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Biomedical subjects

J E Hall

Publications and source records attributed to J E Hall.

At least 37 records · Page 2Linked to original sources
PubMed2005

A comparison of 20 laryngoscope blades using an intubating manikin: visual analogue scores and forces exerted during laryngoscopy.

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.

Cluster Analysis↗
PubMed2005

Flow cytometric investigation of peri-anaesthetic anaphylaxis using CD63 and CD203c.

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 basophils in vitro may be a diagnostic aid.

Anaphylaxis↗
PubMed2005

A comparison of direct laryngoscopy and jaw thrust to aid fibreoptic intubation.

We compared two manoeuvres, jaw thrust and laryngoscopy, to open the airway during fibreoptic intubation in 50 patients after induction of anaesthesia in a crossover study. Patients were randomly allocated to receive either jaw thrust or conventional Macintosh laryngoscopy first. Airway clearance was assessed at both the soft palate and the epiglottis. Direct laryngoscopy provided significantly better airway clearance at the level of the soft palate than jaw thrust (44 (88%) vs 31 (62%), respectively; p = 0.002). At the level of the larynx, airway clearance was equally good in both groups (45 (90%) vs 46 (92%), respectively; p = 0.56). The times to view the larynx (median (interquartile range [range]) 4 (3-5 [2-35]) s vs 3 (3-4 [2-8]) s, respectively) and intubation time (20 (17-23 [11-83]) s vs 18 (15-20 [11-28]) s, respectively) were also similar.

Adult↗
PubMed2005

A comparison of 0.2 and 0.5 mg intrathecal morphine for postoperative analgesia after total knee replacement.

The optimal dose of intrathecal morphine for postoperative analgesia after major surgery is a matter of debate, with some uncertainty concerning the therapeutic potential and safety of intrathecal morphine in the dose range 0.3-1.0 mg. This randomised double-blind study compared the efficacy and side-effect profile of 0.2 mg and 0.5 mg intrathecal morphine in 70 patients undergoing knee replacement surgery. The primary endpoint was the number of patients requiring rescue analgesia (tramadol) during the first 24 h postoperatively. Secondary endpoints included consumption of tramadol and the incidence of adverse effects. Fewer patients in the 0.5-mg group required rescue analgesia in the first 24 h than in the 0.2-mg group (16 (48%) vs 28 (85%), respectively; p = 0.003). Median (IQR [range]) tramadol consumption was lower in the 0.5-mg group than in the 0.2-mg group (0 (0-100 [0-350]) mg vs 100 (50-100 [0-350]) mg, respectively; p = 0.02). The incidence of adverse effects was similar in both groups. This study has demonstrated that 0.5 mg intrathecal morphine produces better analgesia than 0.2 mg after knee replacement without any increase in side-effects.

Adult↗
PubMed2005

Airway management before, during and after extubation: a survey of practice in the United Kingdom and Ireland.

Summary Complications at extubation remain an important risk factor in anaesthesia. A postal survey was conducted on extubation practice amongst consultant anaesthetists in the United Kingdom and Ireland. The use of short acting drugs encourages anaesthetists to extubate the trachea at lighter levels of anaesthesia. The results show that oxygen (100%) is not routinely administered either before extubation or en route to the recovery area. A trend towards a head up or sitting position at extubation is emerging. However, further research into the use of these positions is required. Airway related complications at extubation are relatively frequent but are usually dealt with by simple basic measures. The role of drugs such as propofol in decreasing the incidence of these complications needs further evaluation. Some of these results give concern for patient safety and for training. The importance of teaching and adherence to continued oxygenation until complete recovery is strongly emphasised. Nerve stimulators should be used continually as standard monitoring throughout the anaesthetic period when muscle-relaxing drugs are part of the anaesthetic technique.

Anesthesia, General↗
PubMed2005

Effect of breathing low concentrations of volatile anaesthetic agents on incidence of adverse airway events.

The effect of breathing 0.1 minimum alveolar concentrations (MAC) of desflurane or isoflurane for three minutes on the incidence of adverse airway events on a subsequent breath of 2 MAC was investigated. Twenty-five volunteers known to develop an adverse airway event to desflurane or isoflurane took part in the study. Each volunteer was exposed to isoflurane and desflurane at least 24 h apart. Volunteers were assessed for adverse airway events while breathing 2 MAC inhalational anaesthetic following breathing 100% O(2) for 3 min. This was repeated with 0.1 MAC inhalational anaesthetic in oxygen instead of 100% O(2). Adverse airway events decreased from 88% to 40% when tests were conducted with desflurane (p = 0.002). With isoflurane, the reduction from 60% to 52% was not statistically significant (p = 0.774). Breathing low concentrations of desflurane decreases the incidence of adverse airway events on subsequent inhalation of higher concentration of desflurane.

