The effects of intravenous dexmedetomidine on spinal anesthesia: comparision of different dose of dexmedetomidine

Opioid-sparing effect of erector spinae plane block and intravenous dexmedetomidine for obese patients with obstructive sleep apnea: A randomized controlled trial

OBJECTIVE

This study assessed the impact of erector spinae plane block (ESPB) and intravenous (IV) dexmedetomidine in reduction of perioperative opioid consumption following bariatric surgery and their impact on post-operative recovery, analgesia, and pulmonary functions.

DESIGN

A randomized controlled trial.

SETTING

Tanta University Hospitals, Tanta, Gharboa, Egypt.

PATIENTS

Forty obese patients with obstructive sleep apnea syndrome (OSAS), aged 20-55 years, and eligible for bariatric surgery were included.

INTERVENTIONS

Patients randomized into group I (received general anesthesia [GA] with opioid, sham ESPB, and IV normal saline) or group II (received GA [without opioid], ESPB [at T7 level] using 20 mL bupivacaine 0.25 percent and bolus IV dexmedetomidine 1 µg/kg and then 0.25 µg/kg/h).

MAIN OUTCOME MEASURES

Fentanyl consumption (primary outcome), sevoflurane consumption, recovery time, Visual Analog Scale (VAS), and pulmonary functions (secondary outcomes) were recorded.

RESULTS

Perioperative fentanyl (intraoperative, post-operative, and total) consumption and sevoflurane consumption were substantially lower in group II compared to group I (p = 0.010, <0.001, <0.001, and <0.001, respectively). Moreover, recovery time was shorter in group II (p < 0.001). At 2, 4, 8, and 24 hours after surgery, group I patients had VAS values considerably higher. Relative to preoperative values, pulmonary function did not significantly alter after surgery. Oxygen desaturation was significantly lower in group II (p = 0.001).

CONCLUSIONS

The ESPB with IV dexmedetomidine is advantageous for OSAS patients having bariatric surgery as it provides anesthesia and opioid-sparing effect with short recovery, adequate analgesia, and nonsignificant complications. Yet, it had no effect on post-operative pulmonary function.

The Effects of Premedication With Three Different Doses of Intravenous Dexmedetomidine on Spinal Anesthesia: A Randomized Comparative Study

BACKGROUND

Intravenous dexmedetomidine is one of the commonly preferred techniques for sedation during any regional procedure. However, only a very few studies compared the impact of different bolus doses during spinal anesthesia, and none for our geographical area.

MATERIALS AND METHODS

A total of 60 patients were allocated into either of the three groups (group I, II, III) to receive intravenous dexmedetomidine 0.5, 0.75, and 1 mcg/kg, respectively. The primary outcome was to compare the duration of sensory and motor blockade and the secondary outcomes were the level of sedation, hemodynamic stability, duration of analgesia, and the side effects, if any.

RESULTS

Two-dermatome regression time and the duration of motor block were significantly higher in groups II and III when compared to group I. However, the difference in duration of analgesia, Ramsay sedation scores, bradycardia, and hypotension was statistically insignificant between the groups.

CONCLUSION

Intravenous dexmedetomidine in doses of 0.75 and 1 mcg/kg significantly prolongs the two-dermatome regression time and duration of the motor block when compared to 0.5 mcg/kg dose. Hence, it is better to titrate the dose between 0.75 and 1 mcg/kg, as the administration of bolus intravenous Dex in doses ranging between 0.75 and 1 mcg/kg appears to provide adequate intraoperative block characteristics while maintaining hemodynamic stability without any significant respiratory depression or other adverse effects.

Very long-lasting spinal anesthesia with dexmedetomidine: A report of two cases

Spinal anesthesia usually lasts up to two hours, but an infusion of IV dexmedetomidine can prolong it to three to four hours. We report two cases where single spinal anesthesia with IV dexmedetomidine was maintained for more than six hours during tibia fracture surgery. The spinal anesthesia was maintained for 350 and 390 minutes without another medication, and the sensory level confirmed after the surgery was T10 and L1. Dexmedetomidine can very-prolong the duration of spinal anesthesia beyond what has been reported. However, longer infusion times can also result in longer recovery times.

Comparison of the effect of dexmedetomidine and midazolam under spinal anesthesia for cesarean delivery: a randomized controlled trial, single center study in South Korea

BACKGROUND

Cesarean section under spinal anesthesia may cause anxiety and hypotension. Administration of sedative drugs after delivery can diminish these side-effects, but may increase hemodynamic instability. We evaluated the effect of the administration of 0.7 μg/kg dexmedetomidine and compared it with that of 0.03 mg/kg midazolam for usefulness of sedation of the parturient after delivery during cesarean section.

