Summary

Background and objective: The use of inhalation sedation with sub-anaesthetic concentrations of sevoflurane and nitrous oxide mixture is expected to reduce amounts of intravenous sedative drugs needed to produce a balanced sedation with the benefits of having reduced side-effects. Methods: Eighty-two patients requiring endoscopic and/or surgical procedures under conscious sedation and local anaesthesia were recruited for this pilot study. Conscious sedation was induced with a titrated dose of midazolam and propofol given intravenously until the clinical end-point of conscious sedation was achieved. Subsequently, during the procedure, the patient was asked to breathe sevoflurane 0.1–0.3% and a fixed ratio of 40% nitrous oxide in oxygen given through a face mask. Results: In 78 patients (95.1%), the treatment was completed successfully. Patients were discharged back to the wards within 4–16 min (10.1) without significant side-effects. Treatment was satisfactorily accepted by 38 patients (48.7%) and considered excellent by 40 patients (51.3%). Conclusions: The use of titrated doses of intravenous sedative drugs for induction of conscious sedation followed by the use of low concentrations (0.1–0.3%) of sevoflurane combined with 40% nitrous oxide for maintenance of conscious sedation in patients requiring endoscopic and/or surgical procedures under local anaesthesia, has the potential advantages of reducing amounts of intravenous sedative drugs, less likelihood of problems from drug side-effects and fast recovery and discharge time. Further investigations to establish the technique are currently in progress.

Summary

Objective: To evaluate the effect of postoperative pain control in cardiac surgical patients on morbidity, mortality and other outcome measures. Background: New approaches in pain control have been introduced over the past decade. The impact of these interventions, either alone or in combination, on perioperative outcome was evaluated in cardiac surgical patients. Methods: We searched Medline for the period of 1980 to the present using the key terms analgesics, opioid, non-steroidal anti-inflammatory drugs, cardiac surgery, regional analgesia, spinal, epidural, fast-track cardiac anaesthesia, fast-track cardiac surgery, myocardial ischaemia, myocardial infarction, postoperative care, accelerated care programmes, postoperative complications, and we examined and discussed the articles that were identified to be included in this review. Results: Pain management in cardiac surgery is becoming more important with the establishment of minimally invasive direct coronary artery bypass surgery and fast-track management of conventional cardiac surgery patients. Advances have been made in this area and encompass specific techniques, such as central neuraxial blockade or selective nerve blocks, and drugs (opioids, sedative-hypnotics and non-steroidal anti-inflammatory drugs). Ideally, these therapies provide not only patient comfort but also mitigate untoward cardiovascular responses, pulmonary responses, and other inflammatory and secondary sympathetic responses. The introduction of these newer approaches to perioperative care has reduced morbidity, but not mortality, in cardiac surgical patients. Conclusions: Understanding perioperative pathophysiology and implementation of care regimes to reduce the stress of cardiac surgery, will continue to accelerate rehabilitation associated with decreased hospitalization and increased satisfaction and safety after discharge. Reorganization of the perioperative team (anaesthesiologists, surgeons, nurses and physical therapists) will be essential to achieve successful fast-track cardiac surgical programmes. Developments and improvements of multimodal interventions within the context of ‘fast-track’ cardiac surgery programmes represents the major challenge for the medical professionals working to achieve a ‘pain and risk free’ perioperative course.

Background and objective: A new posterior approach to the sciatic nerve in the subgluteal region was developed. We describe our clinical experiences on 135 consecutive patients.

Methods: All blocks were performed with a nerve stimulator (stimulation frequency 2 Hz; intensity from 1 reduced to ≤0.5 mA before application). A line was drawn from the greater trochanter to the ischial tuberosity of the femur; then, from the mid-point of this line, a second line was drawn perpendicularly and extended caudally for 4 cm: the end of this line represented the entry point of the needle. Sciatic stimulation was elicited at ≤0.5 mA; then ropivacaine 0.75% 20 mL was injected. An independent observer recorded the time from needle insertion to successful sciatic nerve stimulation (performance time), the depth of appropriate sciatic stimulation and the number of needle redirections, as well as the quality of nerve block, the discomfort during the procedure and patient acceptance.

