Summary

Background: Short-acting agents for neuromuscular block (NMB) require frequent dosing adjustments for individual patient's needs. In this study, we verified a new closed-loop controller for mivacurium dosing in clinical trials. Methods: Fifteen patients were studied. T1% measured with electromyography was used as input signal for the model-based controller. After induction of propofol/opiate anaesthesia, stabilization of baseline electromyography signal was awaited and a bolus of 0.3 mg kg−1 mivacurium was then administered to facilitate endotracheal intubation. Closed-loop infusion was started thereafter, targeting a neuromuscular block of 90%. Setpoint deviation, the number of manual interventions and surgeon's complaints were recorded. Drug use and its variability between and within patients were evaluated. Results: Median time of closed-loop control for the 11 patients included in the data processing was 135 [89–336] min (median [range]). Four patients had to be excluded because of sensor problems. Mean absolute deviation from setpoint was 1.8 ± 0.9 T1%. Neither manual interventions nor complaints from the surgeons were recorded. Mean necessary mivacurium infusion rate was 7.0 ± 2.2 μg kg−1 min−1. Intrapatient variability of mean infusion rates over 30-min interval showed high differences up to a factor of 1.8 between highest and lowest requirement in the same patient. Conclusions: Neuromuscular block can precisely be controlled with mivacurium using our model-based controller. The amount of mivacurium needed to maintain T1% at defined constant levels differed largely between and within patients. Closed-loop control seems therefore advantageous to automatically maintain neuromuscular block at constant levels.

Background and objective The intubating laryngeal mask is designed to act as a ventilatory device and as an aid to blind tracheal intubation in adults. The aim of this study was to evaluate the efficacy of the intubating laryngeal mask for ventilation of the lungs and tracheal intubation in children using video-endoscopic control.

Methods The handling and efficacy of the size 3 intubating laryngeal mask for tracheal intubation in 80 children weighing ≥ 25 kg were assessed under video-endoscopic control. Ease of intubating laryngeal mask insertion, adequacy of lung ventilation through the intubating laryngeal mask and airway sealing pressures were recorded. Tracheal intubation was performed blindly by the intubator, while the supervisor observed the procedure on the video display. If blind intubation failed at the first attempt, the monitor view was used to guide the tracheal tube into the trachea. The success rate and time required for successfully placing the tracheal tube were recorded.

Results Insertion of the intubating laryngeal mask was easy in all children. Lung ventilation through the intubating laryngeal mask was uniformly excellent. Blind tracheal intubation at the first attempt was successful in 53 children (66%) within 18.8 ± 4.1 s. Twenty-four of the 27 failed blind intubation attempts were successfully intubated with video-endoscopic guidance within 28.6 ± 9.4 s. Two children required replacing the intubating laryngeal mask, one child had to be intubated conventionally.

Conclusions The size 3 intubating laryngeal mask provides an airway that is easy to establish in children ≥ 25 kg with excellent ventilation conditions and allows blind tracheal intubation at the first attempt with a high success rate. Endoscopic monitoring improves its safety and intubation success rate.

A 36-year-old female presented with seizures and transient dysphasia in her 31 week of pregnancy. Neuro-radiological investigations revealed a large falx meningioma. A decision was taken to deliver the infant and excise the tumour before term because of the risk of an increase in the size of the tumour and the risk of sinus thrombosis. Therefore, she underwent in her 32 week of pregnancy an elective Caesarean section followed by a craniotomy to remove the meningioma. There were no neonatal complications and she made an uneventful recovery. The final pathology report confirmed the diagnosis of meningioma with progesterone positive receptors.

Hypoventilation as a consequence of deep intravenous sedation is the most frequently reported cause of cardiac arrest during upper gastrointestinal endoscopy (UGIE). Haemodynamic stress can contribute to myocardial ischaemia; therefore, this study was designed to observe prospectively the cardio-respiratory changes during UGIE using either midazolam or propofol for conscious sedation. Thirty-four patients, aged 50 years and older, ASA physical status I–III, scheduled for elective UGIE with sedation, were studied. Oxygen saturation, heart rate, non-invasive blood pressure and Holter ECG were recorded continuously starting 15 min before sedation until 15 min after the endoscopy. In addition, plasma catecholamine concentrations were determined. The results of this study are consistent with previous reports that cardiopulmonary events may occur during endoscopy, with or without sedation. Both midazolam and propofol sedation may provide some protection against haemodynamic stress in response to insertion and manipulation of the endoscope, but sedation can also contribute to the occurrence of hypoxaemia.

