Tae Dong Kweon

Effects of fentanyl pretreatment on the QTc interval during propofol induction

Prolongation of the corrected QT (QTc) interval is associated with various anaesthetic drugs. The QTc prolongation may become more exacerbated during laryngoscopy and intubation, which is possibly caused by sympathetic stimulation. The aim of this study was to investigate the effects of fentanyl on the QTc interval during propofol induction in healthy patients. The patients were randomly allocated to receive either fentanyl (n = 25) or saline (n = 25) before induction. The QTc interval was significantly prolonged immediately after intubation in control group compared to preceding values, but it did not change in the fentanyl group. The number of patients with the prolonged QTc interval exceeding 20 ms immediately after intubation compared to the baseline values was 14 in the control group and seven in the fentanyl group. In conclusion, pretreatment with fentanyl 2 μg.kg−1 significantly attenuated QTc prolongation associated with laryngoscopy and tracheal intubation during propofol induction.

The effect of bolus administration of remifentanil on QTc interval during induction of sevoflurane anaesthesia.

Stimulation of the sympathetic nervous system associated with tracheal intubation causes corrected QT (QTc) interval prolongation. We postulated that the use of remifentanil during induction of anaesthesia might prevent this. Sixty unpremedicated, ASA grade 1 patients were selected and randomly allocated to receive either saline (group S), remifentanil 0.5 μg.kg−1 (group R 0.5) or remifentanil 1.0 μg.kg−1 (group R1.0) 1 min before laryngoscopy. The QTc interval was significantly prolonged immediately following intubation in group S and group R0.5, but it remained stable in group R1.0, compared with the QTc interval just before laryngoscopy. It is concluded that the administration of remifentanil 1.0 μg.kg−1 before intubation can prevent the prolongation of the QTc interval associated with tracheal intubation during induction of anaesthesia with sevoflurane.

Effects of target concentration infusion of propofol and tracheal intubation on QTc interval

This study was designed to evaluate the effect of target controlled infusion of propofol on QTc interval and tracheal intubation. Twenty‐five unpremedicated, ASA class I or II patients were selected and target concentration infusion of propofol at 5 μg.ml−1 was used throughout the study. The QTc interval was measured before anaesthetic induction (baseline, T1), 10 min after propofol infusion (T2), immediately after tracheal intubation (T3), and 1 min after tracheal intubation (T4). The QTc interval increased significantly at 10 min after the propofol infusion started compared to baseline (p = 0.003). After tracheal intubation, the QTc interval was further increased when compared to that at T2 (p < 0.0001). The increased QTc interval was within normal limit and no patient had an arrhythmia. In conclusion, although statistically significant, the increase in QTc interval was too small to be clinically significant during propofol infusion. However, the combination of propofol and tracheal intubation must be used carefully in patients with prolonged QTc interval.

Cervical Ganglion Block Attenuates the Progression of Pulmonary Hypertension via Nitric Oxide and Arginase Pathways

It has been recognized that the sympathetic nervous system is activated in pulmonary arterial hypertension (PAH), and abnormal sympathetic hyperactivity leads to worsening of PAH via endothelial dysfunction. The purpose of this study was to examine whether sympathetic ganglion block (SGB) can treat PAH by increasing the availability of nitric oxide (NO). PAH was induced in rats by 50 mg/kg of subcutaneous monocrotaline. After 2 weeks, daily injections of ropivacaine into the left superior cervical ganglion were repeated for 14 days (monocrotaline-SGB group). Monocrotaline group received sham SGB with saline, whereas control group received saline instead of monocrotaline. PAH was evident in monocrotaline group, with right ventricular systolic pressures (47±4 mm Hg) that were higher than those of controls (17±2 mm Hg), whereas SGB significantly attenuated monocrotaline-induced PAH (35±4 mm Hg). The right/left ventricular mass ratios exhibited similar changes to those seen with right ventricular pressures. Heart rate variability showed significantly higher sympathetic activity in the monocrotaline group. Microscopy revealed a higher proportion of muscular arteries with thicker medial walls in the monocrotaline group, which was attenuated by SGB. Monocrotaline induced arginase hyperactivity, which was in turn decreased by SGB-induced endothelial NO synthase activation. SGB restored monocrotaline-induced hypoactivity of superoxide dismutase. In conclusion, SGB could suppress PAH and the remodeling of pulmonary arteries via inactivation of arginase and reciprocal elevation of NO bioavailability, thus attenuating disproportionate hyperactivation of the sympathetic nervous system.

