Summary

Background and objective: Astrocytes exposed to hypoxia produce pro-inflammatory cytokines and upregulate intercellular adhesion molecule-1 on cerebral endothelium. This study investigated the effects of midazolam on this response. Methods: Mouse astrocytes were exposed to 4 h of hypoxia and 24 h of reoxygenation. Astrocyte-conditioned medium were applied to mouse cerebral endothelial cell cultures for 4 h and 24 h in normoxia. Endothelial cells were pre-incubated for 1 h with midazolam (0, 5, 50 μg L−1). Flow cytometry was used to estimate endothelial ICAM-1 expression. IL-1β concentrations were measured with ELISA. Repeated comparisons were made using ANOVA and post hoc Tukey Test as appropriate. Data are mean (SD). Results: Mouse cerebral endothelial cell ICAM-1 expression was greater after 24 h exposure to hypoxia–reoxygenation astrocyte-conditioned medium compared to normoxic astrocyte-conditioned medium (mean channel flouresence 112.5 (9.5) vs. 81.5 (7.5), P = 0.01). ICAM-1 expression was decreased by midazolam (5 μg L−1) compared to control (mean channel flouresence 81.35 (7.5) vs. 112.5 (9.5), P = 0.01). Supernatant IL-1β concentrations (pg mL−1) in astrocytes exposed to hypoxia–reoxygenation were greater than those exposed to normoxia (16.41 (2.35) vs. 10.5 (2.13), P = 0.01). Conclusion: We conclude that decreased cerebral endothelial ICAM-1 expression in response to activated glial cell compartment by midazolam may decrease post ischaemic brain inflammation and secondary brain injury.

Summary

Background and objective: This randomized, prospective study was performed to evaluate the efficacy of a subcutaneous local anaesthetic infiltration prior to venepuncture using different cannula sizes.

Methods: Three-hundred-and-one patients were included in the study, 150 received mepivacaine 1% (0.25 mL) subcutaneously, 151 were cannulated without local analgesia. Patients were further allocated to one of five cannula size groups (standard wire gauge (G)): 20-, 18-, 17-, 16- and 14-G. They were asked to quantify the pain experienced using a four-point rating scale.

Results: In the group without local anaesthetics, 28.8% complained about pain compared to 12% receiving local analgesia. The incidence of pain for 14-G (10%) and 16-G (12.9%) cannulae was significantly reduced in the local analgesia group (P < 0.01) compared to no local analgesia (77.4% and 45.1%). Other cannula sizes showed no difference in pain whether using local analgesia or not.

Conclusions: Patients profit from a subcutaneous infiltration with mepivacaine 1% prior to intravenous cathetherization only when cannulae of size ≥16-G are inserted.

Summary

Background and objective: In this preliminary study we wanted to explore the attitudes of anaesthesiologists to a point-of-care information system in the operating room. The study was conducted as a preliminary step in the process of developing such a system by the European Society of Anaesthesiologists (ESA).

Methods: A questionnaire was distributed to all 2240 attendees of the ESA's annual meeting in Gothenburg, Sweden, which took place in April 2001.

Results: Of the 329 responders (response rate of 14.6%), 79% were qualified specialists with more than 10 yr of experience (68%), mostly from Western Europe. Most responders admitted to regularly experiencing lack of medical knowledge relating to real-time patient care at least once a month (74%) or at least once a week (46%), and 39% admitted to having made errors during anaesthesia due to lack of medical information that can be other-wise found in a handbook. The choice of a less optimal but more familiar approach to patient management due to lack of knowledge was reported by 37%. Eighty-eight percent of responders believe that having a point-of-care information system for the anaesthesiologists in the operating room is either important or very important.

Conclusions: This preliminary survey demonstrates that lack of knowledge of anaesthesiologists may be a significant source of medical errors in the operating room, and suggests that a point-of-care information system for the anaesthesiologist may be of value.

Summary

Background and objective: This study was designed to determine which single bolus dose of remifentanil in combination with propofol and nitrous oxide is best to control the haemodynamic, autonomous and somatic responses in patients scheduled for dilatation and curettage of the uterine cervix. We evaluated the adequacy of different bolus doses of remifentanil, associated with propofol and nitrous oxide, for dilatation and curettage in a prospective double-blind study.