This study was undertaken to determine the minimum effective dose of granisetron, 5-hydroxytryptamine type 3 receptor antagonist, for the prevention of post-operative vomiting in children undergoing general inhalational anaesthesia for surgery (inguinal hernia and phimosis). In a randomized, double-blind manner, 120 children, ASA physical status I, aged 4–10 years, were assigned to receive placebo (saline) or granisetron at three different doses (20 μg kg−1, 40 μg kg−1, 100 μg kg−1) intravenously immediately after inhalation induction of anaesthesia (n=30 of each). A complete response, defined as no emesis and no need for another rescue antiemetic during the first 24 h after anaesthesia, occurred in 57% with placebo, 67% with granisetron 20 μg kg−1, 90% with granisetron 40 μg kg−1 and 90% with granisetron 100 μg kg−1 respectively (P<0.05; overall Fisher's exact probability test). No clinically important adverse events were observed in any of the groups. Our results suggest that granisetron 40 μg kg−1 is the minimum effective dose for the prevention of emesis after paediatric surgery, and that increasing its dose to 100 μg kg−1 provides no demonstrable benefit.

A double-blind randomized study was performed in 100 patients undergoing thyroidectomy to evaluate the effect of positive therapeutic suggestions made during neurolept-anaesthesia. The classic droperidol-fentanyl-N2O technique was used as these drugs preserve the neurophysiological functions required to process the information in the therapeutic suggestions given during general anaesthesia. Patients in the suggestion group heard positive non-affirmative suggestions during the whole operation. An autoreverse tape player was used. The control group listened to an empty tape. Both groups were comparable with respect to demographic variables, anaesthetic technique, drug dosage, duration of anaesthesia and surgery. Patients in the suggestion group suffered significantly less from post-operative nausea or volumiting (suggestion: 47.2% vs. control: 85.7%) and required less anti-emetic treatment (suggestion: 30.6% vs. control: 68.6%). We conclude that therapeutic suggestions heard during neurolept-anaesthesia are processed and decrease post-operative nausea and vomiting in patients after thyroidectomy.

Good measures for self-report of pain in children are important, particularly as other informants tend to underestimate children's pain. This paper describes the development of a new computer-assisted approach to assessment of pain in children. The child can represent a range of different types of pains on body maps, and use two scales to indicate the size of the pain and the ‘throb’ or intensity. Facial expressions of associated emotions can also be incorporated into the figure. A series of ‘pain pages’ is included in the program. The pages allow changes in pain to be tracked over time, building up a cumulative record. The child can also report on different experiences and give retrospective accounts. Potential applications are suggested, for example in facilitating communication with children who find it difficult to give a clear verbal account of their pain, due to emotional difficulties, language or disability. Research directions are outlined.

Summary

Background and objective: In cases of aspiration of gastric contents the risk of pneumonitis is dependent on the pH and volume of the gastric contents. Omeprazole and rantidine each decrease gastric volume and increase gastric pH. We evaluated the efficacy of preoperative administration of omeprazole (60 mg) or ranitidine (150 mg) in the prophylaxis of aspiration pneumonitis.

Methods: Data were obtained from 75 elective female surgical patients randomly allocated to one of three groups, who received either omeprazole 60 mg orally, or ranitidine 150 mg orally, or neither, on the evening prior to, and on the morning of, surgery. Gastric volume and pH was measured using blind aspiration.

Results: Both pH <2.5 and volume >25 mL were present in none of the patients in either the ranitidine or omeprazole groups, compared to 15 of 25 control patients (P < 0.0001).

Conclusions: Preoperative oral administration of omeprazole (60 mg) or ranitidine (150 mg) reduced residual gastric content volume and increased pH >2.5, possibly reducing the effects of pulmonary aspiration of gastric contents.

Background and objective: Cost consciousness has become increasingly important in anaesthesia as elsewhere in healthcare. Cost-minimization with uncompromised patient safety and quality requires systematic comparisons of alternative techniques. Inhalation anaesthesia with desflurane or sevoflurane is compared in this study with propofol delivered by the target controlled infusion technique. Directly measured drug consumption and costs and emergence times are compared.

Methods: Consumed anaesthetics were measured during elective arthroscopy of the knee, and costs were calculated for ASA I–II patients (n = 102) randomized to 3 groups: one group received anaesthesia using propofol administered by target controlled infusion, the others inhalation anaesthesia with either desflurane or sevoflurane in combination with nitrous oxide. A partial rebreathing system was used with a laryngeal mask airway. Vaporizers were weighed before and after each anaesthetic.

Results: Aaesthetic duration, postoperative pain and emesis as well as discharge time did not differ between groups. Inhaled anaesthetic techniques with desflurane or sevoflurane were associated with 2–3min shorter emergence times (P < 0.001) and approximately 45% lower cost for consumed anaesthetics as compared with propofol technique based on target controlled infusion. The inclusion of waste costs improved the cost reduction to 55%.

