Chul Ho Chang

Comparison of the laryngeal view during intubation using Airtraq and Macintosh laryngoscopes in patients with cervical spine immobilization and mouth opening limitation.

Background For patients suspicious of cervical spine injury, a Philadelphia cervical collar is usually applied. Application of Philadelphia cervical collar may cause difficult airway. The aim of this study was to evaluate the laryngeal view and the success rate at first intubation attempt of the Airtraq and conventional laryngoscopy in patients with simulated cervical spine injury after application of a Philadelphia cervical collar. Methods Anesthesia was induced with propofol, remifentanil, and rocuronium. After a Philadelphia cervical collar applied, patients were randomly assigned to tracheal intubation with an Airtraq (Group A, n = 25) or with conventional laryngoscopy (Group L, n = 25). Measurements included intubation time, success rate of first intubation attempt, number of intubation attempts, and percentage of glottic opening (POGO) score. Mean blood pressure and heart rate were also recorded at baseline, just before and after intubation. Results The success rate of the first attempt in Group A (96%) was significantly greater than with the Group L (40%). POGO score was significantly greater in Group A (84 ± 20%) than in Group L (6 ± 11%). The duration of successful intubation at first tracheal intubation attempt and hemodynamic changes were not significantly different between the two groups. Conclusions The Airtraq offers a better laryngeal view and higher success rate at first intubation attempt in patients who are applied with a Philadelphia cervical collar due to suspicion of cervical spine injury.

The displacement of the tracheal tube during robot-assisted radical prostatectomy.

Background and objective Robot-assisted prostatectomy requires pneumoperitoneum in a steep Trendelenburg position, which may induce endobronchial intubation or accidental extubation. The aim of the study was to evaluate the effect of pneumoperitoneum in 30° Trendelenburg position on the displacement of the tracheal tube and to measure the changes in trachea length using fiberoptic bronchoscope. Methods Thirty male patients scheduled for robot-assisted radical prostatectomy were enrolled. After induction of general anaesthesia, the distance between the vocal cords and the tracheal tube tip (ΔVE), between the tracheal tube tip and the carina (ΔEC) and between the vocal cords and the carina (ΔVC) was measured using a fiberoptic bronchoscope before and 10 min after pneumoperitoneum in neutral position (T1 and T2, respectively), and 2 h after pneumoperitoneum in 30° Trendelenburg position (T3). Results The ΔVC and ΔEC decreased significantly 10 min after pneumoperitoneum in neutral position (T2) and 2 h after pneumoperitoneum in Trendelenburg position (T3) compared with those before pneumoperitoneum in neutral position (T1) (all P < 0.001). The changes in ΔVE were not statistically significant. Conclusion The confirmation of the tracheal tube position is recommended after pneumoperitoneum in steep Trendelenburg position during robot-assisted prostatectomy because the displacement of the tracheal tube may result in endobronchial intubation due to shortening of the carina-to-tube tip distance.

Optimal end-tidal sevoflurane concentration for the removal of the laryngeal mask airway in anesthetized adults

Sevoflurane provides smooth and rapid emergence from anesthesia and can be used when the removal of a laryngeal mask airway (LMA) is required in anesthetized patients. We sought to determine the optimal end-tidal concentrations of sevoflurane required for the removal of LMA in anesthetized adults. We studied 35 adults, aged 22–64 years old with an ASA physical status I or II, who were undergoing perineal surgery. General anesthesia was induced with thiopental, and the LMA was then inserted. Anesthesia was maintained with sevoflurane, oxygen, and air. After the surgery, the target concentration was maintained for at least 10 min, and then the LMA was removed. Each target concentration at the time of removal was predetermined by the Dixon up-down method (with 0.1% as a step size) starting at 1.7% end-tidal concentra-tion of sevoflurane. The LMA removal was considered successful when there was no coughing, clenching of teeth, or gross purposeful movements during or within 1 min after removal and also if there was no breath holding, laryngospasm, or desaturation after removal. The end-tidal concentration of sevoflurane to achieve successful LMA removal in 50% of adults was 0.99% ± 0.09% (mean ± sd) and in 95% of adults was 1.18% (95% confidence limits, 1.07%–1.79%). In conclusion, we have determined that LMA removal in 50% and 95% of anesthetized adults can be safely accomplished without coughing, moving, or any other airway complications at 0.99% and 1.18% end-tidal concentrations of sevoflurane.

