Effects of remimazolam combined with remifentanil on quality of recovery after ambulatory hysteroscopic surgery: a prospective, observational study.

BACKGROUND: Remimazolam, a new benzodiazepine, is known for its quick onset of effects and recovery time. Recently, it has been licensed for general anesthesia and sedation in Korea and its use is increasing in other countries. However, less is known about its effect on postoperative recovery. We used a patient-reported outcome questionnaire to examine the effect of remimazolam on postoperative recovery. METHODS: Patients who underwent hysteroscopy on day surgery basis were administered an induction dose of remimazolam 6 mg/kg/h followed by a maintenance dose of 1-2 mg/kg/h. After surgery, the translated Korean version of 15-item Quality of Recovery scale (QoR-15K) including post-discharge nausea and vomiting (PDNV) and/or pain, was surveyed 24 h after surgery to evaluate patient recovery. RESULTS: Total of 38 patients were enrolled in this prospective, observational study. All patients successfully completed QoR-15K. Only one patient scored low for moderate pain and PDNV. On average, patients scored 9 and above for all QoR-15K items except for moderate pain (8.66 ± 1.68). When QoR-15K items were grouped into dimensions, all dimensions scored an average of 9 or higher on a 10-point scale. In addition, 19 out of 38 patients gave score range of 148 to 150 out of possible 150. CONCLUSIONS: Psychometric evaluation based on postoperative QoR-15K among patients receiving remimazolam shows satisfactory patient recovery profiles without significant pain or PDNV. Considering its effectiveness and safety, remimazolam could be one of useful agents for general anesthesia of day surgery in terms of postoperative recovery.

Reduced side effects and improved pain management by continuous ketorolac infusion with patient-controlled fentanyl injection compared with single fentanyl administration in pelviscopic gynecologic surgery: a randomized, double-blind, controlled study.

BACKGROUND: A combination of opioids and adjunctive drugs can be used for intravenous patient-controlled analgesia (PCA) to minimize opioid-related side effects. We investigated whether two different analgesics administered separately via a dual-chamber PCA have fewer side effects with adequate analgesia than a single fentanyl PCA in gynecologic pelviscopic surgery. METHODS: This prospective, double-blind, randomized, and controlled study included 68 patients who underwent pelviscopic gynecological surgery. Patients were allocated to either the dual (ketorolac and fentanyl delivered by a dual-chamber PCA) or the single (fentanyl alone) group. Postoperative nausea and vomiting (PONV) and analgesic quality were compared between the two groups at 2, 6, 12, and 24 h postoperatively. RESULTS: The dual group showed a significantly lower incidence of PONV during postoperative 2-6 h (P = 0.011) and 6-12 h (P = 0.009). Finally, only two patients (5.7%) in the dual group and 18 (54.5%) in the single group experienced PONV during the entire postoperative 24 h and could not maintain intravenous PCA (odds ratio: 0.056, 95% CI [0.007, 0.229], P < 0.001). Despite the administration of less fentanyl via intravenous PCA during the postoperative 24 h in the dual group than in the single group (66.0 ± 77.8 vs. 383.6 ± 70.1 µg, P < 0.001), postoperative pain had no significant intergroup difference. CONCLUSIONS: Two different analgesics, continuous ketorolac and intermittent fentanyl bolus, administered via dual-chamber intravenous PCA, showed fewer side effects with adequate analgesia than conventional intravenous fentanyl PCA in gynecologic patients undergoing pelviscopic surgery.

Effects of magnesium sulphate on neostigmine-induced recovery from moderate neuromuscular blockade with rocuronium: a randomized controlled trial.

