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Wiley Online Library : Anaesthesia
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A systematic review of information format and timing before scheduled adult surgery for peri-operative anxiety

11. September 2017 - 6:42
Summary

We included 34 trials with 3742 participants, identified through 6 database and supplementary searches (to May 2017): 29 were randomised; 4 were quasi-randomised and 1 was cluster-randomised. Disparate measurements and outcomes precluded meta-analyses. Blinding was attempted in only 6 out of 34 (18%) trials. A multimedia format, alone or in combination with text or verbal formats, was studied in 20/34 (59%) trials: pre-operative anxiety was unaffected in 10 out of 14 trials and reduced by the multimedia format in three; postoperative anxiety was unaffected in four out of five trials in which formats were compared. Multimedia formats increased knowledge more than text, which in turn increased knowledge more than verbal formats. Other outcomes were unaffected by information format. The timing of information did not affect pre-operative anxiety, postoperative pain or length of stay. In conclusion, the effects of pre-operative information on peri-operative anxiety and other outcomes were affected little by format or timing.

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Epidural pressure waveforms

11. September 2017 - 6:42
Categories: From Anaesthesia

Current options in aerosolised drug therapy for children receiving respiratory support

5. September 2017 - 11:21
Summary

Inhalation of aerosolised medications are the mainstay of treatment for a number of chronic lung diseases and have several advantages over systemically-administered medications. These include more rapid onset of action for drugs such as β-adrenergic agonists when compared with oral medication, high luminal doses for inhaled antibiotics when used to treat endobronchial infection, and an improved therapeutic index compared with systemic delivery for these and other classes of drugs such as corticosteroids. The use of aerosolised drugs to treat patients whose tracheas are intubated is less well established, in part because systemic delivery via the intravenous route can be a simpler alternative for many drugs. Consequently, research in this area is largely limited to a number of in vitro studies and very few clinical trials. Unfortunately, a lack of focus in this area has resulted in a number of practices which at best are ineffective, and at worst dangerous for the patient. Although there have been some attempts to re-invigorate research in order to improve delivery systems, current devices are, to a great extent, based on long-standing technology developed more than 50 years ago. In this review, we explore current knowledge and provide guidance as to when and how the inhaled route may be of value when treating patients whose tracheas are intubated, and we set out the challenges facing those attempting to advance the topic. We conclude by reviewing current areas of interest that may lead to more effective and widespread use of aerosols in the treatment of intubated patients.

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Evidence of hysteresis in propofol pharmacodynamics

5. September 2017 - 10:55
Summary

It is commonly assumed that loss of responsiveness and recovery of responsiveness occur at similar concentrations of propofol. However, the ‘conscious’ and ‘anaesthetised’ conditions produced by general anaesthetics may behave as two bistable states. We hypothesised that loss of responsiveness and recovery of responsiveness occur at different propofol concentrations. Propofol was administered to 19 healthy volunteers by effect-site target-controlled infusion using increasing and decreasing stable concentration steps of 7 min. Propofol serum concentrations were measured from venous blood samples at the end of each 7-min step. A long step of 14 min was performed at loss of responsiveness. At this step, propofol concentrations were measured at 7 and 14 min. Propofol concentrations measured at loss of responsiveness and recovery of responsiveness were 2.6 (1.2–4.7) μg.ml−1 and 1.6 (0.6–3.3) μg.ml−1, respectively (p < 0.001). Propofol plasma concentration and the corresponding bispectral index values measured at minute 7 and minute 14 of the long step performed at loss of responsiveness were 2.6 (1.2–4.7) vs. 2.6 (1.3–4.3) at recovery of responsiveness, (p = 0.96) and 61.2 (49.0–77.0) vs. 58.4 (45.0–74.0), (p = 0.058), respectively. Loss of responsiveness and recovery of responsiveness appear to occur at different propofol concentrations. However, it is possible that, if equilibration was not achieved between plasma and effect-sites at the end of each 7-min step, the higher concentrations found at loss of responsiveness compared with those observed during recovery of responsiveness could be explained by a possible bias in estimations of the effect-site concentrations of propofol by the Schnider model, rather than neural inertia.

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The effect of acetazolamide on intra-ocular pressure after Trendelenburg positioning – a randomised double-blind crossover trial in volunteers

22. August 2017 - 7:12
Summary

Recent evidence suggests Trendelenburg positioning can produce a significant rise in intra-ocular pressure. Peri-operative vision loss in patients undergoing laparoscopic colorectal surgery has been reported with the rise in intra-ocular pressure suggested as a possible factor. Acetazolamide decreases intra-ocular pressure by reducing the formation of aqueous humour, so we aimed to investigate if it could attenuate the intra-ocular pressure rise that can occur in the Trendelenburg position. Nine healthy volunteers were recruited and randomly assigned to a double-blind crossover comparison of placebo or acetazolamide with a minimal 4 days’ washout period before the second study day. One and a half hours after taking the medication, volunteers lay head-down at 17° for 4 h. Intraocular pressure measurements were repeated in both eyes every 30 min over a 4-h period. There were two males and seven female volunteers, with a mean (SD) age of 54.3 (18.5) years. The mean (SD) increase in intra-ocular pressure following 4 h in the Trendelenburg position was 3.17 (4.63) mmHg after the placebo, and 0.02 (4.01) mmHg (p = 0.02) after acetazolamide. We have shown than acetazolamide can attenuate the rise that occurs in intra-ocular pressure when in the Trendelenburg position.

