Determining the Optimal Dosage of Dexmedetomidine for Smooth Emergence in Older Patients Undergoing Spinal Surgery: A Study of 44 Cases.

BACKGROUND Emergence agitation, or delirium, occurs during early recovery from general anesthesia and involves disorientation, excitation, and uncontrolled physical movements. Dexmedetomidine is an alpha agonist that has sedative, anxiolytic, analgesic, and sympatholytic activities and is used as a continuous infusion to prevent emergence agitation. This study aimed to evaluate patients aged 65 years and older undergoing general anesthesia to determine the 90% effective dose (ED90) of dexmedetomidine continuous intraoperative infusion to prevent emergence agitation. MATERIAL AND METHODS We enrolled 44 patients aged 65 years and older undergoing spinal surgery under general anesthesia. Dexmedetomidine administration commenced 30 minutes before surgery completion, with a predetermined infusion dose (µg/kg/h), without a loading dose. The initial dose was 0.2 µg/kg/h, and subsequent step size was ±0.05 µg/kg/h. We tried to find ED90 of dexmedetomidine using the biased-coin design. Vital signs, extubation quality scores, extubation-related complications, and postoperative outcomes were monitored. RESULTS Dexmedetomidine ED90 for smooth emergence in older patients was 0.34 µg/kg/h. Peri-extubation vital signs remained within 20% of baseline values, without requiring pharmacological intervention. No hypoxia, hypoventilation, or post-extubation agitation occurred. In the recovery room, 1 patient briefly exhibited excitement but quickly calmed. Nine patients initially unresponsive in the recovery room fully awoke and were promptly discharged. CONCLUSIONS For older patients who are vulnerable to adverse effects of anesthetics and opioids, dexmedetomidine enables gentle awakening without adverse vital sign changes, respiratory depression, excessive sedation, or emergence agitation (ED90=0.34 µg/kg/h). Further studies should involve a larger patient cohort, considering diverse medical conditions in older individuals.

Comparison of the effects of dexmedetomidine and propofol on the cardiovascular autonomic nervous system during spinal anesthesia: preliminary randomized controlled observational study.

Spinal anesthesia induces sympatholysis and is usually combined with dexmedetomidine or propofol which induce different hemodynamic changes. The purpose of this study was to compare the effect on autonomic nervous system between dexmedetomidine and propofol combined with spinal anesthesia. Patients aged 20-65 undergoing elective surgery under spinal anesthesia were randomly assigned to dexmedetomidine or propofol group. Heart rate variability (HRV) and hemodynamic variables were measured at four time points: T0, baseline; T1, 10 min after spinal anesthesia; T2, 10 min after sedative administration; and T3, 20 min after sedative administration. In 59 patients, dexmedetomidine and propofol groups had significantly different hemodynamic changes over time (time × group effect P < 0.001). The dexmedetomidine group had slower heart rate at T2 (P = 0.001) and higher blood pressures at T2 and T3 (P < 0.001) than the propofol group. Overall HRV dynamics showed a significant change over time from T0 to T3, but both groups exhibited similar trends. Compared to the baseline data within the group, the low frequency (LF) decreased in both groups but the decrease occurred at T2 in the propofol group and at T3 in the dexmedetomidine group. The high frequency (HF) increased at T2 and T3 only in the dexmedetomidine group. The LF/HF ratio decreased in the dexmedetomidine group at T3. Dexmedetomidine showed slower heart rate and higher blood pressure than propofol when combined with spinal anesthesia, however, dexmedetomidine and propofol exhibited similar trends in HRV dynamics. Compared with the baseline within each group, both agents decreased LF, but only dexmedetomidine increased HF and decreased in the LF/HF ratio significantly.

Late Mortality Prediction of Neutrophil-to-Lymphocyte and Platelet Ratio in Patients With Trauma Who Underwent Emergency Surgery: A Retrospective Study.

