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July - August 2023

This issue features articles reviewed by contributors from the Perth Children's Hospital
Measured gastric fluid volume in children

Pediatric Anesthesia

Submitted October 2023 by Dr Pallavi Kumar

Read by 160 Journal Watch subscribers


Study Type: Single-centre, prospective study in paediatric perioperative day care at a university-affiliated tertiary care centre.


- Aspiration of gastric fluid contents was performed in anaesthetised children aged 1-18 years undergoing elective gastroscopy.

- Recorded data included: patient fasting time, last meal content, last clear fluid content, aspirated gastric volume and pH, as well as patient characteristics.


- No significant correlation was observed between clear fluid fasting time and the child’s residual gastric fluid volume per kg body weight, nor between clear fluid fasting time and the pH of the residual gastric fluid.

Take Home Message/Commentary

1) This study does address a relevant and important question in clinical anaesthesia – given there has been a push to reduce the clear fluid fasting time from the standard 2 hours to one hour/zero hours.

2) There have been recent studies on similar questions, but there are no randomized controlled trials assessing the risk of pulmonary aspiration. Available observational studies are underpowered. As such it is difficult to exclude higher aspiration risk with shortened fasting time in a prospective manner due to prohibitive sample size required to identify change in outcome.

3) The strengths of this study are that it brings to light an important question in paediatric anaesthesia – should we shorten the clear fluid fasting time.

4) The limitations of this study are that it did not answer the question it asked, i.e., whether the clear fluid fasting time should be reduced to less than 2 hours. The shortest fasting time was 1 hour and 40 mins in this study.

5) This study is applicable to our practice and population – however it does not change practice given the fasting time of the patients were not of a short enough duration to determine whether less than two hours fasting time versus more than two hours fasting time was not adequately studied.

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Pediatric Anesthesia

Submitted September 2023 by Dr Liam O'Doherty

Read by 210 Journal Watch subscribers

This review article provides a practical guide to optimise perioperative blood management in children. It identifies 5 ‘Error Traps’ in blood management.
1. Failure to recognise and treat perioperative anaemia.
2. Failure to obtain informed consent regarding blood conservation strategies and optimal blood component use.
3. Failure to consider specific intraoperative blood conservation techniques in children.
4. Failure to recognise and treat life-threatening haemorrhage in children.
5. Failure to prevent unnecessary transfusion and recognise the risks of over-transfusion.

Take home messages/commentary:
These error traps can provide the following ‘take home’ points:
- Have a strategy to identify and treat pre-operative anaemia. This may be prevalent in up to 68% of Australian Aboriginal children.
- Gain informed consent regarding blood products whilst including the paediatric patient who is mature enough to engage in the consent process. Address family specific issues e.g. Jehovah’s Witness.
- Consider cell salvage if >10% blood loss is expected in patients >10kg.
- Acute normovolaemic haemodilution has theoretical benefits.
- Use tranexamic acid if moderate to severe bleeding is expected.
- Paediatric massive haemorrhage may often be overlooked due to clinical variability, therefore be vigilant to monitor for signs of massive haemorrhage. Use a paediatric specific massive haemorrhage protocol.
- Avoid unnecessary or over-transfusion by identifying triggers and targets for blood product replacement. Consider avoiding transfusion in stable patients with Hb >7g/dL. Post-transfusion aim to target an Hb of 7-9 g/dL with consideration of other clinical factors.

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Updated consensus guideline recommendations by the Neuroprotective Therapy Consensus Review (NTCR) group

British Journal of Anaesthesia

Submitted September 2023 by Dr Megan Wellbeloved

Read by 165 Journal Watch subscribers

This is an updated guideline on targeted temperature management in adult patients in the critical care setting with intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH) or acute ischaemic stroke (AIS). This was developed using the Delphi method consisting of 19 panel members (all experts in the management of ICH, SAH and AIS). A survey was developed using recommendations from previously published guideline in 2018. These were then reviewed in three rounds: online survey, face-to-face meeting and post meeting reviews. Recommendations were made based on a cut off level of agreement of 80% of the panel.

