Anaesthesia 2015, 70, 361–372
References 1. Hebbard P. TAP block nomenclature. Anaesthesia 2014; 69: 112–3. 2. Børglum J, Jensen K, Christensen AF, et al. Distribution patterns, dermatomal anesthesia and ropivacaine serum concentrations after bilateral dual transversus abdominis plane block. Regional Anesthesia and Pain Medicine 2012; 37: 294–301. 3. Rozen WM, Tran TM, Ashton MW, Barrington MJ, Ivanusic JJ, Taylor GI. Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall. Clinical Anatomy 2008; 21: 325–33. 4. Jankovic ZB, du Feu FM, McConnell P. An anatomical study of the transversus abdominis plane block: location of the lumbar triangle of Petit and adjacent nerves. Anesthesia and Analgesia 2009; 109: 981–5. 5. Børglum J, Maschmann C, Belhage B, Jensen K. Ultrasound-guided bilateral dual transversus abdominis plane block: a new four-point approach. Acta Anaesthesiologica Scandinavica 2011; 55: 658–63. 6. Carney J, Finnerty O, Rauf J, Bergin D, Laffey JG, McDonnell JG. Studies on the spread of local anaesthetic solution in transversus abdominis plane blocks. Anaesthesia 2011; 66: 1023–30. 7. Lee TH, Barrington MJ, Tran TM, Wong D, Hebbard PD. Comparison of extent of sensory block following posterior and subcostal approaches to ultrasound-guided transversus abdominis plane block. Anaesthesia and Intensive Care 2010; 38: 452–60. 8. Milan Z, Tabor D, McConnell P, Pickering J, Kocarev M, du Feu F, Barton S. Three different approaches to transversus abdominis plane block: a cadaveric study. Medicinski Glasnik 2011; 8: 181–4. 9. Mitchell AU, Torup H, Hansen EG, et al. Effective dermatomal blockade after subcostal transversus abdominis plane block. Danish Medical Journal 2012; 59: A4404. doi:10.1111/anae.13023
Teaching novice anaesthetists An ‘imprecise idea’ about clinical anaesthesia in the general population of healthcare professionals is not just 370
Correspondence
confined to the Indian subcontinent [1]. During the past ten years as an anaesthetic consultant, first in the East Midlands, then the South West of England and now the South West of Scotland, I have found many staff to be vague on the objectives of anaesthesia when asked. A need to be unconscious, unaware or pain-free are the common answers. Whilst worthy objectives, I have never felt that they really get to the heart of the matter or cover all of the many areas anaesthesia is practised. A venerable ophthalmologist, lamenting the rise in popularity of orbital blocks, once challenged me: “The problem is that you anaesthetists don’t give enough **** anaesthetics any more!” I have always felt he was somewhat missing the point of my endeavours. For some years, I too have used the model of patient, surgeon and anaesthetist with their different hypothetical requirements. However, I use this as a vehicle to introduce the ‘triad of anaesthesia’, as a way into discussing the pharmacology of a balanced general anaesthetic. As for the ‘core principles of anaesthesia’, it is my opinion that they can be divided into the following three objectives: i) Preventing psychological trauma: this might simply be holding someone’s hand during surgery under regional blockade, good attention to peri-operative analgesia, or from the oblivion of general anaesthesia. We all strive to calm and reassure our patients, but the recent NAP5 [2] report has
shown how easily psychological trauma can be caused; ii) Preventing unnecessary physical trauma – ‘unnecessary’ as surgery is, by its very nature, a controlled physical trauma. However, most of what we do in anaesthesia removes the many protective mechanisms and reflexes that our patients have spent some 65 million years evolving. So while I can only do so much about where my surgical colleague chooses to cut, I am obliged not to ‘add insult to injury’ in what can be a complex and dangerous envionment; iii) Physiological manipulation to facilitate the technical tasks of surgery, by simply ensuring that the tissue to be operated on does not move too much, by altering the blood flow to an organ, or by allowing access to various body compartments through positioning and relaxation. It is very difficult to sum up what was once called ‘the dark art’ of anaesthesia in any pithy principles, but I too have had good feedback and hope that these might help illuminate some of what we do to the uninitiated. I. Anderson University Hospital Crosshouse, Kilmarnock, UK Email: [email protected] No external funding and no conflict of interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
