Clinical Response to Third-Line Angiotensin-II vs Epinephrine in Septic Shock: A Propensity-Matched Cohort Study.

BACKGROUND: The appropriate third-line vasopressor in septic shock patients receiving norepinephrine and vasopressin is unknown. Angiotensin-II (AT-II) offers a unique mechanism of action to traditionally used vasopressors in septic shock. OBJECTIVE: The objective of this study was to compare the clinical efficacy and safety of third-line AT-II to epinephrine in patients with septic shock. METHODS: A single-center, retrospective cohort study of critically ill patients was performed between April 1, 2019 and July 31, 2022. Propensity-matched (2:1) analysis compared adults with septic shock who received third-line AT-II to controls who received epinephrine following norepinephrine and vasopressin. The primary outcome was clinical response 24 hours after third-line vasopressor initiation. Additional efficacy and safety outcomes were investigated. RESULTS: Twenty-three AT-II patients were compared with 46 epinephrine patients. 47.8% of AT-II patients observed a clinical response at hour 24 compared with 28.3% of epinephrine patients (P = 0.12). In-hospital mortality (65.2% vs 73.9%, P = 0.45), cardiac arrhythmias (26.1% vs 26.1%, P = 0.21), and thromboembolism (4.3% vs 2.2%, P = 0.61) were not observed to be statistically different between groups. CONCLUSIONS AND RELEVANCE: Administration of AT-II as a third-line vasopressor agent in septic shock patients was not associated with significantly improved clinical response at hour 24 compared with epinephrine. Although underpowered to detect meaningful differences, the clinical observations of this study warrant consideration and further investigation of AT-II as a third-line vasopressor in septic shock.

Effect of Early Administration of Vasopressin on New-Onset Arrhythmia Development in Patients With Septic Shock: A Retrospective, Observational Cohort Study.

Background: Adjunctive vasopressin use in septic shock reduces catecholamine requirements and is associated with a lower incidence of new-onset arrhythmias (NOAs). The association of vasopressin timing on NOA development is ill-described. Objective: To determine whether early administration of vasopressin was associated with a lower incidence of NOA in septic shock patients. Methods: A retrospective analysis of intensive care unit (ICU) patients at a large, academic medical center. Septic shock patients who required vasopressin and norepinephrine were eligible for inclusion. Patients were excluded for receipt of other vasoactive agents, history of cardiac arrhythmias, or outside hospital admission. Early vasopressin was defined as receipt within 6 hours of septic shock onset. The primary outcome was incidence of NOA. Results: In total, 436 patients, 220 (50.4%) in the early and 216 (49.6%) in the late vasopressin group, were included. Early vasopressin was not associated with a lower incidence of NOA compared with late vasopressin (9% vs 7%, median absolute difference [95% confidence interval, CI]: -2.1 [-7.2, 3.0], P = 0.41). Early vasopressin patients were observed to have shorter shock duration (2 vs 4 days, median absolute difference [95% CI]: 2 [1, 2], P < 0.001), and ICU length of stay (6 vs 7 days, median absolute difference [95% CI]: 1 [0, 2], P = 0.02). Conclusions and Relevance: Early vasopressin use was not associated with a lower incidence of NOA. Additional studies are needed to elucidate the effect of vasopressin timing on NOA and other clinical outcomes.

Early development of respiratory motor circuits in larval zebrafish (Danio rerio).

Rhythm-generating circuits in the vertebrate hindbrain form synaptic connections with cranial and spinal motor neurons, to generate coordinated, patterned respiratory behaviors. Zebrafish provide a uniquely tractable model system to investigate the earliest stages in respiratory motor circuit development in vivo. In larval zebrafish, respiratory behaviors are carried out by muscles innervated by cranial motor neurons-including the facial branchiomotor neurons (FBMNs), which innervate muscles that move the jaw, buccal cavity, and operculum. However, it is unclear when FBMNs first receive functional synaptic input from respiratory pattern-generating neurons, and how the functional output of the respiratory motor circuit changes across larval development. In the current study, we used behavior and calcium imaging to determine how early FBMNs receive functional synaptic inputs from respiratory pattern-generating networks in larval zebrafish. Zebrafish exhibited patterned operculum movements by 3 days postfertilization (dpf), though this behavior became more consistent at 4 and 5 dpf. Also by 3dpf, FBMNs fell into two distinct categories ("rhythmic" and "nonrhythmic"), based on patterns of neural activity. These two neuron categories were arranged differently along the dorsoventral axis, demonstrating that FBMNs have already established dorsoventral topography by 3 dpf. Finally, operculum movements were coordinated with pectoral fin movements at 3 dpf, indicating that the operculum behavioral pattern was driven by synaptic input. Taken together, this evidence suggests that FBMNs begin to receive initial synaptic input from a functional respiratory central pattern generator at or prior to 3 dpf. Future studies will use this model to study mechanisms of normal and abnormal respiratory circuit development.

Carotid Dissection Complicated by Polymorphic Ventricular Tachycardia.

