Analgesic effectiveness of continuous versus single-injection adductor canal block in addition to continuous popliteal sciatic nerve block for bimalleolar and trimalleolar ankle fracture surgery: Prospective randomized controlled trial.

BACKGROUND: The adductor canal block is a well-known procedure for controlling postoperative pain after medial malleolus fracture surgery. Continuous nerve block is a viable option for blocking pain for a longer period although the literature on this subject is scarce. Therefore, this study aimed to compare continuous adductor canal block (cACB) group to single-injection adductor canal block (sACB) group in those with bimalleolar or trimalleolar ankle fractures. The procedure was performed in addition to a continuous sciatic nerve block for postoperative pain relief and patient satisfaction. METHODS: The study included 57 patients who had bimalleolar or trimalleolar ankle fractures and underwent open reduction and internal fixation between August 2016 and June 2018. Each patient received a continuous sciatic nerve block and was divided into two groups: those who received cACB and those who received sACB. Each postoperative pain was scored at 4, 8, 12, 24, 48, and 72 h after surgery. Additionally, the consumption of rescue medications and patient satisfaction were evaluated. RESULTS: The two groups displayed no disparity in medial side ankle pain at 4 h and 8 h after surgery, but significantly higher pain in the sACB group at 12, 24, 48, and 72 h after surgery. However, there was no difference in the pain at the lateral side of ankle and consumption of rescue medication. In addition, the cACB group showed more satisfaction than the sACB group did. CONCLUSION: CACB is better than sACB in terms of postoperative pain control and patient satisfaction. cACB can be used for postoperative pain control in ankle fractures involving the medial malleolus. LEVEL OF EVIDENCE: Prospective Randomized Controlled Trial, Level 2.

The Effect of Sex on the Remimazolam Dosage Required for Successful i-gel Supraglottic Airway Insertion with Remifentanil in Non-Paralyzed Patients: An Up-and-Down Sequential Allocation Trial.

(1) Background: The physiological and pharmacological variations between men and women are known to influence drug efficacy. The objective of this study was to determine the 50% and 95% effective doses (ED50 and ED95) of remimazolam required for i-gel supraglottic airway (ISA) insertion under remifentanil infusion without neuromuscular blocking agents (NMBAs) in both males and females. (2) Methods: Patients aged 19-65 years, scheduled for general anesthesia using ISA, were enrolled in this study. Patients were divided into two groups based on their sex. The anesthesia process began with a remifentanil infusion targeting an effect-site concentration of 3.0 ng/mL, accompanied by a remimazolam injection. The initial remimazolam dose was 0.25 mg/kg, and it was adjusted with a step size of 0.05 mg/kg based on the outcome of ISA insertion in the preceding patient. (3) Results: The ED50 of remimazolam (mean ± standard error) was 0.28 ± 0.02 mg/kg in the male group and 0.18 ± 0.02 mg/kg in the female group (p < 0.001). Additionally, ED95, which was calculated using the isotonic regression method, was significantly comparable between the male and female groups (male: 0.35 mg/kg, 95% confidence interval [CI] = 0.34-0.35; female: 0.29 mg/kg, 95% CI = 0.25-0.30). (4) Conclusions: This study showed that both the ED50 and the ED95 of remimazolam for successful ISA insertion was higher for men than that for women. Therefore, while using remimazolam alongside remifentanil infusion without NMBAs for ISA insertion, one should consider the patient's sex for appropriate dosing.

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.

Effective dose of remimazolam co-administered with remifentanil to facilitate I-gel insertion without neuromuscular blocking agents: an up-and-down sequential allocation trial.

