Showing papers in "Acta Anaesthesiologica Scandinavica in 1998"

A risk score to predict the probability of postoperative vomiting in adults

Abstract: Background: The aim of this study was to identify factors most relevant for postoperative vomiting (PV) and to develop a risk score to predict the probability of PV. Methods: Adult inpatients scheduled for elective ear, nose and throat (ENT) surgery under general anaesthesia were offered to participate in a prospective study for PV over 24 h. No prophylactic antiemetics were used. The data of 1137 patients were randomized and split into an evaluation set (n=553) and a validation set (n=584). The evaluation set was subjected to logistic regression analysis to quantify the relative impact of anaesthetic, surgical and individual factors and to develop a risk score. The score was then tested by applying it to the validation set. The area under a receiver operation characteristic (ROC) curve was calculated and the predicted and actual incidences of patients were correlated. Results: In the evaluation set, patient-related factors (female gender, young age, non-smoking, history of PV or motion sickness) and a high duration of anaesthesia were independent risk factors for PV. The probability of PV could be estimated from the equation: PV=1/(1+exp(-z)) where z=1.28.(gender)-0.029 (age)-0.74 (smoking)+0.63 . (history of PV or motion sickness) +0.26 . (duration)-0.92. In the validation set this score achieved an area under the ROC-curve of 0.78 and the actual incidence correlated strongly with the predicted risks (R 2 =0.93, P<0.001). Conclusion: The data suggest that the probability of PV following ENT surgery under inhalational anaesthesia with low-dose opioids can be predicted by a score mainly based upon patient-related risk factors.

Epidural abscess complicating epidural anesthesia and analgesia: An analysis of the literature

Abstract: Background: Epidural abscess is a serious complication of epidural block. Because of its low incidence, the risk factors and the symptoms and cause of epidural abscess related to epidural anesthesia and analgesia are not well known by anesthesiologists. Methods: A computer-assisted search of the literature on epidural catheter-related abscess was performed to describe the clinical course and bacteriology of this complication, to determine possible risk factors, and to assess the index of suspicion among physicians. Results: Forty-two patients with a catheter-related epidural abscess were identified. Only in 15 patients was the correct diagnosis considered initially. The time from insertion of the epidural catheter to symptoms varied between 1 and 60 d. Initial symptoms included back pain, fever, and leukocytosis. The time from symptoms to treatment was a few hours to 108 d. Interval from first symptoms to treatment was significantly longer in patients with persistent neurologic deficits compared with patients who completely recovered. Staphylococcus aureus was the most common etiologic agent. Outcome was reported in 39 patients, but only 19 made a full recovery. Conclusion: The index of suspicion among anesthesiologists, other physicians and nurses taking care of patients with epidural catheters must be increased for this complication; this should shorten the interval from symptoms to treatment and lower the incidence of neurological sequelae.

Percutaneous dilatational tracheostomy versus conventional surgical tracheostomy. A clinical randomised study.

Abstract: Background: As no clinical randomised studies have previously been performed comparing complications with the Ciaglia Percutaneous Dilatational Tracheostomy Introducer Set (PDT) and conventional surgical tracheostomy (TR), we designed a study with the aim of comparing the efficacy and safety of the two techniques. Methods: Sixty patients selected for elective tracheostomy were randomised for either PDT (30 patients) or TR (30 patients). All patients had general anaesthesia and were ventilated with 100% oxygen. Furthermore, lidocaine with epinephrine 1% (3-5 ml) was used for local analgesia and to minimise bleeding during the procedure. Results: The median time for insertion of the tracheostomy tube was 11.5 min (range 7-24 min) in the PDT group and 15 min (range 5-47 min) in the TR group (P<0.01). Complications during the procedure were cuff puncture of the endotracheal tube in 5 cases in the PDT group. Minor bleeding was encountered in 6 cases in the PDT group as opposed to 24 cases in the TR group (P<0.01), major bleeding in none versus 2 cases, respectively. In 8 cases in the PDT group, increased resistance to insertion of the tracheostomy tube was met by further dilatation. During the post-tracheostomy period, complications occurred with minor bleeding in 2 cases in the PDT group as opposed to 9 cases in the TR group (P<0.05), and major bleeding was encountered in 1 case in each group. Minor infections were encountered in 3 cases in the PDT group as opposed to 11 cases in the TR group (P<0.01). Major infection was encountered in none versus 8 cases, respectively (P<0.01). Conclusion: Our results indicate that the percutaneous dilatational tracheostomy technique performed with the Ciaglia Introducer Set is effective, safe and superior to conventional surgical tracheostomy as immediate complications as well as complications with the tracheostomy tube in situ are fewer and of less severity.

Efficacy of propacetamol in the treatment of postoperative pain Morphine-sparing effect in orthopedic surgery

Abstract: Background: Combined analgesic regimens have been suggested to improve the treatment of postoperative pain. The aim of our study was to evaluate the analgesic efficacy and tolerability of propacetamol, in combination with morphine. Methods: Four i.v. infusions of propacetamol 2 g or placebo were administered, in a double-blind fashion, after orthopedic surgery (n=97). Morphine was administered by a patient-controlled analgesia (PCA) device. The total dose of morphine, pain intensity and global efficacy of treatment were evaluated. Tolerability was assessed by monitoring blood pressure, heart and respiratory rate, sedation scores, adverse events, and renal and hepatic parameters. Results: The total dose of morphine was significantly decreased in the propacetamol group compared to placebo (9.4±8.5 mg vs 17.6±12 mg; P< 0.001), arriving at a sparing effect of 46%. The evolution of pain intensity showed a similar pattern in the two groups. Global efficacy of treatment was rated significantly better by patients receiving the combination propacetamol+ PCA morphine (87% of “good”/“excellent” ratings vs 65%; P=0.01). Tolerability was comparable in the two groups. Eight patients in the propacetamol and 4 patients in the placebo group reported adverse events, of mild/moderate intensity, most commonly nausea/vomiting. Renal and hepatic parameters were also seen to be comparable. Conclusions: These results confirm a significant morphine-sparing effect, significantly better scores in the final assessment by patients, and a good tolerability of propacetamol after orthopedic surgery. The drug may, therefore, represent a useful alternative to NSAIDs, as complementary drug to opioids, in the management of moderate/severe postoperative pain.

