teaser
Joanne Crook MPharm MRPharmS DipClinPharm
Highly Specialist Pharmacist for Women
and Children,
Chelsea and Westminster Hospital NHS Foundation Trust,
London, UK
Sedation is a drug-induced suppression of consciousness that helps relieve anxiety during medical procedures and is a growing necessity in paediatric medicine. It is often used for minor procedures, including peripheral intravenous catheter insertions and minor surgery. In addition to relieving anxiety, sedation can also be useful for medical scans that require children to be still for prolonged periods of time and can be an essential tool for minor procedures where the child may not understand or obey simple instructions.
Striking a balance between ensuring children and young people receive the appropriate tests and investigations and not causing distress through anxiety and pain can be difficult. Once the decision is made to sedate a child for a procedure, the clinician needs to decide which agent to use, how much to give and whether additional pain relief medication is warranted.
Sedation is often unpredictable so it is important to consider any previous drug effects and inter/concurrent illnesses. Poor planning and lack of individual assessments can lead to ineffective sedation which, in turn, might delay procedures and cause unnecessary distress to the child. If too much sedation is given, it can lead to apnoea and respiratory depression; too little can lead to lifetime anxieties for further treatments.
The lack of sedative medication licensing in children has led to a wide scope of practice and is often fraught with the additional risks that prescribing and administering unlicensed medication can bring to patient safety. In order to help reduce this risk the National Institute for Health and Clinical Excellence (NICE) published guidelines for sedation for children and young people in December 2010. The guidelines set out best practice for simple sedation for painless or painful, dental procedures and endoscopies.(1)
Levels of sedation
There are different levels of sedation that can be targeted depending on the nature of the investigation and the child’s needs. Children will range from needing behavioural management alone, through minor sedation, to full general anaesthesia. Currently there is a wide range of methods for choosing the appropriate sedation level, NICE recommends that standardisation of sedation methods will increase both success and safety in children.(1)
Pre-sedation
It is vital to prepare the child and family properly before the event. Information should be offered in order to prepare the child and family psychologically. This should include: what the procedure involves; what is required of the child; and what the healthcare professional will do. Risks and benefits and alternatives to sedation should be explained alongside descriptions of expected sensations (for example, sharp scratch) and how best to cope with the procedure.(1) The information should be age-appropriate and parents should be offered the opportunity to be present. For children with learning difficulties or severe anxiety, specialist opinion should be sought. Play specialists can play an important role in preparing children for certain procedures, using age-appropriate tools to explain techniques (that is, picture story books explaining the procedure)
A trained healthcare professional should assess the child prior to sedation including:(1)
- current medical condition and any surgical problems
- weight
- past medical problems (including previous effects of sedation or anaesthesia)
- current and previous medication, allergies
- physical status (including airway)
- psychological and developmental status (infants and neonates should have specialist input).
The American Society of Anaesthesiologists’ (ASA) physical status classification system can be used to help stratify patients; those patients who are ASA grade 3 or greater will need input from a specialist before sedation takes place (see Table 2).(2)
Who should sedate?
The medical staff skill set required differs depending on the level of sedation and should include knowledge and understanding of, and competency in:
- sedation drug pharmacology and applied physiology
- assessment of children and young people
- recovery care
- complications and management including paediatric life support.
The NICE guidelines lend more weight to the recent movements within the NHS to centralise paediatric services, as it is important to have adequate medical staffing for all planned sedations. Within a paediatric centre this recommendation should not be problematic to implement within normal working hours; however, out-of-hours and within isolated centres or areas, this might be more difficult, especially under current NHS financial pressures.
The life-support skills required in the sedation team are shown in Table 3.
Fasting
The practice of pre-operative fasting aims to minimise residual gastric volume and acidity prior to surgery or other procedures. This helps to prevent regurgitation, inhalation and aspiration of gastric contents. Prolonged periods of fasting are unnecessary and may cause distress, dehydration, biochemical imbalance and hypoglycaemia, especially in children. There is also a tendency for gastric volume to increase after a prolonged fast.(3)
The 2-4-6 fasting rule should be applied for moderate and deep sedation during which the child might not maintain verbal contact with the healthcare professional. Parents should be told prior to the elective surgery to fast their child as follows(1):
- two hours for clear fluids
- four hours for breast milk
- six hours for solids.
