Effect of Ketamine Added to Ropivacaine in Nerve Block for Postoperative Pain Management in Patients Undergoing Anterior Cruciate Ligament Reconstruction: A Randomized Trial.

PURPOSE: Nerve blocks are commonly used as a part of multimodal pain relief. It was previously shown that ketamine could enhance the analgesic effect of local anesthetics in nerve blocks. A literature review on adding ketamine to local anesthetics for ameliorating analgesia revealed inconsistencies in analgesic efficiency and safety. This prospective, randomized, double-blind trial was performed to evaluate the antinociceptive effect of mixing ketamine with local anesthetics in a combined femoral and sciatic nerve block (CFSNB) during anterior cruciate ligament (ACL) reconstruction. METHODS: Seventy-six patients undergoing preoperative ultrasound-guided CFSNB in ACL reconstruction were enrolled. Patients were randomly assigned to 3 groups: Group RNK received perineural administration of 40-mg ketamine plus 0.375% ropivacaine in 40-mL volume; Group RIK received 40 mL of 0.375% ropivacaine, as well as IV ketamine 40 mg; and Group R received 40 mL of 0.375% ropivacaine. Pain scores were recorded. AUC was calculated based on the pain scores at different times. Duration of CFSNB, postoperative analgesic demand, time to first analgesic demand, and adverse events were also examined. FINDINGS: Perineural ketamine decreased pain scores 20 and 24 h' postoperatively, as well as lowered AUC values (all, P = 0.001). Group RNK had a prolonged time to first analgesic request (P = 0.014), inhibited rebound pain (P = 0.001), and increased satisfactory score at 48 h' postsurgery (P = 0.001). Perineural ketamine prolonged the duration of sensory block (P = 0.001) with no effect on early mobilization. There were no significant differences between Group R and Group RIK in terms of postoperative pain scores, AUC of different time intervals (P = 0.832 or more), and time to first rescue analgesics (P = 0.585). Compared with the 2 other groups, IV ketamine had a higher incidence of hallucination after operations. IMPLICATIONS: Perineural ketamine added to the ropivacaine-enhanced analgesic efficacy of CFSNB with less rebound pain compared with the IV ketamine and control groups. IV ketamine had no effect in potentiating analgesia when a conventional multimodal approach was used in the study. Chinese Clinical Trial Registry: ChiCTR1900023867.

Warming efficacy of Ranger™ and FT2800 fluid warmer under different room temperatures and flow rates.

The comparison of the heating capabilities with different warming system between 3M™ Ranger™ warmer (3M) and FT2800 fluid warmer (FT) under different room temperatures and infusion rates, has been rarely reported previously. The study was then aimed to compare the warming efficacies of dry heat technology (3M) and coaxial warming system (FT) under different room temperatures and infusion rates, the advantages and disadvantages of both infusion systems would be compared to provide reference for clinical infusion practice. In the study, both target warming temperatures of 3M and FT warmer were set at 41 °C, fluid was administrated under 20, 22 and 24 °C room temperatures and drip rates of 60, 80, 100, 120, 140, 160, 200, 350 drops min-1. The fluid temperature at the outlet of the infusion tube (Toutlet) was measured and compared. The Toutlet of FT was higher than that of 3 M (P < 0.001) under different room temperatures. The Toutlet of FT increased with the room temperature raised (P < 0.05). As for 3M, Toutlet was lowest at 20 °C (P < 0.001) and no statistical difference of Toutlet was found between 22 and 24 °C (P = 0.667). Linear regression showed that the Toutlet of 3M increased with the speed up of drip rate, while the Toutlet of FT was decreased. The relationship between Toutlet & room temperature & drip rate for both 3M and FT warmers was calculated by a formula. 3M Ranger™ and FT2800 show different heating capabilities under different room temperatures and drip rates. 3M is more efficient at high flow rate while FT is more efficient at low flow rate. There is a formula relationship between Toutlet & room temperature & drip rate for both 3M and FT warmers.

The association of the optimal bolus of dexmedetomidine with its favourable haemodynamic outcomes in adult surgical patients under general anaesthesia.

AIMS: Dexmedetomidine is highly specific α2-adrenoceptor agonist. A single bolus of dexmedetomidine can achieve clinical therapeutic effect. Therefore, it is essential to know the safety margin between the clinical effectiveness dosages of dexmedetomidine and its side effect. METHODS: A total of 42 patients who underwent elective thyroidectomy were enrolled in this study. Dexmedetomidine was given as a single bolus injection 30 min towards the end of surgery. The up-and-down sequential schedule was used in this study. The starting dose of dexmedetomidine was set at 0.1 µg/kg in the first patient and the next patient would then receive a dose of dexmedetomidine decremented by 0.05 µg/kg if the prior patient's baseline heart rate (HR) had a decrease of ≥20% and/or mean arterial blood pressure (MAP) increase or decrease of ≥20%, otherwise, the following patient would receive an incremental 0.05 µg/kg dose of dexmedetomidine. The analytic techniques of linear, linear-logarithmic, exponential regressions and centred isotonic regression were used to determine the ED50 of dexmedetomidine and the residual standard errors were calculated for the comparison of goodness of fit among the different models. RESULTS: The median (interquartile range [range]) lowest HR was 57 beats/min (53-63.3[46-76]) with an average HR decrease of 8.0 beats/min (5-13 [4 to 23]). The median (interquartile range [range]) highest MAP was 98 mmHg (91.8-105 [83-126]) with a MAP increase of 10.0 mmHg (6.8-18.0 [2-24]). The ED50 (95% confidence interval) from 4 different statistical approaches (linear, linear-logarithmic, exponential regressions and centred isotonic regression) were 0.262 µg/kg (0.243, 0.306), 0.252 µg/kg (0.238, 0.307), 0.283 µg/kg (0.238, 0.307), and 0.278 µg/kg, respectively. Among the 4 models, the exponential regression had the least residual standard error (0.03618). CONCLUSION: The ED50 derived from 4 statistical models for an intravenous bolus of dexmedetomidine without significant haemodynamic effects was distributed in a narrow range of 0.252-0.283 µg/kg, and the exponential regression was the model to best match the study data.

Can noninvasive hemoglobin measurement reduce the need for preoperative venipuncture in pediatric outpatient surgery?

BACKGROUND: Noninvasive measurements of hemoglobin in the pediatric perioperative setting could be helpful to avoid venipunctures in children. The present study aims to evaluate this by using a noninvasive device for hemoglobin determination. We compared noninvasively obtained hemoglobin with laboratory hemoglobin concentrations in children during their preoperative assessment. METHODS: In an observational study, 122 nonanemic children (age 4.2 ± 1.6 years) who were scheduled to undergo different surgical procedures under general anesthesia were included. In their preoperative preparations, single invasive blood samples for laboratory hemoglobin concentrations were routinely taken following hospital policy and compared to simultaneous noninvasive determinations of hemoglobin. A preoperative invasive value ≤9 g/dL would have caused cancelation of surgery and implied further investigations. RESULTS: A Bland-Altman plot showed that the average difference between noninvasively obtained hemoglobin and laboratory hemoglobin concentration was -0.44 g/dL (bias) with a standard deviation of the mean bias of 1.04 g/dL. A hemoglobin error grid showed that the noninvasive device could identify almost all invasive hemoglobin values >9 g/dL. In total, there were 4 false-positive values where noninvasively obtained hemoglobin observations were below while the paired invasive values were above 9 g/dL. CONCLUSION: The data in this pediatric setting suggest that the device may eliminate the need for venipuncture in nonanemic children.