In this case report, we describe a patient with fibromuscular dysplasia who suffered spontaneous bilateral carotid artery dissections. This was followed by significant variations in blood pressure and heart rates during her admission. Unfortunately, during an episode of bradycardia, a premature ventricular contraction occurred during the T wave which resulted in polymorphic ventricular tachycardia. As described in the case and in graphic depiction, this hemodynamic instability resolved after stenting of the carotid artery.

Association of Hospital Prices for Coronary Artery Bypass Grafting With Hospital Quality and Reimbursement.

Although prices for medical services are known to vary markedly between hospitals, it remains unknown whether variation in hospital prices is explained by differences in hospital quality or reimbursement from major insurers. We obtained "out-of-pocket" price estimates for coronary artery bypass grafting (CABG) from a random sample of US hospitals for a hypothetical patient without medical insurance. We compared hospital CABG price to (1) "fair price" estimate from Healthcare Bluebook data using each hospital's zip code and (2) Society of Thoracic Surgeons composite CABG quality score and risk-adjusted mortality rate. Of 101 study hospitals, 53 (52.5%) were able to provide a complete price estimate for CABG. The mean price for CABG was $151,271 and ranged from $44,824 to $448,038. Except for geographic census region, which was weakly associated with price, hospital CABG price was not associated with other structural characteristics or CABG volume (p >0.10 for all). Likewise, there was no association between a hospital's price for CABG with average reimbursement from major insurers within the same zip code (ρ = 0.07, p value = 0.6), Society of Thoracic Surgeoncomposite quality score (ρ = 0.08, p value = 0.71), or risk-adjusted CABG mortality (ρ = -0.03 p value = 0.89). In conclusion, the price of CABG varied more than 10-fold across US hospitals. There was no correlation between price information obtained from hospitals and the average reimbursement from major insurers in the same market. We also found no evidence to suggest that hospitals that charge higher prices provide better quality of care.

A birefringent reflector from a 1D anisotropic photonic crystal.

We demonstrate theoretically that a one-dimensional anisotropic photonic crystal can exhibit an absolute photonic band gap in which the propagation of light is prohibited for all polarizations and for a given incidence plane. Our structure is formed by the combination of a simple finite superlattice, composed of two alternating birefringent biaxial layers, with a cladding layer. The latter is made of the same material as one of the layers constituting the perfect superlattice, but with different orientation and thickness. We discuss whether the birefringence of the layers has a significant impact on the reflection gap. We have found that for reasonable values of structure parameters an absolute band gap can be obtained. Green's function method is used to derive the necessary expressions for our calculation. The effect of different parameters, namely, the orientation of the layers, the filling fraction, etc, is investigated to achieve a birefringent reflector.

Band structure and omnidirectional photonic band gap in lamellar structures with left-handed materials.

We theoretically investigate the photonic band structure of one-dimensional superlattices composed of alternating layers of right-handed and left-handed materials (RHM and LHM). The dispersion curves are mainly studied by assuming that the dielectric permittivity and magnetic permeability are constant in each layer. It is shown that such structures can exhibit new types of electromagnetic modes and dispersion curves that do not exist in usual superlattices composed only of RHM. In particular, we emphasize the possibility of bands that originate from the interface modes localized at the boundary between a LHM and RHM or from confined modes in one type of layers. These waves are evanescent in both or in one constituent of the superlattice. One of the pass bands may lie below the light lines of the constituting material and go down to the static limit of a vanishing frequency omega, even at a value of the wave vector k(//) (parallel to the layers) that is different from zero. For a given value of the wave vector k(//), the dispersion curves omega versus k(z) (where k(z) is the Bloch wave vector of the periodic system along the axis of the superlattice) may exist only in a limited part of the superlattice Brillouin zone and exhibit a zigzag behavior instead of a monotonic behavior as in usual superlattices. With an appropriate choice of the parameters, we show that it is possible to realize an absolute (or omnidirectional) band gap for either transverse electric (TE) or transverse magnetic (TM) polarization of the electromagnetic waves. A combination of two multilayer structures composed of RHM and LHM is proposed to realize, in a certain range of frequency, an omnidirectional reflector of light for both polarizations.

Omnidirectional elastic band gap in finite lamellar structures.

This paper presents a comprehensive theoretical analysis of the occurrence of omnidirectional reflection in one-dimensional phononic crystal structures. We discuss the conditions for a one-dimensional layered structure, made of elastic materials, to exhibit total reflection of acoustic incident waves in a given frequency range, for all incident angles and all polarizations. The property of omnidirectional reflection can be fulfilled with a simple finite superlattice if the substrate from which the incident waves are launched is made of a material with high acoustic velocities (this is very similar to the case of omnidirectional optical mirror where the incident light is generated in vacuum). However, if the substrate is made of a material with low acoustic velocities, we propose two solutions to obtain an omnidirectional band gap, namely, the cladding of a superlattice with a layer of high acoustic velocities, which acts like a barrier for the propagation of phonons, or the association in tandem of two different superlattices in such a way that the superposition of their band structures exhibits an absolute acoustic band gap. We discuss the appropriate choices of the material and geometrical properties to realize such structures. The behavior of the transmission coefficients are discussed in relation with the dispersion curves of the finite structure embedded between two substrates. Both transmission coefficients and densities of states (from which we derive the dispersion curves) are calculated in the framework of a Green's function method.