This aim of this study was to determine the effect of anaesthetic agents on stapedius reflex (SR) thresholds and transient evoked otoacoustic emissions (TEOAE). Fifty patients who were scheduled for operation and who had normal hearing were included in the study. All were given midazolam for premedication and propofol for induction. Anaesthesia was maintained in five different ways in each group of 10 patients. Groups I–IV received inhalational anaesthesia: group I received 70 per cent N2O plus 30 per cent O2, group II sevoflurane, group III desflurane and group IV halothane. Group V received total intravenous anaesthesia with propofol plus sufentanil. The SR and TEOAE of the patients were measured four times: on the day before surgery (first measurement), after premedication (second measurement), after induction of anaesthesia (third measurement) and during maintenance of anaesthesia (fourth measurement). Midazolam significantly increased ipsilateral and contralateral SR thresholds and decreased TEOAE wave reproducibility. Propofol significantly increased only the SR thresholds. The other anaesthetic agents significantly increased only the contralateral reflex thresholds. Of these, the highest increase was seen after sevoflurane and the lowest after halothane. The changes in TEOAE wave reproducibility due to anaesthetic agents used for maintenance were not significant. We concluded that midazolam premedication may affect audiological evaluation with SR and TEOAE tests, and sevoflurane should not be used when it is necessary to measure SR under general anaesthesia.

Real-time ultrasound data of backfat thickness, longissimus muscle depth and longissimus area were carried out on 335 pigs (164 gilts and 171 barrows) using the Pie Medical Scanner 200 equipped with an ASP-18 probe and 3·5 MHz to predict carcass lean content in positive stress Pietrain (TT) and negative stress Pietrain (CC or CT). They were given food ad libitum and slaughtered at an average age of 213 days and an average weight of 101 kg. The day before slaughter, longitudinal and transverse images were taken at the last rib. After slaughter, the lean meat content was estimated by a CGM (capteur gras-maigre) equipped with an 8-mm diameter Sydel probe. The carcass lean proportion was higher in homozygote TT than homozygote CC and heterozygote CT individuals (P < 0·05). Gilts had more lean meat than barrows (P < 0·05). The correlation between the lean meat proportion and ultrasound backfat thickness (UBFT) or ultrasound longissimus muscle depth (ULMD) respectively was moderate. The prediction of lean meat proportion using UBFT, ULMD and ULMA gave an R2 which varied from 0·35 to 0·79. Real-time ultrasound is a tool that could potentially be used to predict the composition of pig carcasses before slaughter particularly if measurements can be taken with a higher degree of accuracy than at present.

Both the numbers of children undergoing day case surgery and the type of procedures performed in this way are increasing. This expansion will only be beneficial if anaesthesia and surgery are provided with minimal postoperative morbidity e.g. postoperative delirium or nausea and vomiting. The choice of anaesthetic technique is considered critical to optimizing the service provided to patients and for this reason much research has addressed this question. This review considers the effect of anaesthetic technique on postoperative outcome in paediatric day case surgery. The outcome measures reviewed by this article are induction of anaesthesia, effects on the cardiovascular system, recovery from anaesthesia and postoperative nausea and vomiting. In each section both quantitative and qualitative outcome measures are discussed. Comparisons are made between sevoflurane and halothane, sevoflurane and propofol, propofol and halothane, desflurane and halothane and the presence or absence of nitrous oxide.

Malignant hyperthermia is an autosomal-dominant inherited disorder of the skeletal muscle cell characterized by a hypermetabolic response to all commonly used inhalational anaesthetics and depolarizing muscle relaxants. The clinical syndrome includes muscle rigidity, hypercapnia, tachycardia and myoglobinuria as result of increased carbon dioxide production, oxygen consumption and muscle membrane breakdown. In human beings and animals susceptible to malignant hyperthermia, it is generally accepted that an increase in the level of myoplasmic free calcium is the cause of the syndrome. Various hypotheses have been proposed to account for the increase of intracellular calcium levels, e.g. a defect in the calcium release channel of the sarcoplasmic reticulum (ryanodine receptor), an abnormality of the excitation-contraction coupling mechanisms, or alterations in second messenger systems of skeletal muscles. This review gives an overview of the main features of this disease and recent advances in research including pathophysiology, treatment, diagnosis and genetics as well as association with other disorders.

