Regional Nerve Blocks Used in Renal Transplantation and Donor Nephrectomy: A Narrative Review

Perioperative opioid-related adverse drug events have been associated with increased length of hospitalization, higher costs, and increased patient mortality. Consequently, alternative means of analgesia, which may mitigate these risks, are important to explore. Peripheral nerve blocks (PNBs), including transversus abdominis block (TAPB), quadratus lumborum block (QLB), and erector spinae plane block (ESPB), have been used to reduce opioid requirements after renal transplant and donor nephrectomy. TAPB is most frequently studied; however, few studies compare approaches. PubMed was queried on July 13th 2022 and again on April 14th 2024 for studies on the use of regional analgesia for kidney transplantation and donor nephrectomy. This review surveys 29 publications that empirically investigated use of a PNB alone or as part of enhanced recovery after surgery (ERAS) protocols for patients undergoing renal transplant or donor nephrectomy, summarizing the evidence for each PNB. We found that TAPB was the most studied technique, and that few studies compared analgesic techniques. Overall, this body of research supports the use of TAPB to reduce pain and opioid requirements in the postoperative period after renal transplantation. Fewer studies support the use of TAPB following donor nephrectomy or the use of other PNBs for either procedure. Future studies may further investigate the use of TAPB after donor nephrectomy, compare various PNBs to TAPB, and investigate long-term outcomes.

The full spectrum of SLC22 OCT1 mutations illuminates the bridge between drug transporter biophysics and pharmacogenomics

Mutations in transporters can impact an individual's response to drugs and cause many diseases. Few variants in transporters have been evaluated for their functional impact. Here, we combine saturation mutagenesis and multi-phenotypic screening to dissect the impact of 11,213 missense single-amino-acid deletions, and synonymous variants across the 554 residues of OCT1, a key liver xenobiotic transporter. By quantifying in parallel expression and substrate uptake, we find that most variants exert their primary effect on protein abundance, a phenotype not commonly measured alongside function. Using our mutagenesis results combined with structure prediction and molecular dynamic simulations, we develop accurate structure-function models of the entire transport cycle, providing biophysical characterization of all known and possible human OCT1 polymorphisms. This work provides a complete functional map of OCT1 variants along with a framework for integrating functional genomics, biophysical modeling, and human genetics to predict variant effects on disease and drug efficacy.

The full spectrum of OCT1 (SLC22A1) mutations bridges transporter biophysics to drug pharmacogenomics

Membrane transporters play a fundamental role in the tissue distribution of endogenous compounds and xenobiotics and are major determinants of efficacy and side effects profiles. Polymorphisms within these drug transporters result in inter-individual variation in drug response, with some patients not responding to the recommended dosage of drug whereas others experience catastrophic side effects. For example, variants within the major hepatic Human organic cation transporter OCT1 (SLC22A1) can change endogenous organic cations and many prescription drug levels. To understand how variants mechanistically impact drug uptake, we systematically study how all known and possible single missense and single amino acid deletion variants impact expression and substrate uptake of OCT1. We find that human variants primarily disrupt function via folding rather than substrate uptake. Our study revealed that the major determinants of folding reside in the first 300 amino acids, including the first 6 transmembrane domains and the extracellular domain (ECD) with a stabilizing and highly conserved stabilizing helical motif making key interactions between the ECD and transmembrane domains. Using the functional data combined with computational approaches, we determine and validate a structure-function model of OCT1s conformational ensemble without experimental structures. Using this model and molecular dynamic simulations of key mutants, we determine biophysical mechanisms for how specific human variants alter transport phenotypes. We identify differences in frequencies of reduced function alleles across populations with East Asians vs European populations having the lowest and highest frequency of reduced function variants, respectively. Mining human population databases reveals that reduced function alleles of OCT1 identified in this study associate significantly with high LDL cholesterol levels. Our general approach broadly applied could transform the landscape of precision medicine by producing a mechanistic basis for understanding the effects of human mutations on disease and drug response.

Validation of Chinese version of a global anesthetic recovery questionnaire: A multicenter observational trial on ObsQoR-11

BACKGROUND

The obstetric quality of recovery (ObsQoR-11) is considered one of the best patient-reported outcome measures of post-cesarean recovery. However, it has been neither validated in Chinese nor evaluated at >24 h after delivery.