Conclusions: For this patient group, use of inhalation anaesthesia reduced drug costs by half and shortened emergence times compared to target controlled infusion with propofol with equal perioperative patient conditions.

Summary

Background and objective: Arterial catheters are routinely used to sample blood for clotting studies in most cardiothoracic intensive care units. The clotting profile in surgical bleeding after cardiac surgery influences further management. Aspiration and discard of a certain amount of blood from the line, prior to sampling, are assumed to clear heparin contamination. We have investigated this assumption through analysis of the clotting profile by simultaneous arterial line and peripheral venous samples.

Methods: The morning following cardiac surgery, simultaneous arterial line and peripheral venous blood samples were taken for activated plasma thromboplastin time (APTT) ratio and international normalized ratio (INR) in 49 randomly selected patients. Also, a thromboelastogram analysis (TEG) (n = 7) was made. A survey of 22 UK cardiothoracic intensive care units was carried out to determine the practice for the withdrawal of blood for clotting studies.

Results: The median arterial APTT ratio value was 1.32 ± 0.52 as compared to the median peripheral APTT ratio value which was 1.1 ± 0.24 (P < 0.001). INR values were statistically similar by both routes. Heparin contamination was confirmed by TEG which revealed that the R-value for arterial catheter blood samples without heparinase in the cup was higher (406.00 ± 64.44 s) compared with the value for arterial samples with heparinase in the cup (318.28 ± 47.26 s, P < 0.05). The survey of 22 UK cardiothoracic intensive care units showed that heparinized arterial lines were by far the commonest ports used for blood withdrawal for the measurement of APTT ratio results.

Conclusions: Samples withdrawn from heparinized arterial lines cannot be relied upon for APTT ratio results.

Summary

Background and objective: The purpose of this prospective randomized study was to assess the value of pressure support ventilation during inhalational induction with sevoflurane in adult patients. Methods: Thirty-five adult patients, ASA I–II and scheduled for ear nose throat surgery were studied. Vital capacity induction with 8% sevoflurane in 8 L min−1 oxygen was performed. Pressure support ventilation was used in Group 1 with pressure set at 15 cmH2O. In Group 2, patients breathed spontaneously. After 2 min, sevoflurane was set to 3% and remifentanil 1 μg kg−1 was injected over 2 min followed by an infusion of 0.1μg kg−1 min−1. Two minutes after the end of the bolus, intubation was performed. Bispectral index, oxygen saturation, respiratory rate, end-tidal carbon dioxide, expired tidal volume and expired sevoflurane concentration were recorded every minute. Results: Eighteen patients were included in Group 1 and 17 in Group 2. Saturation, respiratory rate and end-tidal carbon dioxide were similar in the two groups. Expired tidal volume was significantly higher and bispectral index values significantly lower in Group 1. Intubating conditions were better in Group 1. Conclusions: Pressure support ventilation provides both better ventilation and deeper level of anaesthesia during inhalation induction with sevoflurane.

Background and objective To investigate the ability of lidocaine to inhibit reactive oxygen and/or nitrogen species generation by either human leukocytes or cell-free systems via luminol- and lucigenin-enhanced chemiluminescence.

Methods Venous blood was obtained from healthy volunteers and leukocytes were isolated, from which chemiluminescence was generated. Also, chemiluminescence, induced by H2O2, HOCl, peroxynitrite or ferrous iron, was generated in cell-free systems.

Results Lidocaine produced a concentration-dependent inhibition in chemiluminescence generated by leukocytes (92 ± 1%, 1 mM). In cell-free experiments, lidocaine (1 mM) markedly inhibited chemiluminescence of xanthine-xanthine oxidase (24 ± 3%), while it slightly suppressed hypochlorous acid-induced chemiluminescence (9 ± 2%). Peroxynitrite-induced luminol- and lucigenin-enhanced chemiluminescence were also inhibited by lidocaine at 1 mM (19 ± 3% and 48 ± 8%, respectively). Lidocaine did not affect chemiluminescence generated by FeSO4. However, lidocaine produced a biphasic effect on H2O2-induced chemiluminescence (37 ± 5% inhibition at 0.01 mM and 61 ± 17% activation at 1 mM).

Conclusions Lidocaine can elicit direct scavenging activity at high concentrations that might be important at or near the site of injection in local anaesthetic use.

