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Fifty anaesthetists were recruited to use 20 different laryngoscope blades (one metal re-usable blade, five metal single-use blades and 14 plastic single-use blades, of which eight were bulb-type and 12 were fibreoptic-type) in a manikin to achieve a grade I Cormack and Lehane view. The anaesthetists were asked to provide visual analogue scores (VAS) for: ease of attachment of the blade to the handle; illumination; view of the larynx; and satisfaction for clinical use. The peak force applied and time to achieve the grade I Cormack and Lehane view were also measured. A cluster analysis method was used to group together blades with similar scores or measures.Ease of attachment, illumination, view, clinical use, force and duration were all significantly affected by the blade used (p < 0.0001 for all six). The mean peak force applied and mean duration for the 20 blades were 32–39 N and 4.4–9.5 s, respectively. All five metal single-use and four plastic single-use blades were always placed in the‘best’ group in the cluster analysis. Two plastic blades provided a poor view and increased the duration of laryngoscopy. [ABSTRACT FROM AUTHOR]

The investigation of anaphylactic reactions in the peri-operative period is difficult. Elevation of serum tryptase levels is a good indicator of an anaphylactic event but the ability of subsequent investigations to identify the drug(s) responsible for the reaction is still potentially unreliable. The aim of this study was to examine basophil activation as an investigative tool. We performed flow cytometric analysis of the expression on the cell surface of the basophil activation markers CD63 and CD203c and measured histamine release in 21 patients who were referred with possible peri-operative anaphylaxis. The sensitivity of CD63, CD203c, basophil histamine release and skin prick for the muscle relaxants was found to be 79%, 36%, 36% and 64%, respectively; the specificity was found to be 100%. These results demonstrate the difficulty in investigating the cause of an unexpected clinical event following drug administration, but the higher sensitivity of neo-expression on the cell surface of CD63 suggests that flow cytometric analysis of its neo-expression on basophilsin vitromay be a diagnostic aid. [ABSTRACT FROM AUTHOR]

The article presents abstracts presented at the Association of Anaesthetists of Great Britain and Ireland Annual Congress in Cardiff, Wales, on 21-24 September 2004. Some of the topics on which abstracts were presented are: Illumination provided by single-use laryngoscopes; Distortion of laryngoscope blades under applied force; A comparison of epidural bupivacaine 0.125% and 0.0625% for the management of postoperative pain following major abdominal surgery: a randomised controlled trial; Women's opinions about failure of regional anaesthesia during caesarean section.

A new aza-analogue of furamidine, 6-[5-(4-amidinophenyl)-furan-2-yl]nicotinamidine (DB820), has potent in vitro antitrypanosomal activity; however, it suffers from poor oral activity because of its positively charged amidine groups. The dimethoxyamidine prodrug of DB820, N -methoxy-6-{5-[4-( N -methoxyamidino)phenyl]-furan-2-yl}-nicotinamidine (DB844), has potent oral activity in mouse models of both early-stage and CNS African trypanosomiasis. Metabolism of DB844 in human liver microsomes (HLM) was investigated using liquid chromatography-mass spectrometry (LC-MS/MS). The metabolism of DB844 in HLM was NADPH-dependent and resulted in the production of eight metabolites over a 90?min incubation. O -Demethylation and N -dehydroxylation reactions resulted in the metabolic conversion of DB844 to its active DB820 metabolite. Chromatographic conditions used for LC-MS analysis allowed for the separation and identification of all metabolites including positional isomers. Demethylation of either the phenyl or pyridine side of DB844 (DB844 m / z 366.2) resulted in the production of two metabolites (M1A, M1B), each with a molecular ion of m / z of 352.3 and MS 2 fragments of 288.1, 305.2, 321.2 and 335.2. However, the intensities of the MS 2 fragments were different among the two isomeric metabolites, and comparison to an authentic standard allowed for the structural determination of each metabolite. The isomeric metabolites M2A and M2B, resulting from amidoxime reductions of M1A and M1B, were also chromatographically separated and had distinguishable MS 2 profiles that allowed for their structural assignments when compared to an authentic standard. The di-amidoxime product resulting from O -demethylation of either side of DB844 was also identified as an abundant metabolite during microsomal incubations. The active antitrypanosomal metabolite, DB820, was the last metabolite to be formed and thus provides evidence that DB844 may effectively be metabolized to its active metabolite in vivo . [ABSTRACT FROM AUTHOR]