Comparing analgesic efficacy of non‐steroidal anti‐inflammatory drugs given by different routes in acute and chronic pain: A qualitative systematic review

Abstract: Aim: To test the evidence for a difference in analgesic efficacy and adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs) given by different routes. Methods: Systematic review of published randomised controlled trials. Relevant trials were comparisons of the same drug given by different routes. Presence of internal sensitivity was sought as a validity criterion. Analgesic and adverse effect outcomes were summarised, and synthesised qualitatively. Results: In 26 trials (2225 analysed patients), 8 different NSAIDs were tested in 58 comparisons. Fifteen trials (58%) compared the same drug by different routes. Drugs were given by intravenous, intramuscular, intrawound, rectal and oral routes in postoperative pain (14 trials), renal colic (4), acute musculo-skeletal pain (1), dysmenorrhoea (1), and rheumatoid arthritis (6). Five of the 15 direct comparisons were invalid because they reported no difference between routes but without evidence of internal sensitivity. In all 3 direct comparisons in renal colic, intravenous NSAID had a faster onset of action than intramuscular or rectal. In 1 direct comparison in dysmenorrhoea, oral NSAID was better than rectal. In the 5 direct comparisons in postoperative pain, results were inconsistent. In 1 direct comparison in rheumatoid arthritis, intramuscular NSAID was better than oral. Injected and rectal administration had some specific adverse effects. Conclusion: In renal colic there is evidence that NSAIDs act quickest when given intravenously. This may be clinically relevant. In all other pain conditions there is a lack of evidence of any difference between routes. In pain conditions other than renal colic, there is, therefore, a strong argument to give oral NSAIDs when patients can swallow.

Comparison of analgesic efficacy of oxycodone and morphine in postoperative intravenous patient-controlled analgesia.

Abstract: Background: Morphine has been the standard opioid in patient-controlled analgesia (PCA). Oxycodone, the analgesic potency of which in i.v. administration has been suggested to be slightly greater than that of morphine, has not yet been studied for its efficacy in PCA. Methods: Fifty patients, undergoing a plastic reconstruction of the breast or a major operation of the vertebrae, such as lumbar spinal fusion, used PCA for postoperative pain. Patients were randomized to receive either morphine 45 μg/kg or oxycodone 30 μg/kg as i.v. bolus doses. Patients were assessed for pain with a visual analogue scale (VAS) and side effects at 3, 9 and 24 h. Venous blood samples for the measurement of plasma concentration of oxycodone and that of morphine and its metabolites were taken. Results: In this study patients needed, on average, the same amount of oxycodone and morphine in the recovery room and on the ward. There was no difference in the quality of analgesia (VAS) or incidence of side effects, such as nausea, vomiting, pruritus and urinary retention. The plasma concentrations of morphine-6-glucuronide showed that this metabolite might contribute to the analgesia resulting from morphine administration. Conclusions: The same dose of intravenous oxycodone and morphine administered by PCA pump was needed for immediate postoperative analgesia. The two drugs appear to be equipotent.

Incidence of venous and paradoxical air embolism in neurosurgical patients in the sitting position: detection by transesophageal echocardiography

Abstract: Background: Venous air embolism (VAE) and paradoxical air embolism (PAE) are serious complications associated with the sitting position for neurosurgery. Although PAE is the result of VAE, the incidence of PAE according to the severity of VAE has not been investigated systematically in humans. Methods: Twenty-one patients scheduled for neurosurgery in the sitting position were investigated prospectively. VAE and PAE were continuously monitored by cardiac two-dimensional 4-chamber view using transesophageal echocardiography (TEE) and the severity of VAE and PAE was quantitatively graded from 0 to 3 by the microbubbles score. Haemodynamic parameters and end-tidal CO2 concentration (PETCO2) during VAE and PAE were also recorded. Results: Microbubbles in the right atrium appeared in all patients and the number of patients involved in grades 0, 1, 2 and 3 of VAE was 0, 10, 3 and 8, respectively. PAE occurred in 3 patients and only followed grade 3 of VAE. PAE always appeared from 20 to 30 s after the most severe VAE. A reduction of PETCO2 and an increase of pulmonary artery pressure were noted during all episodes of grades 2 and 3 VAE. In contrast, a significant reduction of systemic blood pressure occurred in 1 case of grade 2 and 3 cases of grade 3. Conclusions: VAE detected by TEE appeared in all patients undergoing neurosurgery in the sitting position and PAE only occurred following the most severe grade of VAE. To prevent growth of VAE is an important prophylactic for PAE.

Monitoring perioperative changes in distribution of pulmonary ventilation by functional electrical impedance tomography

Abstract: Background: Electrical impedance tomography (EIT) is a noninvasive technique providing cross-sectional images of the thorax. We have tested an extended evaluation procedure, the functional EIT (f-EIT), to identify the local shifts of ventilation known to occur during the transition between spontaneous, controlled and assisted ventilation modes. Methods: Ten patients scheduled for elective laparotomy were studied in the surgical ward, operating theatre and ICU during spontaneous and different modes of mechanical ventilation. Sixteen ECG electrodes were placed on the circumference of the thorax and connected with an EIT device (APT System Mark I, IBEES, Sheffield, UK). Measurements lasting 180 s were performed and f-EIT images of regional ventilation computed. The geometrical centre of ventilation was determined to quantify the regional distribution of lung ventilation during individual modes of ventilation. Results: F-EIT confirmed the differences in the distribution of ventilation associated with various modes of artificial ventilation. Accentuated ventilation of the dependent lung regions was observed during spontaneous breathing, whereas a shift of the centre of ventilation to the nondependent regions was found during controlled ventilation. In the course of assisted ventilation a continuous displacement of the centre of ventilation back towards the dependent lung regions, consistent with an increased proportion of spontaneous breathing, was detected. Unassisted spontaneous breathing after weaning from mechanical ventilation resulted in a similar ventilation distribution as during tidal breathing prior to surgery. Conclusion: F-EIT determined the redistribution of lung ventilation during different modes of mechanical ventilation. We expect that f-EIT will become a useful noninvasive bedside monitoring technique for imaging regional ventilation in pulmonary diseased patients during mechanical ventilation.