Magnesium enhances the effects of neuromuscular blocking agents. However, there is a paucity of evidence demonstrating possible effects of magnesium on neostigmine-induced recovery from neuromuscular blockade with rocuronium. This study compared the profiles of recovery from neuromuscular blockade between groups treated with magnesium (Group M) and placebo controls (Group C). Sixty-four patients were randomly allocated to Group M or Group C. Patients in Group M received a loading dose of 50 mg/kg magnesium and continuous infusion of 15 mg/kg/hr. Patients in Group C received a comparable amount of saline. Rocuronium at 0.6 mg/kg was used for tracheal intubation and 0.1 mg/kg of rocuronium was additionally administered to maintain train-of-four (TOF) status of 2-3 during surgery. At the end of surgery, neostigmine (50 µg/kg) plus glycopyrrolate (10 µg/kg) were administered, and the recovery time for TOF ratios of 0.7, 0.8, and 0.9 was measured. The primary outcome was the time from neostigmine administration to recovery with a TOF ratio of 0.9. In addition, rocuronium onset time (time from administration of rocuronium to 95% suppression of the first TOF twitch response), additional requirements for rocuronium and spontaneous recovery period (the time from administration of rocuronium to reappearance of the first TOF twitch response) were also measured. Neostigmine-induced recovery time was comparable between Group M and Group C (10.6 ± 4.3 vs. 9.1 ± 5.0 min, respectively, p = 0.22). The rocuronium onset time was shorter in Group M, and the spontaneous recovery period was longer in Group M. The amount of additional rocuronium administered was 27% lower in Group M, but this difference was not significant. Magnesium was not shown to prolong neostigmine-induced recovery time from neuromuscular blockade with rocuronium, however, it enhanced the clinical effects of rocuronium.

Trends in Perioperative Magnesium Sulfate Use in Patients Who Underwent Major Cancer Surgery: A Retrospective Population-Based Cohort Study in South Korea.

INTRODUCTION: Magnesium sulfate is a potential anesthetic adjunct in cancer surgery. However, no definite consensus exists on the use of magnesium sulfate in patients undergoing major cancer surgery. OBJECTIVE: This study aimed to examine the trends and factors associated with magnesium sulfate administration in patients who underwent major cancer surgery in South Korea. MATERIALS AND METHODS: In this retrospective and population-based cohort study, we used 5-year health data that were extracted from the National registration database in South Korea from January 1, 2016 to December 31, 2020. All adult patients who underwent major cancer surgery during 2016-2020 in South Korea were included. RESULTS: In total, 253,538 patients were included. Among these patients, 6.6% (16,708/253,538) were administered magnesium sulfate during major cancer surgery. In multivariable logistic regression modeling, older age (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.02-1.02; P < .001), esophageal cancer surgery (vs lung cancer surgery [OR, 3.04; 95% CI, 2.80-3.30; P < .001]), increased Charlson comorbidity index score (OR, 1.03; 95% CI, 1.02-1.03; P < .001), mild-to-moderate disability (OR, 1.08; 95% CI, 1.03-1.14; P = .003), and severe disability (OR, 1.16; 95% CI, 1.05-1.27; P = .003) were associated with a higher incidence of perioperative magnesium sulfate administration for major cancer surgery. Video-assisted thoracoscopic surgery or laparoscopy (OR, .57; 95% CI, .55-.59; P < .001) and propofol-based total intravenous anesthesia (OR, .86; 95% CI, .82-.89; P < .001) were associated with a lower incidence of perioperative Mg sulfate administration for major cancer surgery. CONCLUSIONS: In South Korea, 6.6% of the patients who underwent major cancer surgery were administered magnesium sulfate during surgery. Certain factors, such as old age, thoracic cancer surgery, open laparotomy or thoracotomy, greater comorbid status, and inhalation anesthesia, were potentially associated with magnesium sulfate administration in patients undergoing major cancer surgery.

The Effect of Peripheral Nerve Block on Postoperative Delirium in Older Adults Undergoing Hip Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

This meta-analysis aimed to determine whether peripheral nerve blocks (PNB) reduce postoperative delirium (POD) in elderly patients undergoing hip surgery. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022328320). The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for randomized controlled trials (RCTs) on 26 April 2022. A total of 19 RCTs with 1977 participants were included. Perioperative PNB lowered the POD incidence on the third postoperative day (OR: 0.59, 95% CI [0.40 to 0.87], p = 0.007, I2 = 35%), in patients without underlying cognitive impairment (OR: 0.47, 95% CI [0.30 to 0.74], p = 0.001, I2 = 30%), and when a fascia iliaca compartment block (OR: 0.58, 95% CI [0.37 to 0.91], p = 0.02, I2 = 0%) or a femoral nerve block (OR: 0.33, 95% CI [0.11 to 0.99], p = 0.05, I2 = 66%) were performed. The pain score was also reduced (SMD: -0.83, 95% CI [-1.36 to -0.30], p = 0.002, I2 = 95%) after PNB. Perioperative PNB can lower the POD incidence and pain scores up to the third postoperative day. However, considering the wide variety of PNBs performed, more trials are needed to identify the effects of each PNB on POD.

