Seonghoon Ko

Postoperative delirium (POD) is a frequent and serious complication in older patients undergoing orthopedic surgery. This study aimed to compare the effects of midazolam and dexmedetomidine on the incidence of POD in elderly patients undergoing total knee arthroplasty under spinal anesthesia. In this prospective, double-blind, randomized, parallel group comparative trial, a total of 175 patients aged 65 years or older were allocated to receive either midazolam or dexmedetomidine for intraoperative sedation. The primary outcome was the incidence of POD, evaluated using the confusion assessment method for five postoperative days. Secondary outcomes included the quality of sedation, incidence of sedation failure, postoperative analgesic profiles, and complication rates. The incidence of POD was significantly lower in the dexmedetomidine group compared to the midazolam group (13.9% vs. 27.4%, P = 0.045). In addition, dexmedetomidine was associated with superior sedation quality and a significantly lower rate of sedation failure (P = 0.007 and P = 0.018, respectively). Postoperative pain intensity and complication rates were comparable between the two groups. Dexmedetomidine significantly reduced the incidence of POD and improved sedation quality compared to midazolam. These findings suggest that dexmedetomidine may be a preferable sedative for elderly patients undergoing total knee arthroplasty under spinal anesthesia. This study was registered with the WHO International Clinical Trials Registry Platform (Trial number: KCT0006587, Registration date: 16th September 2021).

Background: This study investigated the relationship between intraoperative requirement for an inhalational anesthetic (sevoflurane) or an opioid (remifentanil) and postoperative analgesic consumption. Methods: The study included 200 adult patients undergoing elective laparoscopic colectomy. In the sevoflurane group, the effect-site concentration of remifentanil was fixed at 1.0 ng/ml, while the inspiratory sevoflurane concentration was adjusted to maintain an appropriate anesthetic depth. In the remifentanil group, the end-expiratory sevoflurane concentration was fixed at 1.0 volume%, and the remifentanil concentration was adjusted. Pain scores and cumulative postoperative analgesic consumptions were evaluated at 2, 6, 24, and 48 h after surgery. Results: Average end-tidal concentration of sevoflurane and effect-site concentration of remifentanil were 2.0 ± 0.4 volume% and 3.9 ± 1.4 ng/ml in the sevoflurane and remifentanil groups, respectively. Cumulative postoperative analgesic consumption at 48 h postoperatively was 55 ± 26 ml in the sevoflurane group and 57 ± 33 ml in the remifentanil group. In the remifentanil group, the postoperative cumulative analgesic consumptions at 2 and 6 h were positively correlated with intraoperative remifentanil requirements (2 h: r = 0.36, P < 0.01; 6 h: r = 0.38, P < 0.01). However, there was no significant correlation in the sevoflurane group (r = 0.04, P = 0.69). Conclusions: The amount of intraoperative requirement of short acting opioid, remifentanil, is correlated with postoperative analgesic consumption within postoperative 6 h. It may be contributed by the development of acute opioid tolerance. However, intraoperative sevoflurane requirement had no effect on postoperative analgesic consumption.

(1) Background: This prospective observational study aimed to investigate the predictors affecting DMT requirements for sedation during regional anesthesia. (2) Method: A total of 108 patients who received regional anesthesia with intravenous DMT administration for orthopedic upper- or lower-extremity surgery were enrolled. Following successful regional anesthesia, DMT was administered at a rate of 4 µg/kg/h until reaching loss of consciousness (LOC). The administered dose of DMT per body weight until LOC (DMT_LOC; µg/kg) was evaluated. The infusion was maintained at a rate of 0.2–0.7 µg/kg/h during the surgery. At the end of surgery, the elapsed time to a BIS value of 90 (T_BIS90; s) was recorded. Linear regression models were used to identify potential predictors of DMT_LOC and T_BIS90. (3) Results: One hundred patients were analyzed. There were negative relationships between DMT_LOC and age (r = −0.297, p = 0.003) and DMT_LOC and body mass index (BMI) (r = −0.425, p < 0.001), respectively. Multiple linear regression models revealed that both increasing age and BMI were significantly related to DMT_LOC (r² = 0.259, p < 0.001), but those variables showed no association with T_BIS90. (4) Conclusions: The results of this study suggest that initial loading of DMT should be carefully titrated to minimize risk in elderly and obese surgical populations.

