Image quality of CT angiography in young children with congenital heart disease: a comparison between the sinogram-affirmed iterative reconstruction (SAFIRE) and advanced modelled iterative reconstruction (ADMIRE) algorithms.

AIM: To compare the image quality of computed tomography angiography (CTA) reconstructed by sinogram-affirmed iterative reconstruction (SAFIRE) with that of advanced modelled iterative reconstruction (ADMIRE) in children with congenital heart disease (CHD). MATERIAL AND METHODS: Thirty-one children (8.23±13.92 months) with CHD who underwent CTA were enrolled. Images were reconstructed using SAFIRE (strength 5) and ADMIRE (strength 5). Objective image qualities (attenuation, noise) were measured in the great vessels and heart chambers. Two radiologists independently calculated the contrast-to-noise ratio (CNR) by measuring the intensity and noise of the myocardial walls. Subjective noise, diagnostic confidence, and sharpness at the level prior to the first branch of the main pulmonary artery were also graded by the two radiologists independently. RESULTS: The objective image noise of ADMIRE was significantly lower than that of SAFIRE in the right atrium, right ventricle, and myocardial wall (p<0.05); however, there were no significant differences observed in the attenuations among the four chambers and great vessels, except in the pulmonary arteries (p>0.05). The mean CNR values were 21.56±10.80 for ADMIRE and 18.21±6.98 for SAFIRE, which were significantly different (p<0.05). In addition, the diagnostic confidence of ADMIRE was significantly lower than that of SAFIRE (p<0.05), while the subjective image noise and sharpness of ADMIRE were not significantly different (p>0.05). CONCLUSION: CTA using ADMIRE was superior to SAFIRE when comparing the objective and subjective image quality in children with CHD.

Effect-site concentration of remifentanil for laryngeal mask airway insertion during target-controlled infusion of propofol.

The purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 microg.ml(-1) without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted. The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC(50)) was 3.04 (SD 0.49) ng.ml(-1) during a TCI of 3.5 microg.ml(-1) propofol without neuromuscular blockade. From the probit analysis, the EC(50) and EC(95) of remifentanil were 2.84 ng.ml(-1) (95% CI 2.09-3.57 ng.ml(-1)) and 3.79 ng.ml(-1) (95% CI 3.26-9.25 ng.ml(-1)), respectively.

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.

A randomised, crossover comparison between the CobraPLA and the LMA Classic in paralysed patients.

We performed a randomised, crossover study in 38 anaesthetised and paralysed patients to compare the performance of the CobraPLA and the LMA Classic during controlled ventilation. The median (IQR [range]) airway leak pressure was 23.0 (20-24 [12-30]) cmH(2)O for the CobraPLA and 15.0 (12-19 [8-30]) cmH(2)O for the LMA Classic (p < 0.001). The median (IQR [range]) insertion time was 15.0 (11-26 [9-31]) s for the CobraPLA and 22.5 (20-25 [15-50]) s for the LMA Classic (p < 0.001). There was no significant difference between the two devices for the number of insertion and reposition attempts, the anatomical position scored by fibreoptic bronchoscopy or the peak and plateau airway pressures. There were no adverse events during anaesthesia. The CobraPLA provides a better airway leak pressure and takes less time to insert than the LMA Classic in paralysed patients. Our data show that the CobraPLA can be used to secure a patent airway during controlled ventilation in selected patients.

Epidural naloxone reduces postoperative nausea and vomiting in patients receiving epidural sufentanil for postoperative analgesia.

BACKGROUND: Epidural opioids have excellent analgesic properties, but their side-effects limit their use in patient-controlled epidural analgesia. This study was designed to evaluate the effect of epidural naloxone on the side-effects of sufentanil, focusing on postoperative nausea and vomiting (PONV) in patients undergoing total knee replacement (TKR). METHODS: After obtaining Institutional Review Board approval and informed consent, 50 patients undergoing unilateral TKR were randomly assigned to receive either sufentanil in ropivacaine alone (Group C, n = 25) or the same solution with naloxone (Group N, n = 25) for their postoperative epidural analgesia. Episodes of PONV and five-point-scaled nausea scores were evaluated at 6, 12, and 24 h after epidural analgesia was started. Visual analogue scale (VAS) score for pain and the incidence of sedation, pruritus, hypotension, and respiratory depression were also evaluated at each of three time points. RESULTS: The nausea score in Group N was significantly lower than that in Group C. The VAS pain score at rest and on movement were significantly lower in Group N than in Group C at 24 h. Other opioid-induced side-effects were not significantly different. CONCLUSIONS: Epidural naloxone was effective in reducing PONV induced by epidural sufentanil and additionally enhanced the analgesic effect. Therefore, concomitant infusion of a small dose of epidural naloxone should be considered to reduce PONV, especially in patients at greater risk for PONV.

