Purpose “Attending rotations” on intensive care unit (ICU) services have been in place in most teaching hospitals for decades. However, the ideal frequency of patient care handoffs is unknown. Frequent attending physician handoffs could result in delays in care and other complications, while too few handoffs can lead to provider burnout and exhaustion. Therefore, we sought to determine the correlation between frequency of attending shifts with ICU charges, 30‐day readmission rates, and mortality rates. Methods We performed a retrospective cohort study at a large, urban, academic community hospital in Baltimore, MD. We included patients admitted into the cardiac or medical ICUs between September 1, 2012, and December 10, 2015. We tracked the number of attending shifts for each patient and correlated shifts with financial outcomes as a primary measure. Results For any given ICU length of stay, we found no distinct association between handoff frequency and charges, 30‐day readmission rates, or mortality rates. Conclusions Despite frequent handoffs in care, there was no objective evidence of care compromise or differences in cost. Further validation of these observations in a larger cohort is justified.

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Learning and behavior activate cue-specific patterns of sparsely distributed cells and synapses called ensembles that undergo memory-encoding engram alterations. While Fos is often used to label selectively activated cell bodies and identify neuronal ensembles, there is no comparable endogenous marker to label activated synapses and identify synaptic ensembles. For the purpose of identifying candidate synaptic activity markers, we optimized a flow cytometry of synaptoneurosome (FCS) procedure for assessing protein alterations in activated synapses from male and female rats. After injecting YFP-expressing AAV into medial prefrontal cortex (mPFC) to label terminals in nucleus accumbens (NAc) of rats, we injected 20 mg/kg of cocaine in a novel context (cocaine+novelty) to activate synapses, and prepared NAc synaptoneurosomes 0-60 min following injections. For FCS, we used commercially available antibodies to label pre- and post-synaptic markers synaptophysin and PSD-95 as well as candidate markers of synaptic activity (Arc, CaMKII and phospho-CaMKII, ribosomal protein S6, and phospho-S6, calcineurin and phospho-calcineurin) in YFP-labeled synaptoneurosomes. Cocaine+novelty increased the percentage of S6-positive synaptoneurosomes at 5-60 min and calcineurin-positive synaptoneurosomes at 5-10 min. Electron microscopy verified that S6 and calcineurin levels in synaptoneurosomes were increased 10 min after cocaine+novelty. Pretreatment with the anesthetic chloral hydrate blocked cocaine+novelty-induced S6 and calcineurin increases in synaptoneurosomes, indicating that these increases were due to neural activityper se. S6 levels were also increased by novel context exposure alone in the absence of cocaine. Overall, FCS can be used to study protein alterations in activated synapses coming from specifically labeled mPFC projections to NAc.SIGNIFICANCE STATEMENTMemories are formed during learning and stored in the brain by long-lasting molecular and cellular alterations called engrams formed within specific patterns of cue-activated neurons called neuronal ensembles. While Fos has been used to identify activated ensemble neurons and the engrams within them, we have not had a similar marker for activated synapses that can be used to identify synaptic engrams. Here we developed a flow cytometry procedure for high throughput in-line analysis of synaptoneurosomes (FCS) and found that ribosomal S6 protein and calcineurin were increased in activated mPFC to NAc synapses. FCS can be used to study protein alterations in activated synapses within specifically labeled circuits.