Pressure-Volume Curve of Total Respiratory System in Acute Respiratory Failure: Computed Tomographic Scan Study

Gattinoni, Luciano; Pesenti, Antonio; Avalli, Leonello; Rossi, F; Bombino, Michela

doi:10.1164/ajrccm/136.3.730

Cited by 802 publications

(487 citation statements)

References 6 publications

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“…However, several studies have shown evidence of recruitment beyond LIP (21,23,27). The concept of ongoing recruitment throughout lung inflation has also been supported by mathematical models (12), human studies utilizing computer tomography of the chest (8), and animal models (33). Thus controversy already exists over how recruitment is best served by PEEP.…”

Section: Discussionmentioning

confidence: 99%

Transient mechanical benefits of a deep inflation in the injured mouse lung

Allen

Lundblad

Parsons

et al. 2002

Journal of Applied Physiology

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Allen, Gilman, Lennart K. A. Lundblad, Polly Parsons, and Jason H. T. Bates. Transient mechanical benefits of a deep inflation in the injured mouse lung. J Appl Physiol 93: 1709-1715. First published July 12, 2002 10.1152/japplphysiol.00473.2002The lasting effects of a recruitment maneuver (RM) in the injured lung are not well characterized. We speculated that the reduction in respiratory elastance (H) after a deep inflation (DI) is transient in nature and should be sustained longer at higher positive end-expiratory pressure (PEEP). Thirteen ventilated mice were given 2 DIs at various levels of PEEP before and after saline lavage. Forced oscillations were used to measure H periodically over 7 min after the DIs. Time constants ( ) were estimated for the post-DI recovery in H. Values for before lavage (80-115 s) were reduced after lavage (13-30 s) at all levels of PEEP (P ϭ 0.0001). PEEP did not significantly influence before or after lavage. The plateau level and total recovery in H after a DI were significantly influenced by PEEP and lavage (P Ͻ 0.0001). Our results suggest that for a DI to be beneficial in the injured mouse lung, it may have to be applied several times a minute. atelectasis; acute lung injury; recruitment; elastance; positive-pressure respiration PHYSICIANS HAVE KNOWN for a long time that atelectasis plays a pivotal role in the development of hypoxemia during mechanical ventilation, both in general anesthesia for routine surgery and in various instances of acute lung injury. Recent practice has now moved toward the use of lower tidal volumes (VT) in patients with acute lung injury and acute respiratory distress syndrome (ARDS) after two important studies demonstrated lower mortality outcomes by using this strategy (1, 1a). However, because of the progressive alveolar derecruitment that is often encountered with the use of lower VT (27), there has been a renewed interest in the use of recruitment maneuvers (RMs) as a means of reopening these regions of atelectasis. Many studies have demonstrated improvement in oxygenation, respiratory system compliance, and even lung volume after sustained or deep inflations (DIs) in many different scenarios (3-5, 17, 18, 26, 28), but some of these same studies were unable to show any lasting improvement when RMs were delivered during conventional positive pressure ventilation (4,18,25).These apparently conflicting results may be explained by the different experimental situations involved, as the effect of a RM is likely to depend on the size and duration of the inflation, the mode of ventilation in which the inflation is delivered, and the level of positive end-expiratory pressure (PEEP) employed. Furthermore, if the effects of a RM are transient, then its apparent benefits will depend on when they are measured. Different researchers have measured the effects of a RM at different time points after its administration (3,4,17,26,28), yet there has been little attempt to characterize the rate at which the benefits of a RM are lost in the period immediately after ...