BACKGROUND: We aimed to evaluate the usefulness of neutrophil-to-lymphocyte (N/L) and neutrophil-to-lymphocyte platelet (N/LP) ratios in predicting late mortality of patients with trauma who underwent emergency surgery. MATERIALS AND METHODS: We retrospectively evaluated patients with trauma older than 19 y who underwent emergency surgery at our level I trauma center. Blood count-based ratios (N/L and N/LP at days 1, 3, and 7 of hospitalization) and trauma scores were analyzed. Statistical analysis was performed using univariable logistic regression and receiver operating curves. RESULTS: A total of 209 patients were evaluated. N/LP at day 7, N/L at day 7, Trauma Injury Severity Score, Revised Trauma Score, and Injury Severity Score were significantly associated with late mortality. Area under the receiver operating characteristic curves for predicting mortality was highest for N/LP at day 7 (0.867 [95% confidence interval 0.798-0.936], P < 0.001). The group with N/LP greater than the cutoff value (9.3, sensitivity 77.3%, specificity 83.1%) at day 7 showed higher mortality than the group with N/LP less than the cutoff value (35.4% versus 3.2%, P < 0.001, respectively) at day 7. CONCLUSIONS: N/LP at day 7 may be a superior predictor of late mortality compared with preexisting trauma scores in patients with major trauma undergoing emergency surgery, by better reflecting the systemic inflammation status.

Lightwand-Guided Insertion of Flexible Reinforced Laryngeal Mask Airway: Comparison with Standard Digital Manipulation Insertion.

BACKGROUND The flexibility of the long flexometallic tube makes insertion of the flexible reinforced laryngeal mask airway (f-LMA) difficult. We compared the usefulness of rigid lightwand-guided f-LMA insertion with standard digital manipulation. MATERIAL AND METHODS Fifty-four patients (aged 19-70 years) were randomly divided into a control group (digital manipulation technique) or the lightwand group (lightwand-guided insertion technique). The insertion profiles, oropharyngeal leak pressure (OLP), peak inspiratory pressure (PIP), expiratory tidal volume, and ventilatory score were measured in patients with neutral, extension, rotation, flexion, and re-neutral head-neck positions in turn. RESULTS The success rate and ease of insertion did not differ between groups, but the insertion time was longer in the lightwand group. The fiberoptic laryngeal view was significantly better in the lightwand group than in the control group. However, the OLP, PIP, expiratory tidal volume, and ventilatory scores were not significantly different between groups according to head-neck positions. The extension posture was associated with a significant negative effect on ventilation, but ventilation returned to initial levels with the other postures. CONCLUSIONS Lightwand-guided f-LMA insertion showed a better fiberoptic laryngeal view than standard digital manipulation, but no improvement in the ventilatory state was observed due to position. Therefore, lightwand-guided insertion could facilitate correct placement of the f-LMA, but it has limited clinical usefulness.

Conversion of I-gel to definitive airway in a cervical immobilized manikin: Aintree intubation catheter vs long endotracheal tube.

BACKGROUND: After prehospital insertion of i-gel, a popular supraglottic airway (SGA), fiberoptic-guided intubation through i-gel is often required to switch the i-gel to a definitive airway for anticipated difficult airway. The Aintree intubation catheter (AIC) was developed for this purpose yet it requires many procedural steps during which maintenance of adequate ventilation is difficult. We custom-made a long endotracheal tube (LET) which may facilitate this procedure and compared the efficacy of the AIC and LET in a cervical immobilized manikin. METHODS: In this 2 × 2 crossover manikin-based trial, 20 anaesthesiologists and residents performed both methods in random order. Total intubation time, fiberoptic time, and procedure time were recorded. The ease of insertion, procedure failure rate, difficulty score, and participants' preference were recorded. RESULTS: Total intubation time was significantly shorter for the LET than the AIC group (70.8 ± 16.4 s vs 94.0 ± 28.4 s, P = 0.001). The procedure time was significantly shorter in the LET group (51.9 ± 13.8 s vs 76.5 ± 25.4 s, P <  0.001). The ease of insertion score was lower, i.e., easier, in the AIC than the LET group (2.0 [1.0-2.75] vs 1.0 [1.0-1.0], P <  0.001). Fiberoptic time (19.0 ± 6.9 s vs 17.5 ± 12.3 s) and subjective difficulty (4.0 [3.0-6.0] vs 4.0 [3.0-5.75]) were similar between groups. Fourteen participants preferred the LET method (70%) due to its fewer procedural steps. CONCLUSIONS: LET resulted in a shorter intubation time than the AIC during fiberoptic-guided intubation through the i-gel, possibly due to the less procedural steps compared to AIC. TRIAL REGISTRATION: NCT03645174 (ClinicalTrials.gov, Aug 22, 2018).