The Cardiff paediatric laryngoscope blade is a single blade that has been designed for use in children from birth to adolescence. This open, randomised, crossover study compared the Cardiff blade with the straight, size 1, Miller laryngoscope blade in 39 infants under 1 years of age and the curved, size 2, Macintosh blade in 39 children aged 1–16 years. The same laryngoscopic view was obtained with the Cardiff and Miller blades in 26 patients; the view was better with the Cardiff blade in seven patients and better with the Miller blade in six (median (IQR[range]) grade of laryngoscopy 1 (1–2[1–3]) vs. 1 (1–2[1–3]), respectively; p = 0.405). The Cardiff blade was faster at gaining a view than the Miller blade (mean (SD) time 8.5 (2.9) s vs. 10.2 (3.5) s, respectively; 95% CI for difference−2.8 to−0.4; p = 0.009). The Cardiff and Macintosh blades produced the same view in 32 patients; the view was better with the Cardiff blade in seven patients (median (IQR[range]) grade of laryngoscopy 1 (1–1[1–3]) vs. 1 (1–2[1–3]), respectively; p = 0.008). There was no difference in time to gain these views: mean (SD) 8.7 (3.0) s vs. 9.3 (2.7) s, respectively (95% CI for difference−1.58 to 0.40; p = 0.237). The Cardiff paediatric laryngoscope blade compares favourably with these two established laryngoscope blades in children. [ABSTRACT FROM AUTHOR]

In a randomised cross-over study, 48 anaesthetists attempted to place a Frova single-use introducer, an Eschmann multiple-use introducer and a Portex single-use introducer in the trachea of a manikin set up to simulate a grade 3 laryngoscopic view. The anaesthetists were blinded to success (tracheal placement) or failure (oesophageal placement). Successful placement (proportion, 95% confidence interval) of either the Frova introducer (65%, 50–77%) or the Eschmann introducer (60%, 46–73%) was significantly more likely than with the Portex introducer (8%, 3–20%). There were no significant differences between the success rates for the Frova and the Eschmann introducers. A separate experiment revealed that the peak force exerted by the Frova and Portex introducers was two to three times greater than that which could be exerted by the Eschmann introducer, p < 0.0001, indicating that the single-use introducers are more likely to cause tissue trauma during placement. [ABSTRACT FROM AUTHOR]

Summary The concern that re-usable equipment may be a source of cross-infection has prompted the increased use of disposable laryngoscope blades. We conducted a study investigating the duration of laryngoscopy and the peak force generated using various laryngoscope blades. Five blades were studied: one reusable Macintosh 3 blade, one disposable metal blade and three plastic disposable blades. Sixty anaesthetists performed laryngoscopy on a mannequin using each of the five blades presented in a random order. This was then repeated with a rigid collar applied to the mannequin. The mean force applied with the collar off with the metal blades was 32.8 and 30.8 N, and with the plastic blades 37.3, 39.6 and 41.5 N, respectively (p < 0.0001). The mean force applied with the collar on with the metal blades was 30.5 and 32.5 N, and with the plastic blades 35.5, 34.9 and 31.4 N, respectively (p < 0.0001). The mean duration of laryngoscopy with the collar off for the metal blades was 5.6 and 5.4 s, and with the plastic blades 10, 7.2 and 7.5 s (p < 0.0001). The duration of laryngoscopy with the collar applied for the metal blades was 7.1 and 7.5 s, and with the plastic blades 11.8, 9.7 and 9.0 s (p < 0.0001). The use of plastic blades results in both greater peak force and duration of laryngoscopy. [ABSTRACT FROM AUTHOR]

We examined the use of the 30 degrees rigid nasendoscope in aiding difficult tracheal intubations. A Cormack and Lehane grade 4 difficult intubation (no view of glottis or epiglottis) was set up on a manikin. After 10 s of tuition, 40 anaesthetists attempted to pass a standard gum elastic bougie between the cords, with and without the nasendoscope, in randomised order. A bougie curved to an 'optimal curve' was also tested. Using the standard bougie 13/40 (33%) passed the bougie between the cords without the nasendoscope, compared with 31/40 (78%) when using the nasendoscope (p < 0.001). The 'optimal curve' bougie resulted in 29/40 (73%) and 39/40 (98%) success rates without and with the nasendoscope, respectively (p = 0.004). The nasendoscope is a simple and easy to use tool in grade 4 intubation, and results are improved further by the use of an 'optimal curve' bougie. [ABSTRACT FROM AUTHOR]

