Anaesthesia, 2011, 66, pages 311–322 Correspondence . ....................................................................................................................................................................................................................
W. H. L. Teoh M. K. Shah A. T. H. Sia KK Women’s & Children’s Hospital, Singapore Email:
[email protected]
No external funding and no competing interests declared. Previously posted at the Anaesthesia Correspondence website: http://www.anaesthe siacorrespondence.com.
References 1 Teoh WHL, Saxena S, Shah MK, Sia ATH. Comparison of three videolaryngoscopes: Pentax Airway Scope, C-MAC, Glidescope vs the Macintosh laryngoscope for tracheal intubation. Anaesthesia 2010; 65: 1126–32. 2 Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 39: 1105–11. 3 Ochroch EA, Hollander JE, Kush S, Shofer FS, Levitan RM. Assessment of laryngeal view: percentage of glottic opening score vs Cormack and Lehane grading. Canadian Journal of Anesthesia 1999; 46: 987–90. 4 Adnet F, Borron SW, Racine SX, et al. The intubation difficulty scale (IDS): proposal and evaluation of a new score characterizing the complexity of endotracheal intubation. Anesthesiology 1997; 87: 1290–7. doi: 10.1111/j.1365-2044.2011.06686.x
Laparoscopic assisted transversus abdominis plane block: a novel insertion technique during laparoscopic nephrectomy
We read the recent review article on trunk blocks for abdominal surgery [1] with great interest. The article described the transversus abdominis plane (TAP) block as a technique utilised in abdominal and gynaecological surgery. Local anaesthetic solution is infiltrated into the neurovascular plane between the transversus abdominis muscle and internal oblique
muscle of the lateral abdominal wall. The aim is to block the lower thoracic and first lumbar nerves as they pass anteriorly [2]. Following skin penetration, a ‘double pop’ is felt when passing through the fascia of the external oblique and internal oblique muscles. We found seven published clinical trials comparing the efficacy of TAP blocks against standard techniques, and a recent review of these trials described improved pain scores and reduced opioid consumption after anterior abdominal wall surgery augmented by a TAP block [3]. Early methods used the lumbar triangle of Petit as an entry point for a blind ‘2-pop’ technique, although ultrasound guidance has become more frequently employed, identifying the neurovascular plane midway between the iliac crest and the subcostal margin [2, 3]. In our experience using ultrasound, the 2-pop technique can be unreliable as a final endpoint. We find that the local anaesthetic may be injected above, in or below the true TAP. The ultrasound anatomy also shows that the transversus abdominis muscle is a very thin muscle. Often, a second pop is not felt as the needle passes though the TAP, which risks penetration of the peritoneum. We have developed a novel ‘semiblind’ technique of administering the TAP block, utilising the presence of the laparoscopic camera. After creation of pneumoperitoneum under direct vision, the laparoscopic camera is positioned to view the region of the lateral abdominal wall where the TAP block will be infiltrated. The blunted needle is introduced externally through the skin as per a standard blind 2-pop technique. Where our technique is unique is that the block is performed under direct vision internally. This ensures that the second pop is not intra-peritoneal and there is no risk to intra-abdominal contents. On injection of local anaesthetic, ‘Doyle’s internal bulge sign’ can be seen as the transversus abdominis muscle with peritoneum is pushed
Anaesthesia 2011 The Association of Anaesthetists of Great Britain and Ireland
Figure 1 Pre-TAP block view from the
laparoscopic camera directed at the antero-lateral abdominal wall.
Figure 2 Post-TAP
block. ‘Doyles’ internal-bulge sign’ reflecting visible local anaesthetic infiltration into the TAP.
internally (Figs 1 and 2). The laparoscopic assisted TAP block is, in effect, a safer blind technique and cannot therefore be as reliable as ‘direct’ observation with ultrasound placement. We believe that it is a safer (and less time consuming) technique, by preventing intraperitoneal placement. The presence of an internal bulge ‘sign’ suggests that it is not too superficial, i.e. in the internal oblique muscle, as the transversus muscle is pushed away from the internal oblique muscle. Too deep needle placement, below the TAP plane, reveals the impression of a sharp needle at the peritoneum, and on injection, the peritoneum looks as though it is filling with local anaesthetic. The needle can be withdrawn slightly to produce a denting of the tissues and a fuller spread. We have found that our approach reduces the time taken to perform the block compared with the traditional ultrasound-guided technique and it is useful where ultrasound is not available. The benefits of TAP block have been demonstrated in open nephrectomy 317
Correspondence Anaesthesia, 2011, 66, pages 311–322 . ....................................................................................................................................................................................................................
with improved pain relief, accelerated discharge and reduced inpatient stay and overall cost of care [4]. Our perception is that it also reduces the opioid requirement in the laparoscopic cases. With increasing numbers of laparoscopic nephrectomy cases performed, we suggest that our technique may improve safety and save time, although formal evaluation would be required. A. Chetwood S. Agrawal D. Hrouda P. Doyle Charing Cross Hospital Imperial College NHS Healthcare Trust London, UK Email: andrewchetwood@doctors. org.uk
No external funding and no competing interests declared. Figures published with the written consent of the patient. Previously posted at the Anaesthesia Correspondence website: http://www.anaesthesiacorrespondence. com.