Trigeminal nerve block with alcohol for medically intractable classic trigeminal neuralgia: long-term clinical effectiveness on pain.

BACKGROUND: Trigeminal nerve block (Tnb) with alcohol for trigeminal neuralgia (TN) may not be used widely as a percutaneous procedure for medically intractable TN in recent clinical work, because it has been considered having a limited duration of pain relief, a decrease in success rate and increase in complications on repeated blocks. OBJECTIVES: To evaluate the clinical outcome of the Tnb with alcohol in the treatment of medically intractable TN. METHODS: Six hundred thirty-two patients were diagnosed with TN between March 2000 and February 2010. Four hundred sixty-five out of 632 underwent Tnb with alcohol under a fluoroscope. Pain relief duration were analyzed and compared in the individual branch blocks. Outcomes were compared between patients with and without a previous Tnb with alcohol. RESULTS: Tnb with alcohol were performed in a total 710 (1st-465, 2nd-155, 3rd-55, 4th-23, 5th-8, 6th-4) cases for a series of consecutive 465 patients during the study period. Forty hundred sixty two out of the 465 patients experienced immediate complete pain relief (99%) at the first Tnb. Of the 465 patients, 218 patients (46.9%) did not require any further treatment after the first Tnb with alcohol during an entire study period. One hundred fifty nine (34.2 %) out of the 465 patients experienced recurring pain after the first block, among whom 155 patients received subsequent blocks, and the remaining 4 patients decided to take medication. According to the Kaplan-Meier analysis, the probabilities of remaining pain relief for 1, 2, 3, and 5 years after the procedures were 86.2%, 65.5%, 52.5%, and 33.4%, respectively. There was no significant difference in the probability of pain relief duration between patients with and without previous Tnb with alcohol. Median (95% CI) pain relief durations of the first and repeated blocks were 39 (36-51) and 37 (28-54) months, respectively. There was no significant difference in occurrence of complications between patients with and without previous Tnb with alcohol (p <0.076). All the complications recovered spontaneously within 6 months. There was no mortality related to the procedure. CONCLUSIONS: Tnb with alcohol for the pain management of TN can provide considerably long lasting pain relief. Repeated Tnb with alcohol has pain relief duration as long as the first block, and seems to produce less complication as well. Tnb with alcohol is a valuable treatment modality of TN as a percutaneous procedure.

Disconnection technique with a bronchial blocker for improving lung deflation: a comparison with a double-lumen tube and bronchial blocker without disconnection.

OBJECTIVE: One-lung ventilation (OLV) is accomplished with a double-lumen tube (DLT) or a bronchial blocker (BB). The authors compared the effectiveness of lung collapse using DLT, BB, and BB with the disconnection technique. DESIGN: Prospective, randomized, blind trial. SETTING: A university hospital. PARTICIPANTS: Fifty-two patients undergoing elective pneumothorax surgery. INTERVENTIONS: Patients were assigned randomly to 1 of 3 groups: The DLT group (group 1), the BB group (group 2), and the BB with the disconnection technique group (group 3). The authors modified the disconnection technique in group 3 as follows: (1) turned off the ventilator and opened the adjustable pressure-limiting valve, allowing both lungs to collapse and (2) after loss of the CO2 trace on the capnograph, inflated the blocker cuff and turned on the ventilator, allowing only dependent-lung ventilation. MEASUREMENTS AND MAIN RESULTS: Five and ten minutes after OLV, the degree of lung collapse was assessed by the surgeon, who was blinded to the isolation technique. The quality of lung collapse at 5 and 10 minutes was significantly better in groups 1 and 3 than in group 2. No significant differences were observed for the degree of lung collapse at any time point between groups 1 and 3. The average time for loss of the CO2 trace on the capnograph was 32.3±7.0 seconds in group 3. CONCLUSIONS: A BB with spontaneous collapse took longer to deflate and did not provide equivalent surgical exposure to the DLT. The disconnection technique could be helpful to accelerate lung collapse with a BB.

Pharmacological and nonpharmacological prevention of fentanyl-induced cough: a meta-analysis.