Effects of Earmuffs and Eye Masks on Propofol Sedation during Spinal Anesthesia for Orthopedic Surgery: A Randomized Controlled Trial.

Intravenous sedative drugs are commonly administered during regional anesthesia. However, reducing the excessive use of sedatives while providing adequate sedation is important from the clinical perspective, since the use of sedatives can cause considerable complications. We hypothesized that the application of earmuffs and eye masks would help reduce the sedative dose required to maintain proper sedation by blocking external stimuli. Patients who underwent orthopedic surgery under spinal anesthesia were randomly allocated to the control (no intervention) or intervention group (wearing earmuffs and eye masks). Intravenous sedation was administered using target-controlled infusion of propofol. The target concentration was controlled to maintain a Modified Observer's Assessment of Alertness and Sedation score of 3 or 4. The primary outcome was the intraoperative propofol requirement. We also investigated the incidence of apnea, and patient satisfaction. Propofol requirement was significantly lower in the intervention group than that in the control group (2.3 (2.0-2.7) vs. 3.1 (2.7-3.4) mg·kg-1·h-1; p < 0.001). Intraoperative apnea occurred less frequently (p = 0.038) and patient satisfaction was higher (p = 0.002) in the intervention group compared to the control group. This study demonstrated that the use of earmuffs and eye masks during sedation was associated with lower propofol requirement and improved sedation quality.

Postoperative Delirium after Dexmedetomidine versus Propofol Sedation in Healthy Older Adults Undergoing Orthopedic Lower Limb Surgery with Spinal Anesthesia: A Randomized Controlled Trial.

BACKGROUND: Delirium is a critical postoperative complication in older patients. Based on the hypothesis that intraoperative dexmedetomidine sedation would lower postoperative delirium than propofol sedation would, the authors compared the incidence of postoperative delirium in older adults, using the mentioned sedatives. METHODS: This double-blinded, randomized controlled study included 748 patients, aged 65 yr or older, who were scheduled for elective lower extremity orthopedic surgery, between June 2017 and October 2021. Patients were randomized equally into two groups in a 1:1 ratio according to the intraoperative sedative used (dexmedetomidine vs. propofol). The postoperative delirium incidence was considered the primary outcome measure; it was determined using the confusion assessment method, on the first three postoperative days. The mean arterial pressure and heart rate were evaluated as secondary outcomes. RESULTS: The authors enrolled 732 patients in the intention-to-treat analyses. The delirium incidence was lower in the dexmedetomidine group than in the propofol group (11 [3.0%] vs. 24 [6.6%]; odds ratio, 0.42; 95% CI, 0.201 to 0.86; P = 0.036). During sedation, the mean arterial pressure (median [interquartile range] mmHg) was higher in the dexmedetomidine group (77 [71 to 84]) than in the propofol group (74 [69 to 79]; P < 0.001); however, it significantly fell lower (74 [68 to 80]) than that of the propofol group (80 [74 to 87]) in the postanesthesia care unit (P < 0.001). Lower heart rates (beats/min) were recorded with the use of dexmedetomidine than with propofol, both during sedation (60 [55 to 66] vs. 63 [58 to 70]) and in the postanesthesia care unit (64 [58 to 72] vs. 68 [62-77]; P < 0.001). CONCLUSIONS: Dexmedetomidine showed a lower incidence of postoperative delirium than propofol in healthy older adults undergoing lower extremity orthopedic surgery.

Ultrasound assessment of residual gastric volume in older adults undergoing staged-bilateral total knee arthroplasty after consuming carbohydrate-containing fluids: a prospective observational study.

