Critical Care Recovery Center: a model of agile implementation in intensive care unit (ICU) survivors.

BACKGROUND: As many as 70% of intensive care unit (ICU) survivors suffer from long-term physical, cognitive, and psychological impairments known as post-intensive care syndrome (PICS). We describe how the first ICU survivor clinic in the United States, the Critical Care Recovery Center (CCRC), was designed to address PICS using the principles of Agile Implementation (AI). METHODS: The CCRC was designed using an eight-step process known as the AI Science Playbook. Patients who required mechanical ventilation or were delirious ≥48 hours during their ICU stay were enrolled in the CCRC. One hundred twenty subjects who completed baseline HABC-M CG assessments and had demographics collected were included in the analysis to identify baseline characteristics that correlated with higher HABC-M CG scores. A subset of patients and caregivers also participated in focus group interviews to describe their perceptions of PICS. RESULTS: Quantitative analyses showed that the cognitive impairment was a major concern of caregivers. Focus group data also confirmed that caregivers of ICU survivors (n = 8) were more likely to perceive cognitive and mental health symptoms than ICU survivors (n = 10). Caregivers also described a need for ongoing psychoeducation about PICS, particularly cognitive and mental health symptoms, and for ongoing support from other caregivers with similar experiences. CONCLUSIONS: Our study demonstrated how the AI Science Playbook was used to build the first ICU survivor clinic in the United States. Caregivers of ICU survivors continue to struggle with PICS, particularly cognitive impairment, months to years after discharge. Future studies will need to examine whether the CCRC model of care can be adapted to other complex patient populations seen by health-care professionals.

Validation of a New Clinical Tool for Post-Intensive Care Syndrome.

BACKGROUND: Post-intensive care syndrome is defined as the long-term cognitive, physical, and psychological impairments due to critical illness. OBJECTIVE: To validate the self-report version of the Healthy Aging Brain Care Monitor as a clinical tool for detecting post-intensive care syndrome. METHODS: A total of 142 patients who survived a stay in an intensive care unit completed the Healthy Aging Brain Care Monitor Self-report and standardized assessments of cognition, psychological symptoms, and physical functioning. Cronbach α was used to measure the internal consistency of the scale items. Validity between the Healthy Aging Brain Care Monitor and comparison tests was measured by using Spearman correlation coefficients. Patients with post-intensive care syndrome were compared with a sample of primary care patients (known groups validity) by using the Mann-Whitney test. General linear models were used to adjust for age, sex, and education level. RESULTS: The total scale and all subscales had good to excellent internal consistency (Cronbach α, 0.83-0.92). Scores on the psychological subscale strongly correlated with standardized measures of psychological symptoms (Spearman correlation coefficient, 0.68-0.74). Results on the cognitive subscale correlated with the delayed memory measure (-0.51). Scores on the physical subscale correlated with the Physical Self-Maintenance Scale (-0.26). Patients with post-intensive care syndrome had significantly worse scores on subscales and total scores on the Healthy Aging Brain Care Monitor than did primary care patients. CONCLUSION: The self-report version of the Healthy Aging Brain Care Monitor is a valid clinical tool for assessing symptoms of post-intensive care syndrome.

Aging and Post-Intensive Care Syndrome: A Critical Need for Geriatric Psychiatry.

Because of the aging of the intensive care unit (ICU) population and an improvement in survival rates after ICU hospitalization, an increasing number of older adults are suffering from long-term impairments because of critical illness, known as post-intensive care syndrome (PICS). This article focuses on PICS-related cognitive, psychological, and physical impairments and the impact of ICU hospitalization on families and caregivers. The authors also describe innovative models of care for PICS and what roles geriatric psychiatrists could play in the future of this rapidly growing population.

Current purpose and practice of hypertonic saline in neurosurgery: a review of the literature.

OBJECTIVE: To review and summarize controversies and current concepts regarding the use of hypertonic saline during the perioperative period in neurosurgery. METHODS: Relevant literature was searched on PubMed and Scopus electronic databases to identify all studies that have investigated the use of hypertonic saline in neurosurgery. RESULTS: Fluid management during the course of neurosurgical practice has been debated at length, especially strategies to control intracranial pressure and small volume resuscitation. The goal of fluid therapy includes minimizing cerebral edema, preserving intravascular volume, and maintaining cerebral perfusion pressure. Mannitol is widely recognized as the gold standard for treating intracranial hypertension but can result in systemic hypotension. Thus, hypertonic saline provides volume expansion and may improve cerebral and systemic hemodynamics. Recently published prospective data, however, regarding the use of osmotic agents fails to establish clear guidelines in neurosurgical patients. CONCLUSIONS: We suggest that hypertonic saline will emerge as an alternative to mannitol, especially for a long-term use or multiple doses are needed and lead to a great opportunity for collaborative research.

