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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.

BACKGROUND High-volume low-pressure (HVLP) endotracheal tube (ETT) cuffs for critically ill patients often deflate during the course of mechanical ventilation. We performed an in-vitro study to comprehensively assess HVLP cuff deflation dynamics and potential preventive measures. METHODS We evaluated 24-hour deflation of seven HVLP cuffs of cylindrical or tapered shape, and made of polyvinylchloride or polyurethane. Experiments were performed within a thermostated chamber set at 37 °C. In the first stage of experiments, the cuff pilot balloon valve was not manipulated. The cuff internal pressure was assessed hourly for 24 hours, via a linear position sensor which monitored cuff deflation displacements. Then, we re-evaluated cuff deflation of the worst-performing ETT cuffs with the cuff pilot balloon valve sealed. Finally, we inflated ETT cuffs within an artificial trachea to evaluate deflation dynamics during mechanical ventilation. RESULTS Initial tests showed an exponential decrease in cuff internal pressure in five out of seven cuffs. Cuffs of cylindrical shape and made of polyurethane demonstrated the fastest deflation rates (P

BACKGROUND: In patients on mechanical ventilation, lung hyperinflation is often performed to reverse atelectasis and clear retained mucus. We evaluated the effects of manual hyperinflation and ventilator hyperinflation on mucus clearance, gas exchange, pulmonary mechanics, and hemodynamics. METHODS: Six mechanically ventilated pigs with severe Pseudomonas aeruginosa pneumonia randomly received either 12 manual hyperinflation breaths over a period of 2 min (through a gradual manual compression of a resuscitation bag within 4 s to achieve 40 cm H2O of airway pressure), or 12 ventilator hyperinflation over 2 min to achieve the same ventilatory end points as in manual hyperinflation. Mucus clearance rate was measured through fluoroscopic tracking of tracheal markers. Prior to each maneuver and 15 min thereafter, we assessed arterial and mixed gas exchange, pulmonary mechanics, and hemodynamics. RESULTS: Both manual hyperinflation and ventilator hyperinflation significantly decreased inspiratory flow by approximately 16 L/min (P CONCLUSIONS: In an animal model of severe P. aeruginosa pneumonia, neither manual hyperinflation nor ventilator hyperinflation improved mucus clearance. If confirmed in comprehensive clinical experimentations, these findings should promote reappraisal of indications for both manual hyperinflation and ventilator hyperinflation as a therapeutic technique for mucus clearance and atelectasis reversal.

OBJECTIVES Latest trials failed to confirm merits of nebulized amikacin for critically ill patients with nosocomial pneumonia. We studied various nebulized and IV antibiotic regimens in a porcine model of severe Pseudomonas aeruginosa pneumonia, resistant to amikacin, fosfomycin, and susceptible to meropenem. DESIGN Prospective randomized animal study. SETTING Animal Research, University of Barcelona, Spain. SUBJECTS Thirty female pigs. INTERVENTIONS The animals were randomized to receive nebulized saline solution (CONTROL); nebulized amikacin every 6 hours; nebulized fosfomycin every 6 hours; IV meropenem alone every 8 hours; nebulized amikacin and fosfomycin every 6 hours; amikacin and fosfomycin every 6 hours, with IV meropenem every 8 hours. Nebulization was performed through a vibrating mesh nebulizer. The primary outcome was lung tissue bacterial concentration. Secondary outcomes were tracheal secretions P. aeruginosa concentration, clinical variables, lung histology, and development of meropenem resistance. MEASUREMENTS AND MAIN RESULTS We included five animals into each group. Lung P. aeruginosa burden varied among groups (p < 0.001). In particular, IV meropenem and amikacin and fosfomycin + IV meropenem groups presented lower P. aeruginosa concentrations versus amikacin and fosfomycin, amikacin, CONTROL, and fosfomycin groups (p < 0.05), without significant difference between these two groups undergoing IV meropenem treatment. The sole use of nebulized antibiotics resulted in dense P. aeruginosa accumulation at the edges of the interlobular septa. Amikacin, amikacin and fosfomycin, and amikacin and fosfomycin + IV meropenem effectively reduced P. aeruginosa in tracheal secretions (p < 0.001). Pathognomonic clinical variables of respiratory infection did not differ among groups. Resistance to meropenem increased in IV meropenem group versus amikacin and fosfomycin + meropenem (p = 0.004). CONCLUSIONS Our findings corroborate that amikacin and fosfomycin alone efficiently reduced P. aeruginosa in tracheal secretions, with negligible effects in pulmonary tissue. Combination of amikacin and fosfomycin with IV meropenem does not increase antipseudomonal pulmonary tissue activity, but it does reduce development of meropenem-resistant P. aeruginosa, in comparison with the sole use of IV meropenem. Our findings imply potential merits for preemptive use of nebulized antibiotics in order to reduce resistance to IV meropenem.