Does the Tibial and Sural Nerve Transection Model Represent Sympathetically Independent Pain

Neuropathic pain can be divided into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Rats with tibial and sural nerve transection (TST) produce neuropathic pain behaviors, including spontaneous pain, tactile allodynia, and cold allodynia. The present study was undertaken to examine whether rats with TST would represent SMP- or SIP-dominant neuropathic pain by lumbar surgical sympathectomy. The TST model was generated by transecting the tibial and sural nerves, leaving the common peroneal nerve intact. Animals were divided into the sympathectomy group and the sham group. For the sympathectomy group, the sympathetic chain was removed bilaterally from L2 to L6 one week after nerve transection. The success of the sympathectomy was verified by measuring skin temperature on the hind paw and by infra red thermography. Tactile allodynia was assessed using von Frey filaments, and cold allodynia was assessed using acetone drops. A majority of the rats exhibited withdrawal behaviors in response to tactile and cold stimulations after nerve stimulation. Neither tactile allodynia nor cold allodynia improved after successful sympathectomy, and there were no differences in the threshold of tactile and cold allodynia between the sympathectomy and sham groups. Tactile allodynia and cold allodynia in the neuropathic pain model of TST are not dependent on the sympathetic nervous system, and this model can be used to investigate SIP syndromes.

Effect-site concentration of remifentanil to prevent cough after laryngomicrosurgery.

The aim of this study was to discover the optimal effect‐site concentration of remifentanil for cough prevention that does not delay awakening or cause respiratory depression during emergence from anesthesia with propofol and remifentanil in laryngomicrosurgery patients.

Comparison of the Efficacy of Dexmedetomidine plus Fentanyl Patient-controlled Analgesia with Fentanyl Patient-controlled Analgesia for Pain Control in Uterine Artery Embolization for Symptomatic Fibroid Tumors or Adenomyosis: A Prospective, Randomized Study

PURPOSE To investigate whether dexmedetomidine infusion could reduce opioid consumption and opioid-related side effects after uterine artery embolization (UAE). MATERIALS AND METHODS Fifty patients undergoing UAE for symptomatic leiomyomas or adenomyosis were randomized into two groups. In 25 patients, dexmedetomidine infusion was started at 0.2 μg/kg/h at 30 minutes before the procedure, followed by 0.4 μg/kg/h for 6 hours after the procedure. In another 25 patients (control group), volume-matched normal saline solution was administered. Both groups received fentanyl-based intravenous patient-controlled analgesia (PCA; fentanyl 10 μg/h with a bolus dose of 20 μg) during the 24 hours after the procedure. Nonspherical polyvinyl alcohol particles were used. Pain scores, fentanyl consumption, need for additional analgesics, and side effects were assessed for 24 hours after UAE. RESULTS Compared with the control group, patients in the dexmedetomidine group required 28% less PCA fentanyl during the 24 hours after UAE (P = .006). Numeric rating scale scores for pain (5.0±2.4 vs 7.0±2.2; P = .026) and the need for additional analgesics (two of 25 vs 17 of 25; P<.001) were lower in the dexmedetomidine group than in the control group during the first 1 hour after UAE. The incidence and severity of nausea and vomiting during the 24 hours after UAE were lower in the dexmedetomidine group than in the control group (P < .05). CONCLUSIONS The addition of dexmedetomidine infusion to fentanyl PCA provides better analgesia, fentanyl-sparing effect, and less nausea and vomiting, without significant hemodynamic instability.

Effect of caudal block on sevoflurane requirement for lower limb surgery in children with cerebral palsy.

Background:  Caudal block is a widely used technique for providing perioperative pain management in children. In this randomized double‐blinded study, we evaluated the effects of preoperative caudal block on sevoflurane requirements in children with cerebral palsy (CP) undergoing lower limb surgery while bispectral index (BIS) values were maintained between 45 and 55.

