Yon Hee Shim

Magnesium sulfate prevents remifentanil-induced postoperative hyperalgesia in patients undergoing thyroidectomy.

BACKGROUND: In a randomized, double-blind, prospective study, we investigated whether an intraoperative high versus low dose of remifentanil increased postoperative hyperalgesia and whether magnesium can prevent remifentanil-induced hyperalgesia. METHODS: Ninety patients undergoing thyroidectomy were randomly assigned to 1 of 3 groups. Remifentanil was intraoperatively infused at 0.05 &mgr;g/kg/min (group LO) or 0.2 &mgr;g/kg/min (groups HI and HM). Patients in group HM received MgSO4 30 mg/kg at induction followed by an intraoperative infusion of 10 mg/kg/h. Mechanical pain thresholds on the forearm and periincisional area were assessed by von Frey filament the evening before surgery and postoperatively at 24 and 48 hours. Pain measured on a verbal numerical rating scale (VNRS) (0–10) and additional analgesics were recorded in the postanesthesia care unit postoperatively at 6, 24, and 48 hours. RESULTS: There was a significantly greater decrease in pain threshold on the periincisional area at 24 and 48 hours postoperatively in group HI, as compared with the other 2 groups. The 95% confidence intervals for the mean difference in pain thresholds on the periincisional area at 24 and 48 hours postoperatively were 0.31 to 1.11 and 0.36 to 1.14 for group HI versus group LO, 0.45 to 1.26 and 0.54 to 1.32 for group HI versus group HM (values are log10 of force in milligrams). The change in pain threshold on the forearm was similar among the groups. Group HI had significantly higher VNRS scores (median [interquartile range], 3 [2–4]) than group LO (2 [1–3] and group HM (2 [1–3]) at 48 hours postoperatively. The 95% confidence intervals for median difference in VNRS score at 48 hours postoperatively were 1 to 2 for group HI versus group LO and 0 to 2 for group HI versus group HM. There were no significant differences in the number of patients who requested rescue analgesics in the postoperative anesthesia care unit and general ward during 48 hours postoperatively among the 3 groups. CONCLUSIONS: A relatively high dose of intraoperative remifentanil enhances periincisional hyperalgesia. Intraoperative MgSO4 prevents remifentanil-induced hyperalgesia. However, hyperalgesia did not reach clinical relevance in terms of postoperative pain or analgesic consumption in patients undergoing thyroidectomy.

Pregabalin reduces post-operative pain after mastectomy: a double-blind, randomized, placebo-controlled study

Background: Pregabalin is used for the treatment of neuropathic pain and has shown analgesic efficacy in post‐operative pain. The aim of this randomized, double‐blinded, placebo‐controlled trial (Clinical Trials.gov ID NCT00938548) was to investigate the efficacy and safety of pregabalin for reducing post‐operative pain in patients after mastectomy.

Pregabalin reduces post-operative pain after mastectomy

Background: Pregabalin is used for the treatment of neuropathic pain and has shown analgesic efficacy in post‐operative pain. The aim of this randomized, double‐blinded, placebo‐controlled trial (Clinical Trials.gov ID NCT00938548) was to investigate the efficacy and safety of pregabalin for reducing post‐operative pain in patients after mastectomy.

Incidence and Risk Factors of Acute Kidney Injury After Thoracic Aortic Surgery for Acute Dissection

