Kyeong Tae Min

The effect of pneumoperitoneum in the steep Trendelenburg position on cerebral oxygenation.

Background: daVinci® robot‐assisted laparoscopic radical prostatectomy (RALP) requires pneumoperitoneum in the steep Trendelenburg position, which results in increased intracranial pressure and cerebral blood flow. The aim of this study was to evaluate the effect of pneumoperitoneum in a 30° Trendelenburg position on cerebral oxygenation using regional cerebral oxygen saturation (rSO2).

Effects of Beach-Chair Position and Induced Hypotension on Cerebral Oxygen Saturation in Patients Undergoing Arthroscopic Shoulder Surgery

PURPOSE We investigated the effects of the beach-chair position and induced hypotension on regional cerebral oxygen saturation (rSO(2)) in patients undergoing arthroscopic shoulder surgery by using near-infrared spectroscopy. METHODS Twenty-eight patients scheduled for arthroscopic shoulder surgery were enrolled prospectively. After induction of anesthesia, mechanical ventilation was controlled to maintain Paco(2) at 35 to 40 mm Hg. Anesthesia was maintained with sevoflurane and remifentanil. After radial artery cannulation, mean arterial pressure (MAP) was measured at the external auditory meatus level and maintained between 60 and 65 mm Hg. The rSO(2) was measured by use of near-infrared spectroscopy. MAP and rSO(2) were recorded at the following times: before induction (T(0)), immediately after induction (T(1) [baseline]), after beach-chair position (T(2)), immediately after induced hypotension (T(3)), 1 hour after induced hypotension (T(4)), and after supine position at the end of surgery (T(5)). Cerebral desaturation was defined as a reduction in rSO(2) to less than 80% of baseline value for 15 seconds or greater. RESULTS A total of 27 patients were evaluated until the end of this study. The MAP at T(2) was significantly lower than that at T(1). The MAP values at T(3) and T(4) were significantly lower than those at T(1) and T(2). The rSO(2) at T(2) was significantly lower than that at T(1). Unlike the pattern of change in the MAP, there was no additional decrease in rSO(2) at T(3) and T(4). There were 2 patients who had an episode of cerebral desaturation. CONCLUSIONS The beach-chair position combined with induced hypotension significantly decreases rSO(2) in patients undergoing shoulder arthroscopic surgery under general anesthesia. LEVEL OF EVIDENCE Level IV, study of nonconsecutive patients without consistently applied reference gold standard.

Learning by computer simulation does not lead to better test performance than textbook study in the diagnosis and treatment of dysrhythmias

STUDY OBJECTIVE To compare computer-based learning with traditional learning methods in studying advanced cardiac life support (ACLS). DESIGN Prospective, randomized study. SETTING University hospital. MEASUREMENTS Senior medical students were randomized to perform computer simulation and textbook study. Each group studied ACLS for 150 minutes. Tests were performed 1 week before, immediately after, and 1 week after the study period. Testing consisted of 20 questions. All questions were formulated in such a way that there was a single best answer. Each student also completed a questionnaire designed to assess computer skills, as well as satisfaction with and benefit from the study materials. MAIN RESULTS Test scores improved after both textbook study and computer simulation study in both groups, although the improvement in scores was significantly higher for the textbook group only immediately after the study. There was no significant difference between groups in their computer skill and satisfaction with the study materials. The textbook group reported greater benefit from study materials than did the computer simulation group. CONCLUSIONS Studying ACLS with a hard-copy textbook may be more effective than computer simulation for acquiring simple information during a brief period. However, the difference in effectiveness is likely transient.

Effect of Ginseng Saponins on the Recombinant Serotonin Type 3A Receptor Expressed in Xenopus Oocytes: Implication of Possible Application as an Antiemetic

OBJECTIVES Nausea and vomiting are the most frequently reported side-effects by patients who are given general anesthesia perioperatively and patients with cancer who undergo chemotherapy or radiotherapy. Serotonin (5-hydroxytryptamine, 5HT) type 3A receptor (5HT(3A) receptor) is known to mediate nausea and vomiting and its antagonists have been used effectively to prevent and/or reduce the incidence and severity of nausea and vomiting. However, the adverse effects on cardiac function, such as QT interval prolongation, limit their routine use by these patients. This study was designed to elucidate the effect of ginseng saponins on the recombinant 5HT(3A) receptor expressed in the xenopus oocyte. DESIGN After in vitro transcription of the recombinant human 5HT(3A) receptor in the Xenopus laevis oocyte, we examined Panax ginseng saponins (total saponin [TS], panaxadiol saponin [PD] fraction, panaxatriol saponin [PT] fraction, and ginsenoside-Rb1 and -Rg1) for their ability to inhibit current flow through the 5HT(3A) receptor using the voltage-clamp technique. RESULTS All saponin fractions (TS, PD, PT fraction, as well as ginsenoside-Rb1 and -Rg1) inhibited the peak current induced by the agonist 5HT on the 5HT(3A) receptor in a concentration-dependent, reversible, and voltage-independent manner. The PT fraction inhibited 5HT-induced currents in 5HT(3A) receptor more than the PD fraction; meanwhile, there was a similar degree of inhibition between ginsenoside-Rg1 and -Rb1, the main substitutes of PT fraction and PD saponin fractions, respectively. CONCLUSIONS These results indicate that ginseng saponins, especially PT fraction, have substantial inhibitory effects on the recombinant 5HT(3A) receptor, suggesting that some of the specific types of ginsenoside might have an antagonistic action against 5HT(3A) receptor related to nausea and vomiting.

