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December 2023

This issue features reviews from contributors at the Royal Children's Hospital and Monash Children's Hospital in Melbourne.

Pediatric Anesthesia

Submitted December 2023 by Dr Frank Hsiao

Read by 165 Journal Watch subscribers

Take home summary
- This single centre study of 200 paediatric patients undergoing adolescent scoliosis surgery found that an increased volume of intraoperative crystalloid intake is an associated factor with perioperative allogenic blood transfusion
- Further studies are required to investigate a causal relationship

Background:
- Significant number of patients undergoing scoliosis surgery still receive allogenic transfusion, despite introduction of measures such as recombinant erythropoietin (rEPO), antifibrinolytic therapy (AFT), and cell-saver
- Optimisation of fluid intraoperative fluid therapy has been shown to decrease perioperative complications in adults
- This study aimed to identify other potential risk factors for perioperative allogenic transfusion

Study overview:
200 paediatric patients in a single centre in France undergoing surgical correction of adolescent idiopathic scoliosis over a 2 year period (2018-2020)
Aimed to investigate the following factors and their association with allogenic transfusions
o body mass index
o preoperative haemoglobin concentration
o thoracoplasty
o preoperative halo-gravity
o volume of intraoperative crystalloid administration
o use of oesophageal Doppler (for goal-directed fluid therapy)
o and duration of surgery

Standardised perioperative management
- Preoperative rEPO and iron supplementation
- Intraoperative TXA, ketamine, dexmedetomidine
- Discretionary use of oesophageal doppler to guide fluid therapy (not mandated)
- Intraoperative dexmedetomidine
- Intraoperative cell saver
- Intrathecal morphine

Results:
- 12/200 (6%) patients required allogenic blood transfusion
- Out of the factors considered, normalised intraoperative fluid administration was the strongest associated factor with allogenic transfusion
- The authors postulate that this may be related to haemodilution in the setting of SIADH and fluid retention, although no causative relation can be made
- There was not a statistically significant difference in intraoperative cell saver blood transfusion to suggest a difference in intraoperative blood loss
- The authors advised caution in generalising the result in the context of a small, monocentric study

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A survey of practice in France

Pediatric Anesthesia

Submitted December 2023 by Dr Meghan Cooney

Read by 303 Journal Watch subscribers

Summary:
This study describes the practices and preferences of pediatric anaesthetists in France, when presented with a survey with an anaesthetic scenario of tracheobronchial foreign body aspiration.

Methods:
A survey sent via email in 2021. A clinical case of a 3 year old with a tracheobronchial foreign body was described. Questions were asked regarding anaesthetic technique, monitoring, as well as the experience of complications in such situations.

A total of 151 physicians responded to the survey.

Key findings:
Relatively few respondents had an algorithm for the management of tracheobronchial foreign bodies in their institution, and only a quarter of respondents who reported a specific algorithm for anaesthetic management in their institution.

Airway management was variable for rigid bronchoscopy, most reported that they aim to maintain spontaneous ventilation, while 48.3% stated using controlled ventilation through a rigid bronchoscope. Jet ventilation and the use of high flow nasal cannula were not commonly used.

The airway management for flexible bronchoscopy was more evenly distributed between the various options.

This article promotes the idea that “virtual endoscopy” utilising CT may have a role in excluding airway foreign bodies and thus avoiding negative bronchoscopies, however, it is not a perfect solution. The practicalities of CT in these cases are limiting, as these cases tend to be smaller children, who are unable to co-operate with the required breath holds.

The article rightly identifies that if general anaesthesia would be required for the CT, then it would be wise to proceed directly to bronchoscopy. Flexible bronchoscopy for removal of the foreign body was not available for the majority of respondents, but may offer less traumatic retrieval.

Complications that respondents had encountered were common, for example desaturation, broncho- or laryngospasm. Reassuringly, recovered cardiac arrest was rarely reported with no patient deaths described.

Discussion:
To be representative with a confidence interval of 95% and a risk of error of 5%, they required 189 respondents, however they only obtained 151 responses.

The information on which respondents would undergo this case in an asymptomatic patient at 1am was confusingly reported but seemed high. Most respondents opted to wait until the child is considered fasted if otherwise stable.

