Smoke Inhalation In Sheep Research Articles

Effects of nebulized adipose-derived mesenchymal stem cells on acute lung injury following smoke inhalation in sheep

IntroductionTreatment of ARDS caused by smoke inhalation is challenging with no specific therapies available. The aim of this study was to test the efficacy of nebulized adipose-derived mesenchymal stem cells (ASCs) in a well-characterized, clinically relevant ovine model of smoke inhalation injury. Material and MethodsFourteen female Merino sheep were surgically instrumented 5–7 days prior to study. After induction of acute lung injury (ALI) by cooled cotton smoke insufflation into the lungs (under anesthesia and analgesia), sheep were placed on a mechanical ventilator for 48 hrs and monitored for cardiopulmonary hemodynamics in a conscious state. ASCs were isolated from ovine adipose tissue. Sheep were randomly allocated to two groups after smoke injury: 1) ASCs group (n = 6): 10 million ASCs were nebulized into the airway at 1 hr post-injury; and 2) Control group (n = 8): Nebulized with saline into the airways at 1 hr post-injury. ASCs were labeled with green fluorescent protein (GFP) to trace cells within the lung. ASCs viability was determined in bronchoalveolar lavage fluid (BALF). ResultsPaO2/FiO2 in the ASCs group was significantly higher than in the control group (p = 0.001) at 24 hrs. Oxygenation index: (mean airway pressure × FiO2/PaO2) was significantly lower in the ASCs group at 36 hr (p = 0.003). Pulmonary shunt fraction tended to be lower in the ASCs group as compared to the control group. GFP-labelled ASCs were found on the surface of trachea epithelium 48 hrs after injury. The viability of ASCs in BALF was significantly lower than those exposed to the control vehicle solution. ConclusionNebulized ASCs moderately improved pulmonary function and delayed the onset of ARDS.

Cutaneous burn diminishes beneficial effect of intravenously administered mesenchymal stem cells on acute lung injury induced by smoke inhalation in sheep

ObjectiveTo investigate effects of intravenously administered allogeneic mesenchymal stem cells (MSCs) on burn/smoke-induced lung injury. MethodsSheep were subjected to 40%, third-degree flame skin burn and smoke inhalation under deep anesthesia and analgesia. One-hour after injury, PlasmaLite A (control) or 200 million MSCs (treatment) were intravenously administered. Pulmonary oxygenation index, PaO2/FiO2 ratio, lung–lymph flow, and bloodless lung wet-to-dry weight ratio were measured. Distribution of MSCs and stromal cell-derived factor-1 (Sdf-1) protein level were determined in lung and skin tissues. Effects of burn exudate on MSCs migration were characterized. ResultsMSCs did not attenuate pulmonary dysfunction. The number of MSCs was significantly higher in lungs of sheep with smoke inhalation compared with those with burn/smoke injury. In contrast, number of MSCs was significantly higher beneath burned skin in sheep with burn/smoke than in unburned skin of sheep with smoke inhalation only. Expression of Sdf-1 protein was increased in the burned skin compared to unburned skin. Effects of burn exudate on cultured MSCs proliferation differed depending on collection time. ConclusionSkin burn diminishes beneficial effects of MSCs on smoke-induced lung injury, by promoting migration of MSCs from the pulmonary tissue to the injured skin area, possibly via expression of Sdf-1 protein.

Effect of ablated bronchial blood flow on survival rate and pulmonary function after burn and smoke inhalation in sheep

The bronchial circulation plays a significant role in the pathophysiological changes of burn and smoke-inhalation injury. Bronchial blood flow markedly increases immediately after inhalational injury. This study examines whether the ablation of the bronchial artery attenuates pathophysiological changes and improves survival after burn and smoke-inhalational injury in an ovine model. Acute lung injury was induced by 40% total body surface-area third-degree cutaneous burn and cotton smoke inhalation (48 breaths of cotton smoke, <40 degrees C) under deep anaesthesia. Twelve adult female sheep were divided into two groups: (1) sham (injured, non-ablated bronchial artery, n=6); (2) ablation (injured, ablated bronchial artery, n=6). Ablation of the bronchial artery was performed 72 h before the injury. The experiment was continued for 96 h. Burn and smoke-inhalation injury significantly increased regional blood flow in the bronchi. Ablation of the bronchial artery significantly reduced acute regional blood flow increases in the proximal and distal bronchi. All animals in the ablation group survived to 96 h. Four of these were successfully weaned off the ventilator. Three animals of the sham group met standardised euthanasia criteria at 60 h, while another met the criteria at 78 h. The lung wet-to-dry weight ratio, histology score and myeloperoxidase (MPO) activity were significantly increased by the insult, but ablation of the bronchial artery attenuated these changes. Burn and smoke-inhalation injury induced a significant increase in bronchial blood flow and accelerated airway obstruction, pulmonary vascular changes, pulmonary oedema and pulmonary dysfunction. Ablated bronchial circulation attenuated these pathophysiological changes.