Using this rule appropriately can help reduce patient irritability and increase parent satisfaction. Maximum fasting times were not discussed within the NICE guidelines; however, it is important not to fast patients for long periods, especially small infants and babies. Consideration should be given to this when organising the order of patients on surgical lists and intravenous fluids may be required.
Contraindications to sedation(4)
- Recent (<two hours) ingestion of large food or fluid volumes
- ASA Physical class IV or greater
- Lack of support staff or monitoring equipment
- Lack of experience/credentials on part of clinician
- Airway problems or aspiration risk
- Raised intracranial pressure (ICP)
- Severe renal or liver disease
Reversal of sedation
Rarely should reversal of agents used in procedural sedation be necessary if they are titrated appropriately. Flumazenil is a benzodiazepine antagonist that can reverse the effects of benzodiazepine sedation. It has a shorter duration of action than the benzodiazepine agents it reverses, therefore the patient should be monitored carefully and re-dosed if appropriate.(5)
Painless procedures
For painless procedures NICE recommend one of the following sedating medications:(1)
- chloral hydrate (children <15kg)
- midazolam
Choral hydrate is a central nervous system (CNS) depressant (sedative and hypnotic) with no analgesic properties. It is well absorbed from the gastrointestinal tract within 30 minutes of an oral dose, duration of action of four-to-eight hours and distributes widely in the body. It is metabolised hepatically to an active metabolite that is then protein-bound. Elimination is via the kidney but the half-life is variable and can be prolonged in neonates. Adverse effects include gastric irritation, respiratory depression, vasodilation, hypotension, cardiac arrhythmias, CNS depression and paradoxical excitement.(6)
Midazolam is a benzodiazepine that has a relatively rapid onset of action. The onset of action varies with the mode of administration; approximately 30 minutes after an oral dose and 15 minutes for intanasal and buccal administration.(7) Intranasal administration of the injection can cause a burning sensation that might be unacceptable to some children; oral midazolam is bitter to taste, which often needs to be masked. Buccal administration is better tolerated than the intranasal and oral formulations as the volume is small and it is quicker acting.
Midazolam usually has a short duration of action and is a suitable choice of benzodiazepine for day cases. Recovery may be prolonged in neonates and in patients with liver disorders or cardiac insufficiency. Side-effects include gastrointestinal disturbances, hypotension, and respiratory depression.6 Midazolam should not be used if there is a known predisposition to airway obstruction (for example, obstructive sleep apnoea). Paradoxical excitement can also be an issue, especially with children with behavioural disorders; expert advice should be sought in children who have the potential to have, or have had, this reaction.
Sedating antihistamines (for example, alimemazine) were not discussed within the NICE guidelines but they could be a useful second- or third-line agent and are currently in common use for sedation in children. Sedating antihistamines can lower the seizure threshold and should be used with caution in patients who have had recent seizures.(5)
If the above drugs are not suitable, or are not tolerated, then the following may be considered:
- propofol
- sevoflurane.
Propofol in an intravenous anaesthetic that must only be used if the anaesthetist is confident of maintaining the child’s airway. Propofol produces a rapid recovery without a hangover effect and is used widely.5 Side-effects of propofol include convulsions, which can be delayed; therefore the CSM warn of caution after use as a day case. It has also been associated with bradycardia, which can be profound, and antimuscarinics might be required.(8) Propofol is contraindicated for longer-term sedation especially in children who are in intensive care and have metabolic acidosis, cardiac failure, rhabdomyolysis, hyperlipidaemia or hepatomegaly, as this increases the risk of potentially fatal side-effects.(5)
Sevoflurane is a rapid-acting volatile inhaled anaesthetic that gives rapid emergence and recovery. Volatile liquid anaesthetics are administered using calibrated vaporisers using air, oxygen or nitrous oxide–oxygen mixtures as the carrier gas. All inhaled volatile anaesthetics can cause malignant hyperthermia and therefore are contraindicated in patients at risk of this. They can also raise cerebrospinal pressure so should be used with caution in children with raised ICP.(5,6)
Painful procedures
For children and young people undergoing a painful procedure and where the target level of sedation is minimal or moderate, the following should be considered alongside a local anaesthetic:
- nitrous oxide (in oxygen) (Entonox®) and/or
- midazolam (oral or intranasal).