A single dose of esmolol blunts the increase in bispectral index to tracheal intubation during sevoflurane but not desflurane anesthesia.

Activation of the peripheral nerve system by endotracheal intubation is accompanied by an increase in bispectral index (BIS). Esmolol produces a dose-dependent attenuation of the adrenergic response to endotracheal intubation. Desflurane increases sympathetic nerve activity and plasma norepinephrine relative to sevoflurane. The authors hypothesized that esmolol might blunt the BIS response to endotracheal intubation more during sevoflurane anesthesia than desflurane anesthesia. In this double blind, randomized study, after the induction of anesthesia, patients were mask-ventilated with either sevoflurane or desflurane (end-tidal 1 minimum alveolar concentration) and received normal saline or esmolol (0.5 mg/kg) 1 minute before intubation (sevoflurane-control, sevoflurane-esmolol, desflurane-control, and desflurane-esmolol groups, n=20/group). BIS, mean arterial pressure, and heart rate were measured before the induction of anesthesia (awake), before esmolol injection (time point -1), immediately before intubation (time point 0), and every minute for 5 minutes after tracheal intubation (time point 1 to 5). Compared with preintubation, esmolol attenuated the increase in BIS at 1 minute after intubation during sevoflurane anesthesia (5.1% for esmolol and 31.7% for control) but not during desflurane anesthesia (28.6% for esmolol and 30.8% for control). Mean arterial pressure and heart rate increased after intubation in all groups but the changes were greater in the control groups than the esmolol groups. In conclusion, a single dose of esmolol blunted the increase in BIS to tracheal intubation during sevoflurane but not desflurane anesthesia.

Determination of EC95 of remifentanil for smooth emergence from propofol anesthesia in patients undergoing transsphenoidal surgery.

Background: In patients undergoing pituitary surgery using a transsphenoidal approach, anesthesia emergence should be smooth with minimal coughing. Recent studies demonstrated that a target-controlled infusion of remifentanil effectively suppresses coughing induced by the endotracheal tube. We investigated the EC95 of remifentanil for smooth emergence without coughing from propofol anesthesia in patients undergoing transsphenoidal hypophysectomy. Materials and Methods: A total of 41 patients undergoing transsphenoidal hypophysectomy, aged 20 to 65 years, with an ASA physical status of I or II, were enrolled. For all participants, anesthesia was induced and maintained with a target-controlled infusion of remifentanil and propofol using predicted effect-site concentration (Ce). A biased coin design up-and-down sequential allocation and isotonic regression method were used to determine the remifentanil EC95 to prevent emergence coughing. In addition, we observed recovery profiles after anesthesia. Results: According to the study design, 19 patients received remifentanil 2.6 ng/mL Ce and 22 patients received a lower Ce, ranging from 1.0 to 2.2 ng/mL. The EC95 of remifentanil to prevent coughing was estimated as 2.51 ng/mL (95% confidence interval, 2.28-2.57 ng/mL). Despite the exclusion of 1 case because of delayed emergence, 17 of 18 patients receiving 2.6 ng/mL of remifentanil had bradypnea (<10 breaths/min) until 3 minutes after extubation. However, end-tidal carbon dioxide was maintained below 55 mm Hg during anesthetic emergence and respiratory rate recovered within 20 minutes of admission to the postanesthetic care unit. Conclusions: The EC95 of remifentanil for smooth emergence from anesthesia was 2.51 ng/mL after transsphenoidal hypophysectomy.

Ultrasonography of the optic nerve sheath to assess intracranial pressure changes after ventriculo‐peritoneal shunt surgery in children with hydrocephalus: a prospective observational study

The optic nerve sheath diameter has been verified by various clinical studies as a non‐invasive indicator of intracranial hypertension. The aim of this study was to compare the optic nerve sheath diameter before and immediately after ventriculo‐peritoneal shunt surgery in children with hydrocephalus. We analysed transorbital ultrasonographic images recorded after induction of anaesthesia and 30 min after shunt insertion in 34 children, measuring the optic nerve sheath diameters using a linear ultrasound probe. The mean (SD) optic nerve sheath diameters were 5.4 (0.6) mm (right) and 5.3 (0.7) mm (left) before surgery and 4.4 (0.5) mm (right) and 4.5 (0.7) mm (left) after surgery (p < 0.0001 for before and after comparisons for both eyes). The technique allows rapid and non‐invasive assessment of intracranial pressure to guide appropriate postoperative management.

