Summary

Background and objective: The effects of intra-aortic balloon pumping (IABP) on cerebral perfusion are still a matter of debate. End-diastolic reversal of blood flow in cerebral arteries has been observed in a small number of patients. We prospectively investigated the incidence and the amount of transient cerebral artery blood flow reversal during balloon pumping in patients recovering from cardiac surgery.

Methods: In 23 patients receiving IABP support, blood flow velocities in the right middle cerebral artery were assessed by transcranial Doppler-sonography. Additionally, systemic haemodynamics were monitored. In each patient, measurements were performed at three different pump settings: without support, assist ratio 1 : 1 and assist ratio 1 : 2.

Results: In 8 of 23 patients, balloon pumping caused a transient diastolic reversal of blood flow in the middle cerebral artery during balloon deflation. Antegrade mean flow velocity in the middle cerebral artery significantly increased from 57 ± 27 to 61 ± 26 (assist ratio 1 : 1) and 61 ± 29 cm s−1 (assist ratio 1 : 2) (P < 0.05). Taking transient blood flow reversal into account, net mean flow velocity did not increase with balloon pump support. Systemic haemodynamic parameters remained unchanged.

Conclusion: Left ventricular support with IABP significantly changed flow patterns in basal cerebral arteries of our patients. In 35% of patients, support resulted in a transient reversal of intracranial blood flow which counterbalanced a slight increase in mean antegrade flow.

Summary

Chronic pain represents a major public health problem that impacts negatively on quality-of-life issues and healthcare costs. Unrelieved acute post-traumatic and postoperative pains are risk factors in the development of chronic pain, although psychological and environmental factors are at work as well. Flagging pain (blue, yellow and red flags) helps to identify risk factors in acute pain that need attention to avoid the transition from acute postoperative pain to acute persistent and then on to chronic pain. This offers a unique opportunity for preventative medicine.

Summary

A variety of laboratory and clinical studies clearly indicate that exposure to anaesthetic agents can lead to a pronounced protection of the myocardium against ischaemia–reperfusion injury. Several changes in the protein structure of the myocardium that may mediate this cardioprotection have been identified. Ischaemia–reperfusion of the heart occurs in a variety of clinical situations including transplantations, coronary artery bypass grafting or vascular surgery. Ischaemia may also occur during a stressful anaesthetic induction. Early restoration of arterial blood flow and measures to improve the ischaemic tolerance of the tissue are the main therapeutic options (i.e. cardioplegia and betablockers). There exists increasing evidence that anaesthetic agents interact with the mechanisms of ischaemia–reperfusion injury and protect the myocardium by a ‘preconditioning’ and a ‘postconditioning’ mechanism. Hence, the anaesthesiologist may substantially influence the critical situation of ischaemia–reperfusion during surgery by choosing the appropriate anaesthetic agent. This review summarizes the current understanding of the mechanisms of anaesthetic-induced myocardial protection. In this context, three time windows of anaesthetic-induced cardioprotection are discussed: administration (1) during ischaemia, (2) after ischaemia–during reperfusion (postconditioning) and (3) before ischaemia (preconditioning). Possible clinical implications of these interventions will be reviewed.

Summary

Background and objective: For the treatment of patients with adult respiratory distress syndrome and acute lung injury bedside measurements of regional lung ventilation should be considered for optimizing ventilatory settings. The aim was to investigate the effect of positive end-expiratory pressure (PEEP) on regional ventilation in mechanically ventilated patients at the bedside by electrical impedance tomography. Methods: Eight mechanically ventilated patients were included in the study. PEEP levels were increased from 0 to 5, 10, 15 mbar and back to 0 mbar. Regional ventilation in 912 regions of the thorax was investigated at each PEEP by electrical impedance tomography. The obtained regions were divided in four groups: none (none and poorly ventilated regions including chest wall and mediastinum), bad, moderate and well-ventilated regions. Results: Increasing the PEEP stepwise from 0 to 15 mbar decreased the non-ventilated regions (none: 540 regions at PEEP 0 and 406 regions at PEEP 15). In contrast, the other regions increased (bad: 316 regions at PEEP 0 and 380 regions at PEEP 15; moderate: 40 regions at PEEP 0 and 100 regions at PEEP 15; well: 0 region at PEEP 0 and 34 regions at PEEP 15 (median values)) indicating an improvement of regional ventilation. Conclusions: Increasing PEEP in mechanically ventilated patients reduces none ventilated regions (atelectasis). Furthermore, it leads to a shift from none and bad ventilated regions to moderately and well-ventilated regions. Electrical impedance tomography is a bedside technique and might be an alternative to computed tomography scan to assess aerated lung regions.