Background and objective Volatile anaesthetic effects on altering tone after blocking nitric oxide synthase, cyclo-oxygenase-prostaglandin synthase and KATP channel pathways are controversial. We examined in isolated guinea pig hearts whether anaesthetics alter bradykinin and 5-hydroxytryptamine-induced effects on coronary flow and percentage oxygen extraction after blocking these pathways.

Methods Before and during exposure to sevo-flurane, halothane or isoflurane, hearts were infused with 10−13–10−8 M bradykinin, or 10−8–10−6 M 5-hydroxytryptamine (serotonin), with either L-NAME, indomethacin, or glibenclamide. Bradykinin or 5-hydroxytryptamine alone increased flow and decreased percentage oxygen extraction in a concentration-dependent manner; these effects were largely blocked by L-NAME (nitro-L-arginine methylester), which also decreased basal flow and increased basal percentage oxygen extraction.

Results The anaesthetics restored bradykinin and 5-hydroxytryptamine-induced increases in flow or decreases in percentage oxygen extraction after inhibition by L-NAME. Indomethacin or glibenclamide alone had little effect on basal flow and percentage oxygen extraction. The anaesthetics restored bradykinin and 5-hydroxytryptamine-induced increases in flow or decreases in percentage oxygen extraction after inhibition by L-NAME. Indomethacin or glibenclamide alone had little effect on basal flow and percentage oxygen extraction. Drug-induced increases in flow and decreases in percentage oxygen extraction in the absence or presence of glibenclamide or indomethacin were not altered at either of the two concentrations of anaesthetics.

Conclusions Endothelium-dependent vasodilatation is not affected by blocking prostaglandin release or KATP channels in the intact heart even in the presence of an anaesthetic. However, the diminished responses to vasodilators after nitric oxide synthase inhibition is largely restored or enhanced by anaesthetics.

Despite a plethora of findings associated with the pathophysiology of malignant hyperthermia (MH), the in vitro contracture test (IVCT) is the only reliable test for diagnosis of this heterogeneous syndrome in man. An increase of 1,4,5-IP3 (inositol 1,4,5-trisphosphate), a second messenger involved in cellular calcium homeostasis, has been observed in muscle tissue of MH susceptible (MHS) patients. The aim of this study was to evaluate if the known differences of 1,4,5-IP3 content in muscle tissue might be reproduced in mononucleated white blood cells (MWBCs). Subsequently, MWBCs of 23 healthy controls and 12 patients with a clinical suspicion for MH disposition were isolated and screened for 1,4,5-IP3 content. An IVCT according to the protocol of the European Malignant Hyperpyrexia Group (EMHG) was performed on muscle specimens of 12 patients. Eight MHN and four MHS individuals were diagnosed. Additionally, 1,4,5-IP3 synthesis in MWBCs was detected following in vitro exposure to IVCT test substances halothane (2%), caffeine (1–30 mM), and ryanodine (1–5 μM). A broad inter-individual variability of 1,4,5-IP3 content was observed in MWBCs of all volunteers, but no differences were detected between MHS and MHN individuals. These findings are in strong contrast to those observed in muscle tissue. In vitro exposure of isolated MWBCs to halothane, caffeine and ryanodine yielded no statistically significant differences between groups. A time and concentration-dependent increase in cellular 1,4,5-IP3 content could be induced in some but not all individuals of both groups. Since no correlation was obtained between induction of 1,4,5-IP3-synthesis following in vitro exposure of MWBCs to MH test substances and MH disposition, this study was terminated. We conclude from our data that the detection of 1,4,5-IP3 synthesis in MWBCs is not suitable for diagnosis of MH disposition. It remains questionable whether an altered 1,4,5-IP3 metabolism in MWBCs is involved in pathologic cascades of MH. Therefore, other cell tissues should be evaluated in further studies to clarify the role of the 1,4,5-IP3 metabolism in MH.

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.

