We would like to commend Adhikary et al. for their continued efforts to show benefit from novel regional techniques for chest trauma [1], and agree that patients with rib fracture(s) have significantly improved pain scores after regional analgesia. We would like to invite the authors to reply to a number of comments that we have about their work.

Firstly, the authors make several comments about the technically challenging nature of paravertebral blockade. In our institution, ultrasound-guided thoracic paravertebral blockade is the regional technique of choice in unilateral chest trauma. Data from our experiences reveal an extremely low complication rate, with no significant complications from 314 paravertebral catheters over a four year period [1], inserted by consultant and registrar anaesthetists. This is consistent with our experience of thousands of single-shot blocks performed for breast surgery, and with similar experiences in other centres worldwide [2]. We recognise that there is, undoubtedly, a learning curve associated with the paravertebral technique, but we believe this is similar in appearance to learning curves for any other new regional anaesthetic technique.

Secondly, we note that only 79 patients were administered an erector spinae plane (ESP) block over 19 months. Can we ask whether there were other patients in the authors' institution that received epidural or paravertebral blockade during this time, and whether comparative analysis has been possible? We are not aware of any published evidence that the ESP block is technically easier, and the results of any such analysis would be useful to know when organising training. Are there novices or non-anaesthetists performing the ESP block at the authors' institution?

Thirdly, the authors question the feasibility of paravertebral blockade in coagulopathy and haemodynamic instability. In our opinion, neither coagulopathy nor anticoagulation is a contraindication to paravertebral techniques, necessarily. We assess each case individually, in line with the collaborative guideline from the AAGBI, OAA and RA-UK on regional anaesthesia techniques in patients with abnormalities of coagulation [3]. This guideline classifies paravertebral block as ‘higher risk’ compared to more peripheral or superficial techniques, but provides no quantification of this risk, and does not reference any evidence documenting complications in patients with disorders of coagulation. Furthermore, we can find no case reports of spinal or epidural haematomas following ultrasound-guided paravertebral block performance. The practice of using curled catheters rather than straight in the paravertebral space further reduces the risk of inadvertent epidural placement. Our experience also reveals no associated haemodynamic instability following paravertebral blockade.

Their analysis revealed a statistically significant increase in spirometry values, but such improvement would be expected normally over time, with or without egional anaesthesia. Are the authors confident about ascribing causality between the block and the spirometry improvement, given the 24 hour gap between insertion and measurement? In our experience, spirometry improves very soon (within 30 minutes) after block insertion, and often improves further by the following day.

We suggest that paravertebral block overcomes the variability of analgesia observed in the authors' study, because it places local anaesthetic in close proximity to the target nerves, can be performed by a range of anaesthetist grades, is associated with minimal complications and side effects, and performance of which is contra-indicated in very few patients. Regardless of the block choice however, we agree with the authors that good analgesia (under the aegis of a comprehensive pain service) remains critical in the successful management of rib fractures.

M. James

R. Bentley

B. Goodman

Royal Victoria infirmary,

Newcastle upon Tyne, UK.

Email: michael.james3@nhs.net

No external funding and no conflicts of interest declared.

References

1. Adhikary SD, Liu WM, Fuller E, Cruz-Eng H, Chin KJ. The effect of erector spinae plane block on respiratory and analgesic outcomes in multiple rib fractures: a retrospective cohort study. Anaesthesia 2019; 74: 585-93. 
2. Womack J, Pearson JD, Walker IA, Stephens NM, Goodman BA. Safety, complications and clinical outcome after ultrasound-guided paravertebral catheter insertion for rib fracture analgesia: a single-centre retrospective observational study. Anaesthesia 2019; 74: 594-601.
3. Schnabel A, Recihl SU, Kranke P, Pogatzki-Zahn EM, Zahn PK. Efficacy and safety of paravertebral blocks in breast surgery: a meta-analysis of randomized controlled trials. British Journal of Anaesthesia 2010; 105: 842-52.
4. Association of Anaesthetists of Great Britain and Ireland, Obstetric Anaesthetists’ Association and Regional Anaesthesia UK. Regional anaesthesia and patients with abnormalities of coagulation. Anaesthesia 2013; 68: 966-72.

Working in a District General Hospital serving an elderly population, the recent Association of Anaesthetists guideline on peri-operative care of people with dementia is of particular relevance [1]. Any intervention that can minimise changes in cognition peri-operatively is of interest to anaesthetists. As a department motivated to reduce the environmental impact of anaesthesia, I was pleased to read that intravenous anaesthesia may be of potential benefit compared to inhalational agents. However, the Working Group also stated that ‘desflurane is preferable to sevoflurane and isoflurane’, but I was unable to find the evidence in the referenced articles by Fodale et al. and Eckenhoff et al. that supports this statement [2, 3]. Given that desflurane has a considerably higher global warming potential than sevoflurane or isoflurane [4], my department has sought to reduce the use of desflurane, limiting it to cases with sound clinical justification. Before allowing desflurane to become the volatile agent of choice for patients at risk of cognitive decline, our department would like to evaluate the evidence, and weigh this against the environmental cost. Would the authors be able to point us to the evidence for this statement, so that we can make an iinformed decision for both patient and planet?

S. Freeman

St. Richard's Hospital,

Chichester, UK.

Email: sfreeman@doctors.org.uk

No external funding and no conflicts of interest declared.

References

1. Association of Anaesthetists. Guidelines for the peri‐operative care of people with dementia. 2019. Anaesthesia 2019; 74: 357-72.

2. Fodale F, Quattrone D, Trecroci C, Caminiti V, Santamaria LB. Alzheimer's disease and anaesthesia: implications for the central cholinergic system. British Journal of Anaesthesia 2006; 97: 445–52.

3. Eckenhoff RG, Johansson JS, Wei H, et al. Inhaled anesthetic enhancement of amyloid‐beta oligomerization and cytotoxicity. Anesthesiology 2004; 101: 703–9.

4. Campbell M, Pierce T. Atmospheric science, anaesthesia, and the environment. Continuing Education in Anaesthesia Critical Care & Pain 2015; 15: 173-9.

I commend Adhikary et al. [1], Womack et al. [2] and El-Boghdadly and Wiles [3] for increasing the collection and interpretation of further evidence supporting the use of novel chest wall blocks for analgesia after rib fracture.

