Effect of raised alveolar pressure on leukocyte retention in the human lung

Hiding in plain sight? A review of post-convulsive leukocyte elevations

During physiological stress responses such as vigorous exercise, emotional states of fear and rage, and asphyxia, the nervous system induces a massive release of systemic catecholamines that prepares the body for survival by increasing cardiac output and redirecting blood flow from non-essential organs into the cardiopulmonary circulation. A curious byproduct of this vital response is a sudden, transient, and redistributive leukocytosis provoked mostly by the resultant shear forces exerted by rapid blood flow on marginated leukocytes. Generalized convulsive seizures, too, result in catecholamine surges accompanied by similar leukocytoses, the magnitude of which appears to be rooted in semiological factors such as convulsive duration and intensity. This manuscript reviews the history, kinetics, physiology, and clinical significance of post-convulsive leukocyte elevations and discusses their clinical utility, including a proposed role in the scientific investigation of sudden unexpected death in epilepsy (SUDEP).

Lung inflammatory response syndrome after cardiac-operations and treatment of lornoxicam

The majority of patients survive after extracorporeal circulation without any clinically apparent deleterious effects. However, disturbances exist in various degrees sometimes, which indicate the harmful effects of cardiopulmonary bypass (CPB) in the body. Several factors during extracorporeal circulation either mechanical dependent (exposure of blood to non-biological area) or mechanical independent (surgical wounds, ischemia and reperfusion, alteration in body temperature, release of endotoxins) have been shown to trigger the inflammatory reaction of the body. The complement activation, the release of cytokines, the leukocyte activation and accumulation as well as the production of several "mediators" such as oxygen free radicals, metabolites of arachidonic acid, platelet activating factors (PAF), nitric acid, and endothelin. The investigation continues today on the three metabolites of lornoxicam (the hydroxylated metabolite and two other metabolites of unknown chemical composition) to search for potential new pharmacological properties and activities.

Effect of lornoxicam in lung inflammatory response syndrome after operations for cardiac surgery with cardiopulmonary bypass

BACKGROUND

The establishment of Extracorporeal Circulation (EC) significantly contributed to improvement of cardiac surgery, but this is accompanied by harmful side-effects. The most important of them is systemic inflammatory response syndrome. Many efforts have been undertaken to minimize this problem but unfortunately without satisfied solution to date.

MATERIALS AND METHODS

Lornoxicam is a non steroid anti-inflammatory drug which temporally inhibits the cycloxygenase. In this clinical trial we study the effect of lornoxicam in lung inflammatory response after operations for cardiac surgery with cardiopulmonary bypass. In our study we conclude 14 volunteers patients with ischemic coronary disease undergoing coronary artery bypass grafting with EC. In seven of them 16 mg lornoxicam was administered iv before the anesthesia induction and before the connection in heart-lung machine. In control group (7 patients) we administered the same amount of normal saline.

RESULTS

Both groups are equal regarding pro-operative and intra-operative parameters. The inflammatory markers were calculated by Elisa method. We measured the levels of cytokines (IL-6, IL-8, TNF-a), adhesion molecules (ICAM-1, e-Selectin, p-Selectin) and matrix metaloproteinase-3 (MMP-3) just after anesthesia induction, before and after cardiopulmonary bypass, just after the patients administration in ICU and after 8 and 24 hrs. In all patients we estimated the lung's inflammatory reaction with lung biopsy taken at the begging and at the end of the operation. We calculated hemodynamics parameters: Cardiac Index (CI), Systemic Vascular Resistance Index (SVRI), Pulmonary Vascular Resistance Index (PVRI), Left Ventricular Stroke Work Index (LVSWI), Right Ventricular Stroke Work Index (RVSWI), and the Pulmonary arterial pressure, and respiratory parameters too: alveolo-arterial oxygen difference D (A-a), intrapulmonary shunt (Qs/Qt) and pulmonary Compliance. IL-6 levels of lornoxicam group were statistical significant lower at 1st postoperative day compared to them of control group (113±49 and 177±20 respectively, P=0.008). ICAM-1 levels were statistical significant lower at the patient admission in ICU, compared to them of control group (177±29 and 217±22 respectively, P=0.014), and the 1st postoperative day compared to them in control group (281±134 and 489±206 respectively, P=0.045). P-selectin levels were statistical significant lower, compared to them in control group in four measurements (97±23 and 119±7 respectively, P=0.030, 77±19 and 101±20 respectively, P=0.044, 86±4 and 105±13 respectively, P=0.06, 116±13 and 158±17 respectively, P=0.000).

