Optimal effect-site concentration of remifentanil when combined with dexmedetomidine in patients undergoing cystoscopy

Efficacy of dexmedetomidine-ketamine vs. fentanylketamine on saturated oxygen, hemodynamic responses and sedation in cystoscopy: a doubleblinded randomized controlled clinical trial

Cystoscopy is a diagnostic and invasive procedure for treatment and follow-up of genitourinary system patients and could be performed with a variety of anesthesia techniques. The study aimed to assess the efficacy of dexmedetomidine-ketamine vs. fentanyl-ketamine on sedation and analgesia for cystoscopy. This double-blind randomized controlled clinical trial enrolled 60 patients undergoing cystoscopy in two groups. Patients were assigned randomly by block random allocation method into dexmedetomidine-ketamine group (1 μg/kg dexmedetomidine) and fentanyl-ketamine group (2 μg/kg fentanyl) receiving ketamine (0.5 mg/kg). Subsequently, mean blood pressure, heart rate, saturated oxygen, respiratory rate, pain intensity, Ramsay score for sedation level, cystoscopy duration, and urologic satisfaction were measured and compared between two groups. Both the groups were similar regarding age, sex and baseline hemodynamic parameters (P > 0.05). Lower heart rate and pain score were revealed in the dexmedetomidine-ketamine group at 25–50 and 30–60 minutes, respectively, after cystoscopy (P < 0.05). Moreover, repeated measure test showed that there was significant difference in trend of respiratory rate and pain score between two groups (P = 0.017) and was lower in dexmedetomidine-ketamine group. The dexmedetomidine-ketamine group relieves pain 30 minutes after cystoscopy with stable hemodynamic parameters during operation. Therefore, dexmedetomidine-ketamine is recommended to be employed for pain relief in subjects undergoing cystoscopy. The study was approved by Ethical Committee of Arak University of Medical Sciences with IR.ARAKMU.REC.1397.108 on July 2, 2018, and registered in Iranian Registry Clinical Trial center with code IRCT20141209020258N105 on April 21, 2019.

Optimal effect-site concentration of remifentanil to prevent hemodynamic changes during nasotracheal intubation using a video laryngoscope

Background

Nasotracheal intubation is the most commonly used method to secure the field of view when performing surgery on the oral cavity or neck. Like orotracheal intubation, nasotracheal intubation uses a laryngoscope. Hemodynamic change occurs due to the stimulation of the sympathetic nervous system. Recently, video laryngoscope with a camera attached to the end of the direct laryngoscope blade has been used to minimize this change. In this study, we investigated the optimal effect-site concentration (Ce) of remifentanil for minimizing hemodynamic responses during nasotracheal intubation with a video laryngoscope.

Methods

Twenty-one patients, aged between 19 and 60 years old, scheduled for elective surgery were included in this study. Anesthesia was induced by slowly injecting propofol. At the same time, remifentanil infusion was initiated at 3.0 ng/ml via target-controlled infusion (TCI). When remifentanil attained the preset Ce, nasotracheal intubation was performed using a video laryngoscope. The patient's blood pressure and heart rate were checked pre-induction, right before and after intubation, and 1 min after intubation. Hemodynamic stability was defined as an increase in systolic blood pressure and heart rate by 20% before and after nasotracheal intubation. The response of each patient determined the Ce of remifentanil for the next patient at an interval of 0.3 ng/ml.

Results

The Ce of remifentanil administered ranged from 2.4 to 3.6 ng/ml for the patients evaluated. The estimated optimal effective effect-site concentrations of remifentanil were 3.22 and 4.25 ng/ml, that were associated with a 50% and 95% probability of maintaining hemodynamic stability, respectively.

Conclusion

Nasotracheal intubation using a video laryngoscope can be successfully performed in a hemodynamically stable state by using the optimal remifentanil effect-site concentration (Ce₅₀, 3.22 ng/ml; Ce₉₅, 4.25 ng/ml).

Anesthetic management for medialization laryngoplasty using concurrent infusions of dexmedetomidine, remifentanil, and propofol versus controls

PURPOSE

Medialization laryngoplasty (ML) ± arytenoid adduction (AA) surgery poses a unique anesthetic challenge that requires periods of deep sedation and patient cooperation with phonation to assess voice function. The purpose of this study was to assess if the protocolized administration of dexmedetomidine, remifentanil, and propofol (DRP) is associated with reduced procedural duration and administration of other sedating medications.

MATERIALS AND METHODS

This was a retrospective 2:1 case matched study design; matched on age, sex, body mass index, AA, and surgical revision status. Data was obtained from the electronic medical record of a tertiary referral center. Cases underwent ML ± AA using DRP. Control subjects underwent surgery ML ± AA without DRP.

RESULTS

58 DRP cases (43.1% AA) were matched with 116 control patients (44.8% AA). DRP was associated with decreases in fentanyl dose (50 [25, 100] vs. 100 [50, 150] mcg; p < 0.01), incidence and dose of midazolam (4 [6.9%] vs. 70 [60.3%]; p < 0.01; 1 [1, 1] vs. 2 [2, 2]; p < 0.02), operative duration (131 ± 33 vs. 160 ± 50 min; p < 0.01), and anesthetic duration (182 ± 35 vs. 219 ± 60.3 min; p < 0.01). When adjusted for timeline, it was observed that case duration was declining prior to DRP introduction; this trend persisted after DRP introduction. Hypopnea was more common with DRP (14 [24.1%] vs. 7 [6.0%]; p < 0.01).

