Anaesthesia 2014, 69, 511–526
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can’t ventilate algorithm into clinical practice. Anaesthesia 2009; 64: 601–8. Rai MR. The humble bougie . . . forty years and still counting? Anaesthesia 2014; 69: 199–203. Baker PA, Fernandez TMA, Hamaekers AE, Thompson JMD. Parker Flex-Tip or standard tracheal tube for percutaneous emergency airway access? Acta Anaesthesiologica Scandinavica 2013; 57: 165–70. Boon JM, Abrahams PH, Meiring JH, Welch T. Cricothyroidotomy: A clinical anatomy review. Clinical Anatomy 2004; 17: 478–86. Greenland KB, Grimmet W, Hurn H, Edwards M. Endobronchial intubation and scapel-bougie technique. Anaesthesia 2009; 64: 1269–70. doi:10.1111/anae.12695
Pooled platelet ratio in damage control resuscitation As a consultant anaesthetist who deployed twice to the Field Hospital in Camp Bastion during the time period of Morrison et al.’s retrospective study (Jul 2008 to Dec 2010), I wanted to point out that we were administering pooled platelets after every six units of pooled red blood cells (PRBCs) and fresh frozen plasma (FFP), not every five as stated in the paper [1], which explains why a median of four pools of platelets were administered for a median of 27 PRBC and FFP, rather than five. This protocol was based on a typical pool of platelets being derived from six whole blood donations, giving a 1:1:1 ratio of PRBC: FFP:platelets. The one pooled unit to five PRBC/FFP ratio may have been taken from the paper by Dawes and Thomas [2], which stated: “Using platelet apheresis in theatre. . ..we gave 1 platelet pool every 518
Correspondence
5 ‘units’ of 1:1 PRBC to FFP”. Platelet apheresis from an emergency donor panel is only used when stocks of pooled platelets from the UK are unavailable, which was not very often. It can take up to four hours from requesting apheresis platelets for their becoming available to transfuse, resulting from the cumulative time involved in finding the donor, undertaking a repeat questionnaire, apheresis time and pack preparation. During the immediate damage control resuscitation period, platelets would therefore come from UK Blood Transfusion Service pooled packs. Although the use of point-ofcare thromboelastography has allowed more individualised tailoring of haemostatic resuscitation since 2009, the initial resuscitation period is still based on one pool of platelets after six PRBC and six FFP. Indeed, thromboelastography usually confims an ongoing ratio of one pool of platelets for every 6:6 PRBC/FFP. Nevertheless, the underlying message of the article, that contemporary intra-operative resuscitation strategies can normalise the physological derangements caused by haemorrhagic shock, remains. T. Lowes James Cook University Hospital 16 Medical Regiment, Middlesbrough, 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. Morrison JJ, Ross JD, Poon H, et al. Intraoperative correction of acidosis, coagulopathy and hypothermia. Anaesthesia 2013; 68: 846–50. 2. Dawes R, Thomas GO. Battlefield resuscitation. Current Opinion in Critical Care 2009; 15: 527–35. doi:10.1111/anae.12688
Reducing postoperative delirium I read with great interest the systematic review by Moyce et al., on interventions to decrease post-operative delirium [1]. I congratulate the authors as much on their choice of subject as on the detailed work they have done. I am concerned, though, that an anomaly in their metaanalysis may have caused them to overlook a beneficial therapy. Figure 4 presents the results of a meta-analysis of studies comparing intravenous vs inhalational anaesthesia. The first study listed is ‘Cai 2012’ [2], a high-powered (n = 2000) and apparently high-quality, block-randomised, blinded controlled trial, showing a strong and statistically highly significant benefit in favour of intravenous anaesthesia. This study has been assigned a weighting of 0% in the meta-analysis, and is not represented on the adjacent Forest plot; no explanation is given for this weighting in either the figure or the text. Below it in Figure 4 is ‘Hocker 2009’, a study that appears neither in the ‘characteristics of included studies’ (Table 1), nor in the reference list. This study, of 101 patients, has been assigned a weight of 72%; not surprisingly, its result dominates the final meta-analysis,
© 2014 The Association of Anaesthetists of Great Britain and Ireland
2.
