Anaesthesia 2013, 68, 1274–1287
for the fact that the latter is primarily a high-volume block [2]. One advantage of fascia iliaca block over nerve stimulator-guided femoral nerve block is that stimulation of the leg muscles causes discomfort to the patient and may affect the fracture alignment. Using ultrasound guidance negates the need for a nerve stimulator and may increase the success rate for both blocks [2]. However, in most UK hospitals, these blocks are performed by non-anaesthetists, who are unlikely to have the necessary skills [3]. The AAGBI/RA-UK’s recent position statement [4], stating that fascia iliaca block can be considered as a ‘local anaesthetic’ and not a ‘regional anaesthetic’ technique, paves the way for appropriately trained non-physician practitioners to perform this block in patients with proximal femoral fractures. S. Adyanthaya A. Rashid Bedford Hospital NHS Trust Bedford, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Newman B, McCarthy L, Thomas PW, May P, Layzell M, Horn K. A comparison of pre-operative nerve stimulatorguided femoral nerve block and fascia iliaca compartment block in patients with a femoral neck fracture. Anaesthesia 2013; 68: 899–903. 2. Marhofer P, Harrop-Griffiths H, Willschke H, Kirchmair L. Fifteen years of ultra1280
Correspondence sound guidance in regional anaesthesia: Part 2—Recent developments in block techniques. British Journal of Anaesthesia 2010; 104: 673–83. 3. Rashid A, Beswick E, Galitzine S, Fitton L. Regional analgesia in the emergency department for hip fractures: survey of current UK practice and its impact on services in a teaching hospital. Emergency Medicine Journal 2013 Jul 22; doi: 10.1136/emermed-2013-202794. 4. Association of Anaesthetists of Great Britain & Ireland/Regional Anaesthesia-UK. Fascia iliaca blocks and non-physician practitioners. AAGBI position statement 2013. http://www.aagbi.org/sites/default/ files/Fascia%20Ilaica%20statement%2022 JAN2013.pdf (accessed 23/09/2013). doi:10.1111/anae.12501
Peri-operative fitness: a question of stamina? We read with interest two articles about pre-operative exercise tests. Lee et al. [1] analysed data on sixminute walk tests from a previous study [2]. They suggested the test could provide prognostic information. We were also drawn to the eloquent editorial by Carlisle and further re-analysis of the same data [3]. So, does the distance a patient can walk in six minutes help the anaesthetist? We would like to raise issues about the original data and question what type of fitness a patient may need for surgery. The original study [2] was designed to examine changes in the six-minute walk test following exercise ‘prehabilitation’. The control group (recommended to walk daily and perform ankle and breathing exercises) outperformed the exercise intervention group. Excluded from this were patients who could not complete the exercise programme or exercise tests; therefore, most
(79%) patients included were of ASA physical status 1-2. This same data were then analysed retrospectively by Lee et al. Surely this patient group is not the intended population for a pre-operative fitness test? Lee et al. looked at whether complications following various colorectal procedures for benign disease could be predicted by performance in the walk test done as part of the prehabiliation study. This analysis showed that patients who could walk further had fewer complications and this was the basis of re-analysis by Carlisle. However, the original data also showed that older patients had fewer complications. This could not be explained and is counter-intuitive. Even the elegant statistical reanalysis by Carlisle failed to show that a walk test correlated with outcomes. In such a mixed group this is not a surprise to us. We know that for these types of studies to predict outcomes reliably, large patient numbers are required [4, 5]. Both surgical and anaesthetic factors also need to be taken into account, and the analysis should seek to detect an inflexion point or threshold rather than modelling a straight-line process. If patients are fit enough to walk 600 m then they are probably at no higher risk than someone able to walk 800 m in six minutes. A debate about a finite number of heartbeats does not help us decide the role of pre-operative exercise testing or the particular role of a low-tech walk test or full ergonometric assessments. Although all our experience suggests being fit
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
for surgery is vital, exactly why a cardiorespiratory reserve matters is still uncharted. With good anaesthesia, cardiovascular demands can be maintained at near resting levels. So is fitness more a question of stamina and the ability to maintain a moderately raised cardiac output for a period of 48–72 hours to cope with fluid shifts, lower haematocrit and the metabolic sequelae of surgery? If so, which pre-operative test correlates best with stamina? The evidence we have points to the lactate threshold rather than maximal oxygen consumption but other indicators, such as duration and recovery speed, could contribute if the testing is performed according to a standard protocol. B. Spooner G. Fisher Russells Hall Hospital Dudley, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Lee L, Schwartzman K, Carli F, et al. The association of the distance walked in six minutes with pre operative peak oxygen consumption and complications one month after colorectal resection. Anaesthesia 2013; 68: 811–6. 2. Carli F, Charlebois P, Stein B, et al. Randomized clinical trial of prehabilitation in colorectal surgery. British Journal of Surgery 2010; 97: 1187–97. 3. Carlisle JB. The quick and the dead. Anaesthesia 2013; 68: 8. 4. Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. Euro-
