

Louis Puybasset - One of the best experts on this subject based on the ideXlab platform.

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Qin Lu, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure–volume (P–V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas–tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 ± 22% versus 55  ± 12%, p < 0.05) and the percentage of poor...

  • a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung pressure volume curve
    American Journal of Respiratory and Critical Care Medicine, 1999
    Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Jack Richecoeur, Philippe Cluzel, P Coriat, J J Rouby
    Abstract:

    The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung pressure-volume (P-V) curve and to compare the effects of positive end-expiratory pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The volumes of air and tissue within the lungs were measured from the gas-tissue ratio and the volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the Frequency Histogram distribution. In the ZEEP condition, although total lung volume, volume of gas, and volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 +/- 22% versus 55 +/- 12%, p < 0.05) and the percentage of poorly aerated lung was greater (40 +/- 12% versus 23 +/- 8%, p < 0.05) in patients with an LIP than in patients without an LIP. Lung density Histograms of patients with an LIP showed a unimodal distribution with a peak at 7 Hounsfield units (HU). Lung density Histograms of patients without an LIP had a bimodal distribution, with a first peak at -727 HU and a second peak at 27 HU. Total respiratory system and lung compliances were lower in patients with an LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without an LIP. The amount of lung overdistension was related to the volume of lung parenchyma, characterized by a CT number less than -800 HU before PEEP implementation (y = 0.52x + 4, R = 0.87, and p < 0.0001). This study shows that the presence or the absence of an LIP on the lung P-V curve is associated with differences in lung morphology. In patients without an LIP on the lung P-V curve, normally aerated lung areas coexist with nonaerated lung areas and increasing levels of PEEP result in lung overdistension rather than in additional alveolar recruitment. In patients with an LIP, air and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolar recruitment without lung overdistention.