Pulmonary consequences of acute pancreatitis: critical role of the neutrophil

Predicting risk of postoperative lung injury in high-risk surgical patients: a multicenter cohort study

BACKGROUND

Acute respiratory distress syndrome (ARDS) remains a serious postoperative complication. Although ARDS prevention is a priority, the inability to identify patients at risk for ARDS remains a barrier to progress. The authors tested and refined the previously reported surgical lung injury prediction (SLIP) model in a multicenter cohort of at-risk surgical patients.

METHODS

This is a secondary analysis of a multicenter, prospective cohort investigation evaluating high-risk patients undergoing surgery. Preoperative ARDS risk factors and risk modifiers were evaluated for inclusion in a parsimonious risk-prediction model. Multiple imputation and domain analysis were used to facilitate development of a refined model, designated SLIP-2. Area under the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit test were used to assess model performance.

RESULTS

Among 1,562 at-risk patients, ARDS developed in 117 (7.5%). Nine independent predictors of ARDS were identified: sepsis, high-risk aortic vascular surgery, high-risk cardiac surgery, emergency surgery, cirrhosis, admission location other than home, increased respiratory rate (20 to 29 and ≥30 breaths/min), FIO2 greater than 35%, and SpO2 less than 95%. The original SLIP score performed poorly in this heterogeneous cohort with baseline risk factors for ARDS (area under the receiver operating characteristic curve [95% CI], 0.56 [0.50 to 0.62]). In contrast, SLIP-2 score performed well (area under the receiver operating characteristic curve [95% CI], 0.84 [0.81 to 0.88]). Internal validation indicated similar discrimination, with an area under the receiver operating characteristic curve of 0.84.

CONCLUSIONS

In this multicenter cohort of patients at risk for ARDS, the SLIP-2 score outperformed the original SLIP score. If validated in an independent sample, this tool may help identify surgical patients at high risk for ARDS.

Early identification of patients at risk of acute lung injury: evaluation of lung injury prediction score in a multicenter cohort study

RATIONALE

Accurate, early identification of patients at risk for developing acute lung injury (ALI) provides the opportunity to test and implement secondary prevention strategies.

OBJECTIVES

To determine the frequency and outcome of ALI development in patients at risk and validate a lung injury prediction score (LIPS).

METHODS

In this prospective multicenter observational cohort study, predisposing conditions and risk modifiers predictive of ALI development were identified from routine clinical data available during initial evaluation. The discrimination of the model was assessed with area under receiver operating curve (AUC). The risk of death from ALI was determined after adjustment for severity of illness and predisposing conditions.

MEASUREMENTS AND MAIN RESULTS

Twenty-two hospitals enrolled 5,584 patients at risk. ALI developed a median of 2 (interquartile range 1-4) days after initial evaluation in 377 (6.8%; 148 ALI-only, 229 adult respiratory distress syndrome) patients. The frequency of ALI varied according to predisposing conditions (from 3% in pancreatitis to 26% after smoke inhalation). LIPS discriminated patients who developed ALI from those who did not with an AUC of 0.80 (95% confidence interval, 0.78-0.82). When adjusted for severity of illness and predisposing conditions, development of ALI increased the risk of in-hospital death (odds ratio, 4.1; 95% confidence interval, 2.9-5.7).

CONCLUSIONS

ALI occurrence varies according to predisposing conditions and carries an independently poor prognosis. Using routinely available clinical data, LIPS identifies patients at high risk for ALI early in the course of their illness. This model will alert clinicians about the risk of ALI and facilitate testing and implementation of ALI prevention strategies. Clinical trial registered with www.clinicaltrials.gov (NCT00889772).

Clinical outcomes in patients with ICU-related pancreatitis

AIM: To identify risk factors predictive of intensive care unit (ICU) mortality in patients with ventilator-related pancreatitis. The clinical outcomes of patients with ventilator-related pancreatitis were compared with those of patients with pancreatitis-related respiratory failure as well as controls.

METHODS: One hundred and forty-eight patients with respiratory failure requiring mechanical ventilation and concomitant acute pancreatitis were identified from a prospectively collected dataset of 9108 consecutive patients admitted with respiratory failure over a period of five years. Sixty patients met the criteria for ventilator-related pancreatitis, and 88 (control patients), for pancreatitis-related respiratory failure.

RESULTS: Mortality rate in ventilator-related pancreatitis was comparable to that in ICU patients without pancreatitis by case-control methodology (P = 0.544). Multivariate logistic regression analysis identified low PaO₂/FiO₂ (OR: 1.032, 95% CI: 1.006-1.059, P = 0.016) as an independent risk factor for mortality in patients with ventilator-related pancreatitis. The mortality rate in patients with ventilator-related pancreatitis was lower than that in patients with acute pancreatitis-related respiratory failure (P < 0.001).

CONCLUSION: We found that low PaO₂/FiO₂ was an independent clinical parameter predictive of ICU mortality in patients with ventilator-related pancreatitis.

Sphingosine-1-phosphate and its analogue FTY720 diminish acute pulmonary injury in rats with acute necrotizing pancreatitis

OBJECTIVE

To investigate the effects of sphingosine-1-phosphate (S1P) and its analogue FTY720 on the lung injury induced by acute necrotizing pancreatitis in rats.