METHODS

Parturients from three hospitals (n = 279) completed the Chinese ObsQoR-11 at 24 h (T1) and 96 h (T2) after elective cesarean delivery. Convergent validity was assessed by correlation of Chinese ObsQoR-11 with a 100-mm numerical rating scale (NRS) of general health status; discriminant validity of good recovery (NRS ≥ 70-mm); and construct validity by correlation with influential factors to post-cesarean recovery. The reliability and responsiveness were also assessed.

RESULTS

The Chinese ObsQoR-11 correlated moderately with the NRS [T1: r = 0.38 (95% confidence interval: 0.28-0.48), p < 0.0001; T2: r = 0.43 (95% confidence interval: 0.32-0.52), p < 0.0001] and discriminated between good and poor recovery [T1: mean (SD) score: 64 (20) vs 49 (17), p < 0.0001; T2: median (IQR) score: 81 (66-94) vs. 61 (53-72); p = 0.0002]; weakly correlated with gestational age, successful breastfeeding, and operation time. It was reliable (internal consistency: 0.75 (T1) and 0.82 (T2); split-half: 0.77 (T1) and 0.85 (T2); test-retest intraclass correlation coefficient r > 0.6 for each item) and responsive (Cohen effect size: 0.88; standardized response mean: 0.81).

CONCLUSION

The Chinese ObsQoR-11may be used for assessing recovery at 24 h and 96 h after cesarean delivery. However, its' cutoff value for good recovery may be lower than that of other versions.

Dexamethasone and persistent wound pain: a prespecified analysis of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial

BACKGROUND

Dexamethasone is commonly administered intraoperatively to prevent postoperative nausea and vomiting and is believed to have analgesic properties. It is unknown whether it has an impact on chronic wound pain.

METHODS

In this prespecified embedded superiority substudy of the randomised PADDI trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and were followed up for 6 months postoperatively. The primary outcome was the incidence of pain in the surgical wound at 6 months. Secondary outcomes included acute postoperative pain and correlates of chronic postsurgical pain.

RESULTS

We included 8478 participants in the modified intention-to-treat population (4258 in the dexamethasone group and 4220 in the matched placebo group). The primary outcome occurred in 491 subjects (11.5%) in the dexamethasone arm and 404 (9.6%) subjects in the placebo arm (relative risk 1.2, 95% confidence interval 1.06-1.41, P=0.003). Maximum pain scores at rest and on movement in the first 3 postoperative days were lower in the dexamethasone group compared with the control group {median 5 (inter-quartile range [IQR] 3.0-8.0) vs 6 (IQR 3.0-8.0) and median 7 (IQR 5.0-9.0) vs 8 (IQR 6.0-9.0), P<0.001 for both}. Severity of postoperative pain was not predictive of chronic postsurgical pain. The severity of chronic postsurgical pain and the frequency of neuropathic features did not differ between treatment groups.

CONCLUSION

Administration of dexamethasone 8 mg i.v. was associated with an increase in the risk of pain in the surgical wound 6 months after surgery.

CLINICAL TRIAL REGISTRATION

ACTRN12614001226695.

Association Between Race and Opioid-Induced Respiratory Depression: An International Post Hoc Analysis of the Prediction of Opioid-induced Respiratory Depression In Patients Monitored by Capnography Trial

BACKGROUND

Opioid-induced respiratory depression (OIRD) is common on the medical and surgical wards and is associated with increased morbidity and health care costs. While previous studies have investigated risk factors for OIRD, the role of race remains unclear. We aim to investigate the association between race and OIRD occurrence on the medical/surgical ward.

METHODS

This is a post hoc analysis of the PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial; a prospective multinational observational blinded study of 1335 general ward patients who received parenteral opioids and underwent blinded capnography and oximetry monitoring to identify OIRD episodes. For this study, demographic and perioperative data, including race and comorbidities, were analyzed and assessed for potential associations with OIRD. Univariable χ 2 and Mann-Whitney U tests were used. Stepwise selection of all baseline and demographic characteristics was used in the multivariable logistic regression analysis.

