Pulmonary hypertension in rheumatic mitral stenosis revisited

BACKGROUND

In patients with mitral stenosis (MS), pulmonary hypertension (PH) is a significant contributor to the associated morbidity. We aimed to study factors associated with the presence of significant PH (sPH) and whether incorporating body surface area (BSA) in the mitral valve area (MVA) would improve the predictive value of the latter.

METHODS

The medical records of 558 patients with severe MS undergoing percutaneous balloon mitral commissurotomy were evaluated over a period of 8 years. Factors associated with the presence of significant PH (sPH) defined as mPAP ≥ 40 mm Hg were examined.

RESULTS

A total of 558 patients (423 women) were enrolled. Overall, 153 (27%) patients had sPH. Patients with sPH were similar to the rest of the subjects in terms of demographics, body habitus, blood group, and incidence of atrial fibrillation. Among echocardiographic findings, absolute MVA, indexed MVA, and mean transmitral valve gradient were associated with the presence of sPH. Transmitral valve gradient during right heart catheterization had the highest area under the curve for an association with sPH.

CONCLUSION

Age, gender, heart rhythm, and blood group were not associated with the presence of sPH in severe MS. The predictive value of the indexed MVA for the presence of sPH was not higher than that of absolute MVA.

Association of ABO blood types with the risk of in-stent restenosis

OBJECTIVES

To investigate the prevalence of in-stent restenosis (ISR) in patients with various ABO blood types.

METHODS

Clinical information from 150 patients with a confirmed diagnosis of ISR and 150 patients with a diagnosis of patent coronary stents in the secondary angiography was collected. Comprehensive demographic and laboratory data, including ABO and Rhesus blood groups, as well as comorbid conditions and vessel and stent characteristics, were recorded for each patient. The association of ABO blood groups with the risk of ISR before and after controlling for coronary risk factors was determined. Categorical data were analyzed with the Chi-square test and numerical values were analyzed with t-tests. Binary logistic regression models were constructed to compare type A and non-A for the frequency of risk factors.

RESULTS

A total of 392 stents were implanted in 300 patients. Two hundred and fourteen stents (54.6%) were patent and 178 stents (45.4%) were stenosed. Blood group A was significantly more common in the ISR group (43.3% vs. 28.7%, p=0.03). However, the frequencies of other blood types, as well as Rh antigen, were similar between the two groups. Triglyceride and low-density lipoproteins were the only significantly different variables (221 ± 198 mg/dL vs. 138 ± 76 mg/dL, p<0.001 and 108 ± 36 mg/dL vs. 96 ± 73 mg/dL, p=0.04, in type-A vs. non-A, respectively). After matching for coronary risk factors, there was no difference between A blood type patients and their controls.

CONCLUSION

ISR is significantly more prevalent in individuals with the type A blood group. However, this higher association is most likely due to higher atherogenic conditions in patients within this population.

Outcomes-based systematic review for management of massive intra-cardiac or pulmonary thrombotic emboli during surgery

INTRODUCTION

The management of massive intra-operative embolism remains controversial. Our hypothesis was that either surgical or medical thrombectomy offers survival benefit in these patients.

METHODS

Published case reports were reviewed for intra-operative intra-cardiac or pulmonary embolism and outcomes for the following four intervention groups were evaluated for mortality benefit: surgical embolectomy; thrombolysis; anticoagulation; supportive care alone. We also assessed whether the use of diagnostic modalities prior to each embolism event resulted in a mortality benefit and, separately, whether post-intervention improvement in physiologic parameters resulted in improvement in outcomes. Univariate analyses and logistic regression were performed to assess the impact of the four primary interventions on mortality, the primary outcome.

RESULTS

Seventy-eight cases were reviewed and therapeutic interventions resulted in improved survival (70%) compared to supportive care (45%), odds ratio=0.38[0.15-0.98], p=0.04. Univariate analysis of primary interventions with death as a primary outcome resulted in a lack of significantly different outcomes (p=0.08). Mortality rates were 71% in the thrombolytic; 28% in surgical embolectomy; 18% in anticoagulation and 43% in the supportive care groups. The routine pre-event use of trans-esophageal echocardiography was not related with improved outcomes (p=0.36) but the use of pulmonary artery or central venous catheters was (p=0.035). Post-intervention improvements in the physiologic parameters of each diagnostic modality were associated with an improvement in mortality (p<0.05).

CONCLUSIONS

Our data present some important trends among the intervention groups, raising significant concerns about the safety for the use of thrombolytics in the management of intra-operative embolism.