Methods: After institutional approval and informed consent, 34 healthy females undergoing curettage to remove material from the uterus after spontaneous abortion were randomized to receive remifentanil 0.5 μg kg−1 intravenously (i.v.) (Group A; n = 4), 1 μg kg−1 i.v. (Group B; n = 15) or 1.5 μg kg−1 i.v. (Group C; n = 15), with propofol 2 mg kg−1 i.v. in all groups. Anaesthesia was maintained with 60% nitrous oxide in oxygen. Haemodynamic, somatic and autonomic signs of light anaesthesia were registered to assess the response to surgical stress. Recovery times and Aldrete score were recorded at the end of the procedure.

Results: The groups were similar with regard to biometric data and duration of surgery. The poor results using the lowest dose of remifentanil obliged us to abandon this dose. The total dose of remifentanil was larger in Group C (100 ± 5.7 μg vs. 65 ± 4.1 μg in Group B; P < 0.05), but more patients required extra bolus injections in Group B (69% vs. 38% in Group C; P < 0.01). Recovery times were significantly shorter in Group C. Aldrete scores when leaving the operation room was similar.

Conclusions: Remifentanil 1.5 μg kg−1 i.v. with propofol 2 mg kg−1 i.v. and 60% nitrous oxide in oxygen provided the best anaesthetic control with the fastest recovery times.

Background and objective: Epidural analgesia with bupivacaine plus either sufentanil or fentanyl is widely used during labour, but it is not clear which opioid is to be preferred. The study compared these opioids at equianalgesic doses in terms of analgesia, onset time and side-effects.

Methods: Ninety females in active labour were entered into the randomized, double-blind trial. A test dose of bupivacaine was given into the epidural space. Parturients in Group S received sufentanil 8 mL as a bolus dose, followed by an infusion at a rate of 5 mL h−1 of a mixture containing sufentanil 1 µg mL−1 and bupivacaine 1 mg mL−1. Patients in Group F received fentanyl 8 mL as a bolus, followed by an infusion at 5 mL h−1 of a solution containing fentanyl 3.5 µg mL−1 and bupivacaine 1 mg mL−1. Additional boluses of 5 mL were of the relevant solution were given if necessary.

Results: In a ratio of 1.0 : 3.5 (sufentanil 1 µg versus fentanyl 3.5 µg), both groups reported the same analgesia with the same onset time. The onset time to obtain 50% of the initial visual analogue score was 10 and 11 min for Groups S and F, respectively. Mean visual analogue scores in Groups S and F respectively declined from 77 and 82 before epidural blockade, to 29 and 27 during the first stage of labour, and to 69 and 59 respectively during the second stage. Overall satisfaction among parturients was high (98 and 96%), particularly during the first stage (98 and 98%), and also to a large degree during the second stage of labour (74 and 79%). Furthermore, only a few extra bolus doses were required (mean 0.9 and 1.2, Groups S and F, respectively). All the females could stand on their own, and almost all (81% Group S; 79% Group F) could walk 20 m without help. There were no serious adverse effects. Moderate side-effects occurred equally often with the possible exception of less nausea and vomiting in the fentanyl group.

Conclusions: Epidural analgesia for ambulatory parturients with bupivacaine plus either sufentanil or fentanyl (ratio 1.0 : 3.5) provides good analgesia with a low frequency of modest side-effects. No clinical differences were found between the opioids.

At clinically relevant concentrations, volatile anaesthetic agents influence neutrophil function. Our hypothesis was that sevoflurane would inhibit neutrophil apoptosis and consequently influence the postoperative pro-inflammatory state. In order to identify selectively the effect of the anaesthetic agent sevoflurane, we studied patients undergoing minimally stimulating (cataract) surgery randomly allocated to receive either sevoflurane (n=11) or local anaesthesia (n=12). Venous blood samples were taken immediately prior to anaesthesia and at 1, 8 and 24 h thereafter. The rate of neutrophil apoptosis, plasma concentration of cytokines and differential white cell count were measured. The rates of neutrophil apoptosis and plasma concentrations of IL-1β, TNF-α and IL-8 at each time point were similar in the two groups. IL-6 concentrations increased significantly and to a similar extent compared to preanaesthetic levels at 8 and 24 h. This study demonstrates that sevoflurane does not influence the rate of neutrophil apoptosis, cytokine concentrations and neutrophil count following cataract surgery.