Optimal conditions for Laryngeal Mask Airway insertion in children can be determined by the trapezius squeezing test

STUDY OBJECTIVE To evaluate the trapezius squeezing test as a criterion of adequate anesthetic depth for Laryngeal Mask Airway (LMA) insertion in children without neuromuscular blocking agents. DESIGN Prospective, randomized clinical trial. SETTING Operating room of a university hospital. PATIENTS 45 ASA physical status I and II children, aged one to 6 years, undergoing minor surgical procedures. INTERVENTIONS An LMA was inserted in each child after the trapezius squeezing test turned to be negative. MEASUREMENTS Presence of coughing, gagging, gross purposeful movements, breath holding, laryngospasm, or desaturation during or within one minute of LMA insertion were recorded. Elapsed time of LMA insertion, end-tidal sevoflurane concentration, blood pressure, and heart rate values were also noted. MAIN RESULTS LMA insertion was successful in 41 patients. Elapsed time to complete insertion was 5.7 +/- 1.9 minutes, and end-tidal sevoflurane concentration was 3.6 +/- 1.1 vol%. No marked hemodynamic changes occurred in any child. CONCLUSIONS The trapezius squeezing test is a reliable clinical indicator to assess adequate anesthetic depth for LMA insertion in children without neuromuscular blocking agents.

Incidence and risk factors of postoperative nausea and vomiting in patients with Fentanyl-based intravenous patient-controlled analgesia and single antiemetic Prophylaxis

Purpose We evaluated the incidence and risk factors of postoperative nausea and vomiting (PONV) in patients with fentanyl-based intravenous patient-controlled analgesia (IV-PCA) and single antiemetic prophylaxis of 5-hydroxytryptamine type 3 (5 HT3)-receptor antagonist after the general anesthesia. Materials and Methods In this retrospective study, incidence and risk factors for PONV were evaluated with fentanyl IV-PCA during postoperative 48 hours after various surgeries. Results Four hundred-forty patients (23%) of 1878 had showed PONV. PCA was discontinued temporarily in 268 patients (14%), mostly due to PONV (88% of 268 patients). In multivariate analysis, female, non-smoker, history of motion sickness or PONV, long duration of anesthesia (>180 min), use of desflurane and intraoperative remifentanil infusion were independent risk factors for PONV. If one, two, three, four, five, or six of these risk factors were present, the incidences of PONV were 18%, 19%, 22%, 31%, 42%, or 50%. Laparoscopic surgery and higher dose of fentanyl were not risk factors for PONV. Conclusion Despite antiemetic prophylaxis with 5 HT3-receptor antagonist, 23% of patients with fentanyl-based IV-PCA after general anesthesia showed PONV. Long duration of anesthesia and use of desflurane were identified as risk factors, in addition to risk factors of Apfels score (female, non-smoker, history of motion sickness or PONV). Also, intraoperative remifentanil infusion was risk factor independent of postoperative opioid use. As the incidence of PONV was up to 50% according to the number of risk factors, risk-adapted, multimodal or combination therapy should be applied.

Liquid Heparin Anticoagulant Produces More Negative Bias in the Determination of Ionized Magnesium than Ionized Calcium

The ionized calcium level in blood is known to be falsely decreased when self-prepared liquid heparin anticoagulant is used, due to dilution and binding effects. The effect of liquid heparin on the determination of ionized magnesium is not as well understood. We compared the effect of liquid sodium heparin on the determination of ionized calcium and magnesium in 44 clinical samples using two types of user-prepared heparin syringes which differed in the amount of residual heparin from the BD Preset™ reference syringe. With the type 1 syringe, the liquid heparin was expelled once or twice such that some heparin could be left in the dead space at the syringe hub, while the liquid sodium heparin was thoroughly expelled from the type 2 syringe. The ionized magnesium levels obtained with the type 1 syringe were significantly lower than the reference value (by 0.068 mmol/L) (p < 0.0001), while the value obtained with the type 2 syringe differed less from the reference, by only 0.014 mmol/L (p < 0.0001). The heparin binding effect resulted in more negative bias in ionized magnesium (- 0.026 ± 0.032 mmol/L) than in ionized calcium (- 0.009 ± 0.042 mmol/L, p < 0.0001). In conclusion, we recommend using lyophilized, calcium-balanced, heparinized syringes for the determination of ionized magnesium and ionized calcium due to the increased negative bias in ionized magnesium determinations. When user-prepared syringes are used, the thorough evacuation of heparin solution should be strictly prescribed.