Results: The performance time was 41 ± 25 s (mean ± SD) and the mean (SD) depth at which the sciatic nerve stimulation was found was 45 ± 10 mm. The median (range) number of needle redirections required to find the proper sciatic stimulation was 2 (1–5). The tibial response was observed in 77 patients (57%), while the common peroneal response was observed in 58 patients (43%). The degree of discomfort reported was very low and only 16 patients (12%) reported severe pain during placement of the block. The onset time (mean ± SD) of sensory and motor block was 7 ± 4 and 17 ± 13 min respectively, and the surgical procedure was completed with only the peripheral nerve block in 127 patients (94%). The same anaesthesia procedure was acceptable by 127 patients (94%) and only eight patients (6%) would prefer a different anaesthesia technique in the future.

Conclusions: The study demonstrated that the sciatic nerve can be easily blocked using this new posterior subgluteal approach, suggesting that it represents a safe and effective alternative to block the sciatic nerve at a proximal level, with the potential for reducing the discomfort experienced by the patient during block placement.

Background and objective: To investigate the interactions of postoperative pain and endocrine stress response, three groups of 21 patients each with total knee arthroplasty were compared in a randomized, prospective design. For postoperative pain management, a three-in-one block, an epidural catheter analgesia or an intravenous patient-controlled analgesia was used.

Methods: After standardized balanced anaesthesia, the pain intensity was measured by a visual analogue scale (VAS). For detection of epinephrine, norepinephrine, antidiuretic hormone, adrenocorticotropic hormone and cortisol in the plasma, blood samples were taken at six time points before and up to 180 min after the start of pain therapy. In addition, systolic arterial pressure, heart rate, partial arterial oxygen saturation, nausea, vomiting and satisfaction of the patients were recorded.

Results: Within 15 min after the start of pain therapy, VAS in all groups was similarly reduced from >40 mm to a range <10 mm (P < 0.001). Initially, all endocrine stress variables exceeded the normal range. Epidural anaesthesia led to a significant decrease of epinephrine and norepinephrine concentrations, while an increase was observed in the group with patient-controlled analgesia, and the decrease in patients with the three-in-one block was less than in patients receiving epidural anaesthesia (P = 0.001). Differences in antidiuretic hormone, adrenocorticotropic hormone and cortisol were less pronounced. Systolic arterial pressure decreased significantly in all groups, particularly in patients with epidural anaesthesia. Partial arterial oxygen saturation and the incidence of nausea and vomiting were comparable. All patients were satisfied with the methods used.

Conclusions: All methods of pain management led to sufficient analgesia, but they were not accompanied by an adequate reduction in endocrine stress response. Thus, postoperative pain is only a secondary stressor and sufficient analgesia with subjective well-being does not prove a stress-free state. With regard to the reduction of sympathoadrenergic stress response, epidural anaesthesia is superior to the three-in-one block and patientcontrolled analgesia. Epidural anaesthesia is recommended particularly for high-risk patients with hypertension, coronary heart disease and diabetes mellitus. In these patients, the reduction of a ‘hidden’ endocrine stress response in addition to prevention of pain is of special interest.

Background and objective: Although combined spinal and epidural anaesthesia is efficient and easy to perform, the technique can be a double-edged sword having the potential risk that an increased flux of drugs across the meninges through the hole made in it may lead to severe adverse effects. The aim was to compare the incidence of adverse events when an epidural injection of morphine was given after combined spinal and epidural anaesthesia or after epidural anaesthesia.

Methods: Fifteen patients had an epidural catheter inserted at the L2–3 interspace, and then a spinal block administered via the L3–4 interspace. Another 15 patients only had an epidural catheter inserted. After the onset of spinal or epidural anaesthesia had been confirmed, morphine 2 mg was injected into the epidural space, and a continuous epidural infusion of morphine was started. At the end of the operation and at 4, 8 and 12 h after the administration of epidural morphine and on the next day, the following variables were examined: blood pressure, heart rate, respiratory rate, arterial blood-gas analysis, visual analogue scale pain scores, nausea/ vomiting scores, and pruritus scores.