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery: A randomised, double-blind, cross-over study with and without adrenaline

Abstract: Background: Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture. Methods: A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml · h−1 of bupivacaine 1 mg · ml−1, fentanyl 2 μg · ml−1, and adrenaline 2 μg · ml−1 were included. On the 1st and 2nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score. Results: The number of hypaesthetic dermatomal segments decreased (P <0.001) and pain intensity at rest and when coughing increased (P <0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15–20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng · ml−1 (P <0.01), and there was more sedation during the period without adrenaline. Conclusions: Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.

Total intravenous anaesthesia with propofol and remifentanil in paediatric patients: a comparison with a desflurane‐nitrous oxide inhalation anaesthesia

Abstract: BACKGROUND Remifentanil is a new rapid-acting and ultra-short acting mu-opioid receptor agonist with few reports from use in children. Therefore, we compared a propofol-remifentanil-anaesthesia (TIVA) with a desflurane-N2O-anaesthesia (DN) with particular regard to the recovery of characteristics in children. METHODS 50 children (4-11 yr) scheduled for ENT surgery were randomly assigned to receive TIVA (n = 25) or DN (N = 25). After standardised i.v. induction of anaesthesia in both groups with remifentanil, propofol and cisatracurium, TIVA was maintained with infusion of propofol and remifentanil. Ventilation was with oxygen in air. DN was maintained with desflurane in 50% N20. The administration of volatile and intravenous anaesthetics was adjusted to maintain a surgical plane of anaesthesia. At the end of surgery all anaesthetics were terminated without tapering and early emergence and recovery were assessed. In addition, side effects were noted. RESULTS Both anaesthesia methods resulted in stable haemodynamics but significantly higher heart rate with desflurane. Recovery did not differ between the groups except for delayed spontaneous respiration after TIVA. Spontaneous ventilation occurred after 11 +/- 03.7 min versus 7.2 +/- 2.8 min (mean +/- SD, TIVA versus DN), extubation after 11 +/- 3.7 min versus 9.4 +/- 2.9 min, eye opening after 11 +/- 3.9 min versus 14 +/- 7.6 min and Aldrete score > or = 9 after 17 +/- 6.8 min versus 17 +/- 7.5 min. Postoperatively, there was a significant higher incidence of agitation in the DN group (80% vs. 44%) but a low incidence (< 10%) of nausea and vomiting in both groups. CONCLUSION In children, TIVA with remifentanil and propofol is a well-tolerated anaesthesia method, with a lower peroperative heart rate and less postoperative agitation compared with a desflurane-N2O based anaesthesia.

The discriminating power of a risk score for postoperative vomiting in adults undergoing various types of surgery

Abstract: Background: Recently, we have demonstrated that the probability of postoperative vomiting (PV) following ENT surgery with inhalational anaesthetics can be predicted using a risk score. This score is based on gender, age, smoking status, history of motion sickness or postoperative nausea and vomiting and the duration of anaesthesia. Therefore, it is of interest whether this score is also accurate in predicting PV in patients undergoing different types of surgery. Methods: Inpatients scheduled for bone, vascular, general or eye surgery were included in a prospective survey for PV over 24 h. Data of 1091 patients were analyzed, of which 542 were used for the validation of the previously constructed risk score (Score I). The data of the remaining 549 patients were used to evaluate the risk factors that contribute to PV in this setting and to develop a new score (Score II). The discriminating power of both scores to predict PV was tested in the validation set (n=542) and compared by calculating the area under the receiver operating characteristic (ROC) curves. Results: The area under the ROC curve of Score I was 0.77 (SD 0.024). Risk factors for PV in the evaluation set were female gender, young age, history of motion sickness or postoperative nausea and vomiting and the type of surgery. The area under the curve of Score II was 0.75 (SD 0.026) and was not significantly different from Score I (P=0.57). Conclusion: Score I was accurate in predicting PV in patients after most types of surgery with volatile anaesthetics, which suggests that this score might be useful for other centres as well.

Desflurane versus propofol maintenance for outpatient laparoscopic cholecystectomy

Abstract: Background: The aims of the study were to evaluate costs and clinical characteristics of desflurane-based anaesthetic maintenance versus propofol for outpatient cholecystectomy. Methods: All 60 patients received ketamine 0.2 mg kg-1, fentanyl 2 μg kg-1 and propofol 2 mg kg-1 for induction. Ketorolac 0.4 mg kg-1 and ondansetron 0.05 mg kg-1 +droperidol 20 μg Kg-1 was given as prophylaxis for postoperative pain and emesis, respectively. The patients were randomly assigned into Group P with propofol maintenance and opioid supplements, or Group D with desflurane in a low-flow circuit system. Results: All the patients were successfully discharged within 8 h without any serious complications. Emergence from anaesthesia was more rapid after desflurane; they opened their eyes and stated date of birth at mean 6.4 and 8.4 min respectively, compared with 9.6 and 12 min in the propofol group (P<0.05). Nausea and pain were more frequent in Group D, 40% and 80% respectively; versus 17% and 50% in Group P (P<0.05). By telephone interview at 24 h and 7 d after the procedure, there was no major difference between the groups. With desflurane, drug costs per case were 10 $ lower than with propofol. Conclusion: We conclude that desflurane is cheaper and has a more rapid emergence than propofol for outpatient cholecystectomy. However, propofol results in less pain and nausea in the recovery unit. Despite ondansetron and droperidol prophylaxis, there was still a substantial amount of nausea and vomiting after desflurane.

