To reiterate the effects of positive pressure ventilation on right ventricular (RV) function in acute respiratory distress syndrome (ARDS), to explain in which conditions acute cor pulmonale (ACP) may worsen prognosis, and to define an approach to protection of the right ventricle.

RECENT FINDINGS: In unselected populations of ARDS patients, large studies have reported a 25% incidence of ACP. ACP has deleterious consequences, such as patent foramen ovale shunting and fewer ventilator-free days within the first 28 days. ACP may also worsen prognosis if not taken into account to adapt respiratory settings to RV function. ACP reflects the balance between lung recruitment and lung overdistension. To prevent ACP or to correct it, plateau pressure must be below 27-28 cmH2O, hypercapnia controlled, intrinsic positive end-expiratory pressure (PEEP) avoided, and a 'low' PEEP applied. Recent findings have suggested a negative correlation between the deleterious effect of PEEP on RV function and its ability to recruit the lung.

SUMMARY: Routine RV function assessment leads to an approach to mechanical ventilation in ARDS patients designed for protection of the right ventricle. This approach called 'RV protective approach' must be associated with prone positioning, a method of ventilation that improves RV function.

Aspiration is defined as the inhalation of oropharyngeal or gastric contents into the lower respiratory tract. Upon injury, epithelial cells and alveolar macrophages secrete chemical mediators, attracting and activating neutrophils, which in turn release proteases and reactive oxygen species, degrading the alveolocapillary unit.

Aspiration can lead to a range of diseases such as infectious pneumonia, chemical pneumonitis or respiratory distress syndrome with significant morbidity and mortality. It occurs in approximately 3-10 per 10 000 operations with an increased incidence in obstetric and paediatric anaesthesia. Patients are most at risk during induction of anaesthesia and extubation, in particular in emergency situations. The likelihood of significant aspiration can be reduced by fasting, pharmacological intervention and correct anaesthetic management using a rapid sequence induction. Treatment of acid aspiration is by suctioning after witnessed aspiration; antibiotics are indicated in patients with aspiration pneumonia only. Steroids are not proven to improve outcome or reduce mortality.

Patients with acute lung injury requiring mechanical ventilation should be ventilated using lung protective strategies with low tidal volumes and low plateau pressure values, attempting to limit peak lung distension and end-expiratory collapse.

TNF receptors (TNFR1 and TNFR2) and Fas belong to the system of apoptosis-signalling receptor molecules and may play a role in the pathogenesis of interstitial lung disease. Patients with cryptogenic organizing pneumonia (COP) usually respond well to corticosteroids, in contrast to those with idiopathic pulmonary fibrosis (IPF). This may be due to the different pathogenesis.

METHODS: The expression of TNFR1, TNFR2 and Fas on bronchoalveolar lavage (BAL) macrophages and lymphocytes was analysed in 9 patients with COP, 10 with IPF and 12 controls. The production of soluble TNFR1, 2 and TNF-α by alveolar macrophages was measured by ELISA.

RESULTS: TNFR1 and Fas expression on alveolar macrophages was significantly higher in COP than in controls and IPF. The expression of TNFR2 on alveolar macrophages was also increased in COP compared to controls. The expression of TNFR2 and Fas on lymphocytes was significantly higher in COP than in IPF and controls. In addition, the expression of TNFR1, TNFR2 and Fas on BAL cells correlated positively with BAL lymphocytes (p < 0.05 or p < 0.01). The production of sTNFR1 and 2 and TNF-α by macrophages in vitro was significantly increased in patients with COP compared to IPF and controls, spontaneously or with LPS stimulation (p < 0.05 or p < 0.01).There was a positive correlation between the spontaneous production of sTNFR2 and TNF-α (r = 0.494, p < 0.01).

CONCLUSIONS: This study showed an increased expression of TNF receptors and Fas on BAL cells in COP that may be indicative of the local inflammatory activity in the lung. The biologic effects of this expression needs further investigation.

The 2004 World Health Organization (WHO) classification recognizes 4 major types of lung neuroendocrine tumors: typical carcinoid, atypical carcinoid, small cell lung cancer, and large cell neuroendocrine carcinoma. Markedly different prognostic implications and treatment paradigms for these tumors underscore the importance of accurate pathologic diagnosis.