Results: In the study population, the epidural injection of morphine was not associated with a significantly higher incidence of adverse events when given after spinal anaesthesia than after epidural anaesthesia.

Conclusions: The adverse effects associated with epidural morphine given after spinal anaesthesia did not increase significantly when a 27-G Whitacre needle was used. Thus, the morphine flux through the meningeal hole into the cerebrospinal fluid was trivial.

Background and objective: Clinical studies suggest that lidocaine may induce irreversible neurological damage after spinal application in human beings. The mechanisms underlying the possible cytotoxic action of lidocaine have only been suggested from animal studies. This study aimed to investigate if lidocaine exhibited cytotoxic action in a human model widely used for the study of neuronal apoptosis. This is important to know as it may help one to judge on possible neurotoxic risks imposed by the spinal application of lidocaine.

Methods: The concentration- and time-dependent effects of lidocaine on retinoic acid-differentiated human neuroblastoma SH-SY5Y cells were quantified by trypan blue staining, the release of lactate dehydrogenase, immunocytochemistry and flow cytometry.

Results: The local anaesthetic caused a significant increase in the number of cells staining positive for trypan blue, a significant increase of LDH release into the incubation medium, and a significant increase of 7AAD and annexin V binding. Lidocaine induced apoptosis already at 3 mm. At a concentration of 10 mmol 47% of the cells and at 30 mmol 98% of the cell population was necrotic. Both necrosis and apoptosis were time-dependent.

Conclusions: The results demonstrate that lidocaine exhibited neurotoxic effects in a human model established for the study of drug-induced neuronal apoptosis. The results were consistent with the neurotoxic clinical effects of lidocaine. These effects may be produced by more than a single mechanism.

Background and objective: The α2-adrenoceptor agonist clonidine has potent central antinociceptive properties. The study was designed to investigate the effects of the combined subarachnoid administration of clonidine and prilocaine on spinal block and postoperative analgesia for the transurethral resection of tumours in the urinary bladder.

Methods: The controlled, prospective, double-blind study enrolled 40 patients scheduled for elective transurethral resection of bladder tumours under spinal anaesthesia with prilocaine. Patients were randomly assigned to receive an intrathecal injection of prilocaine 75 mg alone (control group) or in combination with clonidine 75 µg. We assessed haemodynamic changes (non-invasive arterial pressure, heart rate), pulse oximetry, the upper level of block, the onset and duration of sensory and motor block, postoperative analgesia and any adverse effects.

Results: There were no statistically significant differences in demographic data, heart rate, onset time or the levels of sensory or motor block. Analgesia lasted significantly longer in the clonidine group (498.4 ± 226.9 versus 187.2 ± 103.1 min; P < 0.05). The duration of motor block was longer in the clonidine group (165.5 ± 30.6 min) than in the control group (139.7 ± 40.4 min; P < 0.05) and the duration of sensory block was also longer in the clonidine group (157.3 ± 24.5 min) than in the control group (137.2 ± 31.2 min; P < 0.05). Fewer patients in the recovery room needed metamizol (dipyrone) in the clonidine group (5%) than in the control group (50%). Arterial pressure decreased significantly in the clonidine group 75-135 min after the block.

Conclusions: The addition of clonidine 75 µg to prilocaine 75 mg for subarachnoid anaesthesia increased the duration of sensory and motor block and reduced the need for additional postoperative analgesics by providing excellent analgesia for about 8 h during recovery from transurethral resection of bladder tumours.

Background and objective: The epidural and subarachnoid spaces should be identified at the first attempt, since multiple punctures increase the risk of postdural puncture headache, epidural haematoma and neural trauma. The study aimed to describe the predictors of successful neuraxial blocks at the first attempt.

Methods: After institutional Review Board approval, 1481 patients undergoing spinal or epidural anaesthesia were prospectively enrolled. For each block we recorded: gender, age, height, weight, body habitus, anatomical landmarks (palpability of the spinous processes), spinal anatomy, patient positioning, premedication, needle type and gauge, approach, spinal level of the block, and the provider’s level of experience. Retrieval of cerebrospinal fluid or loss of resistance to saline or air identified the subarachnoid and epidural spaces, respectively. The outcome variable was the first attempt success or failure (whether or not the needle was correctly located with one skin puncture and produced adequate surgical anaesthesia). Backward stepwise logistic regression tested its association with the other variables.