© 2015 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
Anaesthesia 2015, 70, 361–372
References 1. Saikia P. Teaching novice anaesthetists. Anaesthesia 2014; 69: 1407. 2. Cook TM, Andrade J, Bogod DG, et al. The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: patient experiences, human factors, sedation, consent and medicolegal issues. Anaesthesia 2014; 69: 1102–16. doi:10.1111/anae.13022
Laryngeal cuff pressure – a recoil equilibrium technique We agree with the editorial by Bick et al. recommending routine manometry as the standard of care after laryngeal mask airway (LMA) insertion [1]. We have developed a second technique that helps to avoid high LMA cuff pressure [2], using the inflating syringe safety valve idea proposed by Rice et al. [3], which relies on the high pressure in an overinflated LMA cuff’s pushing out the plunger of a 20-ml BD PlastipakTM syringe (Becton, Dickinson and Co. Ltd, Oxford, England), referred to by Rice et al. as the equilibrium recoil pressure. This technique involves a five-step process: 1) insert LMA; 2) inflate cuff and check adequacy of airway seal; 3) allow LMA cuff to expel excess volume back into syringe. If the LMA cuff pressure is insufficient to push back plunger, insert more air; 4) remove a further 1 ml cuff air once equilibration recoil is reached;
5) measure cuff pressure and re-check adequacy of airway seal. This sequence is repeated as necessary to account for intraoperative cuff pressure changes, for example, due to warming of the cuff air. Knowledge of the starting cuff pressure is not necessary and the sequence is easy and quick to perform consistently. We do not advocate this as an alternative to LMA cuff pressure monitoring, but we would encourage anaesthetists to try it as opposed to relying on any ‘best guess’ method. A. Spence S. Avery C. Smith St Richard’s Hospital, Chichester, UK Email: [email protected]. uk No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
References 1. Bick E, Bailes I, Patel A, Brain AIJ. Fewer sore throats and a better seal: why routine manometry for laryngeal mask airways must become a standard of care. Anaesthesia 2014; 69: 1304–8. 2. Spence N, Smith C. Laryngeal mask airway cuff pressure reduction using a simple syringe maneuvre. Journal of One-Day Surgery 2013; 23: s31. 3. Rice M, Gravenstein NL, Brull S, Morey T, Gravenstein N. Using the inflating syringe as a safety valve to limit laryngeal mask pressure. Journal of Clinical Monitoring and Computing 2011; 25: 405–10.
© 2015 The Association of Anaesthetists of Great Britain and Ireland
doi:10.1111/anae.13024
Disposable C-MACâ – not the same but same enough We read with interest the letter by Greenland, expressing the view that the disposable C-MACâ videolaryngoscope blade (Karl Storz, Tuttlingen, Germany) was not the same as the re-usable blade, and thought we might share our experience of the disposable blade [1]. Anaesthetists are becoming more skillful with the technique of videolaryngoscopy and it could soon become standard procedure for patients with a known or suspected difficult airway [2], particularly given the risk of transmission of infection between patients when re-using blades [3]. The challenge remains to reproduce the same quality of equipment, but using different materials. We agree that the blade is not the same as the re-usable one but disagree with a few of the comments made by Greenland. Firstly, the comment made regarding the need for a more thickened plastic version of the blade to avoid breakage has been supported by a reference for a completely different product, the GlideScopeâ (GVLâ, Verathon, USA), which uses a different polymer with a different tensile strength. Greenland notes a ‘marked thickening’ of the plastic version, but no measurements are given. We have examined the dimensions of MAC-3 and -4 disposable blades, but have found these to be only 2.4 and 2.8 mm thicker at the outlet than the equivalent metal blade. Furthermore, any harmful effect of a thicker blade is
