Sedation with midazolam worsens the diaphragm function than dexmedetomidine and propofol during mechanical ventilation in rats

Diaphragm blood flow: new avenues for human translation

The rhythmic contraction of the diaphragm facilitates continuous pulmonary ventilation essential for life. Adequate blood flow to the diaphragm is critical to continuously support contractile function, as an imbalance in nutritive supply and demand can lead to diaphragm insufficiency, patient morbidity, and mortality. Given oxygen supply to the diaphragm is key to its function, it is no surprise that more than 200 animal studies have investigated diaphragm blood flow ([Formula: see text]) regulation over the past century. This work has advanced our understanding of the diaphragm's circulatory control (i.e., regional blood flow heterogeneity and mechanical impediment) and response to a variety of conditions, including eupnea, exercise, hypoxia, hypercapnia, hemorrhage, mechanical ventilation, and pharmacological interventions. However, due to the relative inaccessibility of the diaphragm, few studies have been conducted in humans since [Formula: see text] measurements have historically required highly invasive and technically challenging techniques that are not conducive to routine use. Thus, our current understanding of [Formula: see text] is informed almost exclusively by animal work with conflicting findings, and its translation to humans is hindered by species-dependent variability in diaphragmatic structure and function. Novel approaches have been developed to quantify respiratory muscle blood flow in humans using minimally invasive techniques. More recently, contrast-enhanced ultrasound (CEUS) is a promising approach for quantifying [Formula: see text] in humans, independent from other respiratory muscles. Using novel approaches to quantify [Formula: see text] in humans, future research can aim to advance our understanding of [Formula: see text] in humans in health and disease, including exercise, sex-based comparisons, and critical care.

Dexmedetomidine improves prognosis in septic patients with myocardial injury and lower APACHE IV scores: a retrospective cohort study

BACKGROUND AND OBJECTIVE

Sepsis is a major cause of mortality, particularly in patients with myocardial injury. The objective of this study was to evaluate the impact of dexmedetomidine, propofol, and midazolam on mortality and various outcomes in this population.

METHODS

A retrospective cohort study was performed using the eICU database, encompassing 2,171 septic patients with myocardial injury. Patients were categorized into single- and multiple-sedative groups. The primary endpoint was 100-day mortality, with secondary endpoints encompassing hospital stay, intensive care unit (ICU) stay, mechanical ventilation (MV), and dialysis. Statistical analysis was conducted using Cox regression, Kaplan-Meier curves, and propensity score matching.

RESULTS

Among 2,171 patients, dexmedetomidine was associated with lower 100-day mortality in patients with APACHE IV scores < 78.9, particularly in specific subgroups. In patients with APACHE IV scores ≥ 78.9, dexmedetomidine provided no mortality advantage over propofol. Midazolam was linked to higher mortality across all score ranges, and its combination with propofol resulted in worse outcomes compared to dexmedetomidine-propofol. No significant differences were found in hospital stay, ICU stay, or MV rates between the groups.

CONCLUSION

Dexmedetomidine improves prognosis in septic patients with myocardial injury, particularly in those with lower severity of illness, highlighting its potential as a preferred sedative choice in this population.

Beneficial effects of the remifentanil/thiopental combination on cardiac function and redox status in diabetic rats

This study aimed to examine the effect of thiopental monotherapy as well as its combination with different agents used in anesthesia induction, on cardiac function and redox state of rats with type 1 diabetes mellitus (T1DM). A total of 40 Wistar albino male rats were used in this study and randomly divided into five groups: thiopental (TIO), fentanyl + thiopental (FEN + TIO), remifentanil + thiopental (REM + TIO), midazolam + thiopental (MID + TIO), and dexmedetomidine + thiopental (DEX + TIO). Animals were anesthetized by intraperitoneal injection of thiopental 85 mg/kg, fentanyl 0.005 mg/kg, remifentanil 0.04 mg/kg, midazolam 2.5 mg/kg, and dexmedetomidine 0.05 mg/kg of body weight. Four weeks after T1DM induction, all animals were subjected to a short narcosis of tested anesthetic, sacrificed by cervical dislocation and the hearts were retrogradely perfused according to Langendorff technique. Our research demonstrated that most combined anesthetics negatively influenced cardiodynamic parameters and redox state in diabetic rats. However, significantly improved cardiac contractility associated with enhanced antioxidative capacity was achieved in the combination of TIO with REM, which distinguishes this anesthetic combination as the therapy with the most pronounced positive effect on cardiac function in state of T1DM.

Investigation of the Protective Effects of Dexmedetomidine, Midazolam, Propofol, and Intralipid on Oxidative Stress and Inflammation in Rats with Lidocaine-Induced Toxicity

Aim

The aim of this study was to compare the effects of dexmedetomidine, midazolam, propofol, and intralipid on lidocaine-induced cardiotoxicity and neurotoxicity.