RESULTS

A total of 1253 patients had sufficient racial data (317 Asian, 158 Black, 736 White, and 42 other races) for inclusion. The incidence of OIRD was 60% in Asians (N = 190/317), 25% in Blacks (N = 40/158), 43% in Whites (N = 316/736), and 45% (N = 19/42) in other races. Baseline characteristics varied significantly: Asians were older, more opioid naïve, and had higher opioid requirements, while Blacks had higher incidences of heart failure, obesity, and smoking. Stepwise multivariable logistic regression revealed that Asians had increased risk of OIRD compared to Blacks (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.54-4.04; P = .0002) and Whites (OR, 1.38; 95% CI, 1.01-1.87; P = .0432). Whites had a higher risk of OIRD compared to Blacks (OR, 1.81; 95% CI, 1.18-2.78; P = .0067). The model's area under the curve was 0.760 (95% CI, 0.733-0.787), with a Hosmer-Lemeshow goodness-of-fit test P value of .23.

CONCLUSIONS

This post hoc analysis of PRODIGY found a novel association between Asian race and increased OIRD incidence. Further study is required to elucidate its underlying mechanisms and develop targeted care pathways to reduce OIRD in susceptible populations.

Influence of Catheter-Incision Congruency in Epidural Analgesia on Postcesarean Pain Management: A Single-Blinded Randomized Controlled Trial

Patient-controlled epidural analgesia (PCEA) or epidural morphine may alleviate postcesarean pain; however, conventional lumbar epidural insertion is catheter–incision incongruent for cesarean delivery. Methods: In total, 189 women who underwent cesarean delivery were randomly divided into four groups (low thoracic PCEA, lumbar PCEA, low thoracic morphine, and lumbar morphine groups) for postcesarean pain management. Pain intensities, including static pain, dynamic pain, and uterine cramp, were measured using a 100 mm visual analog scale (VAS). The proportion of participants who experienced dynamic wound pain with a VAS score of >33 mm was evaluated as the primary outcome. Adverse effects, including lower extremity blockade, pruritus, postoperative nausea and vomiting, sedation, and time of first passage of flatulence, were evaluated. Results: The low thoracic PCEA group had the lowest proportion of participants reporting dynamic pain at 6 h after spinal anesthesia (low thoracic PCEA, 28.8%; lumbar PCEA, 69.4%; low thoracic morphine, 67.3%; lumbar morphine group, 73.9%; p < 0.001). The aforementioned group also reported the most favorable VAS scores for static, dynamic, and uterine cramp pain during the first 24 h after surgery. Adverse effect profiles were similar among the four groups, but a higher proportion of participants in the lumbar PCEA group (approximately 20% more than in the other three groups) reported prolonged postoperative lower extremity motor blockade (p = 0.005). In addition, the first passage of flatulence after surgery reported by the low thoracic PCEA group was approximately 8 h earlier than that of the two morphine groups (p < 0.001). Conclusions: Epidural congruency is essential to PCEA for postcesarean pain. Low thoracic PCEA achieves favorable analgesic effects and may promote postoperative gastrointestinal recovery without additional adverse effects.

The pharmacogenetics of opioid treatment for pain management

BACKGROUND

Opioids are widely used as an analgesic for the treatment of moderate to severe pain. However, there are interindividual variabilities in opioid response. Current evidence suggests that these variabilities can be attributed to single nucleotide polymorphisms in genes involved in opioid pharmacodynamics and pharmacokinetics. Knowledge of these genetic factors through pharamacogenetic (PGx) testing can help clinicians to more consistently prescribe opioids that can provide patients with maximal clinical benefit and minimal risk of adverse effects.

AIM

The research outlined in this literature review identifies variants involved in opioid PGx, which may be an important tool to achieving the goal of personalized pain management.

RESULTS

Cytochrome P450 (CYP) 2D6, CYP3A4, CYP3A5, catechol-o-methyltransferase (COMT), adenosine triphosphate binding cassette transporter B1 (ABCB1), opioid receptor mu 1 (OPRM1), and opioid receptor delta 1 (OPRD1) are all important genes involved in opioid drug response, side effect profile and risk of dependence; these are important genetic factors that should be included in potential opioid PGx tests for pain management.

CONCLUSIONS

Employing a PGx-guided strategy for prescribing opioids can improve response rate, reduce side effects and increase adherence to treatment plans for pain; more research is needed to explore opioid-related PGx factors for the development and validation of an opioid genetic panel. Optimal prescriptions could also provide healthcare payers with beneficial savings, while reducing the risk of propagating the current opioid crisis.

