Evaluating Airway Management in Patients With Trisomy 21 in the PICU and Cardiac ICU: A Retrospective Cohort Study.

OBJECTIVES: Children with trisomy 21 often have anatomic and physiologic features that may complicate tracheal intubation (TI). TI in critically ill children with trisomy 21 is not well described. We hypothesize that in children with trisomy 21, TI is associated with greater odds of adverse airway outcomes (AAOs), including TI-associated events (TIAEs), and peri-intubation hypoxemia (defined as > 20% decrease in pulse oximetry saturation [Sp o2 ]). DESIGN: Retrospective database study using the National Emergency Airway Registry for Children (NEAR4KIDS). SETTING: Registry data from 16 North American PICUs and cardiac ICUs (CICUs), from January 2014 to December 2020. PATIENTS: A cohort of children under 18 years old who underwent TI in the PICU or CICU from in a NEAR4KIDS center. We identified patients with trisomy 21 and selected matched cohorts within the registry. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We included 8401 TIs in the registry dataset. Children with trisomy 21 accounted for 274 (3.3%) TIs. Among those with trisomy 21, 84% had congenital heart disease and 4% had atlantoaxial instability. Cervical spine protection was used in 6%. The diagnosis of trisomy 21 (vs. without) was associated with lower median weight 7.8 (interquartile range [IQR] 4.5-14.7) kg versus 10.6 (IQR 5.2-25) kg ( p < 0.001), and more higher percentage undergoing TI for oxygenation (46% vs. 32%, p < 0.001) and ventilation failure (41% vs. 35%, p = 0.04). Trisomy 21 patients had more difficult airway features (35% vs. 25%, p = 0.001), including upper airway obstruction (14% vs. 8%, p = 0.001). In addition, a greater percentage of trisomy 21 patients received atropine (34% vs. 26%, p = 0.004); and, lower percentage were intubated with video laryngoscopy (30% vs. 37%, p = 0.023). After 1:10 (trisomy 21:controls) propensity-score matching, we failed to identify an association difference in AAO rates (absolute risk difference -0.6% [95% CI -6.1 to 4.9], p = 0.822). CONCLUSIONS: Despite differences in airway risks and TI approaches, we have not identified an association between the diagnosis of trisomy 21 and higher AAOs.

Particle-Tracking Microrheology Using Micro-Optical Coherence Tomography.

Clinical manifestations of cystic fibrosis (CF) result from an increase in the viscosity of the mucus secreted by epithelial cells that line the airways. Particle-tracking microrheology (PTM) is a widely accepted means of determining the viscoelastic properties of CF mucus, providing an improved understanding of this disease as well as an avenue to assess the efficacies of pharmacologic therapies aimed at decreasing mucus viscosity. Among its advantages, PTM allows the measurement of small volumes, which was recently utilized for an in situ study of CF mucus formed by airway cell cultures. Typically, particle tracks are obtained from fluorescence microscopy video images, although this limits one's ability to distinguish particles by depth in a heterogeneous environment. Here, by performing PTM with high-resolution micro-optical coherence tomography (µOCT), we were able to characterize the viscoelastic properties of mucus, which enables simultaneous measurement of rheology with mucociliary transport parameters that we previously determined using µOCT. We obtained an accurate characterization of dextran solutions and observed a statistically significant difference in the viscosities of mucus secreted by normal and CF human airway cell cultures. We further characterized the effects of noise and imaging parameters on the sensitivity of µOCT-PTM by performing theoretical and numerical analyses, which show that our system can accurately quantify viscosities over the range that is characteristic of CF mucus. As a sensitive rheometry technique that requires very small fluid quantities, µOCT-PTM could also be generally applied to interrogate the viscosity of biological media such as blood or the vitreous humor of the eye in situ.

Low coherence interferometry approach for aiding fine needle aspiration biopsies.

We present portable preclinical low-coherence interference (LCI) instrumentation for aiding fine needle aspiration biopsies featuring the second-generation LCI-based biopsy probe and an improved scoring algorithm for tissue differentiation. Our instrument and algorithm were tested on 38 mice with cultured tumor mass and we show the specificity, sensitivity, and positive predictive value of tumor detection of over 0.89, 0.88, and 0.96, respectively.

A functional anatomic defect of the cystic fibrosis airway.

RATIONALE: The mechanisms underlying cystic fibrosis (CF) lung disease pathogenesis are unknown. OBJECTIVES: To establish mechanisms linking anion transport with the functional microanatomy, we evaluated normal and CF piglet trachea as well as adult swine trachea in the presence of selective anion inhibitors. METHODS: We investigated airway functional microanatomy using microoptical coherence tomography, a new imaging modality that concurrently quantifies multiple functional parameters of airway epithelium in a colocalized fashion. MEASUREMENTS AND MAIN RESULTS: Tracheal explants from wild-type swine demonstrated a direct link between periciliary liquid (PCL) hydration and mucociliary transport (MCT) rates, a relationship frequently invoked but never experimentally confirmed. However, in CF airways this relationship was completely disrupted, with greater PCL depths associated with slowest transport rates. This disrupted relationship was recapitulated by selectively inhibiting bicarbonate transport in vitro and ex vivo. CF mucus exhibited increased viscosity in situ due to the absence of bicarbonate transport, explaining defective MCT that occurs even in the presence of adequate PCL hydration. CONCLUSIONS: An inherent defect in CF airway surface liquid contributes to delayed MCT beyond that caused by airway dehydration alone and identifies a fundamental mechanism underlying the pathogenesis of CF lung disease in the absence of antecedent infection or inflammation.