Methods

Forty-eight male Sprague-Dawley rats were randomly divided into six groups (n = 8 per group): control (C), lidocaine (L), lidocaine + dexmedetomidine (LD), lidocaine + midazolam (LM), lidocaine + propofol (LP), and lidocaine + intralipid (LI). Dexmedetomidine (100 µg/kg), midazolam (4 mg/kg), propofol (40 mg/kg), and intralipid (10 mg/kg) were administered intraperitoneally as pretreatment. Lidocaine (90 mg/kg) was administered intraperitoneally to induce oxidative stress in all groups except the control. After 60 minutes of electrocardiography (ECG) recording, the rats were sacrificed, and heart and brain tissue samples were collected. Comparative measurements of total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), and inflammatory parameters were conducted.

Results

In heart tissue samples, TAS was significantly higher in LI and LD groups (p < 0.05). Additionally, oxidative stress was significantly higher in the LM group (p < 0.05). Despite an increase in oxidative stress in brain tissue samples across all groups, it was found that all groups exhibited antioxidant protective effects (p < 0.05). Inflammatory parameters in heart and brain tissues significantly decreased in all groups, especially in the LI group (p < 0.05).

Conclusion

It was observed that pretreatment with midazolam increased oxidative stress induced by lidocaine, while dexmedetomidine and intralipid exhibited greater antioxidant effects. Dexmedetomidine and intralipid used as pretreatment were shown to be more effective in protecting against oxidative stress and inflammation.

Lung and Diaphragm Protection During Mechanical Ventilation in Patients with Acute Respiratory Distress Syndrome

Patients with acute respiratory distress syndrome often require mechanical ventilation to maintain adequate gas exchange and to reduce the workload of the respiratory muscles. Although lifesaving, positive pressure mechanical ventilation can potentially injure the lungs and diaphragm, further worsening patient outcomes. While the effect of mechanical ventilation on the risk of developing lung injury is widely appreciated, its potentially deleterious effects on the diaphragm have only recently come to be considered by the broader intensive care unit community. Importantly, both ventilator-induced lung injury and ventilator-induced diaphragm dysfunction are associated with worse patient-centered outcomes.

The Mechanism of α2 adrenoreceptor-dependent Modulation of Neurotransmitter Release at the Neuromuscular Junctions

α2-Adrenoreceptors (ARs) are main Gi-protein coupled autoreceptors in sympathetic nerve terminals and targets for dexmedetomidine (DEX), a widely used sedative. We hypothesize that α2-ARs are also potent regulators of neuromuscular transmission via G protein-gated inwardly rectifying potassium (GIRK) channels. Using extracellular microelectrode recording of postsynaptic potentials, we found DEX-induced inhibition of spontaneous and evoked neurotransmitter release as well as desynchronization of evoked exocytotic events in the mouse diaphragm neuromuscular junction. These effects were suppressed by SKF-86,466, a selective α2-AR antagonist. An activator of GIRK channels ML297 had the same effects on neurotransmitter release as DEX. By contrast, inhibition of GIRK channels with tertiapin-Q prevented the action of DEX on evoked neurotransmitter release, but not on spontaneous exocytosis. The synaptic vesicle exocytosis is strongly dependent on Ca2+ influx through voltage-gated Ca2+ channels (VGCCs), which can be negatively regulated via α2-AR - GIRK channel axis. Indeed, inhibition of P/Q-, L-, N- or R-type VGCCs prevented the inhibitory action of DEX on evoked neurotransmitter release; antagonists of P/Q- and N-type channels also suppressed the DEX-mediated desynchronization of evoked exocytotic events. Furthermore, inhibition of P/Q-, L- or N-type VGCCs precluded the frequency decrease of spontaneous exocytosis upon DEX application. Thus, α2-ARs acting via GIRK channels and VGCCs (mainly, P/Q- and N-types) exert inhibitory effect on the neuromuscular communication by attenuating and desynchronizing evoked exocytosis. In addition, α2-ARs can suppress spontaneous exocytosis through GIRK channel-independent, but VGCC-dependent pathway.

Perioperative Diaphragm Dysfunction

Diaphragm Dysfunction (DD) is a respiratory disorder with multiple causes. Although both unilateral and bilateral DD could ultimately lead to respiratory failure, the former is more common. Increasing research has recently delved into perioperative diaphragm protection. It has been established that DD promotes atelectasis development by affecting lung and chest wall mechanics. Diaphragm function must be specifically assessed for clinicians to optimally select an anesthetic approach, prepare for adequate monitoring, and implement the perioperative plan. Recent technological advancements, including dynamic MRI, ultrasound, and esophageal manometry, have critically aided disease diagnosis and management. In this context, it is noteworthy that therapeutic approaches for DD vary depending on its etiology and include various interventions, either noninvasive or invasive, aimed at promoting diaphragm recruitment. This review aims to unravel alternative anesthetic and operative strategies that minimize postoperative dysfunction by elucidating the identification of patients at a higher risk of DD and procedures that could cause postoperative DD, facilitating the recognition and avoidance of anesthetic and surgical interventions likely to impair diaphragmatic function.