The effects of inhalational anaesthetic agents on renal sympathetic nerve activity (RSNA) were compared in anaesthetized rabbits. Concentrations of 6% desflurane, 1.2% isoflurane, and 2.4% enflurane increased mean RSNA up to 32, 36 and 44% while higher concentrations, of 12, 2.4 and 3.2% depressed it by 42, 83 and 5%, respectively. For halothane RSNA was unchanged up to 0.8% and decreased by 36% at 1.6% concentration. Nitrous oxide increased RSNA up to 28% at 50% concentration. Maximum reductions in mean arterial pressure (MAP) were 60% for both 2.4% isoflurane and 3.2% enflurane, 50% for 12% desflurane and 1.6% halothane, while 70% nitrous oxide increased MAP by 22%. In conclusion, unlike the entirely depressive effects of halothane, the effects of desflurane, isoflurane and enflurane were biphasic involving excitation at lower concentrations and depression of RSNA and a reduction in MAP at higher concentrations. Nitrous oxide caused increases in both RSNA and MAP.

Mitochondrial myopathies are rare complex multisystem disorders, which can present several potential anaesthetic problems. A 49-year-old man with mitochondrial myopathy was anaesthetized successfully for cataract extraction using propofol and alfentanil infusions. Vecuronium sensitivity was apparent, with a prolonged duration of action, despite dosage reduction

The treatment of tracheo-bronchial diseases with rigid bronchoscopy requires general anaesthesia without tracheal intubation. Spontaneous assisted ventilation is a safe modality of ventilation. In this study the use of remifentanil and fentanyl is compared during rigid bronchoscopy with spontaneous assisted ventilation. Ninety high-risk patients received fentanyl or remifentanil with propofol for general anaesthesia. During the maintenance fentanyl was delivered at 6.1±4.6 μg kg−1 h−1 and remifentanil at 0.15±0.07 μg kg−1min−1. The same degree of intra-operative respiratory acidosis with similar good operating conditions resulted in both groups. Patients treated with remifentanil recovered more quickly compared with those in the fentanyl group (3.8±2 vs. 10.4±9.2 min, P<0.001). In conclusion, the use of remifentanil during rigid bronchoscopy under general anaesthesia with spontaneous assisted ventilation is safe and assures good operating conditions. Moreover, remifentanil permits a more rapid recovery than fentanyl. The dose of remifentanil is higher than previously described for spontaneously breathing patients.

We describe the case of a 36-year-old woman, with a previous history of recurrent abortion due to protein S deficiency, undergoing an elective Caesarean section at 39-weeks gestation. During pregnancy no signs of hypertension or cardiovascular disease were reported, but at the end of the surgical procedure, the patient developed acute hypertension, leading to myocardial infarction, severe heart failure and death. The autopsy revealed a 2-cm undiagnosed phaeochromocytoma in the right adrenal gland. Clinical diagnostic features of phaeochromocytoma during pregnancy as well as the main therapeutic approaches suggested in the literature are discussed.

Summary

Background and objective: Adding various opioids to the local anaesthetic solution administrated intrathecally improves the analgesic potency of spinal analgesia. The purpose of this study was to evaluate the efficacy and safety of intrathecal fentanyl 10 μg added to 15 mg hyperbaric ropivacaine in patients undergoing caesarean section under spinal anaesthesia.

Methods: Thirty-seven healthy, full-term parturients were randomly assigned into two groups: Group S (saline group, n = 17) received 15 mg hyperbaric ropivacaine in 2.5 mL + 0.5 mL saline; Group F (fentanyl group, n = 20) received 15 mg hyperbaric ropivacaine in 2.5 mL + 10 μg fentanyl in 0.5 mL, intrathecally. Characteristics of spinal block, intraoperative quality of spinal anaesthesia, time to first feeling of pain (complete analgesia), time to first request of analgesics postoperatively (effective analgesia), side-effects and fetal outcomes were evaluated.

Results: Regression of sensory block to L5 was significantly prolonged in the fentanyl group compared with the saline group (P = 0.001). Time to the first feeling of pain (130.6 ± 15.8 min vs. 154.3 ± 31.1 min; P = 0.008) and the first analgesic requirement (161.2 ± 32.6 min vs. 213.0 ± 29.3 min; P < 0.001) were significantly shorter in the saline group compared with the fentanyl group. Side-effects, umbilical arterial and venous blood gases did not differ between the groups. Apgar scores were similar in both groups and no infants had an Apgar score ≤7 at 5 min.

Conclusions: The addition of fentanyl 10 μg, to hyperbaric ropivacaine 15 mg, for spinal anaesthesia increased the duration of analgesia in the early postoperative period in patients undergoing caesarean delivery.

Von Hippel-Lindau disease is a rare autosomal dominant disease with incomplete penetrance and variable expression and is characterized by diffuse haemangioblastomas of the central nervous system and viscera. The majority of the central nervous system lesions are located in the cerebellum. This report describes the successful management with epidural anaesthesia of a woman with a term gestation, von Hippel-Lindau disease and cerebellar haemangioblastoma.