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May - June 2023

This issue features reviews from Christchurch and Starship Hospitals in New Zealand

Pediatric Anesthesia

Submitted August 2023 by Dr K C Law

Read by 181 Journal Watch subscribers

Summary
This is a retrospective single-center cohort study looking at using ultrasound to place longer length peripheral intravenous cannulae to prolong its indwelling life-span and use, increase placement success rate, and decrease need for multiple further cannulation events.

The 187 study sample came from Pediatric Critical Care Department, Pediatric Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA, which is a tertiary 25-bed mixed cardiac and pediatric intensive care unit. 88 patients received standard cannulae which were 1.9cm 24G, 2.5cm 22G, and 3.2cm 20G, and these were placed ‘traditionally’ using landmarks, vein palpation, and use of vein illuminator device. The other 99 patients were identified by ICU nurses as difficult cannulation at their discretion, often after two failed attempts using traditional cannulation approach; these patients had a longer length cannula placed using ultrasound (US) guidance done by vascular access team or intensivists with cannulae used being one of 3.2cm 24G, 4.4cm 22G, or 4.4cm 20G.

Findings
The majority of traditional approach placement sites were on the hand (31 cases), forearm (23 cases) and foot (20 cases), while the majority of the US-guided placements were on the forearm (55 cases) and upper arm (36 cases). Interestingly, the median age for the traditional group was 10 months, and for US group were 58 months, with 33 months as median age for the overall sample.

The median catheter in-dwelling time for the longer cannulae was 219 hours versus 108 hours for the traditional cannulae. Patients in the traditional group were also more likely to have their cannulae “fail”, needing further cannulation when adjusted to length of hospital stay. However, there are cannulae in both groups that survived over 300 hours. Reasons for cannulae removal included therapy completion, infiltration, impaired catheter integrity, site tenderness, catheter leak, accidental removal, occlusion, and bleeding at insertion site. Complication rates and need for central line placements were similar between the two groups.

Take Home Message / Commentary
This is an interesting study that looked at intravenous cannulation, which is inarguably one of the commonest invasive procedure performed in hospital. The study is laudable for raising questions on technique, possible improvement indicators, and inquiring on the patient experience dimension.

The stated study limitations include a lack of measurable criteria used to identify difficult venous access, lack of documentation on number of attempts before successful cannulation, potential bias from the (perhaps surprisingly) greater number of older-aged children in the US group, the absence of causal-relationship analysis between the type of medication/infusion with cannulae longevity, and potential operator bias from the separate vascular access team being wholly responsible for traditional cannulation and the US group mainly done by intensivists.

In addition to these stated study limitations, it would be useful to know if other factors influence cannula longevity such as make and design of cannulae used; the length or portion of cannulae inside the vessel; the size of vessel relative to diameter of cannulae used and its association, if any, with thrombosis; influence of type of cannulae care such as interrupted flushing technique with saline after cannula access; and patient/carer satisfaction. These data would help cannulation decision with regards to factors like type of cannula, site, approach, and aftercare needed.

Overall, this is a useful paediatric study lending weight to the argument for incorporating routine use of ultrasound for vascular access. The routine use of midline cannulae to increase cannulae longevity is less clear-cut due to other potential confounders not being accounted for in this study, but nevertheless, is useful as reflection to look for methods to further improve peripheral venous cannulation.

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A randomized crossover mannequin study

Canadian Journal of Anaesthesia

Submitted August 2023 by Dr Caroline Mann

Read by 213 Journal Watch subscribers

This is a single centre randomized crossover trial comparing applied oropharyngeal forces of tracheal intubation of direct laryngoscopy versus video laryngoscopy in a neonatal manikin.

Manikin intubation was demonstrated. Oropharyngeal forces were then compared during intubation using a straight blade direct laryngoscope (Miller 1), straight blade video laryngoscope (Glidescope Miller 1) and hyperangulated videolaryngoscope (Glidescope LoPro S1). Pressure sensors were attached to the laryngoscope blades. The manikin was a Laerdal Newborn Anne. A 3mm ETT and stylet were used.

Participants were 30 neonatal/anaesthetic/paediatric specialists and trainees.

Primary objective: comparison of maximum peak oropharyngeal force

Secondary objectives included comparison of average peak force, time to intubate and subjective workload (using the NASA Task Load Index).

Key Findings

• Less force was required for videolaryngoscopic intubation with straight or hyperangulated laryngoscope blades compared with direct laryngoscopy

• When comparing direct laryngoscopy vs hyperangulated videolaryngoscopy, median differences between maximum peak forces were 5.3N (99%CI 3.9-7.2). Median difference between average peak was 7.3N (99% CI 4.1-8.8N)

• When comparing direct laryngoscopy vs straight blade videolaryngoscopy there was no detectable median difference in peak pressures

• No differences were found for time to intubation or subjective workload

Discussion

This study addresses the issue of force required for neonatal intubation, which is clinically relevant to this vulnerable population. This is especially important for premature neonates at higher risk of intraventricular haemorrhage and oropharyngeal trauma. Recent research in this area has mainly focused on adult studies, which show similar results of reduced force for intubation using videolaryngoscopy vs direct laryngoscopy.

This is a reasonably well designed study using appropriate equipment and a simple crossover design.

The main study limitation acknowledged by the authors was that manikins were used. The authors recommend further clinical studies before drawing significant conclusions.

