Principles

Sedation is ubiquitous in clinical practice and yet evades a definition that cleanly distinguishes it from general anaesthesia.

The traditional paradigm still promoted by the American Society of Anesthesiologists (ASA) and the UK National Institute for Health and Care Excellence (NICE) guidelines is that of a linear continuum from minimal to moderate to deep sedation and then finally general anaesthesia (see Table 1 ). This model fits well when applied to the classic hypnotic agents that, in various ways, accentuate the neuroinhibitory effects of γ-aminobutyric acid (GABA) in the central nervous system (CNS) such as barbiturates, benzodiazepines and propofol. These typically produce a dose-dependent linear progressive “deepening” in level of sedation culminating in an unambiguous state of general anaesthesia where both respiratory and cardiovascular function are usually overtly compromised.

However, this simplistic framework does not reflect contemporary reality. Single agents most notably ketamine and more recently dexmedetomidine, which each have a different mechanism of action, have been shown to reliably produce profound alterations in consciousness without necessarily compromising cardiorespiratory function. Judicious use of drug combinations can also be used to consistently achieve similar states. As experience and sophistication (e.g. use of target-controlled infusion (TCIs) as well as locoregional anaesthesia) grows it seems that many diagnostic and therapeutic procedures may be carried out safely and effectively without general anaesthesia as traditionally envisaged. The boundary between sedation and general anaesthesia is more blurred than ever.

While some of this work has originated from the anaesthetic literature a large volume of data has orginated from outside the operating theatre especially from North America where children are often sedated for minor procedures by non anaesthetists. The term “procedural sedation” has been used sporadically over a number of years in the sedation literature. More recently a multidisciplinary group (International Committee for the Advancement of Procedural Sedation or ICAPS) has released a consensus definition of procedural sedation ( Box 1 ). The Royal College of Anaesthetists (RCoA) when updating the Curriculum for Specialty training has dropped the title “Sedation” as a Unit of Training in favour of “Procedural Sedation”. The most recent update from the Academy of Medical Royal Colleges acknowledges this new term while choosing to retain the terms mild/moderate/deep sedation for the rest of their guideline. The remainder of this article will embrace the more contemporary definition and conceptual framework.

In truth, the final clinical picture produced by any pharmacological manipulation of the CNS will be a result of the product of a dynamic interaction between the patient, the systemic and regional drugs used and any noxious or other stimuli that occur ( Figure 1 ).

Practice

Routes of administration

• •
  

  Oral administration is usually straightforward in compliant children although midazolam is well recognized as having an unpleasant taste.

  
  
• •
  

  Medications may be given with other drinks, e.g. fruit squash to mask this.

  
  
• •
  

  Onset can be slow and subject to greater interpatient variability than other routes.

  
  
• •
  

  The IN route has been increasingly used in recent years with evidence supporting the use in the Emergency Department setting where fentanyl and diamorphine are often used for analgesia.

  
  
• •
  

  Ketamine, clonidine, dexmedetomidine and midazolam can all be given IN to produce sedation.

  
  
• •
  

  Nasal administration typically has a rapid onset.

  
  
• •
  

  Mucosal atomiser devices enhance drug delivery ( Figure 2 ).

  
  

  
  

  
  

  

  
  

  
  

  Mucosal atomization device. This can be used to enhance efficacy and safety of intranasal administration of some sedatives and analgesics.

  
  
  
  
• •
  

  There are published data supporting the use of IN drugs use for preoperative anxiolysis and one case series describing the exclusive use of the IN route for procedural sedation in children.

  
  
• •
  

  If intravenous sedatives are used it is vital to ensure that there is IV access that is well secured. Constant vigilance is particularly important when continuous infusions are used since any patient movement may result in abrupt loss of access.

Multimodal sedation

• •
  

  The concept of “multimodal analgesia” is well established within the anaesthetic community – give multiple agents acting at a variety of levels to produce greater overall efficacy with lower doses and a lower side effect burden.

  
  
• •
  

  “Multimodal anaesthesia” is a logical extension of these same principles that has been put forward in recent years.

  
  
• •
  

  There is obvious synergy between drugs acting on the CNS and this can be profound – increasing the risks of apnoea etc depending on the agents, the doses, the patient and the clinical context.

  
  
• •
  

  There is evidence that combining drugs can be done safely, efficaciously and with an improved side effect profile compared to using a single agent.

  
  
• •
  

  It makes sense that any sedationist should have a clear theoretical and practical knowledge of the drugs that they are using and administer them in an incremental, patient manner to achieve the appropriate level of sedation/analgesia for the demands of the procedure intended.

  
  
• •
  

  The adage: “it’s not what you do – it’s the way that you do it” rings true.

Non-pharmalogical considerations

• •
  

  This article is aimed at anaesthetists and so has necessarily emphasized pharmacological interventions.

  
  
• •
  

  However non-pharmacological measures are equally important in order to ensure safe procedural sedation.