BACKGROUND: We compared preoperative residual gastric volume (GV) between the first and second stages of total knee arthroplasty (TKA) in older adults after drinking carbohydrate-containing fluid 2 h prior to surgery. METHODS: In this study, 36 patients, aged > 65 years, scheduled for staged bilateral TKA with one-week interval, were enrolled. The patients consumed 400 ml of carbohydrate-containing fluid 2 h prior to surgery. Before the induction of spinal anesthesia, the gastric antral cross-sectional area was measured at the first and second TKA using ultrasound, and the residual GV was calculated. The primary outcome was the residual GV. Qualitative GV (grades 0, 1, and 2) and analgesic consumption after the first TKA were assessed as secondary outcomes. RESULTS: The GV (median [Q1, Q3]) was greater in the second-stage TKA (41.1 [22.5, 62.8] ml) than in the first-stage TKA (10.3 [0.0, 27.1] ml) (P < 0.001). In the qualitative assessment, the distribution was not different between the two stages of TKA (P = 0.219) and only one patient showed grade 2 gastric content in the second TKA. When opioid consumption was converted to an equivalent dose of morphine, an average of 53.9 mg of morphine was required after the first TKA. CONCLUSIONS: Residual GV after drinking carbohydrate-containing fluid differed according to the stage of TKA, showing a larger residual GV in the second TKA than in the first one. In older adults scheduled to undergo bilateral staged TKA, caution is required in preoperative fasting practice, especially in second-stage surgery.

The Involvement of the Hypothalamus-Pituitary-Adrenal Axis in the Development of Hyperalgesia during the Early Postoperative Period.

INTRODUCTION: Hyperalgesia frequently occurs after surgery and is associated with adverse effects on surgical outcomes. Thus, we aimed to examine whether the hypothalamus-pituitary-adrenal (HPA) axis function after surgery is involved in the development of postoperative hyperalgesia. METHODS: Surgery- and pain-related variables were measured 24 and 48 h after the first and second total knee arthroplasties (TKAs) in postmenopausal patients undergoing 1-week-interval staged bilateral TKA. Two sets of saliva samples were consecutively collected from patients before (pre-T1) and 1 week after (post-T1) the first TKA (n = 69). HPA axis function was analyzed in a subgroup of 20 patients with a typical cortisol awakening response (CAR) in both the sets of saliva samples. RESULTS: Surgery-related variables were comparable between the first and second TKAs. However, pain-related variables (pain ratings and the amount of opioid analgesics consumed) were greater after the second than the first TKA. Cortisol and dehydroepiandrosterone (DHEA) secretion during the post-awakening period (CARauc and Daucawk, respectively) was higher at post-T1 than at pre-T1, but the molar CARauc/Daucawk ratio was comparable between the time points examined. No relationship was observed between the pre-T1 CARauc and pain ratings after the first TKA. However, post-T1 CARauc showed a positive correlation with pain ratings after the second TKA. Postoperative pain ratings were negatively correlated with Daucawk and positively correlated with the molar CARauc/Daucawk ratio at all examined time points. DISCUSSION/CONCLUSION: The results suggest that adrenocortical steroidogenic activity favoring the production of cortisol over DHEA after surgery may contribute to the development of hyperalgesia during the early postoperative period.

Incidence of ionized hypomagnesemia in adult patients undergoing noncardiac major surgery: a prospective observational trial

Background: The present study aimed to investigate the incidence of preoperative ionized hypomagnesemia and compare with that of total hypomagnesemia. Methods: This prospective observational study included 536 patients aged >20 years who were scheduled for elective surgery. Total and ionized magnesium levels were evaluated before and after the surgery. Based on these levels, patients were classified into the following groups: ionized hypo- (<0.42 mmol/L), normo- (0.42-0.59 mmol/L) and hypermagnesemia (>0.59 mmol/L), as well as total hypo- (<1.9 mg/dL[0.78 mmol/L]), normo- (1.9-2.7 mg/dL[0.78-1.11 mmol/L]) and hypermagnesemia (>2.7 mg/dL [1.11 mmol/L]). The primary objective was to establish the incidence of preoperative ionized hypomagnesemia. Results: There was a marked difference between the incidence of preoperative ionized and total hypomagnesemia (28% vs. 19%; p<0.001). The postoperative values of ionized magnesium, ionized calcium, and albumin were significantly lower than the respective preoperative values (p<0.001 for all three variables). Conclusion: The incidence of hypomagnesemia, determined by ionized magnesium concentration, was higher than that determined by total magnesium concentration.

Total intravenous anesthesia induced and maintained by a combination of remimazolam and remifentanil without a neuromuscular blocking agent: a prospective, observational pilot study.