Intubation is very different in actual neonates. Techniques to optimise neonatal intubation including patient positioning and laryngeal manipulation to bring the vocal cords into view, which are often used in vivo as neonatal tissues are soft and malleable, therefore laryngoscopic forces used may be much lower.

Intubation experience of the participants was wide ranging, from senior neonatal anaesthetists to junior trainees, which may have led to wide ranging results, but also reflect the intubators in clinical practice.

Laryngoscopic technique may have varied, despite demonstration. Successful neonatal intubation with minimal force is usually dependent upon the operator’s technical skill, including placing the laryngoscope blade tip in the correct area, the ability to swiftly adjust tip position and laryngeal manipulation to bring the cords into view without repeat laryngoscopy.

In vivo other outcome measures indicating pressure and stimulation such as heart rate and arterial pressure changes may also be monitored. Other factors potentially causing trauma clinically include oropharyngeal trauma from intubators inadvertently blindly advancing the stylet/endotracheal tube during videolaryngoscopy, which may be a relatively common issue in inexperienced videolaryngoscope users.

Despite these limitations, the findings fit anecdotally with that of experienced neonatal intubators. That is that less force is required during videolaryngoscopy of neonates especially when using hyperangulated blades. This is relevant to all neonatal intubators.

Take Home Message
Less force may be required for neonatal intubation using videolaryngoscopy vs direct laryngoscopy

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Long-Acting, Short Acting, or Not Acting

Anesthesia Analgesia

Submitted August 2023 by Dr J Houghton

Read by 188 Journal Watch subscribers

Recent studies have shown a reduction in perioperative respiratory adverse events (PRAE) especially the major PRAEs bronchospasm and laryngospasm with short acting inhaled beta agonists.

This editorial refers to an article that describes the application of a transdermal patch - tulobuterol - as a means of reducing PRAE.

Given this the benefit of a transdermal patch that is not universally available and requires placement 8-10 hours pre procedure is not clear when compared to readily available nebulised beta agonists such as salbutamol.

There are issues with the studies definition of PRAEs especially as desaturation and cough are relatively inconsequential in the setting of airway surgery as opposed to laryngospasm and bronchospasm.
The true incidence of laryngospasm and bronchospasm are uncertain but best estimates are 1.7-9.6% for laryngospasm and 1.7% for bronchospasm.Therefore, the study sample size is insufficient to determine a difference in laryngospasm/bronchospasm in the treatment group.

Furthermore, children with known reactive airways disease and recent respiratory tract infection were excluded. Reactive airways are common in children undergoing tonsillectomy and these children are the group at highest risk of PRAEs. By excluding this group of children, the studies applicability is further reduced.

When aiming to reduce PRAEs we should target those at greatest risk ie those with reactive airways or a current or recent RTI. This can be achieved readily with inhaled beta-agonists in a more available and easier to perform manner.

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A Randomized Controlled Trial

Anesthesia Analgesia

Submitted August 2023 by Dr J Houghton

Read by 159 Journal Watch subscribers

Hypothesis:
Inhaled B-2 agonists have proven benefits in reducing the incidence of paediatric perioperative respiratory adverse events (PRAE). Therefore, transdermal tulobuterol (peak effect 9-12 hours post application with 24-hour efficacy) should decrease the incidence of perioperative adverse respiratory events when compared to placebo.

Design:
Prospective, multi-centre, triple blinded, randomised control trial undertaken at 3 tertiary paediatric centres in Seoul, Korea. 188 patients enrolled; age 3-6 years having scheduled elective tonsillectomy
- Sample size based based on PRAE incidence in tonsillectomy both with/without inhaled B2 agonist
Exclusions were.
- Recent RTI within 2 weeks
- History of allergic reaction or side effect to tulobuterol patch
- Thyrotoxicosis/hypertension/diabetes/atopic dermatitis/asthma

Intervention:
Patch or placebo applied by parents 8-10 hour pre planned surgery.
Compliance and side effects assessed pre induction.
IV induction with fentanyl/propofol and subsequent muscle relaxation with rocuronium.
Sevoflurane maintenance.
Dexamethasone/Ondansetron and PRN fentanyl at discretion of anaesthetist.
Neostigmine/atropine reversal with extubation occurring when patient awake, train of four ratio > 90% and adequate tidal volume.

Outcome:
Primary outcome was any PRAE from induction to discharge from PACU

For this study PRAE assessed by a blinded anaesthetist and defined as
- Desaturation < 95%
- Airway obstruction – obstruction combined with snoring noise/respiratory effort
- Laryngospasm
- Bronchospasm
- Severe coughing
- Postoperative stridor

Results:
88 in tulobuterol group and 94 in placebo group; from similar demographics
Overall incidence of PRAE:
- Tulobuterol 14.7% vs42.5%
- Relative risk (95%CI) 0.31 (0.17-0.56 p < 0.014)

Of all the assessed PRAE the difference between control and placebo was in airway obstruction and severe cough. There was no difference in the incidence of desaturation/laryngospasm/bronchospasm or stridor between groups.

Summary
In a group of well 3-6 year olds having elective tonsillectomy the application of a tulobuterol patch 8-10 hours prior to scheduled surgery reduced the incidence of airway obstruction and severe cough when compared with placebo.

There was no difference in the incidence desaturation/laryngospasm/bronchospasm or stridor.

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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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