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British Journal of Anaesthesia - current issue

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  1. Oh's Intensive Care Manual
  2. Advanced Training in Anaesthesia--the Essential Curriculum
  3. Effects of early and late diabetic neuropathy on sciatic nerve block duration and neurotoxicity in Zucker diabetic fatty rats
    Background

    The neuropathy of type II diabetes mellitus (DM) is increasing in prevalence worldwide. We aimed to test the hypothesis that in a rodent model of type II DM, neuropathy would lead to increased neurotoxicity and block duration after lidocaine-induced sciatic nerve block when compared with control animals.

    Methods

    Experiments were carried out in Zucker diabetic fatty rats aged 10 weeks (early diabetic) or 18 weeks (late diabetic, with or without insulin 3 units per day), and age-matched healthy controls. Left sciatic nerve block was performed using 0.2 ml lidocaine 2%. Nerve conduction velocity (NCV) and F-wave latency were used to quantify nerve function before, and 1 week after nerve block, after which sciatic nerves were used for neurohistopathology.

    Results

    Early diabetic animals did not show increased signs of nerve dysfunction after nerve block. In late diabetic animals without insulin vs control animals, NCV was 34.8 (5.0) vs 41.1 (4.1) ms s–1 (P<0.01), and F-wave latency was 7.7 (0.5) vs 7.0 (0.2) ms (P<0.01), respectively. Motor nerve block duration was prolonged in late diabetic animals, but neurotoxicity was not. Late diabetic animals receiving insulin showed intermediate results.

    Conclusions

    In a rodent type II DM model, nerves have increased sensitivity for short-acting local anaesthetics without adjuvants in vivo, as evidenced by prolonged block duration. This sensitivity appears to increase with the progression of neuropathy. Our results do not support the hypothesis that neuropathy due to type II DM increases the risk of nerve injury after nerve block.

  4. Sevoflurane preconditioning-induced neuroprotection is associated with Akt activation via carboxy-terminal modulator protein inhibition
    Background

    Sevoflurane preconditioning has a neuroprotective effect, but the underlying mechanism is not fully understood. The aim of the present investigation was to evaluate whether sevoflurane-induced cerebral preconditioning involves inhibition of carboxy-terminal modulator protein (CTMP), an endogenous inhibitor of Akt, in a rat model of focal cerebral ischaemia.

    Methods

    Male Sprague–Dawley rats were exposed to 2.7% sevoflurane for 45 min. One hour later, rats were subjected to 60 min of focal cerebral ischaemia. The phosphoinositide 3-kinase inhibitors wortmannin and LY294002 were administered 10 min before preconditioning. Rats in the lentiviral transduction group received an intracerebroventricular injection of lentiviral vector Ubi-MCS-CTMP 3 days before ischaemia. Neurological deficits and infarct volumes were evaluated 24 h and 7 days after reperfusion. Phosphorylation of Akt, glycogen synthase kinase-3β (GSK3β), and expression of CTMP were determined at 1, 3, 12, and 24 h after reperfusion. Akt activity was measured at 3 h after reperfusion.

    Results

    Sevoflurane preconditioning improved neurological score and reduced infarct size at 24 h of reperfusion. Pretreatment with wortmannin or LY294002 attenuated these neuroprotective effects. Expression of CTMP correlated with reduced Akt activity after ischaemia, while sevoflurane preconditioning preserved Akt activity and increased phosphorylation of GSK3β. CTMP over-expression diminished the beneficial effects of sevoflurane preconditioning.

    Conclusions

    Activation of Akt signalling via inhibition of CTMP is involved in the mechanism of neuroprotection provided by sevoflurane preconditioning.

  5. Ultrasound-guided popliteal sciatic nerve block using a pocket-sized ultrasound machine: preliminary evidence
  6. Practical Management of Pain
  7. Bone cement embolism attached to central venous catheter
  8. Randomized comparison of experts and trainees with nasal and oral fibreoptic intubation in children less than 2 yr of age
    Background

    We hypothesized that the time to successful fibreoptic tracheal intubation through the nasal route would be faster than the oral route for both experts and trainees in children <2 yr of age.

    Methods

    One hundred children, 24 months and under in age, were randomized to an operator (expert or trainee), and route (nasal or oral) for fibreoptic tracheal intubation. Three separate times were then measured: (i) time to first glottic view, (ii) time to carinal view, and (iii) total time to successful tracheal intubation. The number of attempts made, manoeuvres needed to obtain an adequate laryngeal view, and manoeuvres for tracheal tube passage were also recorded.

