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Wiley Online Library : Anaesthesia
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Evaluation of a novel waste anaesthetic gas scavenger device for use during recovery from anaesthesia

2. November 2017 - 10:52
Summary

Volatile anaesthetic agents are a potential occupational health hazard to theatre and recovery staff. Operating theatres and anaesthetic rooms are required to be equipped with scavenging systems, but recovery units often are not. We compared exhaled, spectrophotometric sevoflurane and desflurane concentrations 15 cm from the mouth (‘patient breathing zone’) and 91 cm laterally to the patient (‘nurse work zone’) in 120 patients after tracheal extubation who were consecutively allocated to either ISO-Gard mask oxygen/scavenging or standard oxygen mask, 0 min, 10 min and 20 min after arrival in the theatre recovery unit. Median (IQR [range]) duration of anaesthesia was similar between groups (control 76 (44–119 [15–484]) min vs. study group 90 (64–130 [15–390]) min, p = 0.136). Using the ISO-Gard mask, the 20-min mean patient breathing zone and nurse work zone exhaled anaesthetic levels were ~ 90% and 78% lower than those recorded in the control group, respectively, and were within the recommended 2 ppm maximum environmental exposure limit in the patient breathing zone of 53 out of 60 (88%) and the nurse work zone of all 60 (100%) patients on first measurement in the recovery room (vs. 10 out of 60 (17%) and 40 out of 60 (67%) in the control group). Our study indicates that the ISO-Gard oxygen/scavenging mask reduces the level of exhaled sevoflurane and desflurane below recommended maximum exposure limits near > 85% of extubated patients within ~ 20 s of application in the recovery unit after surgery. We encourage the use of this mask to minimise the occupational exposure of recovery staff to exhaled volatile agents.

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Human cadavers preserved using Thiel's method for the teaching of fibreoptically-guided intubation of the trachea: a laboratory investigation

1. November 2017 - 12:00
Summary

We assessed the suitability of human cadavers preserved using Thiel's method for teaching flexible fibreoptic tracheal intubation. Thirty-one anaesthetists unacquainted with this technique received didactic teaching followed by handling of the fibrescope on the Oxford teaching box. They then carried out fibreoptic intubations in two cadavers to establish a baseline sample of their intubation skills. Thereafter, we randomly assigned the trainees to two groups to practice fibreoptic intubation either on two distinct cadavers or on two airway manikins. After 7 days we re-assessed procedural skills using the same cadavers as at baseline. Intubation time was the primary outcome and secondary outcomes included the incidence of failed intubations. We also evaluated trainee satisfaction. The mean (SD) intubation time decreased from a baseline value of 74 (20) s to 35 (6) s in the cadaver group and to 56 (16) s in the manikin group. The effect of ‘time’ was significant (p = 0.002), indicating that both methods of training led to improvements. The training effect of the cadaveric method was greater than with the manikin method (p = 0.0016). Thirty-four failed intubations occurred at baseline vs. eight at the end of study (RR 0.24, 95%CI 0.11–0.51, p = 0.0002, NNT 9.6); six in the cadaver group and two in the manikin group (p = 0.22). We conclude that human cadavers preserved using Thiel's method are potentially better for teaching flexible fibreoptic tracheal intubation compared with manikins.

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Learning from the Law. A review of 21 years of litigation for pain during caesarean section

1. November 2017 - 12:00
Summary

The large majority of caesarean sections in the UK are now carried out under neuraxial anaesthesia. Although this technique is widely accepted as being the safest option in most circumstances, the use of regional anaesthesia increases the risk of patients experiencing intra-operative discomfort or pain. Pain during operative obstetric delivery is the commonest successful negligence claim relating to regional anaesthesia against obstetric anaesthetists in the UK. In the following article, using a database of over 360 cases spanning 21 years, we break down and examine the recurrent components of medicolegal claims concerning pain during caesarean section and consider how anaesthetists might avoid litigation.