Racial Differences in Perioperative Opioid Utilization in Lumbar Decompression and Fusion Surgery for Symptomatic Lumbar Stenosis or Spondylolisthesis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To assess for racial differences in opioid utilization prior to and after lumbar fusion surgery for patients with lumbar stenosis or spondylolisthesis.

METHODS

Clinical records from patients with lumbar stenosis or spondylolisthesis undergoing primary <3-level lumbar fusion from 2007 to 2016 were gathered from a comprehensive insurance database. Records were queried by International Classification of Diseases diagnosis/procedure codes and insurance-specific generic drug codes. Opioid use 6 months prior, through 2 years after surgery was assessed. Multivariate regression analysis was employed to investigate independent predictors of opioid use following lumbar fusion.

RESULTS

A total of 13 257 patients underwent <3-level posterior lumbar fusion. The cohort racial distribution was as follows: 80.9% white, 7.0% black, 1.0% Hispanic, 0.2% Asian, 0.2% North American Native, 0.8% "Other," and 9.8% "Unknown." Overall, 57.8% patients utilized opioid medications prior to index surgery. When normalized by the number opiate users, all racial cohort saw a reduction in pills disbursed and dollars billed following surgery. Preoperatively, Hispanics had the largest average pills dispensed (222.8 pills/patient) and highest average amount billed ($74.67/patient) for opioid medications. The black cohort had the greatest proportion of patients utilizing preoperative opioids (61.8%), postoperative opioids (87.1%), and long-term opioid utilization (72.7%), defined as use >1 year after index operation. Multivariate logistic regression analysis indicated Asian patients (OR 0.422, 95% CI 0.191-0.991) were less likely to use opioids following lumbar fusion.

CONCLUSIONS

Racial differences exist in perioperative opioid utilization for patients undergoing lumbar fusion surgery for spinal stenosis or spondylolisthesis. Future studies are needed corroborate our findings.

Cross-Correlation Among Visual Analog, Observational, and Behavioral Pain Scales of Oncological Patients Undergoing Major Abdominal Surgery

PURPOSE

To determine the perception of postoperative pain intensity between nurses and oncology patients undergoing major abdominal surgery.

DESIGN

A prospective cross-correlation study with 173 oncology patients undergoing major abdominal surgery, such as hepatectomy or pancreatectomy.

METHODS

Postoperative pain intensity was evaluated by clinical pain assessment tools such as critical-care pain observation tool (CPOT) and behavioral pain scale (BPS) recorded by the researcher, whereas the visual analog scale was completed by patients. Demographic and clinical data were recorded.

FINDINGS

The Cronbach's α for CPOT and BPS was α = 0.738 for each. There was a significant correlation between CPOT and BPS (ρ = 0.796, P < .001), whereas the visual analog scale was correlated with CPOT and BPS (ρ = 0.351, P < .001 and ρ = 0.352, P < .001, respectively), showing that nurses did not underestimate patients' pain levels.

CONCLUSIONS

The management of postoperative pain intensity after major abdominal surgery requires clinical comprehension by nurses to achieve the reduction or suppression of pain.

Racial and Ethnic Disparities in Opioid Prescribing for Long Bone Fractures at Discharge From the Emergency Department: A Cross-sectional Analysis of 22 Centers From a Health Care Delivery System in Northern California

STUDY OBJECTIVE

We examine racial and ethnic differences in opioid prescribing and dosing for long bone fractures at emergency department (ED) discharge.

METHODS

We conducted an electronic health records-based cross-sectional study of adults with long bone fractures who presented to the ED across 22 sites from a health care delivery system (2016 to 2017). We examined differences in opioid prescribing at ED discharge and, among patients with a prescription, differences in opioid dosing (measured as morphine milligram equivalents) by race/ethnicity, using regression modeling with statistical adjustment for patient, fracture, and prescriber characteristics.

RESULTS

A total of 11,576 patients with long bone fractures were included in the study; 64.4% were non-Hispanic white; 16.4%, 7.3%, 5.8%, and 5.1%, respectively, were Hispanic, Asian, black, and of other or unknown race; and 65.6% received an opioid at discharge. After adjusting for other factors, rates of opioid prescribing were not different by race/ethnicity; however, among patients with an opioid prescription, total morphine milligram equivalent units prescribed were 4.3%, 6.0%, and 8.1% less for Hispanics, blacks, and Asians relative to non-Hispanic whites.

