Efficacy of Telavancin in Comparison to Linezolid in a Porcine Model of Severe Methicillin-Resistant Staphylococcus aureus Pneumonia.

Current guidelines recommend vancomycin and linezolid as first-line agents against methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia. Telavancin is a potential new therapeutic alternative, specifically in monomicrobial MRSA pneumonia. This study compared the efficacies of telavancin versus linezolid in a porcine model of severe MRSA pneumonia. In 18 mechanically ventilated pigs (32.11 ± 1.18 kg), 75 ml of 106 CFU/ml of MRSA was administered into each pulmonary lobe. After the onset of pneumonia, pigs were randomized into three groups: a control group, a group receiving 22.5 mg/kg of body weight every 24 h (q24h) of telavancin, and a group receiving 10 mg/kg q12h of linezolid intravenously. Tracheal aspirate and bronchoalveolar lavage (BAL) fluids were cultured every 24 h. After 48 h of treatment, tissue samples were collected from the ventral and dorsal sections of each lobe. Microbiological and histopathological analyses were performed. Lung tissue concentrations differed among the groups (P = 0.019), with the lowest MRSA lung burden in the telavancin group (P < 0.05 versus the control). MRSA was detected in 46.7%, 40.0%, and 21.7% of the lung tissue samples from the control, linezolid, and telavancin groups, respectively (P < 0.001). MRSA concentrations differed among the groups in tracheal aspirate fluid (P = 0.011) but not in BAL fluid. Furthermore, there was no increased risk of kidney injury during telavancin use. Thus, telavancin has higher bactericidal efficacy than linezolid during the first 48 h of treatment in a porcine model of severe MRSA pneumonia. However, studies are needed to confirm the benefits of telavancin in treating MRSA nosocomial pneumonia.

Recruitment manoeuvres dislodge mucus towards the distal airways in an experimental model of severe pneumonia.

BACKGROUND: Recruitment manoeuvres generate a transient increase in trans-pulmonary pressure that could open collapsed alveoli. Recruitment manoeuvres might generate very high inspiratory airflows. We evaluated whether recruitment manoeuvres could displace respiratory secretions towards the distal airways and impair gas exchange in a porcine model of bacterial pneumonia. METHODS: We conducted a prospective randomised study in 10 mechanically ventilated pigs. Pneumonia was produced by direct intra-bronchial introduction of Pseudomonas aeruginosa. Four recruitment manoeuvres were applied randomly: extended sigh (ES), maximal recruitment strategy (MRS), sudden increase in driving pressure and PEEP (SI-PEEP), and sustained inflation (SI). Mucus transport was assessed by fluoroscopic tracking of radiopaque disks before and during each recruitment manoeuvre. The effects of each RM on gas exchange were assessed 15 min after the intervention. RESULTS: Before recruitment manoeuvres, mucus always cleared towards the glottis. Conversely, mucus was displaced towards the distal airways in 28.6% ES applications and 50% of all other recruitment manoeuvres (P=0.053). Median mucus velocity was 1.26 mm min-1 [0.48-3.89] before each recruitment manoeuvre, but was reversed (P=0.007) during ES [0.10 mm min-1 [-0.04-1.00]], MRS [0.10 mm min-1 [-0.4-0.48]], SI-PEEP [0.02 mm min-1 [-0.14-0.34]], and SI [0.10 mm min-1 [-0.63-0.75]]. When PaO2 failed to improve after recruitment manoeuvre, mucus was displaced towards the distal airways in 68.7% of the cases, compared with 31.2% recruitment manoeuvres associated with improved PaO2 (odds ratio: 4.76 (95% confidence interval: 1.13-19.97). CONCLUSIONS: Recruitment manoeuvres dislodge mucus distally, irrespective of airflow generated by different recruitment manoeuvres. Further investigation in humans is warranted to corroborate these pre clinical findings, as there may be limited benefits associated with lung recruitment in pneumonia.

In-vitro analysis of a novel 'add-on' silicone cuff to improve sealing properties of tracheal tubes.

Leakage of colonised oropharyngeal secretions across the tracheal tube cuff may cause iatrogenic pulmonary infection. We studied a novel 'add-on' cuff, which can be inserted over an existing tracheal tube and advanced into the subglottic region. The physical properties of the novel silicone cuff (BronchoGuard, Ciel Medical, USA) were evaluated in comparison with the Hi-Lo® tracheal tube. In a bench study, we identified saline inflation volumes required to transmit pressures between 15 and 30 cmH2 O against artificial tracheas of 18, 20 and 22 mm internal diameter. We computed cuff compliance, and minimal inflation volume to achieve air sealing during mechanical ventilation. Finally, we compared the leakage flow rate of artificial saliva across the novel cuff. On average, the mean (SD) inflation volumes necessary to transmit tracheal pressures of 15, 20, 25 and 30 cmH2 O were 4.1 (2.2), 4.4 (2.3), 4.6 (2.4) and 4.8 (2.4) ml for the novel cuff and 7.7 (2.5), 8.0 (2.6), 8.4 (2.6) and 8.7 (2.7) ml for the Hi-Lo tube, respectively (p < 0.001). The minimal inflation volumes to achieve air sealing were 3.8 (0.9) and 10.5 (2.1) ml (p < 0.001), which resulted in transmitted tracheal pressures of 8.3 (9.8) and 27.6 (34.8) cmH2 O (p < 0.001). Compliance was 0.026 (0.004) and 0.616 (0.324) ml.cmH2 0-1 , respectively (p < 0.001). Although massive leak was found when the novel cuff transmitted pressures ≤ 20 cmH2 O against the trachea, leakage was avoided with pressures ≥ 25 cmH2 O, owing to optimal contact between the cuff and the tracheal wall. In contrast, the standard cuff consistently leaked irrespective of the pressure. We conclude that the novel cuff has advantageous properties that warrant clinical corroboration.