ORIGINAL ARTICLE: Ultrasonographic evaluation of the femoral vein in anaesthetised infants and young children

We investigated the cross‐sectional area of the femoral vein and its relationship to the femoral artery at two anatomical levels, in infants and children. Sixty‐six subjects were allocated to one of two groups: infants (< 1 year, n = 31) or children (1–6 years, n = 35). After induction of general anaesthesia, the femoral vein was evaluated by ultrasound with the patients’ legs at 30° and 60° of abduction and their hips externally rotated. In each position, measurements were taken at the level of the inguinal crease and 1 cm below the crease. Hip rotation with 60° leg abduction decreased femoral artery overlap at the level of the inguinal crease in both infants (p = 0.013) and children (p = 0.003). Thus, the optimal place for femoral vein cannulation in paediatric patients seems to be at the level of the inguinal crease with 60° leg abduction and external hip rotation.

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.

Ultrasonographic evaluation of the femoral vein in anaesthetised infants and young children

We investigated the cross‐sectional area of the femoral vein and its relationship to the femoral artery at two anatomical levels, in infants and children. Sixty‐six subjects were allocated to one of two groups: infants (< 1 year, n = 31) or children (1–6 years, n = 35). After induction of general anaesthesia, the femoral vein was evaluated by ultrasound with the patients’ legs at 30° and 60° of abduction and their hips externally rotated. In each position, measurements were taken at the level of the inguinal crease and 1 cm below the crease. Hip rotation with 60° leg abduction decreased femoral artery overlap at the level of the inguinal crease in both infants (p = 0.013) and children (p = 0.003). Thus, the optimal place for femoral vein cannulation in paediatric patients seems to be at the level of the inguinal crease with 60° leg abduction and external hip rotation.

Effects of reverse Trendelenburg position and inguinal compression on femoral vein cross-sectional area in infants and young children

This study evaluated the effects of the reverse Trendelenburg position and additional inguinal compression on the cross‐sectional area of the femoral vein in paediatric patients. Seventy subjects were allocated to two groups: the infants group and the children group. Cross‐sectional area of the femoral vein was measured just below the inguinal ligament using ultrasound. Three measurements were obtained for each patient: (i) supine, (ii) reverse Trendelenburg position and (iii) reverse Trendelenburg position with inguinal compression. In the infants group, femoral vein cross‐sectional area increased by a mean (SD) of 21.1 (15.2) % in the reverse Trendelenburg position and by 60.7 (30.8) % in the reverse Trendelenburg position with inguinal compression; whereas in the children group, femoral vein cross‐sectional area increased by 24.7 (15.8) % in the reverse Trendelenburg position and by 100.3 (50.7) % in the reverse Trendelenburg position with inguinal compression. Inguinal compression in the reverse Trendelenburg position offers a useful means of increasing femoral vein cross‐sectional area in paediatric patients.

Significance of the injection timing of ephedrine to reduce the onset time of rocuronium.

We postulated that the onset time of rocuronium can be accelerated effectively if it is administered at the time when the effect of ephedrine on cardiac output has reached its maximum. Seventy‐five male, anaesthetised, patients were randomly allocated to three groups. Ephedrine 70 μg.kg−1 was administered at 4 min (Early) or 30 s (Late) before administering rocuronium. The control group received saline at 4 min and at 30 s before rocuronium. The onset time of rocuronium in the Early group was significantly shorter than in the Control group, but there was no difference in the onset time between the Late and Control groups. There were no significant differences in the intubating conditions of the three groups. Ephedrine 70 μg.kg−1 can reduce the onset time of rocuronium effectively if rocuronium is administered at 4 min following the ephedrine injection, when the effect of ephedrine on cardiac output is expected to reach its maximum.

Intravenous glucose–insulin–potassium during off-pump coronary artery bypass surgery does not reduce myocardial injury

Background:  This randomized, double‐blind, placebo‐controlled study was designed to determine whether an intra‐operative, intravenous infusion of glucose–insulin–potassium (GIK) could be helpful in the prevention of myocardial ischemia and in the maintenance of intra‐operative cardiac performance in patients undergoing off‐pump coronary artery bypass (OP‐CAB) surgery.