Paediatric anaesthetists are at higher risk of exposure to waste anaesthetic gases, which often exceed set safety limits. Recommended personal diffusive sampling techniques for monitoring exposure to waste anaesthetic gases may not give a true profile of exposure and hence biological sampling may also be necessary. We evaluated the exposure of paediatric anaesthetists to nitrous oxide and sevoflurane as assessed by personal environmental and biological samples. The influence of venue and technique, and the strength of the relationship among the various sampling techniques were analysed. The study found that exposure to nitrous oxide during paediatric anaesthetic inductions is still a major problem, although exposure to sevoflurane was usually within the accepted limits. The type of breathing system used and the presence of scavenging seem to influence this exposure, though surprisingly, the induction technique or the methods of airway control do not. No significant relationship was found between the various biological indicators measured. [ABSTRACT FROM AUTHOR]

Summary We evaluated the modified Airway Management Device (AMDTM ) in 60 spontaneously breathing anaesthetised patients. The insertion and removal of the device was very easy and atraumatic. The airway was secured on the first attempt in 41 patients (70%; 95% CI 57–80%). The most important problem was loss of airway, which occurred in 11 patients (19%; 11–30%) during maintenance of anaesthesia. The AMD was dislodged during maintenance in one patient. There was a loss of the airway in 12 patients (20%; 12–31%); in 10, it was maintained with simple airway manoeuvres or a laryngeal mask airway and tracheal intubation was required in two patients. Ten of these patients were male and two were female; the failure rate was 33% (12–31%) among the male patients and 6% (2–22%) among the female patients. The cuff volumes ranged from 4 ml to 80 ml and cuff pressures from 6 cm H2 O to 92 cm H2 O. Blood was seen on removal in three patients (6%; 2–16%) and nine patients (18%; 10–30%) experienced sore throat after removal of the device. [ABSTRACT FROM AUTHOR]

Twelve volunteers known to have airways that responded adversely to 2.0 MAC desflurane were recruited. Each volunteer inhaled three single breaths of each of 0.5, 1.0 and 2.0 MAC of sevoflurane, halothane, isoflurane, desflurane and balance air, with breaths of air between, whilst breathing nasally through a face mask attached to one of three filters that provided three different levels of humidification. The incidence of any adverse airway events was recorded. The anaesthetic inhaled significantly affected the incidence of adverse airway events (p < 0.001), with the least to most irritant being sevoflurane, halothane, isoflurane and desflurane. Increasing the concentration of anaesthetic also significantly increased the incidence of adverse airway events (p < 0.001). The filter used, and hence the level of humidification, did not affect the incidence of adverse airway events (p = 0.09), but repeated exposure caused a significant reduction in the incidence of adverse airway events (p < 0.001). [ABSTRACT FROM AUTHOR]

Summary Where practicable, exposure to a hazardous substance should be eliminated or adequately controlled. A postal questionnaire survey was sent to 10% of consultants from the Association of Anaesthetists of Great Britain and Ireland, to identify the level of use of nitrous oxide in current anaesthetic practice and identify any change of practice over the last 5 years. Details of anaesthetic practice were requested in three areas: nitrous oxide usage, availability of medical air on anaesthetic machines and the use of total intravenous anaesthesia. Replies were received from 320 consultants (75%). Of these, 49% felt that, over the last 5 years, their use of nitrous oxide had decreased. Twenty per cent of anaesthetists felt that there should be some restriction in availability of nitrous oxide. Where medical air was available, 32% felt that they would use it frequently. A total of 263 (83%) stated that they use total intravenous anaesthesia to some extent. The results showed that, although 49% of consultant anaesthetists had reduced their use of nitrous oxide, this was due to medical considerations rather than concerns over health and pollution issues arising from the use of nitrous oxide. [ABSTRACT FROM AUTHOR]

Summary Accidental oesophageal intubation is still an important cause of anaesthetic morbidity and mortality. This study investigated the use of impedance respirometry to determine the position of a tracheal tube. Seventy-nine patients undergoing general anaesthesia requiring tracheal intubation with muscle relaxation were recruited to the study. After pre-oxygenation, tracheal tubes were placed in both the oesophagus and trachea; a breathing system was attached to one tube chosen randomly. A blinded observer was required to correctly identify the position of the tube within six tidal ventilations. The position of every tube connected to the breathing system was correctly identified. The median time to correctly identify tracheal and oesophageal tubes was 3 and 5 s, respectively. The median number of breaths to identify tracheal and oesophageal tubes was two for both groups. Every tube position was identified within the required six breaths. Impedance respirometry is a reliable method for diagnosing tracheal tube position. [ABSTRACT FROM AUTHOR]