Although not discussed by NICE, some children will be too young for, or will have contraindications to, Entonox. Therefore before automatically going onto the next step as recommended by NICE, the clinician might wish to consider giving alternative analgesics alongside the sedation (for example, paracetamol, low-dose morphine). If opiates are used then additive sedative effects and respiratory side effects should be considered and monitored.
If the above are unsuitable then consider:
- ketamine (IV or IM)
- intravenous midazolam with or without fentanyl (to achieve
- moderate sedation).
For those of whom the above are unsuitable, a specialist sedation technique, such as propofol, with
or without fentanyl, must be considered.
Complications of sedation: prevention and management
Inadequate sedation before the procedure is an all-too common problem. Doses are weight-based, so it is essential to calculate the dose using the most recent weight. Sufficient time should be given for the agents to work. NICE do not advise that a ‘top-up dose’ of sedation is given, because there is the risk that the first dose of sedation has not taken full effect, thereby increasing the risk of respiratory depression. Top-up doses, however, can be useful if advised by a specialist and prescribed in a considered manner; taking into account time to onset and ensuring provisions are made to monitor the child’s airway. Chloral hydrate alone is often not sufficient to sedate a child for a procedure so using this alone with no second-line for failures could lead to increased use of general anaesthesia.
Prolonged recovery from sedation is dependent on several factors, of which the most important are the drug’s volume of distribution and clearance in the individual patient. Be prepared to recover the patient for a prolonged period, with adequate oxygenation and clearance of any airway secretions. Ensure any issues or adverse events which occur with sedation are clearly documented in the patient’s notes to ensure that if sedation is required in the future this can be taken into consideration.
Environment and monitoring
For moderate sedation, depth of sedation, respiration, oxygen saturations, heart rate, pain, coping and distress should be monitored and documented.(1)
For deep sedation, additional monitoring including three-lead electrocardiogram, end tidal CO2 (capnography) and blood pressure is required and documented.
All the above should be age-appropriate and interpreted by a trained healthcare professional. Post-procedure monitoring is essential to ensure patent airway, protective airway and breathing reflexes, haemodynamic stability, and that the patient is easily roused.
In order to safely discharge a child after receiving sedation for a procedure, the following should be ensured(1):
- vital signs are normal
- child or young person is awake with no further risk of further reduced level of consciousness
- nausea, vomiting and pain have been managed adequately.
Conclusions
Sedation can be – and often is – unpredictable, so it is important to consider previous effects of sedation and inter-/concurrent illnesses. Poor planning and lack of individual assessments can lead to ineffective sedation which, in turn, might delay procedures, cause unnecessary distress to the child and increase costs to the NHS. If too much sedation is given it can lead to apnoea and respiratory depression; too little can lead to lifetime anxieties for further treatments.
To standardise the wide scope of practice within the NHS for sedating children, NICE has set out some key recommendations including advice on which agents to use, how to assess and monitor patients and also which staff and what skill sets they require in order to do so. They are a useful benchmark of standards for NHS trusts to aim for. However, in a busy tertiary paediatric centre it is often the more vulnerable children with complex needs who need safe, individualised care rather than standardised treatment. It is therefore vital to have access to specialist paediatric anaesthetists to ensure that all children are sedated in an appropriate manner.
References
- National Institute for Health and Clinical Excellence. CG112 Sedation in children and young people: full guidance. http://guidance.nice.org.uk/CG112/Guidance (accessed 28 February 2012).
- The American Society of Anaesthesiologists’ (ASA) physical status classification system. http://www.asahq.org/clinical/physicalstatus.htm (accessed 28 February 2012).
- Langford R. The preparation of children for surgery. ATOTW132. May 2009. http://www.anaesthesiauk.com.
- Chelsea and Westminster Hospital. Paediatric sedation guidelines;2008.
- Joint Formualry Committee. British National Formulary for Children. BMJ Group. 2010-11.
- Malinovsky J-M et al. Plasma concentrations of midazolam after intravenous, nasal or rectal administration in children. Br J Anaesth 1993 70:617–20.
- Sweetman SC. Martindale: The complete drug reference. Pharmaceutical Press. http://www.medicinescomplete.com/mc/ (accessed 28 February 2012).
- Medicines and Healthcare products Regulatory Agency/Committee on Safety of Medicines. Current problems in pharmacovigilance. June 1992. No 34;Vol 18. www.mhra.gov.uk/Committees/Medicinesadvisorybodies/CommitteeonSafetyofMedicines/index.htm (accessed 28 February 2012).