BACKGROUND: A novel short-acting benzodiazepine, Remimazolam, has recently been approved for general anesthesia and sedation. Hence, we investigated the feasibility and safety of remimazolam during the induction and maintenance of general anesthesia without using a neuromuscular blocking agent (NMBA) in patients undergoing hysteroscopic surgery. METHODS: This prospective observational study included 38 patients undergoing hysteroscopic surgery. Remimazolam and remifentanil were the main anesthetic agents without an NMBA, and a supraglottic airway was inserted to protect the airway. The induction time, amount of each anesthetic agent used during anesthesia, intraoperative bispectral index (BIS) hemodynamic parameters, and recovery profiles were measured. RESULTS: General anesthesia was successfully administered to 37 patients using remimazolam and remifentanil without NMBA. The induction doses of remimazolam and remifentanil were 0.4 mg/kg (interquartile range [IQR] 0.34-0.47 mg/kg) and 1.07 µg/kg (IQR, 0.90-1.29 µg/kg), respectively. Additionally, the maintenance doses of remimazolam and remifentanil were 1.14 mg/kg/h (IQR, 0.88-1.55 mg/kg/h) and 0.06 µg/kg/min (IQR, 0.04-0.08 µg/kg/min), respectively. Intraoperative BIS values had risen temporarily > 60 in eight patients (21.6%) despite administration of 2 mg/kg/h of remimazolam; thus, they were treated with supplementary midazolam. The median recovery time was 7 min (IQR, 5-8 min) after 40 min (IQR, 40.0-57.5 min) of total mean anesthesia time. There was no correlation between the infusion dose of remimazolam and recovery profiles, such as recovery time, final BIS of anesthesia, modified observer assessment of alertness/sedation (OAA/S) scale or post-anesthesia recovery (PAR) score when arriving at the PACU, and length of stay in the PACU (all P > 0.05). CONCLUSION: Remimazolam can be combined with remifentanil without an NMBA in female patients who undergo hysteroscopic surgery, during which a supraglottic airway is a feasible method to protect the airway. TRIAL REGISTRATION: The study protocol was registered at ClinicalTrials.gov (NCT05025410) on 27/08/2021.

The voiding VAS score is a simple and useful method for predicting POUR after laparoscopy for benign gynaecologic diseases: a pilot study.

The aim of this study was to identify an appropriate scoring system for predicting postoperative urinary retention (POUR) after gynaecological laparoscopic surgery for benign disease. We analysed 99 patients who underwent gynaecological laparoscopic surgery for benign disease. All patients were asked to complete self-administered questionnaires, including the International Prostate Symptom Score (IPSS), voiding visual analogue scale (VAS), and Brief Pain Inventory-Korean version. Of the 99 patients, 27 (27.3%) experienced urinary retention at least once, while 72 (72.7%) did not. The preoperative and postoperative IPSS scores were not associated with the development of POUR. However, the voiding VAS score was significantly lower in patients that developed POUR (p = .014). In conclusion, our results show that the voiding VAS score is a simple and useful method for identifying patients at risk of POUR after gynaecologic laparoscopic surgery for benign disease. IMPACT STATEMENTWhat is already known on this subject? Postoperative urinary retention (POUR) is an often underestimated complication defined as inability to void during the postoperative period despite a full bladder. Undetected POUR may lead to complications such as urinary tract infection, bladder distention, and bladder dysfunction. Routine assessment of POUR by bladder ultrasonography in all surgical patients places a larger workload on the nursing staff.What do the results of this study add? Among the self-scoring assessment tools, the voiding VAS provided the most accurate reflection of POUR in patients undergoing gynaecologic laparoscopic surgery for benign disease.What are the implications of these findings for clinical practice and/or further research? As laparoscopy is the most widely employed surgical procedure in gynaecology, our findings could have significant implications for postoperative care in daily clinical practice.

Effects of ramosetron orally disintegrating tablets on the prophylaxis of post-discharge nausea and/or vomiting in female patients undergoing day surgery under general anesthesia: a randomized controlled trial.