The complex role of fibrin in acute lung injury

in the last decade there have been many advances in our understanding of the pathogenesis of acute lung injury (ALI), but there have been frustratingly few successful therapeutic interventions. In fact, the only treatment proven to reduce mortality is low tidal volume lung-protective mechanical

Effect of ablated airway blood flow on systemic and pulmonary microvascular permeability after smoke inhalation in sheep

The bronchial circulation plays a significant role in the pathogenesis of smoke inhalation. We investigated the physiological manifestations in both the systemic and the pulmonary circulation after smoke inhalation injury, and determined whether ablation of the bronchial circulation had any effect on these changes. We used a chronically instrumented ovine model with lung and prefemoral lymph fistulae to determine the changes in pulmonary and systemic microvascular permeability. Fourteen animals were divided into two groups. The injection group had bronchial circulation ablation with an ethanol injection into the bronchial artery, whereas it was left intact in the sham group. The sham group showed a four-fold increase in lung lymph flow (l- Q L) and a two-fold increase in prefemoral lymph flow (s- Q L) 24 h after injury. The increase in s- Q L was associated with a decrease in lymph oncotic pressure. Therefore, systemic colloid clearance (s-CC), an indicator of systemic microvascular permeability to protein, was unchanged. The ablated bronchial circulation reversed the pulmonary but not the systemic manifestations after smoke inhalation. In conclusion, the pathophysiological events occurring after smoke inhalation were confined to the lung with increased bronchial blood flow delivering inflammatory mediators directly to the lung parenchyma.

Heparin Nebulization with Recombinant Human Antithrombin Supplementation Improves Pulmonary Gas Exchange in Sepsis Following Smoke Inhalation in Sheep

Heparin Nebulization with Recombinant Human Antithrombin Supplementation Improves Pulmonary Gas Exchange in Sepsis Following Smoke Inhalation in Sheep

General session VI Moderated by Nobutoshi Andou: Lung Vitamin E Depletion Resulting from Burn and Smoke Inhalation in Sheep

Introduction: Oxidants are involved in the pathogenesis of multiple trauma caused by burn and smoke inhalation. α‐ and γ‐tocopherol are major tissue antioxidants and their depletion reflects oxidant injury. We hypothesized that lung vitamin E levels in sheep would be depleted with multiple trauma.Methods: Sheep (n = 31) were surgically prepared for chronic study, then received either a 40% body surface area third‐degree burn, 48 breaths of cotton smoke, a combination of these injuries (B&amp;S) or were given sham injuries. All sheep were resuscitated with Ringer's lactate solution (4 ml/kg/%BSA burn) and mechanically ventilated. The sheep were sacrificed at various time intervals as indicated and vitamin E was measured (nmol/g) in snap‐frozen lung samples obtained at autopsy 48 h postinjury.Results: Lungα‐tocopherol was significantly depressed in sheep with the combination injury, smoke alone and burn alone, respectively, compared to sham treated (p &lt; 0.05). Lungγ‐tocopherol was significantly depressed in sheep with the combination injury compared to sham treated (p &lt; 0.05). Neither smoke alone nor burn alone animals were statistically different from sham.Conclusion: α‐tocopherol depletion may be a result of lipid peroxidation, while γ‐tocopherol depletion may reflect both lipid peroxidation and peroxynitrite damage (nitro‐γ‐tocopherol formation). These results suggest that animals receiving a combination burn and inhalation injury have undergone marked oxidative stress.

Cepharanthin, an alkaloid from Stephania cepharantha, inhibits increased pulmonary vascular permeability in an ovine model of sepsis.

