Acute respiratory distress syndrome

Lung pathology of natural Babesia rossi infection in dogs

A proportion of Babesia rossi infections in dogs are classified as complicated and one of the most lethal complications is acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Most dogs that die succumb within 24 hours of presentation. The pulmonary pathology caused by B. rossi in dogs has not been described. The aim of this study was to provide a thorough macroscopic, histological and immunohistochemical description of the lung changes seen in dogs naturally infected with B. rossi that succumbed to the infection. Death was invariably accompanied by alveolar oedema. Histopathology showed acute interstitial pneumonia characterised by alveolar oedema and haemorrhages, with increased numbers of mononuclear leucocytes in alveolar walls and lumens. Intra-alveolar polymerised fibrin aggregates were observed in just over half the infected cases. Immunohistochemistry showed increased numbers of MAC387- and CD204-reactive monocyte-macrophages in alveolar walls and lumens, and increased CD3-reactive T-lymphocytes in alveolar walls, compared with controls. These histological features overlap to some extent (but far from perfectly) with the histological pattern of lung injury referred to as the exudative stage of diffuse alveolar damage (DAD) as is quite commonly reported in ALI/ARDS.

Interstitial pneumonia and diffuse alveolar damage in domestic animals

Classification of pneumonia in animals has been controversial, and the most problematic pattern is interstitial pneumonia. This is true from the gross and histologic perspectives, and also from a mechanistic point of view. Multiple infectious and noninfectious diseases are associated with interstitial pneumonia, all of them converging in the release of inflammatory mediators that generate local damage and attract inflammatory cells that inevitably trigger a second wave of damage. Diffuse alveolar damage is one of the more frequently identified histologic types of interstitial pneumonia and involves injury to alveolar epithelial and/or endothelial cells, with 3 distinct stages. The first is the “exudative” stage, with alveolar edema and hyaline membranes. The second is the “proliferative” stage, with hyperplasia and reactive atypia of type II pneumocytes, infiltration of lymphocytes, plasma cells, and macrophages in the interstitium and early proliferation of fibroblasts. These stages are reversible and often nonfatal. If damage persists, there is a third “fibrosing” stage, characterized by fibrosis of the interstitium due to proliferation of fibroblasts/myofibroblasts, persistence of type II pneumocytes, segments of squamous metaplasia of alveolar epithelium, plus inflammation. Understanding the lesion patterns associated with interstitial pneumonias, their causes, and the underlying mechanisms aid in accurate diagnosis that involves an interdisciplinary collaborative approach involving pathologists, clinicians, and radiologists.

EphA2 antagonism alleviates LPS-induced acute lung injury via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways

Eph receptor tyrosine kinases have a wide range of biological functions and have gradually been recognized increasingly as key regulators of inflammation and injury diseases. Although previous studies suggested that EphA2 receptor may be involved in the regulation of inflammation and vascular permeability in injured lung, the detailed effects of EphA2 on LPS-induced acute lung injury (ALI) are still inadequate and the underlying mechanism remains poorly understood. In this study, we detected the effects of EphA2 antagonism on inflammation, pulmonary vascular permeability and oxidative stress in LPS-induced ALI and investigate the potential mechanism. Our results showed that EphA2 antagonism markedly inhibited the cytokines release and inflammatory cells infiltration in BALF, prevented the LPS-induced elevations of MPO activity and MDA level in lung tissues. Our study also found that EphA2 antagonism significantly decreased the wet/dry ratios, reduced the Evans blue albumin extravasation in lung tissues and obviously alleviated the LPS-induced increment of pulmonary vascular permeability. Mechanistically, EphA2 antagonism significantly increased the activation of Nrf2 along with its target antioxidant enzyme HO-1 and inhibited the expressions of TLR4/MyD88 in lung tissues and A549 alveolar epithelial cells. Furthermore, EphA2 antagonism dramatically inhibited the LPS-evoked activations of RhoA/ROCK in lung tissues. In conclusion, our data indicate that EphA2 receptor plays an essential role in LPS-induced ALI and EphA2 antagonism has protective effects against LPS-induced ALI via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways. These results suggest that antagonism of EphA2 may be an effective therapeutic strategy for the treatment of ALI.

The alleviative effects of metformin for lipopolysaccharide-induced acute lung injury rat model and its underlying mechanism

For patients who have sepsis, acute lung injury (ALI) causes most of death. Metformin (Met) is an anti-hyperglycemic agent and it has extensive pharmacological properties. This study aimed to analyze the influence of Met on lipopolysaccharide (LPS) -induced ALI. Met (1, 2, and 4 mg/kg) were injected and LPS was injected 30 min later. The data suggested Met can reduce release of inflammatory cytokines and bronchoalveolar lavage fluid (BALF) protein expression, reduce lung wet/dry ratio, and significantly improve LPS-induced lung destruction during ALI. In addition, Met inhibits LPS-induced neutrophil and macrophage infiltration, reduces MPO activity, and promotes AMPK-α1 expression in lung tissues. Our data suggested that metformin alleviates capillary injury during ALI via AMPK-α1.

Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals

OBJECTIVE

To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (FIO2) and other arterial blood gas variables in healthy neonatal foals.

ANIMALS

9 healthy neonatal (3- to 4-day-old) foals.

