Article

Recruitment maneuver in experimental acute lung injury: The role of alveolar collapse and edema

Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Critical care medicine (Impact Factor: 6.31). 11/2010; 38(11):2207-14. DOI: 10.1097/CCM.0b013e3181f3e076
Source: PubMed

ABSTRACT

In acute lung injury, recruitment maneuvers have been used to open collapsed lungs and set positive end-expiratory pressure, but their effectiveness may depend on the degree of lung injury. This study uses a single experimental model with different degrees of lung injury and tests the hypothesis that recruitment maneuvers may have beneficial or deleterious effects depending on the severity of acute lung injury. We speculated that recruitment maneuvers may worsen lung mechanical stress in the presence of alveolar edema.
Prospective, randomized, controlled experimental study.
University research laboratory.
Thirty-six Wistar rats randomly divided into three groups (n = 12 per group).
In the control group, saline was intraperitoneally injected, whereas moderate and severe acute lung injury animals received paraquat intraperitoneally (20 mg/kg [moderate acute lung injury] and 25 mg/kg [severe acute lung injury]). After 24 hrs, animals were further randomized into subgroups (n = 6/each) to be recruited (recruitment maneuvers: 40 cm H₂O continuous positive airway pressure for 40 secs) or not, followed by 1 hr of protective mechanical ventilation (tidal volume, 6 mL/kg; positive end-expiratory pressure, 5 cm H₂O).
Only severe acute lung injury caused alveolar edema. The amounts of alveolar collapse were similar in the acute lung injury groups. Static lung elastance, viscoelastic pressure, hyperinflation, lung, liver, and kidney cell apoptosis, and type 3 procollagen and interleukin-6 mRNA expressions in lung tissue were more elevated in severe acute lung injury than in moderate acute lung injury. After recruitment maneuvers, static lung elastance, viscoelastic pressure, and alveolar collapse were lower in moderate acute lung injury than in severe acute lung injury. Recruitment maneuvers reduced interleukin-6 expression with a minor detachment of the alveolar capillary membrane in moderate acute lung injury. In severe acute lung injury, recruitment maneuvers were associated with hyperinflation, increased apoptosis of lung and kidney, expression of type 3 procollagen, and worsened alveolar capillary injury.
In the presence of alveolar edema, regional mechanical heterogeneities, and hyperinflation, recruitment maneuvers promoted a modest but consistent increase in inflammatory and fibrogenic response, which may have worsened lung function and potentiated alveolar and renal epithelial injury.