BACKGROUND: Remimazolam is a new anesthetic drug developed and is an ultra-short-acting agent with rapid onset and offset. The pharmacology of this drug seems to be ideal for short surgeries eligible for I-gel insertion. Therefore, this study aimed to determine the optimal bolus dose of remimazolam for I-gel insertion when co-administered with remifentanil without neuromuscular blocking agents (NMBAs). METHODS: Patients aged 19-65 years with American Society of Anesthesiologists physical status I or II scheduled for general anesthesia were enrolled. The first dose of remimazolam was 0.15 mg/kg and remifentanil was co-administered at an effect-site concentration (Ce) of 3.0 ng/mL. The dose of remimazolam for the following patient was decreased or increased by 0.05 mg/kg depending on the success or failure of I-gel insertion in the previous patient. RESULTS: The remimazolam bolus dose required for successful I-gel insertion in 50% of adult patients using modified Dixon's up-and-down method with remifentanil Ce 3.0 ng/mL and no NMBAs was 0.280 ± 0.048 mg/kg. Isotonic regression analysis showed that the 50% and 95% effective doses were 0.244 (83% confidence interval [CI] 0.213-0.313) mg/kg and 0.444 (95% CI 0.436-0.448) mg/kg, respectively. The mean time to loss of consciousness (Modified Observer's Assessment of Alertness/Sedation score < 2) was 52.2 s. Three patients (12.0%) showed a reduction in systolic blood pressure of more than 30% from baseline. CONCLUSIONS: Selecting the appropriate dose of remimazolam/remifentanil without NMBAs makes it feasible to insert the I-gel. TRIAL REGISTRATION: This study protocol was registered at http://cris.nih.go.kr (KCT0007801, 12th, October, 2022).

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.

Determination of the 95% effective dose of remimazolam to achieve loss of consciousness during anesthesia induction in different age groups.

BACKGROUND: Remimazolam is a new ultra short-acting benzodiazepine originally developed as an improved version of midazolam. Recent studies have demonstrated non-inferiority of remimazolam to propofol in general anesthesia. However, to date, few studies have investigated the induction bolus dose of remimazolam required to achieve general anesthesia. We aimed to determine the 95% effective dose (ED95) of remimazolam bolus required to achieve loss of consciousness (LOC) and the appropriate doses for different age groups. METHODS: Patients aged 20-79 years with the American Society of Anesthesiologists physical status of I or II were enrolled in this study. A total of 120 patients were included representing young, middle-aged, and elderly groups. Loss of eyelash reflex and verbal response after the administration of remimazolam was considered successful LOC. The ED95 of remimazolam was determined using a biased coin up-and-down design with sequential allocation and the isotonic regression method. RESULTS: The ED95 of remimazolam for induction of general anesthesia was 0.367 mg/kg (95% CI [0.277, 0.392]) in the young group, 0.369 mg/kg (95% CI [0.266, 0.394]) in the middle-aged group, and 0.249 mg/kg (95% CI [0.199, 0.288]) in the elderly group. During the study period, none of the patients required rescue medications for hypotension or bradycardia. CONCLUSIONS: This study investigated the ED95 of remimazolam bolus for anesthesia induction. The precise dosing of the ED95 can help maintain hemodynamic stability during the induction of anesthesia.

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.

Efficacy and Safety of Ultrasound-Guided Supraclavicular Brachial Plexus Block during Angioplasty of Dysfunctional Arteriovenous Access: A Prospective, Randomized Single-Center Clinical Trial.

PURPOSE: To evaluate the efficacy and safety of the ultrasound-guided supraclavicular brachial plexus block (BPB) during angioplasty of dysfunctional arteriovenous access. MATERIALS AND METHODS: Eighty study participants with dysfunctional arteriovenous access were enrolled in this prospective, randomized clinical trial between November 2016 and February 2018. Eighty patients were randomized to either the ultrasound-guided supraclavicular BPB group (mean age ± standard deviation [SD], 65.1 ± 12.4; male:female = 17:23) or the no regional anesthesia group (mean age ± SD, 64.0 ± 11.7; male:female = 25:15). Pain was assessed on the 10-point Visual Analogue Scale. Participant satisfaction was examined. Six-month clinical follow-up was done to evaluate arteriovenous access patency and long-term complications. RESULTS: The BPB group showed a lower average pain score than the control group (mean ± SD, 0.9 ± 1.9 vs 6.4 ± 2.5; P < .001). Participant satisfaction (mean ± SD, 2.8 ± 0.5 vs 2.1±0.8; P < .001) was also higher in the BPB group. Six-month patency was 65% (26/40) in the BPB group and 59% (23/39) in the control group, with no significant difference between the 2 groups (P = .59). No major immediate or delayed complications were observed. CONCLUSIONS: Ultrasound-guided BPB is highly effective in reducing pain during angioplasty of dysfunctional arteriovenous access with an acceptable safety profile.