PROCEDURES

In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal FIO2, intratracheal end-tidal partial pressure of carbon dioxide, and arterial blood gas variables were measured before (baseline) and during unilateral and bilateral nasopharyngeal delivery of 50, 100, 150, and 200 mL of oxygen/kg/min.

RESULTS

No adverse reactions were associated with administration of supplemental oxygen except at the highest flow rate, at which the foals became agitated. At individual flow rates, significant and dose-dependent increases in FIO2, PaO2, and oxygen saturation of hemoglobin (SaO2) were detected, compared with baseline values. Comparison of unilateral and bilateral delivery of oxygen at similar cumulative flow rates revealed no differences in evaluated variables.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that administration of supplemental oxygen via nasal cannulae appeared to be a highly effective means of increasing FIO2, PaO2, and SaO2 in neonatal foals. These findings may provide guidance for implementation of oxygen treatment in hypoxemic neonatal foals.

Acute lung injury/acute respiratory distress syndrome in 15 foals

REASONS FOR PERFORMING STUDY

Few reports exist in the veterinary medical literature describing clinical and pathological findings resembling conditions described as (ALI) and acute respiratory distress syndrome (ARDS) in man.

OBJECTIVES

To document history, clinical, laboratory and diagnostic findings, treatment and outcome of foals age 1-12 months diagnosed with ALI/ARDS at a referral hospital.

METHODS

Medical records, including radiographic, cytological, microbiological, serological and post mortem findings, were reviewed in a retrospective manner to identify foals with acute onset of respiratory distress, a partial pressure of arterial oxygen (PaO2) to fraction of oxygen in inspired gases (FiO2) ratio of < or = 300 mmHg, pulmonary infiltrates on thoracic radiographs or post mortem findings consistent with ALI/ARDS.

RESULTS

Fifteen foals age 1.5-8 months were included in the study. Seven foals had previously been treated for respiratory disease, and all foals developed acute respiratory distress <48 h prior to presentation. Findings on presentation included tachycardia and tachypnoea in all foals, with fever recorded in 8 cases. Eight cases met the criteria for ALI and 7 for ARDS. Radiographic findings demonstrated diffuse bronchointerstitial pattern with focal to coalescing alveolar radiopacities. An aetiological agent was identified in foals ante mortem (n = 6) and post mortem (n = 4). All foals were treated with intranasal oxygen and antimicrobial drugs; 13 received corticosteroids. Nine patients survived, 4 died due to respiratory failure and 2 were subjected to euthanasia in a moribund state. Follow-up was available for 7 foals; all performed as well as age mates or siblings, and one was racing successfully.

CONCLUSIONS

A condition closely meeting the human criteria for ALI/ARDS exists in foals age 1-12 months and may be identical to previously described acute bronchointerstitial pneumonia in young horses.

POTENTIAL RELEVANCE

ALI/ARDS should be suspected in foals with acute severe respiratory distress and hypoxaemia that is minimally responsive to intranasal oxygen therapy. Treatment with systemic corticosteroids, intranasal oxygen and antimicrobials may be beneficial in foals with clinical signs compatible with ALI/ARDS.

Respiratory disease of the bovine neonate

Respiratory disease is an important problem in bovine neonates. Early detection of clinical disease is challenging. In the newborn calf, mucous membrane color, character and frequency of the respiratory effort, thoracic auscultation, and ability to oxygenate are critical elements of the examination to determine whether or not respiratory disease is present. Within a few days of birth, screening calves for fever, abnormal nasal or ocular discharge, or an inducible cough finds many calves with early respiratory disease. This article describes respiratory conditions in newborn calves that veterinarians are most likely to encounter, along with diagnostic and treatment options that can be applied to both herd investigations and individual animals.

Lidocaine attenuates lipopolysaccharide-induced acute lung injury through inhibiting NF-kappaB activation

BACKGROUND AND OBJECTIVES

Lidocaine has been reported to attenuate the inflammatory response in addition to its anesthetic activity, but the mechanisms are poorly understood. The objective of this study is to determine if lidocaine prior to endotoxemia diminishes pulmonary dysfunction by blocking the NF-kappaB activation.

METHODS

Rats were assigned to: (1) control (0.9% sodium chloride); (2) lipopolysaccharides (LPS); (3) LPS + lidocaine 1 mg/kg; (4) LPS + lidocaine 2 mg/kg, and (5) LPS + lidocaine 4 mg/kg. The LPS and LPS + lidocaine 4 mg/kg groups were subjected to 1-, 3-, 6- and 12-hour time points. To investigate the activation of NF-kappaB, the expression of NF-kappaB in the nuclear and I kappaB alpha in the cytosol extracts were analyzed by Western blot. The concentration of TNF-alpha and IL-6 in serum was detected by ELISA. The pathologic changes of the lung were observed using HE staining.

RESULTS

After i.p. injection of LPS, the expression of NF-kappaB in the nuclear extracts was significantly increased and I kappaB alpha in the cytosol extracts was markedly decreased. The concentration of TNF-alpha and IL-6 in serum was increased. Pathological examination showed that the normal structure of the lung was destroyed badly. However, lidocaine reversed the above results.

CONCLUSION

Lidocaine attenuates LPS-induced lung injury via mechanisms involving inhibiting NF-kappaB activation and cytokine release, which implies that lidocaine may be a potential anti-inflammatory agent in endotoxemia.