Prognostic utility of hypothermic machine perfusion in deceased donor renal transplantation

Pulsatile pump perfusion of kidney transplants is known to decrease delayed graft function (DGF) and improve 1 year graft survival when compared to static cold preservation. Kidneys with better flow and resistance parameters on perfusion are likely to have a better post transplant function. These parameters are commonly used to evaluate kidneys being considered for transplantation. This study assesses the time frame for a kidney within which it reaches optimal perfusion parameters. All kidneys pumped between 5/2006 and 9/2009 on a Lifeport© kidney transporter at our local organ procurement agency were studied. 190 kidneys were evaluated and then divided into two groups based on whether terminal flows increased or declined after prolonged perfusion. All kidneys were assessed for changes in flow (F), resistance (R) and temperature at 15 minute intervals. Discards, DGF and one year graft survival were noted. The Student paired t test and Chi-square analysis were used to compare data. A multiple logistic regression analysis was performed to study independent predictors of DGF on pump perfusion.

RESULTS

For all kidneys, the mean initial flow was 59 ± 35 mL/min which improved to an average flow of 128 ± 38 mL/min with continued perfusion. The maximal flow and terminal flows were 148 ± 51 and 135 ± 38 mL/min respectively. The flows at 2, 4, and 6 hours was 125 ± 41, 128 ± 42 and 130 ± 39 mL/min respectively. Kidneys that improved on continued perfusion had a significantly lower discard rate (20 vs 34% p < 0.05), but a higher incidence of DGF (64 vs 39%, P < .05). One year graft loss (death censored) was comparable in the two groups. (4/42 vs. 3/33, P = .94). Resistance at 2, 4, and 6 hours was predictive of DGF, as was donor anoxia and cerebrovascular accident (CVA) as the cause of death.

CONCLUSIONS

Kidneys on pulsatile pump perfusion tend to show improved flows and decreased resistance over time. The average flow for a kidney is reached by 2 hours. Those kidneys that start with lower flow rates that improve after 2 hours with continued perfusion are less likely to be discarded but are still associated with a greater incidence of delayed graft function. Resistance at 2 hours predicts DGF while initial resistance predicts one year graft survival.

Effect of increased pressure during pulsatile pump perfusion of deceased donor kidneys in transplantation

INTRODUCTION

Pulsatile pump perfusion of potential kidneys for transplantation is known to decrease the rate of delayed graft function (DGF) and improve their 1-year survival. Flow and resistance parameters are often used to determine the suitability of kidneys for transplantation. Kidneys with low flow rates are often subjected to higher pressures to improve flow. This study evaluated the effect of higher pump pressures on posttransplant renal function.

METHODS

We performed a retrospective analysis of 73 deceased donor kidneys preserved using pump perfusion (LifePort) at our center between May 2006 and September 2009. We calculated the mean pump pressure (MP) for the duration of perfusion of each kidney, using systolic pressure (SP) and diastolic pressure (DP) readings with the following formula: (MP = DP + 1/3 (SP - DP). The kidneys were divided into a low (LP; n = 49) and a high-pressure group (HP; n = 24) based on a MP cutoff value of 23 mm Hg. The two groups were then compared for differences in perfusion dynamics and primary endpoints including DGF and 1-year graft survival. Statistical analysis was performed using paired Student t test and chi-square analysis.

RESULTS

The two groups were comparable for donor age, extended criteria, sensitization, and cold ischemic times. They differed significantly in higher initial (0.65 ± 0.4 versus 0.4 ± 0.2, P = .01), average (0.25 ± 0.08 versus 0.18 ± 0.06, P = .0006), and terminal resistance (0.21 ± 0.07 versus 0.17 ± 0.06, P = .008) of HP versus LP kidneys. Flow rates were comparable between the two groups. DGF was higher in HP kidneys (75% versus 40%, P = .006) with similar 1-year graft survival (87.5% versus 89%, P = .7).

CONCLUSIONS

Perfusate flow through a kidney can be improved by increasing pressure settings to overcome elevated resistance. This maneuver was not associated with a lower rate of DGF after transplantation. One-year graft survival remained unaffected.