Summary

The place of sub-Tenon's block in ophthalmic surgery is now established. This block was introduced into clinical practice in the early 1990s as a simple, safe and effective technique. Since then, techniques have evolved, newer cannulae have been introduced and many complications, both minor as well as major, have been reported. This review deals with the recent developments in sub-Tenon's block.

Summary

Background and objective: Levobupivacaine 0.5% and racemic bupivacaine 0.5% are equally effective in spinal anaesthesia. Fentanyl has been used as an adjunct to racemic bupivacaine in spinal anaesthesia. At the time this study was designed, there was no published study on the intrathecal use of 0.5% levobupivacaine with fentanyl. Methods: This prospective, randomized, double-blind study compared the clinical efficacy, motor block and haemodynamic effects of using 2.6 mL of 0.5% levobupivacaine alone (25 patients) and 2.3 mL of 0.5% levobupivacaine with fentanyl 15 μg in 0.3 mL (25 patients) for spinal anaesthesia in urological surgery. The study solution was injected into the subarachnoid space at the L3–L4 interspace. Results: There were no significant differences between the two groups in the haemodynamic changes, and quality of sensory and motor block. Anaesthesia was adequate and patient satisfaction was good in all cases. Side-effects were minor and infrequent with both regimes. Conclusions: We conclude that 2.3 mL of 0.5% levobupivacaine with fentanyl 15 μg is as effective as 2.6 mL of 0.5% levobupivacaine alone in spinal anaesthesia for urological surgery. Further studies may be directed to find the optimal combination of levobupivacaine and opioid with maximal haemodynamic stability and least motor block.

Summary

Background and objective: The aim of this study was to assess time dependent cumulative effects of three different inhalation anaesthetics on QTc interval during the maintenance of anaesthesia.

Method: Seventy-five ASA I–II male patients undergoing inguinal herniorrhaphy were randomly allocated into three groups. No premedication was given. Anaesthesia was induced with thiopental and tracheal intubation was facilitated by vecuronium in all groups. Anaesthesia was maintained with 0.8% halothane (Group I) (n = 25), 1% isoflurane (Group II) (n = 25), or 2% sevoflurane (Group III) (n = 25) and 66% nitrous oxide in oxygen. Three lead electrocardiogram recordings were taken before induction, 2, 5, 10, 15, 30 and 45 min after induction and after extubation. Heart rate, systolic, diastolic, mean arterial pressure and SPO2 were recorded at the same time. Heart rate and corrected QT interval were evaluated by using Bazett's formula. Multivariate analysis of variance for repeated measures was used to determine intergroup and intragroup differences.

Results: There was no statistically significant difference in the baseline QTc values of the groups. There was no difference between QTc values with halothane and sevoflurane. There was a difference between QTc values with isoflurane and those with the other two inhalation anaesthetics (P < 0.05). Although QTc values in the isoflurane group were higher at all times, the critical value of 440 ms was not exceeded.

Conclusion: We conclude that halothane 0.8%, isoflurane 1% and sevoflurane 2% do not prolong QTc interval.

