Low-dose Dexmedetomidine Research Articles

Effect of dexmedetomidineon minimum alveolar concentration of isoflurane required to inhibit the body movementduring skin incision

：Objective To investigatethe effect of dexmedetomidine on minimum alveolar concentration (MAC) of isofluranerequired to inhibit the body movement during skin incision. Methods Forty-eight ASA Ⅰ or Ⅱ patients aged 40-60 yr withbody mass index of 22-27 kg/m2 undergoing elective upper abdominal surgery under generalanesthesia were randomly divided into 3 groups: control group (group C, n = 15);low dosedexmedetomidine group (group D1, n = 17) and high dose dexmedetomidine group (group D2, n= 16). The patients were unpremedicated. Dexmedetomidine 0.4 and 0.8 μg/kgin normal saline (NS) 15 ml was infused over 15 min before induction of anesthesia in D1and D2 groups respectively. Anesthesia was induced with fentanyl-propofol-succinylcholine.The patients were mechanically ventilated after tracheal intubation. Anesthesia wasmaintained with isoflurane. MAC of isoflurane was determined by up-and-down technique. Theinitial end-tidal isofiurane concentration was set at 1.0%, 0.8% and 0.6% in C, D1 and D2groups respectively. Each time the end-tidal isoflurane concentration wasincreased/decreased by 0.2%. Skin incision was made after 15 min of equilibration, whenthe twitch height returned to more than 90% of its control value. Movement of body andlimbs including swallowing and coughing were carefully looked for when skin incision wasmade. MAC of isoflurane was the mean of end-tidal concentration of isoflurane of eachcrossover pair, and 95 % CI was calculated. Results MAC of isoflurane was significantlydecreased in D1 and D2 groups as compared with group C and in group D2 as compared withgroup D1( P ＜ 0.05or 0.01 ). Conclusion Dexmedetomidine can significantly decrease MAC of isofluranerequired to inhibit the body movement during skin incision in a dose-dependent manner. Key words: Dexmedetomidine; Dose-response relationship, drug; Isoflurane

Effect of increasing depth of dexmedetomidine anesthesia on upper airway morphology in children

This prospective study examines the dose-response effects of dexmedetomidine on upper airway morphology in children with no obstructive sleep apnea (OSA). To determine the effect of increasing doses of dexmedetomidine on static and dynamic magnetic resonance (MR) images of the upper airway in spontaneously breathing children with no OSA. General anesthetics and sedatives attenuate upper airway muscle activity, rendering the airway vulnerable to obstruction. Dose-response effects of dexmedetomidine on upper airway of children are not known. We prospectively examined the dose-response effects of dexmedetomidine on upper airway morphology in children. Increasing doses of dexmedetomidine was administered to 23 children scheduled for MR imaging of the brain while breathing spontaneously via the native airway. Static axial and dynamic sagittal midline MR ciné images of the upper airway were obtained during low (1 mcg.kg(-1).h(-1)) and high (3 mcg.kg(-1).h(-1)) doses of dexmedetomidine. The airway anteroposterior diameter, transverse diameter, and cross-sectional areas were measured manually by two independent observers. Static airway measurements were taken at the level of the nasopharyngeal airway (sagittal images) and retroglossal airway (RGA) (sagittal and axial images). Dynamic change in cross-sectional area of airway between inspiration and expiration was considered a measure of airway collapsibility. Static axial measurements of RGA did not change with increasing dose of dexmedetomidine. Most sagittal airway dimensions demonstrated clinically modest, although statistically significant, reductions with high dose compared to low dose dexmedetomidine. Although, the dynamic changes in nasopharyngeal and retroglossal area with respiration were marginally greater for high dose than for low dose dexmedetomidine, no subject exhibited any clinical evidence of airway obstruction. Upper airway changes associated with increasing doses of dexmedetomidine in children with no OSA are small in magnitude and do not appear to be associated with clinical signs of airway obstruction. Even though these changes are small, all precautions to manage airway obstruction should be taken when dexmedetomidine is used for sedation.

Dexmedetomidine used to provide hypotensive anesthesia during middle ear surgery

This study was carried out to assess the hypotensive effect of low dose dexmedetomidine (DEX) infusion during middle ear surgery. 42 ASA grades I and II patients of either sex aged 18-45 years undergoing elective middle ear surgery were randomly divided into two groups of 21 each. Group I received placebo bolus and infusion of saline at a rate similar to DEX in Group II. Group II received 10-15 min prior to induction of anesthesia 1 µg/kg IV bolus DEX diluted in 10 ml of normal saline over 10 min. Immediately thereafter an infusion of 0.4 µg/kg/hr of DEX commenced. Standard anesthetic technique was used. Halothane was titrated to achieve a mean arterial pressure 30% below the control value (value taken just after premedication). We observed that a statistically significant reduction in the percentage of halothane required to reduce MAP 30% below control value occurred in patients receiving DEX infusion (1.3 ± 0.4%) in comparison to those receiving placebo (3.1 ± 0.3%). Patients receiving DEX infusion had a better surgical field. The mean awakening time was significantly reduced in patients of Group II (9.1 ± 2.7 min) when compared to patients of Group I (12.8 ± 2.2 min).We conclude that DEX can be safely used to provide hypotensive anesthesia during middle ear surgery.