Take home messages/commentary:
Recommendations for TTM in adult patients with ICH, SAH and AIS:
• Temperature should be measured continuously or hourly (4 hourly if not ventilated with AIS)
• An automated feedback-controlled device is recommended to treat neurogenic fever
• Temperature should be controlled for as long as there is a risk of secondary brain injury (determined clinically, with neuroimaging and monitoring)
• Core temperature (bladder and oesophageal) measurement is recommended (Tympanic membrane in non-ventilated patients)
• Recommended target temperature is 36.0 °C – 37.5 °C
• Maximum temperature variation should be < +/- 0.5 °C per hour and < 1 °C per 24 hours
• Neurogenic fever can adversely affect outcomes and TTM should be started at 37.5 °C
• It is important to distinguish between neurogenic fever and other causes of fever, and TTM may mask worsening infection
• Shivering should also be managed in this patient group. A step wise approach should be used with various agents as well as controlled warming < 1 °C per 24 hours
• This guideline has been developed for a specific patient group: adults with ICH, SAH and AIS in the critical care environment. These recommendations may not be applicable to the paediatric population or adults outside critical care (where the recommendations may be difficult to achieve).
• Limitations include those of the Delphi method itself as well as potential bias of the panel from neuro critical care in high resource setting. These recommendations may not be appropriate in other settings.
• No consensus obtained for:
o Which first line agent should be used to manage shivering
o Which metric should be used to measure quality of TTM

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A meta-analysis of randomized controlled trials

Pediatric Anesthesia

Submitted September 2023 by Dr Matt Jenke

Read by 198 Journal Watch subscribers

This article is a meta-analysis of randomised control trials analysing the effect of preoperative intranasal dexmedetomidine on emergence agitation (EA) and emergence delirium (ED) in paediatric patients after general anaesthesia.

Primary Outcome: Proportion of patients experiencing emergence agitation or delirium.
Secondary Outcome: Emergence time and rate of post operative nausea and vomiting.

The meta-analysis followed the PRISMA and GRADE protocols. Inclusion criteria was for randomised control studies evaluating the effects of dexmedetomidine verses placebo or control on EA/ED in paediatric patients. Twenty studies were included in the final analysis with a total of 2103 paediatric patients. 984 patients were in the intranasal dexmedetomidine treatment groups.

The incidence of EA/ED was 13.6% in the dexmedetomidine group compared to 33.2% in the control group (OR 0.25, CI 0.18-0.43; p=0.0000). Emergence time was significantly increased in the dexmedetomidine group with a mean difference of 2.42 minutes (CI 0.37-4.46; p=0.021). Emergence time was shorter when compared to ketamine and midazolam subgroups. Dexmedetomidine significantly reduced the incidence of PONV (OR 0.39, CI 0.24-0.64; p=.0002).

Dexmedetomidine has emerged as a genuine option for preoperative anxiolysis and this analysis has highlighted the drug's favourable effects for a patient focused post-operative experience - with reduced ED/EA and PONV, and without a clinically significant increase in emergence time.

Controlling for heterogenicity in the analysis was difficult due to the small number of trials and their sample sizes. There were few studies that compared dexmedetomidine to other frequently used premedications and were only done so at doses of 1-2micrograms/kg. A major limitation of the study was that there is no clear definition or assessment protocol for what constitutes EA/ED. The development of an internationally standardised assessment tool for EA/ED in paediatric patients should ideally be developed prior to undertaking future studies. The study did not assess the alleviation of pre-operative agitation and distress with dexmedetomidine.

Maintenance inhalational anaesthesia was used in 17 out of 20 studies with only one study mandating the use of TIVA. Propofol based anaesthesia is associated with both the primary outcome of reduced EA/ED and secondary outcome of reduced PONV. Greater use of propofol maintenance anaesthesia in the included trials may have impacted strength of this analysis. From this analysis it is unclear if TIVA would diminish or enhance the postoperative effects of dexmedetomidine.