Thirty-Day Postoperative Outcomes Following Sugammadex Use in Colorectal Surgery Patients; Retrospective Study.

PURPOSE: Sugammadex rapidly reverses muscle relaxation compared to acetylcholinesterase inhibitors. The long-term outcomes of sugammadex, however, are not well known. We compared 30-day postoperative outcomes following sugammadex and acetylcholinesterase inhibitor use in colorectal surgery patients. PATIENTS AND METHODS: Colorectal surgical patients older than 21 were included in this retrospective study, and were dichotomized according to use of reversal agents, sugammadex (group S), and acetylcholinesterase inhibitor (group A). We assessed 30-day postoperative outcomes, including total length of hospital stay, length of postoperative hospital stay, readmission rate, and delayed discharge rate. Additional parameters included postanesthetic care unit stay time, time to first successful oral intake, unforeseen intensive care unit (ICU) admission rate, postoperative pulmonary complications, and mortality. RESULTS: Among a total of 585 patients, 157 patients remained in each group after propensity score matching. Total length of hospital stay, length of postoperative hospital stay, and readmission rates did not differ between the two groups, while the incidence of delayed discharge was significantly lower in group S (23 (15%) vs. 40 (25%), p = 0.017). Other outcomes did not differ between the two groups. CONCLUSION: We found no difference in 30-day postoperative outcomes following sugammadex and acetylcholinesterase inhibitor use. The only difference between these treatments was the associated incidence of delayed discharge, which was lower in group S.

Postoperative Analgesic Effect of Ultrasound-Guided Intermediate Cervical Plexus Block on Unipolar Sternocleidomastoid Release With Myectomy in Pediatric Patients With Congenital Muscular Torticollis: A Prospective, Randomized Controlled Trial.

BACKGROUND AND OBJECTIVES: Unipolar sternocleidomastoid release with myectomy (USRM) for correction of congenital muscular torticollis in pediatric patients produces moderate to severe postoperative pain. The objective of this trial was to examine the effect of ultrasound-guided intermediate cervical plexus block on postoperative pain after USRM. METHODS: Thirty-two patients (1-7 years old) were enrolled in this parallel-group, patient- and observer-blinded, randomized controlled trial. In the block group, 0.25% ropivacaine (0.2 mL/kg) was injected into the interfascial plane between the sternocleidomastoid muscle and the prevertebral fascia under ultrasound guidance at the fourth to fifth cervical vertebral level. The primary outcome measure was the face, legs, activity, cry, and consolability (FLACC) score at 5 minutes after entering the postanesthesia care unit (PACU), and secondary outcome measures were the FLACC score at discharge from the PACU and 3, 6, and 24 hours after operation and the use of rescue analgesic in the PACU and ward. RESULTS: The FLACC score at 5 minutes after admission to the PACU was significantly reduced (3 vs 8; median difference, 4; 95% confidence interval, 1-7; P = 0.044), and the fentanyl dose and the number of patients requiring rescue analgesics in the PACU were significantly lower (0.0 vs 0.5 µg/kg, P = 0.014; 5 [29.4%] vs 12 [75.0%], P = 0.032) in the block than in the control group. However, after discharge from PACU, there was no difference in FLACC scores and use of rescue analgesics between groups. CONCLUSIONS: Ultrasound-guided intermediate cervical plexus block decreased immediate postoperative pain and opioid requirements in the PACU in pediatric patients who underwent USRM. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02651311.

Adductor canal block versus femoral nerve block combined with sciatic nerve block as an anesthetic technique for hindfoot and ankle surgery: A prospective, randomized noninferiority trial.