Comparison of Dexmedetomidine and Remifentanil on Airway Reflex and Hemodynamic Changes during Recovery after Craniotomy

Purpose During emergence from anesthesia for a craniotomy, maintenance of hemodynamic stability and prompt evaluation of neurological status is mandatory. The aim of this prospective, randomized, double-blind study was to compare the effects of dexmedetomidine and remifentanil on airway reflex and hemodynamic change in patients undergoing craniotomy. Materials and Methods Seventy-four patients undergoing clipping of unruptured cerebral aneurysm were recruited. In the dexmedetomidine group, patients were administered dexmedetomidine (0.5 µg/kg) for 5 minutes, while the patients of the remifentanil group were administered remifentanil with an effect site concentration of 1.5 ng/mL until endotracheal extubation. The incidence and severity of cough and hemodynamic variables were measured during the recovery period. Hemodynamic variables, respiration rate, and sedation scale were measured after extubation and in the post-anesthetic care unit (PACU). Results The incidence of grade 2 and 3 cough at the point of extubation was 62.5% in the dexmedetomidine group and 53.1% in the remifentanil group (p=0.39). Mean arterial pressure (p=0.01) at admission to the PACU and heart rate (p=0.04 and 0.01, respectively) at admission and at 10 minutes in the PACU were significantly lower in the dexmedetomidine group. Respiration rate was significantly lower in the remifentanil group at 2 minutes (p<0.01) and 5 minutes (p<0.01) after extubation. Conclusion We concluded that a single bolus of dexmedetomidine (0.5 µg/kg) and remifentanil infusion have equal effectiveness in attenuating coughing and hemodynamic changes in patients undergoing cerebral aneurysm clipping; however, dexmedetomidine leads to better preservation of respiration.

Effect of Charcoal Filter on the Emergence from Sevoflurane Anesthesia in a Semi-Closed Rebreathing Circuit

Purpose A charcoal filter attached within the anesthetic circuit has been shown to efficiently adsorb halothane or isoflurane, thus hastening anesthetic recovery in low or minimal flow system. This study was intended to demonstrate whether the charcoal filter enhances the recovery time from sevoflurane anesthesia using a semi-closed circuit system. Materials and Methods Thirty healthy patients scheduled for elective surgery under sevoflurane anesthesia were randomly assigned to the charcoal filter or control group. Upon completion of surgery, the end-tidal concentration of sevoflurane was maintained at 2.0 vol%. A charcoal filter was attached to the expiratory limb of the breathing circuit of charcoal filter group subjects. After sevoflurane was discontinued, ventilation was controlled with the same minute volume as the intra-operative period at a fresh gas flow rate of 5 L·min-1 with 100% O2. The elimination kinetics of sevoflurane from end-tidal concentration, Bispectral index and times of eye opening and extubation were obtained. Results The exponential time constant (τ) of alveolar sevoflurane concentration in the charcoal filter group was significantly shorter than that in the control group (1.7±0.5 vs. 2.5±1.1 min, p=0.008). The charcoal filter hastened rapid eye opening (11.1±3.8 vs. 14.8±3.0 min, p=0.007) and extubation (11.9±3.9 vs. 15.3±3.2 min, p=0.014), compared to the control group. Conclusion A charcoal filter enhances the recovery from sevoflurane anesthesia with a semi-closed rebreathing circuit.

Effect-site concentration of propofol target-controlled infusion at loss of consciousness in intractable epilepsy patients receiving long-term antiepileptic drug therapy.

BackgroundPropofol dose requirement for loss of consciousness (LOC) in epilepsy patients would be probably affected by increasing factors [development of tolerance, up-regulated &ggr;-aminobutyric acid (GABAA) receptors, or antiepileptic activity of propofol] and reducing factors [synergistic interaction between propofol and antiepileptic drugs (AEDs) or reduced neuronal mass in cortex] in complex and counteracting ways. Therefore, we determined the effect-site concentration (Ce) of propofol for LOC in intractable epilepsy patients receiving chronic AEDs in comparison with non-epilepsy patients. MethodsNineteen epilepsy patients receiving long-term AEDs therapy and 20 non-epilepsy patients, with the age of 20 to 65 years, were enrolled. The epilepsy patients took their prescribed AEDs until the morning of the operation. Ce of propofol for LOC was determined with isotonic regression method with bootstrapping approach following Dixons up-and-down allocation. The study was carried out before surgical stimulation. ResultsIsotonic regression showed that estimated Ce50 and Ce95 of propofol for LOC were lower in epilepsy group [2.88 &mgr;g/mL (83% confidence interval, 2.82-3.13 &mgr;g/mL) and [3.43 &mgr;g/mL (95% confidence interval, 3.28-3.47 &mgr;g/mL)] than in non-epilepsy group [3.38 &mgr;g/mL (83% confidence interval, 3.17-3.63 &mgr;g/mL) and 3.92 &mgr;g/mL (95% confidence interval, 3.80-3.97 &mgr;g/mL)] with bootstrapping approach. Mean Ce50 of propofol of epilepsy group was also lower than that of non-epilepsy group without statistical significance (2.8240.19 &mgr;g/mL vs 3.16±0.38 &mgr;g/mL, P=0.056). ConclusionsFor anesthetic induction of epilepsy patients with propofol target-controlled infusion, Ce may need to be reduced by 10% to 15% compared with non-epilepsy patients.