Intraoperative Dexmedetomidine for Reduction of Postoperative Delirium in the Elderly: A Scoping Review

Background/Purpose: Post-operative delirium leads to significant morbidity in elderly patients, yet there is no regimen to prevent POD. Opioid use in the elderly surgical population is of the most significant risk factors for developing POD. The purpose of this scoping review is to recognize that Dexmedetomidine mitigates cognitive dysfunction secondary to acute pain and the use of narcotic analgesia by decreasing the amount of norepinephrine (an excitatory neurotransmitter) released during times of stress. This mechanism of action also provides analgesia through decreased perception and modulation of pain. Methods: The authors developed eligibility criteria for inclusion of articles and performed a systematic search of several databases. Each of the authors initially selected five articles for inclusion in the scoping review. We created annotated literature tables for easy screening by co-authors. After reviewing the annotated literature table four articles were excluded, leaving 11 articles for inclusion in the scoping review. There were six level I meta-analysis/systematic reviews, four level II randomized clinical trials, and one level IV qualitative research article. Next, we created a data-charting form on Microsoft Word for extraction of data items and synthesis of results. Results: Two of the studies found no significant difference in POD between dexmedetomidine groups and control groups. The nine remaining studies noted decreases in the rate, duration, and risk of POD in the groups receiving dexmedetomidine either intraoperatively or postoperatively. Multiple studies found secondary benefits in addition to decreased POD, such as a reduction of tachycardia, hypertension, stroke, hypoxemia, and narcotic use. One study, however, found that the incidence of hypotension and bradycardia were increased among the elderly population. Implications for Nursing Practice: Surgery is a tremendous stressor in any age group, but especially the elderly population. It has been shown postoperative delirium occurs in 17-61% of major surgery procedures with 30-40% of the cases assumed to be preventable. Opioid administration in the elderly surgical population is one of the most significant risk factors for developing POD. With anesthesia practice already leaning towards opioid-free and opioid-limited anesthetic, the incorporation of dexmedetomidine could prove to be a valuable resource in both reducing opioid use and POD in the elderly surgical population. Although more research is needed, the current evidence is promising

Holographic flows to IR Lifshitz spacetimes

Recently we studied `vanishing' horizon limits of `boosted' black D3-brane geometry \cite{hsnr}. The type IIB solutions obtained by taking these special double limits were found to describe nonrelativistic Lifshitz spacetimes at zero temperature. In the present work we study these limits for TsT black-hole solutions which include $B$-field. The new Galilean solutions describe a holographic RG flow from Schr\"odinger ($a=2$) spacetime in UV to a Lifshitz universe ($a=3$) in the IR.Comment: 10 pages; v2: A bad typo in eq.8 corrected; v3: Discussion and reference on Kaigorodov spaces included, correction in sec-3, to be published in JHE

Constructing Lifshitz solutions from AdS

Under general assumptions, we show that a gravitational theory in d+1 dimensions admitting an AdS solution can be reduced to a d-dimensional theory containing a Lifshitz solution with dynamical exponent z=2. Working in a d=4, N=2 supergravity setup, we prove that if the AdS background is N=2 supersymmetric, then the Lifshitz geometry preserves 1/4 of the supercharges, and we construct the corresponding Killing spinors. We illustrate these results in examples from supersymmetric consistent truncations of type IIB supergravity, enhancing the class of known 4-dimensional Lifshitz solutions of string theory. As a byproduct, we find a new AdS4 x S1 x T(1,1) solution of type IIB.Comment: 29 pages, no figures; v2 minor corrections, a reference adde

Lifshitz black holes in string theory

We provide the first black hole solutions with Lifshitz asymptotics found in string theory. These are expected to be dual to models enjoying anisotropic scale invariance with dynamical exponent z=2 at finite temperature. We employ a consistent truncation of type IIB supergravity to four dimensions with an arbitrary 5-dimensional Einstein manifold times a circle as internal geometry. New interesting features are found that significantly differ from previous results in phenomenological models. In particular, small black holes are shown to be thermodynamically unstable, analogously to the usual AdS-Schwarzschild black holes, and extremality is never reached. This signals a possible Hawking-Page like phase transition at low temperatures.Comment: 19 pages, 7 figures. v2 references adde

Entangled-State Cycles of Atomic Collective-Spin States

We study quantum trajectories of collective atomic spin states of $N$ effective two-level atoms driven with laser and cavity fields. We show that interesting ``entangled-state cycles'' arise probabilistically when the (Raman) transition rates between the two atomic levels are set equal. For odd (even) $N$, there are $(N+1)/2$ ($N/2$) possible cycles. During each cycle the $N$-qubit state switches, with each cavity photon emission, between the states $(|N/2,m>\pm |N/2,-m>)/\sqrt{2}$, where $|N/2,m>$ is a Dicke state in a rotated collective basis. The quantum number $m$ ($>0$), which distinguishes the particular cycle, is determined by the photon counting record and varies randomly from one trajectory to the next. For even $N$ it is also possible, under the same conditions, to prepare probabilistically (but in steady state) the Dicke state $|N/2,0>$, i.e., an $N$-qubit state with $N/2$ excitations, which is of particular interest in the context of multipartite entanglement.Comment: 10 pages, 9 figure