Alteration in respiratory physiology in obesity for anesthesia-critical care physician

Obesity is known to be a major risk factor of a whole range of cardiovascular, metabolic and respiratory disorders. The pattern of regional fat distribution plays an important role in the pre-disposition of obese subjects to respiratory complications. Obesity is responsible for important changes in respiratory function both during spontaneous breathing as well as during general anesthesia and mechanical ventilation. The most characteristic abnormalities consist of decreased functional residual capacity, reduced expiratory reserve volume, decreased compliance and increased resistance of the respiratory system. Breathing at low lung volume promotes airway closure in the dependent lung zones with consequent gas exchange abnormalities even though lung carbon monoxide-diffusing capacity is normal or increased. Weight loss can reduce many of the alterations in pulmonary function related to obesity.

High volumes of intravenous fluid during cardiac surgery are associated with increased mortality

INTRODUCTION

Positive fluid balance during abdominal surgery has been associated with increased morbidity. We hypothesized that administration of large volumes of intravenous fluids in cardiac surgery is associated with increased mortality.

METHODS

Retrospective analysis of data on 1358 patients who underwent cardiac surgery from 2001 to 2005 at two major hospitals in Western New York. Patients were divided in to those who received intravenous fluids above the median volume (3.9 L) and those who received less than the median volume of intra-operative fluid. Acute Kidney Injury Network criteria based on serum creatinine were used to define Acute Kidney injury.

RESULTS

Logistic regression and Cox-proportional models showed increased 90 day mortality (HR -2.8, 95% CI -1.16-7.01) in those patients who received greater than the median volume of intravenous during cardiac surgery. This was confirmed with propensity score analysis. Furthermore, the marginal effects analysis revealed that after about 4.0 liters of intravenous fluid, the survival probability falls significantly in cardiac surgery patients.

CONCLUSIONS

Administration of large volumes of intra-operative intravenous fluid is independently associated with an increase in 90 day mortality in cardiac surgery.

High-sensitivity C-reactive protein (hs-CRP) and tumor necrotizing factor-alpha (TNF-alpha) after on- and off- pump coronary artery bypass grafting

INTRODUCTION

Coronary artery bypass grafting (CABG) is one of the most frequently performed operations around the world. The aim of this study is to evaluate high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-alpha (TNF-alpha) differences between on-pump and off-pump coronary surgery.

METHODS

In this prospective study, 90 patients with coronary artery disease referred for CABG were enrolled from July 2006-November 2007. Levels of hs-CRP and TNF-alpha were measured by ELISA using commercial kits

RESULTS

hs-CRP levels significantly (p<0.001) increase after CABG. But no difference between off-pump and on-pump groups was noted for hs-CRP and TNF-alpha levels (p=0.4, p=0.8).

CONCLUSIONS

There was no difference in high-sensitivity C-reactive protein (hs-CRP) and TNF-alpha between on-pump and off-pump CABG surgery.

Clonidine suppresses plasma and cerebrospinal fluid concentrations of TNF-alpha during the perioperative period

The analgesic properties of alpha(2)-agonists are well known. In experimental models, tumor necrosis factor (TNF)-alpha regulates adrenergic responses in the brain. Constitutive TNF-alpha, in brain regions involved in pain perception, is decreased after the administration of clonidine. We investigated patients undergoing lower-extremity revascularization. Seven patients were treated with clonidine 0.2 mg per os (low), and three patients received 0.4 mg per os clonidine (high) before surgery. Eight patients received placebo and served as controls. Continuous spinal anesthesia was provided by insertion of a pliable catheter into the subarachnoid space. Baseline plasma and cerebrospinal fluid (CSF) samples were obtained before injection of local anesthetic. Samples were analyzed for TNF-alpha using a biologic assay. Systemic and central release of catecholamines were assessed by high-pressure liquid chromatography measurement of norepinephrine in plasma and CSF, vanillylmandelic acid and methoxy hydroxyl phenyl glycol in 24-h urinary excretion, respectively. Clonidine 0.2 mg pretreatment decreased TNF-alpha concentrations both in plasma and CSF. Patients receiving clonidine had lower pain visual analog scale scores and required less morphine compared with the Placebo group (P < 0.01). Preoperative administration of clonidine decreased catecholamine release in the periphery, as well as in the central nervous system. A smaller norepinephrine concentration in plasma and CSF, and less secretion of vanillylmandelic acid (P < 0.01) and methoxy hydroxyl phenyl glycol in the urine, were observed. Larger dose clonidine (0.4 mg) resulted in no detectable TNF-alpha in CSF. These results suggest that an interaction between TNF-alpha and the function of adrenergic neurons in the central nervous system may contribute to the sedative and analgesic effects of adrenergic agonists.

