Transient increase in interleukin-8 and pulmonary microvascular permeability following aortic surgery

Effect of N-acetylcysteine on cardiac injury and oxidative stress after abdominal aortic aneurysm repair: a randomized controlled trial

BACKGROUND

Several studies have reported that the antioxidant properties of N-acetylcysteine (NAC) can provide cardiac protection through scavenging of free radicals. The present study was aimed to assess the efficacy of NAC for cardiac protection in patients undergoing elective abdominal aortic aneurysm (AAA) repair.

METHODS

Fifty adult patients undergoing (AAA) repair were randomly allocated to receive NAC infusion (n = 25) or placebo infusion (n = 25). NAC infusion in group I (NAC group) was started at a rate of 0.3 mg/kg/min intravenously during surgery then decreased to a rate of 0.2 mg/kg/min for 24 h post-operatively. Group II (placebo group) received an equivalent rate of placebo infusion. The following parameters: myocardial-specific protein troponin-I, creatine phosphokinase-MB (CPK-MB), plasma pro-inflammatory cytokines [tumour necrosis factor-α (TNF-α) and interleukin (IL)-1β], were assessed at the following time points: preoperatively and at 1 h, 12 h, 24 h, 48 h, and 96 h after surgery. Furthermore, serum malondialdehyde (MDA) and total antioxidant capacity (TAC) were measured preoperatively as a baseline, during aortic clamping, 30 min after declamping, at the end of surgery, 2 h after surgery, 12 h after surgery, and 24 h after surgery.

RESULTS

NAC infusion patients had significantly lower post-operative concentrations of myocardial-specific protein [cTnI, CPK-MB] and pro-inflammatory cytokines [TNF-α, IL-1β]. In addition, MDA level was less and TAC was higher in patients who received NAC infusion.

CONCLUSION

NAC infusion provided cardiac protection through scavenging of oxygen free radicals.

Update on transfusion solutions during surgery: review of hydroxyethyl starches 130/0.4

OBJECTIVES

Restoration of circulation is crucial in the surgical patient management. Colloids and crystalloids are widely used for blood volume therapy. We reviewed recent trials to evaluate efficacy and safety of hydroxyethyl starch (HES) 130/0.4 during surgery.

MATERIAL AND METHODS

A subjective, not systematic, review of literature was performed. Papers were searched to answer questions about efficacy of HES, its impact on coagulation and inflammation and its effects on pulmonary mechanics and renal function.

CONCLUSIONS

HES 130/0.4 is effective for volume therapy and is less expensive than human albumin. Its effects on coagulation and renal function are manageable; it may ameliorate pulmonary permeability and reduce inflammation.

Effect of ulinastatin on cytokine reaction during gastrectomy

Background

Inflammation plays an important role in the postoperative morbidity of organs, which is related to the activation of pro-inflammatory and anti-inflammatory cytokines. Ulinastatin (Urinary trypsin inhibitor, UTI) is a serine protease inhibitor found in human urine or serum that inhibits the activation of human leukocyte elastase. This study examined the effect of UTI on the inflammation response in patients undergoing a gastrectomy.

Methods

Thirty patients scheduled to undergo a gastrectomy were divided into two groups as follows: Control group (untreated, n = 15) and UTI group (100,000 units of UTI were continuously injected intravenously for 2 hours, n = 15). Arterial blood was sampled before surgery (T0), 10 minutes after its onset (T1), at its end (T2), and 1 hour after surgery (T3) to measure the level of cytokines.

Results

Both the control and treatment groups had higher interleukin (IL)-6 levels at T2 and T3 than T0, and the level increased with time. However, the increase was smaller in the treatment group. The IL-8 levels were not activated significantly in any of the groups.

Conclusions

UTI inhibits the secretion of IL-6, which is an inflammatory cytokine produced after a gastrectomy. This shows that UTI can decrease the inflammation reaction caused by surgical stress.

A comparative study of myocardial injury during conventional and endovascular aortic aneurysm repair: measurement of cardiac troponin T and plasma cytokine release

BACKGROUND

Major aortic surgery results in significant haemodynamic and oxidative stress to the myocardium. Cytokine release is a major factor in causing cardiac injury during aortic surgery. Endovascular aortic aneurysm repair (EVAR) has the potential to reduce the severity of the ischaemia reperfusion syndrome and its systemic consequences.

AIM

The aim of this study was to investigate the occurrence of myocardial injury during conventional and endovascular abdominal aortic aneurysm repair using measurement of the myocardial-specific protein, cardiac troponin T. Interleukin-6 was also measured in both groups and haemodynamic responses to surgery assessed.

METHODS

Nine consecutive patients undergoing conventional infra-renal aortic aneurysm surgery were compared with 13 patients who underwent EVAR. Patients were allocated on the basis of aneurysm morphology and suitability for endovascular repair.

RESULTS

Patients undergoing open repair had significantly more haemodynamic disturbance than those having endovascular repair (mean arterial pressure at 5 min following unclamping or balloon deflation: open (69.6 + 3.3 mmHg); endovascular (86 + 4.4 mmHg), P < 0.05 vs. pre-op). Troponin T levels at 48 h post-operatively were higher in patients who underwent open repair (open 0.164 + 0.1 ng/ml; endovascular 0.008 + 0.0005 ng/ml, P < 0.04). Significantly more patients in the open repair group had troponin T levels > 0.1 ng/l when compared with the endovascular group (P < 0.01, chi (2) test)

CONCLUSION

Endovascular aortic surgery produces significantly less myocardial injury than the open technique of aortic aneurysm repair.

