Evaluation of respiratory mechanics and lung histology in a model of atelectasis

Contador, Renata S.; Chagas, Paula Silva de Carvalho; Vasconcellos, Fernanda P.; Feijoo, M. Montero; Faffe, Débora S.; Rocco, Patricia R. M.; Zin, Walter A.

doi:10.1016/s1569-9048(03)00125-3

Cited by 4 publications

(5 citation statements)

References 34 publications

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“…These apparent discrepancies could be attributed to the occasional dissociation between lung histology and mechanics. In fact, a threshold of alveolar collapse and collagen fibre content modifications to induce changes in Est,L has been reported [8,27]. In contrast, in vitro lung mechanical changes were usually very well correlated with modifications in the amount of collagen and elastic fibres [8,10].…”

Section: Discussionmentioning

confidence: 99%

Early short-termversusprolonged low-dose methylprednisolone therapy in acute lung injury

Silva¹,

Garcia²,

Maronas³

et al. 2008

Eur Respir J

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The present study compared the effects of early short-term with prolonged low-dose corticosteroid therapy in acute lung injury (ALI).In total, 120 BALB/c mice were randomly divided into five groups. In the control group, saline was intratracheally (i.t.) instilled. In the ALI group, mice received Escherichia coli lipopolysaccharide (10 mg i.t.). ALI animals were further randomised into four subgroups to receive saline (0.1 mL i.v.) or methylprednisolone (2 mg?kg -1 i.v.) at 6 h, 24 h or daily (for 7 days, beginning at day 1). At 1, 3 and 8 weeks, in vivo and in vitro lung mechanics and histology (light and electron microscopy), collagen and elastic fibre content, cytokines in bronchoalveolar lavage fluid and the expression of matrix metalloproteinase (MMP)-9 and -2 were measured. In vivo (static elastance and viscoelastic pressure) and in vitro (tissue elastance and resistance) lung mechanics, alveolar collapse, cell infiltration, collagen and elastic fibre content and the expression of MMP-9 and MMP-2 were increased in ALI at 1 week. Methylprednisolone led to a complete resolution of lung mechanics, avoided fibroelastogenesis and the increase in the expression of MMP-9 and MMP-2 independent of steroid treatment design.Thus, early short-term, low-dose methylprednisolone is as effective as prolonged therapy in acute lung injury.

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Section: Discussionmentioning

confidence: 99%

Early short-termversusprolonged low-dose methylprednisolone therapy in acute lung injury

Silva¹,

Garcia²,

Maronas³

et al. 2008

Eur Respir J

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“…ALI reproducibility was of great importance since lung injury severity as well as ventilation settings could be standardized among all animals, thus avoiding the usual limitations observed in clinical trials. The ATEL model (16) was used to discriminate whether the deleterious effects of RMs were related to the previous degree of atelectasis present in our ALI model (45) or, alternatively, to parenchymal inflammation.…”

Section: Discussionmentioning

confidence: 99%

“…In the CTRL group (n ϭ 19), saline [0.9% NaCl, 5 ml/kg body wt (BW)] was injected intraperitoneally. In the atelectasis group (ATEL) (n ϭ 19), a model of reproducible atelectasis previously developed was used (16). Briefly, atelectasis was generated by a pediatric sphygmomanometer wrapped around the thorax of the animal from the axilla to the subcostal plane.…”

Section: Methodsmentioning

confidence: 99%

“…Briefly, atelectasis was generated by a pediatric sphygmomanometer wrapped around the thorax of the animal from the axilla to the subcostal plane. The cuff was inflated to a transpulmonary pressure of Ϫ8 cmH 2O, which was maintained for 5 s. Then the sphygmomanometer was taken off to allow further measurements (16). In the ALI group (n ϭ 19), paraquat was injected intraperitoneally (10 mg/kg BW) 24 h before the measurements (45).…”

Section: Methodsmentioning

confidence: 99%

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Positive end-expiratory pressure prevents lung mechanical stress caused by recruitment/derecruitment