El-Boghdadly and Wiles assert “thoracic epidural analgesia should no longer be considered a first-line regional anaesthetic technique in these patients,” but also that this is the only analgesic modality with demonstrable effects on pain, pulmonary complications and mortality.

Given that the range of chest wall blocks detailed require varying degrees of specialist skills which may not be available in all centres, at all times, particularly out-of-hours, do El-Boghdadly and Wiles accept that thoracic epidural analgesia (TEA) should remain a skill taught to and practised by all anaesthetists? I am concerned that any recommendations abandoning TEA may lead to some anaesthetists avoiding analgesia administration rather than attempt a unilateral technique with which they are not familiar, worsening outcomes for the patient.

T. Heinink

Frimley Park Hospital,

Frimley, UK.

Email: tomheinink@doctors.org.uk

No external funding and no competing interests declared.

References

We read with interest the recent editorial ‘Caring for the ageing mind’ [1] accompanying the Association’s new guidelines on the peri-operative care of people with dementia [2]. Currently, attention is focused on ‘bundles’ of care (such as that supported by the Hospital Elder Life Program (HELP) initiatives) [3], and influenced by clinicians’ reliance on pharmacological interventions which have been shown to be ineffective, and may even be harmful [4]. Scott and Evered also note that it is still uncertain as to which anaesthetic technique is better in people with cognitive impairment, accepting that it is desirable to provide anaesthesia while minimising the physiological, as well as the psychological, stress and allowing a rapid recovery of cognition [1].

In this regard, we would like to draw readers' attention to a recently published Cochrane systematic review comparing the effect of intravenous and inhalational maintenance of anaesthesia on postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery [5]. Seven randomised controlled trials (that included 869 participants) reported postoperative cognitive dysfunction as an outcome, finding that dysfunction was reduced with intravenous anaesthesia, the odds ratio (95%CI) being 0.52 (0.31-0.87).  Although the evidence was considered to be ‘low-certainty’ (anaesthetists could not be blinded to the type of anaesthetic the patients received), this does offer some support to intravenous maintenance of anaesthesia.  There was, however, no evidence of a difference in postoperative delirium (5 studies including 321 participants, ‘very low’ quality of evidence). 

Dr Muataz Amare. MBBCh, FRCA.

Dissemination Fellow, Cochrane Anaesthesia Review Group.

Speciality trainee in Anaesthesia, Northwest School of Anaesthesia.

Dramare85@gmail.com

@Dramare85 (Twitter)

Address:104 Eastbank Tower

277 Great Ancoats street 

M4 7FD Manchester

Dr Mike McEvoy. MBChB (Hons), FRCA, FFICM.

Dissemination Fellow, Cochrane Anaesthesia Review Group.

Speciality trainee in Anaesthesia, Northwest School of Anaesthesia.

mmcevoy@doctors.org.uk

Dr Andrew Smith 

Co-ordinating Editor Cochrane Anaesthesia Review Group.

Andrew.Smith@mbht.nhs.uk

References

1. Scott D, Evered L. Caring for the ageing mind. Anaesthesia. 2019; 74:271-273.
2. White S, Griffiths R, Baxter M, Beanland T, Cross J, Dhesi J, et al. Guidelines for the peri-operative care of people with dementia. Anaesthesia 2019; 74: 357-72.
3. Hshieh TT, Yang T, Gartaganis SL, et al. Hospital Elder Life Program: systematic review and meta-analysis of effectiveness. American Journal of Geriatric Psychiatry 2018; 26: 1015–33. 
4. Neufeld KJ, Yue J, Robinson TN, et al. Antipsychotic medication for prevention and treatment of delirium in hospitalized adults: a systematic review and meta-analysis. Journal of the American Geriatrics Society 2016; 64: 705–14. 
5. Miller D, Lewis SR, Pritchard MW, Schofield-Robinson OJ, Shelton CL, Alderson P, Smith AF. Intravenous versus inhalational maintenance of anaesthesia for postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery. Cochrane Database of Systematic Reviews 2018, Issue 8. Art. No.: CD012317. DOI: 10.1002/14651858.CD012317.pub2. 

No external funding and no competing interests declared.                                                                                                       

We read with interest Charlesworth and Glossop’s editorial on postoperative pulmonary complications [1], and the paper by Bagchi et al. which it discussed [2]. The Bagchi manuscript seemed to show that volume controlled ventilation led to fewer postoperative pulmonary complications than pressure controlled ventilation.  Charlesworth and Glossop suggest that it is not the mode of ventilation per se, but the higher tidal volumes generated by pressure controlled ventilation that may cause complications; they noted, however, that evidence to support this was lacking. Specifically, they comment that "Randomised controlled trials and systematic reviews are therefore unlikely to advance our understanding of the reasons for and strategies to prevent postoperative pulmonary complications in the immediate future."

Whilst observational studies have much to contribute to knowledge, we would like to draw readers’ attention to a relevant recently published Cochrane systematic review of randomised controlled trials [3].

This review [3] included 19 trials with 1548 participants undergoing anaesthesia for abdominal surgery, heart surgery, pulmonary thromboendarterectomy, spinal surgery and knee surgery.  They compared ‘high’ (over 10mls.kg^-1) and ‘low’ (under 10mls.kg^-1) tidal volumes and examined 7 outcomes.  The authors found moderate quality evidence that higher tidal volumes (in this case over 10ml.kg^-1) were significantly associated with postoperative pneumonia and the requirement for both postoperative invasive and non invasive ventilation.

The authors of the Cochrane review planned to perform a subgroup analysis comparing pressure and volume controlled ventilation, but there were insufficient data in the trials to do this.

Whilst we agree that it is hard to dis-entangle the contribution of each element of a complex intervention to harm (or indeed benefit), there is some evidence for some of the aspects within a bundle of care. 

M. McEvoy

M. Amare

Dissemination Fellows,Cochrane Anaesthesia Review Group

Specialist Trainees in Anaesthesia, North West Deanery, UK

No external funding and no competing interests declared.