Sepsis is a life-threatening event when it occurs in patients suffering from smoke inhalation injury. Pneumonia is one of the most frequent sources of infection in sepsis. Activated leukocytes likely play a role in the pathogenesis of sepsis. Cepharanthin is a biscoclaurine alkaloid that reportedly inhibits the activation of neutrophils. In this study, we investigated the effects of cephranthin on a post-smoke inhalation model of sepsis in sheep. Female sheep (n = 15) were surgically prepared for the study. After 5 days recovery from the operative procedures, tracheostomy was performed in all animals and 48 breaths of cotton smoke (<40 degrees C) were given via a modified bee smoker under halothane anesthesia. After smoke insufflation, Pseudomonas aeruginosa (5 x 109 cfu/kg) was instilled into the airway using a bronchoscope. All of the animals were mechanically ventilated with 100% O(2). Cepharanthin (1.3 mg/kg/h) was infused in five sheep continuously beginning 1 h after the insult and thereafter for the remainder of the 24-h study period. Control animals (n = 6) were treated with 5% dextrose as a vehicle control. Cepharanthin significantly attenuated changes in lung histology as well as in lung wet/dry weight ratio. An in vitro study revealed that cepharanthin inhibited the release of neutrophil elastase from isolated neutrophils stimulated with either formyl-methyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate with an IC(50) of 60 microM. Cepharanthin also inhibited the fMLP-induced increase in intracellular calcium levels of neutrophils. This result indicates cepharanthin inhibits protein kinase C or a more downstream signaling pathway in neutrophil activation. In conclusion, cepharanthin attenuates acute lung injury and septic shock after smoke inhalation in sheep.

High-dose heparin fails to improve acute lung injury following smoke inhalation in sheep

Thrombin is involved in various inflammatory responses. In sepsis, coagulation abnormalities are major complications. Acute lung injury is one of the most life-threatening problems that can result from sepsis. We hypothesized that high-dose heparin might be effective in attenuating acute lung injury in our sepsis model. Female sheep ( n =16) were surgically prepared for the study. After a tracheotomy, 48 breaths of cotton smoke (<40 degrees C) were insufflated into the airway. Afterwards, live Pseudomonas aeruginosa (5 x 10(11) colony-forming units) bacteria were instilled into the lung. All sheep were ventilated mechanically with 100% O(2), and were divided into three groups: a heparin infusion group ( n =6), a Ringer's lactate infusion group ( n =6), and a sham-injury group ( n =4; surgically prepared in the same fashion but receiving no inhalation injury or bacteria). The treatment was started 1 h after the insult, and was continued thereafter for 24 h. The dose of heparin was adjusted by monitoring to target an activated clotting time of between 300 and 400 s (baseline=approx. 150 s). Sheep exposed to lung injury presented with typical hyperdynamic cardiovascular changes, including an increased cardiac output and a fall in systemic vascular resistance. There was a decrease in the arterial partial pressure of O(2). In conclusion, high-dose heparin did not prevent lung dysfunction in this model, in which acute lung injury was induced by combined smoke and septic challenge.

High-dose heparin fails to improve acute lung injury following smoke inhalation in sheep

Thrombin is involved in various inflammatory responses. In sepsis, coagulation abnormalities are major complications. Acute lung injury is one of the most life-threatening problems that can result from sepsis. We hypothesized that high-dose heparin might be effective in attenuating acute lung injury in our sepsis model. Female sheep (n = 16) were surgically prepared for the study. After a tracheotomy, 48 breaths of cotton smoke (&lt;40°C) were insufflated into the airway. Afterwards, live Pseudomonas aeruginosa (5×1011 colony-forming units) bacteria were instilled into the lung. All sheep were ventilated mechanically with 100% O2, and were divided into three groups: a heparin infusion group (n = 6), a Ringer's lactate infusion group (n = 6), and a sham-injury group (n = 4; surgically prepared in the same fashion but receiving no inhalation injury or bacteria). The treatment was started 1h after the insult, and was continued thereafter for 24h. The dose of heparin was adjusted by monitoring to target an activated clotting time of between 300 and 400s (baseline = approx. 150s). Sheep exposed to lung injury presented with typical hyperdynamic cardiovascular changes, including an increased cardiac output and a fall in systemic vascular resistance. There was a decrease in the arterial partial pressure of O2. In conclusion, high-dose heparin did not prevent lung dysfunction in this model, in which acute lung injury was induced by combined smoke and septic challenge.

Heparin nebulization attenuates acute lung injury in sepsis following smoke inhalation in sheep.

