Methacholine and Ovalbumin Challenges Assessed by Forced Oscillations and Synchrotron Lung Imaging

Abstract

The pattern of lung response caused by intravenous Mch and Ova are fundamentally different. Although inhaled Mch induces a heterogeneous lung response similar to that observed with intravenous allergen, these similar patterns are due to different mechanisms.

Sevoflurane and desflurane protect cholinergic-induced bronchoconstriction of hyperreactive airways in rabbits

“…Since this adverse respiratory event is controlled by activation of the cholinergic autonomous nervous system, we applied a common stimulus, MCh, to activate the muscarinic receptors located primarily in the central airways. The magnitude and the pattern of the lung response to MCh were similar to those previously measured in naïve and sensitized animals with a similar technique, with the dominance of Raw elevations associated with parallel increases in G and minor changes in H. 5,18,25,27 The increases in Raw proved to be related to the decrease in the cross-sectional area of the central conductive airways. These changes were similarly prevented by the administration of either of these volatile anesthetics, demonstrating that these agents have a marked potential to block a central airway constriction that develops following cholinergic stimulation.…”

“…Moreover, the increases in G observed during MCh infusions with fairly constant H can be attributed to the enhanced ventilation heterogeneities that develop in the lung periphery, which was consistently confirmed in previous studies by using foreign gases and imaging techniques. 5,21 In this scenario, neither of the volatile anesthetics had a detectable effect on the elevated G. Despite the strong bronchoprotective action of these agents on the central airway tone, this finding suggests that they have no affinity to prevent a heterogeneous deterioration of the peripheral airway function. Since we observed Volatile agents and bronchoconstriction 1013 a complete recovery in all mechanical parameters following each MCh challenge, no residual effect of MCh may have biased our results.…”

“…3,4 Differences in the actions of these pathways were highlighted by demonstrating that cholinergic stimulation acting on the muscarinic receptors provokes primarily a central airway constriction, while allergen challenge induces adverse changes in the lung periphery. 5 Among the anesthetic options for the management of patients with BHR, volatile anesthetics are usually regarded as first-line drugs for maintenance of anesthesia. Extensive investigations have led to consistent conclusions on the beneficial action of sevoflurane in the prevention and/or treatment of bronchospasm by counteracting the cholinergic stimulation of the airway smooth muscle.…”

Preclinical Evaluation of 68Ga-Labeled 1,4,7-Triazacyclononane-1,4,7-Triacetic Acid-Ubiquicidin as a Radioligand for PET Infection Imaging

“…Rabbits sensitized with ovalbumin (NZR-3) will develop an early onset airway response that resembles human asthma with histopathologic changes, thus they can serve as a noninfectious model of inflammation (32). Airway and lung inflammations have been studied noninvasively, using mainly 18 F-FDG in both animals and humans (33) and other imaging techniques such as functional MRI (fMRI) (34) and fluorescencemediated tomography (FMT) (35).…”

Ventilating the Lungs Safely: What’s New for Infants and Children?

“…Some have recommended adjusting the PEEP according to the level of oxygenation, but this could be hazardous as it may require overdistension of the alveoli in order to achieve the desired oxygen level [28]. Although computed tomography (CT) has been used to objectively assess lung aeration and regional ventilation, it is not a practical bedside technique for confirming alveolar recruitment [29][30][31]. Despite these physiological considerations, the choice of the optimal PEEP in clinical pediatric practice remains hotly debated.…”