References

1. Charlesworth M, Glossop AJ. Strategies for the prevention of postoperative pulmonary complications. Anaesthesia 2018; 73: 923-927. doi:10.1111/anae.14288
2. Bagchi A, Rudolph MI, Ng PY et al. The association of postoperative pulmonary complications in 109,360 patients with pressure‐controlled or volume‐controlled ventilation. Anaesthesia 2017; 72: 1334-1343.
3. Guay J, Ochroch EA, Kopp S. Intraoperative use of low volume ventilation to decrease postoperative mortality, mechanical ventilation, lengths of stay and lung injury in adults without acute lung injury. Cochrane Database of Systematic Reviews 2018;  7. Art. No.: CD011151. DOI: 10.1002/14651858.CD011151.pub3.

Cheng et al. found that dexmedetomidine reduced the rate of immediate postoperative delirium and the rates of postoperative cognitive dysfunction (POCD) after three and seven days, respectively, in elderly patients undergoing scheduled laparotomy [1].

Postoperative neurological disturbances with impaired cognitive performance include POCD, delirium, dementia, central anticholinergic syndrome, and akineic crisis [2]. The authors assessed POCD and delirium and excluded patients with dementia using mini-mental state examination scores (MMES). The exclusion criteria included MMES < 20; however, a cutoff point of 24 has been considered as an indicator of cognitive impairment and is associated with the diagnosis of dementia. Moreover, MMES should be corrected for educational attainment and age [3]. Some authors did not recommend the clinical use of MMSE in individuals with less than a grade eight education [4], however patients with no education were included in the study.

There are many factors affecting the incidence of POCD, particularly old age, surgical and anaesthetic time, and extent of surgery. Thus, I wonder whether the authors should have highlighted the age of patients and type of surgery as a study limitation. The authors assessed short-term transient cognitive decline after scheduled laparotomy, with a primary endpoint of cognition on the seventh postoperative day. The threshold of 7 days for postoperative assessment of POCD is generally accepted in order to avoid any confusion with postoperative delirium and to exclude the general effects of any anaesthetic agents administered [5].

The authors calculated that a study size of 334 participants (167 per group) would have 90% power to detect a significant difference in POCD between the study groups. This study size actually achieves 80% power, and for 90% power the study size would need to be 438 participants (219 per group).

Yasser  Ali Kamal

Minia University,

El-Minia, Egypt.

E-mail: yaser_ali_kamal@yahoo.com.

No external funding or competing interests declared.

References

1. Cheng XQ, Mei B, Zuo YM, et al. A multicentre randomised controlled trial of the effect of intra-operative dexmedetomidine on cognitive decline after surgery. Anaesthesia 2019; 74: 741-750.

2. Rundshagen I. Postoperative cognitive dysfunction. Dtsch Arztebl 2014; 111: 119-25.

3. Crum RM, Anthony JC, Bassett SS, Folstein MF. Population-based norms for the Mini-Mental Status Examination by age and educational level. JAMA1993; 269: 2386–91.

4. Tombaugh TN, McIntyre NJ. The mini-mental state examination: a comprehensive review. J Am Geriatr Soc 1992; 40: 922-35.

5. Newman S, Stygall J, Hirani S, Shaefi S, Maze M. Postoperative cognitive dysfunction after noncardiac surgery: a systematic review. Anesthesiology 2007; 106:572-90.

Response to McGee and Gardiner: FURTHER THOUGHTS ABOUT THE "TRANSATLANTIC DIVIDE" IN BRAIN DEATH DETERMINATION 

McGee and Gardiner have published an interesting article about the differences in legal challenges to the concept of brain death (BD) in the USA, Canada and the UK [1]. During the last few decades, three main brain-oriented formulations of death have been discussed: whole brain, brainstem death and higher brain standards [2-5]. Bernat claimed that “the formulation of whole-brain death provides the most congruent map for our correct understanding of the concept of death” [6]. Bernat and his colleagues’ view about the defence of the whole-brain formulation of death was cited by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioural Research as the conceptual basis of BD.[5,7,8,9]. The President's Commission recommended the adoption by all US states of the Uniform Determination of Death Act (UDDA) [10,11].

Pallis articulated the brainstem death view which dismissed the use of EEG or cerebral blood flow studies as confirmatory tests in BD diagnosis [12,13]. According to McGee and Gardiner [1], the legal position in the UK is relatively well settled, because the historic Royal Colleges’ Code of Practice provides the accepted medical standard for declaring death in the UK [14]. The recognised standard for defining death is “the irreversible loss of the capacity for consciousness, combined with irreversible loss of the capacity to breathe and therefore irreversible cessation of the integrative function of the brainstem”.12-14].

The conceptual and practical difference in BD determination between the USA and UK has been known as the "transatlantic divide" [15].

A critical component of this controversy is when intracranial pathology is localised to the posterior fossa. Both intracranial blood flow and EEG may persist when a primary brainstem catastrophe, that does not produce markedly raised intracranial pressure, is present. [16-19]

Varela et al. recently analysed three cases out of 161 that met inclusion criteria (1.9% of all brain deaths during this period), further adding another patient from a different hospital [18]. All four patients suffered from catastrophic posterior fossa injuries, and therefore fulfilled the UK BD clinical criteria, including the apnoea test. Those 4 patients showed preservation of supratentorial blood flow, which disappeared after a period of between 2 and 6 days, then allowing a diagnosis of BD, according to the whole brain criteria adopted in USA. These authors concluded that patients with primary posterior fossa catastrophic lesions who clinically seemed to be brain-dead according to USA BD criteria would typically evolve from retaining, to losing, supratentorial blood flow. Therefore, the authors asserted that if CBF assessment is used as an ancillary test, providing an additional criterion for the declaration of BD, those patients are not different from those who become BD due to supratentorial lesions.

Nonetheless, the challenge of the aforementioned cases focuses on determining when the patients were brain-dead according to US or UK BD criteria. According to UK guidelines, patients were brain-dead after the first clinical evaluation and after 6 days all four patients were brain-dead according to US guidelines[20-23].

Therefore, in primary brainstem or cerebellar lesions, under the whole-brain formulation, several BD guidelines have stipulated that ancillary electrical and/or blood flow tests are needed to confirm BD diagnosis [3,20,24-28].

I agree with the Bernat et al. [5,8,9] that irreversible cessation of functions of the whole brain is BD, and means death of the individual, because the “brain is responsible for the functioning of the organism as a whole”.