Take Home Message:
There is a lack of planning protocols and institutional guidelines in approaching the diagnosis, and anaesthetic management of these cases.

There is diversity in anaesthetic technique, but there seemed to be a dominating aim to maintain spontaneous ventilation using inhalational, intravenous and local anaesthesia.

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A quality improvement report

Pediatric Anesthesia

Submitted December 2023 by Dr Tracy Jackson

Read by 186 Journal Watch subscribers

The environmental impact of anaesthetic gases are of increasing concern. In Australia and New Zealand, children are traditionally induced by gas induction with high flow nitrous/oxygen and sevoflurane. High fresh gas flows (FGFs) are traditionally used to speed up induction, although once the circuit is primed FGFs above minute ventilation do not change speed of induction. The Society of Paediatric Anesthesia recommends 0.15/min/kg as the minimum safe and effective FGF during induction i.e . 3L/min for a 20kg child. Many anaesthetists routinely run 6-10L/min regardless of the child’s weight.

The authors instituted 4 interventions with the aim to decrease nitrous oxide usage from 80% to 20% and reduce maximum FGF from a baseline of 0.53L/min/kg. Interventions included – a lecture on environmental impact of anaesthetia from a visiting professor, survey of nitrous oxide usage with repeat education, visual reminders of recommended minimum FGF rates, FGF rates as screen saver on anaesthesia work stations.

The authors analysed 33 285 anaesthesia records over a 20 month period. Emergency surgery, planned IV induction and ASA 3 patients were excluded. A subset of patients undergoing insertion myringotomy tubes were analysed for speed and quality of induction and mask acceptance.

Results: Nitrous usage dropped from 75% to 25% following intervention 1 &2 with a slow decrease to 15% by the end of the study. Maximum FGF decreased by 30% over the study with the greatest change in smaller patients. Induction times increased initially but returned to baseline after a few months. Induction behaviour scores and mask acceptance was unchanged.

Conclusion
Education if followed up with visual reminders can be a powerful tool to change behaviour. The authors note that the visiting speaker was invited due to a general interest in the department to improve environmental practices, therefore there primed for change. The avoidance of nitrous and “low flow” gas inductions did not change the speed and quality of the induction. This has been supported in other studies (Singh, 2019).

Criticism
All patients over 12 months were offered a midazolam premed. There was no data as to the number which received a premed. This may influence the quality of induction and mask acceptance and not reflect standard practice in Australia and New Zealand.

As a throwaway line in the discussion the authors note the issues with piped nitrous. Multiple studies both in Australia/Nz and worldwide have found 80-90% of nitrous is lost to leaks before even reaching a patient. Therefore decreasing nitrous usage without decommissioning pipeline supply is not likely to make a huge difference. That said, reducing nitrous usage from standard to occasional practice can allow for easy the change to cylinder supply.

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Pediatric Anesthesia

Submitted December 2023 by Dr Shravya Karna

Read by 172 Journal Watch subscribers

Summary:
Despite one-lung ventilation providing optimised surgical conditions, positioning an extraluminal Arndt endobronchial blocker (AEBB) remains challenging particularly in children aged less than 6 years. Dislodgement and replacement is near impossible during surgery. The authors describe a novel technique described by Enk that allows for quick and effective placement and replacement using an angled wire.

Technique:
1. The nylon loop is removed from a 5-French AEBB. The port is flushed with saline to decrease friction
2. The AEBB is passed through the vocal cords under direct laryngosopy followed by a half size smaller ETT next to it
3. Positioning of the AEBB is finalised after surgical positioning
4. An angled, half-J tip Terumo Glidewire (0.018 * 80cm) is placed into the AEBB such that the angled end protrudes past the distal end of the AEBB
5. A fibreoptic bronchoscope is passed through the ETT to visualise the wire above the carina
6. Roll the proximal end of the wire between the fingers, this will direct the distal angled tip
7. The AEBB is passed over the wire under and the balloon inflated under FOB visualization.
8. After securement, the wire can be removed to allow for lung deflation and suctioning.

The authors have successfully used this technique in over 50 infants and toddlers, including infants with bronchopulmonary sequestration, vascular ring and congenital pulmonary airway malformation.

Key Messages:
The Enk technique has been more successful than traditional methods for placement and replacement of AEBB, allowing for faster and safer OLV.