Background: Hypothalamic amenorrhoea (HA) is a syndrome associated with infertility and osteopenia in reproductive-age women.Methods: To understand better the natural history of this disorder, 28 women participated in a retrospective, questionnaire-based analysis to elucidate factors associated with spontaneous recovery.Results: 54% of subjects developed HA related to an eating disorder, 21% related to stress +/- weight loss, and 25% without obvious contributing factors (idiopathic). HA associated with a clear precipitant had a better prognosis than idiopathic HA (71 versus 29% recovery; P < 0.05). Reversal of the inciting factor appeared necessary but not sufficient for recovery (83% recovery if factor reversed). Normal menarche occurred in 61% of subjects, oligomenorrhoea in 32%, and primary amenorrhoea in 7%. Oligomenorrhoea and normal menarche showed a trend toward better prognosis than primary amenorrhoea (NS). Compared with controls, 46% of HA patients had decreased frequency of LH pulses, 7% decreased amplitude, 18% decreases in both frequency and amplitude, 18% absent pulses, and 11% normal-appearing pulses. Pulse pattern at baseline did not predict recovery.Conclusions: The aetiology of HA at the time of presentation predicts subsequent recovery of menstrual function. In stress, weight loss, or eating disorder-related HA, rates of recovery exceeded 80% when precipitating factors were reversed. Idiopathic HA may represent a different disorder as recovery rates were <30%. [ABSTRACT FROM AUTHOR]

The effect of two levels of humidification on the incidence of adverse airway events was studied in 58 adult female patients during deepening of anaesthesia using up to 12% desflurane. Humidification was provided by a breathing system filter with either low moisture-conserving performance (17.2 mg.l-1 at 0.5 l tidal volume, Group L) or high moisture-conserving performance (33.5 mg.l-1 at 0.5 l tidal volume, Group H). Forty-eight per cent of patients smoked and there were more smokers in Group L than in Group H. Adverse airway events consisted of coughing and laryngospasm. For coughing, the dominant explanator was smoking. When both humidity and age were included in the analysis, there was a significant smoking–humidity interaction (p < 0.05), such that high humidity decreased the incidence of coughing in nonsmokers but not in smokers. The incidence of laryngospasm was significantly lower in Group H than in Group L (p < 0.05). We conclude that when patients inspire high concentrations of desflurane during induction of anaesthesia, increasing humidification to the levels achieved in this study decreases the incidence of coughing among nonsmokers and of laryngospasm in both smokers and nonsmokers. [ABSTRACT FROM AUTHOR]

Several methods are available to measure splanchnic blood flow and gut ischaemia. Tonometry is most practical for peri-operative use. Epidural blockade from T5 to T11 causes mesenteric arteriovenous vasodilation and may increase splanchnic blood flow. This study assesses the ability of tonometry to measure differential effects of opiate and epidural analgesia on splanchnic blood flow. Forty patients for elective colorectal surgery were randomly allocated to receive epidural infusion or intravenous morphine. Gastric mucosal Pco2, pHi, standard pHi, Pco2 gap and pH gap were measured after induction and on termination of surgery. These parameters were within normal limits at the end in most cases and there was no significant difference between the groups. The complication rate was similar in both groups and was not correlated with low pHi, but was correlated with blood loss. We were unable to demonstrate a difference in splanchnic perfusion, as assessed by gastric tonometry, between the two groups. [ABSTRACT FROM AUTHOR]

Examines the second stage of anaesthesia during sevolflurane induction to see if any shortening of its duration was at the expense of different sympathetic mechanisms. Blood pressure, heart rate and sympathetic nerve responses; Characterization of the stages of sympathetic activity; Percentage of sevoflurane induction that produced a shorter second stage.