McGee and Gardiner also emphasize the case of Jahi McMath as a reason for BD diagnosis controversies [1], but this is other story [20-22]. I was able to study Jahi McMath using ancillary tests, 9 months after her initial diagnosis, although I did not have access to her initial clinical history [20-23]. Preservation of intracranial structures, both in the brainstem and cerebral hemispheres was documented by MRI, nine months after a cardiac arrest, in spite of vast brain injury. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a BD diagnosis in Jahi.

True EEG activity was found in this case over 2 μV of amplitude. Moreover, the power spectra analysis showed predominant activity within the delta-theta range. The EEG may persist in posterior fossa catastrophes that do not produce raised intracranial pressure. Jahi presented with a huge lesion at the pons, extending to the medulla. All heart rate variability (HRV) bands were preserved in this patient (BD has been characterised by the loss of all HRV components). This is a demonstration of autonomic activity conservation in the medulla, within vagal and other autonomic central nuclei. Another significant finding was the autonomic reactivity, assessed by HRV, to “Mother Talks” stimulation, demonstrating remaining function at different levels of the central autonomic nervous system. These results might explain the video findings reported by Shewmon, who observed Jahi’s movements which he interpreted as responses to commands.

Jahi McMath was not in a coma because, although she showed a sleep-like state of unrousable, unresponsiveness without evidence of awareness of self or environment, and her clinical examination showed a complete absence of brain-stem reflexes and no spontaneous drive to breath (apnoea). This patient was not in either an unresponsive wakefulness syndrome (UWS) or in a minimally conscious state (MCS) state. The reason for this is that she had not shown intermittent wakefulness manifested by the presence of sleep-wake cycles or variably preserved cranial nerve function. Moreover, UWS patients can usually breathe on their own, without the need for mechanical ventilation. The possibility of being in a MCS and/or MCS-emergent state is excluded, because these patients show, upon clinical examination, recovery of cognitive functions [20-22]. When I examined her ancillary tests, she was not brain-dead. Therefore, I claimed that this is a new state of disorder of consciousness not previously classified [22].

C. Machado

Havana, Cuba

Email: braind@infomed.sid.cu

No external funding and no competing interests declared.

References

1.       McGee A, Gardiner D Differences in the definition of brain death and their legal impact on intensive care practice. Anaesthesia 2019.

2.         Machado C Death on neurological grounds. Journal of Neurosurgical Science 1994; 38: 209-22.

3.         Machado C. Brain Death: A reappraisal., Spinger, 2007.

4.         Bernat JL, Brust JCM Strategies to improve uniformity in brain death determination. Neurology 2019; 92: 401-2.

5.         Bernat JL A Conceptual Justification for Brain Death. Hastings Cent Rep 2018; 48 Suppl 4: S19-S21.

6.         Bernat JL The biophilosophical basis of whole-brain death. Society for Philosophical Policy 2002; 19: 324-42.

7.         Bernat JL The whole-brain concept of death remains optimum public policy. Journal of Law and Medical Ethics 2006; 34: 35-43.

8.         Bernat JL A defense of the whole-brain concept of death. Hastings Cent Rep 1998; 28: 14-23.

9.         Bernat JL How much of the brain must die in brain death? Journal of Clinical ethics 1992; 3: 21-6; discussion 7-8.

10.       Guidelines for the determination of death. Report of the medical consultants on the diagnosis of death to the President’s Commission for the Study of  Ethical Problems in Medicine and Biomedical and Behavioral Research. Connecticut Medicine 1982; 46: 207-10.

11.       Determination of death (Uniform Determination of Death Act of 1981); natural death (Natural Death Act of 1981).LEXIS District of Columbia code, 1981.

12.       Pallis C Further thoughts on brainstem death. Anaesthesia and Intensive Care 1995; 23: 20-3.

13.       Pallis C Brainstem death: the evolution of a concept. Seminars in Thoracic and Cardiovascular Surgery 1990; 2: 135-52.

14.       Diagnosis of brain death. Statement issued by the honorarysecretary of the Conference of Medical Royal Colleges and theirFaculties in the United Kingdom on 11 October 1976. British Medical Journal 1976; 6045: 1187-8.

15.       Wijdicks EF The transatlantic divide over brain death determination and the debate. Brain 2012; 135: 1321-31.

16.       de Fatima Viana Vasco Aragao M, van der Linden V, Petribu NC, Valenca MM, Parizel PM, de Mello RJV Congenital Zika Syndrome: The Main Cause of Death and Correspondence Between Brain CT and Postmortem Histological Section Findings From the Same Individuals. Topics in Magnetic Resonance Imaging 2019; 28: 29-33.

17.       Manara A, Varelas P, Wijdicks EF Brain Death in Patients With "Isolated" Brainstem Lesions: A Case Against Controversy. Journal of Neurosurgical Anesthesiology 2018.

18.       Varelas PN, Brady P, Rehman M, et al. Primary Posterior Fossa Lesions and Preserved Supratentorial Cerebral Blood Flow: Implications for Brain Death Determination. Neurocritical Care 2017; 27: 407-14.

19.       Machado C Diagnosis of brain death. Neurology International 2010; 2: e2.

20.       Machado C, Estevez M Reader Response: Practice Current: When do you order ancillary tests to determine brain death? Neurology and Clinical Practice 2018; 8: 364.

21.       Machado C, Estevez M, DeFina PA, Leisman G Reader response: An interdisciplinary response to contemporary concerns about brain death determination. Neurology 2018; 91: 535.

22.       Machado C, Estevez M, DeFina PA, Leisman G Response to Lewis A: Reconciling the Case of Jahi Mcmath. Neurocritical Care 2018; 29: 521-2.

23.       Machado CDPEMLGRRPCFJHJCMAEMYMY A Reason for care in the clinical evaluation of function  on the spectrum of consciousness   Journal Functional Neurology, Rehabilitation and Ergonomics and Rehabilitation 2017; 4: 542-56.

24.       Walter U, Fernandez-Torre JL, Kirschstein T, Laureys S When is "brainstem death" brain death? The case for ancillary testing in primary infratentorial brain lesion. Clinical Neurophysiology 2018; 129: 2451-65.

25.       Machado C Historical evolution of the brain death concept: additional remarks. Journal of Critical Care 2014; 29: 867.