A Global Assessment of the Inflammatory Response Elicited Upon Open Abdominal Aortic Aneurysm Repair

The inflammatory response during elective open infrarenal abdominal aortic aneurysm repair and its impact on outcome is investigated. Twenty high-risk patients were enrolled, and blood samples were obtained at 8 perioperative time points. Endotoxin, cytokines (tumor necrosis factor-α and interleukin-1β, and interleukin-6), CD11b expression, and nitric oxide were measured. Peak endotoxin levels occurred within 30 minutes of reperfusion and were higher among patients developing complications. Interleukin-6 levels increased during reperfusion, reaching a peak on the first postoperative day. Interleukin-6 increase correlated with aortic clamp time and morbidity. CD11b expression increased 30 minutes after reperfusion, and this effect was greater among patients who developed complications. Endotoxin may be important in the pathogenesis of multiple organ dysfunction syndrome. Activated neutrophils may have a central role in tissue injury after reperfusion. Intraoperative CD11b upregulation may be an early marker for postoperative complications after infrarenal abdominal aortic aneurysm repair.

Increased pulmonary capillary permeability and extravascular lung water after major vascular surgery

INTRODUCTION

We decided to investigate the pathogenesis of pulmonary ventilatory and radiographic abnormalities in patients after major vascular surgery.

PATIENTS AND METHODS

Sixteen mechanically ventilated patients without heart failure were studied, within 3 h after major abdominal surgery. We measured extravascular lung water, intrathoracic, global end-diastolic and pulmonary blood volumes, (67)Ga-transferrin pulmonary leak index and ventilatory and radiographic variables. The latter allowed computation of the lung injury score as a measure of lung injury.

RESULTS

The extravascular lung water was elevated (>7 mL kg(-1)) in 5 of 16 patients, while the pulmonary leak index was elevated in 11 patients and a supranormal extravascular lung water was associated with a high pulmonary leak index and higher extravascular lung water relative to intrathoracic blood volume or pulmonary blood volume. Patients were arbitrarily divided into those with a lung injury score >1 and < or =1, and only differed in the factors composing the score as well as in extravascular lung water divided by pulmonary blood volume. A lung injury score >1 was associated with a longer duration of mechanical ventilation.

CONCLUSION

Our data suggest that mild, subclinical, pulmonary oedema is relatively common after major vascular surgery, mainly caused by increased pulmonary capillary permeability in the absence of overt heart failure. However, permeability oedema only partially contributes to postoperative lung injury score and need for mechanical ventilation, suggesting a major contribution by atelectasis.

Effect of fluid loading with saline or colloids on pulmonary permeability, oedema and lung injury score after cardiac and major vascular surgery

BACKGROUND

The optimal type of fluid for treating hypovolaemia without evoking pulmonary oedema is still unclear, particularly in the presence of pulmonary vascular injury, as may occur after cardiac and major vascular surgery.

METHODS

In a single-centre, prospective, single-blinded clinical trial 67 mechanically ventilated patients were randomly assigned to receive saline, gelatin 4%, HES 6% or albumin 5%, according to a 90 min fluid loading protocol with target central venous pressure of 13 and pulmonary capillary wedge pressure of 15 mm Hg, within 3 h after cardiac or major vascular surgery. Before and after the protocol, we recorded haemodynamics and ventilatory variables and took chest radiographs. The pulmonary vascular injury was evaluated using the 67Ga-transferrin pulmonary leak index (PLI) and extravascular lung water (EVLW). Plasma colloid osmotic pressure (COP) was determined and the lung injury score (LIS) was calculated.

RESULTS

More saline was infused than colloid solutions (P<0.005). The COP increased in the colloid groups and decreased in patients receiving saline. Cardiac output increased more in the colloid groups. At baseline, PLI and EVLW were above normal in 60 and 30% of the patients, with no changes after fluid loading, except for a greater PLI decrease in HES than in gelatin-loaded patients. The oxygenation ratio improved in all groups. In the colloid groups, the LIS increased, because of a decrease in total respiratory compliance, probably associated with an increase in intrathoracic plasma volume.

CONCLUSIONS

Provided that fluid overloading is prevented, the type of fluid used for volume loading does not affect pulmonary permeability and oedema, in patients with acute lung injury after cardiac or major vascular surgery, except for HES that may ameliorate increased permeability. During fluid loading, changes in LIS (and respiratory compliance) do not represent changes in pulmonary permeability or oedema.

Simple vs complex radionuclide methods of assessing capillary protein permeability for diagnosing acute respiratory distress syndrome

PURPOSE

Using injection of gallium Ga 67 transferrin, technetium Tc 99m red cells, probes over the lungs, and blood samples, a pulmonary leak index (PLI) and pulmonary transcapillary escape rate (PTCER) for transferrin can be measured. This may help differentiating between cardiogenic pulmonary edema (CPE) and permeability (noncardiogenic) pulmonary edema of the acute respiratory distress syndrome (ARDS). The purpose of the study was to evaluate the relative importance of red cell labeling, blood sampling, and probe measurements in this assessment.

MATERIALS AND METHODS

Analysis of radionuclide data obtained in consecutive patients with radiographic evidence for pulmonary edema, classified as ARDS (n = 13), CPE (n = 8), or mixed (n = 5), was performed. The latter patients met ARDS criteria except for a high pulmonary capillary wedge pressure.