CONCLUSION

Racial and ethnic minority groups with long bone fractures receive similar frequencies of opioid prescriptions at discharge, with a small potency difference. How this affects pain relief and why it happens is unclear.

Laparoscopic Ventral Hernia Repair in South Auckland, New Zealand-A Retrospective Review

BACKGROUND

Ethnic disparities in surgical care and outcomes have been previously reported in studies for other surgical procedures. In addition, it has been reported that ethnic differences in postoperative analgesia exist. We aimed to determine ethnic disparities in postoperative outcomes, total opioid analgesia use, and complication rates of all patients who underwent a laparoscopic ventral hernia repair (LVHR) at our institution over a 3-y period.

METHODS

A retrospective review of all patients who underwent an LVHR at Counties Manukau Health from January 1, 2013, to December 31, 2015, was performed in line with the Strengthening the Reporting of Observational Studies in Epidemiology statement.

RESULTS

A total of 267 ventral hernias were repaired in 254 patients at Counties Manukau Health over the study period, of which most were primary umbilical ventral hernias. The majority of patients in our cohort were New Zealand European and male. Major complications, as per the Clavien-Dindo classification grade 3 and above, were observed in six patients with no deaths (2.4%). There were no statistically significant ethnic disparities in length of stay, receipt of opioid analgesia, and rates of complication observed after linear regression modeling after adjustment for confounding factors.

CONCLUSIONS

Our study showed that the majority of patients who had a ventral hernia repaired at our institution were mostly New Zealand European and male. Although significant ethnic disparities in patient characteristics were observed, these were not associated with ethnic disparities in postoperative outcomes after an LVHR.

Effect of cultural background and healthcare environment on postoperative opioid requirement

PURPOSE

The objective of this prospective observational study was to investigate the interactions between cultural background, healthcare environment, and postoperative pain experience.

METHODS

We enrolled 128 Chinese patients living in rural mainland China and 134 patients in Hong Kong with a higher level of Western cultural influences (defined by educational attainment, place of residence, and ability to understand English). All patients had major abdominal surgery and received patient-controlled analgesia with intravenous morphine for postoperative pain relief. The primary endpoint was total opioid requirement up to 48 hr after surgery. Other measures included pain intensity, opioid-related side effects, and genetic markers for opioid responsiveness.

RESULTS

The mean (95% confidence interval) cumulative opioid requirement, expressed as morphine equivalent, during the first 48 hr after surgery was significantly less in patients from mainland China (18.8 [15.7 to 22] mg) compared with patients from Hong Kong (42.0 [38.3 to 45.6] mg, P < 0.0001). In a multivariable analysis, opioid requirement was influenced by ethnicity, duration of surgery, and severity of pain upon admission to the postanesthetic care unit.

CONCLUSIONS

These results suggest that postoperative pain behaviours and opioid requirement may be influenced by cultural background and healthcare environment in two populations of Chinese descent.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ACTRN12614000601639); registered 6 May, 2014.

The pharmacogenetics of opioid therapy in the management of postpartum pain: a systematic review

AIMS

Opioids are commonly prescribed for postpartum pain. Yet, providing adequate pain relief, while ensuring that the mother and her breastfeeding infant are protected from adverse events can be challenging. The objective of this systematic review was to identify the role of opioid pharmacogenetics in analgesia and adverse events among patients being treated for postpartum pain, along with their breastfeeding infants.

METHODS

A comprehensive search of the literature was conducted in seven databases on June 3-4, 2015. Two reviewers independently screened studies for eligibility, extracted data and evaluated study quality using the Newcastle-Ottawa Scale.

RESULTS

Among the 2082 papers retrieved from the search, 17 were included in the review. These 17 papers consisted of various study designs, opioids, polymorphisms and patient outcomes. This systematic review reveals that CYP2D6, OPRM1 A118G, UGT2B7 C802T and ABCB1 G2677AT may contribute to postpartum analgesia or adverse events.

CONCLUSION

These findings may assist in personalizing care for patients receiving opioids during the postpartum period.

Acute postoperative pain relief with immediate-release tapentadol: randomized, double-blind, placebo-controlled study conducted in South Korea

OBJECTIVE

To broaden the ethnic groups in which tapentadol IR is evaluated for treating acute postoperative pain to include Asians.