IMPLICATIONS

Preoperative administration of clonidine decreases both plasma and cerebrospinal fluid concentrations of inflammatory cytokines, resulting in perioperative analgesia and decreased sympathetic tone.

Clonidine suppresses plasma and cerebrospinal fluid concentrations of TNF-alpha during the perioperative period

The analgesic properties of alpha(2)-agonists are well known. In experimental models, tumor necrosis factor (TNF)-alpha regulates adrenergic responses in the brain. Constitutive TNF-alpha, in brain regions involved in pain perception, is decreased after the administration of clonidine. We investigated patients undergoing lower-extremity revascularization. Seven patients were treated with clonidine 0.2 mg per os (low), and three patients received 0.4 mg per os clonidine (high) before surgery. Eight patients received placebo and served as controls. Continuous spinal anesthesia was provided by insertion of a pliable catheter into the subarachnoid space. Baseline plasma and cerebrospinal fluid (CSF) samples were obtained before injection of local anesthetic. Samples were analyzed for TNF-alpha using a biologic assay. Systemic and central release of catecholamines were assessed by high-pressure liquid chromatography measurement of norepinephrine in plasma and CSF, vanillylmandelic acid and methoxy hydroxyl phenyl glycol in 24-h urinary excretion, respectively. Clonidine 0.2 mg pretreatment decreased TNF-alpha concentrations both in plasma and CSF. Patients receiving clonidine had lower pain visual analog scale scores and required less morphine compared with the Placebo group (P < 0.01). Preoperative administration of clonidine decreased catecholamine release in the periphery, as well as in the central nervous system. A smaller norepinephrine concentration in plasma and CSF, and less secretion of vanillylmandelic acid (P < 0.01) and methoxy hydroxyl phenyl glycol in the urine, were observed. Larger dose clonidine (0.4 mg) resulted in no detectable TNF-alpha in CSF. These results suggest that an interaction between TNF-alpha and the function of adrenergic neurons in the central nervous system may contribute to the sedative and analgesic effects of adrenergic agonists.

IMPLICATIONS

Preoperative administration of clonidine decreases both plasma and cerebrospinal fluid concentrations of inflammatory cytokines, resulting in perioperative analgesia and decreased sympathetic tone.

Role of macrophage inflammatory protein-2 in aspiration-induced lung injury

OBJECTIVE

To determine the role of the chemokine, macrophage inflammatory protein (MIP)-2, in the pathogenesis of aspiration-induced lung injury in the rat.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University research laboratories.

SUBJECTS

Adult, male Long-Evans rats.

INTERVENTIONS

Anesthetized rats underwent induction of lung injury by well-described models of aspiration triggered by intra-tracheal delivery of acid alone, gastric particles alone, or the combination. After injury, induction of MIP-2 messenger RNA in whole lungs and immunoreactive MIP-2 in bronchoalveolar lavage (BAL) fluids was determined. The contribution of MIP-2 to BAL fluid chemotactic activity was defined by using an in vitro chemotaxis assay. The in vivo effect of blocking MIP-2 on pulmonary vascular leak, BAL fluid neutrophils, PaO2/FIO2 ratio, and alveolar-arterial oxygen tension gradient in acid-induced lung injury was determined.

MEASUREMENTS AND MAIN RESULTS

Induction of MIP-2 messenger RNA and protein over time was observed in response to all three stimuli. A significant portion (25% to 41%) of the chemotactic activity in BAL fluids from injured rats was inhibited by anti-MIP-2 antibody. After acid injury, blocking of MIP-2 was associated with a 53% decrease in BAL fluid neutrophils and a 33% decrease in pulmonary vascular leak. Although acid injury both impaired oxygenation and increased venous admixture, in vivo blocking of MIP-2 was associated with improved oxygenation as well as decreased venous admixture.

CONCLUSIONS

MIP-2 was up-regulated during the development of aspiration-induced lung injury in rats. MIP-2 contributed to lung accumulation of neutrophils via a chemotactic mechanism. Although oxygenation and venous admixture are worsened by acid-induced lung injury in vivo, blocking of MIP-2 at the onset of injury improved these physiologic alterations. Because the aspiration event often is witnessed, chemokines may be valid therapeutic targets for inhibiting the subsequent inflammatory response.