Summary

Background and aim: Rocuronium may be given to patients for intubation and also after they have received suxamethonium for intubation. The neuromuscular profile of rocuronium given after recovery from suxamethonium may not be identical to that when rocuronium has been given alone. The neuromuscular effects of suxamethonium and rocuronium, and their effects on intraocular pressure (IOP), heart rate (HR) and arterial pressure were also recorded.

Methods: Thirty patients were randomly allocated to receive either 0.6 mg kg−1 rocuronium (n = 15) or 1 mg kg−1 suxamethonium (n = 15) for intubation. Anaesthesia was first induced using propofol 2.5 mg kg−1 and fentanyl 2 μg kg−1 and maintained with propofol 6–12 mg kg−1h−1. The response of the thumb to supramaximal train-of-four (TOF) ulnar nerve stimulation at the wrist was measured using a mechanomyograph. In the suxamethonium group, when the first twitch of the TOF had recovered to 90%, rocuronium 0.6 mg kg−1 was administered. Before administration of relaxant, baseline readings of HR, arterial pressure and IOP were measured until stable, then the appropriate relaxant administered. Thereafter, all readings were repeated at 30, 90, 150, 210 and 270 s. Tracheal intubation was performed 300 s after the intubating dose and all recordings repeated 30 s later. Mechanomyographic monitoring was continued until 70% TOF recovery.

Results: Suxamethonium had a more rapid onset than rocuronium (49 s vs. 74 s, P < 0.0001). The onset time of rocuronium after suxamethonium was significantly reduced (56 s) and the time to recover to a TOF of 70% following rocuronium was increased by previous suxamethonium administration (47 vs. 58 min, P < 0.05). Suxamethonium caused a marked rise in IOP (>30%) and HR (>10%) while rocuronium had little effect on either.

Conclusion: Previous suxamethonium administration decreases the onset time and increases the duration of action of rocuronium. Unlike suxamethonium, rocuronium has few cardiovascular effects and causes little change in IOP.

Summary

Background and objectives: This study was undertaken to compare the effect of alpha-stat vs. pH-stat strategies for acid–base management on regional cerebral oxygen saturation (RsO2) in patients undergoing moderate hypothermic haemodilution cardiopulmonary bypass (CPB). Methods: In 14 adult patients undergoing elective coronary artery bypass grafting, an awake RsO2 baseline value was monitored using a cerebral oximeter (INVOS 5100). Cerebral oximetry was then monitored continuously following anaesthesia and during the whole period of CPB. Mean ± SD of RsO2, CO2, mean arterial pressure and haematocrit were determined before bypass and during the moderate hypothermic phase of the CPB using the alpha-stat followed by pH-stat strategies of acid–base management. Alpha-stat was then maintained throughout the whole period of CPB. Results: The mean baseline RsO2 in the awake patient breathing room air was 59.6 ± 5.3%. Following anaesthesia and ventilation with 100% oxygen, RsO2 increased up to 75.9 ± 6.7%. Going on bypass, RsO2 significantly decreased from a pre-bypass value of 75.9 ± 6.7% to 62.9 ± 6.3% during the initial phase of alpha-stat strategy. Shifting to pH-stat strategy resulted in a significant increase of RsO2 from 62.9 ± 6.3% to 72.1 ± 6.6%. Resuming the alpha-stat strategy resulted in a significant decrease of RsO2 to 62.9 ± 7.8% which was similar to the RsO2 value during the initial phase of alpha-stat. Conclusion: During moderate hypothermic haemodilutional CPB, the RsO2 was significantly higher during the pH-stat than during the alpha-stat strategy. However, the RsO2 during pH-stat management was significantly higher than the baseline RsO2 value in the awake patient breathing room air, denoting luxury cerebral perfusion. In contrast, the RsO2 during alpha-stat was only slightly higher than the baseline RsO2, suggesting that the alpha-stat strategy avoids luxury perfusion, but can maintain adequate cerebral oxygen supply-demand balance during moderate hypothermic haemodilutional CPB.

Photodynamic therapy is an innovative modality in the treatment of malignant and non-malignant diseases. Owing to its widespread use, there will be an increase in the number of photosensitized patients presenting for both elective and emergency anaesthesia. As one of the few centres involved in providing this specialized treatment for maxillofacial conditions, we would like to highlight its main anaesthetic considerations.

Direct muscular stimulation is quick, simple, non-invasive and can be carried out at the patient’s bedside. More importantly, it is reliable even when the patients cannot cooperate or are comatose. From the small amount of data available, it seems to be as accurate as neuromuscular biopsy in diagnosing critical illness myopathy. It would therefore be advisable to use it in everyday clinical practice.