Antihyperalgesic effect of systemic dexmedetomidine and gabapentin in a rat model of monoarthritis

The present study investigated the effects of systemic administration of dexmedetomidine, a selective α2 adrenergic receptor (α2AR) agonist, and gabapentin either alone or in combination on thermal hyperalgesia evoked by ankle joint inflammation. Monoarthritis of rat ankle joint was induced by an intra-articular injection of Complete Freund's Adjuvant (CFA). The paw withdrawal latency (PWL) from a thermal stimulus was measured in awake rats. Intraperitoneal (i.p.) injection of dexmedetomidine (2.5, 5, 10 and 20 μg/kg) or gabapentin (25, 50, 100 and 200 mg/kg) significantly and dose-dependently increased the PWL of the hindpaw ipsilateral to CFA-injected joint. The PWLs of the non-injected and normal saline (NS)-injected hindpaws were not significantly affected by the two agents at the most doses tested except the highest dose of dexmedetomidine (20 μg/kg). Although low dose of dexmedetomidine (2.5 μg/kg) or gabapentin (25 mg/kg) alone did not affect or lightly increased PWLs of the hindpaw ipsilateral to CFA-injected joint, a combination of dexmedetomidine and gabapentin (2.5 μg/kg + 25 mg/kg, or 5μg/kg + 50 mg/kg) significantly reversed CFA-induced thermal hyperalgesia for 60 min without sedation/motor impairment. These results provide the first identification that co-application of dexmedetomidine and gabapentin may synergistically antagonize inflammatory pain, and this might prove to be beneficial in the treatment of arthritic pain.

Dexmedetomidine Weakens Dynamic Cerebral Autoregulation as Assessed by Transfer Function Analysis and the Thigh Cuff Method

Dexmedetomidine, which is often used in intensive care units in patients with compromised circulation, might induce further severe decreases in cerebral blood flow (CBF) with temporal decreases in arterial pressure induced by various stimuli if dynamic cerebral autoregulation is not improved. Therefore, the authors hypothesized that dexmedetomidine strengthens dynamic cerebral autoregulation. Fourteen healthy male subjects received placebo, low-dose dexmedetomidine (loading, 3 microg x kg(-1) x h(-1) for 10 min; maintenance, 0.2 microg x kg(-1) x h(-1) for 60 min), and high-dose dexmedetomidine (loading, 6 microg x kg(-1) x h(-1) for 10 min; maintenance, 0.4 microg x kg(-1) x h(-1) for 60 min) infusions in a randomized, double-blind, crossover study. After 70 min of drug administration, dynamic cerebral autoregulation was estimated by transfer function analysis between arterial pressure variability and CBF velocity variability, and the thigh cuff method. Compared with placebo, steady state CBF velocity and mean blood pressure significantly decreased during administration of dexmedetomidine. Transfer function gain in the very-low-frequency range increased and phase in the low-frequency range decreased significantly, suggesting alterations in dynamic cerebral autoregulation in lower frequency ranges. Moreover, the dynamic rate of regulation and percentage restoration in CBF velocity significantly decreased when a temporal decrease in arterial pressure was induced by thigh cuff release. Contrary to the authors' hypothesis, the current results of two experimental analyses suggest together that dexmedetomidine weakens dynamic cerebral autoregulation and delays restoration in CBF velocity during conditions of decreased steady state CBF velocity. Therefore, dexmedetomidine may lead to further sustained reductions in CBF during temporal decreases in arterial pressure.

Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

720. Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

720. Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

720: Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

720: Total Hip Artroplasty Under Spinal Anesthesia With Low-Dose Dexmedetomidine in Chronic Renal Failure Patients: A Primarily Clinical Evaluation

Dexmedetomidine: a review of clinical applications

The present review serves as an overview update in the diverse uses of the sedative dexmedetomidine. Dexmedetomidine is a selective alpha2 adrenoreceptor agonist that has been described as a useful, safe adjunct in many clinical applications. This paper reviews current clinical uses, mechanism of action, and side effects of dexmedetomidine. The current uses reviewed include sedation in the ICU (adult and pediatric), neurosurgery, pediatric procedural sedation, awake fiber-optic intubation, cardiac surgery, and bariatric surgery. Dexmedetomidine is a useful medication with many clinical applications. The medication has shown efficacy in decreasing the need for opioids, benzodiazepines, propofol, and other sedative medications. Short-term sedation has been shown to be safe in studies, although hypotension and bradycardia are the most significant side effects. Dexmedetomidine has been used effectively for sedation during pediatric procedures and in the ICU. In order to reduce sympathetic tone during cardiac surgery, a low-dose dexmedetomidine infusion has been utilized. The bariatric surgery population has also been studied with dexmedetomidine because of its adequate sedation and less prevalent respiratory depression when compared with opioid administration. Dexmedetomidine is emerging as an effective therapeutic agent in the management of a wide range of clinical conditions with an efficacious, safe profile.