BACKGROUND: A femoral nerve block (FNB) in combination with a sciatic nerve block (SNB) is commonly used for anesthesia and analgesia in patients undergoing hindfoot and ankle surgery. The effects of FNB on motor function, related fall risk, and rehabilitation are controversial. An adductor canal block (ACB) potentially spares motor fibers in the femoral nerve, but the comparative effect on hindfoot and ankle surgeries between the 2 approaches is not yet well defined. We hypothesized that compared to FNB, ACB would cause less weakness in the quadriceps and produce similar pain scores during and after the operation. METHODS: Sixty patients scheduled for hindfoot and ankle surgeries (arthroscopy, Achilles tendon surgery, or medial ankle surgery) were stratified randomized for each surgery to receive an FNB (FNB group) or an ACB (ACB group) combined with an SNB. The primary outcome was the visual analog scale (VAS) pain score at each stage. Secondary outcomes included quadriceps strength, time profiles (duration of the block procedure, time to full anesthesia and time to full recovery), patients' analgesic requirements, satisfaction, and complications related to peripheral nerve blocks such as falls, neurologic symptoms, and local anesthetic systemic toxicity were evaluated. The primary outcome was tested for the noninferiority of ACB to FNB, and the other outcomes were tested for the superiority of each variable between the groups. RESULTS: A total of 31 patients received an ACB and 29 received an FNB. The VAS pain scores of the ACB group were not inferior during and after the operation compared to those of the FNB group. At 30 minutes and 2 hours after anesthesia, patients who received an ACB had significantly higher average dynamometer readings than those who received a FNB (34.2 ±â€Š20.4 and 30.4 ±â€Š23.7 vs 1.7 ±â€Š3.7 and 2.3 ±â€Š7.4, respectively), and the results were similar at 24 and 48 hours after anesthesia. There were no differences between the 2 groups with regard to time profiles and patient satisfaction. No complications were noted. CONCLUSION: ACB preserved quadriceps muscle strength better than FNB, without a significant difference in postoperative pain. Therefore, ACB may be a good alternative to FNB for reducing the potential fall risk.

Effect of sex differences in remifentanil requirements for the insertion of a laryngeal mask airway during propofol anesthesia: A prospective randomized trial.

BACKGROUND: Remifentanil can improve insertion of a laryngeal mask airway (LMA) during induction with propofol. Recently, it has been suggested that there is a sex difference in opioid requirements for this procedure. The purposes of this study were to determine the effective effect-site concentration (Ce) of remifentanil for the facilitation of LMA insertion in male and female patients during propofol anesthesia without neuromuscular blockade and to evaluate whether there are sex differences in the Ce of remifentanil required for successful LMA insertion. METHODS: Forty-eight patients (24 male, 24 female) with American Society of Anesthesiologists physical status 1 or 2, aged 20 to 60 years, scheduled for minor orthopedic surgery under general anesthesia were enrolled. Anesthesia was induced by target-controlled infusion (TCI) of propofol and remifentanil. The target Ce of propofol was 5 µg/mL initially and was reduced to 3.5 µg/mL after loss of consciousness. The Ce of remifentanil given to each patient was determined by the response of the previously tested patient using 0.5 ng/mL as a step size. The 1st patient was tested at a Ce of 3.0 ng/mL of remifentanil. Successful LMA insertion was defined as smooth insertion without patient movement or significant resistance to mouth opening. RESULTS: The effective Ce of remifentanil required for successful LMA insertion on 50% of occasions (effective effect-site concentration for 50% [EC50]) as estimated by Dixon method was significantly lower in women (2.18 ±â€Š0.35 ng/mL) than in men (2.82 ±â€Š0.53 ng/mL) (P = 0.02). Using the isotonic regression method, the effective Ce of remifentanil required for successful LMA insertion on 95% of occasions (EC95) (95% confidence interval [CI]) was significantly lower in women (3.38 [3.0-3.48] ng/mL) than in men (3.94 [3.80-3.98] ng/mL). CONCLUSION: The Ce of remifentanil required to facilitate successful LMA insertion is higher during propofol induction by TCI in men than in women. When using remifentanil for LMA insertion, patient sex should be taken into account for appropriate dosing.