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References 1. Hebbard P. TAP block nomenclature. Anaesthesia 2014; 69: 112–3. 2. Børglum J, Jensen K, Christensen AF, et al. Distribution patterns, dermatomal anesthesia and ropivacaine serum concentrations after bilateral dual transversus abdominis plane block. Regional Anesthesia and Pain Medicine 2012; 37: 294–301. 3. Rozen WM, Tran TM, Ashton MW, Barrington MJ, Ivanusic JJ, Taylor GI. Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall. Clinical Anatomy 2008; 21: 325–33. 4. Jankovic ZB, du Feu FM, McConnell P. An anatomical study of the transversus abdominis plane block: location of the lumbar triangle of Petit and adjacent nerves. Anesthesia and Analgesia 2009; 109: 981–5. 5. Børglum J, Maschmann C, Belhage B, Jensen K. Ultrasound-guided bilateral dual transversus abdominis plane block: a new four-point approach. Acta Anaesthesiologica Scandinavica 2011; 55: 658–63. 6. Carney J, Finnerty O, Rauf J, Bergin D, Laffey JG, McDonnell JG. Studies on the spread of local anaesthetic solution in transversus abdominis plane blocks. Anaesthesia 2011; 66: 1023–30. 7. Lee TH, Barrington MJ, Tran TM, Wong D, Hebbard PD. Comparison of extent of sensory block following posterior and subcostal approaches to ultrasound-guided transversus abdominis plane block. Anaesthesia and Intensive Care 2010; 38: 452–60. 8. Milan Z, Tabor D, McConnell P, Pickering J, Kocarev M, du Feu F, Barton S. Three different approaches to transversus abdominis plane block: a cadaveric study. Medicinski Glasnik 2011; 8: 181–4. 9. Mitchell AU, Torup H, Hansen EG, et al. Effective dermatomal blockade after subcostal transversus abdominis plane block. Danish Medical Journal 2012; 59: A4404. doi:10.1111/anae.13023
Teaching novice anaesthetists An ‘imprecise idea’ about clinical anaesthesia in the general population of healthcare professionals is not just 370
Correspondence
confined to the Indian subcontinent [1]. During the past ten years as an anaesthetic consultant, first in the East Midlands, then the South West of England and now the South West of Scotland, I have found many staff to be vague on the objectives of anaesthesia when asked. A need to be unconscious, unaware or pain-free are the common answers. Whilst worthy objectives, I have never felt that they really get to the heart of the matter or cover all of the many areas anaesthesia is practised. A venerable ophthalmologist, lamenting the rise in popularity of orbital blocks, once challenged me: “The problem is that you anaesthetists don’t give enough **** anaesthetics any more!” I have always felt he was somewhat missing the point of my endeavours. For some years, I too have used the model of patient, surgeon and anaesthetist with their different hypothetical requirements. However, I use this as a vehicle to introduce the ‘triad of anaesthesia’, as a way into discussing the pharmacology of a balanced general anaesthetic. As for the ‘core principles of anaesthesia’, it is my opinion that they can be divided into the following three objectives: i) Preventing psychological trauma: this might simply be holding someone’s hand during surgery under regional blockade, good attention to peri-operative analgesia, or from the oblivion of general anaesthesia. We all strive to calm and reassure our patients, but the recent NAP5 [2] report has
shown how easily psychological trauma can be caused; ii) Preventing unnecessary physical trauma – ‘unnecessary’ as surgery is, by its very nature, a controlled physical trauma. However, most of what we do in anaesthesia removes the many protective mechanisms and reflexes that our patients have spent some 65 million years evolving. So while I can only do so much about where my surgical colleague chooses to cut, I am obliged not to ‘add insult to injury’ in what can be a complex and dangerous envionment; iii) Physiological manipulation to facilitate the technical tasks of surgery, by simply ensuring that the tissue to be operated on does not move too much, by altering the blood flow to an organ, or by allowing access to various body compartments through positioning and relaxation. It is very difficult to sum up what was once called ‘the dark art’ of anaesthesia in any pithy principles, but I too have had good feedback and hope that these might help illuminate some of what we do to the uninitiated. I. Anderson University Hospital Crosshouse, Kilmarnock, UK Email: [email protected] No external funding and no conflict of interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