The antiemetic effects of dexmedetomidine are currently unknown but are suggested to be trifold. Hypothesised mechanisms include direct noradrenergic inhibition at the locus coeruleus, sympatholysis to reduce adrenaline-associated nausea and vomiting and reduced opioid consumption.

Take home messages/commentary:
• At a dose of 1-2micrograms/kg pre-operative intranasal dexmedetomidine reduces ED/EA and PONV.
• It is unclear how this effect is altered if TIVA anaesthetic is used.
• Further research is required to assess the effect of intranasal dexmedetomidine on ED/EA when combined with other premedications.

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Acta Anaesthesiologica Scandinavica

Submitted September 2023 by Dr Neil Hauser

Read by 186 Journal Watch subscribers

This single-center retrospective observational study investigated the utility of a PCR respiratory panel (PCR FilmArray Respiratory Panel 2.1, Biomeriuex) to determine whether surgery should proceed or be delayed in paediatric patients presenting pre-operatively with a fever. The authors argue that while it is well documented that children undergoing surgery with an active upper respiratory tract infection (URTI) are at risk of developing peri-operative respiratory adverse events (PRAE), not all pre-operative fevers are due to an active URTI.

As such patients admitted pre-operatively who had a temperature of greater than 38 degrees celsius (<1y/o) or >37.5 degrees (>1y/o) were subjected to a nasopharyngeal swab (NPS). The sample that was then put through the FilmArray panel testing for 22 different respiratory viruses. Patients who tested positive had their surgery deferred and were followed up to determine whether they developed symptoms consistent with an URTI. Patients who had a negative FilmArray panel were allowed to proceed to surgery and observed as to whether they developed any PRAE.

68 patients underwent a preoperative NPS in the study, with 1 excluded from the final analysis (total = 67). 28 tested positive for a viral infection on the FilmArray PCR test, with 25 included in the analysis (3 underwent surgery despite testing positive – reasons not given). Of those included in the analysis, 11/25 (44%) subsequently developed a viral illness on follow-up.

In the negative group, 39 patients had no viral infection detected on FilmArray, despite their pre-operative temperature (1 was excluded from analysis as the surgeons delayed the operation – reason not given). Of the included 38 negative patients, none developed any PRAE. Although there was a statistically significant difference between the groups in terms of the proportion of patients that developed symptoms (p <0.001) and there was a positive OR of 29.6, the confidence intervals for this result were very large indeed (3.80 – 1356.01).

Take home messages/commentary:
The authors suggest the utility of this study lies in the potential use of the FimArray to screen paediatric patients presenting with a fever pre-operatively. The test is relatively quick to perform, and results are available within 45mins. While the risk of the patient developing features of a viral infection following a positive screening test is ultimately 50/50 there is reassurance in proceeding with a negative test as none of these patients developed any PRAE despite their preoperative fever.

Limitations include its retrospective nature, small numbers at a single-center and the fact that patients testing positive may have had an infection in the proceeding 6-8 weeks with a PCR test remaining positive for some time following infection. This may mean that some patients will have their surgery unnecessarily postponed as they may in fact not go on to develop PRAE.

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A prospective single-centre qualitative analysis

Canadian Journal of Anaesthesia

Submitted September 2023 by Dr Patrick Cowie

Read by 163 Journal Watch subscribers

This article explores parental experiences following paediatric adenotonsillectomy. The authors recruited parents of children having adenotonsillectomy over a year-long period at Montreal’s Children Hospital, Canada. The authors investigated what problems parents faced, what strategies they used to care for their child and what support was provided. The information was collected in a postoperative diary in either English or French. Return to hospital rate and reasons for re-admission were also recorded.

There is a well-presented flowchart showing recruitment and outcome. The annual caseload of patients between the ages of 2 and 12 adenotonsillectomy was 563, patients with significant co-morbidities were excluded. Of these, 355 parents were approached and 324 consented, leading to a study population of 317 parents. 63 were uncontactable after discharge, and 145 of the remaining 254 parents actually made comments in their postoperative diary. This showed 46% of parents (n = 145) completed comments in their diary. This is a reasonably large sample size and retention rate for a qualitative study.