26.       Machado C, Korein J Irreversibility: cardiac death versus brain death. Revies in Neuroscience 2009; 20: 199-202.

27.       Machado C Multimodality evoked potentials and electroretinography in a test battery for an early diagnosis of brain death. Journal of Neurosurgical Science 1993; 37: 125-31.

28.       Sawicki M, Solek-Pastuszka J, Chamier-Cieminska K, Walecka A, Walecki J, Bohatyrewicz R Computed Tomography Perfusion is a Useful Adjunct to Computed Tomography Angiography in the Diagnosis of Brain Death. Clinical Neuroradiology 2019; 29: 101-8.

I thank Cheng et al for their interesting trial highlighting the issue of postoperative cognitive decline and recognising that there may be agents at our disposal that can reduce the impact of general anaesthesia.  This is an important issue for anaesthetists around the world who are providing anaesthesia to an ageing population with increasingly complex comorbidities.

I was impressed to read that ten centres were involved in this trial and that they all delivered the same style of anaesthesia.  Is dexmedetomidine regularly used as an intra-operative agent throughout China?  I was left wondering what the function of a pre-induction bolus of dexmedetomidine was, as induction also involved the use of sufentanil and propofol, which would seem adequate.  I question whether blinding of the anaesthetist was compromised with this pre-induction bolus, as a clinical response, including sedation, hypotension and bradycardia may have occurred with dexmedetomidine and no response after a bolus of saline [1]. 

Cheng et al. made a noble effort to match the dexmedetomidine and placebo groups, however there appeared to be too many variables that were beyond their control.  Little information was provided concerning intra-operative variables, including the grade of the anaesthetist, the use of invasive monitoring and the need for inotropes and vasopressors.  In addition, once the patients left hospital, the environmental influences on cognitive decline and general health are unknown.  Nutrition, quality of sleep and optimisation of comorbidities can all influence the course of cognitive dysfunction [2].  Perhaps the future will involve identifying those patients at high risk for postoperative cognitive decline and ensuring additional care is in place once they leave hospital, in order to try and improve their outcomes. 

A.Jalaly

Royal Free Hospital

London, UK.

No external funding and no competing interests declared. 

References:

1. Cheng X.-Q, Mei B., Zuo Y.-M. et al. A multicentre randomised controlled trial of the effect of intra-operative dexmedetomidine on cognitive decline after surgery.  Anaesthesia 2019; 74: 741-750.
2. Scott-Warren V.L. Dexmedetomidine: its use in intensive care medicine and anaesthesia.  BJA Education 2016; 16: 242-246.
3. Vizacaychipi M.P. Post-operative cognitive dysfuction: pre-operative risk assessment and peri-operative risk minimization: A pragmatic review of the literature 2016.  http://criticalcare.imedpub.cm/postoperaive-cognitive-dysfunction-preoperative-risk-assessment-and-perioperative-risk-minimization-a-pragmatic-review-of-the-lit.php?aid=8722 (accessed on 27/07/2019). 

The article by Sivia and Pandit [1] provides a fresh perspective on a relevant and important issue concerning all anaesthetists. However, the model begins at the point when the anaesthetist decides to pick up the correct syringe from a drug tray inside the operating theatre. In reality, errors may begin much earlier and the model could perhaps be broadened to include other scenarios as well;

1. Preparing the drug trolley – there may be errors whilst preparing drugs. For example, if we make a mistake in drawing up fentanyl and draw up mephenteramine in the syringe meant for fentanyl, drug administration error will occur even if at a later time the user administers the right dose of the ‘right’ drug at the right time. The model does not incorporate such mistakes at present.

2. Transferring the correct patient to the operating theatre and making sure that the patient has followed pre-operative orders. The model does not consider the possibility of a mistake here either.

We thus believe that including these aspects in the model will make it more comprehensive and realistic.

S.D. Bloria

P. Bloria

No external funding and no competing interests declared.

Reference

1. Sivia, D. S. and Pandit, J. J. (2019), Mathematical model of the risk of drug error during anaesthesia: the influence of drug choices, injection routes, operation duration and fatigue. Anaesthesia, 74: 992-1000. doi:10.1111/anae.14629

I am concerned that Yeow at al.'s study may herald the beginning of a raft of new devices developed for emergency front of neck access (eFONA), having also recently become aware of the ScalpelCric (VBM Medizintechnik GmBH, Sulz am Neckar, Germany) [1]. The Difficult Airway Society (DAS) has only recently rationalised the terminology, technique and equipment for Plan D/'can't intubate, can't oxygenate' (CICO) across the UK, enabling the elimination of the myriad of needle cricothyroidotomy devices on airway trollies and in anaesthetic rooms, in turn obviating the inherent issues of varying manufacturer, cost, size, design complexity, technique, learning and teaching strategy, availability, success rate etc. It seems rather counter-productive to be developing a range of eFONA devices that will replicate many of the same problems. 

We welcome the publication 'Guidelines for day-case surgery 2019' in your June 2019 journal and were encouraged to read recommendation five that states 'All anaesthetists should be familiar with...regional nerve blocks and neuraxial blockade, such as spinal anaesthesia' [1].

We strongly agree with the editorial comment in Anaesthesia News of the same month from Dr El-Bogdadly in which he states that 'One of the most important recommendations for clinicians is that regional and spinal anaesthesia should be considered to enable early discharge' [2].  However Dr El-Bogdadly then goes on to question whether all clinicians will be able to deliver this standard of care and how feasible day-case spinal is in all centres.  Perhaps this is simply realistic, but is it acceptable?

Whilst we agree that regional nerve block mwy be a specialist skill not all anaesthetists will necessarily possess, spinal anaesthesia, in contrast, is a core skill.  Spinal Prilocaine and 2-chloroprocaine have been licenced and available for a number of years in the UK and should be available in all day-cse units for use when spinal anaesthesia is indicated.  We would go further to suggest that spinal anaesthesia should be offered as a choice to all patients in the day-case unit, if indicated, as part of informed discussion over choice of anaesthesia.

It is interesting to note that the RCOA curriculum for CCT in Anaesthetics (2010), Annex B, Core Level Training (3/6 months-24 months) restricts its mention of spinal anaesthesia to the Obstetric and Regional sections.  No mention is made in the day-case section.  We would suggest that in future all trainees in anaesthesia should be trained specifically in the use of day-case spinal anaesthesia as a core competency.

