The Effects of Prone with Respect to Supine Position on Stress Relaxation, Respiratory Mechanics, and the Work of Breathing Measured by the End-Inflation Occlusion Method in the Rat

A zwitterionic chromophore as both a biomarker-activatable optical imaging probe and a therapeutic agent for the detection and treatment of acute lung injury with bacterial infection

Acute lung injury (ALI), often complicated by bacterial infection, poses significant challenges in diagnosis and treatment. Nitric oxide (NO) plays a key role in the pathophysiology of ALI, making it an ideal biomarker for early detection. In this study, we developed a zwitterionic chromophore, ZW-N, designed as both a biomarker-activatable imaging probe and a therapeutic agent for ALI with bacterial infection. The chromophore ZW-N integrates quaternary ammonium groups for antimicrobial activity and zwitterionic sulfonate groups to enhance biocompatibility and water solubility. Built on a flexible propanyl linker that couples two heptamethine cyanine dyes, ZW-N enables biomarker-responsive dual-modal imaging via optoacoustic (OA) imaging and near-infrared second-window (NIR-II) fluorescence imaging. Moreover, the chromophore ZW-N demonstrates therapeutic efficacy when combined with the clinically used antioxidant N-acetylcysteine (NAC) to treat ALI with bacterial infection. This dual-functional chromophore offers a promising platform for non-invasive, real-time monitoring of ALI, providing significant potential for improved detection and a more effective treatment strategy.

Can postural changes in spirometry in children with Duchenne muscular dystrophy predict sleep hypoventilation?

AIM

To explore the relationship between postural changes in lung function and polysomnography (PSG) in children with Duchenne muscular dystrophy (DMD).

METHODS

In this prospective cross-sectional study, children with DMD performed spirometry in sitting and supine positions. A control group of age and gender matched healthy children also underwent postural lung function testing. PSG was performed within six months of spirometry.

RESULTS

Seventeen children with DMD, aged 12.3 ± 3 years performed sitting spirometry. 14 (84%) performed acceptable spirometry in the supine position. Mean FEV1sit and FVCsit were 77% (SD ± 22) and 74% (SD ± 20.4) respectively, with mean% ΔFVC(sit-sup) 9% (SD ± 11) (range 2% to 20%), and was significantly greater than healthy controls 4% (n = 30, SD ± 3, P < 0.001). PSG data on the 14 DMD children with acceptable supine spirometry showed total AHI 6.9 ± 5.9/hour (0.3 to 29), obstructive AHI 5.2 ± 4.0/hour (0.2 to 10), and REM AHI 14.1 ± -5.3/hour (0.1 to 34.7). ΔFVC(sit-sup) had poor correlation with hypoventilation on polysomnography.

CONCLUSION

Children with DMD and mild restrictive lung disease showed greater postural changes in spirometry than healthy controls but lower supine spirometry was not predictive of sleep hypoventilation.

Regional lung viscoelastic properties in supine and prone position in a porcine model of acute respiratory distress syndrome

Regional viscoelastic properties of thoracic tissues in acute respiratory distress syndrome (ARDS) and their change with position and positive end-expiratory pressure (PEEP) are unknown. In an experimental porcine ARDS, dorsal and ventral lung (R₂,L and E₂,L) and chest wall (R₂,cw and E₂,cw) viscoelastic resistive (R) and elastic (E) parameters were measured at 20, 15, 10, and 5 cmH₂O PEEP in supine and prone position. E₂ and R₂ were obtained by fitting the decay of pressure after end-inspiratory occlusion to the equation: P_viscmax (t) =R₂ e^-t/τ₂, where t is the length of occlusion and τ₂ time constant. E₂ was equal to R₂/τ₂. R₂,cw and E₂,cw were measured from esophageal, dorsal, and ventral pleural pressures. Global R₂,L and E₂,L were obtained from the global transpulmonary pressure (airway pressure-esophageal pressure), and regional R₂,L and E₂,L from the dorsal and ventral airway pressure-pleural pressure difference. Lung ventilation was measured by electrical impedance tomography (EIT). Global R₂,cw and E₂,cw did not change with PEEP or position. Global R₂,L [median(Q1-Q3)] was 37.1 (11.0-65.1), 5.1 (4.3-5.5), 12.1 (8.4-19.5), and 41.0 (26.6-53.5) cmH₂O/L/s in supine, and 15.3 (9.1-41.9), 7.9 (5.7-11.0), 8.0 (5.1-12.1), and 12.9 (6.4-19.4) cmH₂O/L in prone from 20 to 5 cmH₂O PEEP (P = 0.06 for PEEP and P = 0.06 for position). Dorsal R₂,L significantly and positively correlated with the amount of collapse measured with EIT. Global and regional lung and chest wall viscoelastic parameters can be described by a simple rheological model. Regional E₂ and R₂ were uninfluenced by PEEP and position except for PEEP on dorsal E₂,L and position on dorsal E₂,cw.NEW & NOTEWORTHY In a porcine model of acute respiratory distress syndrome, data were successfully fitted to a rheological model of the nonlinear behavior of viscoelastic properties of lung and chest wall at different positive end-expiratory pressure (PEEP) in the supine and prone position. Prone position tended to decrease lung viscoelastic resistive component. PEEP had a significant effect on dorsal lung viscoelastic elastance. Finally, lung viscoelastic resistance correlated with the amount of lung collapse assessed by electrical impedance tomography.

The effects of nifedipine on respiratory mechanics investigated by theend-inflation occlusion method in the rat

CONTEXT

Calcium channel blockers may theoretically exhibit relaxing effects not only on vascular smooth muscle but also on airway smooth muscle.

OBJECTIVE

To investigate possible effects of nifedipine on respiratory mechanics in the rat.

METHODS

Respiratory system mechanical parameters were measured by the end-inflation occlusion method in the rat in vivo before and after the intraperitoneal administration of nifedipine.

RESULTS

We found that nifedipine affects respiratory mechanics, inducing a reduction of airway resistance and of respiratory system elastance, probably because of a relaxing action on airway and parenchimal smooth muscle cells.

CONCLUSION

Should these results be further confirmed by human investigations, a possible role of nifedipine in pharmacological respiratory system's diseases treatment may be suggested.