Background This study investigated the relationship between intraoperative requirement for an inhalational anesthetic (sevoflurane) or an opioid (remifentanil) and postoperative analgesic consumption. Methods The study included 200 adult patients undergoing elective laparoscopic colectomy. In the sevoflurane group, the effect-site concentration of remifentanil was fixed at 1.0 ng/ml, while the inspiratory sevoflurane concentration was adjusted to maintain an appropriate anesthetic depth. In the remifentanil group, the end-expiratory sevoflurane concentration was fixed at 1.0 volume%, and the remifentanil concentration was adjusted. Pain scores and cumulative postoperative analgesic consumptions were evaluated at 2, 6, 24, and 48 h after surgery. Results Average end-tidal concentration of sevoflurane and effect-site concentration of remifentanil were 2.0 ± 0.4 volume% and 3.9 ± 1.4 ng/ml in the sevoflurane and remifentanil groups, respectively. Cumulative postoperative analgesic consumption at 48 h postoperatively was 55 ± 26 ml in the sevoflurane group and 57 ± 33 ml in the remifentanil group. In the remifentanil group, the postoperative cumulative analgesic consumptions at 2 and 6 h were positively correlated with intraoperative remifentanil requirements (2 h: r = 0.36, P < 0.01; 6 h: r = 0.38, P < 0.01). However, there was no significant correlation in the sevoflurane group (r = 0.04, P = 0.69). Conclusion The amount of intraoperative requirement of short acting opioid, remifentanil, is correlated with postoperative analgesic consumption within postoperative 6 h. It may be contributed by the development of acute opioid tolerance. However, intraoperative sevoflurane requirement had no effect on postoperative analgesic consumption. Trial registration: KCT0004743

This prospective observational study evaluated the effects of body fat on the pharmacologic effect of propofol. Hundred patients aged 18 to 75 years who were scheduled to undergo orthopedic surgery under regional block were enrolled. All participants underwent bioelectrical impedance analysis and were allocated into 2 groups: the high and normal adiposity group, according to percent body fat. Following successful regional block, propofol was incrementally infused until loss of consciousness (LOC) with a target-controlled infusion pump. The effect-site concentration of propofol at LOC and the total infused dose of propofol per total body weight until LOC were recorded. At the end of the surgery, the infusion of propofol was stopped. The elapsed time to recovery of consciousness (ROC) and the effect-site concentration at ROC were recorded. These pharmacologic data were compared between 2 groups. The effect-site concentration of propofol at LOC (µg/mL) was significantly lower in the high adiposity group than in the normal group in both sexes (3.5 ± 0.4 vs 3.9 ± 0.6; P = .020 in males, and 3.4 [interquartile range: 2.9–3.5] vs 3.8 [interquartile range: 3.3–3.9]; P = .006 in females). Total dose per total body weight until LOC (mg/kg) were also significantly lower in the high adiposity group than in the normal group. There was no significant difference in the data related to ROC. The pharmacologic effects of propofol may be affected by the composition of body components. The concentration of propofol using a target-controlled infusion system may be diminished in patients with a high proportion of body fat.