CONCLUSIONS

Hemodynamics and respiratory parameters were improved compared to control group, but these differences was not statistical significant. Eosinofil adhesion and sequestration in intermediate tissue of lung parenchyma were significantly lower compared to control group. Also, alveolar edema was not noted in lornoxicam's group. Lornoxicam reduce the inflammatory response in patients undergone coronary artery bypass grafting with extracorporeal circulation. This calculated from levels reduction of IL-6, ICAM-1 και p-Selectin, and from lung pathologoanatomic examination (absence of alveolar edema, reduce in eosinofil adhesion and sequestration in intermediate tissues). Despite the favorable effect of lornoxicam on the hemodinamics and respiratory parameters these improvement did not seem to be statistical significant.

Platelets in lung biology

Platelets and the lungs have an intimate relationship. Platelets are anucleate mammalian blood cells that continuously circulate through pulmonary vessels and that have major effector activities in hemostasis and inflammation. The lungs are reservoirs for megakaryocytes, the requisite precursor cell in thrombopoiesis, which is the intricate process by which platelets are generated. Platelets contribute to basal barrier integrity of the alveolar capillaries, which selectively restricts the transfer of water, proteins, and red blood cells out of the vessels. Platelets also contribute to pulmonary vascular repair. Although platelets bolster hemostatic and inflammatory defense of the healthy lung, experimental evidence and clinical evidence indicate that these blood cells are effectors of injury in a variety of pulmonary disorders and syndromes. Newly discovered biological capacities of platelets are being explored in the context of lung defense, disease, and remodeling.

Does inhalation of ultrafine particles cause pulmonary vascular effects in humans?

Inhalation of ambient particulate matter increases the risk of cardiovascular disease. Clinical studies play an important role in elucidating mechanisms for pollutant effects, and in establishing ambient air quality standards. Ultrafine particles (UFP; diameter <100 nm) may be important in the cardiovascular effects of ambient PM, yet there are few clinical studies of UFP health effects. Our laboratory has developed an exposure facility for clinical studies of laboratory-generated UFP. We confirmed previous predictions that UFP <50 nm in diameter deposit in the respiratory tract with a high efficiency, and have shown that exercise or the presence of asthma further increases UFP deposition. UFP exposure with exercise reduced expression of selected adhesion molecules on blood leukocytes, and also decreased the pulmonary diffusing capacity for carbon monoxide. These findings are best explained by UFP effects on pulmonary vascular function. These findings provide a possible mechanism by which inhalation of UFP may contribute to cardiopulmonary health effects in susceptible people.

Neutrophil cytoskeletal rearrangements during capillary sequestration in bacterial pneumonia in rats

RATIONALE

Neutrophils accumulate in pulmonary capillaries during acute inflammation. Initial events in injury recognition and sequestration do not occur through selectin-mediated rolling. Cytoskeletal rearrangements, as assessed by submembrane F-actin rims, result in poorly deformable neutrophils that may not pass through capillaries.

OBJECTIVE

To test the hypothesis that neutrophils sequestering during pneumonia contain F-actin rims and to determine the roles of CD11/CD18, L-selectin expression, and neutrophil-platelet adhesion in neutrophil sequestration.

METHODS

Neutrophils were compared in blood obtained simultaneously from venous and arterial sites before and 4 h after instillation of Streptococcus pneumoniae or Escherichia coli in rats.

MEASUREMENTS AND MAIN RESULTS

At 4 h of pneumonia, the number of neutrophils was greater in the venous blood entering the lungs than in the arterial blood leaving the lungs, indicating that neutrophil sequestration was occurring. More neutrophils entering the lungs contained F-actin rims than did neutrophils exiting, and the venous-arterial difference in F-actin-rimmed neutrophil counts completely accounted for sequestration. In E. coli pneumonia, in which neutrophil adhesion is mediated by CD11/CD18, CD18 blockade 15 min before blood samples were obtained did not prevent this sequestration of F-actin-rimmed neutrophils. Neutrophils expressing high or low levels of L-selectin or of neutrophils that bound platelets while circulating did not preferentially sequester.

CONCLUSIONS

Neutrophils with cytoskeletal rearrangements preferentially sequester within the lungs during pneumonia, and this sequestration is not due to CD11/CD18-mediated adhesion, L-selectin expression, or platelet adhesion to neutrophils, suggesting that cytoskeletal rearrangements result in sequestration of neutrophils.

