[Lung protective ventilation in ARDS]

Hyaluronic acid plasma levels during high versus low tidal volume ventilation in a porcine sepsis model

Background

Shedding of the endothelial glycocalyx can be observed regularly during sepsis. Moreover, sepsis may be associated with acute respiratory distress syndrome (ARDS), which requires lung protective ventilation with the two cornerstones of application of low tidal volume and positive end-expiratory pressure. This study investigated the effect of a lung protective ventilation on the integrity of the endothelial glycocalyx in comparison to a high tidal volume ventilation mode in a porcine model of sepsis-induced ARDS.

Methods

After approval by the State and Institutional Animal Care Committee, 20 male pigs were anesthetized and received a continuous infusion of lipopolysaccharide to induce septic shock. The animals were randomly assigned to either low tidal volume ventilation, high tidal volume ventilation, or no-LPS-group groups and observed for 6 h. In addition to the gas exchange parameters and hematologic analyses, the serum hyaluronic acid concentrations were determined from central venous blood and from pre- and postpulmonary and pre- and postcerebral circulation. Post-mortem analysis included histopathological evaluation and determination of the pulmonary and cerebral wet-to-dry ratios.

Results

Both sepsis groups developed ARDS within 6 h of the experiment and showed significantly increased serum levels of hyaluronic acid in comparison to the no-LPS-group. No significant differences in the hyaluronic acid concentrations were detected before and after pulmonary and cerebral circulation. There was also no significant difference in the serum hyaluronic acid concentrations between the two sepsis groups. Post-mortem analysis showed no significant difference between the two sepsis groups.

Conclusion

In a porcine model of septic shock and ARDS, the serum hyaluronic acid levels were significantly elevated in both sepsis groups in comparison to the no-LPS-group. Intergroup comparison between lung protective ventilated and high tidal ventilated animals revealed no significant differences in the serum hyaluronic acid levels.

Lung protective ventilation and hospital survival of cardiac intensive care patients

OBJECTIVE

To detect connections between parameters of ventilation and outcomes of cardiac intensive care patients.

DESIGN AND SETTING

Noninterventional study. Between 05/11 and 05/12 all patients with acute heart failure and post cardiopulmonary resuscitation were registered. Lung protective ventilation was defined as peak inspiratory pressure (PIP) < 30 mmHg and tidal volume (Vt) < = 6 ml/kg.

RESULTS

In total, 129 patients were included in the study, 68.2 % male, age 67.9 ± 13.4 years, weight 71.4 ± 37.2 kg, predictive body weight 66.9 ± 8.8 kg, mortality 47.3 %. Lung protective ventilated patients at day 1: 17.3 % with a significant difference between surviving and nonsurviving patients (24.1 % vs. 9.6 %; p < 0.05). Logistic regression models showed a strong connection between PIP and survival (odds ratio 1.13; p < 0.05). Vt showed no significant influence on survival.

CONCLUSION

Our data recommends a strict observance of a low PIP for cardiac intensive care patients, whereas Vt seems to be of secondary importance.

[Acute on chronic respiratory failure in interstitial pneumonias]

BACKGROUND

Acute exacerbations of idiopathic interstitial pneumonias and exacerbations of pleuropulmonary disease in connective tissue diseases are associated with a high mortality.

DIAGNOSTIC PROCEDURES

They have to be differentiated from respiratory failure in patients with interstitial lung disease as a result of infections, pulmonary embolism, cardiac failure and drug toxicity, because the latter can be treated causally. The extent and the invasivity of diagnostic procedures have to be adopted to the patient's situation. A rapid diagnosis is important in order to initiate therapies (antibiotics, anticoagulation, immunosuppression) in treatable causes of exacerbations.

IMPORTANCE OF VENTILATION

The prognosis for patients who are under invasive mechanical ventilation in acute exacerbations of interstitial lung disease is poor. Especially in acute exacerbations of idiopathic pulmonary fibrosis (IPF), there is no general recommendation for either invasive or for noninvasive ventilation. In acute exacerbations of other subtypes of interstitial pneumonia, either idiopathic or as a pulmonary manifestation of connective tissue disease, and in all secondary exacerbations of idiopathic interstitial pneumonias which offer further treatment options, the decision about mechanical ventilation requires a differentiated assessment.

LUNG TRANSPLANTATION

In younger patients with interstitial lung disease and a progressive disease, indication for lung transplantation should be made early and before an exacerbation. If patients listed for lung transplantation experience an acute exacerbation, bridging-to-transplant has to be discussed with the transplant unit. In cases without further causal treatment options palliative care must be initiated.