R Erskine

W Rattenberry

S Ralph

University Hospitals of Derby and Burton NHS Foundation Trust

Email: Robbie.erskine@nhs.net

1.  CR Bailey et al. Guidelines for day-case surgery 2019.  Anaesthesia 2019; 74: 778-792.

2.  Anaesthesia News. Kariem El-Bogdadly. June 2019; Issue 383: 20.

We read with great interest the comprehensive and important systematic review by Roth et al [1] regarding the bedside predictors of difficult airways.

However, we missed from this article some data and comments about the importance of cervical spine mobility in predicting difficult airway management.  Although this predictor is included in the Wilson score [2] which was analysed by Roth et al [1], we believe it should be referred to as an independent predictor of difficult laryngoscopy.

In our clinical experience as anaesthesia practitioners (TE – 40 years, AD – 30 years), we encountered many cases of difficult airway management caused by cervical spine mobility limitation (CSML).

This is the case not only in patients with immobilized C-spine as it happens in C-spine injury [3], rheumatoid arthritis, ankylosing spondylitis and other pathological conditions affecting the C-spine, but also in older patients [4], often suffering from cervical spondylosis affecting C-spine flexibility.

Mashour et al [5], reviewed the electronic charts of 14,053 patients and identified that 8.1% of them had some cervical spine movement limitation. When compared to control patients, the incidence of difficult laryngoscopy and difficult intubation was more than twice higher in patients with CSML ((P<0.0001).

There was no difference in the airway management difficulty, whether the movement limitation was for flexion or for extension of the C-spine.

The authors concluded that difficult intubation should be anticipated in patients with CSML who are ≥48 years old.

In view of these, we believe that C-spine mobility may be an independent predictor of difficult airway management.

Tiberiu Ezri, MD

Senior anaesthetist

Corresponding author

Surgical Day Surgery Unit

Kaplan Medical Center

Derekh pasternak 1, Rehovot, Israel

tezri@bezeqint.net

Phone: +973-50-6296904

and

Alexander Dukhan, MD,

Senior anaesthetist, Director,

Surgical Day Surgery Unit

dukhan@bezeqint.net

Kaplan Medical Center, Rehovot, Israel

References

Roth D, Pace NL, Lee A, et al. Bedside tests for predicting difficult airways: an abridged Cochrane diagnostic test accuracy systematic review. Anaesthesia 2019;74:915–28.

2. Wilson ME, Spiegelhalter D, Robertson JA, Lesser P. Predicting difficult intubation.Br. J. Anaesth. 1988;61:211-6.

3. Suppan L, Tramèr MR, Niquille M, Grosgurin O, Marti C. Alternative intubation techniques vs. Macintosh laryngoscopy in patients with cervical spine immobilization: systematic review and meta-analysis of randomized controlled trials. Br. J. Anaesth 2016;116:27–36.  

4. Ezri T, Weisenberg M, Khazin V, et al. Difficult laryngoscopy: Incidence and predictors in patients undergoing coronary artery bypass surgery versus general surgery patients. Journal of Cardiothoracic and Vascular Anesthesia 2003;17;321-4.

5. Mashour GA, Stallmer ML, Kheterpal S, Shanks A. Predictors of difficult intubation in patients with cervical spine limitations. J Neurosurg Anesthesiol 2008;20:110–5.

This is a fascinating study,¹ which arguably provides some support to ANZCA's dual commitment to cannula and scalpel eFONA approaches in CICO situations. The NAP4 group and DAS have never precluded the cannula technique and it should certainly be considered in familiar hands, by clinicians trained and competent in the technique, most likely in centres where HFJV is regularly undertaken (and where the appropriate equipment is readily available). 

The authors addressed several limitations of their study, but there are a few additional discussion points worthy of mention:

The participants were directed to make their eFONA attempt between the tracheal rings and not at the cricothyroid membrane (as recommended in the DAS scalpel-bougie-tube technique).² The tracheal ring interspaces are narrowed in sheep (relative to humans) and this is likely to have contributed to the high false passage rate with the scalpel-bougie-tube technique, exacerbated by the greater mobility of the ovine larynx and absence of muscle relaxation - making fixation of tissues more difficult (neuromuscular blocking agents were not administered, which is recommended in the DAS algorithm);²

The ovine larynxes utilised may not be entirely representative of the CICO patient. The sheep necks were thin with superficial larynxes, which does not reflect the typically higher body mass index of the CICO patient. Further research with obese neck mannikins³ may be more informative than ovine or porcine surrogates, despite the loss in realism in terms of tissue mobility, tactile temperature and bleeding. The larynxes in this study were also anatomically "normal" (disease-free), and whilst there are multiple causes of CICO, NAP4 demonstrated that Head & Neck surgical patients are particularly high risk.⁴ The scalpel technique may convey potential advantages in such patients. Where laryngeal anatomy is significantly distorted (due to the primary pathology or post-surgery/radiotherapy), the cricothyroid membrane and larynx may be more difficult to locate with a cannula, whereas surgical incision (+/- blunt dissection) may assist in exposing the relevant anatomical structures, and increase the chance of success (observed from personal experience);

The study's primary end point was time to oxygen delivery. This does not address the potential issues of ongoing high pressure oxygenation/ventilation via a cannula device, such as barotrauma, or the inherent reliance upon specialist equipment for safe delivery (the authors themselves highlight the necessity for the Rapid-O2^® device). The scalpel-bougie-tube approach is not the eFONA panacea, but it does avoid the significant variability in the equipment, cost, and the risk associated with many high pressure delivery devices, instead utilising standardised equipment that is universally available;

By informing the participants that a CICO situation had already been declared and directing them to perform eFONA, there is artificial separation from the crucially important human factors inherent with CICO situations. The study eliminates the effect of strategy formulation and planning for failure, situational awareness, task fixation, willingness/reluctance to transition (down the algorithm), recognition and declaration of failure, decision-making, communication and teamwork under pressure, and many more. For the purposes of this study, consideration of the eFONA procedure in isolation is clearly necessitated. However, it is worth emphasising that these non-technical aspects are absolutely essential when teaching eFONA and training for CICO situations as they may well be more important than the actual eFONA technique that is chosen. 