Pathophysiology of airflow limitation in chronic obstructive pulmonary disease

The airflow limitation that defines chronic obstructive pulmonary disease (COPD) is the result of a prolonged time constant for lung emptying, caused by increased resistance of the small conducting airways and increased compliance of the lung as a result of emphysematous destruction. These lesions are associated with a chronic innate and adaptive inflammatory immune response of the host to a lifetime exposure to inhaled toxic gases and particles. Processes contributing to obstruction in the small conducting airways include disruption of the epithelial barrier, interference with mucociliary clearance apparatus that results in accumulation of inflammatory mucous exudates in the small airway lumen, infiltration of the airway walls by inflammatory cells, and deposition of connective tissue in the airway wall. This remodelling and repair thickens the airway walls, reduces lumen calibre, and restricts the normal increase in calibre produced by lung inflation. Emphysematous lung destruction is associated with an infiltration of the same type of inflammatory cells found in the airways. The centrilobular pattern of emphysematous destruction is most closely associated with cigarette smoking, and although it is initially focused on respiratory bronchioles, separate lesions coalesce to destroy large volumes of lung tissue. The panacinar pattern of emphysema is characterised by a more even involvement of the acinus and is associated with alpha1 antitrypsin deficiency. The technology needed to diagnose and quantitate the individual small airway and emphysema phenotypes present in people with COPD is being developed, and should prove helpful in the assessment of therapeutic interventions designed to modify the progress of either phenotype.

Multiple organ dysfunction syndrome: a narrative review

PURPOSE

To review multiple organ dysfunction syndrome with respect to: 1) clinical measurement systems; 2) molecular mechanisms; and 3) therapeutic directions based upon molecular mechanisms.

METHODS

The Medline, Cochrane, and Best Evidence databases (1996 to 2000), conference proceedings, bibliographies of review articles were searched for relevant articles. Key index words were multiple organ failure, multiple system organ dysfunction, sepsis, septic shock, shock, systemic inflammatory response syndrome. Outcomes prospectively defined were death and physiological reversal of end organ failure.

RESULTS

Multiple organ dysfunction/failure (MODS) is the most common cause for death in intensive care units. The recognition of this syndrome in the last 30 yr may be due to advances in early resuscitation unmasking these delayed sequelae in those that would have died previously. Multiple organ dysfunction occurs after shock of varied etiologies and may be the result of unbridled systemic inflammation. As yet, therapy directed to prevent or improve MODS has not dramatically altered outcomes.

CONCLUSION

Multiple organ dysfunction may serve as useful measure of disease severity for risk adjustment and outcome marker for quality of care and therapy provided. Anesthesiologists treating shock patients will note the subsequent development of MODS in the critical care unit and may be required to provide anesthetic support to these patients.

Pulmonary blood flow distribution in stage 1 chronic obstructive pulmonary disease

We investigated the hypothesis that lung blood flow distribution is modified in stage 1 chronic obstructive pulmonary disease (COPD). We compared patients with stage 1 COPD (n = 11) with restrictive patients with comparable blood gases (n = 7), to patients with low cardiac index with normal lungs (n = 11) and to control subjects (n = 11). Distribution of transit time (DTT) was computed by deconvolution from first pass radioactivity curves (albumin (99m)Tc) reconstructed from right and left ventricular regions of interest. Distribution descriptors, mean transit time (p < 0.05), standard deviation (p < 0.001), relative dispersion (p < 0.001), and kurtosis (p < 0.001) differed between groups (ANOVA). Cardiac index was the same in COPD and low CI groups but lower compared with normal subjects (p < 0.05). After normalization for cardiac output, the DTT of patients with COPD remained different from low CI and restrictive patients (p < 0.001). Therefore changes in DTT in patients with COPD compared with patients without COPD could not be explained on the basis of difference in cardiac output. Because P(O(2)), PC(O(2)), and pH were similar in COPD and restrictive groups, difference in distribution could not be explained either on the basis of blood gas data. We conclude that changes in DTT occurs in stage 1 COPD and cannot be explained by hypoxemia, hypercapnia, or acidosis alone but must relate to other structural or regulatory responses.

The nonspecific inflammatory response to injury

PURPOSE

The role of the nonspecific inflammatory response in causing injury related to surgery has become better understood over the last decade. There are complex interactions between neutrophils, cytokines and nitric oxide metabolites that may cause organ injury following surgery. The purpose of this review is to summarize some of the processes causing injury through these nonspecific pathways.

METHODS

A review of the medical and anaesthetic literature related to inflammation, neutrophils and pro-inflammatory cytokines were performed using Medline. Bibliographies of relevant articles were searched and additional articles were then selected and reviewed.