    Results

    Time to successful tracheal intubation was significantly faster for experts than trainees. There was no difference in the time to tracheal intubation between the nasal and oral routes for experts. In trainees, intubation times were shorter for the nasal route—median (inter-quartile range) time (s) to carinal view was 35 (27–63) for the nasal route vs 59 (38–94) for the oral route (P=0.03), and the median time to successful tracheal intubation were 62 (49–122) vs 117 (61–224), P=0.05, for the nasal and oral routes, respectively. For trainees, the oral route required a greater number of airway manoeuvres for adequate laryngeal views and passage of the tracheal tube compared with the nasal route.

    Conclusions

    For clinicians with less experience in using paediatric bronchoscopes, fibreoptic tracheal intubation through the nasal route may be a more straightforward process than the oral route in children <2 yr of age.

    Clinical trial registration

    NCT02029300 (www.clinicaltrials.gov).

  9. Metabolic monitoring in the intensive care unit: a comparison of the Medgraphics Ultima, Deltatrac II, and Douglas bag collection methods
    Background

    The accuracy of oxygen consumption measurement by indirect calorimeters is poorly validated in mechanically ventilated intensive care patients where multiple confounders exist. This study sought to compare the Medgraphics Ultima (MGU) and Deltatrac II (DTII) devices, and the Douglas bag (DB) technique in mechanically ventilated patients at rest.

    Methods

    Prospective comparison of oxygen consumption measurement using three indirect calorimetry techniques in stable, resting mechanically ventilated patients at rest. Oxygen consumption (VO2), carbon dioxide production (VCO2), resting energy expenditure (REE), and respiratory quotient (RQ) were recorded breath-by-breath by the MGU over a 30–75 min period. During this time, simultaneous measurements were taken using the DTII, the DB, or both.

    Results

    While there was no systematic error (bias) between measurements made by the three techniques (VO2: MGU vs DTII 3.6%, MGU vs DB 3.3%), the limits of agreement were wide (VO2: MGU vs DTII 33%, MGU vs DB 54%).

    Conclusions

    Resting oxygen consumption values in stable mechanically ventilated patients measured by the three techniques showed acceptable bias but poor precision. There is an important clinical and research need to develop new indirect calorimeters specifically tailored to measure oxygen consumption during mechanical ventilation.

  10. Exercise: the new premed
  11. Effect of prehabilitation on objectively measured physical fitness after neoadjuvant treatment in preoperative rectal cancer patients: a blinded interventional pilot study
    Background

    Patients requiring surgery for locally advanced rectal cancer often additionally undergo neoadjuvant chemoradiotherapy (NACRT), of which the effects on physical fitness are unknown. The aim of this feasibility and pilot study was to investigate the effects of NACRT and a 6 week structured responsive exercise training programme (SRETP) on oxygen uptake $$(\dot{\mathrm{V}}{\hbox{ O }}_{2})$$ at lactate threshold ($${\hat{\theta }}_{\mathrm{L}}$$) in such patients.

    Methods

    We prospectively studied 39 consecutive subjects (27 males) with T3–4/N+ resection margin threatened rectal cancer who completed standardized NACRT. Subjects underwent cardiopulmonary exercise testing at baseline (pre-NACRT), at week 0 (post-NACRT), and week 6 (post-SRETP). Twenty-two subjects undertook a 6 week SRETP on a training bike (three sessions per week) between week 0 and week 6 (exercise group). These were compared with 17 contemporaneous non-randomized subjects (control group). Changes in $$\dot{\mathrm{V}}{\hbox{ O }}_{2}$$ at $${\hat{\theta }}_{\mathrm{L}}$$ over time and between the groups were compared using a compound symmetry covariance linear mixed model.

    Results

    Of 39 recruited subjects, 22 out of 22 (exercise) and 13 out of 17 (control) completed the study. There were differences between the exercise and control groups at baseline [age, ASA score physical status, World Health Organisation performance status, and Colorectal Physiologic and Operative Severity Score for the Enumeration of Mortality and Morbidity (CR-POSSUM) predicted mortality]. In all subjects, $$\dot{\mathrm{V}}{\hbox{ O }}_{2}$$ at $${\hat{\theta }}_{\mathrm{L}}$$ significantly reduced between baseline and week 0 [–1.9 ml kg–1 min–1; 95% confidence interval (CI) –1.3, –2.6; P<0.0001]. In the exercise group, $$\dot{\mathrm{V}}{\hbox{ O }}_{2}$$ at $${\hat{\theta }}_{\mathrm{L}}$$ significantly improved between week 0 and week 6 (+2.1 ml kg–1 min–1; 95% CI +1.3, +2.9; P<0.0001), whereas the control group values were unchanged (–0.7 ml kg–1 min–1; 95% CI –1.66, +0.37; P=0.204).