METHODS

In this phase 3, multicenter, double-blind, randomized study, 352 Korean adults with moderate-to-severe pain following hallux valgus surgery received tapentadol IR 50 or 75 mg or placebo orally every 4-6 hours for 72 hours. Patients requesting other (rescue) analgesics during this period were discontinued for lack of efficacy. The primary endpoint, sum of pain intensity difference (SPID) over 48 hours, was evaluated based on the difference between tapentadol IR and placebo in least squares (LS) mean change from baseline using analysis of covariance (ANCOVA). Secondary endpoints included the time to first rescue medication use and the distribution of responder rates.

RESULTS

A treatment effect, favoring tapentadol IR, was observed for SPID48 (p < 0.001 for both doses vs. placebo, ANCOVA). The between-group difference (vs. placebo) in LS means of SPID48 was 76.4 (95% CI: 51.0, 101.7) for tapentadol IR 50 mg and 90.6 (95% CI: 65.1, 116.1) for tapentadol IR 75 mg. Time to first rescue medication use was delayed for tapentadol IR (p < 0.001 for both doses vs. placebo; log-rank test). The distribution of responders at 12, 24, 48, and 72 hours favored tapentadol IR (p ≤ 0.001 for both doses vs. placebo; Cochran-Mantel-Haenszel test). Dizziness, nausea, and vomiting were each reported in ≥ 10% tapentadol-treated patients and at an incidence ≥ 2-fold higher vs. placebo. The study findings may be limited by study drug dosing every 4 to 6 hours and frequent monitoring during treatment, neither of which mimic pain treatment in clinical practice. However, any potential bias based on this systematic monitoring of patients would be mitigated by the randomized, double-blind nature of the study, with all treatment groups similarly affected by such biases, if any.

CONCLUSIONS

Tapentadol IR reduced acute pain intensity, significantly more than placebo, after orthopedic surgery in Korean patients.

CLINICAL TRIAL REGISTRATION

NCT01516008.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

A comparison between dosages and plasma concentrations of dexmedetomidine in clinically ill patients: a prospective, observational, cohort study in Japan

Background

Dexmedetomidine is a highly selective central α₂-agonist with anesthetic and analgesic properties for patients in intensive care units. There is little information about the relationship between dosage and plasma concentration during long drug infusions of dexmedetomidine in critically ill patients, especially in Asians. In addition, the administration of dexmedetomidine with a dosage of 0.2–0.7 μg/kg/h in Japan is different from that with a dosage of 0.2–1.4 μg/kg/h in European countries and the USA. There has been concern about obtaining an effective concentration with a small dosage and estimating the relationship between dosage and plasma concentration. We conducted a prospective, observational, cohort study measuring plasma dexmedetomidine concentrations.

Methods

Plasma dexmedetomidine concentrations of 67 samples from 34 patients in an intensive care unit for 2 months were measured by ultra performance liquid chromatography coupled with tandem mass spectrometry using single-blind method, and the correlation coefficient between dosages and plasma concentrations was estimated. Exclusion criteria included young patients (<16 years) and samples obtained from patients in which the dosage of dexmedetomidine was changed within 3 h.

Results

Among the patients, 20 (58.8%) of the 34 received dexmedetomidine at 0.20–0.83 μg/kg/h, and in 40 of the 67 samples for which dexmedetomidine had been administered, this occurred for a median duration of 18.5 h (range, 3–87 h). The range of the dexmedetomidine plasma concentration was 0.22–2.50 ng/ml. By comparison with other studies, with a dosage of 0.2–0.7 μg/kg/h, the patients in this setting could obtain an effective dexmedetomidine concentration. The plasma dexmedetomidine concentration was moderately correlated with the administered dosage (r = 0.653, P < 0.01). The approximate linear equation was y = 0.171x + 0.254. The range of Richmond Agitation-Sedation Scale was 0 to -5.

Conclusions

We concluded that, with a dosage of 0.2–0.83 μg/kg/h, the patients in this setting could obtain an effective dexmedetomidine concentration of 0.22–2.50 ng/ml. In addition, the plasma dexmedetomidine concentration was moderately correlated with the administered dosage (r = 0.653, P < 0.01).

Trial registration

University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) UMIN000009115.