RESULTS

Pro-inflammatory cytokines, such as tumour necrosis factor, are released in response to a variety of noxious stimuli (e.g. burns, sepsis, or CABG surgery). These cytokines cause activation of neutrophils with increased upregulation of adhesion complexes on neutrophils and vascular endothelium. Nitric oxide synthase activity is also increased with a resultant increased production of nitric oxide. The increased nitric oxide concentration in the presence of superoxide free radicals secreted by activated neutrophils forms peroxynitrite, a more reactive and toxic molecule. Once this process is initiated, diffuse organ injury can result. Although some information related to specific anaesthetics is available, firm recommendations related to clinical practice cannot be made.

CONCLUSIONS

There is a complex interplay of inflammatory mediators that can cause injury. Although specific clinical applications for manipulating these pathways are not yet generally available, this area holds promise to develop new techniques to improve outcomes following surgery.

Effects of anatomic variability on blood flow and pressure gradients in the pulmonary capillaries

A theoretical model is developed to simulate the flow of blood through the capillary network in a single alveolar septum. The objective is to study the influence of random variability in capillary dimension and compliance on flow patterns and pressures within the network. The capillary bed is represented as an interconnected rectangular grid of capillary segments and junctions; blood flow is produced by applying a pressure gradient across the network. Preferred flow channels are shown to be a natural consequence of random anatomic variability, the effect of which is accentuated at low transcapillary pressures. The distribution of pressure drops across single capillary segments widens with increasing network variability and decreasing capillary transmural pressure. Blockage of one capillary segment causes the pressure drop across that segment to increase by 60%, but the increase falls to < 10% at a distance of three segments. The factors that cause nonuniform capillary blood flow through the capillary network are discussed.

Eosinophilic leukocyte accumulation during vagally induced bronchoconstriction

Eosinophilic leukocytes (eosinophils) are important effector cells in allergic inflammatory diseases such as asthma, in which significant accumulation of these cells is observed in the bronchial mucosa. However, there is little information about the relationships between bronchoconstriction and accumulation of eosinophils. We hypothesized that eosinophils are retained in the bronchial vasculature in the inner airway wall during bronchoconstriction because of deformation of the mucosal membrane. To test this hypothesis we induced unilateral bronchoconstriction in open chest guinea pigs by stimulating the right vagus nerve and compared the accumulation of eosinophils in the airway wall of the constricted and contralateral unconstricted lungs using histologic specimens. Results show that the density of eosinophils (number of cells/wall area) significantly increased in the inner wall and decreased in the adventitia of the constricted airways compared with the contralateral unconstricted airways. There was a positive relationship between the amount of smooth muscle shortening and the eosinophil density in the inner wall. On the other hand, this relationship was significantly negative in the adventitia. Atropine completely inhibited the eosinophil accumulation in the inner wall. These data suggest that eosinophils can accumulate in the airway inner wall during bronchoconstriction because of geometrical factors.

Effect of mechanical deformation on structure and function of polymorphonuclear leukocytes

The present studies were designed to test the hypothesis that mechanical deformation of polymorphonuclear leukocytes (PMN) leads to functional changes that might influence their transit in the pulmonary capillaries. Human leukocytes were passed through 5- or 3-micron-pore polycarbonate filters under controlled conditions. Morphometric analysis showed that the majority of PMN were deformed and that this deformation persisted longer after filtration through 3-micron filters than through 5-micron filters (P < 0.05) but did not result in the cytoskeletal polarization characteristic of migrating cells. Flow cytometric studies of the filtered PMN showed that there was a transient increase in the cytosolic free Ca2+ concentration after both 3- and 5-micron filtration (P < 0.01) with an increase in F-actin content after 3-micron filtration (P < 0.05). Although L-selectin expression on PMN was not changed by either 5- or 3-micron filtration, CD18 and CD11b were increased by 3-micron filtration (P < 0.05). Priming of the PMN with N-formyl-methionyl-leucyl-phenylalanine (0.5 nM) before filtration resulted in an increase of CD11b by both 5 (P < 0.05)- and 3-micron (P < 0.01) filtration. Neither 5- nor 3-micron filtration induced hydrogen peroxide production. We conclude that mechanical deformation of PMN, similar to what occurs in the pulmonary microvessels, induces both structural and functional changes in the cells, which might influence their passage through the pulmonary capillary bed.

The inflammatory response and extracorporeal circulation

Defining the cause of organ and tissue dysfunction associated with the use of perfusion systems will produce methods of prevention or treatment and improve patient outcome. The problem is the plethora of triggers, effectors, and mediators in this process, which can now be measured. Each new measureable compound becomes another biochemical "smoking gun" without physiological data to show any relevance to the human problem. This review critically compares and contrasts the role of certain, largely novel, initiation, amplification, and cytotoxic mechanisms in the inflammatory response of the myocardium and pulmonary systems after a period of cardiopulmonary bypass. The available evidence strongly points to the process being different for each of these tissue beds. These data suggest that ensuring normal lung and heart functions after surgery will require separate therapeutic strategies.

