A Comparison of Efficacy between Low-dose Dexmedetomidine and Propofol for Prophylaxis of Postoperative Delirium in Elderly Patients Undergoing Hip Fracture Surgery: A Randomized Controlled Trial.

Aims and background: The efficacy of dexmedetomidine and propofol in preventing postoperative delirium is controversial. This study aims to evaluate the efficacy of dexmedetomidine and propofol for preventing postoperative delirium in extubated elderly patients undergoing hip fracture surgery. Materials and methods: This randomized controlled trial included participants undergoing hip fracture surgery. Participants were randomly assigned to receive dexmedetomidine, propofol, or placebo intravenously during intensive care unit (ICU) admission (8 p.m. to 6 a.m.). The drug dosages were adjusted to achieve the Richmond Agitation Sedation Scale (RASS) of 0 to -1. The primary outcome was postoperative delirium. The secondary outcomes were postoperative complications, fentanyl consumption, and length of hospital stay. Results: 108 participants were enrolled (n = 36 per group). Postoperative delirium incidences were 8.3%, 22.2%, and 5.6% in the dexmedetomidine, propofol, and placebo groups, respectively. The hazard ratios of dexmedetomidine and propofol compared with placebo were 1.49 (95% CI, 0.25, 8.95; p = 0.66) and 4.18 (95% CI, 0.88, 19.69; p = 0.07). The incidence of bradycardia was higher in the dexmedetomidine group compared with others (13.9%; p = 0.01) but not for hypotension (8.3%; p = 0.32). The median length of hospital stays (8 days, IQR: 7, 11) and fentanyl consumption (240 µg, IQR: 120, 400) were not different among groups. Conclusion: This study did not successfully demonstrate the impact of nocturnal low-dose dexmedetomidine and propofol in preventing postoperative delirium among elderly patients undergoing hip fracture surgery. While not statistically significant, it is noteworthy that propofol exhibited a comparatively higher delirium rate. How to cite this article: Ekkapat G, Kampitak W, Theerasuwipakorn N, Kittipongpattana J, Engsusophon P, Phannajit J, et al. A Comparison of Efficacy between Low-dose Dexmedetomidine and Propofol for Prophylaxis of Postoperative Delirium in Elderly Patients Undergoing Hip Fracture Surgery: A Randomized Controlled Trial. Indian J Crit Care Med 2024;28(5):467-474.

A randomized comparison between intravenous and perineural dexamethasone for ultrasound-guided axillary block.

BACKGROUND: This randomized double-blinded trial compared the effect of intravenous and perineural dexamethasone (8 mg) on the duration of motor block for ultrasound (US)-guided axillary brachial plexus block (AXB). METHODS: Patients undergoing upper limb surgery with US-guided AXB were randomly allocated to receive preservative-free dexamethasone (8 mg) via intravenous (n = 75) or perineural (n = 75) administration. The local anesthetic agent, 1% lidocaine -0.25% bupivacaine (30 mL) with epinephrine 5 µg·mL-1, was identical in all subjects. Operators and patients were blinded to the nature of the intravenous and perineural injectate. A blinded observer assessed the block success rate (i.e., a minimal sensorimotor composite score of 14 out of 16 points at 30 min), block onset time, as well as the presence of surgical anesthesia. Postoperatively, the blinded observer contacted all patients with successful blocks to record the duration of motor block (primary outcome), sensory block, and postoperative analgesia. RESULTS: No intergroup differences were observed in terms of success rate, surgical anesthesia, and block onset time. Compared to intravenous administration, perineural dexamethasone provided longer mean (SD) durations for motor block [17.5 (4.6) hr vs 12.8 (4.5) hr; mean difference, 4.6 hr; 95% confidence interval [CI], -6.21 to -3.08; P < 0.001], sensory block [17.7 (5.1) hr vs 13.7 (5.0) hr; mean difference, 4.0 hr; 95% CI, -5.77 to -2.27; P < 0.001], and postoperative analgesia [21.1 (4.6) hr vs 17.1 (4.6) hr; mean difference, 4.0 hr; 95% CI, -5.70 to -2.30; P < 0.001]. CONCLUSION: Compared to intravenous dosing, perineural dexamethasone (8 mg) results in longer durations of sensorimotor block and postoperative analgesia for ultrasound-guided axillary block. This trial was registered at www.clinicaltrials.gov number, NCT02629835.

Noradrenaline, Serotonin, GABA, and Glycine in Cerebrospinal Fluid during Labor Pain: A Cross-Sectional Prospective Study.

BACKGROUND AND AIMS: The inhibitory pathways that play a role in spinal modulation include local interneurons and descending control. Clinical data regarding the role of these pathways in acute pain is lacking. Accordingly, the aim of this study was to evaluate cerebrospinal fluid (CSF) levels of noradrenaline, serotonin, gamma-aminobutyric acid (GABA), and glycine in parturients with labor pain compared to those without labor pain. METHODS: One hundred term uncomplicated pregnant women receiving spinal anesthesia for cesarean section were enrolled in this prospective cross-sectional study. CSF noradrenaline, serotonin, GABA, and glycine levels were analyzed by enzyme-linked immunosorbent assay. Labor pain score was assessed by numerical rating scale. RESULTS: Median CSF serotonin concentration in parturients with labor pain was significantly lower than in those without pain (p < 0.001). Median CSF glycine level in the labor pain group was significantly higher than in the control group (p < 0.001). There were no significant differences in median CSF level of noradrenaline or GABA between parturients with and without labor pain. Subsequent analysis showed labor pain scores to be negatively correlated with CSF serotonin (r = -0.217, p = 0.04) but positively correlated with CSF glycine (r = 0.415, p < 0.001). CONCLUSION: CSF serotonin and glycine were significantly correlated with labor pain scores. These findings suggest that the serotonergic and glycinergic systems may play a role in spinal modulation of visceral pain.

