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British Journal of Anaesthesia - current issue

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  1. Optimal volume of local anaesthetic for adductor canal block: using the continual reassessment method to estimate ED95

    Theoretically, the ideal volume of local anaesthetic for adductor canal block (ACB) would ensure sufficient filling of the canal and avoid proximal spread to the femoral triangle. In this dose-finding study, we aimed to investigate the minimal effective volume for an ACB needed to fill the adductor canal distally in at least 95% of patients (ED95).


    We performed a blinded trial, enrolling 40 healthy men. All subjects received an ACB with lidocaine 1%. Volumes were assigned sequentially to the subjects using the continual reassessment method followed by Bayesian analysis to determine the ED95. Distal filling of the adductor canal was assessed by magnetic resonance imaging (primary outcome). Secondary outcomes were the effect of volume on proximal spread to the femoral triangle (also assessed by magnetic resonance imaging), quadriceps muscle weakness (decrease by ≥25% from baseline) and sensory block.


    The ED95 was 20 ml, with an estimated probability of sufficiently filling the canal of 95.1% (95% credibility interval: 0.91–0.98). Proximal spread to the femoral triangle was seen in 0/4 (0%), 7/12 (58%), 4/8 (50%), and 8/16 (50%) subjects with the 5, 10, 15, and 20 ml doses, respectively (P=0.25). Seven subjects had a reduction in muscle strength, but there was no difference between groups (P=0.85).


    For an ACB, the dose closest to the ED95 needed to fill the adductor canal distally was 20 ml. There was no significant correlation between volume and proximal spread or muscle strength.

    Clinical trial registration


  2. Comparative evaluation of the visibility and block characteristics of a stimulating needle and catheter vs an echogenic needle and catheter for sciatic nerve block with a low-frequency ultrasound probe

    Background. Clear visibility of the needle and catheter tip is desirable to perform safe and successful ultrasound-guided peripheral nerve blocks. This can be challenging with deeper blocks in obese patients. This study compared the visibility of echogenic and non-echogenic block needles and catheters in proximal sciatic blocks when performed with a low-frequency curved probe.

    Methods. Seventy-eight patients undergoing total knee joint arthroplasty were randomized to receive an ultrasound-guided continuous sciatic nerve block using either a non-echogenic needle and stimulating catheter or an echogenic needle and echogenic non-stimulating catheter. Block needles in both groups were placed using both neurostimulation and ultrasound guidance, after which the catheter was positioned using either neurostimulation alone (Stimulating group) or imaging alone (Echogenic group). Three anaesthetists blinded to group allocation graded video clips recorded during the blocks for nerve, needle and catheter visibility. Performance characteristics and block parameters were also compared.

    Results. No significant differences between the two groups were observed with regard to needle or catheter visibility (P=0.516). The Stimulating group required more needle redirections (P=0.009), had a longer procedure time [Echogenic median 274 s vs Stimulating 344 s (P=0.016)], and resulted in greater patient discomfort (P=0.012). There were no significant differences between the two groups in terms of block onset or completion time.

    Conclusions. Use of echogenic needles and catheters reduced procedure time and patient discomfort compared with a stimulating catheter system. There were no differences in the visibility scores of the two systems.

    Clinical trial registristration. CTR Protocol ID: R-11-495, Clinical Trials.Gov ID: NCT 01492660.

  3. RCoA spring symposium: perioperative medicine: RCPE, Edinburgh, UK, May 14-15, 2015
  4. Abstracts of the Spring Anaesthetic Research Society Meeting (ARS): The Royal College of Anaesthetists, London, UK, April 21-22, 2015
  5. Delirium in Critical Care
  6. Handbook of ICU Therapy
  7. Perioperative Transoesophageal Echocardiography: a Companion to Kaplan's Cardiac Anesthesia
  8. Clinical Anesthesia Fundamentals
  9. Predictors of early postoperative troponin increase after noncardiac surgery: a pilot study in a real-world population admitted to the recovery room
  10. Hazards of perioperative {beta}-blockers are likely to be dose related
  11. Haemodynamic monitoring: the inseparable relation of accuracy and trending
  12. Transitioning from routine to on-demand test ordering in intensive care units: a prospective, multicentre, interventional study
  13. Early thromboelastometry variables predict maximum clot firmness in children undergoing cardiac and non-cardiac surgery

    Early clot amplitudes measured on thromboelastometry (ROTEM®) predict maximum clot firmness (MCF) in adults. In this multicentre, retrospective study, we aimed to confirm the suspected relationship between early ROTEM® variables and MCF, in children undergoing cardiac or non-cardiac surgery.


    4762 ROTEM® tests (e.g. EXTEM, INTEM, FIBTEM, APTEM, and HEPTEM) performed in children undergoing cardiac or non-cardiac surgery at three University hospitals between January 2011 and June 2014 were reviewed. To assess the correlation between clot amplitudes measured after 5, 10 and 15 min and MCF, each variable was compared with the corresponding MCF by calculating Spearman's correlation coefficient.


    For the EXTEM® test, we observed that amplitude measured after 5 min (A5: r=0.91, P<0.001), 10 min (A10: r=0.95, P<0.001) and 15 min (A15: r=0.96, P<0.001) were strongly correlated to MCF. The same correlations were observed for INTEM® test (A5: r=0.93, P<0.001; A10: r=0.97, P<0.001; A15: r=0.97, P<0.001), and FIBTEM® test (A5: r=0.93, P<0.001; A10: r=0.94, P<0.001; A15: r=0.96, P<0.001). In addition, the amplitudes measured after five, 10 and 15 min were also strongly correlated with MCF in the APTEM® and the HEPTEM® tests. Receiver operating characteristics (ROC) analysis confirmed that A5, A10, A15 strongly predicted decreased MCF on all ROTEM® tests.


    This study confirmed that early values of clot amplitudes measured as soon as five, 10 or 15 min after clotting time could be used to predict maximum clot firmness in all ROTEM® tests.

  14. Ultrasound standard for popliteal sciatic block: circular expansion of the paraneural sheath with the needle in-plane from lateral-to-medial in the 'reverse Sim's position'
  15. Postoperative pain assessment in children: a pilot study of the usefulness of the analgesia nociception index

    The ability to perform objective pain assessment is very important in paediatric patients. The goal of this study was to investigate the relationship between the analgesia nociception index (ANI), which is based on the heart rate variability, and objective measurements of pain intensity in young or cognitively impaired children, after surgical or imaging procedures (control group) under general anaesthesia.


    On arrival in the recovery room and subsequently at 5–10 min intervals, the level of pain was rated using the FLACC pain scale (0–10). The ANI values (0–100; 0 indicating the worst pain) were recorded simultaneously. The area under the receiver operating characteristic curve (AUC) and grey zone approach were used to evaluate the performance of the ANI to detect patients with FLACC >4. Instantaneous ANI values were compared with ANI values averaged over 256 s periods of time.


    All children in the surgical group (n=32) developed moderate-to-severe pain (FLACC >4). Children in the control group (n=30) exhibited minimal pain. Instantaneous ANI values were lower in children of the surgical group than in the control group [52 (sd16) vs 69 (16), P<0.001]. The AUC for the 256 s ANI recording period [0.94 (95% confidence interval 0.85–0.99)] was significantly higher than for instantaneous ANI (P<0.05). When measured for a period of 256 s, an ANI cut-off value of 56 (grey zone [58–60]) was most predictive of a FLACC ≥4.


    The ANI may provide an objective measurement of acute postoperative pain, which is correlated with that measured on a FLACC scale in young or cognitively impaired children.