Effects of Norepinephrine Infusion on Cutaneous Surface Temperatures of the Distal Extremities.

OBJECTIVES: The etiology of vasopressor-induced digital necrosis is poorly understood, but the skin changes resemble those of frostbite, and it is known from experience that patients taking vasopressors have decreased digital temperatures. We aimed to examine the effects of norepinephrine use on surface temperatures of the distal extremities because there have been no studies examining this relation. METHODS: Surface temperatures of all digits, palms, and soles were measured using an infrared thermometer in patients receiving different rates of norepinephrine infusion in the intensive care unit and compared with those not receiving any vasopressors. RESULTS: A total of 101 measurements from 41 unique individuals were obtained. Temperature gradients between the core and the fingertips were consistently more pronounced in those receiving norepinephrine compared with those not receiving norepinephrine and increased with increasing rates of norepinephrine infusion, except with high-dose norepinephrine. Temperature gradients were more pronounced in the toes. CONCLUSIONS: Norepinephrine use was associated with greater core-to-fingertip temperature gradients and were more pronounced in the toes compared with the fingers.

Diphenyl phosphine oxide-1-sensitive K(+) channels contribute to the vascular tone and reactivity of resistance arteries from brain and skeletal muscle.

OBJECTIVE: Many types of vascular smooth muscle cells exhibit prominent KDR currents. These KDR currents may be mediated, at least in part, by KV1.5 channels, which are sensitive to inhibition by DPO-1. We tested the hypothesis that DPO-1-sensitive KDR channels regulate the tone and reactivity of resistance-sized vessels from rat brain (MCA) and skeletal muscle (GA). METHODS: Middle cerebral and gracilis arteries were isolated and subjected to three kinds of experimental analysis: (i) western blot/immunocytochemistry; (ii) patch clamp electrophysiology; and (iii) pressure myography. RESULTS: Western blot and immunocytochemistry experiments demonstrated KV1.5 immunoreactivity in arteries and smooth muscle cells isolated from them. Whole-cell patch clamp experiments revealed smooth muscle cells from resistance-sized arteries to possess a KDR current that was blocked by DPO-1. Resistance arteries constricted in response to increasing concentrations of DPO-1. DPO-1 enhanced constrictions to PE and serotonin in gracilis and middle cerebral arteries, respectively. When examining the myogenic response, we found that DPO-1 reduced the diameter at any given pressure. Dilations in response to ACh and SNP were reduced by DPO-1. CONCLUSION: We suggest that KV1.5, a DPO-1-sensitive KDR channel, plays a major role in determining microvascular tone and the response to vasoconstrictors and vasodilators.

Inadvertent Disabling of Implantable Cardiac Defibrillator Antitachycardia Therapies Following Breast Reconstructive Surgery.

A 47-year-old woman with an implantable cardiac defibrillator and breast cancer underwent left breast mastectomy with simultaneous reconstruction using a breast tissue expander. She was found to have intermittent disabling of tachyarrhythmia detection and therapy functions of her implantable cardiac defibrillator that were triggered by the breast tissue expander magnetic port.