Genetic variants identified in novel candidate genes for anorexia nervosa and analysis of molecular pathways for diagnostic applications.

OBJECTIVE: Anorexia nervosa (AN) is a severe psychiatric disorder characterized by an intense fear of gaining weight, a relentless pursuit of thinness, and a distorted body image. Recent research highlights the substantial contribution of genetics to AN's etiology, with genes like BDNF, SLC6A4, and DRD2 implicated. However, a comprehensive genetic test for AN diagnosis is lacking. This study aims to elucidate the biological foundations of AN, examining variants in genes associated with syndromic forms, rare variants in AN patients, and candidate genes from GWAS studies, murine models, or established molecular pathways. MATERIALS AND METHODS: The study involved 135 AN patients from Italy, diagnosed based on DSM-V criteria. A specialized Next-Generation Sequencing panel targeting 163 genes was designed. Sequencing was performed on an Illumina MiSeq System, and variants were analyzed using bioinformatics tools. Data on clinical parameters, exercise habits, and AN types were collected. RESULTS: The AN cohort, predominantly female, exhibited diverse clinical characteristics. Our analysis identified gene variants associated with syndromic forms of AN, such as STRA6, NF1, MAT1A, and ABCC6. Variants were also found in known AN-related genes (CD36, DRD4, GCKR, GHRL, GRIN3B, GPR55, LEPR) and in other 16 candidate genes (A2M, AEBP1, ABHD4, ACBD7, CNTNAP, GFRAL, GRIN2D, LIPE, LMNA, NMU, PDE3B, POMC, RYR1, TNXB, TYK2, VPS13B), highlighting the complexity of AN's genetic landscape. The endocannabinoid and dopamine pathways play crucial roles. Skeletal muscle-related genes and appetite-regulating hormones also revealed potential connections. Adipogenesis-related genes suggest AN's association with subcutaneous adipose tissue deficiency. CONCLUSIONS: This study provides comprehensive insights into the genetic underpinnings of AN, emphasizing the importance of multiple pathways. The identified variants contribute.

Does high PEEP prevent alveolar cycling?

Acute respiratory distress syndrome (ARDS) patients need mechanical ventilation to sustain gas exchange. Animal experiments showed that mechanical ventilation with high volume/plateau pressure and no positive end-expiratory pressure (PEEP) damages healthy lungs, while low tidal volumes and the application of higher PEEP levels are protective. PEEP makes the lung homogeneous, reducing the pressure multiplication at the interface between lung units with different inflation statuses and keeps the lung open through the whole respiratory cycle, avoiding intratidal opening and closing. Four randomized clinical trials tested a higher PEEP strategy compared to a lower PEEP strategy but failed to show any survival benefit. These results, which apparently contradict preclinical data, may be explained by CT scanning, which investigates the behaviour of ARDS lung upon inflation and deflation demonstrating that: (1) 15 cmH2O PEEP is insufficient to overcome the closing pressures of the lung and keep it open through the whole respiratory cycle; (2) lung recruitment is continuous along the volume-pressure curve. The application of a PEEP level around 15 cmH2O does not abolish opening and closing, but the lung region undergoing opening and closing is simply shifted downward, i. e. becomes more vertebral in the supine patient. (3) Recruited lung tissue becomes poorly inflated and not well inflated; poorly inflated tissue is inhomogeneous: while increasing PEEP the reduction in lung inhomogeneity is small or non-existent.

Ventilator-related causes of lung injury: the mechanical power.

PURPOSE: We hypothesized that the ventilator-related causes of lung injury may be unified in a single variable: the mechanical power. We assessed whether the mechanical power measured by the pressure-volume loops can be computed from its components: tidal volume (TV)/driving pressure (∆P aw), flow, positive end-expiratory pressure (PEEP), and respiratory rate (RR). If so, the relative contributions of each variable to the mechanical power can be estimated. METHODS: We computed the mechanical power by multiplying each component of the equation of motion by the variation of volume and RR: [Formula: see text]where ∆V is the tidal volume, ELrs is the elastance of the respiratory system, I:E is the inspiratory-to-expiratory time ratio, and R aw is the airway resistance. In 30 patients with normal lungs and in 50 ARDS patients, mechanical power was computed via the power equation and measured from the dynamic pressure-volume curve at 5 and 15 cmH2O PEEP and 6, 8, 10, and 12 ml/kg TV. We then computed the effects of the individual component variables on the mechanical power. RESULTS: Computed and measured mechanical powers were similar at 5 and 15 cmH2O PEEP both in normal subjects and in ARDS patients (slopes = 0.96, 1.06, 1.01, 1.12 respectively, R (2) > 0.96 and p < 0.0001 for all). The mechanical power increases exponentially with TV, ∆P aw, and flow (exponent = 2) as well as with RR (exponent = 1.4) and linearly with PEEP. CONCLUSIONS: The mechanical power equation may help estimate the contribution of the different ventilator-related causes of lung injury and of their variations. The equation can be easily implemented in every ventilator's software.