Acid aspiration increases sensitivity to increased ambient oxygen concentrations

Previously we have demonstrated that prolonged exposure to 100% ambient oxygen leads to a marked loss in functional lung volume and lung compliance, hypoxemia, and surfactant system abnormalities similar to acute respiratory distress syndrome (ARDS). However, 50% oxygen administration is believed to be safe in most clinical settings. In the present study, we have evaluated the effects of a 24-h exposure to 50% oxygen in rabbits immediately following experimental gastric acid aspiration. Mild hypoxemia, but no changes in mortality, lung volume, lung compliance, surfactant metabolism, or edema formation occurred after 24 h of normoxia postacid aspiration. Conversely, a relatively short (24-h) exposure to 50% oxygen after acid aspiration results in increased pulmonary edema, physical signs of respiratory distress, and mortality, as well as decreased arterial oxygenation, lung volume, lung compliance, and type II alveolar cell surfactant synthesis. These results suggest that acid aspiration alters the "set point" for oxygen toxicity, possibly by "priming" cells through activation of inflammatory pathways. This pathogenic mechanism may contribute to the progression of aspiration pneumonia to ARDS.

Systemic perfluorocarbons suppress the acute lung inflammation after gastric acid aspiration in rats

Perflurocarbons (PFCs) are used during liquid ventilation and as hemoglobin substitutes. PFCs reduce free radical generation and damage to the lung during liquid ventilation. Thus, we examined the effects of parenteral administration of PFCs on lung injury after acid aspiration. Rats were treated with intraperitoneal injection of either FC-77 or IV injection of Fluosol. Controls received intraperitoneal or IV normal saline (NS) before or at the time of injury and then were injured by instillation of NS + HCl (pH = 1.25) into their lungs via a tracheotomy. The animals were exposed to air or 98% oxygen, breathing spontaneously. The rats were injected with 0.05 microCi of (125)I-albumin (bovine serum albumin) before injury. The extent of lung injury was assessed 5 h postinjury by compliance and lung albumin permeability index measurement. Myeloperoxidase (MPO) activity and histologic examination were used to assess neutrophilic infiltration. Both FC-77 and Fluosol decreased the permeability index compared with controls (1.05 +/- 0.08; 1.08 +/- 0. 12, respectively, versus 1.34 +/- 0.21) and improved lung compliance after intratracheal instillation of 1.2 mL/kg of HCl/NS, pH = 1.25 + hyperoxia injury (P < 0.05). Lung MPO activity decreased in the FC-77 group and was associated with a concomitant decrease in neutrophil infiltration. MPO activity of the spleen increased after FC-77 treatment. The administration of FC-77 decreased the severity of lung permeability changes associated with acid in the presence or absence of hyperoxia exposure. These data suggest that attenuation of neutrophilic infiltration by PFCs decreases lung injury.

IMPLICATIONS

Intraperitoneally administered perfluorocarbons in rats attenuate the neutrophilic infiltration in the lung after acid aspiration, thereby decreasing the alveolar protein leakage and improving pulmonary compliance.

Blood product use in cardiac revascularization: comparison of on- and off-pump techniques

BACKGROUND

Cardiac revascularization on a beating heart avoids the side effects of cardiopulmonary bypass (eg, neurologic injury, hemodilution, and coagulopathy). We examined perioperative bleeding and use of blood products during coronary artery bypass grafting using either on-pump or off-pump techniques.

METHOD

The charts of 126 patients who had coronary artery bypass grafting were reviewed. Data from 66 patients revascularized off pump and 60 patients with cardiopulmonary bypass (on pump) were analyzed using unpaired Student's t test.

RESULTS

Average age was 62.5 years in either group. More patients received heparin preoperatively in the off-pump group that resulted in mild elevation of preoperative partial thromboplastin time and activated clotting time (40.4 +/- 2.9 seconds and 150.1 +/- 5.3 seconds, respectively). However, the off-pump group had less perioperative (intraoperative or postoperative) bleeding (2312 +/- 212 mL versus 3251 +/- 155 mL, p < 0.05) and required fewer blood products compared with the on-pump group. Hemoglobin and platelets decreased more in the conventional on-pump group.

CONCLUSIONS

Avoiding cardiopulmonary bypass decreases perioperative bleeding and, consequently, reduces the use of blood products after coronary artery bypass grafting, which might result in fewer transfusion-related complications.

High-dose nitric oxide inhalation increases lung injury after gastric aspiration

BACKGROUND

Inhaled nitric oxide is often used in patients with adult respiratory distress syndrome. However, nitric oxide also may be significantly toxic, especially if administered concurrently with hyperoxia. The authors evaluated the isolated effect of nitric oxide and the combined effects of nitric oxide and hyperoxia on lung injury in rats after acid aspiration.