In vitro study on antioxidant potential of various drugs used in the perioperative period.

Abstract: Background:Since surgical trauma not only intensifies the oxidative stress by generating reactive oxygen species (ROS), but also weakens the biological defense system against ROS attack, the antioxidant activity of drugs used during the perioperative period, which possibly normalizes the impaired redox state in the patient, is of fundamental importance and great clinical interest. Methods: We have applied the phycoerythrin fluorescence-based assay, in which 2,2′-azobis (2-amidinopropane) dihydro-chloride (AAPH)-generated peroxyl radical attacks B-phycoerythrin (B-PE) to lead to a sensitive decrease in its fluorescence intensity linearly, to evaluate the antioxidant activity of major drugs in anesthetic practice. Results: By the protective effect on B-PE fluorescence decay, the antioxidant activities of the drugs were classified into three groups: Group I drugs, which only slowed B-PE fluorescence decay (nicardipne, verapamil, diltiazem, ephedrine, aminophyl-line, vecuronium, lidocaine, mepivacaine, midazolam, thiamylal, droperidol, ***etamine, hydroxyzine, butorphanol, prednisolone, hydrocortisone, betamethasone, dexamethasone, methylprednisolone, and furosemide); Group II drugs, which protected B-PE oxidation completely and stopped fluorescence decay in a certain duration (dopamine, epinephrine, norepine-phrine, dobutamine, isoproterenol, and buprenorphine); and Group III drugs, which had no protective effect on B-PE oxidation (nitroglycerin, prostaglandin E1, neostigmine, pancuronium, suxamethonium, atropine, bupivacaine, pentazocine, and heparin). Conclusion: These results indicate that Group I and II drugs exert some antioxidant activity in vitro, as measured by their protection of fluorescence decay of B-PE. Careful consideration of these properties might, then, serve to facilitate more efficient drug application.

Effects of anaesthesia based on high versus low doses of opioids on the cytokine and acute‐phase protein responses in patients undergoing cardiac surgery

Abstract: Background: Cardiac surgery with cardiopulmonary bypass (CPB) evokes a systemic inflammatory response involving the proinflammatory cytokines tumor necrosis factor-α (TNFα), interleukin (iL)-1, IL-6, IL-8 and anti-inflammatory cytokines such as IL-10. Like IL-10, opioids downregulate the immune responses in vivo and in vitro, including the activity of the cytokine-producing monocytes and granulocytes. The proinflammatory cytokines are potent inducers of the hepatic acute-phase protein synthesis. The aim of the present study was to investigate if choice of anaesthesia, based on high-dose opioids (fentanyl) versus low-dose opioids influenced the release of IL-6, IL-8, and IL-10. Secondly, it was investigated whether serum amyloid P-component (SAP) is an acute-phase protein in man such as C-reactive protein (CRP), with which it is physically and structurally related. Methods: Sixteen patients submitted to elective coronary artery bypass grafting (CABG) surgery were randomized to either low-dose opioid anaesthesia consisting of thoracic epidural analgesia combined with inhalational anaesthesia (group I) or high-dose fentanyl anaesthesia (group II). From each patient 18 blood samples were taken perioperatively. Cytokine analyses were performed with ELISA, CRP and SAP mere measured with rocket immunoelectrophoresis (REI). Results: Surgery and CPB elicited a marked, transient and almost simultaneous proinflammatory and anti-inflammatory cytokine response with no differences between the groups. The cytokine levels returned to preoperative levels 1–3 d after operation. Anaesthesia and surgery did not affect SAP plasma levels while patients showed a major increase in CRP concentrations preceding the cytokine responses. Conclusion: CABG performed during two different anaesthetic techniques, high-dose fentanyl versus low-dose opioid anaesthesia, elicited a well-defined cytokine response with minor variation in the time course of each cytokine. The cytokine production was not modified by type of anaesthesia. Finally, SAP is not an acute-phase protein in men.

Porcine-derived surfactant treatment of severe bronchiolitis

Abstract: Background: It is hypothesized that surfactant treatment helps to improve severe bronchiolitis by restoring surfactant system activity. This study aims to assess the effect of surfactant on gas exchange, peak inspiratory pressure and duration of mechanical ventilation and intensive care unit (ICU) stay in children with severe bronchiolitis. Methods: Twenty children with bronchiolitis requiring mechanical ventilation were randomly assigned to one of two groups (10 patients each). Group A was treated with continuous positive pressure ventilation (CPPV) plus surfactant. Group B was treated with CPPV only. Porcine-derived surfactant, 50 mg/kg body weight, was instilled into the trachea. Arterial tension of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, arterial tension of carbon dioxide (PaCO2), and peak inspiratory pressure (PIP) were assessed. Heart rate and non-invasive arterial blood pressure were monitored. The duration of CPPV and the length of ICU stay were also recorded. Finally, the incidence of complications and the survival rate were assessed. Results: In group A, the PaO2/FiO2 ratio significantly improved from 1 h and a reduction in PaCO2 was noted from 12 h. A reduction of PIP was observed from 3 h. The duration of CPPV and the length of ICU stay were reduced in group A. No complications were reported in either group and all children survived. Conclusions: Surfactant treatment of severe bronchiolitis appeared to improve gas exchange, reduce PIP and shorten CPPV and ICU stay. However, these initial results must be confirmed by a larger and more rigorously controlled study.

Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol drug effect and emergence

Abstract: Background: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic drug effect during propofol administration at different calculated plasma target concentrations. Methods: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. Results: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol drug effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. Conclusions: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic drug effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic drug effect.

Is development of hyperalgesia, allodynia and myoclonus related to morphine metabolism during long-term administration? Six case histories.