RESULTS

The PLI, PTCER, and the (67)Ga-lung/blood radioactivity increase (without (99m)Tc-red cell data) were specific and sensitive indices to differentiate ARDS/mixed from CPE. The blood transcapillary escape rate (TER) of (67)Ga-transferrin was about 2- to 6-fold higher in ARDS and mixed than in CPE. The TER had similar diagnostic value as the PLI, PTCER, and the (67)Ga-lung/blood radioactivity ratio increase.

CONCLUSIONS

The diagnostic value of the simple blood TER of (67)Ga-transferrin is similar to that of complex methods, using (99m)Tc-red cells and probe measurements over the lungs, because the complex methods largely depend on the blood TER. Simplification of the method without red cell labeling and probes may facilitate bedside use to diagnose permeability edema of ARDS, particularly in the absence of a pulmonary artery catheter.

Pulmonary Apoptosis After Supraceliac Aorta Clamping in a Rat Model1

BACKGROUND

Lungs are a major target in several models of systemic inflammation. We investigated the effect of gut ischemia reperfusion on lung injury as apoptotic histological changes and pulmonary dysfunction.

MATERIALS AND METHODS

Sixteen Wistar male rats were randomized in two equal groups: a control group and a gut ischemia-reperfusion (IR) group for which gut IR was performed by clamping the supraceliac aorta during 40 min. After 60 min of reperfusion, blood gas, bronchoalveolar liquid (BAL) and pulmonary tissue were sampled for measurements. Acidosis status was used to assess the importance of gut IR. Tumor necrosis factor-alpha in the BAL reflected the inflammatory pulmonary response. A terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling method was used to quantify the percentage of apoptotic cells in BAL and to visualize apoptotic cells on tissue samples. Pulmonary dysfunction was assessed by PaO(2) measure.

RESULTS

Gut IR caused an important metabolic acidosis (pH = 7.19 +/- 0.05 versus 7.32 +/- 0.02, P = 0.032 and HCO(3-) = 10.8 +/- 2.54 versus 21.1 +/- 1.72 mmol/L, P = 0.027). At the pulmonary level, there was yet no hypoxemia (paO(2) = 18.1 +/- 1.85 versus 12.3 +/- 1.1 kPa, P = 0.005) but a significant inflammatory response (tumor necrosis factor-alpha in BAL = 7.5 +/- 5 versus 0 pg/mL). The number of apoptotic cell in BAL more than doubled in the gut IR group (51.3 +/- 8 versus 23 +/- 4.3%, P = 0.046). Apoptose involved pneumocytes and bronchiolar epithelial cells.

CONCLUSIONS

Our rat models of gut IR induced a significant pulmonary injury characterized by a doubling in apoptotic cells but not yet by a functional pulmonary impairment.

Pulmonary expression of inducible heme-oxygenase after ischemia/reperfusion of the lower extremities in rats

BACKGROUND

Expression of inducible heme-oxygenase (HO-1) has been shown to be increased in various inflammatory disorders, which may confer a protective role. The aim of our study was to assess pulmonary expression of HO-1 after ischemia/reperfusion (I/R) of the lower limbs in rats.

MATERIALS AND METHODS

We compared three groups of rats (n = 5/group): one Sham group, and two I/R groups (aorta cross-clamped for 2 h followed by 2 h of reperfusion), one of which pre-treated with Zn-protoporphyrin (Zn-PP), a competitive inhibitor of HO (50 micromol/kg, i.p.). At the end of experiment, lungs were harvested for determination of HO activity and HO-1 expression by Western blot and immunohistochemistry. Lung injury was assessed by bronchoalveolar lavage, histological study, and determination of the lung Evans Blue dye content, an index of microvascular permeability.

RESULTS

I/R of the lower limbs was responsible for acute lung injury (ALI), characterized by neutrophilic infiltration (87 +/- 20 x 10(3) neutrophils/mm(3), Sham group versus 191 +/- 38 x 10(3) neutrophils/mm(3), I/R group; P < 0.002) and an increase in lung Evans blue dye content: (74 +/- 6 microg/g, Sham group versus 122 +/- 48 microg/g, I/R group; P < 0.05). Pre-treatment with Zn-PP further increases the Evans Blue content (122 +/- 48 microg/g, I/R group versus 179 +/- 23 microg/g Zn-PP group P < 0.05) and the neutrophilic infiltration. Pulmonary heme-oxygenase activity, and HO-1 content were increased after I/R. (10.5 +/- 12 pmol bilirubin/mg protein/h, Sham group versus 101.2 +/- 66 pmol bilirubin/mg protein/h, I/R group; P < 0.02). Immunohistochemistry revealed that the expression of HO-1 was mainly localized to inflammatory cells.

CONCLUSIONS

ALI following I/R of the lower limbs in rats is associated with an increase of pulmonary expression of HO-1, inhibition of this expression increase the severity of ALI.

Capillary leak syndrome in children with C4A-deficiency undergoing cardiac surgery with cardiopulmonary bypass: a double-blind, randomised controlled study

BACKGROUND

Capillary leak syndrome is a life-threatening complication after cardiopulmonary bypass (CPB), with an incidence of about 4-37% in children worldwide. On the basis of previous results, we undertook a randomised controlled study to investigate the priming with plasma rich in the C4A isotype of complement component 4 on the incidence of capillary leak syndrome in children with C4A deficiency.