Adult↗
PubMed2005

Histamine release during adult cardiopulmonary bypass.

Histamine, an inflammatory mediator in its own right, may also be a marker for a more widespread systemic inflammatory process. In this study we have examined variations in plasma histamine concentrations produced during the course of cardiac surgery involving cardiopulmonary bypass, the relationship between these variations and intra-operative events. By assays of serum tryptase and CD-63 expression we have also attempted to identify the source of histamine. Histamine concentrations that were significantly raised from baseline level were demonstrated. These were elevated from the time of aortic cross-clamping and continued to be raised for 24 h postoperatively (p < 0.00625). This was associated with an increase in CD-63 expression (p < 0.025) (but not an increase in tryptase concentration) following aortic cross-clamping and protamine administration, suggesting that basophils are the source of histamine. 41% of patients had arrhythmias in the post bypass period. The rise in histamine levels was not related to the incidence of cardiac arrhythmias.

Adult↗
PubMed2005

Sevoflurane (12% and 8%) inhalational induction in children.

BACKGROUND: Sevoflurane induction of anesthesia is frequently used in children. Rapidly performed inhalational induction may reduce excitation during early anesthesia. Increasing the total anesthetic MAC delivered to patients can be achieved by increasing volatile concentration or adding nitrous oxide. The latter reduces inspired oxygen concentration delivered, which may not be desirable. Even 8% sevoflurane induction is associated with excitation. A system capable of delivering 12% sevoflurane using two tandem vaporizers has been developed. METHODS: A randomized double blind study was undertaken to assess whether 12% sevoflurane offered any advantage over 8% in time and quality of induction. Sixty children aged 5-10 years were recruited and received either 12 or 8% sevoflurane. Time to loss of eyelash reflex, central pupils, incidence of adverse events, induction quality, systolic blood pressure and heart rate were recorded. RESULTS: Twelve percent sevoflurane reduced time to loss of eyelash reflex compared with 8% [mean (sd): 35 (12) and 46 (14) P<0.05], but the reduction was only 10% higher than the error in the measurement (assessment every 10 s). Twelve percent sevoflurane offered significantly better quality of induction (P<0.05). There was no difference in cardiovascular stability between groups, although heart rate rose significantly in both groups. Maintaining sevoflurane at 12% for 4 min caused significant amounts of apnea (69% with 12% and 38% with 8%, P<0.05). CONCLUSION: Twelve percent sevoflurane offers a smoother anesthesia induction than 8% in children of this age with no additional consequences for the cardiovascular system.

Anesthesia, Inhalation↗
PubMed2004

Diffusion of single cardiac ryanodine receptors in lipid bilayers is decreased by annexin 12.

Diffusion of cardiac ryanodine receptors (RyR2) in lipid bilayers was characterized. RyR2 location was monitored by imaging fluo-3 fluorescence due to Ca2+ flux through RyR2 channels or fluorescence from RyR2 conjugated with Alexa 488 or containing green fluorescent protein. Single channel currents were recorded to ensure that functional channels were studied. RyR2 exhibited an apparent diffusion coefficient (DRyR) of 1.2 x 10(-8) cm2 s(-1) and a mean path length of 5.0 microm. Optimal use of optical methods for analysis of RyR2 channel function requires that RyR2 diffusion be limited. Therefore, we tested the effect of annexin 12, which interacts with anionic phospholipids in a Ca2+-dependent manner. Addition of annexin 12 (0.25-4.0 microM) to the trans side of bilayers containing an 80:20 ratio of phosphatidylethanolamine/phosphatidylserine decreased RyR2 diffusion in a concentration-dependent manner. Annexin 12 (2 microM) decreased the apparent DRyR 683-fold from 1.2-10(-8) to 1.8 x 10(-11) cm2 s(-1) and the mean path length 10-fold from 5.0 to 0.5 micro m without obvious changes in the conductance of the native bilayer or in activation of RyR2 channels by Ca2+ or suramin. Thus, annexin 12 may provide a useful tool for optimizing optical analysis of RyR2 channels in lipid bilayers.