This study will certainly contribute greatly to the ongoing international discussion on the optimum eFONA approach. Whilst valuable research work such as this continues to search for the eFONA catholicon, augmented by real patient data from resources such as the Airway App,⁵ institutions must agree collectively on the particular technique(s) they are advocating and then train their staff regularly with the equipment provided at that hospital. 

References 

1. Rees, K. A., O'Halloran, L. J., Wawryk, J. B., Gotmaker, R. , Cameron, E. K. and Woonton, H. D. (2019), Time to oxygenation for cannula‐ and scalpel‐based techniques for emergency front‐of‐neck access: a wet lab simulation using an ovine model. Anaesthesia, 74: 1153-1157

2. Frerk C, Mitchell VS, McNarry AF, et al.Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. British Journal of Anaesthesia 2015; 115: 827– 48.

3. Kelly FE, Cook TM. Front of neck airway: the importance of the correct (obese) models and (trained) participants in study design. Anesthesiology 2017; 126:986– 7.

4. Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. British Journal of Anaesthesia 2011; 106: 617– 31.

5. Duggan, L. V., Lockhart, S. L., Cook, T. M., O'Sullivan, E. P., Dare, T. and Baker, P. A. (2018), The Airway App: exploring the role of smartphone technology to capture emergency front‐of‐neck airway experiences internationally. Anaesthesia, 73: 703-710. 


No competing interests declared. 

Dr Patrick A. Ward

Consultant Anaesthetist

Chelsea & Westminster Hospital, London, UK

We would like to congratulate and commend the authors on a very thought-provoking and high-fidelity study on the delivery and assessment of emergency front of neck access (eFONA). However, we would appreciate further clarification regarding some of the study limitations.   

Firstly, the participant’s prior experience in eFONA techniques is not described. The majority of participants were recruited from the Monash Hospital network and we wonder if familiarity with a cannula technique may have contributed to an over-estimation of beneficial effect of the cannula technique compared to the other.

We understand you based your course on the CICO programme developed at the Royal Perth Hospital.In a previous study by Heard et al there was a reported success rate of 100% of achieving adequate jet ventilation using a scalpel bougie technique (SBT).¹ There was an associated 20% failure to pass a size 6.0 endotracheal tube (ETT) over the bougie, due to not making the tract large enough to facilitate passage of the ETT, with a successful mean time of 61 seconds to ventilation. In your study you recorded a 35% failure rate using a SBT with 53% of these due to incorrect placement of the bougie leading to false passages. If the attempt was successful it took a mean time of 90 seconds. We understand the Perth group removed the oral ETT before attempts at eFONA, whereas in your study we understand that it was left in, do you feel this may have contributed to the difference in both time taken and success rate?

In your methodology there was no specified tracheal space given to candidates, it just states that candidates were encouraged to perform eFONA on the 'high' superficial part of the trachea. There were two attempts at SBT technique that had to be abandoned due to catastrophic bleeding, could this be secondary to a lower approach, placing the scalpel in the vicinity of the thyroid gland and its associated vessels? Could this be a reflection of a difference in identifying landmarks between the models used and human anatomy?

As mentioned in the limitations section; a cognitive error may exist based on the methodology of the study. This comes about when in each case the needle cricothyroid puncture was performed first and subsequent operators may have been lured into performing the next procedure in the same place, due to a successful previous attempt, despite the trachea and skin being quite mobile in sheep and therefore the skin no longer overlying the trachea. The trachea of a sheep has a decreased distance between the tracheal rings, would this naturally lead to a higher rate of success with a technique that requires a smaller window to advance the tracheal component of the eFONA? Also we noticed that this was a scalpel tracheostomy, not a scalpel cricothyroidotomy; would reduced space between tracheal rings in sheep have made it more difficult to insert a bougie and favoured a needle technique, whilst also increasing the incidence of distortion of the trachea while railroading the ETT over the bougie?

In previous studies, including the Difficult Airway Society Guidelines (2015), a SBT technique is advocated as it (if successful) provides the safest technique to oxygen delivery and time to oxygen delivery is very important in this situation.² We were therefore intrigued that your study did not clearly define time to oxygen delivery? We assume that it was chest movement but this is not clear from the paper.

The most common cause cited for failure with SBT was para-tracheal placement of the bougie. We feel that this may be related to the mobility of the tracheal structures in sheep and the diameter of sheep trachea. The importance of the bougie entering the midline is paramount for successful SBT and it is unclear from the study whether a sheep trachea is directly comparable to a human trachea.

We noticed that in eight cases there was a second attempt at cannula insertion. Was it the same operators who then went on to have difficulty in SBT and if so was it because they struggled with eFONA or that the second cannula attempt had distorted the anatomy leading to difficult SBT? Also was there any difficulty with SBT in these cases where emphysema or bleeding had already been caused by the cannula technique?

Hamaekers & Henderson stated in 2011 that there was no best method for eFONA and recommended that all anaesthetists have more than one method for eFONA as different situations require different techniques.  Overall we feel that this was a very interesting study and one which helps us begin to appreciate the different techniques available to us for eFONA.

References:

1. Heard et al. The formulation and introduction of a ‘can’t intubate, can’t ventilate’ algorithm into clinical practice. Anaesthesia 2009; 64: 601–608

2. Frerk C., Mitchell V.S. & McNarry A.F.et al.(2015) Difficult airway society 2015 guidelines for management of unanticipated difficult intubation in adults. Br. J.Anaesth. 115, 827–848

3. Hamaekers AE, Henderson JJ. Equipment and strategies for emergency tracheal access in the adult patient. Anaesthesia 2011; 66 Suppl 2: 65–80

Dr Umair Ansari & Dr Tim Davies

Advanced Airway Fellows

University Hospitals Coventry & Warwickshire NHS Trust, Coventry, UK

We read with interest the recent article by Hade et al[i] in Anaesthesia and commend them for their work developing an insertion bundle and diagram for optimum Central Venous Catheter (CVC) tip position on chest radiograph.

Our hospital has been using the Scottish Intensive Care Society Audit Group CVC insertion and maintenance bundle[ii] for over 10 years and this has had a significant effect on reducing morbidity and complications arising from line insertion, but is silent on the matter of CVC tip position.  