Summary

Electromagnetic interference produced by wireless communication can affect medical devices and hospital policies exist to address this risk. During the transfer of ventilated patients, these policies may be compromised by essential communication between base and receiving hospitals. Local wireless networks (e.g. Bluetooth®) may reduce the ‘spaghetti syndrome’ of wires and cables seen on intensive care units, but also generate electromagnetic interference. The aim of this study was to investigate these effects on displayed and actual ventilator performance. Methods: Five ventilators were tested: Drager Oxylog 2000, BREAS LTV-1000, Respironics BiPAP VISION, Puritan Bennett 7200 and 840. Electromagnetic interference was generated by three devices: Simoco 8020 radio handset, Nokia 7210 and Nokia 6230 mobile phone, Nokia 6230 communicating via Bluetooth with a Palm Tungsten T Personal Digital Assistant. We followed the American National Standard Recommended Practice for On-Site, Ad Hoc Testing (ANSI C63) for electromagnetic interference. We used a ventilator tester, to simulate healthy adult lungs and measure ventilator performance. The communication device under test was moved in towards each ventilator from a distance of 1 m in six axes. Alarms or error codes on the ventilator were recorded, as was ventilator performance. Results: All ventilators tested, except for the Respironics VISION, showed a display error when subjected to electromagnetic interference from the Nokia phones and Simoco radio. Ventilator performance was only affected by the radio which caused the Puritan Bennett 840 to stop functioning completely. The transfer ventilators' performance were not affected by radio or mobile phone, although the mobile phone did trigger a low-power alarm. Effects on intensive care ventilators included display reset, with the ventilator restoring normal display function within 2 s, and low-power/low-pressure alarms. Bluetooth transmission had no effect on the function of all the ventilators tested. Conclusion: In a clinical setting, high-power-output devices such as a two-way radio may cause significant interference in ventilator function. Medium-power-output devices such as mobile phones may cause minor alarm triggers. Low-power-output devices such as Bluetooth appear to cause no interference with ventilator function.

Summary

Background and objective: Preoperative epoetin alfa administration decreases transfusion requirements and may reduce transfusion complications, such as postoperative infection due to immune suppression and thus hospitalization time. This study examined the impact of preoperative epoetin alfa administration on postoperative recovery and infection rate.

Methods: In an open randomized controlled multicentre trial in patients undergoing orthopaedic surgery, the effects of preoperative administration of epoetin alfa vs. routine care were compared in six countries. Haemoglobin (Hb) values, transfusions, time to ambulation, time to discharge, infections and safety were evaluated in patients with preoperative Hb concentrations 10–13g dL−1 (on-treatment population: epoetin n = 460; control n = 235), from study entry until 4–6 weeks after surgery. Outcome was also compared in patients with and without transfusion.

Results: Epoetin-treated patients had higher Hb values from the day of surgery until discharge (P < 0.001) and lower transfusion rates (12% vs. 46%; P < 0.001). Epoetin treatment delivered no significant effect on postoperative recovery (time to ambulation, time to discharge and infection rate). However, the time to ambulation (3.8 ± 4.0 vs. 3.1 ± 2.2 days; P < 0.001) and the time to discharge (12.9 ± 6.4 vs. 10.2 ± 5.0 days; P < 0.001) was longer in the transfused than in the non-transfused patients. Side-effects in both groups were comparable.

Conclusions: Epoetin alfa increases perioperative Hb concentration in mild-to-moderately anaemic patients and thus reduces transfusion requirements. Patients receiving blood transfusions require a longer hospitalization than non-transfused patients.

Summary

Background and objective: The electroencephalographic Narcotrend Index (NI) is a measure of the hypnotic component of general anaesthesia. The purpose of this study was to evaluate the impact of Narcotrend guidance on propofol consumption and emergence times in children receiving total intravenous anaesthesia with propofol and remifentanil. Methods: Thirty children, aged 1–11 yr, scheduled for paediatric urological surgery were enrolled. Remifentanil was given to all patients at a constant infusion rate of 0.3 μg kg−1 min−1 throughout anaesthesia. Patients were randomly allocated to receive a continuous propofol infusion adjusted either according to a conventional clinical practice (Group C: n = 15) or guided by Narcotrend monitoring (Group NI: n = 15; target NI 60 ± 5). All patients were connected to the Narcotrend Monitor, but in Group C the anaesthetist was blinded to the screen of the monitor. Propofol consumption (mg kg−1 h−1) and emergence times (min) were the primary and secondary outcome measures. Results: Propofol consumption (median [inter-quartile range]) was significantly lower in Group NI compared to Group C (NI: 7.0 [6.4–8.2] vs. C: 9.3 [8.3–11.0] mg kg−1 h−1; P < 0.001), whereas Log-Rank-analysis revealed no intergroup difference in emergence times (Group NI: mean [95% confidence interval (CI)] 12.8 [11.2–14.4] min; Group C: 16.4 [12.6–20.2] min; P = 0.10). Haemodynamic variables remained stable within age-related limits, and there were no observations of adverse events, especially no clinical signs of intraoperative awareness in any patient. Conclusion: Narcotrend monitoring for guidance of propofol/remifentanil anaesthesia in children results in reduced propofol consumption compared to a conventional clinical practice.