Primary Failure of Thoracic Epidural Analgesia in Training Centers: The Invisible Elephant?

In teaching centers, primary failure of thoracic epidural analgesia can be due to multiple etiologies. In addition to the difficult anatomy of the thoracic spine, the conventional end point-loss-of-resistance-lacks specificity. Furthermore, insufficient training compounds the problem: learning curves are nonexistent, pedagogical requirements are often inadequate, supervisors may be inexperienced, and exposure during residency is decreasing. Any viable solution needs to be multifaceted. Learning curves should be explored to determine the minimal number of blocks required for proficiency. The problem of decreasing caseload can be tackled with epidural simulators to supplement in vivo learning. From a technical standpoint, fluoroscopy and ultrasonography could be used to navigate the complex anatomy of the thoracic spine. Finally, correct identification of the thoracic epidural space should be confirmed with objective, real-time modalities such as neurostimulation and waveform analysis.

A Randomized Comparison Between Conventional and Waveform-Confirmed Loss of Resistance for Thoracic Epidural Blocks.

BACKGROUND AND OBJECTIVES: Epidural waveform analysis (EWA) provides a simple confirmatory adjunct for loss of resistance (LOR): when the needle tip is correctly positioned inside the epidural space, pressure measurement results in a pulsatile waveform. In this randomized trial, we compared conventional and EWA-confirmed LOR in 2 teaching centers. Our research hypothesis was that EWA-confirmed LOR would decrease the failure rate of thoracic epidural blocks. METHODS: One hundred patients undergoing thoracic epidural blocks for thoracic surgery, abdominal surgery, or rib fractures were randomized to conventional LOR or EWA-LOR. The operator was allowed as many attempts as necessary to achieve a satisfactory LOR (by feel) in the conventional group. In the EWA-LOR group, LOR was confirmed by connecting the epidural needle to a pressure transducer using a rigid extension tubing. Positive waveforms indicated that the needle tip was positioned inside the epidural space. The operator was allowed a maximum of 3 different intervertebral levels to obtain a positive waveform. If waveforms were still absent at the third level, the operator simply accepted LOR as the technical end point. However, the patient was retained in the EWA-LOR group (intent-to-treat analysis).After achieving a satisfactory tactile LOR (conventional group), positive waveforms (EWA-LOR group), or a third intervertebral level with LOR but no waveform (EWA-LOR group), the operator administered a 4-mL test dose of lidocaine 2% with epinephrine 5 µg/mL. Fifteen minutes after the test dose, a blinded investigator assessed the patient for sensory block to ice. RESULTS: Compared with LOR, EWA-LOR resulted in a lower rate of primary failure (2% vs 24%; P = 0.002). Subgroup analysis based on experience level reveals that EWA-LOR outperformed conventional LOR for novice (P = 0.001) but not expert operators. The performance time was longer in the EWA-LOR group (11.2 ± 6.2 vs 8.0 ± 4.6 minutes; P = 0.006). Both groups were comparable in terms of operator's level of expertise, depth of the epidural space, approach, and LOR medium. In the EWA-LOR group, operators obtained a pulsatile waveform with the first level attempted in 60% of patients. However, 40% of subjects required performance at a second or third level. CONCLUSIONS: Compared with its conventional counterpart, EWA-confirmed LOR results in a lower failure rate for thoracic epidural blocks (2% vs 24%) in our teaching centers. Confirmatory EWA provides significant benefits for inexperienced operators.

A Multicenter Randomized Comparison Between Intravenous and Perineural Dexamethasone for Ultrasound-Guided Infraclavicular Block.

BACKGROUND AND OBJECTIVES: This multicenter, randomized trial compared intravenous (IV) and perineural (PN) dexamethasone for ultrasound (US)-guided infraclavicular brachial plexus block. Our research hypothesis was both modalities would result in similar durations of motor block. METHODS: One hundred fifty patients undergoing upper limb surgery with US-guided infraclavicular block were randomly allocated to receive IV or PN dexamethasone (5 mg). The local anesthetic agent (35 mL of lidocaine 1%-bupivacaine 0.25% with epinephrine 5 µg/mL) was identical in all subjects. Patients and operators were blinded to the nature of IV and PN injectates. During the performance of the block, the performance time, number of needle passes, procedural pain, and complications (vascular puncture, paresthesia) were recorded.Subsequently, a blinded observer assessed the success rate (defined as a minimal sensorimotor composite score of 14 of 16 points at 30 minutes), onset time as well as the incidence of surgical anesthesia (defined as the ability to complete surgery without local infiltration, supplemental blocks, IV opioids, or general anesthesia). Postoperatively (at 24 hours), the blinded observer contacted patients with successful blocks to enquire about the duration of motor block, sensory block, and postoperative analgesia. The main outcome variable was the duration of motor block. RESULTS: No intergroup differences were observed in terms of technical execution (performance time/number of needle passes/procedural pain/complications), onset time, success rate, and surgical anesthesia. However, compared to its IV counterpart, PN dexamethasone provided 19% to 22% longer durations for motor block (15.7 ± 6.2 vs 12.9 ± 5.5 hours; P = 0.009), sensory block (16.8 ± 4.4 vs 13.9 ± 5.4 hours; P = 0.002), and postoperative analgesia (22.1 ± 8.5 vs 18.6 ± 6.7 hours; P = 0.014). CONCLUSIONS: Compared with its IV counterpart, PN dexamethasone (5 mg) provides a longer duration of motor block, sensory block, and postoperative analgesia for US-guided infraclavicular block. Future dose-finding studies are required to elucidate the optimal dose of dexamethasone.