We note that Hade et al did not specify whether the line was shortened or whether secondary fixation devices were used. CVC lines can be shortened by use of the secondary fixation device which is in the CVC pack; however manufacturers do not provide these separately to allow a CVC with tip positioned in the right atrium to be drawn back and secured in a sterile manner.  Given the recent focus on ‘getting it right first time’ by the UK Faculty of Intensive Care Medicine[iii], having to perform a second procedure to adjust line length is clearly not desirable.

As a result, our department has been developing an aide memoire matrix for our line insertion pack (see Figure 1). This provides guidance on the appropriate line length, dependent upon the patient’s height and the insertion site.

 An audit of 200 post line insertion chest radiographs demonstrated that whilst only 1/50 lines was ‘too long’, 1/3 were too short. From this, a matrix was developed using Peres’ formulae for line length[iv]: Right Internal Jugular: (Height/10)cm, Right Subclavian: ((Height/10) – 2)cm, Left Internal Jugular: ((Height/10) +4)cm. We then simplified these formulae into two height ranges around a cutoff of 165cm (5’4”) as presented in Figure 1.

Post-intervention audit of 69 CVC insertions, adherence to this matrix demonstrated increased likelihood of optimal line tip position[v]. These lines were all inserted to the hub, without use of the secondary fixation device.

 The department developed a similar diagram to that presented by Hade et al (Figure 2) which demonstrates the acceptable limits for a CVC tip on a chest radiograph. Our guidance uses a ‘final tip position window’ bordered of one rib width above right main bronchus and 2 vertebral bodies below the carina, in keeping with the guidance of peripheral inserted central catheter line tip position published by Johnston et al in 2013[vi].

The diagram presented by Hade et al also appears to suggest that the upper SVC is an acceptable location for the CVC tip, which had previously been advised against for Percutaneously Inserted Central catheters (PICC) tip position by Johnston et al due to a higher rate of thrombosis, a greater risk of vessel wall erosion and a greater risk of malfunction when the line tip is in the upper superior vena cava.  This is in keeping with AAGBI guidance[vii]. Of course PICC lines can be cut to length where as CVC’s cannot, thus initial selection of an appropriate length of CVC is key to ensuring optimal tip position.

We hope that the work undertaken separately by hospitals on opposite sides of the globe might encourage discussion of best practice and development of international evidence based guidelines.

D Wright

D Williams

Dumfries and Galloway Royal Infirmary

Dumfries, Scotland.

E-mail:  d.wright3@nhs.net

No external funding and no conflicts of interests declared.

I was interested to read the article “a new role for anaesthetists in environmentally-sustainable healthcare” [1] and congratulate the authors for bringing this important issue to a wider audience’s attention.

Under the heading ‘Changing practice’ they are right to highlight the issues of volatile agents, it is what we do, but another thing that anaesthetists do more than any other specialty is administer injectable medicines, and this never seems to be given the same priority in environmental discussions. A significant change to reduce the environmental impact here is to always use injectable medicines in prefilled syringes. At a stroke this eliminates a whole series of unnecessary paraphernalia; packaging, ampoules, drawing up needles and lorries delivering these, etc which all impact on the environment and hospital costs. Prefilled syringes could be added to Figure1 and removing unneeded items always trumps reusing and recycling.

Prefilled syringes also improve patient safety which itself is a, possibly hitherto unrecognised and unmentioned, massive contributor to reducing healthcare’s environmental impact. Getting it right first time shortens hospital stays and uses less of everything. Medication-related incidents are the most common type of preventable patient harm (25% of identified harm) [2]. Prefilled syringes have been shown to reduce infections [3], again meaningfully reducing environmental impact.

Of 10 billion units of injectable medicines sold annually over 30% are already delivered in ready to administer prefilled syringe form but only 4% of these are used in the acute setting. Embarrassingly, anaesthesia is not a leader in this “our field” of administering injectable medicines and is way behind other areas of medicine. Many operating theatres have been purchasing and using pre-filled syringes of saline and lidocaine in urinary catheterisation kits for over 20 years, but the same hospitals and their infection control units are still content for anaesthetists to hazardously draw up their own medicines into syringes and then inject them directly into patients veins when 6% of them may be contaminated [4].

Anaesthesia, Intensive Care, and Pain Medicine should all now be demanding that every possible injectable medicine be supplied in prefilled syringes as a matter of urgency, not least for the environment. In 2018 the Royal Pharmaceutical Society said that manipulation of medicines in clinical areas should be minimised and recommended using prefilled syringes wherever possible [5]. This should also be a new role for anaesthetists in environmentally-sustainable healthcare.

D.K. Whitaker

Manchester, UK

Email: whitaker2000@gmail.com

DKW is a Past President of the Association of Anaesthetists and Chair of the Patient Safety Committee of the European Board of Anaesthesiology. He has received lecture fees from Aguettant Ltd and Medtronic, all of which were donated to Lifebox. No other external funding or competing interests declared.

References

1. Shelton CL, McBain SC, Mortimer F, White SM. A new role for anaesthetists in environmentally‐sustainable healthcare.  Anaesthesia 2019; 74; 1091-4.

2. Panagioti M, Khan K, Keers R, et al. Preventable Patient Harm across Health Care Services: Review and Meta-analysis (Understanding Harmful Care) July 2017 https://www.gmc-uk.org/-/media/documents/preventable-patient-harm-across-health-care-services_pdf-73538295.pdf (accessed 02/09/2019).

3. Gargiulo DA, Mitchell SJ, Sheridan J, et al. Microbiological contamination of drugs during their administration for anesthesia in the Operating Room. Anesthesiology 2016; 124; 785-794.

4. Bertoglio S, Rezzo R, Merlo FD, et al. Pre-filled normal saline syringes to reduce totally implantable venous access device-associated bloodstream infection: a single institution pilot study. Journal of Hospital Infection 2013; 84; 85-8.

5. Royal Pharmaceutical Society. Professional guidance on the safe and secure handling of medicines Appendix C: Operating theatres – supplementary guidance. 2018  https://www.rpharms.com/recognition/setting-professional-standards/safe-and-secure-handling-of-medicines/professional-guidance-on-the-safe-and-secure-handling-of-medicines (accessed 02/09/2019).