Sevoflurane induction of anasthesia has been examined extensively, but little is known about the usefulness of other drugs as adjuncts to hasten and smooth the process. Sixty patients, undergoing surgery of a type suitable for a spontaneous respiration, laryngeal mask airway anasthetic technique, were randomly allocated to receive 1.0 microgram.kg-1 intravenous fentanyl or the equivalent volume of normal saline, 30 s prior to triple-breath induction with sevoflurane. The study was double-blind. There were no differences between the groups for the times to loss of eyelash reflex, jaw relaxation, insertion of the laryngeal mask airway or regular settled breathing. However, there was a difference in the incidence of adverse airway events (breath-holding, coughing and laryngospasm) between the two groups (16.5% in the fentanyl group and 40% in the placebo group); this did not reach statistical significance. Both groups were haemodynamically stable throughout induction, although the fentanyl group had a statistically significant decrease in systolic blood pressure at 4 min compared with the placebo group, which was not considered clinically relevant. We conclude that fentanyl has no significant influence over the speed and quality of sevoflurane induction. [ABSTRACT FROM AUTHOR]

The Xenopus laevis oocyte is widely used to express exogenous channels and transporters and is well suited for functional measurements including currents, electrolyte and nonelectrolyte fluxes, water permeability and even enzymatic activity. It is difficult, however, to transform functional measurements recorded in whole oocytes into the capacity of a single channel or transporter because their number often cannot be estimated accurately. We describe here a method of estimating the number of exogenously expressed channels and transporters inserted in the plasma membrane of oocytes. The method is based on the facts that the P (protoplasmic) face in water-injected control oocytes exhibit an extremely low density of endogenous particles (212 +/- 48 particles/microns2, mean, SD) and that exogenously expressed channels and transporters increased the density of particles (up to 5,000/microns2) only on the P face. The utility and generality of the method were demonstrated by estimating the "gating charge" per particle of the Na+/glucose cotransporter (SGLT1) and a nonconducting mutant of the Shaker K+ channel proteins, and the single molecule water permeability of CHIP (Channel-like In-tramembrane Protein) and MIP (Major Intrinsic Protein). We estimated a "gating charge" of approximately 3.5 electronic charges for SGLT1 and approximately 9 for the mutant Shaker K+ channel from the ratio of Qmax to density of particles measured on the same oocytes. The "gating charges" were 3-fold larger than the "effective valences" calculated by fitting a Boltzmann equation to the same charge transfer data suggesting that the charge movement in the channel and cotransporter occur in several steps. Single molecule water permeabilities (pfs) of 1.4 x 10(-14) cm3/sec for CHIP and of 1.5 x 10(-16) cm3/sec for MIP were estimated from the ratio of the whole-oocyte water permeability (Pf) to the density of particles. Therefore, MIP is a water transporter in oocytes, albeit approximately 100-fold less effective than CHIP. [ABSTRACT FROM AUTHOR]

Ion channels are believed to play an important role in the maintenance of lens transparency. In order to ascribe junctional and nonjunctional permeability properties to specific lens cell types, embryonic chick lenses were enzymatically dissociated into cell clusters, cell pairs and single cells, and both cell-to-cell and single-membrane permeability properties were characterized with the patch-clamp technique. Double patch-clamp experiments and single patch-clamp experiments with Lucifer yellow in the pipette demonstrated that the cells in the dissociated preparation were well coupled, the average conductance between pairs being 42 +/- 27 nS. Double patch-clamp experiments also revealed single cell-to-cell channel events with a predominant unitary conductance of 286 +/- 38 pS. Whole-cell measurements of surface membrane conductance indicate heterogeneity within the population of dissociated embryonic chick lens cells: 63% of the cells have a voltage-independent leak current, 14% of the cells have a potassium-selective inward-rectifier current, and 23% of the cells have a current which turns off with positive voltage on a time scale on the order of seconds. The time constant for this turnoff is voltage dependent. [ABSTRACT FROM AUTHOR]

Major intrinsic polypeptide (MIP), a 28-kDa protein isolated from lens fiber cell membranes, forms large, nonselective channels when reconstituted into lipid bilayers. MIP channels are regulated by voltage, such that these channels close when the potential across the membrane is greater than 30 mV. We have investigated the modulation of the voltage-dependent closure of MIP channels by phosphorylation. In this report, we describe the isolation of two isomers of MIP from lens fiber cell membranes. These isomers differ by a single phosphate at a protein kinase A phosphorylation site. The phosphorylated isomer produces channels that close in response to applied voltages when reconstituted into bilayers. The nonphosphorylated isomer produces voltage-independent channels. Direct phosphorylation with protein kinase A converts voltage-independent channels to voltage-dependent channels in situ. Analyses of macroscopic and single-channel currents suggest that phosphorylation increases the voltage-dependent closure of MIP channels by increasing closed channel lifetimes and the rate of channel closure following the application of voltage. [ABSTRACT FROM AUTHOR]