Analgesic Effects of Ultrasound-Guided Serratus-Intercostal Plane Block and Ultrasound-Guided Intermediate Cervical Plexus Block After Single-Incision Transaxillary Robotic Thyroidectomy: A Prospective, Randomized, Controlled Trial.

BACKGROUND AND OBJECTIVES: Single-incision transaxillary robotic thyroidectomy (START) requires substantial tissue disruption, which produces moderate-to-severe pain in the axilla and neck areas during the early postoperative period. This study aimed to investigate the analgesic effects of ultrasound-guided serratus-intercostal plane blocks and intermediate cervical plexus blocks (CPBs) on the early postoperative pain after START. METHODS: We randomized 22 patients to undergo either ultrasound-guided serratus-intercostal plane and intermediate CPBs (the block group, n = 11) or to not undergo any block (the control group, n = 11). We compared postoperative axillary pain, postoperative neck pain, and analgesic use between the groups during the first 24 hours. The rescue analgesics were intravenous fentanyl (0.5 µg/kg) in the postanesthesia care unit, and intravenous ketorolac tromethamine (30 mg) in the general ward. RESULTS: The block group showed consistently lower pain scores than the control group in the axillary area in the first 24 hours and in the neck area only in the first 3 hours after surgery. The numbers (proportions) of patients who required analgesics were 11 (100%) in the control group and 6 (54.5%) in the block group during the first 24 hours (P = 0.035). No adverse effect was observed related to the peripheral nerve blocks. CONCLUSIONS: After START, a serratus-intercostal plane block performed at the level of the third rib was an effective analgesic technique for axillary pain; however, the clinical effectiveness of intermediate CPB for neck pain may be limited.

Effect of total intravenous anaesthesia and prophylactic ramosetron on postoperative nausea and vomiting after thyroidectomy: A prospective, randomized controlled study.

OBJECTIVE: To investigate the effect of combined prophylactic ramosetron and total intravenous anaesthesia (TIVA) on postoperative nausea and vomiting (PONV), compared with sevoflurane anaesthesia without prophylactic antiemetics, in female patients undergoing thyroidectomy. METHODS: Female patients were randomized between the sevoflurane group (anaesthesia maintained with sevoflurane) or TIVA + ramosetron group (TIVAR; 0.3 mg ramosetron just before anaesthesia induction, remifentanil and propofol anaesthesia). Incidence and severity of PONV and use of rescue antiemetics were recorded during the first 24 h after surgery. RESULTS: In the early postoperative period (0-6 h), the incidence of PONV, severe emesis and rescue antiemetic use were significantly lower in the TIVAR group (n = 36) than in the sevoflurane group (n = 36). In the late postoperative period (6-24 h), the incidence of severe emesis was significantly lower in the TIVAR group than in the sevoflurane group. CONCLUSIONS: A combination of TIVA and prophylactic ramosetron decreases early PONV and late postoperative severe emesis compared with sevoflurane anaesthesia.

Correction of target-controlled infusion following wrong selection of emulsion concentrations of propofol.

BACKGROUND: We investigated the correction methods following wrong-settings of emulsion concentrations of propofol as a countermeasure against erroneous target-controlled infusions (TCI). METHODS: TCIs were started with targeting 4.0 µg/ml of effect-site concentration (Ceff) of propofol, and the emulsion concentrations were selected for 2.0% instead of 1.0% (FALSE1-2, n = 24), or 1.0% instead of 2.0% (FALSE2-1, n = 24). These wrong TCIs were corrected at 3 min after infusion start. During FALSE1-2, the deficit was filled up while injecting after equilibrium (n = 12), or while overriding (n = 12). During FALSE2-1, the overdose was evacuated while targeting Ceff (n = 12) or targeting plasma concentration (Cp) (n = 12). The gravimetrical measurements of TCI reproduced the Cp and Ceff using simulations. The reproduced Ceff at 3 min (Ceff-3min) and the time to be normalized within ± 5% of target Ceff (T±5%), were compared between the correction methods. RESULTS: During the wrong TCI, Ceff-3min was 1.98 ± 0.01 µg/ml in FALSE1-2, and 7.99 ± 0.05 µg/ml in FALSE2-1. In FALSE1-2, T±5% was significantly shorter when corrected while overriding (3.9 ± 0.25 min), than corrected after equilibrium (6.9 ± 0.05 min) (P < 0.001). In FALSE2-1, T±5% was significantly shorter during targeting Cp (3.6 ± 0.04 min) than targeting Ceff (6.7 ± 0.15 min) (P < 0.001). CONCLUSIONS: The correction methods, based on the pharmacokinetic and pharmacodynamic characteristics, could effectively and rapidly normalize the wrong TCI following erroneously selections of the emulsion concentration of propofol.