YAP1 silencing attenuated lung injury/fibrosis but worsened diaphragmatic function by regulating oxidative stress and inflammation response in mice

Oxidative stress is a crucial mechanism in the pathophysiology of lung injury/fibrosis and diaphragmatic dysfunction. Yes-associated protein 1 (YAP1) is a key oxidative stress response regulator. However, how lung injury/fibrosis and the subsequent YAP1 silencing treatment affect diaphragmatic function remains largely uncharacterized. In this study, mice models of acute lipopolysaccharide (LPS) and paraquat exposure were used to establish acute lung injury and chronic pulmonary fibrosis. AT2 and C2C12 cells were co-cultured under LPS and paraquat challenge. YAP1 was interfered with shRNA given in vivo and verteporfin administration in vitro. Pulmonary histology, contractile properties, and cross-sectional areas (CSAs) of the diaphragm and gastrocnemius were evaluated. Histological and biochemical analyses were performed for targeted biomarker determination. We found that LPS and paraquat caused significant lung injury/fibrosis and significantly reduced the diaphragmatic-specific force and CSAs compared with the control. YAP1 silencing alleviated inflammatory cell infiltration or collagen deposition in the lungs yet worsened the already impaired diaphragmatic function by increasing inflammatory cytokines (IL-6 and TNF-α), mitochondrial reactive oxidative species (ROS) emission, protein degradation (Murf-1, atrogin-1, and calpain), and decreasing antioxidant capabilities (superoxide dismutase 2 and glutathione peroxidase). No significant improvements were observed in diaphragmatic function by transient YAP1 knockdown in the gastrocnemius. In vitro, LPS- or paraquat-caused cytotoxicity in AT2 cells was mostly alleviated by verteporfin in a concentration that was 20-fold higher than that in C2C12 cells (20 and 1 μg/mL, respectively). Finally, 0.5 μg/mL of verteporfin significantly ameliorated hydrogen peroxide-induced proteolytic activity and antioxidant enzyme suppression in C2C12 cells, whereas 2 μg/mL of verteporfin deteriorated the same. Collectively, lung injury/fibrosis adversely affects the diaphragm. YAP1 inhibition alleviates lung injury/fibrosis but worsens diaphragmatic function potentially by enhancing inflammatory cytokines and ROS-mediated protein degradation. This disparity might be attributed to differences in susceptibility to YAP1 inhibition between muscles and the lungs.

Effects of propofol on inflammatory response and activation of p38 MAPK signaling pathway in rats with ventilator-induced lung injury

Purpose:

To investigate the effects of propofol on inflammatory response and activation of p38 mitogen-activated protein kinase (MAPK) signaling pathway in rats with ventilator-associated lung injury (VALI).

Methods:

Thirty-six Sprague Dawley (SD) rats were divided into control, VALI and VALI+propofol groups. The VALI group received the mechanical ventilation for 2 h. The VALI+propofol group received the mechanical ventilation for 2 h, which was accompanied by intravenous injection of propofol with dose of 8 mg·kg^-1·h^-1. At the end, the mean arterial pressure (MAP) and blood gas indexes were measured, and the lung wet/dry mass ratio (W/D) and biochemical indexes of lung tissue and bronchoalveolar lavage fluid (BALF) were determined.

Results:

Compared with VALI group, in VALI+propofol group the blood pH, partial pressure of oxygen, partial pressure of carbon dioxide and MAP were increased, the lung W/D, lung tissue myeloperoxidase activity and total protein concentration, white blood cell count, and tumor necrosis factor α, interleukin 1β and interleukin 6 levels in BALF were decreased, and the p-p38 MAPK protein expression level and phosphorylated p38 MAPK (p-p38 MAPK)/p38 MAPK ratio were decreased.

Conclusions:

Propofol treatment may alleviate the VALI in rats by reducing the inflammatory response and inhibiting the activation of p38 MAPK signaling pathway.

Benzodiazepines: Their Use either as Essential Medicines or as Toxics Substances

This review highlights the nature, characteristics, properties, pharmacological differences between different types of benzodiazepines, the mechanism of action in the central nervous system, and the degradation of benzodiazepines. In the end, the efforts to reduce the benzodiazepines' adverse effects are shown and a reflection is made on the responsible uses of these medications.