Animals↗
PubMed2004

Comparison of the analgesic efficacy and plasma concentrations of high-dose intra-articular and intramuscular morphine for knee arthroscopy.

BACKGROUND AND OBJECTIVE: It is important to provide good postoperative analgesia after discharge from day case surgery. The usefulness of intra-articular morphine for analgesia after day case knee arthroscopy remains controversial. A large dose of morphine intra-articularly may provide a good long-lasting analgesia, but its efficacy and pharmacokinetics are not known and may be no better than intramuscular morphine. We compared the effect of 10 mg intra-articular and intramuscular morphine for 24 h post-injection in a randomized double-blind study. METHODS: Forty adults undergoing knee arthroscopy were recruited and received either 10mg morphine intra-articularly or intramuscularly. Our primary outcome was overall visual analogue assessment of pain (0-100 mm scale where 0 is no pain and 100 is worst possible pain) between 4 h (on discharge) and 24 h (post-operatively). Plasma morphine concentrations were measured at 15 min, and 1, 2, 4 and 24 h. The use of additional analgesia was noted. RESULTS: The assessment of pain experienced between discharge (4 h) and 24 h was significantly better in the intra-articular (n = 20; mean+/-SD: 18+/-19) than the intramuscular (n = 19; mean+/-SD: 34+/-20) group (P = 0.027). The number of patients consuming any additional analgesia between discharge and 24 h was significantly lower in the intra-articular morphine group (P = 0.038), with 4 (20%) patients in the intra-articular group and 11 (60%) patients in the intramuscular group consuming supplementary analgesia. There were no differences in plasma morphine concentrations between the groups. CONCLUSIONS: A large dose of intra-articular morphine provided better analgesia than the same dose of intramuscular morphine, low plasma morphine levels suggesting a peripheral mechanism.

Adult↗
PubMed2004

A comparison of 8% and 12% sevoflurane for inhalation induction in adults.

Sevoflurane is a non-pungent volatile anaesthetic agent with a low blood-gas solubility coefficient. It has been studied in concentrations of up to 8% for induction of anaesthesia. Previous work has suggested that there may be a ceiling effect with increasing concentration of sevoflurane above 6%, but there are no published studies using 12% sevoflurane. This study compared 8 and 12% sevoflurane to induce anaesthesia in adults. Sevoflurane was administered using two adapted datum vaporisers with the interlock removed. Induction with 12% sevoflurane compared to 8% sevoflurane produced a significant decrease in the time to achieve central pupils, corresponding to surgical anaesthesia and the third part of Guedel's stage 3 of anaesthesia (mean time (SD) 201 s (81) and 247 s (39), respectively, p < 0.05). Twelve-percent sevoflurane produced a similar stable cardiovascular profile to 8% sevoflurane, and there was no increase in respiratory complications.

Adult↗
PubMed2004

The effect of mechanically-induced cricoid force on lower oesophageal sphincter pressure in anaesthetised patients.

In the United Kingdom, cricoid force is central to upper airway management in obstetric and emergency anaesthesia. A reduction in oesophageal barrier pressure (OBP) in these patients may increase regurgitation risk. This study investigated whether the application of cricoid force to anaesthetised patients reduced lower oesophageal sphincter pressure (LOSP) and consequently OBP. Anaesthesia was induced in 29 patients using a standard protocol. An oesophageal balloon catheter was inserted and gastric trace identified. The catheter was withdrawn incrementally and pressure readings recorded at each position before and during the application of 30 N cricoid force, with a sudden rise in pressure indicating lower oesophageal sphincter position. Oesophageal barrier pressure was calculated as the difference between LOSP and gastric pressure. Application of cricoid force significantly reduced OBP without influencing gastric pressure (p < 0.001). The use of cricoid force may increase the risk of gastroesophageal reflux in anaesthetised patients.

Adult↗
PubMed2004

Evaluation of Frova, single-use intubation introducer, in a manikin. Comparison with Eschmann multiple-use introducer and Portex single-use introducer.

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.

Analysis of Variance↗
PubMed2004

The Cardiff paediatric laryngoscope blade: a comparison with the Miller size 1 and Macintosh size 2 laryngoscope blades.

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.

Adolescent↗