METHODS

After obtaining written consent and the ethics board approval, 60 parturients aged 20-43 years who underwent elective cesarean delivery under spinal anesthesia were recruited. A total of 0.5% hyperbaric bupivacaine (8-10 mg) and intrathecal fentanyl (10 μg) was given to induce anesthesia. Parturients were then randomly allocated to receive either midazolam (0.03 mg/kg; group M) or dexmedetomidine 0.7 (μg/kg; group D) after delivery. The primary outcome measure was patient satisfaction score. Secondary outcomes included vital signs; vasopressor dosage; incidence of shivering, nausea, and vomiting; incidence of bradycardia; time to sensory and motor recovery; postoperative nausea and vomiting score; and postoperative pain visual analog scale at 6, 24, and 48 h.

RESULTS

Satisfaction scores for sedation were similar between the two groups. The systolic blood pressure, heart rate, oximetry saturation, and tympanic temperature were comparable between the two groups. The predicted mean systolic blood pressure of group D was 106.3 mmHg and that of group M was 107.5 mmHg. Both groups showed comparable adverse intraoperative and postoperative outcomes.

CONCLUSIONS

Dexmedetomidine and midazolam showed similar hemodynamic effects and patient satisfaction in parturients under spinal anesthesia.

Efficacy of dexmedetomidine versus midazolam when combined with butorphanol for sedation and analgesia during burn dressing changes: A randomized clinical trial

Objective: The aim of this study was to compare dexmedetomidine-butorphanol (DB) and midazolam-butorphanol (MB) combinations for sedation, and analgesia in burn patients undergoing dressing changes.

Methods: A total of 56 ASA I–II burn patients were included in this single-center randomized clinical trial. The ages of these patients were between 20 and 60 years. TBSA ranged from 10% to 50%. They were randomized to group DB and group MB during dressing change. In the DB group, each patient received a bolus dose of dexmedetomidine (0.5 μg kg−1) and intermittent boluses of butorphanol (20 μg kg−1). In the MB group, each patient received a bolus dose of midazolam (0.05 mg kg−1) and intermittent boluses of butorphanol (20 μg kg−1). The primary outcomes were sedation scores and pain scores. The second outcomes were vital signs, side effects, and butorphanol consumption.

Results: The sedation scores of these two groups did not differ significantly (p &gt; 0.05), and the pain scores of these groups were not significantly different (p &gt; 0.05). More patients had hypotension in the DB group than in the MB group (6 versus 0, p = 0.01), but the number of patients who had respiratory depression was higher in the MB group compared with the DB group (4 versus 0, p = 0.038). Butorphanol consumption in the MB group was higher than in the DB group (p = 0.025).

Conclusion: Dexmedetomidine is comparable to midazolam when combined with butorphanol in burn patients during dressing change. Compared with midazolam, it has the advantage of opioid-sparing effect.

Clinical Trial Registration: [http://www.chictr.org.cn/showproj.aspx&amp;proj=130622], identifier [ChiCTR2100049325].

Analgesic and hemodynamic effects of intravenous infusion of magnesium sulphate versus dexmedetomidine in patients undergoing bilateral inguinal hernial surgeries under spinal anesthesia: a randomized controlled study

BACKGROUND

Spinal anesthesia is commonly employed during inguinal hernial surgeries. Its short duration may, however, be considered a limitation, especially for bilateral hernial repair. The aim of this research is to investigate the analgesic and hemodynamic effects of intravenous infusion of both MgSO₄ and dexmedetomidine on patients undergoing bilateral inguinal hernia surgeries under spinal anesthesia.

METHODS

This study was a prospective, randomized, double-blinded controlled trail. It included 60 male patients who had been scheduled for bilateral elective inguinal hernia surgery under spinal anesthesia at Kasr Al-Aini hospital. Patients were randomly allocated to one of three groups (n = 20 each) to receive 50 mL of 0.9% saline intravenous infusion of either dexmedetomidine 0.5 μg.kg^-1. h^-1 (Group D) or magnesium sulphate 15 mg.kg^-1. h^-1 (Group M) or normal saline (Group S). The primary outcome of this study was set as the total duration of analgesia. Secondary outcomes were set as the onset and duration of sensory and motor blockade, perioperative hemodynamics, and the total 24-hour postoperative morphine consumption.