SK2 channels are neuroprotective for ischemia-induced neuronal cell death.

In mouse hippocampal CA1 pyramidal neurons, the activity of synaptic small-conductance Ca(2+)-activated K(+) channels type 2 (SK2 channels) provides a negative feedback on N-methyl-D-aspartate receptors (NMDARs), reestablishing Mg(2+) block that reduces Ca(2+) influx. The well-established role of NMDARs in ischemia-induced excitotoxicity led us to test the neuroprotective effect of modulating SK2 channel activity following cerebral ischemia induced by cardiac arrest and cardiopulmonary resuscitation (CA/CPR). Administration of the SK channel positive modulator, 1-ethyl-benzimidazolinone (1-EBIO), significantly reduced CA1 neuron cell death and improved CA/CPR-induced cognitive outcome. Electrophysiological recordings showed that CA/CPR-induced ischemia caused delayed and sustained reduction of synaptic SK channel activity, and immunoelectron microscopy showed that this is associated with internalization of synaptic SK2 channels, which was prevented by 1-EBIO treatment. These results suggest that increasing SK2 channel activity, or preventing ischemia-induced loss of synaptic SK2 channels, are promising and novel approaches to neuroprotection following cerebral ischemia.

The SK2-long isoform directs synaptic localization and function of SK2-containing channels.

SK2-containing channels are expressed in the postsynaptic density (PSD) of dendritic spines on mouse hippocampal area CA1 pyramidal neurons and influence synaptic responses, plasticity and learning. The Sk2 gene (also known as Kcnn2) encodes two isoforms that differ only in the length of their N-terminal domains. SK2-long (SK2-L) and SK2-short (SK2-S) are coexpressed in CA1 pyramidal neurons and likely form heteromeric channels. In mice lacking SK2-L (SK2-S only mice), SK2-S-containing channels were expressed in the extrasynaptic membrane, but were excluded from the PSD. The SK channel contribution to excitatory postsynaptic potentials was absent in SK2-S only mice and was restored by SK2-L re-expression. Blocking SK channels increased the amount of long-term potentiation induced in area CA1 in slices from wild-type mice but had no effect in slices from SK2-S only mice. Furthermore, SK2-S only mice outperformed wild-type mice in the novel object recognition task. These results indicate that SK2-L directs synaptic SK2-containing channel expression and is important for normal synaptic signaling, plasticity and learning.

Optogenetic photochemical control of designer K+ channels in mammalian neurons.

Currently available optogenetic tools, including microbial light-activated ion channels and transporters, are transforming systems neuroscience by enabling precise remote control of neuronal firing, but they tell us little about the role of indigenous ion channels in controlling neuronal function. Here, we employ a chemical-genetic strategy to engineer light sensitivity into several mammalian K(+) channels that have different gating and modulation properties. These channels provide the means for photoregulating diverse electrophysiological functions. Photosensitivity is conferred on a channel by a tethered ligand photoswitch that contains a cysteine-reactive maleimide (M), a photoisomerizable azobenzene (A), and a quaternary ammonium (Q), a K(+) channel pore blocker. Using mutagenesis, we identify the optimal extracellular cysteine attachment site where MAQ conjugation results in pore blockade when the azobenzene moiety is in the trans but not cis configuration. With this strategy, we have conferred photosensitivity on channels containing Kv1.3 subunits (which control axonal action potential repolarization), Kv3.1 subunits (which contribute to rapid-firing properties of brain neurons), Kv7.2 subunits (which underlie "M-current"), and SK2 subunits (which are Ca(2+)-activated K(+) channels that contribute to synaptic responses). These light-regulated channels may be overexpressed in genetically targeted neurons or substituted for native channels with gene knockin technology to enable precise optopharmacological manipulation of channel function.

Neurotransmitter modulation of small-conductance Ca2+-activated K+ channels by regulation of Ca2+ gating.