Fentanyl-induced cough (FIC) is often observed after intravenous bolus administration of fentanyl during anesthesia induction. This meta-analysis assessed the efficacy of pharmacological and nonpharmacological interventions to reduce the incidence of FIC. We searched for randomized controlled trials comparing pharmacological or nonpharmacological interventions with controls to prevent FIC; we included 28 studies retrieved from Pub-Med, Embase, and Cochrane Library. Overall incidence of FIC was approximately 31 %. Lidocaine [odds ratio (OR) = 0.29, 95 % confidence interval (CI) 0.21­0.39], N-methyl-D-aspartate (NMDA) receptor antagonists (OR 0.09, 95 % CI 0.02­0.42), propofol (OR 0.07, 95 % CI 0.01­0.36), a2 agonists (OR 0.32, 95 % CI 0.21­0.48), b2 agonists (OR 0.10, 95 % CI 0.03­0.30), fentanyl priming (OR 0.33, 95 % CI 0.19­0.56), and slow injection of fentanyl (OR 0.25, 95 % CI 0.11­0.58)] were effective in decreasing the incidence of FIC, whereas atropine (OR 1.10, 95 % CI 0.58­2.11) and benzodiazepines (OR 2.04, 95 % CI 1.33­3.13) were not effective. This meta-analysis found that lidocaine, NMDA receptor antagonists, propofol, a2 agonists, b2 agonists, and priming dose of fentanyl were effective in preventing FIC, but atropine and benzodiazepines were not. Slow injection of fentanyl was effective in preventing FIC, but results depend on the speed of administration.

Comparison of the incidence of postoperative nausea and vomiting between women undergoing open or robot-assisted thyroidectomy.

BACKGROUND: Open thyroidectomy is associated with a high incidence of postoperative nausea and vomiting (PONV) in up to 70 % of cases. Use of the recently introduced robot-assisted endoscopic thyroidectomy using a gasless transaxillary approach has been increasing because of its several advantages over open thyroidectomy. This study compared the incidence of PONV in the women who underwent open or robot-assisted thyroidectomy. METHODS: This prospective, double-blinded study enrolled 170 women 20-60 years of age who were scheduled for conventional open thyroidectomy (group O) or robot-assisted thyroidectomy (group R). A standard anesthetic technique, including sevoflurane and air in oxygen, was used. During a 0-24-h postoperative period, the presence and severity of PONV (nausea, retching/vomiting), severity of pain, need for rescue antiemetics, and the degree of patient satisfaction were evaluated. RESULTS: During the 0-6-h postoperative period, the incidence of PONV and mean pain score (40.0 vs. 51.8 %and 4.2 vs. 4.8 in groups R and O, respectively) were not significantly different. At 6-24 h postoperatively, the incidence of PONV (18.8 vs. 44.7 %), severe emesis (11.8 vs. 29.4 %) and mean pain score (2.8 vs. 3.8) were significantly lower in group R compared to group O, respectively. Overall, the incidence of PONV (42.4 vs. 63.5 %) and severe emesis (20.0 vs. 43.5 %) were significantly lower in group R compared to group O, respectively. The incidence of satisfied patients 6 and 24 h after the end of anesthesia (55.3 vs. 28.2 and 82.4 vs. 58.8 %) were significantly higher in group R compared to group O, respectively. CONCLUSIONS: Robotic thyroidectomy reduces the incidence and severity of PONV compared to open thyroidectomy during a 0-24-h postoperative period.

Pediatric Application of Cuffed Endotracheal Tube.

A young child's larynx was formerly believed to be narrowest at the cricoid level, circular in section, and funnel shaped. This supported the routine use of uncuffed endotracheal tubes (ETTs) in young children despite the benefits of cuffed ETTs, such as lower risk for air leakage and aspiration. In the late 1990s, evidence supporting the pediatric use of cuffed tubes emerged largely from anesthesiology studies, while some technical flaws of the tubes remained a concern. Since the 2000s, imaging-based studies have clarified laryngeal anatomy, revealing that it is narrowest at the glottis, elliptical in section, and cylindrical in shape. The update was contemporaneous with technical advances in the design, size, and material of cuffed tubes. The American Heart Association currently recommends the pediatric use of cuffed tubes. In this review, we present the rationale for using cuffed ETTs in young children based on our updated knowledge of pediatric anatomy and technical advances.

Comparison of fiberoptic bronchoscopic intubation using silicone and polyvinyl chloride double-lumen tubes.