RESULTS

Durations of sensory and motor blockades as well as durations of analgesia were all significantly longer among patients in Group D (mean 2.2, 3.5, 5.8 hours respectively) and Group M (mean 2.2, 3.3, 5.2 hours respectively), in comparison to Group S (mean 1.5, 2.7, 3.9 hours respectively). No significant differences were found in systolic or diastolic arterial blood pressure, heart rate oxygen saturation, cardiac output, or stroke volume among the study groups. Seven patients in Group D and four patients in Groups M and S developed hypotension.

CONCLUSION

Intravenous infusion of either dexmedetomidine or MgSO₄ with spinal anesthesia effectively improves the quality of spinal anesthesia and prolongs the duration of postoperative analgesia and decreases the 24-hour postoperative morphine consumption. Results also demonstrated that the use of dexmedetomidine resulted in a slightly longer duration of analgesia, whilst the use of MgSO₄ resulted in slightly better hemodynamic stability.

The Effect of Different Doses of Intravenous Dexmedetomidine on the Properties of Subarachnoid Blockade: A Systematic Review and Meta-Analysis

Background

Dexmedetomidine is a sedative and analgesic medication which has gained an increased usage as an adjuvant to both general and regional anaesthesia in recent years. In this systematic review and meta-analysis, we examined the changes to the characteristics of subarachnoid block when accompanied with intravenous dexmedetomidine. Our aim is to evaluate the effects of different doses of intravenous dexmedetomidine on the sensory and motor blockade duration of a single shot spinal anaesthetic and the incidence of any associated side effects.

Methods

We searched published randomized clinical trials (RCTs) from January 1992 to April 2019 that investigated the use of IV dexmedetomidine with spinal anaesthesia. After considering our inclusion and exclusion criteria, we included 15 RCTs with 985 patients. We analyzed the duration of sensory and motor blockade and the related adverse effects in relation to different doses of IV dexmedetomidine.

Results

Intravenous dexmedetomidine, with loading dose of 1 mcg/kg, prolonged the sensory blockade duration of spinal anaesthesia by a mean difference of 49.6 min, P<0.001, and motor blockade duration by a mean difference of 44.7 min, P<0.001, while a loading dose of 0.5 mcg/kg prolonged the sensory blockade by a mean difference of 43.06 min, P<0.001, and motor blockade duration by a mean difference of 29.09 min, P<0.001. Dexmedetomidine-related side effects were higher in patients receiving larger doses; the incidence of bradycardia was higher (OR=3.53, P<0.001) and incidence of hypotension showed a 1.29 fold increase when compared to the control group (P=0.065).

Conclusion

The administration of intravenous dexmedetomidine in conjunction with spinal anaesthesia can significantly prolong the duration of both sensory and motor blockade. The use of larger loading doses of dexmedetomidine was associated with a larger side-effect profile with minimal beneficial changes when compared to lower loading doses.

Effect of intrathecal dexmedetomidine versus intravenous dexmedetomidine on subarachnoid anesthesia with hyperbaric bupivacaine

Background and Aim:

Alpha-2 agonists such as dexmedetomidine when given intravenously or intrathecally as an adjuvant potentiate subarachnoid anesthesia. We studied the difference in subarachnoid anesthesia when supplemented with either intrathecal or intravenous dexmedetomidine.

Material and Methods:

Seventy-five patients posted for lower limb and infraumbilical procedures were enrolled for a prospective, randomized, double-blind, placebo-controlled study and divided into three groups: Group B (n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%bupivacaine + 0.2 mL sterile water; Group B_DexIT (n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL (5 μg) dexmedetomidine; Group B_DexIV (n = 25) received intravenous dexmedetomidine 1 μg/kg in 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL sterile water. Onset and recovery from motor and sensory blockade, and sedation score were recorded. Onset of sensory and motor blockade was assessed using Kruskal–Wallis test, whereas 2-segment regression and recovery was analyzed using ANOVA and post hoc Tukey's test to determine difference between the three groups. P value <0.05 was considered statistically significant.

Results:

Although onset of sensory and motor block was similar in the three groups, motor recovery (modified Bromage scale 1) and two-segment sensory regression was prolonged in Group B_DexIT > Group B_DexIV > Group B (P < 0.001). Patients in Group B_DexIT and Group B_DexIV were sedated but easily arousable.