Anaesthesia 2013, 68, 1274–1287 pean system for cardiac operative risk evaluation (EuroSCORE). European Journal of Cardiothoracic Surgery 1999; 16: 9–13. 5. Prytherch DR, Whiteley MS, Higgins B, Weaver PC, Prout WG, Powell SJ. POSSUM and Portsmouth POSSUM for predicting mortality. Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity. British Journal of Surgery 1998; 85: 1217–20. doi:10.1111/anae.12473
A reply I thank Drs Spooner and Fisher for their comments on the article by Lee et al. [1] and my editorial [2], and will respond to those related to the latter. My first response is to correct their assertion that I re-analysed the association of distance walked with outcomes: I did not. I did re-analyse the association of distance walked with peak oxygen consumption whilst pedalling. I suggested there might be too much ‘noise’ to determine one from the other. However, this does not discount the possibility that the association of both with postoperative outcomes might be similar. I agree with Spooner and Fisher that the relationships between fitness and outcomes will not be linear. Certainly, the interaction of fitness with other prognostic variables precludes the prediction of outcomes using this or any other single variable. I therefore do not agree with their belief that there is a ‘special’ threshold along the continuum of fitness that separates
© 2013 The Association of Anaesthetists of Great Britain and Ireland
those who experience an event from those who do not, whether the continuum is oxygen consumption or distance walked. Threshold values reported from ROC curve analyses are not exclusive: either side of the value there remains a relationship between the continuous variable and the categorical outcome. I extended the discussion of fitness from the narrow considerations of the pre-operative clinic to ageing and evolution. My purpose was not trivial: I believe that discursion beyond what one might consider relevant can generate ideas that lead to advances that a more limited view would fail to see. Spooner and Fisher assume that the association between fitness and outcome is causative and suggest mechanisms that might mediate this effect. Their suggestions will be acceptably familiar to many anaesthetists. I raised the possibility that this assumption of a causative relationship is, at least in part, incorrect. J. B. Carlisle Torbay Hospital Devon, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Lee L, Schwartzman K, Carli F, et al. The association of the distance walked in six minutes with pre-operative peak oxygen consumption and complications one month after colorectal resection. Anaesthesia 2013; 68: 811–6.
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for the fact that the latter is primarily a high-volume block [2]. One advantage of fascia iliaca block over nerve stimulator-guided femoral nerve block is that stimulation of the leg muscles causes discomfort to the patient and may affect the fracture alignment. Using ultrasound guidance negates the need for a nerve stimulator and may increase the success rate for both blocks [2]. However, in most UK hospitals, these blocks are performed by non-anaesthetists, who are unlikely to have the necessary skills [3]. The AAGBI/RA-UK’s recent position statement [4], stating that fascia iliaca block can be considered as a ‘local anaesthetic’ and not a ‘regional anaesthetic’ technique, paves the way for appropriately trained non-physician practitioners to perform this block in patients with proximal femoral fractures. S. Adyanthaya A. Rashid Bedford Hospital NHS Trust Bedford, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Newman B, McCarthy L, Thomas PW, May P, Layzell M, Horn K. A comparison of pre-operative nerve stimulatorguided femoral nerve block and fascia iliaca compartment block in patients with a femoral neck fracture. Anaesthesia 2013; 68: 899–903. 2. Marhofer P, Harrop-Griffiths H, Willschke H, Kirchmair L. Fifteen years of ultra1280
Correspondence sound guidance in regional anaesthesia: Part 2—Recent developments in block techniques. British Journal of Anaesthesia 2010; 104: 673–83. 3. Rashid A, Beswick E, Galitzine S, Fitton L. Regional analgesia in the emergency department for hip fractures: survey of current UK practice and its impact on services in a teaching hospital. Emergency Medicine Journal 2013 Jul 22; doi: 10.1136/emermed-2013-202794. 4. Association of Anaesthetists of Great Britain & Ireland/Regional Anaesthesia-UK. Fascia iliaca blocks and non-physician practitioners. AAGBI position statement 2013. http://www.aagbi.org/sites/default/ files/Fascia%20Ilaica%20statement%2022 JAN2013.pdf (accessed 23/09/2013). doi:10.1111/anae.12501
Peri-operative fitness: a question of stamina? We read with interest two articles about pre-operative exercise tests. Lee et al. [1] analysed data on sixminute walk tests from a previous study [2]. They suggested the test could provide prognostic information. We were also drawn to the eloquent editorial by Carlisle and further re-analysis of the same data [3]. So, does the distance a patient can walk in six minutes help the anaesthetist? We would like to raise issues about the original data and question what type of fitness a patient may need for surgery. The original study [2] was designed to examine changes in the six-minute walk test following exercise ‘prehabilitation’. The control group (recommended to walk daily and perform ankle and breathing exercises) outperformed the exercise intervention group. Excluded from this were patients who could not complete the exercise programme or exercise tests; therefore, most
