Preoperative Dexmedetomidine and intraoperative bradycardia in laparoscopic cholecystectomy: meta-analysis with trial sequential analysis

Randomized controlled trial on effect of different routes of dexmedetomidine on Haemodynamics in patients undergoing saphenectomy under epidural anaesthesia

The effect of epidural infusion of dexmedetomidine on haemodynamics is unclear. This study aimed to explore the effects of epidural or intravenous infusion of dexmedetomidine on haemodynamics during lower extremity varicose veins surgery (saphenectomy) under epidural anaesthesia. Ninety patients were randomly allocated to three groups: ED group (epidural: 0.59% ropivacaine plus 0.5 µg/kg dexmedetomidine, intravenous: normal saline), VD group (epidural: 0.59% ropivacaine plus normal saline, intravenous: 0.5 µg/kg dexmedetomidine), or NS group (epidural: 0.59% ropivacaine plus normal saline, intravenous: normal saline). The primary outcome was the systolic blood pressure (SBP) at before anaesthesia (T0) and at 5 (T1), 15 (T2), and 30 min (T3) and 1 (T4), 2 (T5), 4 (T6), 6 (T7), and 8 h (T8) after dexmedetomidine infusion. The secondary outcomes were diastolic blood pressure (DBP) and heart rate (HR) at T0 - 8, plasma norepinephrine (NE), myocardial oxygen consumption (MVO2) and anesthesia efficacy. Adverse reactions and other general data were also recorded. Compared with those in the NS group, the SBP at T3 - 7 and DBP at T4 - 5,7 were significantly lower in the ED group (P = 0.008, 0.001, 0.001, 0.001, 0.038 and P = 0.017, 0.006, 0.044, respectively), and the SBP and DBP at T1 - 8 were lower in the VD group (P < 0.001, 0.001, 0.001, 0.001, 0.004 and P < 0.001, 0.001, 0.001, 0.002, 0.001, 0.001, 0.001, 0.036, respectively). The SBP and DBP at T1 - 2 in the ED group were greater than those in the VD group (P = 0.021, 0.01 and P = 0.001, 0.011, respectively). The HR at T3 - 4,6-7 was lower in the ED group than in the NS group (P < 0.001, 0.021, 0.002, 0.004, respectively). Compared with that in the VD group, the HR in the ED group at T7 was significantly lower (P < 0.001). Anaesthesia efficiency was improved in the ED group compared with VD and NS groups. The incidence of hypotension was lower in the ED group than in the VD group (P = 0.003). The combination of 0.5 µg/kg dexmedetomidine and 0.59% ropivacaine for epidural anaesthesia provides more stable haemodynamics with a lower incidence of hypotension and improved efficiency of epidural anaesthesia in patients undergoing saphenectomy.

Hemodynamic instability following intravenous dexmedetomidine infusion for sedation under brachial plexus block: Two case reports

BACKGROUND

Dexmedetomidine (DMED) is frequently used as a sedative in several medical fields. The benefits of DMED include enhanced quality of regional anesthesia, prolonged analgesia, and postoperative opioid-sparing when administered intravenously or perineurally in combination with regional anesthesia. Severe hemodynamic complications, such as profound bradycardia and hypotension, can occur after DMED administration in critically ill patients or overdosage; however, there are few reports of complications with DMED administration following brachial plexus block (BPB).

CASE SUMMARY

We present two cases of hemodynamic instability that occurred following the initial loading of DMED under supraclavicular BPB. A healthy 29-year-old man without any medical history showed profound bradycardia after receiving a loading dose of DMED 0.9 μg/kg for 9 min. DMED administration was promptly stopped, and after receiving a second dose of atropine, the heart rate recovered. A 62-year-old woman with a history of cardiomyopathy became hypotensive abruptly, requiring the administration of inotrope and vasopressors after receiving a reduced loading dose of 0.5 μg/kg for 10 min. Half of the recommended loading dose of DMED was administered due to the underlying heart dysfunction. Decreased blood pressure was maintained despite the intravenous administration of ephedrine. With continuous infusion of dopamine and norepinephrine, the vital signs were maintained within normal ranges. Inotropic and vasopressor support was required for over 6 h after the initial loading dose of DMED.

CONCLUSION

DMED administration following BPB could trigger hemodynamic instability in patients with decreased cardiac function as well as in healthy individuals.