© 2015 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
Anaesthesia 2015, 70, 361–372
References 1. Saikia P. Teaching novice anaesthetists. Anaesthesia 2014; 69: 1407. 2. Cook TM, Andrade J, Bogod DG, et al. The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: patient experiences, human factors, sedation, consent and medicolegal issues. Anaesthesia 2014; 69: 1102–16. doi:10.1111/anae.13022
Laryngeal cuff pressure – a recoil equilibrium technique We agree with the editorial by Bick et al. recommending routine manometry as the standard of care after laryngeal mask airway (LMA) insertion [1]. We have developed a second technique that helps to avoid high LMA cuff pressure [2], using the inflating syringe safety valve idea proposed by Rice et al. [3], which relies on the high pressure in an overinflated LMA cuff’s pushing out the plunger of a 20-ml BD PlastipakTM syringe (Becton, Dickinson and Co. Ltd, Oxford, England), referred to by Rice et al. as the equilibrium recoil pressure. This technique involves a five-step process: 1) insert LMA; 2) inflate cuff and check adequacy of airway seal; 3) allow LMA cuff to expel excess volume back into syringe. If the LMA cuff pressure is insufficient to push back plunger, insert more air; 4) remove a further 1 ml cuff air once equilibration recoil is reached;
5) measure cuff pressure and re-check adequacy of airway seal. This sequence is repeated as necessary to account for intraoperative cuff pressure changes, for example, due to warming of the cuff air. Knowledge of the starting cuff pressure is not necessary and the sequence is easy and quick to perform consistently. We do not advocate this as an alternative to LMA cuff pressure monitoring, but we would encourage anaesthetists to try it as opposed to relying on any ‘best guess’ method. A. Spence S. Avery C. Smith St Richard’s Hospital, Chichester, UK Email: [email protected]. uk No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
References 1. Bick E, Bailes I, Patel A, Brain AIJ. Fewer sore throats and a better seal: why routine manometry for laryngeal mask airways must become a standard of care. Anaesthesia 2014; 69: 1304–8. 2. Spence N, Smith C. Laryngeal mask airway cuff pressure reduction using a simple syringe maneuvre. Journal of One-Day Surgery 2013; 23: s31. 3. Rice M, Gravenstein NL, Brull S, Morey T, Gravenstein N. Using the inflating syringe as a safety valve to limit laryngeal mask pressure. Journal of Clinical Monitoring and Computing 2011; 25: 405–10.
© 2015 The Association of Anaesthetists of Great Britain and Ireland
doi:10.1111/anae.13024
Disposable C-MACâ – not the same but same enough We read with interest the letter by Greenland, expressing the view that the disposable C-MACâ videolaryngoscope blade (Karl Storz, Tuttlingen, Germany) was not the same as the re-usable blade, and thought we might share our experience of the disposable blade [1]. Anaesthetists are becoming more skillful with the technique of videolaryngoscopy and it could soon become standard procedure for patients with a known or suspected difficult airway [2], particularly given the risk of transmission of infection between patients when re-using blades [3]. The challenge remains to reproduce the same quality of equipment, but using different materials. We agree that the blade is not the same as the re-usable one but disagree with a few of the comments made by Greenland. Firstly, the comment made regarding the need for a more thickened plastic version of the blade to avoid breakage has been supported by a reference for a completely different product, the GlideScopeâ (GVLâ, Verathon, USA), which uses a different polymer with a different tensile strength. Greenland notes a ‘marked thickening’ of the plastic version, but no measurements are given. We have examined the dimensions of MAC-3 and -4 disposable blades, but have found these to be only 2.4 and 2.8 mm thicker at the outlet than the equivalent metal blade. Furthermore, any harmful effect of a thicker blade is
371