BACKGROUND: This study was performed to evaluate the effectiveness of ramosetron orally disintegrating tablets (ODTs) in preventing post-discharge nausea and/or vomiting (PDNV) in female patients following outpatient surgery under general anesthesia. METHODS: This multicenter randomized study included three South Korean tertiary hospitals. Before surgery, 138 patients were randomly allocated into two groups. In the ramosetron group, ramosetron ODT 0.1 mg was administered after discharge in the morning of postoperative days 1 and 2. Metoclopramide 10 mg was administered as a rescue antiemetic (capped at 30 mg per day). In the control group, patients were administered only metoclopramide 10 mg when nausea and/or vomiting occurred. The primary outcome was the incidence of nausea during 24 h after discharge. RESULTS: We found significant differences in the incidence (13% vs. 33%, P = 0.008) and severity (P = 0.011) of nausea between the ramosetron and the control groups during 24 h after discharge. In addition, the rate of rescue antiemetic (metoclopramide) administration during 24 h after discharge was lower in the ramosetron group (6%) than in the control group (18%) (P = 0.033). Patient satisfaction score was higher in the ramosetron group than in the control group (P < 0.001). CONCLUSION: Ramosetron ODT reduces the incidence and severity of postoperative nausea after discharge during the first 24 h and may be a valuable option for the prevention of PDNV in female patients after day surgery under general anesthesia. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04297293 . Registered on 05 March 2020.

The Effects of Propofol or Dexmedetomidine Sedation on Postoperative Recovery in Elderly Patients Receiving Lower Limb Surgery under Spinal Anesthesia: A Retrospective Propensity Score-Matched Analysis.

Propofol and dexmedetomidine are the two most popular intravenous sedatives during anesthesia. However, data comparing the effects of these two sedatives during spinal anesthesia on postoperative recovery are still insufficient. We retrospectively analyzed the medical records of patients aged ≥65 years who underwent orthopedic surgery under spinal anesthesia between March 2012 and February 2017. The patients were allocated into two groups according to the intraoperative sedatives: the propofol group and dexmedetomidine group. We analyzed the incidence of postoperative delirium, analgesic requirement, and rescue anti-emetic treatment. A total of 1045 patients were included in the analysis. After propensity score matching with the propofol group, the dexmedetomidine group showed a lower incidence of postoperative delirium (odds ratio, 0.19; 95% CI, 0.07-0.56; p = 0.011). Postoperative analgesic and anti-emetic requirement were not significantly different between the two groups (p = 0.156 and 0.245, respectively). Multivariate logistic regression analysis revealed that intraoperative sedation, age, preoperative albumin level, and hip surgery were significantly associated with the incidence of postoperative delirium. This study showed that intraoperative dexmedetomidine sedation under spinal anesthesia during lower limb surgery is associated with a lower incidence of postoperative delirium compared with propofol sedation.

The Effect of Intraoperative Magnesium Sulphate Infusion on Emergence Agitation after Ambulatory Ophthalmic Surgery in Children.

This study investigated whether intraoperative infusion of magnesium sulphate reduces the incidence of emergence agitation (EA) in paediatric patients who undergo ambulatory ophthalmic surgery using the Paediatric Anaesthesia Emergence Delirium (PAED) scale. Ninety-two paediatric patients who were scheduled for elective ophthalmic surgery were randomly allocated to two groups: control or magnesium. In the magnesium group, patients received an initial intravenous loading dose of 30 mg/kg of 10% solution of magnesium sulphate over 10 min and then a continuous infusion of 10 mg/kg×h during the surgery. In the control group, an equal volume of 0.9% isotonic saline was administered in the same way as in the magnesium group. The PAED scale was assessed at 15-min intervals until the PAED score reached below 10 at the postanaesthetic care unit. EA was defined as a PAED score of 10 or higher. Of the 86 patients recruited, 44 and 42 were allocated to the control and magnesium groups, respectively. The incidence of EA was 77.3% in the control group and 57.1% in the magnesium group (odds ratio, 0.392; 95% confidence interval, 0.154 to 0.997; p = 0.046). The intraoperative infusion of magnesium sulphate significantly reduced the incidence of EA.

Dexmedetomidine-remifentanil vs propofol-remifentanil for monitored anesthesia care during hysteroscopy: Randomized, single-blind, controlled trial.