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Size matters

14. August 2017 - 12:08
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Ultrasound assessment of gastric contents in children undergoing elective ear, nose and throat surgery: a prospective cohort study

14. August 2017 - 10:45
Summary

Ultrasound examination of the gastric antrum allows reliable assessment of gastric contents and volume. Postoperative assessment of gastric contents before recovery from anaesthesia could help the physician to choose the most appropriate extubation technique after surgery in children. In this prospective observational study, we assessed whether significant changes occurred in gastric contents during the intra-operative period in children undergoing elective ear, nose and throat (ENT) surgery. Children aged between six months and 16 years were recruited consecutively. Ultrasound examination of the antrum was performed before induction of anaesthesia and at the end of surgery before tracheal extubation, and included quantitative and qualitative assessment of gastric contents. The mean (SD) gastric volume was 0.28 (0.30) ml.kg−1 before surgery and 0.27 (0.30) ml.kg−1 after surgery, p = 0.82. No solid contents were identified in the antrum, and the gastric volume was < 1.5 ml.kg−1 in all patients during both ultrasound examinations. Our results suggest that, after elective ENT surgery, children are not at risk of a full stomach before tracheal extubation, and that pulmonary aspiration of blood that may occur after elective ENT surgery is probably not related to regurgitation of ingested blood from the stomach.

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A comparison of gastric emptying of soluble solid meals and clear fluids matched for volume and energy content: a pilot crossover study

14. August 2017 - 10:40
Summary

We previously demonstrated that the gastric emptying time of different liquids with the same volume mainly depended on their energy content, regardless of differences in composition. In this crossover study, we investigated whether the same applies when soluble solid foods are ingested with water. Ten healthy volunteers ingested one of five test diets consisting of two test meals (Calorie Mate® 100 and 200 kcal) and three test solutions (water and glucose solutions of 100 and 200 kcal), each given in a volume of 400 ml, and then underwent ultrasonography to measure the gastric antral cross-sectional area every 10 min for 120 min. The gastric emptying time was defined as the time for the antral cross-sectional area to revert to its initial value. When test diets with the same energy content were ingested, the gastric emptying curves were nearly identical, regardless of whether the original form was solid or liquid. The median (IQR[range]) gastric emptying times of Calorie Mate® of 100 kcal with water vs. isocaloric glucose solution were 65 (60–78 [50–80]) vs. 65 (60–70 [50–80]) min (p = 0.58), and for Calorie Mate® of 200 kcal with water vs. isocaloric glucose solution they were 100 (93–108 [90–120]) vs. 105 (90–110 [90–120]) min (p = 0.54). The median (IQR [range]) for water was 40 (30–40 [30–50]) min. Energy content may be a critical determinant of the gastric emptying time when ingesting soluble solid diets with water.

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Issue Information – Editorial Board

14. August 2017 - 8:01
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A randomised trial comparing real-time double-lumen endobronchial tube placement with the Disposcope® with conventional blind placement

14. August 2017 - 8:01
Summary

Double-lumen endobronchial tube placement is challenging. This study compared double-lumen tube placement with the Disposcope®, a wireless videostylet allowing real-time visualisation, with conventional blind placement. Patients undergoing elective thoracic surgery with normal airways requiring one-lung ventilation were randomly allocated into two groups (27 patients in each group). The Disposcope was used to assist left-sided double-lumen tube placement in one group, and conventional blind placement was performed in the control group. Placement in both groups was checked with fibreoptic bronchoscopy. The Disposcope-assisted group had a shorter total mean (SD) placement time (18.6 (2.5) s vs. 21.4 (2.9) s, p < 0.001), laryngoscopy to end of auscultation time (83.4 (3.0) s vs. 93.9 (5.7) s, p < 0.001) and total operation time (130.7 (6.1) s vs. 154.5 (6.3) s, p < 0.001). In the Disposcope-assisted group, the double-lumen tube was inserted in the correct side in all patients (100.0%), whereas in the conventional group, the double-lumen tube was placed in the correct side in 25 (92.6%) patients and in the wrong side in 2 (7.4%) patients; the difference was not significant (p = 0.150). In the Disposcope-assisted group, the double-lumen tube was inserted to the optimal depth in 24 (88.9%) patients, whereas in the conventional group it was inserted to the optimal depth in one (4.0%) patient. The Disposcope increased the success rate of double-lumen tube placement, and shortened the total operation time when compared with standard placement with confirmation using fibreoptic bronchoscopy, and may replace the conventional method.

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