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Pediatric Anesthesia

Submitted December 2023 by Dr Eamonn Upperton

Read by 165 Journal Watch subscribers

Inspired by the SAFETOTS ‘10Ns’ of quality in paediatric anaesthesia, this paper sets out to measure how often physiological variables stray outside the target range during and after neonatal surgery.

The authors retrospectively analysed parameters from 53 gastroschisis repairs, reporting whether each was kept within a pre-defined range for a specified percentage of the case. The parameters examined were:
• Mean arterial pressure
• Heart rate
• Temperature
• End-tidal CO2
• Oximetry
• Blood glucose
• Serum sodium

The primary outcome of the study was to determine how many of these parameters were measured in each case. These were well monitored, with a median 6 of 7 variables measured (range 4-7).

The secondary outcomes analysed the frequency with which these parameters were kept within a retrospectively applied target range. Of these, only oxygen saturation and heart rate were kept within range in more than 80% of cases.

The findings in this paper demonstrate some of the challenges inherent to developing indicators of quality in anaesthesia; namely, that measured parameters are often a surrogate for the actual variable of interest. Here, 72% of the neonates undergoing anaesthesia experienced blood pressure measurements below the target for greater than 25% of the duration of the case; whether this translates to low end-organ perfusion is not clear.

As a less frequently measured variable, the inclusion of “normal serum sodium” in SAFETOTS is in part a recognition of the risks posed by “4% and a fifth” hypotonic crystalloid solutions. The authors of this paper sensibly recommend that using a balanced crystalloid solution in routine surgery may preclude the need for sodium monitoring.

The anaesthetic technique described here has some notable differences to local practice, which may have influenced the physiological variables to some degree. For example, in most cases (86%) anaesthesia was induced in NICU by the neonatologist before transfer to the operating theatre. Even with these variations in technique, the difficulty we face in meeting parameter targets for these patients is evidently universal.

This paper highlights the challenges of translating imperfect physiological measurements to markers of quality. Despite the difficulty of consistently achieving these physiological aims, it may well be that the pursuit of target parameters is more important than the absolute numbers themselves.

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Invasive blood pressure in children undergoing cardiac catheterization

Pediatric Anesthesia

Submitted December 2023 by Dr Su May Koh

Read by 179 Journal Watch subscribers

This was a multicentre prospective observational study of 254 children aged under 16 undergoing cardiac catheterisation where paired non-invasive and invasive blood pressure measurements were compared. Three paediatric hospitals were involved and 683 paired blood pressure values were collected. The overall bias (SD) for mean arterial pressure was 7.2 (11.4) mmHg, however during periods of hypotension the bias (SD) was even greater at 15 (11.0) mmHg. The authors also interestingly commented that NIBP (non-invasive blood pressure) generally overestimates MAP (mean arterial pressure) in infants under a year of age and underestimates MAP in older children.

The study authors concluded from the study that non-invasive blood pressure measurements are unreliable in anaesthetised children during cardiac catheterisation and that invasive blood pressure should be instituted for high-risk cases.

This is an important study as accuracy of blood pressure monitoring is vital during anaesthesia especially during high-risk anaesthesia or periods of hypotension. Invasive arterial monitoring remains the gold standard but is not without its risks, so it is important for anaesthetists to be aware of the limitations of NIBP measurements. The authors also highlight the limited studies comparing NIBP and invasive BP monitoring in children under anaesthesia, hence the importance of their study.

The study included patients for cardiac catheterisation where invasive BP monitoring was planned already and this was paired with NIBP (Phillips Intellivue monitors). It is important to note that NIBP algorithms do vary between different monitors and hence this study may not be as generalisable as one might think. The study population of patients with congenital cardiac disease also makes this study less generalisable to the general paediatric population. It is important to bear in mind that often during cardiac catheterisation the patient arms are raised above the head so this may also affect NIBP measurements and potentially present a bias as well.

Take home message:
This study does highlight that anaesthetists need to be aware of the limitations of NIBP measurements particularly in high-risk patients and during periods of hypotension.