Background and objective Inflammatory liver dysfunction in rats leads to a prolonged vecuronium-induced neuromuscular blockade due to insufficient metabolism. A coexisting resistance against the drug partly counteracts this prolongation. The present study investigates the pharmacodynamics of atracurium whose metabolism does not depend on liver function.

Methods Male Sprague–Dawley rats (n = 14; 290 ± 30 g) were randomly allocated to either a group in which liver inflammation was induced by intravenous injection of 60 mg kg−1 heat-killed Corynebacterium parvum or to a control group. On day 5 after injection, liver function was assessed using the aminopyrine breath test. Under propofol anaesthesia, duration of action of atracurium (4.8 mg kg−1) was measured by evoked mechanomyography (stimulation of the sciatic nerve; contraction of the gastrocnemius muscle). Nitric oxide concentrations, as variables for the severity of the inflammation, were assessed by measurement of nitrite/nitrate plasma concentrations.

Results In C. parvum-injected rats, nitrite/nitrate plasma concentrations were increased (972 ± 597 vs. 25 ± 7 μmol L−1), the aminopyrine turnover was depressed (1.7 ± 0.4% vs. 3.5 ± 0.5%), and the atracurium-induced neuromuscular blockade was shortened (372 ± 128 s vs. 1081 ± 234 s).

Conclusions A systemic inflammatory response syndrome with liver dysfunction results in decreased sensitivity to atracurium. Further investigations are needed regarding a possible up-regulation of acetylcholine receptors or an increased protein binding of atracurium during sepsis to clarify reasons behind this phenomenon.

Background and objective: Target-controlled infusions of anaesthetic agents have become increasingly available. They can involve the use of propofol in combination with an opioid or a benzodiazepine. The effect site concentration of propofol infusions has been advocated as a method of estimating drug distribution. We investigated the influence of co-induction with remifentanil and midazolam on effect site propofol requirements at induction of anaesthesia using target-controlled infusions.

Methods: Sixty-six consenting adult patients were randomly allocated to three treatment groups. Each group received induction of anaesthesia with a different total intravenous technique. One group was induced with target-controlled propofol alone; another received target-controlled propofol and target-controlled remifentanil (3 ng mL−1); and the last received midazolam (0.03 mg kg−1), target-controlled remifentanil (3 ng mL−1) and target-controlled propofol. Computer simulation was used to calculate effect site concentrations. We recorded propofol dose and effect site concentration at loss of verbal response.

Results: The effect site concentration (Ce50) of propofol alone was 2.19 µg mL−1. This was reduced to 1.55 µg mL−1 during co-induction with remifentanil and further reduced to 0.64 µg mL−1 with midazolam premedication (P < 0.001; ANOVA).

Conclusions: We conclude that co-induction with remifentanil alone or with midazolam can be used to reduce propofol doses at induction of anaesthesia using target-controlled infusions. We believe that using effect site concentration may prove a useful tool in routine clinical practice.

Summary

Background and objective: Sub-Tenon's block is usually delivered by the infero-nasal (IN) approach, but occasionally this may not be possible. The infero-temporal (IT) approach has been described, but data is not available on its efficacy. Methods: One hundred patients undergoing cataract extraction were randomized to receive an IN or IT sub-Tenon's injection of lidocaine 2% with hyaluronidase 15 IU mL−1. Akinesia was assessed using the Brahma scale at 0, 2, 4, 6 and 8 min. Injection, intraoperative and postoperative pain scores (verbal analogue score, 0–10) were noted, along with the incidence of sub-conjunctival haemorrhage and chemosis. Results: There were no differences in patient characteristics data, or mean volume of administered local anaesthetic solution (3.3 (SD = 0.4) mL). There were no significant differences between groups in terms of onset of akinesia. Mean akinesia scores at 2, 4, 6 and 8 min were 2.7, 1.1, 0.4 and 0.2 for Group IN, compared to 2.2, 0.9, 0.8 and 0.3 for Group IT. Chemosis occurred in 14 patients in Group IN, compared to 22 in Group IT (P = 0.21).A sub-conjunctival haemorrhage was noted in 14 patients in Group IN and 19 patients in Group IT (P = 0.52). No patients required supplementary injections. Mean pain scores for the injection, intraoperatively and postoperatively were 0.9, 0 and 0 for Group IN, compared to 1.1, 0 and 0 for group IT. The surgeons scored all the blocks as ‘good’ except for one patient in each group. Conclusions: The IT approach provides an equally rapid onset of block, without a significant increase in complications.