Intravenous Sedation with Low-Dose Dexmedetomidine: Its Potential for Use in Dentistry

This study investigated the physiologic and sedative parameters associated with a low-dose infusion of dexmedetomidine (Dex). Thirteen healthy volunteers were sedated with Dex at a loading dose of 6 mcg/kg/h for 5 minutes and a continuous infusion dose of 0.2 mcg/kg/h for 25 minutes. The recovery process was observed for 60 minutes post infusion. The tidal volume decreased significantly despite nonsignificant changes in respiratory rate, minute ventilation, oxygen saturation, and end-tidal carbon dioxide. The mean arterial pressure and heart rate also decreased significantly but within clinically acceptable levels. Amnesia to pin prick was present in 69% of subjects. A Trieger dot test plot error ratio did not show a significant change at 30 minutes post infusion despite a continued significant decrease in bispectral index. We conclude that sedation with a low dose of Dex appears to be safe and potentially efficacious for young healthy patients undergoing dental procedures.

The effects of intra-operative low-dose dexmedetomidine infusion on postoperative pain in patients undergoing septorhinoplasty

Study objective: To determine the effects of intra-operative low-dose dexmedetomidine infusion on postoperative morphine consumption, pain, sedation and patient satisfaction in patients undergoing septorhinoplasty. Method: Fifty adult patients were randomised to receive either dexmedetomidine (a loading dose of 1 μg kg−1 for the first ten minutes and a maintenance dose of 0.2 μg kg−1 h−1 afterwards, Group D) or 0.9% saline in the same manner (Group C) after induction of anaesthesia. At the end of the operation, the infusions were discontinued. After extubation, patient controlled analgesia was started intravenously. Results: Patients in Group D consumed 47% less morphine than patients in Group C during the first 24 h and had a lower cumulative morphine consumption at all times after starting patient controlled analgesia (7.08 mg vs. 8.56 mg at 2 h (p < 0.05), 10.84 mg vs. 14.0 mg at 4 h (p < 0.05), 13.56 mg vs. 18.28 mg at 6 h (p < 0.05) and 17.96 mg vs. 33.72 mg at 24 h (p < 0.05), respectively in Group D and Group C). Visual analogue scale scores for pain were higher at all times in Group C than in Group D (p < 0.05). Sedation scores were higher in Group D than in Group C at 30 min after starting patient controlled analgesia (p < 0.05). Patient satisfaction scores were higher at all times in Group D than in Group C (p < 0.05). Conclusions: Intra-operative low-dose dexmedetomidine infusion during septorhinoplasty decreases postoperative morphine consumption, provides effective postoperative pain relief and achieves better patient satisfaction without increased adverse effects.

Paterson-Kelly Lesion

<h3>Objectives</h3> Whether and how delirium and sleep quality in the intensive care unit (ICU) are linked remains unclear. A recent randomised trial reported nocturnal low-dose dexmedetomidine (DEX) significantly reduces incident ICU delirium. Leeds Sleep Evaluation Questionnaire (LSEQ) scores were similar between intervention (DEX; n=50) and control (placebo (PLA); n=50) groups. We measured the association between morning LSEQ and delirium occurrence in the prior 24 hours (retrospective analysis) and the association between morning LSEQ and delirium occurrence in the following 24 hours (predictive analysis). <h3>Design</h3> Post hoc analysis of randomised controlled trial data. <h3>Participants</h3> Adult ICU patients (n=100) underwent delirium screening twice a day using the Intensive Care Delirium Screening Checklist (ICDSC) if Richmond Agitation Sedation Scale (RASS) was ≥−3 and patient-reported sleep quality evaluations at 09:00 daily with the LSEQ if RASS was ≥−1. <h3>Outcomes</h3> The analysis included all 24-hour study periods with LSEQ documentation and matched delirium screening in coma-free patients. Separate logistic regression models controlling for age, baseline Acute Physiology and Chronic Health Evaluation II score and DEX/PLA allocation evaluated the association between morning LSEQ and delirium occurrence for both retrospective and predictive analyses. <h3>Results</h3> The 100 patients spent 1115 24-hour periods in the ICU. Coma, delirium and no delirium occurred in 130 (11.7%), 114 (10.2%) and 871 (78.1%), respectively. In the retrospective analysis, when an LSEQ result was preceded by an ICDSC result (439/985 (44.6%) 24-hour periods), delirium occurred during 41/439 (9.3%) periods. On regression analysis, the LSEQ score had no relationship to prior delirium occurrence (OR (per every 1 point average LSEQ change) 0.97, 95% CI 0.72 to 1.31). For the predictive analysis, among the 387/985 (39.1%) 24-hour periods where an LSEQ result was followed by an ICDSC result, delirium occurred during 56/387 (14.5%) periods. On regression analysis, the LSEQ score did not predict subsequent delirium occurrence (OR (per 1 point LSEQ change) 1.02, 95% CI 0.99 to 1.05). <h3>Conclusions</h3> The sleep quality ICU patients perceive neither affects nor predicts delirium occurrence. <h3>Trial registration number</h3> NCT01791296