BackgroundThis study aimed to evaluate the effects of hypercarbia on arterial oxygenation during one-lung ventilation (OLV).MethodsFifty adult patients undergoing elective video-assisted thoracoscopic lobectomy or pneumonectomy were enrolled. Group I patients (n = 25) were first maintained at normocarbia (PaCO2: 38‒42 mmHg) for 30 min and then at hypercarbia (45‒50 mmHg). In Group II patients (n = 25), PaCO2 was maintained in the reverse order. Arterial oxygen partial pressure (PaO2), respiratory variables, hemodynamic variables, and hemoglobin concentration were compared during normocarbia and hypercarbia. Arterial O2 content and O2 delivery were calculated.ResultsPaO2 values during normocarbia and hypercarbia were 66.5 ± 10.6 and 79.7 ± 17.3 mmHg, respectively (mean difference: 13.2 mmHg, 95% CI for difference of means: 17.0 to 9.3, P < 0.001). SaO2 values during normocarbia and hypercarbia were 92.5 ± 4.8% and 94.3 ± 3.1% (P = 0.009), respectively. Static compliance of the lung (33.0 ± 5.4 vs. 30.4 ± 5.3 ml/cmH2O, P < 0.001), arterial O2 content (15.4 ± 1.4 vs. 14.9 ± 1.5 ml/dl, P < 0.001) and O2 delivery (69.9 ± 18.4 vs. 65.1 ± 18.1 ml/min, P < 0.001) were significantly higher during hypercarbia than during normocarbia.ConclusionsHypercarbia increases PaO2 and O2 carrying capacity and improves pulmonary mechanics during OLV, suggesting that it may help manage oxygenation during OLV. Therefore, permissive hypercarbia may be a simple and valuable modality to manage arterial oxygenation during OLV.

Background: The present study was designed as a prospective, randomized, double‐blind clinical trial to evaluate the effects of preoperatively administered nefopam on postoperative acute hyperalgesia and the long‐term painful sequelae compared to intraoperative administration.Methods: One hundred and fifty patients undergoing elective laparoscopic colectomy were enrolled. Group 1 (post‐incisional nefopam) patients received saline at 30 min before skin incision followed by intraoperative administration of 20 mg nefopam at 1 h after incision. Group 2 (pre‐incisional nefopam) patients were administered 20 mg nefopam before skin incision and received saline after skin incision. At postoperative 2, 6, 24, 48, and 72 h, fentanyl consumption and pain intensities at rest and during deep breathing were evaluated by visual analog scale (VAS). The incidence of the long‐term painful sequelae after surgery was evaluated more than one year after surgery.Results: Cumulative fentanyl consumption during postoperative 72 h was similar between Group 1 and Group 2 (1534 ± 698 μg, 95% CI 1367–1702 μg vs. 1442 ± 721 μg, 95% CI 1266–1618 μg, P = 0.197). VAS pain scores at rest were comparable between the two groups, but VAS scores during deep breathing were significantly lower in Group 2 than in Group 1. Six and five patients complained of mild pain (pain rating 1) at the surgical site in Group 1 and 2, respectively.Conclusions: Preoperatively administered nefopam reduced exertional pain compared to intraoperative administration although postoperative analgesic consumption was similar between two groups. It may be helpful to conduct early ambulation and deep breathing during the acute postoperative period in patients undergoing intestinal surgery.Trial registration No: KCT0001656.

The purpose of this study was to determine whether intraoperative infusion of remifentanil induces acute tolerance to opioids, and compare the postoperative pain and opioid consumption by the effect site concentrations of remifentanil.

The current study evaluated the hemodynamic effects of different types of pneumatic compressions of the lower extremities during anesthesia induction. In addition, the hemodynamic effects were compared between patients older than 65 age years and those aged 65 years or younger. One hundred and eighty patients (90: > 65 years and 90: ≤ 65 years) were enrolled. Each age group of patients was randomly assigned to one of three groups; Group 1 (no compression), Group 2 (sequential pneumatic compression), and Group 3 (sustained pneumatic compression without decompression). Invasive blood pressure, cardiac index (CI), and stroke volume variation (SVV) were measured. In patients aged ≤ 65 years, mean arterial pressure (MAP) and CI were significantly higher and SVV was lower in Group 3 compared to Group 1 before tracheal intubation, but there were no differences between Groups 1 and 2. However, there were no differences in MAP, CI, and SVV among the three groups in patients aged > 65 years. The number of patients who showed a MAP < 60 mmHg was less in Group 3 than Group 1 in patients aged ≤ 65 years, but not in patients aged > 65 years. Sustained pneumatic compression of the lower extremities has more hemodynamic stabilizing effects compared to sequential compression during anesthesia induction in patients aged 65 years or younger. However, no difference between methods of compression was observed in patients older than 65 years.