3.
4.
5.
can’t ventilate algorithm into clinical practice. Anaesthesia 2009; 64: 601–8. Rai MR. The humble bougie . . . forty years and still counting? Anaesthesia 2014; 69: 199–203. Baker PA, Fernandez TMA, Hamaekers AE, Thompson JMD. Parker Flex-Tip or standard tracheal tube for percutaneous emergency airway access? Acta Anaesthesiologica Scandinavica 2013; 57: 165–70. Boon JM, Abrahams PH, Meiring JH, Welch T. Cricothyroidotomy: A clinical anatomy review. Clinical Anatomy 2004; 17: 478–86. Greenland KB, Grimmet W, Hurn H, Edwards M. Endobronchial intubation and scapel-bougie technique. Anaesthesia 2009; 64: 1269–70. doi:10.1111/anae.12695
Pooled platelet ratio in damage control resuscitation As a consultant anaesthetist who deployed twice to the Field Hospital in Camp Bastion during the time period of Morrison et al.’s retrospective study (Jul 2008 to Dec 2010), I wanted to point out that we were administering pooled platelets after every six units of pooled red blood cells (PRBCs) and fresh frozen plasma (FFP), not every five as stated in the paper [1], which explains why a median of four pools of platelets were administered for a median of 27 PRBC and FFP, rather than five. This protocol was based on a typical pool of platelets being derived from six whole blood donations, giving a 1:1:1 ratio of PRBC: FFP:platelets. The one pooled unit to five PRBC/FFP ratio may have been taken from the paper by Dawes and Thomas [2], which stated: “Using platelet apheresis in theatre. . ..we gave 1 platelet pool every 518
Correspondence
5 ‘units’ of 1:1 PRBC to FFP”. Platelet apheresis from an emergency donor panel is only used when stocks of pooled platelets from the UK are unavailable, which was not very often. It can take up to four hours from requesting apheresis platelets for their becoming available to transfuse, resulting from the cumulative time involved in finding the donor, undertaking a repeat questionnaire, apheresis time and pack preparation. During the immediate damage control resuscitation period, platelets would therefore come from UK Blood Transfusion Service pooled packs. Although the use of point-ofcare thromboelastography has allowed more individualised tailoring of haemostatic resuscitation since 2009, the initial resuscitation period is still based on one pool of platelets after six PRBC and six FFP. Indeed, thromboelastography usually confims an ongoing ratio of one pool of platelets for every 6:6 PRBC/FFP. Nevertheless, the underlying message of the article, that contemporary intra-operative resuscitation strategies can normalise the physological derangements caused by haemorrhagic shock, remains. T. Lowes James Cook University Hospital 16 Medical Regiment, Middlesbrough, 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. Morrison JJ, Ross JD, Poon H, et al. Intraoperative correction of acidosis, coagulopathy and hypothermia. Anaesthesia 2013; 68: 846–50. 2. Dawes R, Thomas GO. Battlefield resuscitation. Current Opinion in Critical Care 2009; 15: 527–35. doi:10.1111/anae.12688
Reducing postoperative delirium I read with great interest the systematic review by Moyce et al., on interventions to decrease post-operative delirium [1]. I congratulate the authors as much on their choice of subject as on the detailed work they have done. I am concerned, though, that an anomaly in their metaanalysis may have caused them to overlook a beneficial therapy. Figure 4 presents the results of a meta-analysis of studies comparing intravenous vs inhalational anaesthesia. The first study listed is ‘Cai 2012’ [2], a high-powered (n = 2000) and apparently high-quality, block-randomised, blinded controlled trial, showing a strong and statistically highly significant benefit in favour of intravenous anaesthesia. This study has been assigned a weighting of 0% in the meta-analysis, and is not represented on the adjacent Forest plot; no explanation is given for this weighting in either the figure or the text. Below it in Figure 4 is ‘Hocker 2009’, a study that appears neither in the ‘characteristics of included studies’ (Table 1), nor in the reference list. This study, of 101 patients, has been assigned a weight of 72%; not surprisingly, its result dominates the final meta-analysis,
© 2014 The Association of Anaesthetists of Great Britain and Ireland
