Association between timing of speech and language therapy initiation and outcomes among post-extubation dysphagia patients: a multicenter retrospective cohort study.

BACKGROUND: Post-extubation dysphagia (PED) is recognized as a common complication in the intensive care unit (ICU). Speech and language therapy (SLT) can potentially help improve PED; however, the impact of the timing of SLT initiation on persistent PED has not been well investigated. This study aimed to examine the timing of SLT initiation and its effect on patient outcomes after extubation in the ICU. METHODS: We conducted this multicenter, retrospective, cohort study, collecting data from eight ICUs in Japan. Patients aged ≥ 20 years with orotracheal intubation and mechanical ventilation for longer than 48 h, and those who received SLT due to PED, defined as patients with modified water swallowing test scores of 3 or lower, were included. The primary outcome was dysphagia at hospital discharge, defined as functional oral intake scale score < 5 or death after extubation. Secondary outcomes included dysphagia or death at the seventh, 14th, or 28th day after extubation, aspiration pneumonia, and in-hospital mortality. Associations between the timing of SLT initiation and outcomes were determined using multivariable logistic regression. RESULTS: A total of 272 patients were included. Of them, 82 (30.1%) patients exhibited dysphagia or death at hospital discharge, and their time spans from extubation to SLT initiation were 1.0 days. The primary outcome revealed that every day of delay in SLT initiation post-extubation was associated with dysphagia or death at hospital discharge (adjusted odds ratio (AOR), 1.09; 95% CI, 1.02-1.18). Similarly, secondary outcomes showed associations between this per day delay in SLT initiation and dysphagia or death at the seventh day (AOR, 1.28; 95% CI, 1.05-1.55), 14th day (AOR, 1.34; 95% CI, 1.13-1.58), or 28th day (AOR, 1.21; 95% CI, 1.07-1.36) after extubation and occurrence of aspiration pneumonia (AOR, 1.09; 95% CI, 1.02-1.17), while per day delay in post-extubation SLT initiation did not affect in-hospital mortality (AOR, 1.04; 95% CI, 0.97-1.12). CONCLUSIONS: Delayed initiation of SLT in PED patients was associated with persistent dysphagia or death. Early initiation of SLT may prevent this complication post-extubation. A randomized controlled study is needed to validate these results.

Intrathecal Administration of the α1 Adrenergic Antagonist Phentolamine Upregulates Spinal GLT-1 and Improves Mirror Image Pain in SNI Model Rats.

Mirror image pain (MIP) is a type of extraterritorial pain that results in contralateral pain or allodynia. Glutamate transporter-1 (GLT-1) is expressed in astrocytes and plays a role in maintaining low glutamate levels in the synaptic cleft. Previous studies have shown that GLT-1 dysfunction induces neuropathic pain. Our previous study revealed bilateral GLT-1 downregulation in the spinal cord of a spared nerve injury (SNI) rat. We hypothesized that spinal GLT-1 is involved in the mechanism of MIP. We also previously demonstrated noradrenergic GLT-1 regulation. Therefore, this study aimed to investigate the effect of an α1 adrenergic antagonist on the development of MIP. Rats were subjected to SNI. Changes in pain behavior and GLT-1 protein levels in the SNI rat spinal cords were then examined by intrathecal administration of the α1 adrenergic antagonist phentolamine, followed by von Frey test and western blotting. SNI resulted in the development of MIP and bilateral downregulation of GLT-1 protein in the rat spinal cord. Intrathecal phentolamine increased contralateral GLT-1 protein levels and partially ameliorated the 50% paw withdrawal threshold in the contralateral hind paw. Spinal GLT-1 upregulation by intrathecal phentolamine ameliorates MIP. GLT-1 plays a role in the development of MIPs.

Norepinephrine-induced downregulation of GLT-1 mRNA in rat astrocytes.

AIM OF THE RESEARCH: Glutamate transporter-1 (GLT-1; also known as excitatory amino acid transporter 2) plays an important role in the maintenance of glutamate homeostasis in the synaptic cleft. Downregulation of GLT-1 in the spinal cord has been reported in chronic pain models, which suggests that GLT-1 is involved in the development of chronic pain. However, the mechanism by which GLT-1 is downregulated in the spinal cord is still unknown. We hypothesized that norepinephrine is involved in the regulation of GLT-1. The aim of this study was to investigate the effect of norepinephrine on GLT-1 expression in cultured astrocytes. METHODS: This study involved both in vivo and in vitro experiments. We first validated changes in GLT-1 mRNA expression in the spinal cord of rats with spared nerve injury (SNI) using real-time RT-PCR. Next, cultured primary astrocytes from the rat spinal cord were stimulated with norepinephrine, and GLT-1 mRNA was subsequently quantitated. RNB cells, an astrocytic cell line, were also stimulated with norepinephrine and other α-adrenoceptor agonists. RESULTS: SNI resulted in bilateral downregulation of GLT-1 in rat spinal cord. The in vitro study showed that norepinephrine and phenylephrine dose-dependently downregulated GLT-1 in primary astrocytes and RNB cells. Furthermore, the effect of norepinephrine was reversed by an α-adrenoceptor antagonist. CONCLUSION: Norepinephrine downregulates GLT-1 mRNA expression in astrocytes via the α1-adrenoceptor. Our results provide new insight into the mechanisms involved in downregulation of GLT-1 in the chronic pain models.

Decreased expression of hyaluronan synthase and loss of hyaluronan-rich cells in the anterior tibial fascia of the rat model of chemotherapy-induced peripheral neuropathy.

Introduction: Previous studies on chemotherapy-induced peripheral neuropathy (CIPN) have focused on neuronal damage. Although some studies have revealed that the fascia is an important sensory organ, currently, we do not know about chemotherapy drug-induced fascial dysfunction. Objectives: This study aimed to explore the fascia as a nonneural cause of mechanical hypersensitivity in CIPN by investigating the expression of hyaluronic acid synthase (HAS) and histology of the fascia in an animal model of CIPN. Methods: Rats were intraperitoneally administered with vincristine (VCR). Mechanical hypersensitivities of the hind paw and the anterior tibial muscle were assessed. The expression of HAS mRNA in the fascia of the anterior tibial muscles was quantitated using reverse transcription polymerase chain reaction. Immunohistochemistry was also performed for HAS2, hyaluronic acid-binding protein, and S100A4 in the fascia. Results: Vincristine administration significantly decreased mechanical withdrawal thresholds in the hind paw and the anterior tibial muscle after day 3. Quantitative polymerase chain reaction showed significant downregulation of HAS mRNAs in the fascia of VCR-treated rats. Immunohistochemical analysis showed that the number of cells with strong HAS2 immunoreactivity, classified as fasciacytes by morphology and colocalized marker S100A4, decreased significantly in the VCR group. Conclusion: Hyaluronic acid plays a critical role in somatic pain sensation. Damaged fascia could be a possible cause of musculoskeletal pain in patients with CIPN. This study suggests that fascia is a nonneural cause and novel therapeutic target for chemotherapy-induced "peripheral neuropathy."