BACKGROUND: Although dexmedetomidine has been used as either the anesthetic agent for light sedation or as an adjunct to other sedatives, no study has investigated the usefulness of dexmedetomidine as the main sedative agent for invasive and painful procedures. The purpose of this study was to compare the safety of dexmedetomidine-remifentanil and propofol-remifentanil during monitored anesthesia care (MAC) for hysteroscopy. METHODS: Female patients undergoing hysteroscopy were randomly assigned to either the dexmedetomidine (group D) or the propofol group (group P). The study drug (0.6 ml/kg; dexmedetomidine 2 µg/ml or propofol 4 mg/ml) was loaded for 10 minutes followed by 0.1 to 0.5 ml/kg/hour to maintain a bispectral index of 60 to 80 during the procedure. In both groups, remifentanil was infused using a target-controlled-infusion system with a target concentration of 2 ng/ml and titrated during the procedure. The incidence rates of intraoperative respiratory depression in both groups were compared. Postoperative pain and patients satisfaction were also compared. RESULTS: A total of 69 female patients were included in this study. Dexmedetomidine significantly decrease the incidence of respiratory depression compared with propofol (15/34 [44.1%] vs 5/35 [14.3%], P = .006, group P and D, respectively). Postoperative pain and patients satisfaction score did not differ between the groups. CONCLUSION: The combination of dexmedetomidine-remifentanil can reduce the incidence of respiratory depression without increasing hemodynamic complications compared with propofol-remifentanil for MAC during hysteroscopy.

Magnesium and Pain.

In terms of antinociceptive action, the main mode of action of magnesium involves its antagonist action at the N-methyl-d-aspartate (NMDA) receptor, which prevents central sensitization and attenuates preexisting pain hypersensitivity. Given the pivotal function of NMDA receptors in pain transduction, magnesium has been investigated in a variety of pain conditions. The oral and parenteral administration of magnesium via the intravenous, intrathecal, or epidural route may alleviate pain and perioperative anesthetic and analgesic requirements. These beneficial effects of magnesium therapy have also been reported in patients with neuropathic pain, such as malignancy-related neurologic symptoms, diabetic neuropathy, postherpetic neuralgia, and chemotherapy-induced peripheral neuropathy. In addition, magnesium treatment is reportedly able to alleviate fibromyalgia, dysmenorrhea, headaches, and acute migraine attacks. Although magnesium plays an evolving role in pain management, better understanding of the mechanism underlying its antinociceptive action and additional clinical studies is required to clarify its role as an adjuvant analgesic.

Effects of Perioperative Magnesium Sulfate Administration on Postoperative Chronic Knee Pain in Patients Undergoing Total Knee Arthroplasty: A Retrospective Evaluation.

We aimed to investigate whether perioperative magnesium sulfate administration was associated with the incidence of chronic persistent postoperative pain (PPP) following total knee arthroplasty (TKA). This retrospective observational study was performed at a single tertiary academic hospital. We reviewed the medical records of adult patients who were admitted between August 2012 and July 2017. Patients who received magnesium sulfate during surgery were the magnesium group. The presence of PPP, one year after TKA, was evaluated using a binary logistic regression analysis. A total of 924 patients were included in the analysis, and 148 patients (16.0%) experienced PPP one year after TKA. In the multivariable model, the magnesium group had a 62% lower rate of PPP one year after TKA compared to the control group (odds ratio (OR): 0.38, 95% confidence interval (CI): 0.16 to 0.90; p = 0.027). This finding was similar in the sensitivity analysis using propensity score adjustment (OR: 0.38, 95% CI: 0.16 to 0.93; p = 0.036). We showed that perioperative magnesium sulfate administration was associated with a lower rate of PPP one year after TKA. Our results suggest that magnesium sulfate administered perioperatively is effective for the alleviation of acute and chronic pain after surgery.

Association of Preoperative Serum Chloride Levels With Mortality and Morbidity After Noncardiac Surgery: A Retrospective Cohort Study.