Forty-two children (aged 27–16 years) were randomly assigned to receive either sevoflurane (n=21) or halothane (n=21) in nitrous oxide/oxygen. After premedication with midazolam, anaesthesia was induced by facemask and the anaesthetic concentration was increased until loss of eyelash reflex (sevoflurane, 6%; halothane, 2.5%). Thereafter, 1–1.5 MAC of the inhalational agents were maintained until skin closure. Intra-operative analgesia was provided either by intermittent intravenous (i.v.) bolus doses of fentanyl (2–3 μg kg−1) or by a regional blockade. Induction was smooth and the time to loss of eyelash reflex was slightly shorter with sevoflurane than with halothane, the difference not quite reaching statistical significance (P=0.06). In both groups, heart rate remained stable and blood pressure decreased significantly during induction. Haemodynamic parameters remained stable during anaesthetic maintenance; no cardiac dysrhythmias were observed. Emergence time with sevoflurane was 12.9 min vs. 16.3 min with halothane, but this difference was not statistically significant. It is concluded that sevoflurane is as suitable for paediatric patients as halothane. The slightly faster emergence time offered by sevoflurane over halothane was of no clinical significance in the present study.

A double-blind and randomized study design was used to investigate 100 healthy children, aged 1–5 years. Intubating conditions and cardiovascular changes duraning deep halothane anaesthesia, defined as an endtidal concentration of 2%, were compared with those changes during 1% halothane and suxamethonium relaxation. Intubating conditions were graded according to the ease of laryngoscopy, vocal cord position, coughing and jaw relaxation. In each group 96% of the children demonstrated acceptable intubating conditions. Jaw relaxation was worse in the 1% halothane/-suxamethonium group (P < 0.01). When anaesthesia with 2% or 1% halothane was compared there was a more pronounced decrease in systolic blood pressure (18 vs. 8%, (P < 0.001). Junctional rhythm occured more frequently during deep halothane anaesthesia (46 vs.18%, (P < 0.01). Intravenously (i.v.) administered atropine attenuated blood pressure depression significantly and reinstituted sinus rhythm in most cases.

The changes in heart rate and arterial blood pressure following the administration of suxamethonium in healthy children (mean age 3.8 ± 0.3 years) during inhalational induction with either sevoflurane (n = 22) or halothane (n = 19) were studied. Heart rate 60 s following suxamethonium administration increased significantly in the sevoflurane but not in the halothane group. In the halothane group, four children required intravenous (i.v.) atropine as a result of bradycardia. None of the children in the sevoflurane group developed bradycardia following suxamethonium (P < 0.05). Values of oxygenation, ventilation and age corrected minimal alveolar concentration were comparable at all measurement times. The haemodynamic response to the administration of suxamethonium in children anaesthetized with sevoflurane seems to reflect the stimulation of the autonomic ganglia by suxamethonium whereas this positive chronotropic effect is attenuated or reversed by halothane.

The present study was designed to determine the direct effects of halothane, isoflurane and sevoflurane on the bovine epicardial coronary artery as well as their mode of action. We chose serotonin as the vasoconstrictor because it also causes endothelium-dependent relaxation of coronary arteries. Isolated spiral strips of bovine epicardial coronary artery with and without endothelium were suspended for isotonic contraction recordings in Tyrode's solution. KCl (80.4 mm) solution induced maximal contraction, regarded as the reference value (100%). The muscle strips were then exposed to increasing concentrations of serotonin from 10−8 to 10−4 m in the presence and absence of 1.5 MAC halothane, isoflurane or sevoflurane. All three drugs attenuated serotonin-evoked contraction in the coronary artery strips both those strips with and without endothelium (P < 0.05−0.001). However, there were no significant differences in the attenuation of serotonin-induced contraction of the strips, both with and without endothelium, in each drug group. The attenuation potency of halothane was more than that of isoflurane and sevoflurane. The results demonstrate that halothane, isoflurane and sevoflurane attenuate contractile responses evoked by serotonin in bovine epicardial coronary artery both with and without endothelium.

In order to investigate the antagonism between meat quantity and quality, halothane-positive (HP) and -negative (HN) Belgian Landrace pigs (B) and Pietrain × Belgian Landrace crosses (PB) were compared for several carcass and meat quality traits. They originated from three commercial farms and were slaughtered in a commercial abattoir. Carcass quality was determined by a SKGlI-device. Meat quality traits were measured on the warm and cold carcass, and on a loin slice. HP and PB pigs showed better carcass quality, and inferior meat quality, compared with HN and B pigs respectively. No significant halothane sensitivity × breed interaction was apparent for most traits. Sex did not affect meat quality. Slaughter day variance was considerable. The inverse relationship between lean content or conformation score and meat quality was generally more pronounced in the HP group compared to the HN group (except for drip and cooking losses). Irrespective of halothane status, carcass conformational score was more negatively related to meat quality than was lean content.