Adhesion molecules in lung diseases

The human body possesses highly specialized cellular defense mechanisms that, when activated pathologically, can induce a number of immunologic disorders. For a normal cellular immune response, the following conditions must be fulfilled: (1) accumulation of white blood cells, (2) their diapedesis through the vessel walls of the inflammatory area affected by an injurious agent, and (3) normal cellular effector functions in the tissue. This cascade of inflammatory processes has recently been shown to be regulated by a group of molecules that are termed adhesion molecules and consist of three subfamilies: selectins, the immunoglobulin supergene family, and integrins. The cellular functions influenced by adhesion molecules include, among others, cytotoxic T-cell responses, CD4-dependent activation of B lymphocytes by T lymphocytes, activation of granulocytes and macrophages, phagocytosis of opsonized particles by monocytes, macrophages, and granulocytes, antigen-presenting function of macrophages, their antibody-dependent cytotoxicity, initiation of a respiratory burst by white blood cells, and activation of fibroblasts. Studies performed in recent years have shown that pathogenetically relevant changes in the expression and function of adhesion molecules are involved in a variety of pulmonary diseases. These changes include the accumulation and activation of alveolar macrophages in smokers, experimentally induced bronchial hyperreactivity in bronchial asthma, accumulation of eosinophils in allergic rhinitis, bleomycin-induced pulmonary fibrosis, binding of viruses and bacteria to respiratory mucosa, and various mechanisms of acute damage to pulmonary parenchyma. Though their role in tumor development is still unclear, adhesion molecules are obviously involved in determining the route and organotropism of metastases. Further studies of the function of adhesion molecules in pulmonary diseases will contribute to our understanding of the pathomechanisms of these diseases and, through the development of specific antibodies, may provide attractive new therapeutic approaches to problems for which treatment is not yet available.

Factors affecting neutrophil transit during acute pulmonary inflammation: minireview

Recent studies confirm data that for over a century have suggested that the lungs are an important source of noncirculating neutrophils. Many factors control how neutrophils pass through the normal lungs, including the unique and complex structure of the pulmonary capillary bed, local hemodynamic factors, neutrophil deformability, and neutrophil-endothelial interactions. Alterations in these factors are likely to influence neutrophil traffic in the lungs in disease processes where neutrophil-induced lung injury has been implicated. In recent years experimental approaches using in vitro techniques have been used to study neutrophil function. Such studies, together with in vivo studies in whole animals and to a limited extent in humans, will help to elucidate the important mechanisms in neutrophil sequestration in the acute and chronically inflamed lung. Novel avenues of therapeutic intervention in neutrophil traffic through the lungs may then be possible. However, whether interference with this cell, which forms a major defense mechanism in the lungs, is advisable, remains a matter for debate.

New perspectives on basic mechanisms in lung disease. 2. Neutrophil traffic in the lungs: role of haemodynamics, cell adhesion, and deformability

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Neutrophil retention in the lungs of patients with chronic obstructive pulmonary disease

In order to study neutrophil traffic in the lungs of humans, we harvested autologous neutrophils and radiolabeled them with indium-111 prior to reinjection. The passage of these [111In]neutrophils through the pulmonary vasculature was compared with that of [99mTc]erythrocytes in normal elderly subjects and in patients with chronic obstructive pulmonary disease (COPD). Neutrophil sequestration within the lungs of seven normal subjects, 10 min after reinjection, correlated with local erythrocyte transit times in the lungs (tau = 0.72, p less than 0.001). This relationship was lost in patients with COPD. In seven patients studied during an acute exacerbation of COPD, neutrophil retention was higher during the first passage through the lungs (mean, 22.0 SD 14.1%) compared with 14 patients studied when their condition was stable (16.3 SD 3.4%, p less than 0.001), or to the normal elderly subjects (13.7 SD 7.0%, p less than 0.001). In addition, the subsequent rate of neutrophil washout from the lungs was slower in patients with acute COPD (1.93 SD 0.66 x 10(-3)s1) than in those with stable disease (3.08 SD 1.8 x 10(-3)s-1, p less than 0.02). Neutrophil retention in the lungs correlated inversely with the extent of emphysema, assessed quantitatively by CT scanning (tau = 0.68, p less than 0.05). Thus, patients presenting with acute exacerbations of COPD have an increased neutrophil burden in the pulmonary vasculature with the potential for increased lung proteolysis.