METHODS

In a hospital in Wuhan, China, we randomly assigned 116 neonates, infants, and children lacking complement component C4A to receive C4A-free or C4A-rich plasma priming (n=58 each, 20 mL/kg). The primary outcome was capillary leak syndrome, identified as an increased transvascular escape rate of Evans blue dye from plasma. Concentrations of activated complement components C4 and C3, inflammatory mediators interleukin 6, interleukin 8, tumour necrosis factor (TNF) alpha, plasma protein, and PaO2/F(I)O2 ratios (ratio of the partial arterial pressure of oxygen to the fractional concentration of oxygen in inspired air) were measured before and 4 h after CPB. Analysis was by intention to treat.

FINDINGS

Three (5%) patients given C4A-rich plasma priming had capillary leak syndrome compared with 56 (97%) given C4A-free plasma (p<0.0001). At 4 h after CPB, activated C4, interleukin 6, interleukin 8, and TNFalpha concentrations were higher, whereas PaO2/F(I)O2 ratios and plasma protein concentrations were significantly lower in the C4A-free group than changes in the C4A-rich group. Activated C3 rose equally in both groups. Activated C4 significantly correlated with interleukin 6, interleukin 8, and TNFalpha concentrations; PaO2/F(I)O2 ratios; and the escape rate of Evans blue dye at 4 h after CPB. Two patients in the C4A-free group died of respiratory and renal failure on day 3 after CPB.

INTERPRETATION

In paediatric patients with C4A deficiency, C4A-rich plasma priming reduces the incidence of CPB-related capillary leak syndrome by blocking the activated C4 increase and attenuating the systemic inflammatory response after CPB.

Nitric oxide synthase inhibition: therapeutic potential in asthma

Nitric oxide (NO) is synthesized from L-arginine in the human respiratory tract by enzymes of the NO synthase (NOS) family. Levels of NO in exhaled air are increased in asthma, and measurement of exhaled NO has been advocated as a noninvasive tool to monitor the underlying inflammatory process. However, the relation of NO to disease pathophysiology is uncertain, and in particular the fundamental question of whether it should be viewed primarily as beneficial or harmful remains unanswered. Exogenously administered NO has both bronchodilator and bronchoprotective properties. Although it is unlikely that NO is an important regulator of basal airway tone, there is good evidence that endogenous NO release exerts a protective effect against various bronchoconstrictor stimuli. This response is thought to involve one or both of the constitutive NOS isoforms, endothelial NOS (eNOS) and neuronal NOS (nNOS). Therefore, inhibition of these enzymes is unlikely to be therapeutically useful in asthma and indeed may worsen disease control. On the other hand, the high concentrations of NO in asthma, which are believed to reflect upregulation of inducible NOS (iNOS) by proinflammatory cytokines, may produce various deleterious effects. These include increased vascular permeability, damage to the airway epithelium, and promotion of inflammatory cell infiltration. However, the possible effects of iNOS inhibition on allergic inflammation in asthma have not yet been described and studies in animal models have yielded inconsistent findings. Thus, the evidence to suggest that inhibition of iNOS would be a useful therapeutic strategy in asthma is limited at present. More definitive information will require studies combining agents that potently and specifically target individual NOS isoforms with direct measurement of inflammatory markers.

Respiratory function after aortic aneurysm repair: a comparison between retroperitoneal and transperitoneal approaches

OBJECTIVE

Elective abdominal aneurysm repair can be performed by using the transperitoneal or the retroperitoneal approach. The latter has been described as having a better outcome, reducing the impairment of respiratory function or the incidence of lung complications. Hence, the retroperitoneal approach has been proposed for treatment of medically high-risk patients. However, the superiority of one technique or the other in preserving pulmonary function has not been conclusively demonstrated. The aim of this study was to ascertain whether the retroperitoneal and the transperitoneal approaches affect respiratory function differently.

DESIGN

A prospective randomized study.

SETTING

Two four-bed surgical-medical ICUs of a University hospital.

PATIENTS

Twenty-three consecutive patients undergoing abdominal aortic aneurysm repair were randomized to the retroperitoneal (12 patients) and transperitoneal approach (11 patients). They were studied: a). within 30 min the end of surgery; b). 8 h after the end of surgery; and c). during a T-piece tube-weaning trial.

MEASUREMENTS

The comparison between the two groups was based on respiratory mechanics, partitioned between lung and chest wall components, basic spirometry, tension-time index of the inspiratory muscle, weaning indexes, and length of stay both in ICU and hospital.

RESULTS

The two surgical techniques do not differ in their impact on either respiratory mechanics or inspiratory muscle function or weaning indexes. However, there was a tendency for retroperitoneal patients to stay for less time both in ICU and in the hospital.

CONCLUSIONS

During the first 24 h after surgery, the postoperative impairment of respiratory function is independent of the surgical approach.

Pro- and anti-inflammatory cytokine release in open versus endovascular repair of abdominal aortic aneurysm

BACKGROUND

Pro- and anti-inflammatory cytokine release occurs with abdominal aortic aneurysm (AAA) repair although the relative contribution of each is currently poorly understood. Ischaemia-reperfusion injury is thought to play a greater role following open (OR) than endovascular (ER) repair, with resultant greater perioperative morbidity.

METHODS

Thirty-two patients undergoing OR (n = 16) and ER (n = 16) of AAA were studied. Systemic venous (SV) blood was taken at induction (baseline), 0 h (last clamp off), 4, 24, 72 and 144 h, and femoral venous (FV) blood (indwelling catheter; lower torso venous effluent) at 0, 4 and 24 h. The cytokines interleukin (IL) 6, IL-8 and IL-10 were measured in these samples.