BACKGROUND Previous studies have reported a high incidence of acute kidney injury (AKI) after thoracic aortic surgery in heterogeneous patient cohorts, including various aortic diseases and the use of deep hypothermic circulatory arrest. Moderate hypothermia with cerebral perfusion makes deep hypothermia nonessential, but can make end organs susceptible to ischemia during circulatory arrest. We investigated the incidence and risk factors of AKI after thoracic aortic surgery with and without moderate hypothermic circulatory arrest for acute dissection. METHODS We reviewed the medical records of 98 patients undergoing graft replacement of the thoracic aorta for acute dissection between 2008 and 2011 at a university hospital. Acute kidney injury was defined by RIFLE criteria, which is based on serum creatinine or glomerular filtration rate. RESULTS The mean age was 55±15 years. The surgical procedures, 96% of which were emergencies, involved the ascending aorta (67%), aortic arch (41%), descending aorta (41%), and aortic valve (5%). Moderate hypothermic circulatory arrest was performed in 75%. The overall incidence of AKI was 54%, and 11% of 98 patients required renal replacement therapy. Thirty-day mortality increased with AKI severity (p=0.002). Independent risk factors for AKI were long cardiopulmonary bypass duration (>180 minutes; odds ratio, 7.50; p=0.008) and preoperative serum creatinine level (odds ratio, 8.43; p=0.016). CONCLUSIONS Acute kidney injury was common after thoracic aortic surgery for acute dissection with or without moderate hypothermic circulatory arrest and worsened 30-day mortality. Prolonged cardiopulmonary bypass and increased preoperative serum creatinine were independent risk factors for AKI, but moderate hypothermic circulatory arrest was not.

Sugammadex versus neostigmine reversal of moderate rocuronium-induced neuromuscular blockade in Korean patients

Background Rapid and complete reversal of neuromuscular blockade (NMB) is desirable at the end of surgery. Sugammadex reverses rocuronium-induced NMB by encapsulation. It is well tolerated in Caucasian patients, providing rapid reversal of moderate (reappearance of T2) rocuronium-induced NMB. We investigated the efficacy and safety of sugammadex versus neostigmine in Korean patients. Methods This randomized, safety assessor-blinded trial (NCT01050543) included Korean patients undergoing general anesthesia. Rocuronium 0.6 mg/kg was given prior to intubation with maintenance doses of 0.1-0.2 mg/kg as required. Patients received sugammadex 2.0 mg/kg or neostigmine 50 µg/kg with glycopyrrolate 10 µg/kg to reverse the NMB at the reappearance of T2, after the last rocuronium dose. The primary efficacy endpoint was the time from sugammadex or neostigmine administration to recovery of the train-of-four (TOF) ratio to 0.9. The safety of these medications was also assessed. Results Of 128 randomized patients, 118 had evaluable data (n = 59 in each group). The geometric mean (95% confidence interval) time to recovery of the TOF ratio to 0.9 was 1.8 (1.6, 2.0) minutes in the sugammadex group and 14.8 (12.4, 17.6) minutes in the neostigmine group (P < 0.0001). Sugammadex was generally well tolerated, with no evidence of residual or recurrence of NMB; four patients in the neostigmine group reported adverse events possibly indicative of inadequate NMB reversal. Conclusions Sugammadex was well tolerated and provided rapid reversal of moderate rocuronium-induced NMB in Korean patients, with a recovery time 8.1 times faster than neostigmine. These results are consistent with those reported for Caucasian patients.