Effects of chronic angiotensin II receptor antagonist and angiotensin-converting enzyme inhibitor treatments on neurohormonal levels and haemodynamics during cardiopulmonary bypass.

BACKGROUND: Chronic treatment with renin-angiotensin system (RAS) antagonists frequently causes deleterious hypotension during anaesthesia. We compared the effects of angiotensin II receptor antagonists (ARA) and angiotensin-converting enzyme inhibitors (ACEI) on neurohormonal levels and haemodynamics during cardiopulmonary bypass (CPB). METHODS: Forty-four patients undergoing mitral valvular surgery who were treated with either ARA (ARA group, n=14) or ACEI (ACEI group, n=15) over 12 weeks or who were not treated with any RAS antagonist (control group, n=15) were enrolled. The plasma levels of epinephrine, norepinephrine, arginine vasopressin (AVP) and angiotensin II, and haemodynamic variables were measured before (T1) and 15 min after (T2) the start of CPB, before aortic unclamping (T3) and at skin closure (T4). Mean arterial pressure (MAP) was maintained above 60 mm Hg with phenylephrine administration during CPB. RESULTS: The plasma epinephrine, norepinephrine, AVP and angiotensin II levels increased during CPB in all groups. Compared with the control group, the AVP level was lower at T1 in the ARA group and at T2 in the ARA and ACEI groups. The angiotensin II level was higher at T1, T2 and T3 in ARA group compared with ACEI and control groups. There were no significant differences in the epinephrine and norepinephrine levels among the three groups. The amount of administered phenylephrine during CPB was greater and MAP was lower in the ARA group compared with the ACEI and control groups. CONCLUSIONS: Chronic ARA treatment resulted in more profound hypotension than ACEI treatment during CPB, and this may be associated with the blockade of angiotensin II receptors by ARA.

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.

Effect of pre-operative angiotensin-converting enzyme inhibitors on haemodynamic parameters and vasoconstrictor requirements in patients undergoing off-pump coronary artery bypass surgery.

The effects of pre-operative angiotensin-converting enzyme inhibitor (ACEI) treatment on haemodynamic status and vasoconstrictor requirements during off-pump coronary artery bypass surgery (OPCAB) were studied. Eighty patients selected for OPCAB were divided into those who had been treated with ACEIs for 4 weeks or more pre-operatively (ACEI group) (n = 43) and those who had not been treated with ACEIs (control group) (n = 37). Noradrenaline was infused during the operation when the mean systemic arterial pressure (SAP) fell below 60 mmHg. No significant differences in the haemodynamic parameters measured were detected between the two groups, except for cardiac output, which was found to be significantly greater in the control group. During anastomosis of the obtuse marginal branch of the left circumflex artery (OM), a significantly larger amount of noradrenaline was required by the ACEI group compared with the control group. In conclusion, pre-operative treatment with ACEIs significantly increased the amount of vasoconstrictor necessary to maintain the target SAP during OM anastomosis during OPCAB.

Relationship between arterial and end-tidal carbon dioxide pressures during anesthesia using a laryngeal tube.

BACKGROUND: The Laryngeal Tube (LT), (VBM Medizintechnik, Sulz, Germany) is a relatively new supraglottic device for controlling the airway. Arterial carbon dioxide tension (PaCO(2)) can be estimated by monitoring the end-tidal tension of carbon dioxide (PETCO(2)). The relationship between PETCO(2) and PaCO(2) during controlled ventilation via the LT has not been reported. METHODS: During general anesthesia, 45 patients were mechanically ventilated using an LT. PETCO(2) and PaCO(2) were measured once PETCO(2) had reached a steady state. The LT was then removed and the trachea intubated using an endotracheal tube (ETT), and the identical ventilatory variables were resumed. Following stabilization, PETCO(2) was again determined and PaCO(2) estimated. RESULTS: The mean PETCO(2) and PaCO(2) values were 4.43 +/- 0.26 kPa and 4.67 +/- 0.32 kPa, respectively, during LT ventilation, and 4.36 +/- 0.23 kPa and 4.61 +/- 0.26 kPa, respectively, during ETT ventilation. Analysis of differences between the PETCO(2) and PaCO(2) values using the Bland and Altman method revealed a bias +/- precision of 0.24 +/- 0.15 kPa for LT and 0.27 +/- 0.15 kPa for ETT. The root mean square error was 0.28 for the LT and 0.30 for the ETT. CONCLUSION: This study suggests that for healthy adult patients mechanically ventilated via the LT, the PETCO(2) value reflects the PaCO(2) value as closely as when patients are ETT ventilated, allowing capnometry to be used to evaluate the adequacy of ventilation.