Arrangements of the intravenous parallel infusions with anti-reflux valves decreasing occlusion alarm delay.

BACKGROUND: The methods of arrangement of combined intravenous parallel infusions using anti-reflux valve (ARV), with and without anti-syphon valve (ASV) that could decrease occlusion alarm delay were investigated. METHODS: Occlusion challenge tests were mainly performed as bench experiments of four kinds of multiple parallel infusions (10 ml/h and 50 ml/h infusions), which were connected at the proximal or distal portion of ARV, with or without ASV. Alarm threshold was set to 1000 mmHg. Occlusion alarm delays and the compliances of the infusion systems were compared among groups. RESULTS: Without ASV, compared to 10 ml/h infusion alone distal to anti-reflux valve, 50 ml/h infusion distal to anti-reflux valve reduced the mean alarm delay from 416 ± 7 s to 81 ± 3 s (P < 0.001). Compared to 50 ml/h infusion alone, combined 10 ml/h and 50 ml/h infusion distal to ARV prolonged the alarm delay from 81 ± 3 s to 133 ± 6 s (P < 0.001). However, combined infusions distal to ARV with ASV significantly reduced the alarm delay from 133 ± 6 s to 74 ± 5 s (P < 0.001), and also reduced the compliance of the infusion system from 2.31 ± 0.12 to 1.20 ± 0.08 µl/mmHg (P < 0.001). CONCLUSIONS: The infusion setup of faster infusion rate, lower compliant system using ASV could effectively decrease occlusion alarm delay during multiple intravenous parallel infusions using ARV.

Intravenous lidocaine pretreatment with venous occlusion for reducing microemulsion propofol induced pain: comparison of three doses of lidocaine.

OBJECTIVE: Pretreatment with intravenous 40 mg or 0.5 mg/kg lidocaine with venous occlusion is recommended to prevent pain following injection of lipid emulsion propofol. This approach is not sufficient to prevent pain from the injection of microemulsion propofol. The present study investigated whether a higher dose of lidocaine pretreatment with venous occlusion would be more effective for reducing pain following injection of microemulsion propofol compared with 40 mg lidocaine. METHODS: Patients undergoing elective surgery were randomly assigned to one of three groups: pretreatment with 40 mg (group L40), 60 mg (group L60) or 80 mg (group L80) lidocaine intravenously with venous occlusion, followed by injection with microemulsion propofol 1 min later. Pain was assessed on a four-point scale (severe, moderate, mild, none) based on physical responses to the injection. RESULTS: A total of 68 patients were included in the final analysis. Pain severity and incidence were significantly lower in patients in group L60 and L80 compared with patients in group L40. There were no statistically significant differences in pain incidence or severity between group L60 and group L80. CONCLUSIONS: Pretreatment with 60 mg lidocaine intravenously with venous occlusion may be the most effective minimum dose for reducing injection pain following microemulsion propofol administration for induction of anaesthesia.

Effect of tracheal lidocaine on intubating conditions during propofol-remifentanil target-controlled infusion without neuromuscular blockade in day-case anesthesia.

