Undifferentiated Dyspnea with Point-of-Care Ultrasound, Primary Emergency Physician Compared with a Dedicated Emergency Department Ultrasound Team

BACKGROUND

Emergency physicians (EPs) perform critical actions while operating with diagnostic uncertainty. Point-of-care ultrasound (POCUS) is useful in evaluation of dyspneic patients. In prior studies, POCUS is often performed by ultrasound (US) teams without patient care responsibilities.

OBJECTIVES

This study evaluates the effectiveness of POCUS in narrowing diagnostic uncertainty in dyspneic patients when performed by treating EPs vs. separate US teams.

METHODS

This multicenter, prospective noninferiority cohort study investigated the effect of a POCUS performing team in patient encounters for dyspnea. Before-and-after surveys assessing medical decision-making were administered to attending physicians. Primary outcome was change in most likely diagnosis after POCUS. This was assessed for noninferiority between encounters where the primary or US team performed POCUS. Secondary outcomes included change in differential diagnosis, confidence in diagnosis, interventions considered, and image quality.

RESULTS

There were 156 patient encounters analyzed. In the primary team group, most likely diagnosis changed in 40% (95% confidence interval 28-52%) of encounters vs. 32% (95% confidence interval 22-41%) in the US team group. This was noninferior using an a priori specified margin of 20% (p < .0001). Post-POCUS differential decreased by a mean 1.8 diagnoses and was equivalent within a margin of 0.5 diagnoses between performing teams (p = 0.034). Other outcomes were similar between groups.

CONCLUSION

POCUS performed by primary teams was noninferior to POCUS performed by US teams for changing the most likely diagnosis, and equivalent when considering mean reduction in number of diagnoses. POCUS performed by treating EPs reduces cognitive burden in dyspneic patients.

Hypothalamic POMC Deficiency Improves Glucose Tolerance Despite Insulin Resistance by Increasing Glycosuria

Hypothalamic proopiomelanocortin (POMC) is essential for the physiological regulation of energy balance; however, its role in glucose homeostasis remains less clear. We show that hypothalamic arcuate nucleus (Arc)POMC-deficient mice, which develop severe obesity and insulin resistance, unexpectedly exhibit improved glucose tolerance and remain protected from hyperglycemia. To explain these paradoxical phenotypes, we hypothesized that an insulin-independent pathway is responsible for the enhanced glucose tolerance. Indeed, the mutant mice demonstrated increased glucose effectiveness and exaggerated glycosuria relative to wild-type littermate controls at comparable blood glucose concentrations. Central administration of the melanocortin receptor agonist melanotan II in mutant mice reversed alterations in glucose tolerance and glycosuria, whereas, conversely, administration of the antagonist Agouti-related peptide (Agrp) to wild-type mice enhanced glucose tolerance. The glycosuria of ArcPOMC-deficient mice was due to decreased levels of renal GLUT 2 (rGLUT2) but not sodium-glucose cotransporter 2 and was associated with reduced renal catecholamine content. Epinephrine treatment abolished the genotype differences in glucose tolerance and rGLUT2 levels, suggesting that reduced renal sympathetic nervous system (SNS) activity is the underlying mechanism for the observed glycosuria and improved glucose tolerance in ArcPOMC-deficient mice. Therefore, the ArcPOMC-SNS-rGLUT2 axis is potentially an insulin-independent therapeutic target to control diabetes.