Pseudomonas pneumonia is a common complication of smoke inhalation injury. Airway casts formed from clotted mucous occur frequently in this condition. A recent report shows that intravenous heparin improves oxygenation and reduces lung damage in a sheep model of smoke inhalation. We hypothesized that nebulized heparin could be an effective means of reducing cast formation. Female sheep (n = 19) were surgically prepared for a study of acute lung injury (ALI). After a tracheotomy, 48 breaths of cotton smoke (<40 degrees C) were inflated into the airway. Afterwards, live Pseudomonas aeruginosa (5 x 10(11) CFU) was instilled into the lung. All sheep were mechanically ventilated with 100% O2 and were divided into four groups: a heparin-nebulized group (n = 5; animals received aerosolized heparin [10,000 I.U.] 1 h after the bacterial instillation and subsequently every 4 h thereafter), an intravenous heparin group (n = 5,300 U/kg/23 h, infusion was started 1 h after the injury), a saline-nebulization group (n = 5; animals received inhaled nebulized saline), and a sham injury group (n = 4, treated in the same fashion, but no injury). The animals were sacrificed after 24 h of mechanical ventilation, and lung samples were harvested. Sheep exposed to lung injury presented with typical hyperdynamic cardiovascular changes and a corresponding drop in PaO2. These changes were significantly attenuated in the heparin groups. Histological changes consisting of cellular infiltrates, lung edema, congestion, and cast formation were reduced by heparin. These data suggest that nebulized inhaled heparin is a beneficial therapy for sepsis-induced ALI.

Role of Nitric Oxide Synthase (NOS)-1 and 2 in Acute Lung Injury in Sepsis with Smoke Inhalation in Sheep

Role of Nitric Oxide Synthase (NOS)-1 and 2 in Acute Lung Injury in Sepsis with Smoke Inhalation in Sheep

The Levels of Plasma Vitamin E Depletion Resulting from Burn and Smoke Inhalation in Sheep

The Levels of Plasma Vitamin E Depletion Resulting from Burn and Smoke Inhalation in Sheep

Heparin nebulization attenuates acute lung injury with sepsis after smoke inhalation in sheep

Fibrin formation in the airway is a common occurrence with acute lung injury. Mucous plugging in the airway prevents alveoli expansion and may increase shunt blood flow. The aim of this study was to investigate the effect of heparin nebulization in acute lung injury (ALI) with sepsis or burn after smoke inhalation in sheep.

Novel animal model of septic shock following smoke inhalation

Abstract Background The lesions of smoke inhalation often progress in the context of sepsis and other complications of the burn illness to a critical state consistent with acute respiratory distress syndrome (ARDS). The aim of this study was to develop a standardized and reproducible model of sepsis after smoke inhalation in sheep. Methods Merino ewes (n = 21) were surgically prepared for the study. Five to seven days later, animals received a tracheostomy and 48 breaths of cotton smoke. Pseudomonas aeruginosa was suspended in 30 ml saline, which contained 2–5 × 1011 colony-forming units, and injected into the right lobe (20 ml) and into the left lobe (10 ml) using a bronchoscope. After the bacterial challenge, the animals were ventilated mechanically with 100 per cent oxygen. Body temperature, haemodynamic parameters, blood gas and blood culture were monitored for 48 h. Results The sheep showed a hyperkinetic response and fall in arterial partial pressure of oxygen similar to that seen in severe sepsis in humans. These changes were more severe than in animals with smoke inhalation alone (Fig. 1). Conclusion This would be a good animal model of sepsis and ARDS.

A Novel Animal Model of Sepsis after Smoke Inhalation in Sheep

A Novel Animal Model of Sepsis after Smoke Inhalation in Sheep

This Month in the Journal

This Month in the Journal

Effect of reduced bronchial circulation on lung fluid flux after smoke inhalation in sheep.