    Conclusions

    NACRT before rectal cancer surgery reduces physical fitness. A structured exercise intervention is feasible post-NACRT and returns fitness to baseline levels within 6 weeks.

    Clinical trial registration

    NCT: 01325909.

  12. General multimodal or scheduled risk-adopted postoperative nausea and vomiting prevention: just splitting hairs?
  13. Skin pigmentation interferes with the clinical measurement of regional cerebral oxygen saturation
    Background

    Devices utilizing near-infrared (NIR) spectroscopy have been used to assess regional intracerebral oxygen saturation (rSO2) during anaesthesia for a decade. The presence of wide differences among individuals reduces their applicability to steady-state measurements. Current devices may not adequately account for variations in skin pigmentation.

    Methods

    From our ongoing departmental registry, 3282 consecutive patients underwent cardiac surgery between 2010 and 2012 and their pre-induction measurements of rSO2 were available. Of these, 2096 identified themselves as Caucasian (Cauc) and 1186 as African-American (AA). Pre-induction rSO2, clinical and operative features were compared.

    Results

    Clinical and operative details of these patients differed widely between the two populations. High-risk features were more common in AA patients, but no difference in mortality was observed (4.8% in AAs vs 4.7% in Caucs, P=0.87). Preprocedure rSO2 was systematically higher in Cauc (65.5% vs 53.3%, P<0.001). After multivariate linear regression adjustment, AA ethnicity proved to be associated independently with low rSO2 [odds ratio (OR) –8.28, 95% confidence interval (CI) –9.12 to –7.44, P<0.001]. Multivariate logistic regression analysis showed that preprocedural rSO2 was independently associated with operative mortality both in the Cauc group (OR 0.97, 95% CI 0.96–0.99, P=0.001) and in the AA group (OR 0.97, 95% CI 0.95–0.99, P=0.01).

    Conclusions

    AAs have a lower rSO2 than Caucs as measured by the INVOS 5100C cerebral oximeter. Reasonably, this could be attributed to attenuation of the NIR light by skin pigment. Despite this limitation, in both ethnic groups, lower preoperative rSO2 was predictive of greater operative mortality.

  14. Neurological complications of surgery and anaesthesia

    Injury to the central and peripheral nervous systems is often permanent. As such, adverse neurological outcomes of surgery and anaesthesia can be devastating for patients and their families. In this article, we review the incidence, risk factors, outcomes, prevention, and treatment of a number of important neurological complications in the perioperative period.

  15. Sevoflurane post-conditioning increases nuclear factor erythroid 2-related factor and haemoxygenase-1 expression via protein kinase C pathway in a rat model of transient global cerebral ischaemia
    Background

    The antioxidant mechanism of sevoflurane post-conditioning-induced neuroprotection remains unclear. We determined whether sevoflurane post-conditioning induces nuclear factor erythroid 2-related factor (Nrf2, a master transcription factor regulating antioxidant defence genes) and haemoxygenase-1 (HO-1, an antioxidant enzyme) expression, and whether protein kinase C (PKC) is involved in Nrf2 activation, in a rat model of transient global cerebral ischaemia/reperfusion (I/R) injury.

    Methods

    Eighty-six rats were assigned to five groups: sham (n=6), control (n=20), sevoflurane post-conditioning (two cycles with 2 vol% sevoflurane inhalation for 10 min, n=20), chelerythrine (a PKC inhibitor; 5 mg kg–1 i.v. administration, n=20), and sevoflurane post-conditioning plus chelerythrine (n=20). The levels of nuclear Nrf2 and cytoplasmic HO-1 were assessed 1 or 7 days after ischaemia (n=10 each, apart from the sham group, n=3).

    Results

    On day 1 but not day 7 post-ischaemia, Nrf2 and HO-1 expression were significantly higher in the sevoflurane post-conditioning group than in the control group. Chelerythrine administration reduced the elevated Nrf2 and HO-1 expression induced by sevoflurane post-conditioning.

    Conclusions

    Sevoflurane post-conditioning increased Nrf2/HO-1 expression via PKC signalling in the early phase after transient global cerebral I/R injury, suggesting that activation of antioxidant enzymes may be responsible for sevoflurane post-conditioning-induced neuroprotection in the early phase after cerebral I/R injury.