Anaesthesia 2015, 70, 105–117
Correspondence
TAP block nomenclature
[2]. Unfortunately, the triangle was incorrectly illustrated in the lateral rather than posterior abdominal wall. The injection sites were also positioned laterally, particular for the subject in the CT image who received an injection centred anteriorly to the mid-axillary line. Jankovic et al. showed the anterior and middle parts of the triangle of Petit to be on average 5.8 cm and 9.3 cm posterior to the mid-axillary line, respectively [3]. As originally described, therefore, it is not possible to inject perpendicular to the triangle of Petit without rolling the patient onto his/her side. In many patients, the skin over the lumbar triangle of Petit is in contact with the mattress when positioned supine. I co-authored the first description of ultrasound-guided TAP block in 2007 [4], and was aware of McDonnell et al.’s detailed description of the triangle of Petit landmark technique at the time of
Børglum et al. propose a division of transversus abdominis plexus (TAP) block nomenclature into ‘upper’ and ‘lateral’ zones with ‘dual’ TAP blocks being injections into both zones [1]. The use of ‘posterior’ in this scheme is reserved for the injection through the triangle of Petit. Nomenclature involving the triangle of Petit in relation to abdominal wall blockade has been confused from the start. In their landmark 2007 paper, McDonnell et al. described a block via the triangle of Petit using illustrations, computed tomography (CT) and magnetic resonance images
Figure 4 Diagram of proposed TAP zones. USC, upper subcostal; LSC, lower subcostal; LAT, lateral; POST, posterior; II, ilio-inguinal.
M. John I. Ahmad Guys and St Thomas’ NHS Foundation Trust, London, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
References
1. Rai MR. The humble bougie. . .forty years and still counting? Anaesthesia 2014; 69: 199–203. 2. Amathieu R, Combes X, Abdi W, et al. An algorithm for difficult airway management, modified for modern optical devices (Airtraq laryngoscope; LMA CTrachTM): a 2-year prospective validation in patients for elective abdominal, gynecologic, and thyroid surgery. Anesthesiology 2011; 114: 25–33. doi:10.1111/anae.12947
112
writing. When it became apparent that posterior block did not spread well above the umbilicus, I described a ‘subcostal’ approach to improve spread [5], the term being used in the surgical sense as in subcostal (Kocher’s) incision, rather than in reference to the subcostal nerve. ‘Subcostal oblique’ was used to define the passage of the needle along the costal margin, enabling a catheter to be placed, producing a more extensive block across the line of the nerves. Børglum and colleagues propose that we should drop the use of ‘subcostal’ to avoid confusion with the subcostal nerve, but I do not think this a strong argument as the term has been in use in the literature for six years and correlates with the surgical anatomy. ‘Intercostal’ has also been used to refer to the subcostal location, which makes less sense since intercostal block already exists, and almost all blocks into the TAP block the inter-
© 2014 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
costal nerves even though the block is not in the intercostal space. Lee at al. first used ‘posterior’ to define a separate TAP location in 2010 when comparing the lateral site with a subcostal injection [6], more clearly locating ‘lateral’ as ‘posterior’ in this context. It is clear that location of injection into the TAP alters the spread and effect of TAP blocks. I propose the range of TAP injections should be classified as follows (Fig. 4): 1 Upper subcostal TAP (deep to the rectus, mainly covering T7 and T8) 2 Lower subcostal TAP (lateral to rectus. mainly covering T-11) 3 Lateral TAP (midway between costal margin and iliac crest in the mid-clavicular line, mainly covering T11 and T12) 4 Ilio-inguinal TAP (near the iliac crest lateral to the anterior superior iliac spine, mainly covering T12 and L1) 5 Posterior TAP (injections in the TAP in the area of the triangle of Petit) This proposed scheme describes five distinct areas that have a different distribution of blockade. Within this scheme terms such as ‘dual’ or ‘four quadrant’ TAP blocks may refer to injection into the upper subcostal and lateral areas, and ‘subcostal oblique’ to a single injection passing through the upper and lower subcostal TAP to the ilioinguinal TAP area. P. Hebbard North East Health, Wangaratta, Australia Email: [email protected]
Anaesthesia 2015, 70, 105–117
No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Børglum J, Abdallah FW, McDonnell JG, Moriggl B, Bendtsen TF. TAP block terminology. Anaesthesia 2014; 69: 1055–6. 2. McDonnell JG, O’Donnell BD, Farrell T, et al. Transversus abdominis plane block: a cadaveric and radiological evaluation. Regional Anesthesia and Pain Medicine 2007; 32: 399–404. 3. 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. 4. Hebbard P, Fujiwara Y, Shibata Y, Royse C. Ultrasound-guided transversus abdominis plane (TAP) block. Anaesthesia and Intensive Care 2007; 35: 616–7. 5. Hebbard P. Subcostal transversus abdominis plane block under ultrasound guidance. Anesthesia and Analgesia 2008; 106: 674–5. 6. Lee TH, Barrington MJ, Tran TM, Wong D, Hebbard PD. Comparison of extent of sensory block following posterior and subcostal approaches to ultrasoundguided transversus abdominis plane block. Anaesthesia and Intensive Care 2010; 38: 452–60. doi:10.1111/anae.12970
Melatonin and postoperative pain: can the heterogeneous be pooled? Andersen et al.’s systematic review suggests that peri-operative melatonin reduced postoperative pain compared with placebo, but that the magnitude of this effect suffered from substantial statistical heterogeneity [1], potential causes of which, we think, merit further discussion.