  
  
• •
  

  Good communication is vital. Clear, confident explanations and reassurance can enable many children to tolerate daunting procedures with no sedation at all. Even if sedation is still required – having the confidence of a child and their parent goes a long way to ensuring success.

  
  
• •
  

  When sedation is being used instead of general anaesthesia this should be made clear to patients and their families.

  
  
• •
  

  Adjuncts such as noise cancelling headphones, music, soft lighting, simple distraction techniques and meditation can also go a long way to minimizing anxiety for patients, parents and healthcare professionals alike. Offering autonomy appropriate to a child’s age and clinical circumstance is often a worthwhile strategy.

  
  
• •
  

  Emotional contagion is a well recognized psychological phenomenon that can tilt an encounter in either a positive or a negative direction. We cannot always control the final outcome but we can create a favourable environment to give ourselves the best chance.

  
  
• •
  

  Distress will sometimes occur despite our best efforts – especially around the time of parental separation or insertion of IV access. It is particularly important to see these patients afterwards to address any concerns they may have. Invariably they are grateful for what has been done but a simple follow-up can still be cathartic for all involved.

  
  
• •
  

  Parental presence during a procedure may sometimes be a better strategy and reduce the need for sedation.

Assessment

This should cover:

• •
  

  Current condition/procedure for which sedation is required

  
  
• •
  

  Previous medical history – especially previous experiences of anaesthesia or sedation

  
  
• •
  

  Current medications

  
  
• •
  

  Functional status

  
  
• •
  

  ASA grade

  
  
• •
  

  Weight

  
  
• •
  

  Psychological and developmental status.

NICE guidelines recommend specialist input in patients who:

• •
  

  Have an airway or breathing problem

  
  
• •
  

  Are ASA 3 or greater

  
  
• •
  

  Infants.

Evidence from the Pediatric Sedation Research Consortium backs this up – examination of a dataset of around 140,000 paediatric sedations found a significantly higher incidence of adverse events in these groups – particularly infants and neonates.

By definition, patients with obstructive sleep apnoea (OSA) tend towards airway obstruction when sleeping so this should be anticipated and there should be a plan in place to manage this if sedation is still contemplated. Obesity, may co-exist with OSA. Independent of this, patients with obesity will also be more likely to obstruct and will drop their arterial oxygen saturations more rapidly when they do. IV access and drug dosing is also more challenging in patients with obesity.

Fasting

Preoperative fasting prior to elective procedures, in order to reduce the risk of regurgitation and aspiration, has been a cornerstone of anaesthetic practice for decades. There has been a progressive softening of this when it comes to “clear fluids” in paediatric anaesthetic practice with an official consensus statement in 2018 reducing it from 2 hours to 1 hour preoperatively. In practice this is already becoming superseded by a “sip to send” policy in a number of institutions.

With regards to urgent procedures things become more nuanced. There is good evidence that aspiration events are rare whether a patient is fasted or not and that fasting may not make a difference. Guidance regarding fasting for non-elective procedures does subtly vary:

“Do not delay procedural sedation in adults or pediatrics in the ED based on fasting time”

“For an emergency procedure in a child or young person who has not fasted, base the decision to proceed with sedation on the urgency of the procedure and the target depth of sedation”

ICAPS has also published their own guideline covering this issue.

Readers are advised to ensure familiarity with both local and national guidelines. Whatever decision is made regarding the need for fasting in a given case – two things are clear – aspiration is rare but remains a risk in all patients, regardless of fasting status. All practitioners giving sedation should remain vigilant.

Fasting is not required for:

• •
  

  Minimal sedation

  
  
• •
  

  Nitrous oxide use (as a sole agent)

  
  
• •
  

  Moderate sedation during which verbal contact is maintained

Monitoring

Non-theatre setting

The vast majority of paediatric sedation occurs outside the operating theatre. Guidelines for the Provision of Anaesthetic Services (GPAS) emphasize that “irrespective of the site of care delivery (theatre or non-theatre), children should receive the same standard of anaesthetic care or sedation as applied to procedures performed in theatre”.

Being “free” of the requirement of an anaesthetic machine does significantly increase the flexibility for procedural sedation to be performed in the non-theatre setting which may allow for more efficient and timely care for patients. But, as stated in the GPAS guidelines, this should not compromise safety. Practitioners should properly familiarize themselves with the equipment and environment. They should check that vital equipment such as suction is available and functioning. They should also be clear how to get further help should an adverse event occur and consider how long this may take to arrive. Checklist use can help ensure confidence in this.

Conclusions

Sedation remains ubiquitous in paediatric practice. Modern drugs and delivery techniques provide an opportunity to provide effective and safe procedural sedation for a wider range of diagnostic and therapeutic procedures in a wider range of settings. Since procedural sedation may be performed by different specialties, descriptions of what constitutes acceptable practice can vary. Individual practitioners should have an awareness of the issues involved and be confident in their ability and that of the system that they are working in to anticipate and deal with adverse events in order to provide safe procedural sedation for children.