Efficacy and safety of intravenous dexmedetomidine as an adjuvant to general anesthesia in gynecological surgeries: A systematic review and meta-analysis of randomized controlled trials

This study investigated the efficacy and safety of intravenous dexmedetomidine as an adjuvant to general anesthesia in patients undergoing gynecological surgery. We systemically searched for randomized controlled trials (RCTs), and performed a meta-analysis on studies that met the inclusion criteria. The primary outcomes were postoperative nausea and vomiting (PONV), bradycardia, hypotension, and 24 h opioid consumption. The secondary outcomes include postoperative shivering, postoperative pain score, intraoperative anesthetic consumption, extubation time, postoperative sedation, and the time to first flatus. Twenty-five RCTs were included in this study. Meta-analysis showed that intravenous dexmedetomidine significantly reduced the risk of PONV (RR, 0.57 [0.47, 0.68]) and postoperative shivering (RR: 0.31 [0.22, 0.42]), 24 h opioid consumption (Mean Difference: - 4.85 mg [-8.60, -1.11]) and postoperative pain score within 24 h. However, these benefits were at the cost of increased bradycardia (RR, 3.21 [2.41, 4.28]) and hypotension (RR, 2.17 [1.50, 3.14]). Notably, no serious adverse effects were reported in any of the included studies. Thus, our study showed that intravenous dexmedetomidine provided significant antiemetic and anti-shivering effects and moderate analgesic effects in patients that underwent gynecological surgery. However, its benefits should be weighed against the significantly increased risk of bradycardia and hypotension.

Impact of pharmacological interventions on intrapulmonary shunt during one-lung ventilation in adult thoracic surgery: a systematic review and component network meta-analysis

BACKGROUND

Intrapulmonary shunt is a major determinant of oxygenation in thoracic surgery under one-lung ventilation. We reviewed the effects of available treatments on shunt, Pao₂/FiO₂ and haemodynamics through systematic review and network meta-analysis.

METHODS

Online databases were searched for RCTs comparing pharmacological interventions and intrapulmonary shunt in thoracic surgery under one-lung ventilation up to March 30, 2022. Random-effects (component) network meta-analysis compared 24 treatments and 19 treatment components. The Confidence in Network Meta-Analysis (CINeMA) framework assessed evidence certainty. The primary outcome was intrapulmonary shunt fraction during one-lung ventilation.

RESULTS

A total of 55 RCTs were eligible for systematic review (2788 participants). The addition of N₂O (mean difference [MD]=-15%; 95% confidence interval [CI], -25 to -5; P=0.003) or almitrine (MD=-13%; 95% CI, -20 to -6; P<0.001) to propofol anaesthesia were efficient at decreasing shunt. Combined epidural anaesthesia (MD=3%; 95% CI, 1-5; P=0.005), sevoflurane (MD=5%; 95% CI, 2-8; P<0.001), isoflurane (MD=6%; 95% CI, 4-9; P<0.001), and desflurane (MD=9%; 95% CI, 4-14; P=0.001) increased shunt vs propofol. Almitrine (MD=147 mm Hg; 95% CI, 58-236; P=0.001), dopexamine (MD=88 mm Hg; 95% CI, 4-171; P=0.039), and iloprost (MD=81 mm Hg; 95% CI, 4-158; P=0.038) improved Pao₂/FiO₂. Certainty of evidence ranged from very low to moderate.

CONCLUSIONS

Adding N₂O or almitrine to propofol anaesthesia reduced intrapulmonary shunt during one-lung ventilation. Halogenated anaesthetics increased shunt in comparison with propofol. The effects of N₂O, iloprost, and dexmedetomidine should be investigated in future research. N₂O results constitute a research hypothesis currently not backed by any direct evidence. The clinical availability of almitrine is limited.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42022310313.

Effects of Dexmedetomidine on Basic Cardiac Electrophysiology in Adults; a Descriptive Review and a Prospective Case Study

Dexmedetomidine (DEX) is a commonly used sedative agent with no or minimal effects on breathing. DEX may also be beneficial in myocardial protection. Since the mechanisms of cardiac effects are not well known, we carried out a descriptive review and examined the effects of DEX on myocardial electrical conduction in a prospective and controlled manner. For the review, clinical studies exploring DEX in myocardial protection published between 2020-2022 were explored. A case study included 11 consecutive patients at a median (range) age of 48 (38-59), scheduled for elective radiofrequency ablation of paroxysmal atrial fibrillation. A bolus dose of DEX 1 µg/kg given in 15 min was followed by a continuous infusion of 0.2-0.7 µg/kg/h. Direct intracardiac electrophysiologic measurements, hemodynamics and oxygenation were measured before and after the DEX bolus. Experimental studies show that DEX protects the heart both via stabilizing cardiac electrophysiology and reducing apoptosis and autophagy after cell injury. The clinical evidence shows that DEX provides cardiac protection during different surgeries. In a clinical study, DEX increased the corrected sinus node recovery time, prolongated the atrioventricular (AV) nodal refractory period and cycle length producing AV nodal Wenckebach retrograde conduction block. DEX has a putative role in organ protection against hypoxic, oxidative and reperfusion injury. DEX slows down the firing of the sinus node and prolongs AV refractoriness.