© 2014 The Association of Anaesthetists of Great Britain and Ireland
Firstly, the meta-analysis included heterogeneous surgical populations, including patients undergoing open prostatectomy, open hysterectomy, laparoscopic cholecystectomy, ophthalmological surgery and hand surgery, who may have experienced differences in operative stress and pain. Extrapolating findings from such a mixed population might be inappropriate, and might have been better considered by type of surgery instead. Secondly, the time points at which pain was measured varied across trials. For example, Ismail et al. evaluated pain in the recovery room [2], whereas Capuzzo et al. assessed pain at multiple time points until seven days postoperatively [3], during which period, barring complications, pain is likely to have diminished. It might have been more useful for readers if Anderson et al. had published the results of pooled pain scores from a predetermined and clinically relevant time point. Finally, we think that some relevant trials were excluded from the analysis. Twelve trials have investigated the analgesic effects of melatonin, eight of which were included in this meta-analysis. The four excluded trials assessed postoperative pain using a visual analogue scale (VAS) [4–7], three of which were at odds with Anderson et al.’s conclusions by reporting that pain scores showed no difference between melatonin and placebo groups [4–6], with the other not reporting a result [7]. Excluding under-reporting trials or trials with non-significant findings might render a meta-analysis subject to 113
Correspondence
TAP block nomenclature
[2]. Unfortunately, the triangle was incorrectly illustrated in the lateral rather than posterior abdominal wall. The injection sites were also positioned laterally, particular for the subject in the CT image who received an injection centred anteriorly to the mid-axillary line. Jankovic et al. showed the anterior and middle parts of the triangle of Petit to be on average 5.8 cm and 9.3 cm posterior to the mid-axillary line, respectively [3]. As originally described, therefore, it is not possible to inject perpendicular to the triangle of Petit without rolling the patient onto his/her side. In many patients, the skin over the lumbar triangle of Petit is in contact with the mattress when positioned supine. I co-authored the first description of ultrasound-guided TAP block in 2007 [4], and was aware of McDonnell et al.’s detailed description of the triangle of Petit landmark technique at the time of
Børglum et al. propose a division of transversus abdominis plexus (TAP) block nomenclature into ‘upper’ and ‘lateral’ zones with ‘dual’ TAP blocks being injections into both zones [1]. The use of ‘posterior’ in this scheme is reserved for the injection through the triangle of Petit. Nomenclature involving the triangle of Petit in relation to abdominal wall blockade has been confused from the start. In their landmark 2007 paper, McDonnell et al. described a block via the triangle of Petit using illustrations, computed tomography (CT) and magnetic resonance images
Figure 4 Diagram of proposed TAP zones. USC, upper subcostal; LSC, lower subcostal; LAT, lateral; POST, posterior; II, ilio-inguinal.
M. John I. Ahmad Guys and St Thomas’ NHS Foundation Trust, London, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com.