Background Tracheal tube biofilm develops during mechanical ventilation. We compared a novel closed-suctioning system vs standard closed-suctioning system in the prevention of tracheal tube biofilm. Methods Eighteen pigs, on mechanical ventilation for 76 h, with P. aeruginosa pneumonia were randomized to be tracheally suctioned via the KIMVENT* closed-suctioning system (control group) or a novel closed-suctioning system (treatment group), designed to remove tracheal tube biofilm through saline jets and an inflatable balloon. Upon autopsy, two tracheal tube hemi-sections were dissected for confocal and scanning electron microscopy. Biofilm area, maximal and minimal thickness were computed. Biofilm stage was assessed. Results Sixteen animals were included in the final analysis. In the treatment and control group, the mean (sd) pulmonary burden was 3.34 (1.28) and 4.17 (1.09) log cfu gr−1, respectively (P=0.18). Tracheal tube P. aeruginosa colonization was 5.6 (4.9–6.3) and 6.2 (5.6–6.9) cfu ml−1 (median and interquartile range) in the treatment and control group, respectively (P=0.23). In the treatment group, median biofilm area was 3.65 (3.22–4.21) log10 μm2 compared with 4.49 (4.27–4.52) log10 μm2 in the control group (P=0.031). In the treatment and control groups, the maximal biofilm thickness was 48.3 (26.7–71.2) µm (median and interquartile range) and 88.8 (43.8–125.7) µm, respectively. The minimal thickness in the treatment and control group was 0.6 (0–4.0) µm and 23.7 (5.3–27.8) µm (P=0.040) (P=0.017). Earlier stages of biofilm development were found in the treatment group (P Conclusions The novel CSS reduces biofilm accumulation within the tracheal tube. A clinical trial is required to confirm these findings and the impact on major outcomes.

BACKGROUND Improvements in the design of the endotracheal tube (ETT) have been achieved in recent years. We evaluated tracheal injury associated with ETTs with novel high-volume low-pressure (HVLP) cuffs and subglottic secretions aspiration (SSA) and the effects on mucociliary clearance (MCC). METHODS Twenty-nine pigs were intubated with ETTs comprising cylindrical or tapered cuffs and made of polyvinylchloride (PVC) or polyurethane. In specific ETTs, SSA was performed every 2 h. Following 76 h of mechanical ventilation, pigs were weaned and extubated. Images of the tracheal wall were recorded before intubation, at extubation, and 24 and 96 h thereafter through a fluorescence bronchoscope. We calculated the red-to-green intensity ratio (R/G), an index of tracheal injury, and the green-plus-blue (G+B) intensity, an index of normalcy, of the most injured tracheal regions. MCC was assessed through fluoroscopic tracking of radiopaque markers. After 96 h from extubation, pigs were killed, and a pathologist scored injury. RESULTS Cylindrical cuffs presented a smaller increase in R/G vs tapered cuffs (P = .011). Additionally, cuffs made of polyurethane produced a minor increase in R/G (P = .012) and less G+B intensity decline (P = .022) vs PVC cuffs. Particularly, a cuff made of polyurethane and with a smaller outer diameter outperformed all cuffs. SSA-related histologic injury ranged from cilia loss to subepithelial inflammation. MCC was 0.9 ± 1.8 and 0.4 ± 0.9 mm/min for polyurethane and PVC cuffs, respectively (P CONCLUSIONS HVLP cuffs and SSA produce tracheal injury, and the recovery is incomplete up to 96 h following extubation. Small, cylindrical-shaped cuffs made of polyurethane cause less injury. MCC decline is reduced with polyurethane cuffs.