RESULTS

In OR, SV and FV IL-6 increased from baseline to a peak at 24 h (SV 589 pg/ml (P = 0.001 versus baseline) and FV 848 pg/ml (P = 0.05)) before declining at 144 h. In ER, there was a similar pattern but the increase was smaller (24 h: SV 260 pg/ml (P = 0.003 versus baseline) and FV 319 pg/ml (P = 0.06)) at all equivalent timepoints compared with OR. IL-8 peaked earlier (4 h) from baseline in both groups before declining by 144 h, and significant differences between SV and FV were seen only in the OR group. IL-10 levels peaked in both groups at 24 h before declining at 144 h, and there were no significant locosystemic differences between the groups.

CONCLUSION

Venous pro-inflammatory cytokine changes (IL-6) are consistent with significantly greater lower-torso reperfusion injury in patients undergoing OR. Smaller responses were seen after ER (IL-6 and IL-8), although both groups showed a similar anti-inflammatory response (IL-10); this pro- and anti-inflammatory imbalance may account for the increased morbidity associated with OR.

Usefulness of pulmonary vascular leakiness assessment in interstitial pneumonitis

STUDY OBJECTIVE

Pulmonary vascular leakiness of (67)Ga-circulating transferrin in interstitial pneumonitis (IP) was estimated by our previously described method, and its ability to evaluate disease activity was compared with conventional (67)Ga scintigraphy.

DESIGN

Using 30-min dynamic scanning data after IV injection of (67)Ga citrate, the exponential equilibration coefficient of (67)Ga between the intravascular and pulmonary interstitial compartments was calculated and defined as the leak index (LI). Pulmonary (67)Ga uptake was assessed by gallium index, determined by conventional static images taken 48 h after (67)Ga citrate injection.

SETTING

Hospitalized patients.

PARTICIPANTS

The study population consisted of 17 control patients and 20 patients with IP.

RESULTS

The mean LI in patients with IP was significantly higher than in the control group (p < 0.0001), whereas no significant increase in gallium index was noted between the IP group and the control group. No significant correlation was found between gallium index and LI among all study participants. Mean LI in patients with active IP was significantly higher than in patients with stable IP (p = 0.0024).

CONCLUSIONS

An increase in pulmonary vascular leakiness was found in patients with IP. LI may be useful to assess the disease activity.

Pulmonary endothelial permeability and circulating neutrophil-endothelial markers in patients undergoing esophagogastrectomy

OBJECTIVE

Esophagogastrectomy is an established surgical treatment for esophageal malignancy. The postoperative period may be complicated by the development of acute lung injury syndromes and thus, may provide a useful model in which to study the early pathogenic mechanisms of inflammatory lung injury.

DESIGN

Open, prospective study.

SETTING

High dependency and intensive therapy units.

PATIENTS

Eight healthy male volunteers and 20 patients in the early postoperative period

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The lung protein accumulation index (PAI) of radiolabeled transferrin was determined by using a portable, double-isotope system. The following circulating inflammatory markers-thought to reflect neutrophil-endothelial activation and injury including circulating neutrophil elastase-soluble L-, E-, and P-selectins and thrombomodulin and von Willebrand factor antigen were assayed from venous blood samples The PAI for healthy volunteers was median -0.5 (range, -1.73 to 0.27) x 10(-3)/min and for patients undergoing esophagogastrectomy -0.005 (range, -1.53 to 2.28) x 10(-3)/min. There was no statistical difference between the two groups. In the postesophagogastrectomy group, a significant elevation in circulating levels of neutrophil elastase, soluble P- and E-selectin, thrombomodulin, and von Willebrand factor antigen were observed relative to the control group but only circulating plasma elastase demonstrated a significant correlation with the PAI (r2 = .23, p =.03).

CONCLUSIONS

The data suggest patients undergoing esophagogastrectomy develop a inflammatory response but this is not a surrogate of permeability and other factors are likely to determine persistent injury to the alveolar-capillary barrier function in this patient group.

Early inflammatory response after elective abdominal aortic aneurysm repair: a comparison between endovascular procedure and conventional surgery

OBJECTIVE

To determine the nature of and to compare the inflammatory responses induced by (1) endovascular and (2) conventional abdominal aortic aneurysm (AAA) repair.

MATERIAL AND METHODS

Twelve consecutive patients undergoing elective infrarenal AAA repair were prospectively studied. Seven patients were selected for endovascular procedures (the EAAA group); five patients underwent open surgery (the OAAA group). Three control patients undergoing carotid thromboendarterectomy were also included. Serial peripheral venous blood samples were collected preoperatively, immediately after declamping or placement of the endograft, and at hours 1, 3, 6, 12, 24, 48, and 72. Acute phase response expression of peripheral T lymphocyte and monocyte activation markers and adhesion molecules (flow cytometry), soluble levels of cell adhesion molecules (enzyme-linked immunosorbent assay), cytokine (tumor necrosis factor alpha, interleukin-6, and interleukin-8) release (enzyme-linked immunosorbent assay), and liberation of complement products (nephelometry) were measured.