References 1 Finnerty O, Carney J, McDonnell JG. Trunk blocks for abdominal surgery. Anaesthesia 2010; 65(Suppl. 1): 76–83. 2 Rafi AN. Abdominal field block: a new approach via the lumbar triangle. Anaesthesia 2001; 56: 1024–6. 3 Petersen PL, Mathiesen O, Torup H, Dahl JB. The transversus abdominis plane block: a valuable option for postoperative analgesia? A topical review. Acta Anaesthesiologica Scandinavica 2010; 54: 529–35. 4 Forastiere E, Sofra M, Giannarelli D, Fabrizi L, Simone G. Effectiveness of continuous wound infusion of 0.5% ropivacaine by On-Q pain relief system for postoperative pain management after open nephrectomy. British Journal of Anaesthesia 2008; 101: 841–7. doi: 10.1111/j.1365-2044.2011.06664.x
318
Anaesthetic lubrication
We report the novel use of Propofol- Lipuro (B Braun Ltd, Melsungen, Germany) as an emergency lubricant. During the preparation of a complex emergency case, it is not uncommon for drip stands, syringe driver clamps and operating table attachments to become overtightened. These pieces of apparatus can then present unexpected problems, for example, when trying to expedite the postoperative transfer of a patient to the intensive care unit. We recently came unstuck when a metal syringe driver clamp (supporting a vital vasopressor infusion) became inseparable from the operating table drip stand. The situation was swiftly remedied and the mechanism freed by a couple of drops of Propofol-Lipuro. In attempt to establish further the formulation’s lubricant properties, we have tested it on a variety of decommissioned hospital equipment and found that it effectively reduces friction, eases movement and eliminates noise on all metal ⁄ metal interfaces. The solution’s lubricity stems from the soya bean oil (10%) and propofol (1%) emulsion necessary to create a stable formulation for injection. The use of vegetable oils as lubricants is currently undergoing a global renaissance due to concerns over supply shortages and the environmental impact of manufacturing and disposal of petroleum-based oils [1]. Relevant to our description is the use of soya bean oil emulsions in the high-speed metal working industry where experimental data have demonstrated a lower coefficient of friction than the neat oil alone [2]. Vegetable oils have several advantages over mineral oils including greater lubricity, higher viscosity index and flash ⁄ fire points. The superior viscosity index signifies that the viscosity of vegetable oils (and therefore their performance) is less affected by extremes of temperature than mineral oils. The widespread use of biodegradable lubricants is prevented by their lack of oxidative stability. However, recent advances in biotech-
nology have led to the development of genetically enhanced soya bean seeds, which produce oil with 30 times greater resistance to oxidation [3]. Fujise et al. highlighted that propofol dissolves and weakens some plastics as it was originally developed as a plasticiser and plastic additive [4]. We therefore recommend care when applying it to equipment with plastic components such as swivel chairs or squeaky trolley wheels! R. Thomas N. Wilson Broomfield Hospital, Chelmsford, Essex, UK Email:
[email protected] No external funding and no competing interests declared.
References 1 United Soybean Board. Technical Data Sheet – Soy Lubricants. http://www. unitedsoybean.org/FileDownload. aspx?fid=4110&File=38508_ TechSheet_Lubricants.pdf (accessed 02 ⁄ 12 ⁄ 2010). 2 Doll K, Sharma B. Emulsification of chemically modified vegetable oils for lubricant use. Journal of Surfactants and Detergents, May 2010; 14: 131–8. 3 Honary L. Biodegradable ⁄ Biobased Lubricants and Greases. Machinery Lubrication. September 2001. http:// www.machinerylubrication.com/ Read/240/biodegradable-biobasedlubricants (accessed 02 ⁄ 12 ⁄ 2010). 4 Fujise K, Inoue S, Okuno S, Asai T, Shingu K. Damage to a syringe pump by propofol. Anaesthesia 2005; 60: 1045–6. doi: 10.1111/j.1365-2044.2011.06675.x
Monitoring central venous pressure: proximal or distal lumen?
Alsafi et al. [1] recommend that central venous pressure (CVP) should be monitored via the proximal lumen of a central venous catheter to help detect catheter migration. We fully support this, but do not
Anaesthesia 2011 The Association of Anaesthetists of Great Britain and Ireland
