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 skin traction on cross-sectional area of the internal jugular vein in infants and young children.

Internal jugular veins (IJV) are commonly used to obtain central venous access. However percutaneous cannulation of the IJVis difficult in infants and young children because of its diminutive size. The aim of this study was to evaluate the effect of skin traction on the cross-sectional area of the IJV in anaesthetised infants (younger than one year) and young children (one to six years) using ultrasound. Sixty-seven subjects undergoing general anaesthesia were studied. The cross-sectional area of the IJV was measured at the junction of the two heads of the sternocleidomastoid using ultrasound. Skin traction was performed by stretching the skin over the puncture point with pieces of surgical tape in both cephalad and caudad directions. The measurements were made after the induction of anaesthesia with patients in the supine position and with positive pressure ventilation. Skin traction increased the maximum cross-sectional area of the IJV by 39.9 +/- 29.6% in infants and by 33.8 +/- 21.9% in children (P < 0.01). This increase might facilitate easier and safer IJV cannulation in infants and children.

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 microg.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 microg.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.

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 microg x 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.

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 microg x 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 microg x kg(-1) (group R 0.5) or remifentanil 1.0 microg x 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 microg x kg(-1) before intubation can prevent the prolongation of the QTc interval associated with tracheal intubation during induction of anaesthesia with sevoflurane.

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. METHODS: Eighty two adults undergoing elective OP-CAB surgery were randomly divided into two groups that received intravenously either 5% dextrose in water or GIK (50% dextrose in 500 ml of water; regular insulin, 125 IU; potassium, 80 mmol) at 0.75 ml/kg/h immediately before the induction of anesthesia to the end of surgery. To evaluate myocardial damage, creatine kinase MB and troponin T were measured before surgery, immediately after arrival in the intensive care unit and on the first post-operative day. To assess cardiac performance, hemodynamic data were obtained before and after the induction of anesthesia, before and after the bypass graft and after sternal closure. Blood glucose was measured at the same time. RESULTS: There was no significant difference in cardiac enzymes, hemodynamic parameters and blood glucose between the two groups. The use of vasoactive, inotropic and/or anti-arrhythmic agents, insulin and supplemental glucose was not significantly different between the groups. CONCLUSION: The results suggest that the intravenous administration of GIK during OP-CAB surgery neither reduces myocardial damage nor improves intra-operative cardiac performance in patients without contractile dysfunction.

Topical lidocaine effectively reduced the increase of systolic blood pressure after side-clamping of the aorta in off-pump cardiac surgery.

BACKGROUND: Side-clamping of the ascending aorta during off-pump coronary artery bypass surgery (OPCAB) may be associated with a significant increase in systemic blood pressure which may rarely result in aortic dissection. We evaluated whether topical application of lidocaine on the ascending aorta could reduce the rise in systemic blood pressure during side-clamping of the aorta in OPCAB. METHODS: Forty-four patients scheduled for OPCAB were randomly allocated to receive gauze soaked with 10 ml of 4% lidocaine (n = 22) or normal saline (n = 22) on the side-clamping site of the aorta. Sodium nitroprusside (SNP) was infused as necessary to maintain the systolic blood pressure at around 100 mmHg immediately prior to and during side-clamp of the aorta. The requirement and frequency of use of SNP, as well as haemodynamic variables, were recorded serially. RESULTS: The number of patients requiring an SNP infusion and the average amount of infused SNP were significantly less in the lidocaine group. Systolic blood pressure increased significantly during side-clamping in the control group, but not in the lidocaine group. CONCLUSION: Topical application of lidocaine on the surface of the aorta is a simple and effective method to reduce the risk of a sudden increase in systemic blood pressure during side-clamping of the aorta.