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    • "Group 3: designated PQ + HBOT, was injected intraperitoneally daily with PQ at a single dose of 20 mg/kg body weight and was administered 100% O 2 at 2.0 ATA for 1 hour per day, for five consecutive days, three days after PQ treatment. Lung injury was induced by paraquat as previously described[11]. Paraquat dichloride (methyl violgen, Sigma) was dissolved in saline (0.9% NaCl) and animals were given 20 mg/kg intraperitoneal injection in each case. "
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    ABSTRACT: Abstract: Paraquat (PQ) is an agrochemical agent commonly used worldwide, which can cause acute lung injury (ALI) and death. Hyperbaric oxygen treatment (HBOT) is a therapeutic method, but the mechanisms of the protective effect of HBOT on ALI remain elusive. The purpose of this study was to evaluate the effect of HBOT on acute lung injury induced by PQ in rats. Wistar Albino rats (n=21) were separated into three groups of seven animals each: control (C), PQ, and PQ + HBOT groups. 20 mg/kg PQ was administered intraperitoneally in PQ and PQ + HBOT groups to induce experimental lung injury. Three days after PQ treatment, PQ+HBOT group was administered 100% O at 2.0 ATA for 1 hour per day, for five consecutive days. At the end of the study, lung tissue was obtained for determining total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI) and histopathological determination. Tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), transforming growth factor (TGF)-β1 mRNA levels were assessed by quantitative reverse transcription-polymerase chain reaction. In addition, the inducible nitric oxide synthase (iNOS) level in the plasma was determined. Plasma iNOS, OSI, tissue TNF-α, TGF-β1 and bFGF mRNA levels, and histological injury scores in PQ + HBOT group were significantly lower than PQ group. TAS level in PQ + HBOT group was significantly higher than PQ group. The findings suggest that HBOT could effectively ameliorate PQ-induced lung injury in rats. Keywords: Paraquat, lung injury, hyperbaric oxygen treatment, oxidant, antioxidant
    Full-text · Article · Dec 2015 · International journal of clinical and experimental pathology
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    • "The number of points falling on areas of perivascular edema and the number of intercepts between the lines of the integrating eyepiece and the basal membrane of the vessels were counted. The interstitial perivascular edema index was calculated as follows: number of points 1/2 /number of intercepts (Santiago et al., 2010 "
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    ABSTRACT: We evaluated whether the short-term use of dexmedetomidine and propofol may attenuate inflammatory response and improve lung morphofunction in experimental acute lung injury (ALI). Thirty-six Wistar rats were randomly divided into five groups. Control (C) and ALI animals received sterile saline solution and Escherichia coli lipopolysaccharide by intraperitoneal injection respectively. After 24 h, ALI animals were randomly treated with dexmedetomidine, propofol, or thiopental sodium for 1 h. Propofol reduced static lung elastance and resistive pressure and was associated with less alveolar collapse compared to thiopental sodium and dexmedetomidine. Dexmedetomidine improved oxygenation, but did not modify lung mechanics or histology. Propofol was associated with lower IL (interleukin)-6 and IL-1β expression, whereas dexmedetomidine led to reduced inducible nitric oxide (iNOS) and increased nuclear factor erythroid 2-related factor 2 (Nrf2) expression in lung tissue compared to thiopental sodium. In conclusion, in this model of mild ALI, short-term use of dexmedetomidine and propofol led to different functional effects and activation of biological markers associated with pulmonary inflammation.
    Full-text · Article · Nov 2014 · Respiratory Physiology & Neurobiology
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    • "Hyperinflation (HI) is one of the recruitment maneuvers (RM) used to stimulate a cough, recover oxygenation and improve compliance, following OES in mechanically-ventilated subjects (Hodgson et al., 2000; Patman et al., 2000; Berney and Denehy, 2007). Previous studies have demonstrated an association between RM and cytokine release (Talmor et al., 2007) and that RM directly promotes cytokine releases, increases lung stress and compromises lung function (Santiago et al., 2010). If indeed this is the case, the release of inflammatory mediators from the injured lung into the systemic circulation could lead to distal organ failure (Wheeler and Bernard, 2007). "
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    ABSTRACT: Endothelin-1 (ET-1) is a mediator of various physiological and pathological processes, including vascular inflammation, cell proliferation and vasoconstriction. Attenuation of ET action using ET-1 antagonists reduces pulmonary vascular leakage and inflammation in several models of lung injuries and experimental acute respiratory distress syndrome (ARDS). Based on these earlier reports, the current study investigates the patterns of ET-1 levels in circulation and pulmonary tissues in an experimental model of lavage-induced surfactant-depleted lung injury. Additionally, we also test the effects of open endotracheal suctioning (OES) and hyperinflation (HI) as recruitment maneuver following OES on ET-1 levels. Briefly, 24 Japanese white rabbits were anesthetized and intubated. Normal saline was instilled into the lung and washed mildly. After instillation, rabbits were ventilated at definite settings at a total duration of 3hours. OES and HI were performed every 15minutes from the beginning of the protocol. Here, we show that both circulatory and pulmonary ET-1 levels increased in models with lung injury induced by saline lavage compared to healthy control group. No further aggravation in expression of pulmonary ET-1 was seen after OES and HI, although OES and HI worsened arterial hypoxygenation and severity of lung injury. In contrast, circulatory ET-1 levels significantly decreased after OES and HI but were not associated with blood pressure changes. We conclude that in a saline lavage-induced lung injury model, both circulatory and pulmonary ET-1 levels increased. Further, OES and HI exerted differential effects on ET-1 expression at both circulatory and pulmonary levels.
    Full-text · Article · Apr 2014 · Life sciences
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