Hyperglycemia Attenuates Myocardial Preconditioning of Remifentanil

BACKGROUND Hyperglycemia attenuates cardioprotection by remifentanil-preconditioning in ischemia-reperfusion in vivo in diabetic rats. However, the effects of hyperglycemia in cultured ventricular myocytes remains unknown. Therefore, we examined the in vitro effects of hyperglycemia on hypoxia-reoxygenation (H/R) and cardioprotection from remifentanil-preconditioning in isolated neonatal rat ventricular myocytes (NRVMs), including effects on apoptotic signaling pathways and Ca(2+) homeostasis. MATERIALS AND METHODS NRVMs were cultured in medium with 5.5 mM (normoglycemia) or 25.5 mM glucose for one day. Then, NRVMs in H/R groups were exposed to 1 h of hypoxia and 5 h of reoxygenation with or without remifentanil-preconditioning at 1 μM. Cell viability, apoptosis, and Ca(2+) homeostasis were assessed by MTT assay, caspase-3 assay, confocal microscopy and immunoblots. RESULTS In normoglycemia, remifentanil-preconditioning improved the viability of cardiomyocytes (P < 0.01) and prevented the increase of caspase-3 activity and Ca(2+) overload after H/R injury (P < 0.05). In addition, decrease in Akt, ERK1/2, and Bcl-2, and the increase in Bax by H/R was attenuated by remifentanil-preconditioning (P < 0.05). However, in hyperglycemia, the viability was partially impaired after H/R but not improved by remifentanil-preconditioning. Apoptotic activity, Ca(2+) concentration, and apoptotic kinases except Akt were not affected by either H/R or remifentanil-preconditioning under hyperglycemia. Akt phosphorylation was decreased by H/R but not restored by remifentanil preconditioning. CONCLUSIONS Remifentanil preconditioning under normoglycemia renders NRVMs resistant to H/R injury by reducing apoptosis and intracellular Ca(2+) concentrations. The mechanism appears to be modulation of apoptotic signaling. However, hyperglycemia mitigates H/R injury in NRVMs, and may reduce the protective effect of remifentanil-preconditioning that may be associated with the Akt pathways.

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.

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.

Effects of propofol on the expression of matric metalloproteinases in rat cardiac fibroblasts after hypoxia and reoxygenation

BACKGROUND Propofol is known to protect the myocardium against ischaemia/reperfusion (I/R) injury through its antioxidant and anti-inflammatory properties. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are involved in cell migration and invasion, and mediate tissue remodelling during I/R injury. They are regulated by various mechanisms including oxidative stress and AKT and ERK pathways. We investigated whether propofol affected the expression of MMPs and subsequent cell migration and invasion and the signalling pathways involved in primary rat cardiac fibroblasts undergoing hypoxia and reoxygenation. METHODS The phosphorylation of ERK and AKT signalling pathways was examined by western blot analysis in rat primary cardiac fibroblasts after hypoxia and reoxygenation. mRNA expression of MMP and TIMPS was analysed by real-time PCR, and proteolytic activities of MMP-2 and -9 were assessed. The effects of propofol on migration, invasion, wound healing, and cell proliferation activity were evaluated after reoxygenation. RESULTS Propofol induced AKT and ERK1/2 activation. Subsequent activation of MMPs resulted in increased cell migration, invasion, and wound-healing activity under hypoxia-reoxygenation, which was decreased by LY294002 (AKT inhibitor) and U0126 (ERK inhibitor) in rat cardiac fibroblasts. However, propofol had no effect on proliferation or viability of cardiac fibroblasts after hypoxia-reoxygenation. CONCLUSIONS Propofol affected the expression of MMPs and TIMPs and subsequently induced cell migration and invasive ability, through activation of the ERK and AKT signalling pathway in hypoxia-reoxygenated rat cardiac fibroblasts.

Estimation of the length of the nares-vocal cord

The nasal route is preferred for fiberoptic intubation. Placing a lubricated endotracheal tube through the nostril can guide the fiberoptic scope towards the larynx. It would be helpful for optimal visualization of the vocal cord when the scope is passed through the endotracheal tube if the length of nares-vocal cord (NV length) could be predicted and the tip of the endotracheal tube could be placed close to the vocal cord. In this study we measured the NV length and examined the relationship between the NV length and various external measurements. Using a fiberoptic scope, the NV lengths were measured in 50 male and 45 female patients scheduled to undergo elective surgery under general anesthesia. In addition, the distances from the lateral border of the nares to tragus of the ear (NE distance) and to the angle of the mandible (NM distance) were measured. The age, height, and weight of all the patients were recorded. The NV length of the males was 18.3 ± 0.8 cm, and that of the females was 16.3 ± 0.7 cm. The relationship between the NV length and body height (P < 0.001, r = 0.755) and the NE distance (P < 0.001, r = 0.636) showed a significant correlation but NM distance did not (P = 0.075). The length of the NV cord can be predicted using the body height or the NE distance.