Conclusion:

Intrathecal dexmedetomidine prolongs the effect of subarachnoid anesthesia with arousable sedation when compared with intravenous dexmedetomidine.

Comparative analgesic efficacy of intravenous vs intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine in subarachnoid block for below knee orthopaedic surgery

Background and Aim:

Intrathecal and intravenous dexmedetomidine has been used as adjuvant in subarachnoid block [SAB]. The aim of this study was to compare the analgesic efficacy of intravenous vs intrathecal dexmedetomidine as adjuvant to intrathecal bupivacaine.

Methods:

Ninety patients, aged 20–60 years belonging to American Society of Anaesthesiologists (ASA) physical status I and II, scheduled for below knee orthopaedic surgeries under SAB were enrolled. In group I (n = 45) patients received intravenous dexmedetomidine 0.5 μg/kg in 100 mL 0.9% normal saline [NS] intravenous over a period of 15 minutes given 20 minutes before SAB. Subarachnoid block was given with intrathecal (IT) 0.5% bupivacaine (H) 12.5 mg (2.5 mL) with 0.3 mL of NS. Patients in group II (n = 45) received 100 mL of 0.9% NS over a period of 15 minutes given 20 minutes before subarachnoid block. SAB was given with intrathecal 0.5% heavy bupivacaine 12.5 mg with 3 μg of dexmedetomidine (0.3 mL). The primary outcome was duration of analgesia and rescue analgesic requirement, whereas secondary outcome included pain scores.

Results:

The duration of analgesia was prolonged in group II (median [IQR]: 5 (6–7.5) h than in group I (median[IQR]: 4[2–4.5] h, P = 0.000). Median dose of rescue analgesics over period of 24 hours was less in group II as compared to group I (median [IQR]:150 (75–150) mg vs 195 (150–225) mg, P = 0.000). VAS score was lower in group II till 12 h in the postoperative period (P = 0.00).

Conclusion:

Intrathecal dexmedetomidine is more efficacious as compared to intravenous dexmedetomidine, due to favourable outcomes in terms of increased duration of postoperative analgesia and reduced rescue analgesic requirement.

Intravenous Dexmedetomidine Has Synergistic Effect on Subarachnoid Block with Hyperbaric Bupivacaine

Objective

To assess the effect of intravenous dexmedetomidine on subarachnoid anesthesia with the help of hyperbaric bupivacaine when administered as a bolus or as an infusion.

Materials and methods

This randomized control trial was conducted at the Department of Anesthesia, Nishtar Hospital, Multan, Pakistan, from January 2017 to December 2018. Seventy patients were enrolled in the study. Patients were segregated into three groups. At the T10 level, a sensory blockade was noted. The motor blockade was also periodically measured until a modified Bromage score of three was achieved. The depth of sedation was measured with the help of the Ramsay Sedation Scale score. Oxygen saturation and other factors were also measured and recorded. Nausea, vomiting, diarrhea, and pruritus were the adverse effects noted during the study. To check and compare the statistical differences among the variables from different groups, the Chi-square test and analysis of variance test were performed. A probability (p) value of <.05 was considered statistically significant.

Results

The duration of the sensory blockade was shortest in the control group receiving only bupivacaine (Group B) and longest in the group receiving bupivacaine plus dexmedetomidine as a single bolus (Group BDexB; p: <.001). The time of complete sensory and motor recovery was longest in Group BDexB and shortest in Group B. The difference was statistically significant (p: <.001). The Ramsay score was >2 (i.e., 3 or 4) in five patients from Group B, 19 from Group BDexB, and 17 from the group receiving intrathecal bupivacaine plus dexmedetomidine as an infusion (Group BDexI). Between these groups, a statistically significant difference was found (p: <.001).

Conclusions

Intravenous administration of dexmedetomidine as either a bolus or infusion prolonged the duration of the sensory and motor blockade.

Sedation with dexmedetomidine prolongs the analgesic duration of brachial plexus block: a randomised controlled trial

PURPOSE

Dexmedetomidine, an alpha 2 receptor agonist, prolongs nerve block duration when administered in conjunction with peripheral nerve blocks. We hypothesised that sedation with dexmedetomidine could also significantly prolong the analgesic duration of brachial plexus block (BPB) during orthopaedic surgery on the upper extremities.