METHODS

Animals were injured by instillation of 1.2 ml/kg hydrogen chloride in low-pH saline (the acid group) or acidified gastric particles (the casp group) into the lungs under halothane anesthesia via a tracheal catheter. Controls received no injury vehicle but rather underwent the surgical process. After recovery from anesthesia, the animals were exposed to 20% or 90% oxygen with or without 20, 40, or 80 ppm nitric oxide for 5 h. The permeability index, alveolar-arterial oxygen difference, the ratio of oxygen pressure to the inspired fraction of oxygen, and the ratio of wet to dry weight were assessed 5 h after injury as indices of lung injury. Data were assessed using analysis of variance.

RESULTS

Each group included 6-10 rats. Exposure to nitric oxide (80 ppm) in air increased protein permeability in the lungs to a permeability index of 1.42+/-0.12 after acid aspiration. The combination of nitric oxide (80 ppm) and hyperoxia further increased protein leakage to a permeability index of 2.1+/-0.25. Exposure to lower concentrations of nitric oxide (e.g., 20 and 40 ppm) increased the permeability index of the lungs (1.44+/-0.21, 1.75+/-0.29, respectively) in the presence of hyperoxia, although it did not affect the permeability index of the lungs during exposure to air. Pretreatment of animals with deferoxamine and methylene blue partially inhibited the adverse effect of hyperoxia and nitric oxide, which suggested a complex underlying mechanism involving both reactive-species generation and pulmonary vasomotor changes.

CONCLUSIONS

These results show that inhaled nitric oxide at 80 ppm for a short duration (5 h) increases the severity of the inflammatory microvascular lung injury after acid aspiration. The pulmonary damage is exacerbated further in the presence of high oxygen concentrations. Although lower concentrations of nitric oxide did not increase the extent of lung injury, longer exposure times need to be assessed.

Postoperative anisocoria in a patient undergoing endoscopic sinus surgery

OBJECTIVE

Anisocoria after sinus surgery can be related to serious complications such as intraorbital hematoma or increased intracranial pressure secondary to an expanding hematoma.

CASE REPORT

A 51-year-old man underwent endoscopic surgery of sinuses, and developed anisocoria; likely a result of the local spread of cocaine used to provide local anesthesia and vasoconstriction. The localized effect of this anesthetic agent produced a typical picture of nasociliary ganglion block that subsided in a few hours. In the results, the nasociliary nerve block was noticed on recovery from anesthesia with no other neurologic deficit. Ophthalmologic examination demonstrated a short-lasting anisocoria with loss of accommodation and sensory block over the tip of the nose.

CONCLUSION

The central spread of the local anesthetics should be considered as a differential diagnosis of unexplained anisocoria, especially when it is associated with loss of corneal reflex.

The role of tumor necrosis factor-alpha in the pathogenesis of aspiration pneumonitis in rats

BACKGROUND

Aspiration pneumonitis is characterized by proteinaceous pulmonary edema and acute infiltration of neutrophils into the alveolar space. This study examined the role of the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), on the pathogenesis of the injury produced by the different components that may be present in the aspirate, acid, or gastric particles.

METHODS

Rats were injured by intratracheal instillation of a vehicle containing acid or gastric particles. TNF-alpha concentration of bronchoalveolar lavage fluid was determined using a bioassay. upregulation of lung TNF-alpha mRNA was also measured. The effect of intratracheal anti-rat TNF-alpha treatment was assessed by lung protein permeability, blood gases, and lung myeloperoxidase activity.

RESULTS

Injury vehicle alone and acid injury resulted in a small TNF-alpha peak 1-2 h after injury in the lavage fluid. Both particulate and acidic particulate groups produced a much more robust TNF-alpha signal that reached a plateau at 2-4 h after injury and declined at 8 h. Upregulation of TNF-alpha mRNA was only detected in the particulate-containing groups. Acidic particulate exposure yielded a synergistic increase in protein permeability and decrease in blood oxygenation. Anti-TNF-alpha treatment reduced protein permeability and myeloperoxidase activity and increased blood oxygenation in the groups exposed to only acid. Such treatment had no effect on either of the particulate containing injuries.

CONCLUSIONS

TNF-alpha is differentially manifested according to the components that make up the aspirate but the levels of TNF-alpha expression do not correlate with the severity of the resultant injury. However, the reduction in acid-induced lung injury by anti-TNF-alpha treatment indicates that TNF-alpha plays a role in the pathogenesis of aspiration pneumonitis.