We determined the effect of reduced bronchial blood flow on lung fluid flux through changes in lung lymph flow, lung wet weight-to-dry weight (wet/dry) ratios, and pulmonary microvascular reflection coefficient (sigma). In the first of two surgical procedures, Merino ewes (n = 21) were surgically prepared for chronic study. Five to seven days later, in a second operation, the bronchial artery of the injection group (n = 7) was ligated, and 4 ml of 70% ethanol were injected into the bronchial artery to cause sclerosis of the airway circulation. In the ligation group (n = 7), only the bronchial artery was ligated. In the sham group (n = 7), the bronchial artery was surgically exposed but left intact without ligation or ethanol injection. One day after these operations the animals received a tracheotomy and 48 breaths of cotton smoke. The value of sigma was determined at two points: 24 h before the second surgical procedure and 24 h after smoke inhalation. Lung lymph flow, blood-gas parameters, and hemodynamic data were measured every 4 h after injury. At the end of investigation, samples of lung were taken for determination of blood-free wet/dry ratio. In the sham group, inhalation injury induced a gradual increase in pulmonary vascular resistance and lung lymph flow, which was associated with deterioration of oxygenation. Reduction of the bronchial blood flow attenuated these pathophysiological changes, and the degree of this attenuation was greater in the injection group than in the ligation group. The value of sigma was significantly higher after smoke inhalation in the injection group compared with the sham group (0.77 +/- 0.04 vs. 0.61 +/- 0.03, means +/- SE) at 24 h. The mean wet/dry ratio value of the injection group animals was 30% less than that of the sham group. Our data show that the bronchial circulation contributes to edema formation in the lung occurring after acute lung injury with smoke inhalation.

Unilateral smoke inhalation in sheep: effect on left lung lymph flow with right lung injury.

We previously reported that smoke inhalation to the right lung will result in damage to the air-insufflated left lung. In this study we confirm these findings and determine whether this injury is associated with an elevation in lung lymph flow and pulmonary microvascular permeability to protein as indexed by changes in reflection coefficient. Sheep (n = 12) were surgically prepared by placement of a Swan-Ganz catheter and pneumatic occluders on all pulmonary veins and the left pulmonary artery. The left lung lymphatic was selectively cannulated as shown previously (Y. Kikuchi, H. Nakazawa, and D. Traber. Am. J. Physiol. 269 (Regulatory Integrative Comp. Physiol. 38): R943-R947, 1995). All afferent lymphatics from the right lung were severed, and the right pulmonary ligament was sectioned. The caudal end of the lymph node was sectioned to remove systemic lymph contamination. The sheep were studied in the unanesthetized state 7 days later. To ensure that lymph flow was exclusively from the left lung (QLL), right pulmonary microvascular pressure was increased, a procedure that resulted in little or no change in QLL, as was previously shown. The sheep were then anesthetized, and a Carlens tube was positioned to allow separate ventilation of the right and left lung. The right lungs of five sheep and the left lungs of two sheep were insufflated with cotton smoke. Insufflation of the left lung with cotton smoke produced a fourfold increase in QLL that began 4 h after insult. Insufflation of the right lung with smoke led to a doubling of QLL that began 12 h after insult. Changes in QLL were associated with increased microvascular permeability, as indexed by the reflection coefficient. Control sheep (air insufflated into both lungs, n = 5) showed no change in QLL. Injury to the right lung resulted in damage to the left air-insufflated lung, suggesting a hematogenous mediation of the response.

Thromboxane receptor blockade with BM 13,177 following toxic airway damage by smoke inhalation in sheep

Thromboxane may play an important role in the pathogenesis of smoked mediated injury. We studied this possibility in 13 chronically instrumented sheep, which had the left lung exposed to smoke. BM 13,177, a thromboxane receptor antagonist, was given intravenously to six animals prior to smoke inhalation and during the experimental period. Seven animals received the vehicle. All animals were studied for 24 h under ventilatory support, then killed prior to harvesting lung tissue. Airway peak and plateau pressures in the vehicle-treated animals were elevated by 27% and 25% from baseline at 24 h post smoke inhalation. Concomitantly, the left pulmonary vascular resistance index rose continuously throughout the study period (baseline = 822±58; 24 h = 1819±84 dyn·s·cm −5·m 2). BM 13,177 treatment completely prevented the rise in airway pressure, while the left pulmonary vascular resistance index was significantly attenuated (baseline = 726±79; 24 h = 1470±158 dyn·s·cm −5·m 2) resulting in a significantly higher percentage of cardiac output being delivered to the smoked lung, compared to vehicle-treated animals. Thromboxane receptor blockade did not prevent smoke induced pulmonary edema formation. There was likewise no effect of BM 13,177 on the systemic hemodynamic changes seen following smoke inhalation. There was a decrease in cardiac index and an increase in systemic vascular resistance index in both groups. We conclude that smoke induced changes in airway and pulmonary vascular resistances may be mediated by thromboxanes. However, thromboxanes appear to play no role in the development of pulmonary edema and elevation of systemic vascular resistance following smoke inhalation injury.