BACKGROUND: Lidocaine is a useful intravenous and topical adjunct to facilitate tracheal intubation. We evaluated the effect of tracheal lidocaine on tracheal intubating conditions without neuromuscular blocking agent and hemodynamics during anesthesia induction with propofol and remifentanil target-controlled infusion (TCI). METHODS: Fifty patients, aged 18-60 years, scheduled for closed reduction of fractured nasal bone were randomly assigned to the control group (n = 25) or lidocaine group (n = 25). Anesthesia was induced with propofol-remifentanil TCI with the effect-site concentration of 5 µg/ml and 5 ng/ml. Four minutes after the start of propofol-remifentanil TCI, 4% lidocaine or saline 3 ml was instilled to larynx and trachea, and intubation was performed 1 min later. Acceptable intubation was defined as excellent or good intubating conditions. Hemodynamic data, induction and recovery profiles were recorded. RESULTS: Intubating condition was clinically acceptable in 13 out of 25 (52%) patients in the control group and in 22 out of 25 (88%) in the lidocaine group, and there was a significant difference between the two groups in regard to acceptable intubating conditions (P = 0.005). Mean arterial pressure change over time was significantly different between the two groups. There were no significant differences in the heart rate between the two groups. CONCLUSIONS: This study demonstrated that laryngotracheal administration of 4% lidocaine could increase the percentage of acceptable conditions for tracheal intubation during propofol and remifentanil anesthesia without neuromuscular blockade.

Distribution range of cervical interlaminar epidural injections: a comparative study with 2.5 mL, 5 mL, and 10 mL of contrast.

BACKGROUND: Cervical interlaminar epidural injection (CIEI) is widely used in the management of acute or chronic neck and upper extremity pain. There is no consensus regarding the optimal volume of solution to be used for CIEI. STUDY DESIGN: Randomized, double blind controlled trial. OBJECTIVE: The purpose of this study was to evaluate how many spinal segments would be covered with different volumes of contrast medium, given by fluoroscopically guided CIEI, in efforts to establish the optimal volume of medication with consideration of clinical pathologic lesions. METHODS: One hundred and twenty-six CIEI were performed at C7-T1 in 133 patients. All patients were divided into 3 groups (A, B, and C) according to the amount of contrast medium used: 2.5 mL for group A, 5 mL for group B, and 10 mL for group C. The extent of contrast medium spread was determined by anteroposterior and lateral view under fluoroscopy. LIMITATION: We did not evaluate the clinical outcomes with pain measurements during the study period. RESULTS: The total number of vertebral segments of contrast media spread and spreading range of caudad or cephalad were significantly different among the 3 groups (P < 0.001). However, groups B and C in cephalad spreading and groups A and B in caudad spreading did not show any significant difference. A proportion of the patients with a cephalad spread of up to C4 and C2 in group A (59.5% and 31%) was significantly different from that in the other 2 groups (92.9% and 69.1% in group B and 97.6% and 73.8% in group C) (P < 0.001). CONCLUSION: Five mL for CIEI at C7-T1 could be an optimal volume for distribution to the lower cervical spine for degenerative cervical spinal diseases, as well as to the upper cervical spine for head and facial pain.

Accuracy of cardiac output measurements during off-pump coronary artery bypass grafting: according to the vessel anastomosis sites.

BACKGROUND: During beating heart surgery, the accuracy of cardiac output (CO) measurement techniques may be influenced by several factors. This study was conducted to analyze the clinical agreement among stat CO mode (SCO), continuous CO mode (CCO), arterial pressure waveform-based CO estimation (APCO), and transesophageal Doppler ultrasound technique (UCCO) according to the vessel anastomosis sites. METHODS: This study was prospectively performed in 25 patients who would be undergoing elective OPCAB. Hemodynamic variables were recorded at the following time points: during left anterior descending (LAD) anastomosis at 1 min and 5 min; during obtuse marginal (OM) anastomosis at 1 min and 5 min: and during right coronary artery (RCA) anastomosis at 1 min and 5 min. The variables measured including the SCO, CCO, APCO, and UCCO. RESULTS: CO measurement techniques showed different correlations according to vessel anastomosis site. However, the percent error observed was higher than the value of 30% postulated by the criteria of Critchley and Critchley during all study periods for all CO measurement techniques. CONCLUSIONS: In the beating heart procedure, SCO, CCO and APCO showed different correlations according to the vessel anastomosis sites and did not agree with UCCO. CO values from the various measurement techniques should be interpreted with caution during OPCAB.