An autoregulatory mechanism governing mucociliary transport is sensitive to mucus load.

Mucociliary clearance, characterized by mucus secretion and its conveyance by ciliary action, is a fundamental physiological process that plays an important role in host defense. Although it is known that ciliary activity changes with chemical and mechanical stimuli, the autoregulatory mechanisms that govern ciliary activity and mucus transport in response to normal and pathophysiological variations in mucus are not clear. We have developed a high-speed, 1-µm-resolution, cross-sectional imaging modality, termed micro-optical coherence tomography (µOCT), which provides the first integrated view of the functional microanatomy of the epithelial surface. We monitored invasion of the periciliary liquid (PCL) layer by mucus in fully differentiated human bronchial epithelial cultures and full thickness swine trachea using µOCT. We further monitored mucociliary transport (MCT) and intracellular calcium concentration simultaneously during invasion of the PCL layer by mucus using colocalized µOCT and confocal fluorescence microscopy in cell cultures. Ciliary beating and mucus transport are up-regulated via a calcium-dependent pathway when mucus causes a reduction in the PCL layer and cilia height. When the load exceeds a physiological limit of approximately 2 µm, this gravity-independent autoregulatory mechanism can no longer compensate, resulting in diminished ciliary motion and abrogation of stimulated MCT. A fundamental integrated mechanism with specific operating limits governs MCT in the lung and fails when periciliary layer compression and mucus viscosity exceeds normal physiologic limits.

Spectrally encoded confocal microscopy of esophageal tissues at 100 kHz line rate.

Spectrally encoded confocal microscopy (SECM) is a reflectance confocal microscopy technology that uses a diffraction grating to illuminate different locations on the sample with distinct wavelengths. SECM can obtain line images without any beam scanning devices, which opens up the possibility of high-speed imaging with relatively simple probe optics. This feature makes SECM a promising technology for rapid endoscopic imaging of internal organs, such as the esophagus, at microscopic resolution. SECM imaging of the esophagus has been previously demonstrated at relatively low line rates (5 kHz). In this paper, we demonstrate SECM imaging of large regions of esophageal tissues at a high line imaging rate of 100 kHz. The SECM system comprises a wavelength-swept source with a fast sweep rate (100 kHz), high output power (80 mW), and a detector unit with a large bandwidth (100 MHz). The sensitivity of the 100-kHz SECM system was measured to be 60 dB and the transverse resolution was 1.6 µm. Excised swine and human esophageal tissues were imaged with the 100-kHz SECM system at a rate of 6.6 mm(2)/sec. Architectural and cellular features of esophageal tissues could be clearly visualized in the SECM images, including papillae, glands, and nuclei. These results demonstrate that large-area SECM imaging of esophageal tissues can be successfully conducted at a high line imaging rate of 100 kHz, which will enable whole-organ SECM imaging in vivo.

Method for quantitative study of airway functional microanatomy using micro-optical coherence tomography.

We demonstrate the use of a high resolution form of optical coherence tomography, termed micro-OCT (µOCT), for investigating the functional microanatomy of airway epithelia. µOCT captures several key parameters governing the function of the airway surface (airway surface liquid depth, periciliary liquid depth, ciliary function including beat frequency, and mucociliary transport rate) from the same series of images and without exogenous particles or labels, enabling non-invasive study of dynamic phenomena. Additionally, the high resolution of µOCT reveals distinguishable phases of the ciliary stroke pattern and glandular extrusion. Images and functional measurements from primary human bronchial epithelial cell cultures and excised tissue are presented and compared with measurements using existing gold standard methods. Active secretion from mucus glands in tissue, a key parameter of epithelial function, was also observed and quantified.

Genomic analyses of aminergic signaling systems (dopamine, octopamine and serotonin) in Daphnia pulex.

Amines are one class of signaling molecules used by nervous systems. In crustaceans, four amines are recognized: dopamine, histamine, octopamine, and serotonin. While much is known about the physiological actions of amines in crustaceans, little is known about them at the molecular level. Recently, we mined the Daphnia pulex genome for proteins required for histaminergic signaling. Here, we expand this investigation, mining the D. pulex genome for proteins necessary for dopamine, octopamine and serotonin signaling. Using known Drosophila protein sequences, the D. pulex database was queried for genes encoding homologs of amine biosynthetic enzymes, receptors and transporters. Among the proteins identified were the biosynthetic enzymes tryptophan-phenylalanine hydroxylase (dopamine, octopamine and serotonin), tyrosine hydroxylase (dopamine), DOPA decarboxylase (dopamine and serotonin), tyrosine decarboxylase (octopamine), tyramine ß-hydroxylase (octopamine) and tryptophan hydroxylase (serotonin), as well as receptors for each amine and several amine transporters (dopamine and serotonin). Comparisons of the Daphnia proteins with their Drosophila queries showed high sequence identity/similarity, particularly in domains required for function. The data presented in this study provide the first molecular descriptions of dopamine, octopamine and serotonin signaling systems in Daphnia, and provide foundations for future molecular, biochemical, anatomical, and physiological investigations of aminergic signaling in this species.