MATERIALS AND METHODS

One hundred and two patients received upper extremity surgery under BPB. The patients were randomly sedated with dexmedetomidine (D group) or midazolam (M group) following BPB using 25 mL of local anaesthetics (1:1 mixture of 1% lidocaine and 0.75% ropivacaine). Adequate sedation was evaluated with the modified Ramsay Sedation Scale. Primary outcome was measured as the time the patient first requested analgesic via a patient-controlled analgesia device. Total opioid consumption during the first 24 post-operative hours was also measured as secondary outcomes.

RESULTS

Time to first request for analgesia (mean ± standard deviation) was significantly longer in the D group (616.9 ± 158.2 min) than in the M group (443.7 ± 127.2 min) (P < 0.001, Mean difference [95% CI] 173.2 [114.8-231.5] min). Total opioid consumption were significantly lower in the D group (fentanyl equivalent, 280.0 μg [171.3;374.0] vs. 363.9 μg [208.3;570.1], P = 0.01). Although patients in the D group showed deeper sedation over time (P < 0.001), PACU stay time was only slightly extended in D group (5.2 [1.2-9.2] min). Perioperative complications did not differ in the two groups.

CONCLUSION

Sedation with dexmedetomidine not only prolongs analgesic duration of BPB, but also reduces total opioid consumption during the first 24 post-operative hours.

Comparison of Intravenous Bolus and Infusion of Dexmedetomidine on Characteristics of Subarachnoid Block

Aims:

Dexmedetomidine is very dynamic drug, used for analgesia, sedation, blunting the laryngoscopic responses and as adjuvants in regional anesthesia. Studies have shown that intravenous (iv) dexmedetomidine given during spinal anesthesia increases the quality of subarachnoid block (SAB). In this study, we compare the two iv regimen of dexmedetomidine on analgesic effect of spinal anesthesia. One is bolus dose of dexmedetomidine and other is infusion during the surgery, both given after induction of spinal anesthesia.

Subjects and Methods:

Sixty American Society of Anesthesiologists I and II patients scheduled to undergo surgeries under SAB were randomly allocated into two groups namely B and I. After SAB with 3.0 ml of bupivacaine 0.5% heavy, Group B received 0.5 μg/kg of dexmedetomidine bolus over 15 min, Group I received 0.5 μg/kg/h of dexmedetomidine infusion until the end of surgery.

Statistical Analysis Used:

All parametric data were statistically analyzed using Student's t-test and nonparametric data analyzed using Chi-square test and Fischer exact test as appropriate. P < 0.05 was considered as statistically significant. Statistical analysis was performed using the SPSS.

Results:

Time to reach desired level T₁₀ was quick in Group B compared to Group I. Regression of sensory and motor was prolonged in Group I compared to Group B. Total duration of analgesia was significantly prolonged in Group I 230.39 ± 16.20 compared to Group B 196.01 ± 14.32 and the difference is statistically significant (P = 0.0001). Both groups had Ramsay sedation score of 3 which lasted for 45 min in Group B while it was maintained in Group I. Side effects profile of both groups was comparable with few incidence of bradycardia and hypotension in both groups requiring treatment.

Conclusions:

We conclude that the continuous infusion of dexmedetomidine after SAB results in prolonged analgesia than just a bolus dose. Therefore, we suggest use of the maintenance dose of iv dexmedetomidine after SAB for prolonging the duration and achieving adequate sedation

Clinical evaluation of combination of dexmedetomidine and midazolam vs. dexmedetomidine alone for sedation during spinal anesthesia

Background

Dexmedetomidine is a useful sedative agent for spinal anesthesia. However, it has been reported to decreases heart rate in a dose-dependent manner. In the present study, we compared the bolus dose of midazolam and bolus loaded dexmedetomidine over 10 min to determine additional sedation methods.

Methods

A total of 100 patients who were classified as American Society of Anesthesiologists physical status I-II undergoing spinal anesthesia were randomly divided into two groups. In the combination of midazolam and dexmedetomidine group (group MD), 10 min after bolus loading of 0.05 mg/kg midazolam, 0.5 μg/kg/h dexmedetomidine was infused. In the dexmedetomidine group (group D), 1 μg/kg bolus dose of dexmedetomidine was infused over 10 min, and then 0.5 μg/kg/h dexmedetomidine was infused continuously.

Results

At 10 min, the sedation depth of the two groups was approximately the same. In both groups, the bispectral index (BIS) was within the optimal range of 55-80 and the Ramsay Sedation Scale score was within the optimal range of 3-5. Both patient and surgeon satisfaction with sedation did not differ between groups. At 10 min, heart rate (beats/min) was significantly lower (P < .01) in group D and mean blood pressure (mm Hg) was significantly lower (P < .01) in group MD. The prevalence of bradycardia (P = .714), hypotension (P = .089), and hypoxia (P = .495) did not differ statistically between the two groups.