References
1. Rai MR. The humble bougie. . .forty years and still counting? Anaesthesia 2014; 69: 199–203. 2. Amathieu R, Combes X, Abdi W, et al. An algorithm for difficult airway management, modified for modern optical devices (Airtraq laryngoscope; LMA CTrachTM): a 2-year prospective validation in patients for elective abdominal, gynecologic, and thyroid surgery. Anesthesiology 2011; 114: 25–33. doi:10.1111/anae.12947
112
writing. When it became apparent that posterior block did not spread well above the umbilicus, I described a ‘subcostal’ approach to improve spread [5], the term being used in the surgical sense as in subcostal (Kocher’s) incision, rather than in reference to the subcostal nerve. ‘Subcostal oblique’ was used to define the passage of the needle along the costal margin, enabling a catheter to be placed, producing a more extensive block across the line of the nerves. Børglum and colleagues propose that we should drop the use of ‘subcostal’ to avoid confusion with the subcostal nerve, but I do not think this a strong argument as the term has been in use in the literature for six years and correlates with the surgical anatomy. ‘Intercostal’ has also been used to refer to the subcostal location, which makes less sense since intercostal block already exists, and almost all blocks into the TAP block the inter-
© 2014 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
costal nerves even though the block is not in the intercostal space. Lee at al. first used ‘posterior’ to define a separate TAP location in 2010 when comparing the lateral site with a subcostal injection [6], more clearly locating ‘lateral’ as ‘posterior’ in this context. It is clear that location of injection into the TAP alters the spread and effect of TAP blocks. I propose the range of TAP injections should be classified as follows (Fig. 4): 1 Upper subcostal TAP (deep to the rectus, mainly covering T7 and T8) 2 Lower subcostal TAP (lateral to rectus. mainly covering T-11) 3 Lateral TAP (midway between costal margin and iliac crest in the mid-clavicular line, mainly covering T11 and T12) 4 Ilio-inguinal TAP (near the iliac crest lateral to the anterior superior iliac spine, mainly covering T12 and L1) 5 Posterior TAP (injections in the TAP in the area of the triangle of Petit) This proposed scheme describes five distinct areas that have a different distribution of blockade. Within this scheme terms such as ‘dual’ or ‘four quadrant’ TAP blocks may refer to injection into the upper subcostal and lateral areas, and ‘subcostal oblique’ to a single injection passing through the upper and lower subcostal TAP to the ilioinguinal TAP area. P. Hebbard North East Health, Wangaratta, Australia Email: [email protected]
Anaesthesia 2015, 70, 105–117
No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Børglum J, Abdallah FW, McDonnell JG, Moriggl B, Bendtsen TF. TAP block terminology. Anaesthesia 2014; 69: 1055–6. 2. McDonnell JG, O’Donnell BD, Farrell T, et al. Transversus abdominis plane block: a cadaveric and radiological evaluation. Regional Anesthesia and Pain Medicine 2007; 32: 399–404. 3. 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. 4. Hebbard P, Fujiwara Y, Shibata Y, Royse C. Ultrasound-guided transversus abdominis plane (TAP) block. Anaesthesia and Intensive Care 2007; 35: 616–7. 5. Hebbard P. Subcostal transversus abdominis plane block under ultrasound guidance. Anesthesia and Analgesia 2008; 106: 674–5. 6. Lee TH, Barrington MJ, Tran TM, Wong D, Hebbard PD. Comparison of extent of sensory block following posterior and subcostal approaches to ultrasoundguided transversus abdominis plane block. Anaesthesia and Intensive Care 2010; 38: 452–60. doi:10.1111/anae.12970
Melatonin and postoperative pain: can the heterogeneous be pooled? Andersen et al.’s systematic review suggests that peri-operative melatonin reduced postoperative pain compared with placebo, but that the magnitude of this effect suffered from substantial statistical heterogeneity [1], potential causes of which, we think, merit further discussion.
© 2014 The Association of Anaesthetists of Great Britain and Ireland
Firstly, the meta-analysis included heterogeneous surgical populations, including patients undergoing open prostatectomy, open hysterectomy, laparoscopic cholecystectomy, ophthalmological surgery and hand surgery, who may have experienced differences in operative stress and pain. Extrapolating findings from such a mixed population might be inappropriate, and might have been better considered by type of surgery instead. Secondly, the time points at which pain was measured varied across trials. For example, Ismail et al. evaluated pain in the recovery room [2], whereas Capuzzo et al. assessed pain at multiple time points until seven days postoperatively [3], during which period, barring complications, pain is likely to have diminished. It might have been more useful for readers if Anderson et al. had published the results of pooled pain scores from a predetermined and clinically relevant time point. Finally, we think that some relevant trials were excluded from the analysis. Twelve trials have investigated the analgesic effects of melatonin, eight of which were included in this meta-analysis. The four excluded trials assessed postoperative pain using a visual analogue scale (VAS) [4–7], three of which were at odds with Anderson et al.’s conclusions by reporting that pain scores showed no difference between melatonin and placebo groups [4–6], with the other not reporting a result [7]. Excluding under-reporting trials or trials with non-significant findings might render a meta-analysis subject to 113