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Maternal cardiac output response to colloid preload and vasopressor therapy during spinal anaesthesia for caesarean section in patients with severe pre-eclampsia: a randomised, controlled trial

31. October 2017 - 11:05
Summary

We examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre-eclampsia. Twenty patients with pre-delivery spinal hypotension were randomly allocated to receive an initial dose of either 50 μg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300-ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min−1.m−2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min−1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049). Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min−1.m−2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 [50–150] μg phenylephrine or 15 [7.5–37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at −12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at −9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. −1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesia-induced haemodynamic changes in severe pre-eclampsia, if left ventricular systolic function is preserved.

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Peripheral nerve block in ankle fracture surgery: a qualitative study of patients’ experiences

20. October 2017 - 4:20
Summary

Peripheral nerve blocks are popular as a mode of anaesthesia for limb surgery and their beneficial effects are well documented in elective surgery. However, concerns have been raised about potential rebound pain outweighing the benefits in acute ankle fracture surgery. Furthermore, pain scores and morphine consumption do not provide a full picture, as pain is subjective. To evaluate the clinical usefulness of peripheral nerve blocks, we explored patients’ expectations and experiences by means of semi-structured interviews analysed with systematic text condensation. We obtained ethical approval and informed consent and sampled purposively among adult patients scheduled for ankle surgery with nerve blocks as the primary mode of anaesthesia. Patients were interviewed within 48 h postoperatively. Data saturation was reached after 13 interviews. We found that, despite pre-emptive ibuprofen and paracetamol, some patients did experience excruciating rebound pain for up to 2 h, although most had little or no pain. The patients had doubts about what to do when the block wore off, which led to a risk of unnecessary pain levels or morphine overuse. Patients had difficulty understanding the effect and course of the nerve blocks. They had misunderstandings regarding the blocks’ effect on sensation, resulting in fear of feeling pain during surgery and of permanent nerve damage after surgery. However, patients valued the mental alertness, ability to ambulate and efficient pain relief provided by the blocks. We recommend that patients be given thorough and repeated information as we feel this is crucial in preventing undesirable responses from patients, and is likely to increase the overall clinical usefulness of nerve blocks in acute limb surgery.

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Correction

19. October 2017 - 5:27
Categories: From Anaesthesia

Correction

19. October 2017 - 5:27
Categories: From Anaesthesia

Apnoeic oxygenation with high-flow nasal oxygen for laryngeal surgery: a case series

19. October 2017 - 5:27
Summary

Surgery under apnoeic conditions with the use of high-flow nasal oxygen is novel. Between November 2016 and May 2017, 28 patients underwent tubeless laryngeal or tracheal surgery under apnoeic conditions with high-flow nasal oxygen as the sole method of gas exchange. Patients received total intravenous anaesthesia and neuromuscular blocking agents for the duration of their surgery. The median (IQR [range]) apnoea time was 19 (15–24 [9–37]) min. Four patients experienced an episode of oxygen desaturation to a value between 85% and 90%, lasting less than 2 min in each case. Median (IQR [range]) end-tidal carbon dioxide (ETCO2) level following apnoea was 8.2 (7.2–9.4 [5.8–11.8]) kPa. The mean (SD) rate of ETCO2 increase was 0.17 (0.07) kPa.min−1 from an approximated baseline value of 5.00 kPa. Venous blood sampling from 19 patients demonstrated a mean (SD) partial pressure of carbon dioxide (PVCO2) of 6.29 (0.71) kPa at baseline and 9.44 (1.12) kPa after 15 min of apnoea. This equates to a mean (SD) PVCO2 rise of 0.21 (0.08) kPa.min−1 during this period. Mean (SD) pH was 7.40 (0.03) at baseline and 7.23 (0.04) after 15 min of apnoea. Mean (SD) standard bicarbonate was 26.7 (1.8) mmol.l−1 at baseline and 25.4 (1.8) mmol.l−1 at 15 min. We conclude that high-flow nasal oxygen under apnoeic conditions can provide satisfactory gas exchange in order to allow tubeless anaesthesia for laryngeal surgery.

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