BACKGROUND: Direct insertion of a double-lumen tube (DLT) using a flexible fiberoptic bronchoscope (FOB) is an option for DLT intubation. The difficult process of fiberoptic intubation is that the different properties of polyvinyl chloride and silicone DLTs may affect railroading differently. Therefore, we aimed to compare intubation using polyvinyl chloride and silicone DLTs over an FOB. METHODS: Patients aged 19-75 years who required one-lung ventilation under general anesthesia were enrolled in this study. After induction of anesthesia, the anesthesiologist intubated the DLT using FOB. The primary outcome was the difficulty of railroading over the flexible FOB scaled into five grades (I, II-1, II-2, III, and IV). Additionally, the intubation time and mucosal damage were recorded. RESULTS: A total of 46 patients participated in this study, 23 each in the silicone and polyvinyl groups. The difficulty of railroading over the FOB was significantly different between the two groups (P < 0.001). In the silicone group, the grades of difficulty in railroading were limited to I and II-1; 20 patients (87%) presented no difficulty in advancing the tube. In contrast, in the polyvinyl group, 13 patients (57%) had scores of II-2 and III. Both the intubation time and mucosal damage were significantly better in the silicone group than in the polyvinyl group. CONCLUSIONS: Intubation using a silicone DLT over an FOB was easier and faster than that with a polyvinyl chloride DLT with lesser trauma around the glottis.

Comparison of silicone double-lumen tube and polyvinyl chloride single-lumen tube in fiberoptic tracheal intubation on a difficult airway model: a randomized controlled non-inferiority trial.

The management of patients with history or suspicion of difficult intubation can be challenging, especially in surgical procedures requiring one-lung ventilation. The ease of insertion of silicone double lumen tube (DLT) have previously been shown to be comparable to polyvinyl single lumen tube (SLT) in fiberoptic bronchoscope (FOB) tracheal intubation. Hence, in difficult airway situation, we hypothesized that the performance of insertion of silicone DLT would also be non-inferior to polyvinyl SLT in FOB intubation. We used a neck collar to mimic patients with difficult airway. 80 patients who required one-lung ventilation were enrolled in a prospective, randomized, non-inferiority trial. Patients were randomly allocated to the DLT or SLT groups (SLT with bronchial blocker). Neck collar was supplied to all patients before FOB intubation. The time of insertion for FOB, railroading, tracheal intubation, and total procedure were measured. The difficulty of railroading was evaluated in 4 grades. In the DLT group, the railroading was significantly shorter and easier comparing to the SLT group. The total procedure was also simpler and faster in the DLT group. While simulated difficult airways may not fully replicate actual difficult airways, we suggest that fiberoptic intubation with silicone DLT could be a feasible first-line option for patients with expected difficult airways requiring lung separation, unless the size of the DLT relative to the patient's airway is problematic.Trial registration: NCT03392766.

The effect of cuff pressure on postoperative sore throat after Cobra perilaryngeal airway.

PURPOSE: The cuff volume of the Cobra perilaryngeal airway (CobraPLA) is larger than that of other alternative airway devices and makes it difficult to predict the effect of cuff pressure on the perilaryngeal mucosa. We tested the hypothesis that adjustment of the cuff pressure of the CobraPLA could reduce the incidence of postoperative sore throat (POST). METHODS: After induction of general anesthesia and insertion of the CobraPLA by standardized method, the cuff pressure was set to 60 cmH(2)O (group C, n = 87) or adjusted to minimal seal-up pressure +5 cmH(2)O (group A, n = 87). The frequency and severity (0, none; 1, mild; 2, moderate; 3, severe) of throat soreness, pain, discomfort, and adverse effects were evaluated 1 and 24 h after removal of the CobraPLA. RESULTS: Incidence of moderate POST in group C was higher than that in group A (11% vs. 2%, P = 0.021) whereas the overall POST incidence was not different between the two groups (31% vs. 20%, P = 0.092). The inflated air volume of group A was different from that of group C (41 vs. 50 ml, P = 0.009). CONCLUSIONS: Adjustment of cuff pressure reduces the incidence of moderate POST after use of the CobraPLA.

Prevention of Bradycardia during Spinal Anesthesia under Dexmedetomidine Sedation in Older Adults.