BACKGROUND: Postoperative hyperchloremia is known to be related to increases in mortality and morbidity after surgery. However, the relationship between preoperative hyperchloremia and hypochloremia and postoperative mortality and morbidity is not well established. Our aim was to evaluate the relationship between preoperative hyperchloremia or hypochloremia, as assessed using preoperative serum chloride tests, and 90-day mortality and morbidity after noncardiac surgery. METHODS: In this retrospective cohort study, we reviewed the medical records of patients >20 years of age who underwent noncardiac surgery between January 2010 and December 2016. Patients were categorized into one of the following groups on the basis of the results of serum chloride testing performed within 1 month before surgery: normochloremia, 97-110 mmol·L; hyperchloremia, >110 mmol·L; and hypochloremia, <97 mmol·L. The primary end point of this study was the difference in postoperative 90-day mortality among the preoperative serum chloride groups. The secondary end point was the difference in postoperative acute kidney injury incidence among the preoperative serum chloride groups. RESULTS: A total of 106,505 patients were included in the final analysis (2147 were allocated to the preoperative hypochloremia group and 617 to the hyperchloremia group). Multivariable Cox regression analysis revealed significantly increased 90-day mortality in the hypochloremia (hazard ratio, 1.46; 95% CI, 1.16-1.84; P = .001) and hyperchloremia (hazard ratio, 1.76; 95% CI, 1.13-2.73; P = .013) groups when compared with the normochloremia group. In addition, multivariable logistic regression analysis revealed a 1.83-fold increased odds of acute kidney injury in the preoperative hypochloremia group when compared with the normochloremia group (odds ratio, 1.83; 95% CI, 1.53-2.19; P < .001). CONCLUSIONS: Preoperative hypochloremia and hyperchloremia were related to increased 90-day mortality after noncardiac surgery. In addition, preoperative hypochloremia was related to an increased risk for postoperative acute kidney injury.

Comparison of Intraoperative Sedation With Dexmedetomidine Versus Propofol on Acute Postoperative Pain in Total Knee Arthroplasty Under Spinal Anesthesia: A Randomized Trial.

BACKGROUND: In patients undergoing total knee arthroplasty under spinal anesthesia, we compared the postoperative analgesic effect of intraoperative sedation with dexmedetomidine versus propofol. We hypothesized that sedation with dexmedetomidine would result in lower postoperative opioid analgesic consumption than with propofol. METHODS: Forty-eight patients were enrolled and randomly assigned to either a dexmedetomidine group (n = 24), which received a loading dose of 1 µg/kg dexmedetomidine over 10 minutes, followed by a continuous infusion of 0.1-0.5 µg·kg·hour, or a propofol group (n = 24), which received a continuous infusion of propofol via a target-controlled infusion to maintain the effect-site concentration within a range of 0.5-2.0 µg/mL. The drug infusion rate was determined according to the sedation level, targeting a modified observer's assessment of alertness/sedation score of 3 or 4. The cumulative amounts of fentanyl administered via intravenous patient-controlled analgesia were recorded at 24 and 48 hours postoperatively (primary outcome). The postoperative numerical rating scale for pain was assessed at 6, 12, 24, and 48 hours (secondary outcome). The postoperative use of additional rescue analgesic (ketoprofen) and antiemetic drugs was also compared between the 2 groups at 24 and 48 hours. RESULTS: Dexmedetomidine significantly reduced postoperative fentanyl consumption (median [interquartile range]) during 0-24 hours (45 [30-71] vs 150 [49-248] µg, P = .004; median difference = -105 µg [99.98% CI, 210-7.5]), 24-48 hours (90 [45-143] vs 188 [75-266] µg, P = .005; median difference = -98 µg [99.98% CI, 195-45]), and 0-48 hours (135 [68-195] vs 360 [146-480] µg, P = .003; median difference = -225 µg [99.98% CI, 405-7.5]). The numerical rating scale (median [interquartile range]) was lower at 6 hours (1 [0-2] vs 2 [1-3], P = .003), 12 hours (1 [1-2] vs 3 [2-3], P < .001), 24 hours (1 [1-2] vs 3 [2-3], P < .001), and 48 hours (2 [2-3] vs 3 [3-4], P < .001) after surgery in the dexmedetomidine group compared to the propofol group. No significant intergroup differences were observed in the amount of rescue analgesics and antiemetics at 24 hours (P = .155 and P = .482) and 48 hours (P = .082 and P = .153) after surgery. CONCLUSIONS: Intraoperative dexmedetomidine sedation was associated with a small but clinically important reduction in postoperative opioid use after total knee arthroplasty.