Abstract: Background: Recently, clinical reports have suggested a relationship between the occurrence of hyperalgesia, allodynia and/or myoclonus and treatment with high doses of morphine in humans. Although few clinical descriptions of these phenomena are available, experimental work supports the notion that high doses of morphine may play a pathogenetic role in the observed behavioural syndrome. Methods: Six patients, four with malignant and two with chronic, non-malignant pain conditions, treated with moderate to high doses of oral, continuous intravenous infusion or intrathecal morphine developed hyperalgesia, allodynia and/or myoclonus. When the side-effects occurred, blood or CSF samples were taken and analyzed for contents of morphine, morphine-6-glucuronide (M-6-G) and morphine-3-glucuronide (M-3-G). Results: When comparing the plasma and CSF concentrations from these patients with data from available literature obtained from patients not suffering from these side-effects, it was demonstrated that the values deviated in five patients. In all six patients, the side-effects disappeared after substituting morphine with other opioid agonists or after lowering the daily dose of morphine. Conclusion: These results may indicate that elevated concentrations of M-3-G in plasma as well as the plasma and CSF M-3-G/M-6-G ratios may play a pathogenetic role in the development of hyperalgesia, allodynia and myoclonus.

Effects of esmolol on haemodynamic response to CO2 pneumoperitoneum for laparoscopic surgery.

Abstract: Background: Carbon dioxide (CO 2 ) pneumoperitoneum for laparoscopic surgery increases arterial pressures, systemic vascular resistance and heart rate and decreases urine output. Methods: In this double-blind randomized study esmolol, an ultrashort-acting β1-adrenoceptor antagonist was compared with physiological saline (control) in 28 patients undergoing laparoscopic surgery in standardized 1 MAC isoflurane anaesthesia. Alfentanil infusion was used to prevent the increase of mean arterial pressure more than 25% from baseline. Results: Esmolol effectively prevented the pressor response to induction and maintenance of CO 2 pneumoperitoneum. Significantly (P<0.001) less alfentanil was needed in the esmolol group than in the control group. Urine output was higher (P<0.05) and plasma renin activity (P<0.01) and urine N-acetyl-β-D-glucosaminidase levels lower in the esmolol group when compared with the control group. Conclusions: Esmolol blunts the pressor response to induction and maintenance of pneumoperitoneum and may protect against renal ischaemia during pneumoperitoneum.

Plasma catecholamines and haemodynamic changes during pneumoperitoneum

Abstract: Background: Insufflation of CO2 into the abdomen is used during all kinds of laparoscopic operations. The procedure elicits haemodynamic and hormonal responses. The reports on sympathetic responses to laparoscopic surgery have been conflicting. However, few studies have assessed sympathetic and haemodynamic responses to CO2 insufflation per se, eliminating possible effects of intubation, skin incision, surgical manipulation and positioning of the body. No studies have measured both venous and arterial plasma catecholamines, the latter being a more sensitive indicator of sympathetic activity. In the present study, we hypothesised an increased sympathetic activity during pneumoperitoneum and an association between haemodynamic and sympathetic responses. Methods: Plasma adrenaline and noradrenaline from the radial artery and superior vena cava were measured immediately before and 10 min after abdominal insufflation of CO2 in 11 subjects. Haemodynamics were monitored invasively. Results: During pneumoperitoneum arterial plasma noradrenaline increased from 155 (106, 209) pg/ml (median, lowest and highest quartile) to 283 (188, 378) pg/ml (P=0.003), while there were no changes in arterial plasma adrenaline. The calculated arterial-superior vena cava difference in plasma noradrenaline did not change, indicating no increased sympathetic activity in the drainage area of the superior vena cava. Heart rate and cardiac index were unchanged, while total peripheral resistance and mean arterial blood pressure increased (P=0.002). The changes in arterial plasma noradrenaline were closely related to the changes in total peripheral resistance (r=0.69, P=0.01). Conclusions: Plasma noradrenaline increases during pneumoperitoneum and is associated with changes in total peripheral resistance. Plasma adrenaline is unchanged and there is no evidence of increased sympathetic outflow to the drainage area of the superior vena cava. Thus, the increase in plasma noradrenaline may be due to more local activation of the sympathetic nervous system, probably somewhere from the drainage area of the inferior vena cava.

Effects of sevoflurane on intracranial pressure, cerebral blood flow and cerebral metabolism. A dose-response study in patients subjected to craniotomy for cerebral tumours.

Abstract: Background: Studies concerning the cerebrovascular effects of sevoflurane in patients with space-occupying lesions are few. This study was carried out as a dose-response study comparing the effects of increasing sevoflurane concentration (1.5% (0.7 MAC) to 2.5% (1.3 MAC)) on cerebral blood flow (CBF), intracranial pressure (ICP), cerebrovascular resistance (CVR), metabolic rate of oxygen (CMRO 2 ) and CO 2 -reactivity in patients subjected to craniotomy for supratentorial brain tumours. Methods: Anaesthesia was induced with propofol/fentanyl/ atracurium and maintained with 1.5% sevoflurane in air/oxygen at normocapnia. Blood pressure was maintained constant by ephedrine. In group 1 (n =10), the patients received continuously 1.5% sevoflurane. Subdural ICP, CBF and CMRO 2 were measured twice at 30-min intervals. In group 2 (n=10), sevoflurane concentration was increased from 1.5% to 2.5% after CBF 1 . CBF 2 was measured after 20 min during 2.5% sevoflurane. Finally, CO 2 -reactivity was studied in both groups. Results: In group 1, no time-dependent alterations in CBF, CVR, ICP and CMRO 2 were found. In group 2, an increase in sevoflurane from 1.5% to 2.5% resulted in an increase in CBF from 29±10 to 34±12 ml 100g -l min -l and a decrease in CVR from 2.7±0.9 to 2.3±1.2 mmHg ml -l min 100g (P<0.05), while ICP and CMRO 2 were unchanged. CO 2 -reactivity was maintained at 1.5% and 2.5% sevoflurane. Conclusion: Sevoflurane is a cerebral vasodilator in patients with cerebral tumours. Sevoflurane increases CBF and decreases CVR in a dose-dependent manner. CO 2 -reactivity is preserved during 1.5% and 2.5% sevoflurane.