METHODS

Acute necrotizing pancreatitis was induced by retrogradely injection of 5% sodium taurocholate of biliopancreatic duct in rats. Sphingosine-1-phosphate (100 microg/kg) or FTY720 (1 mg/kg) was administered immediately after the model induction by peritoneal injection. Six hours after the model induction, bronchoalveolar lavage protein concentration, total cell count, polymorphonuclear neutrophil percentage, proinflammatory cytokines (interleukin 1beta, interleukin 6, and tumor necrosis factor alpha), nuclear factor kappaB activation of alveolar macrophages, and lung myeloperoxidase (MPO) activity were examined. Serum amylase and lipase were tested. In addition, histopathological changes of the pancreas and lung were observed.

RESULTS

Bronchoalveolar lavage protein concentration, total cell count, PMN percentage, proinflammatory cytokines, nuclear factor kappaB activation, lung capillary leakage, and lung myeloperoxidase were all reduced significantly in both S1P and FTY720 groups. The pulmonary pathological injury in both S1P and FTY720 groups was ameliorated obviously. Nevertheless, the serum amylase, lipase, and the pancreatic pathological damages were not decreased.

CONCLUSIONS

Sphingosine-1-phosphate and its analogue FTY720 significantly decreased pulmonary inflammation and injury in a rat model of acute lung injury caused by acute necrotizing pancreatitis and may represent a novel therapeutic strategy for the acute necrotizing pancreatitis-associated lung injury.

Noninvasive Positive Pressure Ventilation in Patients with Respiratory Failure due to Severe Acute Pancreatitis

BACKGROUND

Patients with acute pancreatitis (AP) who require mechanical ventilation have high morbidity and mortality rates. Noninvasive positive pressure ventilation (NPPV) delivered through a mask has become increasingly popular for the treatment of acute respiratory failure (ARF) and may limit some mechanical ventilation complications.

OBJECTIVES

The purpose of this retrospective, observational study was to evaluate our clinical experience with the use of NPPV in AP patients with ARF.

METHODS

From 1997 to 2003, we documented clinical data, gas exchange and outcome of the 62 AP patients admitted to our intensive care unit. Patients who benefited from NPPV (success) were compared with those who failed (intubated).

RESULTS

Twenty-nine patients were intubated at admission and 5 did not develop ARF. Of the 28 patients treated with NPPV, 15 were not intubated (54%). Both groups had a similar PaO(2)/FiO(2) ratio (142 +/- 21 vs. 133 +/- 20; p = 0.127) and severity of illness (Ranson and Balthazar scores). Presence of atelectasis, bilateral alveolar infiltrates and abdominal distension were associated with failure of NPPV. Oxygenation improved and respiratory rate decreased significantly only in the success group. Additionally, the length of stay at the intensive care unit was significantly lower in the success group.

CONCLUSION

NPPV is feasible and safe to treat ARF in selected patients with AP who require ventilatory support.

Pathophysiological aspects of severe acute pancreatitis-associated lung injury

Acute pancreatitis is an inflammatory process which occurs in severe form in 20% of all patients, out of whom 1596-25% will die. The incidence of severe acute pancreatitis-associated lung injury (APALI) varies from 15% to 55% and its severity varies from mild hypoxemia to acute respiratory distress syndrome (ARDS). Acute lung injury (ALI) and ARDS are the most significant manifestations of extra abdominal dysfunctions in severe acute pancreatitis with mortality rate as high as 60% in the first week of the onset of illness. Different pathophysiological mechanisms of severe acute pancreatitis-associated lung injury have been described. The role of enzymes, adhesion molecules, neutrophils, fibronectin and various inflammatory mediators has been emphasized. Mechanism of the acute lung injury associated with the acute pancreatitis is very complex and has not been clear yet. There is no specific therapeutic procedure and mortality rate is very high. Therefore, further studies are necessary to address this acute and growing problem in intensive medicine.

Chemokines in acute respiratory distress syndrome

A characteristic feature of all inflammatory disorders is the excessive recruitment of leukocytes to the site of inflammation. The loss of control in trafficking these cells contributes to inflammatory diseases. Leukocyte recruitment is a well-orchestrated process that includes several protein families including the large cytokine subfamily of chemotactic cytokines, the chemokines. Chemokines and their receptors are involved in the pathogenesis of several diseases. Acute lung injury that clinically manifests as acute respiratory distress syndrome (ARDS) is caused by an uncontrolled systemic inflammatory response resulting from clinical events including major surgery, trauma, multiple transfusions, severe burns, pancreatitis, and sepsis. Systemic inflammatory response syndrome involves activation of alveolar macrophages and sequestered neutrophils in the lung. The clinical hallmarks of ARDS are severe hypoxemia, diffuse bilateral pulmonary infiltrates, and normal intracardiac filling pressures. The magnitude and duration of the inflammatory process may ultimately determine the outcome in patients with ARDS. Recent evidence shows that activated leukocytes and chemokines play a key role in the pathogenesis of ARDS. The expanding number of antagonists of chemokine receptors for inflammatory disorders may hold promise for new medicines to combat ARDS.