RESULTS

Regarding acute phase response, the EAAA and OAAA groups showed significant increases in C-reactive protein (P <.001 and P =.001), body temperature (P =.035 and P =.048), and leukocyte count (P <.001 and P <.001). Similar time course patterns were observed with respect to body temperature (P =.372). Statistically significant different patterns were demonstrated for C-reactive protein (P =.032) and leukocyte count (P =.002). Regarding leukocyte activation, a significant upregulation of peripheral T lymphocyte CD38 expression was observed in the OAAA group only (P =.001). Analysis of markers such as CD69, CD40L, CD25, and CD54 revealed no perioperative fluctuations in any group. Regarding circulating cell adhesion molecules, the EAAA and OAAA groups displayed significant increases in soluble intercellular adhesion molecule-1 (P =.003 and P =.001); there was no intergroup difference (P =.193). All groups demonstrated high soluble von Willebrand factor levels (P =.018, P =. 007, and P =.027), there being no differences in the patterns (P =. 772). Otherwise, soluble vascular cell adhesion molecule-1, soluble E-selectin, and soluble P-selectin did not appear to vary in any group. Regarding cytokine release, although a tendency toward high tumor necrosis factor alpha and interleukin-8 levels was noticed in the EAAA group, global time course effects failed to reach statistical significance (P =.543 and P =.080). In contrast, interleukin-6 showed elevations in all groups (P =.058, P <.001, and P =.004). Time course patterns did not differ between the EAAA and OAAA groups (P =.840). Regarding complement activation, the C3d/C3 ratio disclosed significant postoperative elevations in the EAAA and OAAA groups (P =.013 and P =.009). This complement product release was reduced in the EAAA group (P <.001).

CONCLUSIONS

The current study indicated that both endovascular and coventional AAA repair induced significant inflammatory responses. Our findings showed that there were no large differences between the procedures with respect to circulating cell adhesion molecule and cytokine release. Moreover, the endoluminal approach produced a limited response in terms of acute phase reaction, T lymphocyte activation, and complement product liberation. This might support the concept that endovascular AAA repair represents an attractive alternative to open surgery. Given the relatively small sample size, further larger studies are required for confirmation of our observations.

Nutritional, respiratory, and psychological effects of recombinant human growth hormone in patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Recombinant human growth hormone (rhGH) has been shown to have powerful anabolic effects and to reduce or even prevent nitrogen catabolism in stressed patients. The effects of rhGH on functional parameters are less clearly defined. The aim of this study was to assess the effects of perioperative rhGH on nutritional markers, skeletal muscle function, and psychological well-being in patients undergoing infrarenal, abdominal aortic aneurysm repair.

METHODS

Thirty-three patients undergoing elective infrarenal abdominal aortic aneurysm repair were randomized to one of three groups: (1) control (n = 12): placebo for 6 days before and after surgery; (2) preop + postop (n = 10): rhGH (Genotropin; Pharmacia Ltd, Uppsala, Sweden) 0.3 IU/kg/d for 6 days before and after surgery; and (3) postop (n = 11): placebo for 6 days before and rhGH 0.3 IU/kg/d for 6 days after surgery. Patients were assessed on days -7 and -1 before surgery and days 7, 14, and 60 after surgery.

RESULTS

Administration of rhGH resulted in increased insulin-like growth factor 1 levels, the increase being significantly more marked in the group given rhGH preoperatively. Preoperative and postoperative rhGH reduced the postoperative decrease in both serum transferrin and grip strength at day 7 by 30% and 70%, respectively. Postoperative respiratory function and arterial oxygenation also were improved, with significant differences in arterial oxygenation between rhGH-treated and untreated groups. No difference in mood was seen between groups after surgery, nor was there any difference between subjective assessment of fatigue scores between groups.

CONCLUSIONS

This pilot study indicates that rhGH administered preoperatively has beneficial effects on skeletal muscle and respiratory function and may be more useful than postoperative rhGH administration alone.

Cytokine and fibrinogen response in patients undergoing open abdominal aortic aneurysm surgery

OBJECTIVES

To assess whether open abdominal aortic aneurysm (AAA) surgery influences cytokines and fibrinogen.

METHODS

Twenty-three consecutive patients operated on for AAA were compared to 11 operated controls and 20 age-matched controls. Cubital blood was sampled pre-, intra- and postoperatively and femoral blood also sampled intraoperatively.

RESULTS

Preoperatively, interleukin (Il)-6 was elevated in AAA patients. During aortic clamping, Il-6, Il-10 and monocyte chemoattractant protein-1 (MCP-1) increased significantly (p < 0.001, p < 0.01 and p < 0.05 respectively) while soluble interleukin-2 receptor (sIl-2R) and fibrinogen decreased significantly (p < 0.001 for both). After aortic declamping, Il-6, Il-10 and MCP-1 had further significant increases compared with levels during aortic clamping while sIl-2R had a further non-significant and fibrinogen a significant decrease (p < 0.05 in cubital and p < 0.001 in femoral blood). One week postoperatively Il-6, Il-10 and MCP-1 had all decreased but were still significantly elevated compared with baseline values while sIl-2R and fibrinogen showed an increase in comparison with baseline (p < 0.001 for both). Intraoperative levels of Il-6 and Il-10 showed a significant co-variation with the magnitude of operative trauma.

CONCLUSIONS

These data indicate that open AAA surgery induces a profound inflammatory and coagulative response which persists at one week postoperatively.

The 67gallium-transferrin pulmonary leak index in patients at risk for the acute respiratory distress syndrome

OBJECTIVE

To determine the occurrence and clinical importance of increased pulmonary microvascular permeability in patients at risk for acute respiratory distress syndrome (ARDS).

DESIGN

Prospective, cohort study.

SETTING

Medical and surgical intensive care unit (ICU) and department of nuclear medicine of a university hospital.