Anaesthesia for videoarthroscopy of the knee. A comparison between desflurane and sevoflurane.

Abstract: Background: The newer inhalational agents desflurane and sevoflurane have a low blood-gas partition coefficient and are not very fat soluble, and consequently recovery is rapid and smooth. Very few studies have been published concerning adults where a direct comparison has been made between sevoflurane and desflurane in the ambulatory setting. Methods: This study was done to assess aspects of recovery following minor ambulatory videoarthroscopic knee surgery in 50 ASA I-II patients. Baseline values were obtained on the following psychomotor tests: digit symbol substitution test (DSST), perceptive accuracy test (PAT) and simple reaction time (SRT). The patients were then randomly allocated to one of two groups according to an open (unblinded) study design: Group D (Desflurane) were maintained on desflurane while Group S (Desflurane) were maintained on sevoflurane. Propofol was used as the induction agent in all patients and the larynx mask was used to maintain a free airway. Oxygen and air (FiO2 0.33) were used as the carrier gases. The concentration of desflurane or sevoflurane was adjusted in order to maintain adequate anaesthesia and stable haemodynamics. Alfentanil was given at induction and every 15 min as an analgesic. At the end of the operation, the gases were turned off abruptly and 100% oxygen was delivered at 6 L/min until eye-opening. Early recovery was measured by the time to eye-opening, giving name and date of birth. Intermediate recovery was measured by psychomotor testing every 30 min, and the time to sitting up in bed, drinking fluids and discharge home by a nurse who was blinded to the anaesthetic technique. Results: Early recovery was quicker in the desflurane compared to the sevoflurane group (P<0.001). Psychomotor recovery as measured by the PAT occurred significantly earlier in the desflurane compared to the sevoflurane group at 15 and 45 min (P<0.001) and as measured by the DSST at 30 min (P<0.05). The number of patients who could not perform the SRT test at 15 min was greater in the sevoflurane compared to the desflurane group (13 vs 0) (P<0.01). No differences were found in other recovery parameters, including home discharge, between the groups. The incidence of pain and other minor postoperative complications was similar between the groups except for sore throat which was higher in the desflurane group. Conclusion: Early and intermediate (psychomotor) recovery is quicker in the desflurane compared to the sevoflurane group, but there is no difference in discharge times between the groups.

Cardiovascular effects of two different regional anaesthetic techniques for unilateral leg surgery

Abstract: Background: Cardiovascular function was assessed in 20 ASA I-II patients, scheduled for elective orthopaedic surgery with tourniquet in order to compare the haemodynamic changes induced by unilateral spinal anaesthesia and combined sciaticofemoral nerve block. Methods: After baseline measurement of cardiovascular parameters, patients were randomized to receive unilateral spinal anaesthesia or combined sciatico-femoral nerve block. Spinal anaesthesia was obtained by 8 mg of hyperbaric bupivacaine 0.5% slowly injected (speed=0.02 ml s-1) through a 25-G Whitacre spinal needle with the bevel orientated towards the dependent side and patients lying on their operated side for 15 min (group S, n=10). Combined sciatico-femoral nerve block was obtained by 7 mg kg-1 of mepivacaine 2% (group NB, n = 10). Haemodynamic variables were recorded 5, 10, 15, and 30 min after anaesthetic injection before surgery was started. Results: Anthropometric data, duration of surgery and acceptability of anaesthetic techniques were similar in the 2 groups. In 8 patients of group S, spinal block was restricted to the operated side (pinprick test and Bromage scale), while the other 2 patients developed bilateral spinal block after being turned supine. NB patients showed no haemodynamic changes during the study, whereas patients in group S showed a small but significant decrease of mean arterial blood pressure (P<0.002 vs baseline and P<0.04 vs NB), cardiac index (P<0.01 vs baseline and P0.01 vs NB), and stroke volume index (P<0.01 vs baseline and P<0.01 vs NB). Conclusion: Both sciatico-femoral and unilateral spinal blockade provide adequate anaesthesia for unilateral leg surgery with tourniquet. The former technique affects cardiovascular performance less than the latter one.

Changing preoperative fasting policies : Impact of a national consensus

Abstract: Background: Liberalisation of preoperative fasting rules has been discussed and recommended in the anaesthesia literature in recent years. In Norway, a national consensus on this issue was reached in 1993. The aim of the present study was to investigate whether a national consensus on fasting recommendations led to a change in fasting policies in Norwegian anaesthesia departments. Methods: A questionnaire on preoperative fasting routines was sent to all Norwegian anaesthesia departments in 1993 and repeated in 1996. Results: Written local guidelines for preoperative fasting were present in 85% of the institutions in both surveys. Of the hospitals, 69% had changed their local guidelines after the national consensus. In 1996 more hospitals allowed less than 6 h fasting for clear liquids in children (93% versus 71% in 1993; P<0.005). A similar tendency was noted in adults (79% versus 63% in 1993; P=0.1). In contradiction to the national guidelines, 31% of the departments reported that they allowed less than 6 h fasting after a light breakfast in the morning of surgery in 1996. The corresponding number for 1993 was 21% (ns). Conclusion: The new, consensus-based national fasting guidelines have been associated with a change towards more liberal fasting policies in Norwegian departments of anaesthesia. However, as not all local changes were supported by the national consensus, other sources of information were used when local policies were decided.

Tactile evaluation of the response to double burst stimulation decreases, but does not eliminate, the problem of postoperative residual paralysis.

