Dexmedetomidine use in critical care

Effectiveness of nebulized dexmedetomidine for treatment of post-dural puncture headache in parturients undergoing elective cesarean section under spinal anesthesia: a randomized controlled study

PURPOSE

The need for effective treatment for post-dural puncture headache (PDPH) is a growing research entity. This study aimed to test the effectiveness of additional dexmedetomidine (DEX) to PDPH conservative management and evaluate its cerebral hemodynamic effects trans-cranial Doppler.

METHODS

This prospective randomized double-blind controlled trial was conducted on 43 post-partum females suffering from PDPH with visual analog score (VAS) ≥ 4 and Lybecker score ≥ 2. The study subjects were allocated into control group [n = 22] received nebulization of 4 mL 0.9% saline and DEX group [n = 21] received nebulization of 1 µg/kg DEX diluted in 4 mL 0.9% saline twice daily that was continued until achieving VAS score ≤ 3 and Lybecker score < 2 and/or for a maximum of 72 h. Both groups received routine conservative management. The primary outcome was the VAS and Lybecker scores and the secondary results were the DEX effects on cerebral vessels and the occurrence of any adverse effects.

RESULTS

VAS and Lybecker scores were significantly lower in DEX group. The middle cerebral artery mean flow velocity was significantly lower, and the pulsatility index was considerably higher after DEX nebulization compared to placebo. Two patients in the control group were indicated for epidural blood patch.

CONCLUSION

The addition of DEX nebulization (1 µg/kg twice daily) to the PDPH conservative care effectively relieved the symptoms and lowered pain scores which could be due to its analgesic and cerebral vasoconstrictive effects.

TRIAL REGISTRATION

This study was approved by the research ethical committee of Faculty of Medicine, Zagazig University with the reference number (ZU-IRB#: 6075/26-4-2020) and it was registered under clinicaltrials.gov (NCT04327726).

Dexmedetomidine suppresses bupivacaine-induced parthanatos in human SH-SY5Y cells via the miR-7-5p/PARP1 axis-mediated ROS

This study aims to explore the regulatory mechanisms of dexmedetomidine in parthanatos. MTT assay was applied to reveal cell viability; JC-1 staining assay was utilized to reveal mitochondrial membrane potential. Reactive oxygen species (ROS) probe, DCFH-DA, was used to detect intracellular ROS production. Luciferase activity assay was applied to measure the binding between miR-7-5p and PARP1. We first identified that bupivacaine inhibited the viability and induced the parthanatos of human neuroblastoma SH-SY5Y cells. In addition, dexmedetomidine, a potent α2-adrenoceptor agonist, reversed the regulatory effect of bupivacaine on parthanatos of SH-SY5Y. More importantly, dexmedetomidine counteracted bupivacaine-induced changes of mitochondrial membrane potential and ROS production in SH-SY5Y cells. Hyper-activation of PARP1 plays a vital role in parthanatos. Further exploration of our study identified that bupivacaine triggered overexpression of PARP1 in SH-SY5Y cells. Bioinformatics analysis revealed that miR-7-5p targeted the 3' untranslated region (3' UTR) of PARP1 to inhibit PARP1 expression. In addition, dexmedetomidine recovered the suppressive effects of bupivacaine on miR-7-5p expression. Dexmedetomidine suppressed bupivacaine-induced parthanatos in SH-SY5Y cells via the miR-7-5p/PARP1 axis, which may shed a new insight into parthanatos-dependent neuronal injury.

Antioxidant effects of dexmedetomidine against hydrogen peroxide-induced DNA damage in vitro by alkaline Comet assay

Background/aim

Dexmedetomidine (DEX) is an alpha-2 adrenergic agonist that is commonly used as a sedative and anesthetic. The protective effects of DEX against oxidative damage under both in vitro and in vivo conditions have been demonstrated. It was aimed to evaluate and compare the protective effects of DEX and vitamin C (Vit C) on DNA against H₂O₂-induced DNA damage in human lymphocyte cell cultures in vitro by alkaline Comet assay.

Materials and methods

Lymphocyte cell cultures were divided into 5 groups, as the negative control, solvent control, positive control, hydrogen peroxide (H₂O₂; 150 μM) + DEX (1 μM; 2.5 μM; 5 μM), and H₂O₂ (150 μM) + Vit C (1 μM; 2.5 μM; 5 μM), and incubated at 37 °C for 1 h. Cell viability was measured using the Trypan blue test. DNA damage was measured using the Alkali Comet Technique and the % percent tail intensity was evaluated. Statistical analysis was performed using 1-way ANOVA and the Tukey multiple comparison test.

Results

It was observed that H₂O₂ significantly induced DNA damage in the lymphocytes and this damage was decreased significantly with Vit C and DEX. It was observed that Vit C at doses of 1 μM and 2.5 μM had a significantly stronger antioxidant effect, but there was no significant difference between the antioxidant effects of Vit C and DEX with a dose of 5 μM. The dose of 5 μM DEX was found to be the most effective in reducing oxidative DNA damage.

Conclusion

There is limited data on the protective effects of DEX against oxidative DNA damage. The primary effect might be cytoprotection. The results herein showed that DEX was protective against H₂O₂-induced in vitro oxidative DNA damage in lymphocyte cell cultures in a dose-dependent manner. DEX might have a potential therapeutic value in the prevention of oxidative DNA damage in patients.

