Elevated PaCO2 levels increase pulmonary artery pressure.

Permissive hypercapnia is commonly used in mechanically ventilated patients to avoid lung injury but its effect on pulmonary artery pressure (PAP) is still unclear, particularly in combination with tidal volume (Vt). Therefore, an in vivo study was performed on adult rabbits ventilated with low (9 ml/Kg, LVt group) or high (15 ml/Kg, HVt group) tidal volume (Vt) and alterations in PAP were estimated. Both groups of animals initially were ventilated with FiO2 0.3 (Normocapnia-1) followed by inhalation of enriched CO2 gas mixture (FiCO2 0.10) to develop hypercapnia (Hypercapnia-1). After 30 min of hypercapnia, animals were re-ventilated with FiO2 0.3 to develop normocapnia (Normocapnia-2) again and then with FiCO2 0.10 to develop hypercapnia (Hypercapnia-2). Systolic, diastolic and mean PAP were assessed with a catheter in the pulmonary artery. In HP-1 and HP-2, PaCO2 increased (p < 0.0001) in both LVt and HVt animals compared to baseline values. pH decreased to ≈7.2 in HP-1 and ≈7.1 in HP -2. In normocapnia, the rise in Vt from 9 to 15 ml/Kg induced an increase in static compliance (Cstat), plateau airway pressure (Pplat) and PAP. Hypercapnia increased PAP in either LVt or HVt animals without significant effect on Cstat or Pplat. A two-way ANOVA revealed that there was not a statistically significant interaction between the effects of hypercapnia and tidal volume on mPAP (p = 0.76). In conclusion, increased Vt per se induced an increase in Cstat, Pplat and PAP in normocapnia. Hypercapnia increased PAP in rabbits ventilated with low or high Vt but this effect was not long-lasting.

Nebulised colistin for ventilator-associated pneumonia prevention.

We evaluated whether prophylactic nebulised colistin could reduce ventilator-associated pneumonia (VAP) rates in an intensive care unit (ICU) setting with prevalent multidrug-resistant (MDR) bacteria.We used a single-centre, two-arm, randomised, open-label, controlled trial in a 12-bed ICU in the University Hospital of Larissa, Greece. Patient inclusion criteria included mechanical ventilation of >48 h. The two arms consisted of prophylaxis with 500 000 U colistin (Col group) or normal saline (NS group), thrice daily, for the first 10 ICU days or until extubation. The primary outcome of the study was the 30-day VAP incidence.In total, 168 patients entered the study. VAP incidence was not different between Col and NS group patients (14 (16.7%) versus 25 (29.8%), respectively, p=0.07). Regarding the secondary outcomes, the intervention resulted in a lower VAP incidence density rate (11.4 versus 25.6, respectively, p<0.01), and less Gram-negative bacteria-VAP (p=0.03) and MDR-VAP (p=0.04). Among VAP patients (n=39), prophylaxis with inhaled colistin improved ICU survival (p=0.016). There was no evidence of increased resistance to colistin or multidrug resistance.Our findings suggest that nebulised colistin had no significant effect on VAP incidence.

Ventilator-associated tracheobronchitis increases the length of intensive care unit stay.

OBJECTIVE: To investigate prospectively the clinical course and risk factors for ventilator-associated tracheobronchitis (VAT) and the impact of VAT on intensive care unit (ICU) morbidity and mortality. DESIGN: Prospective cohort study. SETTING: University Hospital Larissa, Larissa, Greece. PATIENTS: Critical care patients who received mechanical ventilation for more than 48 hours were prospectively studied between 2009 and 2011. METHODS: The modified Clinical Pulmonary Infection Score, white blood cell count, and C-reactive protein level were systematically assessed every 2 days for the first 2 weeks of ICU stay. Bronchial secretions were assessed daily. Quantitative cultures of endotracheal secretions were performed on the first ICU day for every patient and every 2 days thereafter for the first 2 weeks or more at the discretion of the attending physicians. Definition of VAT was based on previously published criteria. RESULTS: A total of 236 patients were observed; 42 patients (18%) presented with VAT. Gram-negative pathogens, which were usually multidrug resistant, were responsible for 92.9% of cases. Patients with a neurosurgical admission presented with VAT significantly more often than did other ICU patients (28.5% vs 14.1%; . The occurrence P=.02) of VAT was a significant risk factor for increased duration of ICU stay (OR [95% CI], 3.04 [1.35­6.85]; P=.01). Age (OR [95% CI], 1.04 [1.015­1.06]; P=.02), Acute Physiology and Chronic Health Evaluation II score (OR [95% CI], 1.08 [1.015­1.16]; P=.02), and C-reactive protein level at admission (OR [95% CI], 1.05 [1.01­1.1]; P=.02) were independent factors for ICU mortality. CONCLUSIONS: VAT is a nosocomial infection that might be associated with prolonged stay in the ICU, especially in neurocritical patients. VAT was not associated with increased mortality in our study.

Inhaled antibiotics for nosocomial pneumonia.

Pneumonia, especially the more severe forms, is associated with considerable morbidity and mortality. Systemic use of antibiotics is the cornerstone of the management of pneumonia in all patients, including critical care patients. Several adjunctive strategies have been suggested to improve management. Notably, localized treatment in the lungs via the instillation or inhalation or nebulization of antibiotics may offer the theoretical advantage of a therapy which targets the lung while it has no systematic effects. However, the use of inhaled antibiotics is controversial. Methods of antibiotic delivery and microbiology vary between available studies and despite the favorable profile of this strategy, concerns have been raised by early data that this therapeutic approach may increase the appearance of resistant bacteria. In this report, we reviewed available evidence from animal and human clinical studies in respect of the role of inhaled antibiotic therapy in pneumonia. In most studies, pneumonia cure rates were found to be comparable to that of systemic antibiotic only therapy and occasionally better. Inhaled antibiotic therapy was found to have an acceptable safety profile by avoiding systemic toxicity; despite previous concerns regarding the emergence of antimicrobial resistance, recent studies did not support such concerns. However, in respect of the sparity of data larger randomized trial are needed to shed more light in this promising form of treatment.

Vibration response imaging: evaluation of rater agreement in healthy subjects and subjects with pneumonia.

BACKGROUND: We evaluated pulmonologists variability in the interpretation of Vibration response imaging (VRI) obtained from healthy subjects and patients hospitalized for community acquired pneumonia. METHODS: The present is a prospective study conducted in a tertiary university hospital. Twenty healthy subjects and twenty three pneumonia cases were included in this study. Six pulmonologists blindly analyzed images of normal subjects and pneumonia cases and evaluated different aspects of VRI images related to the quality of data acquisition, synchronization of the progression of breath sound distribution and agreement between the maximal energy frame (MEF) of VRI (which is the maximal geographical area of lung vibrations produced at maximal inspiration) and chest radiography. For qualitative assessment of VRI images, the raters' evaluations were analyzed by degree of consistency and agreement. RESULTS: The average value for overall identical evaluations of twelve features of the VRI image evaluation, ranged from 87% to 95% per rater (94% to 97% in control cases and from 79% to 93% per rater in pneumonia cases). Inter-rater median (IQR) agreement was 91% (82-96). The level of agreement according to VRI feature evaluated was in most cases over 80%; intra-class correlation (ICC) obtained by using a model of subject/rater for the averaged features was overall 0.86 (0.92 in normal and 0.73 in pneumonia cases). CONCLUSIONS: Our findings suggest good agreement in the interpretation of VRI data between different raters. In this respect, VRI might be helpful as a radiation free diagnostic tool for the management of pneumonia.