PATIENTS

Thirteen consecutive patients at risk for ARDS with sepsis (n = 4), multiple trauma (n = 3), hemorrhagic pancreatitis (n = 5), and near-drowning (n = 1), admitted into the ICU. All patients were intubated and mechanically ventilated in the course of the study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The 67gallium-transferrin pulmonary leak index (PLI) (upper limit of normal in patients scheduled for major surgery 14.7 x 10(-3)/min) was measured within 24 hrs of admission. In addition, radiographic, gas exchange, and ventilatory variables allowing calculation of the Lung Injury Score, were obtained on the day of the PLI (day 0) and from days 1 to 7. Patients were followed until discharge or death in the ICU. No patient developed ARDS (Lung Injury Score of >2.5 in the absence of congestive heart failure) and all but four patients survived. The PLI (median [range]) was 18.5 (7.0 to 81.9) x 10(-3)/min and was supranormal in 8 of 13 patients (p < .001 vs. normal). The PLI correlated with the Simplified Acute Physiology Score (SAPS) II (r[s] = .79, p < .01) and was higher in nonsurvivors than in survivors (p < .05), with a tendency for a higher SAPS II in the nonsurvivors. On day 0, the chest radiographic score of alveolar abnormalities was 0 (0 to 4), indicating absence of radiographic abnormalities in most patients. Also, on day 0, the median PaO2/FIO2 ratio was 257 (range 119 to 460). The Lung Injury Score on day 0 was 1.0 (0 to 2.0), which is consistent with mild acute lung injury in all but one patient. In the course of time, the oxygenation ratio was lower and the Lung Injury Score was higher in nonsurvivors than in survivors, particularly for the Lung Injury Score on days 1 and 2. The PLI correlated directly with the Lung Injury Score on days 0 and 1. On day 0, the PLI correlated inversely with the oxygenation ratio. On the last evaluable day of the first ICU week, the PLI correlated directly with the Lung Injury Score and the positive end-expiratory pressure level. The duration of mechanical ventilation tended to be longer in patients with a supranormal PLI.

CONCLUSIONS

In this small population, 61% of patients at risk for ARDS and with only mild respiratory changes exhibited increased microvascular permeability in the lungs at ICU admission. Increased permeability may be an early marker of acute lung injury and its clinical features, and may be associated with a relatively complicated respiratory course during the first week after admission, even in the absence of progression to ARDS. Finally, increased pulmonary microvascular permeability may be associated with severe underlying disease and ultimate mortality in the ICU.

The inflammatory response to vascular surgery-associated ischaemia and reperfusion in man: effect on postoperative pulmonary function

OBJECTIVES

To characterise the inflammatory response to vascular surgery and ischaemia/reperfusion (I/R) in man, regarding release of inflammatory mediators, recruitment and activation of neutrophils, and their relation to postoperative pulmonary function.

DESIGN

Prospective cohort study.

MATERIALS AND METHODS

Circulating neutrophil counts and plasma levels of elastase-alpha 1-antitrypsin (AT), a neutrophil degranulation product, were measured before and approx. 2.5 h (group 1, n = 19) after elective abdominal aortic surgery, and approx. 2.9 h after elective peripheral vascular surgery (group 2, n = 6), together with concentrations of neutrophil agonists, including activated complement (C3a), secretory phospholipase A2 (sPLA2), tumor necrosis factor (TNF-alpha), interleukin (IL)-6, IL-8 and granulocyte colony-stimulating factor (G-CSF). At the time of blood sampling, respiratory variables allowing computation of the lung injury score (LIS) were obtained in patients admitted after surgery in the intensive care unit (ICU), i.e. all group 1 patients and one group 2 patient.

RESULTS

Median (range) neutrophil counts rose by 80% (-28-208) and 90% (10-147) in groups 1 and 2, respectively (n.s. between groups). The increase (p < 0.05) in elastase-alpha 1-AT level was 121% (-5-439) in group 1 and 82% (18-792) in group 2 (n.s. between groups). There was a rise (p < 0.05) in C3a level by 93% (-42-751) and of sPLA2 level by 68% (-40-1400) after surgery for the groups together (n.s. between groups), and the rise of the elastase-alpha 1-AT related to that of the C3a levels. IL-6 and G-CSF concentrations increased more in group 1 than 2. The IL-8 concentration increased in group 1 only, and TNF-alpha was unchanged in all groups. In ICU patients, the LIS related to the postoperative rise in IL-6 level only, even though the rise in plasma concentrations of cytokines interrelated. No patient developed ARDS and all survived.

CONCLUSIONS

Vascular surgery and I/R in man activates complement, releases cytokines (except for TNF-alpha), and induces neutrophil recruitment and degranulation, which may primarily depend on complement activation. In contrast to the latter, the release of cytokines may depend on the extent of I/R and may contribute to transient pulmonary dysfunction after extensive I/R.

Acute lung injury after aortic surgery: the relation between lung and leg microvascular permeability to 111indium-labelled transferrin and circulating mediators

BACKGROUND

Aortic surgery is a risk factor for acute lung injury and this may relate to ischaemia/reperfusion (I/R) of the lower body and release of inflammatory mediators. The aim of this study was to define the changes in microvascular protein permeability and circulating inflammatory mediators after aortic surgery.

METHODS

In 11 consecutive patients who underwent elective aortic surgery microvascular permeability in lung and leg was measured before and a median of 2.8 hours after completion of surgery using 111indium (In)-labelled transferrin and 99mtechnetium (Tc)-labelled red blood cells, yielding a protein leak index (PLI) that is specific for protein permeability. Circulating leucocyte counts and levels of inflammatory mediators were determined.