Conclusions

Midazolam bolus and dexmedetomidine continuous infusion may be a useful additional sedation method for patients who have severe bradycardia.

Dexmedetomidine as a Supplement to Spinal Anesthesia Block: A Case Report of Three Infants

We report a novel use for dexmedetomidine as a supplemental intravenous or intranasal sedative for spinal anesthesia in infants. The children were 1, 2, and 9 months old having either inguinal hernia repair or circumcision. None of them experienced clinically relevant hemodynamic changes or apnea. Pain scores were zero throughout the postoperative period.

The timing of administration of intravenous dexmedetomidine during lower limb surgery: a randomized controlled trial

Background

Dexmedetomidine, a selective alpha-2 agonist, has sedative, analgesic, and anxiolytic effects without respiratory depression. Dexmedetomidine can cause a biphasic cardiovascular response, and induce transient hypertension. Hypotension is a common complication of spinal anesthesia. Decreasing anxiety of patients before procedure is important for high quality of procedure. This study aimed to compare the incidence of hypotension and patients’ anxiety and comfort levels when dexmedetomidine was intravenously administered before and after spinal anesthesia.

Methods

Seventy-four patients with American Society of Anesthesiologists physical status classification I or II were randomly allocated into two groups. Spinal anesthesia was performed using 12 mg of 0.5% heavy bupivacaine. In Group A, 1 μg/kg of dexmedetomidine was intravenously administered for 10 min, followed by the maintenance infusion of dexmedetomidine 0.2 μg/kg/hr after 5 min of intrathecal bupivacaine injection. Patients in Group B received same dose of dexmedetomidine by intravenous administration before 5 min of intrathecal bupivacaine injection. Perioperative vital signs, anxiety (using the Spielberger’s State-Trait Anxiety Inventory) and comfort (using the numerical rating scale) were evaluated.

Results

The incidence of hypotension was significantly lower in Group A (16.1%) than in Group B (48.4%) during infusion of dexmedetomidine (p = 0.01). The need for treatment of hypotension is higher in Group B than Group A (p = 0.02). The incidence of bradycardia and desaturation did not significantly differ between the two groups. There were no statistically significant differences regarding the patients’ anxiety and comfort.

Conclusions

Hypotension is more frequently occurred, and the treatment of hypotension is more needed in Group B. The intravenously administration of dexmedetomidine before spinal anesthesia has no advantages in hemodynamic status and patients’ comfort compared to that after spinal anesthesia during lower limb surgery.

Trial registration

ClinicalTrials.gov number, NCT02155010. Retrospectively registered on May 22, 2014.

Dexmedetomidine combined with midazolam vs. dexmedetomidine alone for sedation during spinal anesthesia

Background

Dexmedetomidine is a useful sedative agent for spinal anesthesia. However, it has been reported that dexmedetomidine decreases heart rate in a dose-dependent manner. In the current study, we compared the administration of a bolus dose of midazolam and bolus loading of dexmedetomidine over 10 min with the goal of identifying an additional method of sedation.

Methods

Ninety patients classified as American Society of Anesthesiologists physical status I–II who were undergoing spinal anesthesia were divided into two groups. In the midazolam and dexmedetomidine combined group (group MD), 10 min after bolus loading of 0.05 mg/kg midazolam, 0.5 µg/kg/h dexmedetomidine was continuously infused. In the dexmedetomidine group (group D), 1 µg/kg dexmedetomidine was infused over 10 min, and then 0.5 µg/kg/h dexmedetomidine was continuously infused.

Results

At 10 min, the sedation depth of the two groups was almost equal. In both groups, the bispectral index was within the optimal score range of 55–80 and the Ramsay Sedation Scale score was within the optimal range of 3–5. Satisfaction with sedation for both patient and surgeon did not differ between the two groups. At 10 min, heart rate was significantly lower (P < 0.010) in group D and mean blood pressure was significantly lower (P < 0.010) in group MD. The prevalence of bradycardia, hypotension, and hypoxia did not differ statistically between the two groups (P = 0.714, P = 0.089, P = 0.495, respectively).

Conclusions

Midazolam bolus and dexmedetomidine continuous infusion (the regimen of group MD) may be an additional sedation method for patients who have severe bradycardia.