Ventilator-associated pneumonia (VAP) is an iatrogenic pulmonary infection that develops in tracheally intubated patients on mechanical ventilation for at least 48 hours. VAP is the nosocomial infection with the greatest impact on patient outcomes and health care costs. Endogenous colonization by aerobic gram-negative pathogens, that is, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus play a pivotal role in the pathogenesis of VAP. Several preventive strategies have shown efficacy in decreasing VAP incidence and are often implemented altogether as a prevention bundle. In patients with clinical suspicion of VAP, respiratory samples should be promptly collected. The empiric treatment should be based on the local prevalence of pathogens, duration of hospital stay, and prior antimicrobial therapy. The antibiotics can be stopped or adjusted to more narrow-spectrum once cultures and susceptibilities are available.

BACKGROUND: There are few studies using animal models in chest physical therapy. However, there are no models to assess these effects in newborns. This study aimed to develop a model of obstructive atelectasis induced by artificial mucus injection in the lungs of newborn piglets, for the study of neonatal physiotherapy. METHODS: Thirteen newborn piglets received artificial mucus injection via the endotracheal tube. X-rays and blood gas analysis confirmed the atelectasis. RESULTS: The model showed consistent results between oxygenation parameters and radiological findings. Ten (76.9%) of the 13 piglets responded to the intervention. This did not significantly differ from the expected percentage of 50% by the binomial test (95% CI 46.2–95%, P = .09). CONCLUSIONS: Our model of atelectasis in newborn piglets is both feasible and appropriate to evaluate the impact of physical therapies on atelectasis in newborns.

Recomendações para a atuação do fisioterapeuta em unidade de terapia intensiva pediátrica e neonatal são fundamentais, pois esses profissionais são responsáveis pela reabilitação de pacientes graves. A reabilitação inclui desde a avaliação e prevenção de alterações cinético funcionais às intervenções de tratamento (fisioterapia respiratória e/ou motora), controle e aplicação de gases medicinais, cuidados da ventilação pulmonar mecânica invasiva e não invasiva, protocolos de desmame e extubação, insuflação traqueal de gás, protocolo de insuflação/desinsuflação do balonete intratraqueal, aplicação de surfactante, entre outros. Com o objetivo de propiciar a recuperação do doente e seu retorno às atividades funcionais. Nesse contexto, essas recomendações têm o objetivo de orientar os fisioterapeutas sobre algumas intervenções de prevenção/tratamento de fisioterapia respiratória (desobstrução das vias aéreas; reexpansão pulmonar; posicionamento no leito; aspiração das vias aéreas; inaloterapia; tosse assistida), que auxiliam no processo de reabilitação de pacientes pediátricos e neonatais em unidade de terapia intensiva em ventilação pulmonar mecânica e até 12 horas após a extubação. Developing guidelines for the role of the physiotherapist in neonatal and pediatric intensive care units is essential because these professionals are responsible for the rehabilitation of critically ill patients. Rehabilitation includes the evaluation and prevention of functional kinetic alterations, application of treatment interventions (respiratory and/or motor physiotherapy), control and application of medical gases, care of mechanical ventilation, weaning and extubation, tracheal gas insufflation, inflation/deflation of the endotracheal cuff protocol, and surfactant application, aiming to allow patients to have a full recovery and return to their functional activities. In this article, we present guidelines that are intended to guide the physiotherapist in some of the prevention/treatment interventions in respiratory therapy (airway clearance, lung expansion, position in bed, airway suction, drug inhalation, and cough assist), which help in the rehabilitation process of newborns and children in intensive care units during mechanical ventilation and up to 12 hours following extubation.

To the Editor: We read with interest the manuscript by Guimaraes et al,[1][1] who assessed in humans the pulmonary effects of manual rib cage compressions (MRCCs). The authors found a mild increase in the amount of cleared airway secretions with the use of MRCCs and no effects on respiratory