RESULTS

In the lung the PLI rose from a median of 0.6 (range -0.5 to 2.2) x 10(-3)/min before surgery to 5.4 (-2.3 to 33.5) x 10(-3)/min after surgery, and in the leg from 0.3 (-1.6 to 1.7) x 10(-3)/min to 5.0 (1.0 to 27.8) x 10(-3)/min. The increase in PLI in the lung was related to that in the leg. Levels of activated complement C3a and tumour necrosis factor-alpha did not change, but levels of interleukin (IL)-6, IL-8 and elastase-alpha 1-antitrypsin increased. After surgery there was slight neutrophilia and the leucocyte counts were inversely related to the IL-8 level. The rise in lung but not in leg PLI was greatest in patients with the highest IL-8 levels and the lowest leucocyte counts.

CONCLUSIONS

Early after aortic surgery microvascular protein permeability increases in the leg and lung. Leg I/R injury may result in neutrophil activation and release of IL-8, which may induce neutrophil sequestration and subsequently increased pulmonary microvascular permeability. These findings may help to explain the occurrence of acute lung injury after I/R in man.

Inducible nitric oxide synthase mRNA and immunoreactivity in the lungs of rats eight hours after antigen challenge

We have previously shown that inducible nitric oxide (iNO)-synthase immunoreactivity is expressed in bronchial epithelium and increased in asthma which suggests a possible role for NO in airway hyperresponsiveness. We tested the hypothesis that exposure of a sensitized animal to antigen could account for the increased expression of iNO-synthase in the airways. We examined the expression of iNO-synthase mRNA and immunoreactivity in the lungs of ovalbumin (OA) sensitized Brown Norway (BN) rats 8 h after antigen challenge by in situ hybridization and immunocytochemistry. Sensitized and unchallenged or bovine serum albumin (BSA) challenged rats, or unsensitized and OA challenged rats served as controls. With the use of an iNO-synthase probe we found a higher expression of iNO-synthase mRNA in BN rat airways after antigen challenge with OA but not after antigen challenge with BSA or in other controls. Most of the expression was in the epithelium of the airways with few cells positive in the subepithelial inflammatory infiltrate or in lung lavage. Very strong iNO-synthase immunoreactivity was observed in the airway epithelium of sensitized and OA challenged rats. No significant immunoreactivity was observed in the inflammatory infiltrate of the airways or in lung parenchyma. In conclusion, iNO-synthase increases in the airways of sensitized rats after exposure to antigen, the major source being from airway epithelial cells. NO may have a role in the development of the late airway response and bronchial hyperresponsiveness.

Radionuclide assessment of pulmonary microvascular permeability

The literature has been reviewed to evaluate the technique and clinical value of radionuclide measurements of microvascular permeability and oedema formation in the lungs. Methodology, modelling and interpretation vary widely among studies. Nevertheless, most studies agree on the fact that the measurement of permeability via pulmonary radioactivity measurements of intravenously injected radiolabelled proteins versus that in the blood pool, the so-called pulmonary protein transport rate (PTR), can assist the clinician in discriminating between permeability oedema of the lungs associated with the adult respiratory distress syndrome (ARDS) and oedema caused by an increased filtration pressure, for instance in the course of cardiac disease, i.e. pressure-induced pulmonary oedema. Some of the techniques used to measure PTR are also able to detect subclinical forms of lung microvascular injury not yet complicated by permeability oedema. This may occur after cardiopulmonary bypass and major vascular surgery, for instance. By paralleling the clinical severity and course of the ARDS, the PTR method may also serve as a tool to evaluate new therapies for the syndrome. Taken together, the currently available radionuclide methods, which are applicable at the bedside in the intensive care unit, may provide a gold standard for detecting minor and major forms of acute microvascular lung injury, and for evaluating the severity, course and response to treatment.

The 67gallium pulmonary leak index in assessing the severity and course of the adult respiratory distress syndrome

OBJECTIVE

To establish the value of the 67Gallium (Ga) pulmonary leak index, a marker of increased permeability edema of the lungs, in assessing the severity and course of the adult respiratory distress syndrome (ARDS).

DESIGN

Prospective observational study.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Seventeen consecutive, mechanically-ventilated ARDS patients. Eleven patients (recovering from ARDS) improved, as defined by the ability to taper the level of positive end-expiratory pressure (PEEP) to 0 cm H2O at a median of 7 days after admission. Ten patients survived. Six patients did not recover and died a median of 3.5 days after admission.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The pulmonary leak index (i.e., upper limit of normal 14.1 x 10(-3)/min) was measured within 72 hrs after admission, and repeated within 48 hrs at the time of recovery in recovering patients. At admission and recovery, respiratory variables were recorded and a lung injury score was calculated. At admission, the pulmonary leak index was increased in each patient to 32.3 (range 15.6 to 52.4) and 28.7 (range 26.0 to 40.8) x 10(-3)/min in recovering and nonrecovering patients, respectively (NS). Groups did not differ with respect to the oxygenation ratio, the level of PEEP, radiographic abnormalities, and the lung injury score. At recovery, the pulmonary leak index in recovering patients had decreased in each patient and had normalized in four patients, averaging 15.2 (range 5.6 to 25.9) x 10(-3)/min, concomitantly with an increased oxygenation ratio, less radiographic abnormalities, and a decreased lung injury score (p < .01 vs. admission). For pooled recovering and nonrecovering patient data, the pulmonary leak index directly related to the lung injury score (p < .005).

CONCLUSIONS

The 67Ga pulmonary leak index may be a clinically useful tool to quantify the severity and course of ARDS, since clinical recovery from the syndrome may be characterized by amelioration of increased microvascular permeability.