Effect of dexmedetomidine and midazolam for flexible fiberoptic bronchoscopy in intensive care unit patients: A retrospective study

This study aimed to investigate the clinical effectiveness of dexmedetomidine and midazolam for sedation of intensive care unit (ICU) patients requiring flexible fiberoptic bronchoscopy (FFB).This retrospective cohort study included 148 patients from the third ICU ward of the Second Affiliated Hospital of Harbin Medical University (Harbin, China) who received simultaneous invasive mechanical ventilation and FFB between March 2012 and December 2014. Patients were divided into dexmedetomidine (n  =  72) and midazolam (n  =  76) groups according to sedative mode. The sedative effects, incidence of adverse events, and bronchoscopist satisfaction scores were compared between groups.During FFB, total sedation time and total time of FFB were significantly shorter in the midazolam group (P < .001, respectively), with a lower percentage of these patients requiring propofol for remedial sedation (P < .001). The incidence of FFB-related adverse events (including bronchospasm, cough, and decreased oxygen saturation) was significantly higher in dexmedetomidine group compared with midazolam group (P  =  .007, .014 and .008, respectively). However, the incidence of other adverse events was not significantly different between groups. In addition, bronchoscopist satisfaction scores were significantly higher in the midazolam compared with dexmedetomidine group (7.72 ± 1.65 vs 7.08 ± 1.77; P  =  .030).For sedation of ICU patients during FFB, combination of midazolam and dexmedetomidine demonstrated an enhanced sedative effect, lower incidence of adverse events, and higher bronchoscopist satisfaction score compared with dexmedetomidine alone, thus represents a suitable alternative sedative for FFB patients.

Dexmedetomidine Attenuates Bilirubin-Induced Lung Alveolar Epithelial Cell Death In Vitro and In Vivo

Objective:

To investigate bilirubin-induced lung alveolar epithelial cell injury together with the protection afforded by dexmedetomidine.

Design:

Prospective, randomized, controlled study.

Setting:

Research laboratory.

Subjects:

Sprague Dawley rats.

Interventions:

Alveolar epithelial A549 cell lines were cultured and received bilirubin (from 0 to 160 μM) to explore the protective pathway of dexmedetomidine on bilirubin-induced alveolar epithelial cell injury assessed by immunochemistry and flow cytometry. Sprague-Dawley rats were subjected to common bile duct ligation surgery to explore the protective effect of dexmedetomidine on hyperbilirubinemia-induced alveolar epithelial cell injury and respiratory failure in comparison with the Sham (subjected to the surgery procedure but without bile duct ligation) or dexmedetomidine control (only received intraperitoneal injection of dexmedetomidine).

Measurements and Main Results:

In vitro, dexmedetomidine reversed the collapse of mitochondrial membrane potential (Δψm), upregulation of cytochrome C, B cell leukemia 2 associated X protein, and cleaved-caspase 3 and 9 in A549 epithelial cells with bilirubin challenge. Furthermore, dexmedetomidine reversed the arrest of cell cycle and the downregulation of the transforming growth factorβ, phosphorylated mammalian target of rapamycin, and p42/44 mitogen-activated protein kinase induced by bilirubin. In vivo, pulmonary edema and inflammation were found after common bile duct ligation. Bilirubin and Paco₂ were significantly increased, and oxygen (Pao₂) was significantly decreased in the blood of common bile duct ligation rats from the postsurgery day 7 to day 21 when compared with those in the sham controls, respectively (p < 0.01). Daily intraperitoneal injection of dexmedetomidine significantly alleviated the lung edema and injury and prevented respiratory failure.

Conclusion:

Our data both in vitro and in vivo demonstrated that dexmedetomidine protected alveolar epithelial cell from bilirubin-induced injury. Dexmedetomidine may be a good choice of anesthetic/sedative for patients with chronic liver disease during the perioperative period.

Pharmacokinetics of dexmedetomidine in Chinese post-surgical intensive care unit patients

BACKGROUND

Dexmedetomidine is a rather new drug in China. We sought to describe the pharmacokinetics of dexmedetomidine in patients requiring post-operative sedation and ventilation in our surgical intensive care unit.

METHODS

Twenty-two patients received post-operative infusions of dexmedetomidine at 6 μg/kg/h for 10 min, followed by 0.4 μg/kg/h for 350 min. Venous blood samples were drawn and assayed for plasma concentration. The pharmacokinetics were analysed using a nonlinear mixed-effect model with an interindividual and intraindividual error model. An initial estimation was performed to determine which of the one-, two- or three-compartment models is best to describe the concentration-time data. The covariates age, gender, weight, height, lean body mass (LBM), body surface area (BSA) and body mass index (BMI) were tested for significant effects on parameters using a stepwise forward addition and backward elimination approach. Covariate effects were judged based on changes in the objective function value (OFV).

RESULTS

The pharmacokinetics of dexmedetomidine were best described by a three-compartment model. The model was further improved when height was a covariate of systemic clearance (Cl1), with a decrease in OFV by -13.56 (P<0.01). From the heights of 155-178 cm, Cl1 increased by approximately 143%. The final pharmacokinetic parameter values were as follows: V1 =63.4 l, V2=41.3 l, V3 =284.3 l, Cl1=0.47×(height/160 cm)(6.42) l/min, Cl2=2.43 l/min and Cl3=0.086 l/min.

CONCLUSIONS

This study identified (i) the effect of height on the pharmacokinetics of dexmedetomidine; (ii) that there is no influence of age, gender, weight, LBM, BSA and BMI on pharmacokinetic parameters; and (iii) it established a preliminary population pharmacokinetic model for Chinese patients.