Older adults exhibit reduced physiological responses to beta-adrenergic stimulation and parasympathetic inhibition. This study aimed to investigate the effect of reducing the incidence of bradycardia in the atropine and ephedrine pretreatment group compared to the control group in older adults who received spinal anesthesia with intravenous dexmedetomidine. Overall, 102 older adults aged over 65 years were randomly divided into three groups, and saline (control group), atropine at 0.5 mg (atropine group), and ephedrine at 8 mg (ephedrine group) were administered intravenously to each group as pretreatment. Immediately after spinal anesthesia, dexmedetomidine loading and study drug injections were commenced. The primary outcome was the incidence of bradycardia (<50 beats per min) within 60 min following dexmedetomidine loading. The incidence of bradycardia requiring atropine treatment was significantly higher in the control group than in the atropine and ephedrine groups (27.3% vs. 6.1% and 8.8%, respectively; p = 0.035), and no difference was noted between the atropine and ephedrine groups. Therefore, if ephedrine or atropine is selected and used according to the patient's condition and clinical situation, it may be helpful in preventing bradycardia during spinal anesthesia using dexmedetomidine in older patients.

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.

Comparison of learning direct laryngoscopy using a McGrath videolaryngoscope as a direct versus indirect laryngoscope: a randomized controlled trial.

OBJECTIVE: Tracheal intubation using a direct laryngoscope is difficult to teach. The McGrath videolaryngoscope, a Macintosh-like device with a camera, can be used as a direct laryngoscope to educate novices under supervision using the screen. We compared the effect on Macintosh laryngoscopy skills following training with a McGrath videolaryngoscope as a direct versus indirect laryngoscope. METHODS: Thirty-seven participants were randomized into direct and indirect groups according to the training method using a McGrath videolaryngoscope. Participants attempted Macintosh direct laryngoscopy in normal and difficult airway scenarios. The primary endpoint was the intubation time, and the rate of successful intubation, dental trauma, and difficulty were secondary outcomes. RESULTS: The intubation time after education decreased significantly in both groups and was significantly shorter in the direct group than in the indirect group across time. The difficulty degree in the direct group was lower than that in the indirect group across time; however, the rate of dental trauma was not significantly different. CONCLUSION: Both direct and indirect laryngoscopy using a McGrath videolaryngoscope improved the performance of Macintosh direct laryngoscopy in novices, while direct laryngoscopy using a McGrath videolaryngoscope demonstrated better educational effects than indirect laryngoscopy.Registered at ClinicalTrials.gov (NCT03471975).

Discrete change in volatile anesthetic sensitivity in mice with inactivated tandem pore potassium ion channel TRESK.

BACKGROUND: We investigated the role of tandem pore potassium ion channel (K2P) TRESK in neurobehavioral function and volatile anesthetic sensitivity in genetically modified mice. METHODS: Exon III of the mouse TRESK gene locus was deleted by homologous recombination using a targeting vector. The genotype of bred mice (wild type, knockout, or heterozygote) was determined using polymerase chain reaction. Morphologic and behavioral evaluations of TRESK knockout mice were compared with wild-type littermates. Sensitivity of bred mice to isoflurane, halothane, sevoflurane, and desflurane were studied by determining the minimum alveolar concentration preventing movement to tail clamping in 50% of each genotype. RESULTS: With the exception of decreased number of inactive periods and increased thermal pain sensitivity (20% decrease in latency with hot plate test), TRESK knockout mice had healthy development and behavior. TRESK knockout mice showed a statistically significant 8% increase in isoflurane minimum alveolar concentration compared with wild-type littermates. Sensitivity to other volatile anesthetics was not significantly different. Spontaneous mortality of TRESK knockout mice after initial anesthesia testing was nearly threefold higher than that of wild-type littermates. CONCLUSIONS: TRESK alone is not critical for baseline central nervous system function but may contribute to the action of volatile anesthetics. The inhomogeneous change in anesthetic sensitivity corroborates findings in other K2P knockout mice and supports the theory that the mechanism of volatile anesthetic action involves multiple targets. Although it was not shown in this study, a compensatory effect by other K2P channels may also contribute to these observations.

Continuous Fentanyl Background Infusion Regimen Optimised by Patient-Controlled Analgesia for Acute Postoperative Pain Management: A Randomised Controlled Trial.