Farias

Faffe

Xisto

et al. 2005

Journal of Applied Physiology

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This study tests the hypotheses that a recruitment maneuver per se yields and/or intensifies lung mechanical stress. Recruitment maneuver was applied to a model of paraquat-induced acute lung injury (ALI) and to healthy rats with (ATEL) or without (CTRL) previous atelectasis. Recruitment was done by using 40-cmH(2)O continuous positive airway pressure for 40 s. Rats were, then, ventilated for 1 h at zero end-expiratory pressure (ZEEP) or positive end-expiratory pressure (PEEP; 5 cmH(2)O). Atelectasis was generated by inflating a sphygmomanometer around the thorax. Additional groups did not undergo recruitment but were ventilated for 1 h under ZEEP. Lung resistive and viscoelastic pressures and static elastance were computed before and immediately after recruitment, and at the end of 1 h of ventilation. Lungs were prepared for histology. Type III procollagen (PCIII) mRNA expression in lung tissue was analyzed by RT-PCR. Lung mechanics improved after recruitment in the CTRL and ALI groups. One hour of ventilation at ZEEP increased alveolar collapse, static elastance, and lung resistive and viscoelastic pressures. Alveolar collapse was similar in ATEL and ALI, and recruitment opened the alveoli in both groups. ALI showed higher PCIII expression than ATEL or CTRL groups. One hour of ventilation at ZEEP did not increase PCIII expression but augmented it significantly in the three groups when applied after recruitment. However, PEEP ventilation after recruitment avoided any increment in PCIII expression in all groups. In conclusion, recruitment followed by ZEEP was more deleterious in ALI than in mechanical ATEL, although ZEEP alone did not elevate PCIII expression. Ventilation with 5-cmH(2)O PEEP prevented derecruitment and aborted the increase in PCIII expression.

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“…In clinical studies, areas of atelectasis are usually assessed by computer tomography. Histological examination by light microscopy to illustrate alveolar collapse (18), distension, or effects of intervention has been used in animal studies (15). In this study, that method was applied to verify the distribution of suction atelectasis.…”

Section: Introductionmentioning

confidence: 99%

A recruitment breath manoeuvre directly after endotracheal suction improves lung function: An experimental study in pigs

Kasim¹,

Gulyás²,

Almgren

et al. 2009

Upsala Journal of Medical Sciences

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BackgroundAtelectasis occurs after a well performed endotracheal suction. Clinical studies have shown that recruitment manoeuvres added after endotracheal suction during mechanical ventilation restore lung function. Repetitive lung over-distension is, however, harmful for the lung, and the effects of adding a larger breath, recruitment breath, directly after repeated endotracheal suction were therefore investigated.MethodsTwelve healthy anaesthetized pigs were randomized into two groups: one without and one with a recruitment breath manoeuvre (RBM), i.e. a breath 15 cmH2O above inspiratory pressure for 10 s during pressure-controlled ventilation. The pigs were suctioned every hour for 4 hours with an open suction system.ResultsAt the end of the study there was a statistically significant difference between the group given RBM and that without with respect to PaCO2, tidal volume (VT), and compliance (Crs). Without RBM, the PaCO2 increased from 4.6±0.4 to 6.1±1.5 kPa, VT decreased from 345±39 to 247±71 mL, and Crs decreased from 28±6 to 18±5 mL/cmH2O. There was no change in PaCO2 or Crs when a RBM was given. Morphological analysis revealed no differences in aeration of apical and central lung parenchyma. In the basal lung parenchyma there were, however, greater areas with normal lung parenchyma and less atelectasis after RBM.ConclusionsAtelectasis created by endotracheal suction can be opened by inflating the lung for a short duration with low pressure, without over-distension, immediately after suction.

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Evaluation of respiratory mechanics and lung histology in a model of atelectasis

Cited by 4 publications

References 34 publications

Early short-termversusprolonged low-dose methylprednisolone therapy in acute lung injury

Early short-termversusprolonged low-dose methylprednisolone therapy in acute lung injury

Positive end-expiratory pressure prevents lung mechanical stress caused by recruitment/derecruitment

A recruitment breath manoeuvre directly after endotracheal suction improves lung function: An experimental study in pigs

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