CONCLUSIONS

DRP was associated with a substantial decrease in opioid and benzodiazepine administration. A reduction in procedural duration over time was also observed.

Anesthetic Management for Medialization Laryngoplasty Performed Under Concurrent Dexmedetomidine, Remifentanil, and Propofol Infusions

INTRODUCTION

Type I thyroplasty, or medialization larygoplasty (ML), is a procedure which improves the voice by medializing a vocal fold with a permanent implant. Anesthetic management of these cases is challenging because patients can require periods of deep sedation followed by fully awake moments for phonation to assess the implant size. We present our experience of ML with or without arytenoid adduction (AA) using a multimodal anesthetic regimen consisting of concurrent infusions of dexmedetomidine, remifentanil, and propofol.

METHODS

This is a retrospective case series of patients anesthetized using this protocol from June 1, 2015 through June 30, 2017.

RESULTS

Seventy-five consecutive ML with or without AA patients anesthetized with dexmedetomidine and remifentanil infusions were identified, of which 74 (98.7%) also received concurrent propofol infusions. Mean duration of sedation was 190.9 ± 36.9 minutes and surgery was 139 ± 35.3 minutes. Transient hypopnea treated with supplemental oxygen complicated 18 (24%) cases and bradycardia requiring pharmacologic treatment complicated 3 (4%) cases. There were no other adverse anesthetic complications. One patient required surgical re-exploration due to postsurgical bleeding after the initial hospital discharge.

CONCLUSION

In this cohort, a combination of remifentanil, dexmedetomidine and propofol infusions was well tolerated without serious adverse perioperative events.

Optimal effective-site concentration of remifentanil for sedation during plate removal of maxilla

Background

Removal of the plate following Le Fort I osteotomy and BSSO (bilateral sagittal split osteotomy) is a common procedure. However, patients who undergo plate removal experience intense pain and discomfort. This study investigated the half-maximal effective concentration (Ce₅₀) of remifentanil in the prevention of plate removal pain under sedation using dexmedetomidine.

Methods

The study evaluated 18 patients, between 18 and 35 years of age, scheduled for elective surgery. Remifentanil infusion was initiated after sedation using dexmedetomidine, and started at a dose of 1.5 ng/mL on the first patient via target-controlled infusion (TCI). Patients received a loading dose of 1.0 µg/kg dexmedetomidine over 10 min, followed by a maintenance dose of 0.7 µg/kg/h. When the surgeon removed the plate, the patient Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score was observed.

Results

The Ce of remifentanil ranged from 0.9 to 2.1 ng/mL for the patients evaluated. The estimated effect-site concentrations of remifentanil associated with a 50% and 95% probability of reaching MOAA/S score of 3 were 1.28 and 2.51 ng/mL, respectively.

Conclusions

Plate removal of maxilla can be successfully performed without any pain or adverse effects by using the optimal remifentanil effect-site concentration (Ce₅₀, 1.28 ng/mL; Ce₉₅, 2.51 ng/mL) combined with sedation using dexmedetomidine.

Prevention of Remifentanil Induced Postoperative Hyperalgesia by Dexmedetomidine via Regulating the Trafficking and Function of Spinal NMDA Receptors as well as PKC and CaMKII Level In Vivo and In Vitro

Remifentanil-induced secondary hyperalgesia has been demonstrated in both animal experiments and clinical trials. Enhancement of N-methyl-D-aspartate (NMDA) receptor trafficking as well as protein kinase C (PKC) and calmodulin-dependent protein kinase II (CaMKII) have been reported to be involved in the induction and maintenance of central sensitization. In the current study, it was demonstrated that dexmedetomidine could prevent remifentanil-induced hyperalgesia (RIH) via regulating spinal NMDAR-PKC-Ca2+/ CaMKII pathway in vivo and in vitro. We firstly investigated the effect of dexmedetomidine, a highly selective α2-adrenergic receptor agonist, on mechanical and thermal hyperalgesia using a rat model of RIH. NMDA receptor subunits (NR1, NR2A and NR2B) expression and membrane trafficking as well as PKC and CaMKII expression in spinal cord L4-L5 segments were measured by Western blot analysis. The expression of NMDA receptor subunits (NR1, NR2A and NR2B) were also detected by immunohistochemistry. Further more, the effect of dexmedetomidine on NMDA receptor current amplitude and frequency in spinal cord slices were investigated by whole-cell patch-clamp recording. We found that remifentail infusion at 1.2 μg.kg-1.min-1 for 90 min caused mechanical and thermal hyperalgesia, up-regulated NMDA receptor subunits NR1 and NR2B expression in both membrane fraction and total lysate as well as increased PKC and CaMKII expression in spinal cord dorsal horn. Subcutaneously injection of dexmedetomidine at the dose of 50 μg/kg at 30 min before plantar incision significantly attenuated remifentanil-induced mechanical and thermal hyperalgesia from 2 h to 48 h after infusion, and this was associated with reversal of up-regulated NR1 and NR2B subunits in both membrane fraction and total lysate as well as increased PKC and CaMKII expression in spinal cord dorsal horn. Furthermore, remifentanil incubation increased amplitude and frequency of NMDA receptor-induced current in dorsal horn neurons, which was dose-dependently attenuated by dexmedetomidine. These results suggest that dexmedetomidine can significantly ameliorate RIH via modulating the expression, membrane trafficking and function of NMDA receptors as well as PKC and CaMKII level in spinal dorsal horn, which present useful insights into the mechanistic action of dexmedetomidine as a potential anti-hyperalgesic agents for treating RIH.