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Pediatric Anesthesia

Submitted December 2023 by Dr Su May Koh

Read by 55 Journal Watch subscribers

Illicit substance use is increasing in the teenage and adolescent population and relying on parental history alone is unlikely to be reliable. Illicit substance use and abuse not only has consequences in terms of acute toxicity but can also impact on perioperative care and morbidity. This study compared anonymous answers to a preoperative survey completed by the patient to history obtained from the parent or guardian.

This single site American study involved 250 patients aged 12-21 with a median age of 16. Not surprisingly the study showed higher reporting of substance use or abuse from the patient survey compared to the routine parental history. Alcohol use rates were highest with 27.6% of patients reporting alcohol use compared to 2% of parents reporting this. Alarmingly 2.9% reported using alcohol within 24 hours of coming in for their elective surgery and 6 patients reported marijuana use within 24 hours prior to surgery. 16% of adolescent patients reported vaping compared to only 4.4% of parents. Marijuana use was reported in 20.8% of patients but by only 4.4% of parents. With the increase in vaping, tobacco use rates were lowest with only 4.8% of patients reporting this and 2% of parents.

This study clearly highlights the discrepancies between parental knowledge and reporting of illicit substance use by their teenage or adolescent children. This is not surprising but is an important sign that the current practice of preoperative history taking from the parents is unlikely to be accurate. This is most likely also the current practice of many paediatric institutions.

The authors comment that identification of illicit substance use is not only important to prevent perioperative complications but also may allow for interventions to change behaviour and substance abuse in the longer term. This study sought to identify a more effective way of accurately identifying substance use in teenagers and adolescents using an iPad survey (without parental oversight) preoperatively on the day of surgery. The authors report that this was possible even within the busy workflow of the preoperative area in a tertiary paediatric hospital.

Take home message:
Illicit substance use is a common and increasing problem in teenage and adolescent patients presenting for surgery and current preoperative assessments which rely on parental history are likely to be inaccurate as shown by this study. Institutions need to find new ways of ascertaining more accurate substance use information from these patients in order to ensure more comprehensive perioperative care.

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Anaesthesia

Submitted December 2023 by Dr David Rawson

Read by 39 Journal Watch subscribers

This study examined the effectiveness and safety of a hybrid technique – videolaryngoscope (VL) with flexible bronchoscope (FB) – in paediatric patients with difficult tracheal intubation.

Methods:
- A retrospective analysis of data from the International Paediatric Difficult Intubation Registry from 2017-2021
- The hybrid technique was compared to FB alone

Results:
After propensity score matching, groups were well balanced:
- Hybrid group: 140 patients for 182 intubation attempts

- FB group: 560 patients for 800 intubation attempts

The primary outcome was first-attempt successful intubation rate:
- There was NO significant difference between hybrid and FB groups
- This was the case whether used as a primary technique or as a rescue technique

Secondary outcomes:
- Eventual success rate - NO significant difference between the groups
- Complication rate - NO significant difference (and severe complications were very rare)
- Technical difficulty - higher in the Hybrid group (36%) than the FB group (28%), p = 0.04

The most common difficulty in the hybrid group was ‘directing the tracheal tube despite an adequate view’

The use of standard or hyperangulated laryngoscope blade made NO difference to first attempt or eventual success rates in the hybrid group

Crossover encounters
- A hybrid technique was able to rescue a failed FB technique in 21/24 cases
- An FB technique was able to rescue a failed hybrid technique in 2/7 cases

Limitations:
- Observational study, so no randomisation
- Groups matched for age, weight, ASA, sex. Possible other confounders exist.
- No consideration of the differences of experience of the intubating anaesthetist

Thoughts:
- While not demonstrated here as a ‘game-changer’, the Hybrid technique provides a safe and efficacious alternative to other ‘hi-tech’ advanced airway techniques. It is, I think, certainly worth considering as part of a paediatric difficult airway plan.
- Technical difficulties are significant. The pre-matched data shows that Hybrid success rates improve with increasing weight and age (whereas FB success rates no not). This might suggest that one of the big challenges is training to expertly manipulate 2 airway devices (by 2 operators and with 2 screens) in the confined physical space of an infant airway.
- It is used more commonly than FB as a rescue device, and does seem to have good results in that context.

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Journal Watch is a community of SPANZA members who work to identify and review articles of interest in the paediatric anaesthesia literature.


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