Summary

Background and objective: Hydroxyethyl starch is frequently used for volume substitution during surgical procedures and for isovolaemic haemodilution. Haemodilution has also been shown to improve tissue oxygen tension in skeletal muscle. However, effects of this volume substitute on tissue oxygen tension of the liver during haemodilution remains unknown.

Methods: Fourteen foxhounds were anaesthetized with fentanyl/midazolam and mechanically ventilated with 30% oxygen. Following splenectomy animals were randomly assigned to a control group without haemodilution but fluid substitution with Ringer's lactate (Group C) or underwent isovolaemic haemodilution to a haematocrit of 25% with hydroxyethyl starch 70/0.5 (Group H). Haemodynamic parameters and oxygen transport during 100 min following isovolaemic haemodilution were measured. Liver oxygen tension was recorded using a flexible polarographic electrode tonometer, whereas in the muscle a polarographic needle probe was used.

Results: Animal characteristics and baseline haematocrit were similar in both groups. At baseline the tissue oxygen tension of liver and skeletal muscle were not different between groups. Haemodilution with hydroxyethyl starch 70/0.5 provided augmentation of mean liver tissue oxygen tension (baseline: 46 ± 13 mmHg; 20 min: 60.3 ± 12 mmHg*; 60 min: 60 ± 16 mmHg*; 100 min: 63 ± 16 mmHg*; *P < 0.05 vs. baseline), while oxygen tensions in Group C remained unchanged (baseline: 48 ± 16 mmHg; 20 min: 52 ± 19 mmHg; 60 min: 49 ± 12 mmHg; 100 min: 52 ± 16 mmHg) and no differences could be detected between groups. Oxygen tension in skeletal muscle changed as follows: Group H – baseline: 24 ± 32 mmHg; 20 min: 32 ± 3 mmHg*[dagger]; 60 min: 33 ± 7 mmHg*[dagger]; 100 min: 33 ± 11 mmHg[dagger]. Group C – baseline: 22 ± 6 mmHg; 20 min: 21 ± 3 mmHg; 60 min: 24 ± 4 mmHg; 100 min: 18 ± 4 mmHg (*P < 0.05 vs. baseline, [dagger]P < 0.05 vs. Group C).

Conclusion: In this animal model, isovolaemic haemodilution with hydroxyethyl starch 70/0.5 increased tissue oxygen tension in liver and skeletal muscle in comparison with baseline values. However, when compared between groups haemodilution only resulted in an increase of tissue oxygen tension in the muscle but not in the liver.

Background and objective: The efficiency of operating room times can be significantly improved using rapid changes between operative procedures. We performed a retrospective analysis using electronic anaesthesia charts that compared anaesthesia-related times between the three most frequently performed types of anaesthesia (for orthopaedic surgery) to evaluate the potential for a quicker turn-around between cases.

Methods: A total of 5614 anaesthetic procedures in trauma-related orthopaedic surgery were performed from 1997 to 1999. All were documented with an automatic record-keeping system. Data were compared for intravenous anaesthesia with the laryngeal mask airway, balanced anaesthesia with tracheal intubation and regional anaesthesia. The primary outcome measure was the time needed for emergence from anaesthesia after the end of surgery. Statistical evaluation was performed with matched triples for all three types of anaesthesia (155 triples for ambulatory surgery, 249 triples for in-patient care).

Results: For ambulatory surgery, the induction time was significantly shorter for general anaesthesia (23.7 min for intravenous anaesthesia, 22.7 min for balanced anaesthesia techniques) compared with regional anaesthesia (27.2 min). The time from the end of the surgical procedure to transfer of the patient out of the operating room was shortest for regional anaesthesia (6.3 min) compared with intravenous anaesthesia (9.0 min) and balanced anaesthesia (12.5 min) techniques. Results were comparable for in-patients: regional anaesthesia required significantly longer for its induction, but less time for patient discharge from the operating room.

Conclusions: The use of a regional anaesthesia technique or one involving intravenous anaesthesia in combination with the laryngeal mask airway may lead to a reduction in discharge time compared with a balanced anaesthesia technique with endotracheal intubation. Thus, improved use of resources may be achieved.