Abstract: Background: Routine perioperative monitoring with accelero-myography might prevent residual block, whereas routine tactile evaluation of the response to train-of-four (TOF) nerve stimulation does not. The purpose of this prospective, randomised and blinded study was to evaluate the effect of manual evaluation of the response to double burst stimulation (DBS3.3) upon the incidence of residual block. Methods: Sixty adult patients scheduled for elective abdominal surgery were included in the study. Pancuronium 0.08 to 0.1 mg kg−1 was given for relaxation and tracheal intubation. For maintenance of neuromuscular block, pancuronium 1–2 mg was administered. The patients were randomly allocated into two groups. In group DBS (double burst stimulation) the degree of block during anaesthesia was assessed by manual evaluation of the response to TOF nerve stimulation. During reversal, when no fade was detectable in the TOF response, the stimulation pattern was changed to DBS3.3. The trachea was extubated when the anaesthetist judged the neuromuscular function to have recovered adequately and no fade in the DBS3.3 response could be felt. In group CC (clinical criteria) patients were managed without the use of a nerve stimulator, and the level of neuromuscular block and reversal were evaluated solely on the basis of clinical criteria. In both groups, the TOF ratio was measured by mechanomyography immediately after tracheal extubation. Also, the ability to sustain head lift for 5 s, to protrude the tongue, to open the eyes, and to lift one arm to the opposite shoulder were tested. Results: The TOF ratio, as measured immediately after tracheal extubation, was significantly lower in group CC than in group DBS (means: 0.68 and 0.78, respectively), and the incidence of residual neuromuscular block defined as a TOF ratio <0.7 was significantly higher in group CC than in group DBS (57 and 24%, respectively). The time from the first TOF measurement until the TOF ratio reached 0.8 was significantly longer in group CC than in group DBS (means: 11.5 and 6.2 min, respectively). No significant differences between the two groups of patients were found in duration of anaesthesia, in times from end of surgery to injection of neostigmine, tracheal extubation or TOF ratio 0.8, in dose of pancuronium, or in any other postoperative variable. Conclusion: Routine perioperative manual evaluation of the responses to TOF and DBS3.3 decreased the incidence and the degree of residual block following the use of pancuronium. It did not, however, exclude clinically significant residual paralysis, nor did it influence the amount of pancuronium used during the operation, the duration of anaesthesia or the time from end of surgery to tracheal extubation or to sufficient recovery of neuromuscular function (TOF=0.8).

Comparison of transarterial and multiple nerve stimulation techniques for an initial axillary block by 45 mL of mepivacaine 1% with adrenaline.

Abstract: Background: The single-injection axillary block is rapidly performed but gives unpredictable results. Axillary block by multiple nerve stimulation technique (MNS) gives better results, but takes longer to perform. Transarterial (TA) injections of high doses of local anaesthetics are very successful. This double-blind study compared both block effectiveness and anaesthesiologic time consumption in 100 patients, having an axillary block by either TA or MNS techniques. Methods: 45 mL of 1% mepivacaine with adrenaline 5 μg/mL was used in each patient. Five mL was injected subcutaneously. In the TA group, 20 mL was injected deep to, and 20 mL superficial to the axillary artery. In the MNS group, four terminal motor nerves were electrolocated in the axilla, and injected with 10 mL each. Analgesia was assessed every 10 min and when needed supplemented after 30 min. The block was considered successful when analgesia was present in all sensory nerve areas distal to the elbow. Results: MNS group required 10±2 min (mean±1 SD) for the initial block performance compared with 7±2 min for TA group, P<0.001. Latency of the initial block was shorter and the frequency of supplemental analgesia lower in the MNS group (mean 17 min and 12%), than in the TA group (25 min and 38%, respectively), P<0.001. All incomplete blocks were successfully supplemented by electrolocating the unblocked nerves. However, the total time to obtain 100% success rate was shorter in the MNS group (30 min), than in the TA group (38 min), P<0.001. The adverse effects (accidental intravascular injections and axillary haematomas) were fewer in the MNS group. Conclusion: In the hands of anaesthetists experienced in nerve electrolocation, the MNS technique of an initial axillary block by four separate injections of 10 mL of mepivacaine produces faster and more extensive block than the TA technique by two separate injections of 20 mL. Hence, the MNS technique requires fewer supplementary blocks and results in faster patient readiness for surgery than the TA technique.

Analgesic efficacy and safety of preoperative versus postoperative ketorolac in paediatric tonsillectomy.

Abstract: Background: Tonsillectomy is a common procedure in childhood resulting in significant morbidity due to pain. The aim of this study was to evaluate the analgesic efficacy and safety of a single dose of ketorolac i.v. given before or after tonsillectomy, compared to placebo. Methods: A randomized, double-blind, placebo-controlled study was performed in 60 children, 5 to 15 years of age, admitted for tonsillectomy Patients were allocated to receive ketorolac 1 mg . kg-1 i.v. or placebo. Postoperative pain was assessed by self-report 1.5, 3, 5, and 24 h after surgery. Results: Pain scores were significantly lower for both ketorolac groups compared to the placebo group 1.5, 3, and 5 h after surgery (P<0.05). Pain scores were lowest in the preoperative ketorolac group 1.5 to 5 h after surgery, and significantly fewer children in this group had fentanyl 0 to 1.5 h after surgery. But no significant differences were found between pain scores of the preoperative and postoperative ketorolac groups in the first 24 h after surgery. Acetaminophen consumption during the first 5 h after surgery was significantly less in patients receiving ketorolac (P<0.05). Patients in the preoperative ketorolac group had a significantly lower incidence of postoperative vomiting (P<0.05). There were no significant differences in the incidence of postoperative bleeding between groups. Three children in the preoperative, 5 children in the postoperative ketorolac group, and 5 children in the placebo group experienced postoperative haemorrhage. Conclusion: This study indicates that a single dose of ketorolac 1 mg . kg-1 i.v. administered either before or immediately after surgery improves postoperative analgesia in children after tonsillectomy without evidence of increased incidence of bleeding.

Obstetric outcome following epidural analgesia with bupivacaine-adrenaline 0.25% or bupivacaine 0.125% with sufentanil--a prospective randomized controlled study in 1000 parturients.