(79%) patients included were of ASA physical status 1-2. This same data were then analysed retrospectively by Lee et al. Surely this patient group is not the intended population for a pre-operative fitness test? Lee et al. looked at whether complications following various colorectal procedures for benign disease could be predicted by performance in the walk test done as part of the prehabiliation study. This analysis showed that patients who could walk further had fewer complications and this was the basis of re-analysis by Carlisle. However, the original data also showed that older patients had fewer complications. This could not be explained and is counter-intuitive. Even the elegant statistical reanalysis by Carlisle failed to show that a walk test correlated with outcomes. In such a mixed group this is not a surprise to us. We know that for these types of studies to predict outcomes reliably, large patient numbers are required [4, 5]. Both surgical and anaesthetic factors also need to be taken into account, and the analysis should seek to detect an inflexion point or threshold rather than modelling a straight-line process. If patients are fit enough to walk 600 m then they are probably at no higher risk than someone able to walk 800 m in six minutes. A debate about a finite number of heartbeats does not help us decide the role of pre-operative exercise testing or the particular role of a low-tech walk test or full ergonometric assessments. Although all our experience suggests being fit
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
for surgery is vital, exactly why a cardiorespiratory reserve matters is still uncharted. With good anaesthesia, cardiovascular demands can be maintained at near resting levels. So is fitness more a question of stamina and the ability to maintain a moderately raised cardiac output for a period of 48–72 hours to cope with fluid shifts, lower haematocrit and the metabolic sequelae of surgery? If so, which pre-operative test correlates best with stamina? The evidence we have points to the lactate threshold rather than maximal oxygen consumption but other indicators, such as duration and recovery speed, could contribute if the testing is performed according to a standard protocol. B. Spooner G. Fisher Russells Hall Hospital Dudley, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Lee L, Schwartzman K, Carli F, et al. The association of the distance walked in six minutes with pre operative peak oxygen consumption and complications one month after colorectal resection. Anaesthesia 2013; 68: 811–6. 2. Carli F, Charlebois P, Stein B, et al. Randomized clinical trial of prehabilitation in colorectal surgery. British Journal of Surgery 2010; 97: 1187–97. 3. Carlisle JB. The quick and the dead. Anaesthesia 2013; 68: 8. 4. Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. Euro-
Anaesthesia 2013, 68, 1274–1287 pean system for cardiac operative risk evaluation (EuroSCORE). European Journal of Cardiothoracic Surgery 1999; 16: 9–13. 5. Prytherch DR, Whiteley MS, Higgins B, Weaver PC, Prout WG, Powell SJ. POSSUM and Portsmouth POSSUM for predicting mortality. Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity. British Journal of Surgery 1998; 85: 1217–20. doi:10.1111/anae.12473
A reply I thank Drs Spooner and Fisher for their comments on the article by Lee et al. [1] and my editorial [2], and will respond to those related to the latter. My first response is to correct their assertion that I re-analysed the association of distance walked with outcomes: I did not. I did re-analyse the association of distance walked with peak oxygen consumption whilst pedalling. I suggested there might be too much ‘noise’ to determine one from the other. However, this does not discount the possibility that the association of both with postoperative outcomes might be similar. I agree with Spooner and Fisher that the relationships between fitness and outcomes will not be linear. Certainly, the interaction of fitness with other prognostic variables precludes the prediction of outcomes using this or any other single variable. I therefore do not agree with their belief that there is a ‘special’ threshold along the continuum of fitness that separates
© 2013 The Association of Anaesthetists of Great Britain and Ireland
those who experience an event from those who do not, whether the continuum is oxygen consumption or distance walked. Threshold values reported from ROC curve analyses are not exclusive: either side of the value there remains a relationship between the continuous variable and the categorical outcome. I extended the discussion of fitness from the narrow considerations of the pre-operative clinic to ageing and evolution. My purpose was not trivial: I believe that discursion beyond what one might consider relevant can generate ideas that lead to advances that a more limited view would fail to see. Spooner and Fisher assume that the association between fitness and outcome is causative and suggest mechanisms that might mediate this effect. Their suggestions will be acceptably familiar to many anaesthetists. I raised the possibility that this assumption of a causative relationship is, at least in part, incorrect. J. B. Carlisle Torbay Hospital Devon, UK Email: [email protected] No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Lee L, Schwartzman K, Carli F, et al. The association of the distance walked in six minutes with pre-operative peak oxygen consumption and complications one month after colorectal resection. Anaesthesia 2013; 68: 811–6.
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