Owing to a lack of studies investigating the effect of adjustments in fentanyl background infusion (BI) with patient-controlled analgesia (PCA) on postoperative analgesia, we evaluated three BI regimens with fentanyl PCA for acute postoperative pain management. This randomised controlled trial enrolled 105 patients, who were assigned to three parallel groups: constant rate BI of 2 mL/h (CRBI group); time-scheduled decremental BI of 6, 2 and 1 mL/h (TDBI group); and BI rates optimised to the demand of PCA (POBI group). The incidence of insufficient analgesia, visual analogue scale (VAS) pain score and side effects were evaluated. The incidence of insufficient analgesia in the post-anaesthesia care unit was lower in the TDBI and POBI groups than the CRBI group. Incidence of insufficient analgesia in the ward was lower in the POBI group than the CRBI group. Postoperative VAS scores were significantly lower in the TDBI and POBI groups for up to 4 h and 24 h, respectively, compared with the CRBI group. Side effects and infused fentanyl dose were highest in the CRBI group. Adjusting BI rate based on time or patient demands could improve postoperative analgesia and reduce side effects. Compared to a constant BI rate, PCA-optimised BI achieved higher patient satisfaction.

Receptor mediation and nociceptin inhibition of bradykinin-induced plasma extravasation in the knee joint of the rat.

OBJECTIVE AND DESIGN: The aim was to investigate the signaling mechanisms and regulation of bradykinin (BK)-induced inflammation in rat knee joint. MATERIALS AND METHODS: Knee joints of anesthetized rats were perfused with BK (0.1-1.0 microM), and synovial plasma extravasation (PE) was evaluated by spectrophotometrical measurement of Evans Blue leakage. To examine the signaling pathway, B1 antagonist [des-Arg10]-HOE140 (0.1-1.0 microM) and B2 antagonist HOE140 (0.05-1.0 microM), calcitonin gene-related peptide (CGRP) antagonist CGRP8-37 (0.5-1.0 microM), prostaglandin E2 antagonist AH-6809 (0.1-1.0 microM), and histamine H1 antagonist mepyramine (0.1-1.0 microM) were used. Nociceptin (0.0001-1.0 microM) and antagonist J-113397 were tested for modulation of BK-induced PE. The analyses were compared side-by-side with 5-hydroxytryptamine-induced PE. RESULTS: BK perfusion dose-dependently induced PE, which was blocked by HOE140, CGRP8-37, AH-6809, and mepyramine. It was also inhibited by nociceptin, which could be reversed by antagonist J-113397. In contrast, 5-hydroxytryptamine-induced PE was biphasically regulated by nociceptin and was not antagonized by CGRP8-37. CONCLUSIONS: BK-induced PE is mediated by B2 receptors and may involve CGRP, prostaglandin, and histamine pathways. BK-induced PE is inhibited by nociceptin through the activation of ORL1 receptors. There are differences between BK- and 5-hydroxytryptamine-induced inflammation in signaling and modulation.

Intravascular flow patterns in transforaminal epidural injections: a comparative study of the cervical and lumbar vertebral segments.

BACKGROUND: Transforaminal epidural injection (TEI) is commonly used in the treatment of radicular pain. However, there have been many published cases of serious complications after a TEI, occurring most often in cervical levels. One of the presumptive reasons for this complication is inadvertent intravascular injection. We sought to identify the incidence of intravascular injections in cervical and lumbar spinal segments during TEI. METHODS: All patients with radicular symptoms or herpes zoster-associated pain underwent cervical and lumbar TEIs (LTEIs) prospectively by one of the authors. After an ideal needle position was confirmed by biplanar fluoroscopy, 3 mL of a mixture containing nonionic contrast and normal saline was continuously injected at the rate of 0.3-0.5 mL/s with real-time fluoroscopic visualization. RESULTS: One hundred eighty-two TEIs were performed. Fifty-six cases (30.8%) showed intravascular spreading patterns, 45 cases occurring during a cervical TEI (CTEI) and 11 during a LTEI. The incidences of simultaneous perineural and vascular injection in cervical and LTEIs were 52.1% and 9%, respectively, and pure vascular flow pattern rates in cervical and LTEIs were 11.3% and 0.9%, respectively. CONCLUSION: The incidence of vascular injection in CTEIs is significantly higher than in LTEIs, suggesting that CTEIs should be performed more cautiously. Furthermore, the vascular injection rate of CTEIs is much higher than that previously reported. This finding suggests the need for a proper volume of contrast injection (3 mL) to detect vascular flow, especially in simultaneous perineural and vascular injections.