Significant postoperative pain was not surprisingly the main issue encountered by parents, occurring in just over half of the patients. Other major issues were sleep disruption and poor oral intake including refusal of medications. Very few parents commented on significant PONV. Interesting issues included the discomfort caused by oral medications, even in liquid form, which made administration challenging. To help their children, parents used a combination of pharmacological strategies (there was no standard analgesic regime) and non-pharmacological strategies, such as distraction, cold foods or liquids. The use of morphine to promote sleep was a noteworthy finding, especially given the potential for opioid sensitivity in children with sleep disordered breathing or unquantified OSA. Of those parents who made comments in their diaries, 12% required to return to hospital – more for dehydration/ poor oral intake than for post-tonsillectomy haemorrhages. Interestingly, this figure was less than the return to hospital rates for parents who did not complete their diaries. The authors felt that completion of the diary and support of using pain scales made have been advantageous for these families.

Take home messages/commentary:
This article continues to reinforce the significant burden on parents or carers following adenotonsillectomy. It suggests that having structured pain scores and support may reduce return to hospital rates. The article is generalisable, presenting a paediatric common operation and achieving a relatively large study size. Limitations include the qualitative nature of the study, which makes any finding dependent on parental opinion and the authors’ interpretation of these, and the lack of a standard post-tonsillectomy analgesic regime now present in many hospitals.

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British Journal of Anaesthesia Education

Submitted September 2023 by Dr Hamish Johnston

Read by 143 Journal Watch subscribers

There is growing interest for artificial intelligence (AI) in medicine to assist in repetitive tasks, diagnosis, prediction, drug discovery, personalised treatment, and decision support. This article provides an overview of the same and introduces the reader to methods of assessing validity and clinical applicability of AI systems. Current challenges and pitfalls when AI is integrated into medicine is then discussed.

Take home messages/commentary:
AI applications relevant to anaesthesia that are currently under development include risk prediction modelling, estimating surgical time, risk of surgery cancellation, ultrasound image acquisition and predicting intraoperative hypotension. Clinical implementation of AI systems is scarce.

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Hospital Cardiac Arrest

Pediatric Critical Care Medicine

Submitted September 2023 by Dr Andrew Chazan

Read by 140 Journal Watch subscribers

Study type - A retrospective multicenter international cohort study
Methods - Data gathered from 2015 to 2020 in more than 50 paediatric hospitals internationally, looking at any patients 18 years or less who suffered in hospital cardiac arrest (IHCA) and had one or more shock delivery. Exclusion was any rhythm strips that were indecipherable due to artifact. Rhythm strips recorded by the defibrillators were examined independently by a paediatric electrophysiologist and a paediatric cardiac intensivist and divided into three groups- appropriate shock, inappropriate shock and indeterminate.
Findings - in the 5 years examined and after exclusion of uninterpretable events there was 381 shocks from 158 specific events to review. The review of these events showed the following: appropriate shocks N=219 (57% of total), inappropriate shocks N=113 (30% of total), indeterminate shocks 49 (13% of total).

Take home messages/commentary:
- Does the study address a relevant question?
Yes. It is helpful for us to know if there is room for improvement in assessment and management of paediatric cardiac arrest, specifically the determination of whether a rhythm is shockable or not. Myocardial stunning and the conversion of a non-shockable rhythm into VF are potential complications of such an error.

- Is there any research on a similar question?
According to the study there is no such information on paediatric practice, there is however data on adult IHCA which has shown similar rates of inappropriate shock delivery.

- What are the strengths of the study?
Multicenter, international and a clinically relevant question.

- What are the limitations of the study?
Retrospective data gathering. Study relies on two clinicians to make a decision about appropriate vs inappropriate shocks which could introduce bias. Some data lost due to uninterpretable (artifact) rhythm strips (37 events excluded). No mention of clinician seniority in terms of the person deciding to shock or not shock the patients.

- Is the study applicable to our practice or population?
Yes. However, the majority of the data (88% of all shocks delivered) came from the ICU or emergency department. This environment may differ from a theatre environment, in terms of likely causes of arrest and number of senior clinicians likely to be present.

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