Small-conductance Ca2+-activated K+ (SK) channels are widely expressed in neuronal tissues where they underlie post-spike hyperpolarizations, regulate spike-frequency adaptation, and shape synaptic responses. SK channels constitutively interact with calmodulin (CaM), which serves as Ca2+ sensor, and with protein kinase CK2 and protein phosphatase 2A, which modulate their Ca2+ gating. By recording coupled activities of Ca2+ and SK2 channels, we showed that SK2 channels can be inhibited by neurotransmitters independently of changes in the activity of the priming Ca2+ channels. This inhibition involvesSK2-associated CK2 and results from a 3-fold reduction in the Ca2+ sensitivity of channel gating. CK2phosphorylated SK2-bound CaM but not KCNQ2-bound CaM, thereby selectively regulating SK2 channels. We extended these observations to sensory neurons by showing that noradrenaline inhibits SK current and increases neuronal excitability in aCK2-dependent fashion. Hence, neurotransmitter-initiated signaling cascades can dynamically regulate Ca2+ sensitivity of SK channels and directly influence somatic excitability.

Organization and regulation of small conductance Ca2+-activated K+ channel multiprotein complexes.

Small conductance Ca2+-activated K+ channels (SK channels) are complexes of four alpha pore-forming subunits each bound by calmodulin (CaM) that mediate Ca2+ gating. Proteomic analysis indicated that SK2 channels also bind protein kinase CK2 (CK2) and protein phosphatase 2A (PP2A). Coexpression of SK2 with the CaM phosphorylation surrogate CaM(T80D) suggested that the apparent Ca2+ sensitivity of SK2 channels is reduced by CK2 phosphorylation of SK2-bound CaM. By using 4,5,6,7-tetrabromo-2-azabenzimidazole, a CK2-specific inhibitor, we confirmed that SK2 channels coassemble with CK2. PP2A also binds to SK2 channels and counterbalances the effects of CK2, as shown by coexpression of a dominant-negative mutant PP2A as well as a mutant SK2 channel no longer able to bind PP2A. In vitro binding studies have revealed interactions between the N and C termini of the channel subunits as well as interactions among CK2 alpha and beta subunits, PP2A, and distinct domains of the channel. In the channel complex, lysine residue 121 within the N-terminal domain of the channel activates SK2-bound CK2, and phosphorylation of CaM is state dependent, occurring only when the channels are closed. The effects of CK2 and PP2A indicate that native SK2 channels are multiprotein complexes that contain constitutively associated CaM, both subunits of CK2, and at least two different subunits of PP2A. The results also show that the Ca2+ sensitivity of SK2 channels is regulated in a dynamic manner, directly through CK2 and PP2A, and indirectly by Ca2+ itself via the state dependence of CaM phosphorylation by CK2.

An inbred 129SvEv GFPCre transgenic mouse that deletes loxP-flanked genes in all tissues.

A common method for generating mice with subtle genetic manipulations uses homologous recombination (HR) in embryonic stem (ES) cells to replace a wild-type gene with a slightly modified one. Generally, a drug resistance gene is inserted with the modified gene to select correctly targeted clones. Often, however, the presence of this drug resistance gene interferes with the normal locus and creates a null or hypomorphic allele. Flanking of the selectable marker by loxP sites followed by Cre-mediated deletion after drug selection can overcome this problem. The simplest method used to remove a loxP-flanked selectable marker is to breed an animal carrying a loxP-flanked drug resistance gene to an animal that expresses Cre recombinase in the germline. To date only outbred transgenic mice are available for this purpose. This can be problematic for phenotypic analysis in many organ systems, including the brain, and for the analysis of behavior. While attempting to make 129S6/SvEvTac inbred background (isogenic to our ES cells) mice that express Cre under the control of several tissue-specific promoters, we serendipitously generated a line that excises loxP-flanked drug resistance genes in all tissues, including the germline. This reagent allows deletion of loxP-flanked sequences while maintaining the mutation on an inbred background.

Loss of neuropathy target esterase in mice links organophosphate exposure to hyperactivity.

Neuropathy target esterase (NTE) is involved in neural development and is the target for neurodegeneration induced by selected organophosphorus pesticides and chemical warfare agents. We generated mice with disruptions in Nte, the gene encoding NTE. Nte(-/-) mice die after embryonic day 8, and Nte(+/-) mice have lower activity of Nte in the brain and higher mortality when exposed to the Nte-inhibiting compound ethyl octylphosphonofluoridate (EOPF) than do wild-type mice. Nte(+/-) and wild-type mice treated with 1 mg per kg of body weight of EOPF have elevated motor activity, showing that even minor reduction of Nte activity leads to hyperactivity. These studies show that genetic or chemical reduction of Nte activity results in a neurological phenotype of hyperactivity in mammals and indicate that EOPF toxicity occurs directly through inhibition of Nte without the requirement for Nte gain of function or aging.