Abstract: Background: Epidural analgesia (EDA) is the most efficient method for pain relief during labour, but there is still a debate as to whether it interferes with the normal process of delivery. Some authors argue that the incidence of instrumental deliveries, Caesarean section, malrotation and protracted labour is increased in parturients receiving EDA. Methods: 1000 parturients were prospectively randomized to receive EDA either with a high dose of local anaesthetic (0.25% bupivacaine with adrenaline=HD) or with a low dose (0.125% bupivacaine with sufentanil 10 μg=LD). Results: The incidence of instrumental delivery and Caesarean section and the need for oxytocin was reduced in the LD compared to HD group. The delivery time was similar with HD and LD among primiparous, but decreased significantly among multiparous in the LD group. The incidence of malrotation was low in both groups. The quality of analgesia was equal during the first stage in the 2 groups, but was lower in the LD group during the second stage. More parturients in the LD group ambulated, but this did not affect the incidence of instrumental delivery. Conclusion: It is concluded that a lower dosage of bupivacaine combined with sufentanil in epidural analgesia significantly improves the obstetric outcome as compared to a higher dosage of bupivacaine with adrenaline using intermittent bolus technique.

Transient radicular irritation after spinal anesthesia induced with hyperbaric solutions of cerebrospinal fluid‐diluted lidocaine 50 mg/ml or mepivacaine 40 mg/ml or bupivacaine 5 mg/ml

Abstract: Background: Transient radicular irritation (TRI) is common after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml. The purpose of this study was to determine the incidence of TRI after spinal anesthesia with hyperbaric lidocaine 50 mg/ ml diluted with cerebrospinal fluid (CSF) 1:1 and hyperbaric mepivacaine 40 mg/ml and hyperbaric bupivacaine 5 mg/ml. Methods: Ninety ASA class I-IV patients undergoing mostly brief urological procedures under spinal anesthesia were randomly allocated to receive either hyperbaric lidocaine 50 mg/ ml diluted with CSF 1:1 (Group L), hyperbaric mepivacaine 40 mg/ml (Group M) or hyperbaric bupivacaine 5 mg/ml (Group B). Characteristics of the patients and details of the surgical procedures and spinal anesthesias were similar in all groups except for the intensity of motor block. The patients were evaluated on the first postoperative day by an anesthesiologist who did not know which spinal anesthetic agent had been used. Results: Six patients (20%) in Group L, 11 patients (37%) in Group M and none (0%) in Group B experienced pain in the legs and /or back (TRI) after spinal anesthesia. Conclusion: TRI is frequent after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml diluted with CSF 1:1. The incidence of TRI after hyperbaric mepivacaine 40 mg/ml is of the same magnitude. TRI could not be observed after bupivacaine spinal anesthesia.

Effects of intravenous anesthetics on bacterial elimination in human blood in vitro

Abstract: Backround: Since anesthetics are widely used in critically ill patients, this study investigates anesthetic effects on neutrophil and monocyte function concerning bacterial elimination in human whole blood. Methods: The effects of thiopental (20 and 200 μg/ml), propofol (5 and 50 μg/ml), midazolam (0.15 and 1.5 μg/ml) and ketamine (3 and 30 μg/ml) on elimination of Escherichia (E.) coli from whole blood were investigated in vitro after incubation for 1 h in both clinical (1) (n=10) and 10-fold higher (h) (n=11) concentrations. These data were compared to neutrophil and monocyte phagocytosis (1; n=6) and burst activity (1; n=10, h; n=11), measured by flow cytometry. To enable quantification of the clearance process, a defined number of 10 5 colony forming units of E. coli were added to the blood assays and bacterial growth was determined. Results: All anesthetics delayed bacterial clearance from the blood in the 10-fold concentration (P<0.05). Thiopental (1+h) and propofol (h) suppressed neutrophil (59±3% and 38±6%) and monocytic (45±6% and 30±11%) oxidative burst (P<0.01). Phagocytosis was reduced even after propofol (1) in polymorphonuclear leukocytes (PMN) (34±9%; P<0.05) and monocytes (35±11%). Ketamine (h) prolonged bacterial elimination (P<0.01), which did correlate with inhibition of monocytic phagocytosis, by 26±14%. Midazolam application (h) resulted in an inhibition of PMN-respiratory burst by 19±6% (P<0.05) and impaired bacterial clearance (P<0.05). Conclusion: Thiopental, propofol, midazolam and ketamine affect E. coli clearance and neutrophil and monocyte oxidative burst and phagocytosis in vitro only in high concentrations, while thiopental inhibited monocytic burst and propofol impaired PMN phagocytosis even in clinically used concentrations. These data suggest that i.v. anesthetics in concentrations recommended for general anesthesia seem to have minor influence on the investigated host defense mechanisms.

Intraoperative autotransfusion is associated with modest reduction of allogeneic transfusion in prosthetic hip surgery.

Abstract: Background: The efficacy of intraoperative salvage and washing of wound blood and the predictors of allogeneic red cell transfusions in prosthetic hip surgery are insufficiently known. Methods: In 96 patients, undergoing primary or revision surgery, salvaged and washed red cells and, if necessary, allogeneic blood were used to keep haematocrit not lower than 33%. The bleeding of red cells during hospital stay was calculated from the red cell balance. The preoperative red cell reserve (millilitres of red cells in excess of a haematocrit of 33%) was estimated and the difference between this volume and the total bleeding of red cells was retrospectively used to classify patients with regard to the need for red cells. Stepwise regression analysis was used to define patient-related variables associated with allogeneic blood transfusion. Results: Preoperative knowledge of the type of operation (primary, revision), the preoperative red cell reserve, and the body mass could predict roughly half of the need for banked blood (r2=0.45). Only one-third of the total bleeding of red cells was retransfused. For complete avoidance of allogeneic blood, autotransfusion was most effective in patients with a moderate need (0–4 u). However, 32% of such patients required allogeneic blood. Conclusions: Autotransfusion has a limited efficacy to decrease the need for allogeneic blood, and other blood-saving methods should be added for this purpose. It is difficult to predict the need for allogeneic blood preoperatively.