Results: The first-attempt rate of success was 61.51%. Independent predictors (Odds ratio, 95% confidence limits) were the quality of anatomical landmarks (1.92 (1.57; 2.35)), the provider’s level of experience (1.24 (1.15; 1.33)) and the adequacy of patient positioning (3.84 (2.84; 5.19)).

Conclusions: The successful location of the subarachnoid or the epidural space at the first attempt is influenced by the quality of patients’ anatomical landmarks, the adequacy of patient positioning and the provider’s level of experience.

Background and objective Little information exists on cerebrospinal fluid pressures in non-labouring pregnant women. The technique of spinal anaesthesia means that inadequate levels of sensory blockade are difficult to manage. If the block is found to be inadequate after surgery has commenced, then conversion to general anaesthesia may be the only option. It is important that any manoeuvre altering the spread of local anaesthetic is considered at the time of subarachnoid injection. This study investigates the feasibility of using a fine bore needle with an electronic transducer to measure cerebrospinal fluid pressure and whether this was affected by either of the two lateral positions. We also sought to measure whether the right or left lateral position affected subsequent block height and requirements for supplementary analgesia.

Methods Two groups of 17 women presenting for elective Caesarean section were allocated to receive spinal anaesthesia in either the right or left lateral position. Cerebrospinal fluid pressure was measured by use of a rapid response electronic transducer connected to the hub of the spinal needle. Anaesthetic levels to cold sensation were assessed at 5, 10 and 15 min after injection of hyperbaric bupivacaine. During surgery, requirements for supplementary analgesia were recorded.

Results There was no significant difference in cerebrospinal fluid pressure between the two positions. While there was a trend towards more rapid analgesia in the right lateral group, this did not reach statistical significance. Two blocks performed in the left lateral group were inadequate for surgery but this was not statistically significant. Overall, 39% of women required supplementary analgesia during surgery. The incidence was not significantly different between the two groups.

Conclusion Adoption of either the right or left lateral position for placement of spinal anaesthesia results in no difference in cerebrospinal fluid pressure or quality of block. The technique described gives a reliable and reproducible method of cerebrospinal fluid pressure measurement.

Background and objective The effect of anaesthesia induced by intrathecal injection of 6.3% MgS04 or 4% lidocaine on intracellular electrolyte homeostasis in spinal cord neurones of a rat model was investigated. Methods Intracellular Ca2+, Mg2+, Na+ and K+ concentrations were determined at different times after intrathecal administration of NaCI (saline, a control group), MgS04 or lidocaine.

Results In both thoracic and lumbar spinal cord segments, Ca2+ concentrations rose significantly 30min and 2 h after 6.3% MgSO4 injection, and after 24 h were still significantly increased compared with the values obtained from the control group which were subjected to sham ‘anaesthesia’ by saline injection (172,121 and 108ngmg−1 protein vs. control 23ngmg−1 protein, respectively, in the thoracic segment and 222, 229 and 176ngmg−1 protein vs. control 43ngmg−1 protein, respectively, in the lumbar segment). Lidocaine injection also produced a significant increase in intracellular Ca2+ in the thoracic and lumbar spinal cord segments (69, 64 and 53ngmg−1 protein vs. control 33.4 ngmg−1 protein and 26, 94 and 46ngmg−1 protein vs. 23ngmg−1 protein respectively). Only a modest rise in intracellular Mg2+ was observed after intrathecal MgS04 or lidocaine injection (27ngmg−1 protein vs. 23ngmg−1 protein). Na+ and K+ concentrations decreased 24 h after MgS04and 1h after lidocaine injection.

Conclusion Intrathecal anaesthesia by MgS04 or lidocaine alters intracellular electrolyte homeostasis in spinal cord neurones of experimental rats. A possible common mechanism of action via Ca2+ ion channels is discussed.