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Section: Discussionmentioning

confidence: 99%

Transient mechanical benefits of a deep inflation in the injured mouse lung

Allen

Lundblad

Parsons

et al. 2002

Journal of Applied Physiology

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“…In fact, the pathological findings of PCP in AIDS patients include interstitial infiltrates associated with alveolar occupation by eosinophilic exudates, hyaline membranes, macrophages, and cellular debris, which oppose recruitment, whilst oedema is moderate or absent [8,9]. Moreover, computed tomography scan performed in eight of our patients exhibited homogeneous diffuse interstitial and alveolar infiltration, at variance with what appears to be the most common finding in ARDS patients in whom dense opacities are mainly confined to the dependent lung regions [27]. Because the presence of an inflection point is taken to indicate alveolar recruitment, the present findings suggest that in AIDS patients with ARDS and PCP there is no substantial alveolar recruitment during lung inflation.…”

Section: Static Inflation V-p Curvementioning

confidence: 50%

“…1 and 2). According to some authors [25][26][27], in ARDS patients without AIDS and PCP the inflection point is a common occurrence, though this might not be particularly frequent according to other studies [22,[28][29][30]. It has been suggested that the inflection is present in the earliest stage of ARDS, whereas later on, probably as a result of oedema resolution, the inflection disappears with or without increases or decreases in elastance, probably depending on the pattern of fibrosis development [26].…”

Section: Static Inflation V-p Curvementioning

confidence: 99%

Lung and chest wall mechanics in patients with acquired immunodeficiency syndrome and severe Pneumocystis carinii pneumonia

et al. 1997

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Lung and chest wall mechanics in patients with acquired immunodeficiency syndrome and severe Pneumocystis carinii pneumonia. E. D 'Angelo, E. Calderini, F.M. Robatto, P. Puccio, J. Milic-Emili. ERS Journals Ltd 1997. ABSTRACT: The aim of this study was to assess the mechanical characteristics of the respiratory system in patients with acquired immune deficiency syndrome (AIDS) and acute respiratory distress syndrome (ARDS) caused by Pneumocystis carinii pneumonia (PCP).In 12 mechanically ventilated patients, total respiratory system mechanics was assessed using the technique of rapid airway occlusion during constant flow inflation, and was partitioned into lung and chest wall components using the oesophageal balloon technique. We measured interrupter resistance (Rint), which mainly reflects airway resistance, additional resistance (∆R) due to viscoelastic behaviour and time constant inequalities, and static elastance (Est). In addition, the static inflation volume-pressure (V-P) curve was assessed. In eight patients, computed tomography scans were performed within 2 days of the assessment of respiratory mechanics.Compared to values reported in the literature for normal subjects, Est and ∆R were markedly increased in AIDS patients with PCP, whilst Rint exhibited a relatively smaller increase. These changes, which involved only the lung and airways, were mainly due to the reduction of ventilated lung units, but additional factors were involved to cause independent modifications of lung stiffness, airway calibre, and viscoelastic properties. The changes in Rint, ∆R, and Est were similar to those observed in other studies on patients with ARDS of different aetiologies. At variance with common observations in the latter patients, none of the AIDS patients with PCP exhibited an inflection point on the static inflation V-P curve, suggesting little or no alveolar recruitment during lung inflation. This finding could be related to the distinctive histopathology of Pneumocystis carinii pneumonia. Indeed, computed tomography revealed homogeneous diffuse interstitial and alveolar infiltration rather than the dense, dependent opacities observed in other studies on acute respiratory distress syndrome of different aetiologies. Eur Respir J 1997; 10: 2343-2350 Pneumocystis carinii pneumonia (PCP) is the most frequent severe opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). It is held responsible for up to 85% of episodes of acute respiratory failure that occur in AIDS [1] and 80% of emergency admissions to intensive care units [2,3], with a reported mortality rate of 75-100% for patients requiring mechanical ventilation [4]. In a recent consensus conference [5], PCP was included, though not by unanimous decision, among the causes of acute respiratory distress syndrome (ARDS), once the following criteria are met: acute onset; arterial oxygen tension (Pa,O 2 )/inspiratory oxygen fraction (FI,O 2 ) <27 kPa (200 mmHg); bilateral infiltrates on chest radiographs; and no evidence of left atrial hyp...

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“…To eliminate the CO 2 , the lungs must be ventilated. As in ARDS, the "baby lung" [4,5] may be extremely small, and each tidal volume entering the baby lung will dilute the CO 2 to a far greater extent than with a normal FRC. The expired end-tidal CO 2 will be proportionally lower and measured as increased alveolar dead space.…”

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confidence: 99%