Sedation and analgesia in children

Chapter 100 Sedation and analgesia in children



All children, including preterm infants, feel and remember pain and discomfort.1 Provision of adequate sedation and analgesia should therefore be a priority in the management of all critically ill children.




ASSESSMENT


Adequacy of pain relief and sedation is dependent on an accurate assessment of the degree of discomfort. This is particularly difficult in the critically ill child who may be preverbal, developmentally delayed, intubated and/or paralysed, or simply uncooperative. Thorough assessment requires careful and frequent consideration of a number of factors. These include the nature of the noxious stimulus, variations in physiological parameters (e.g. heart rate and blood pressure) and interpretation of subjective clues (e.g. facial expressions and posture). Parental interpretations are reliable and should be included in the overall assessment.


Pain and sedation assessment tools should also be utilised. Neonates and infants are particularly difficult to assess and validated assessment tools, including the Premature Infant Pain Profile (PIPP) and CRIES scale, are helpful objective measures of pain in this group.5 The Multidimensional Assessment of Pain Scale (MAPS) has recently been validated as a tool for assessing postoperative pain in preverbal children.6 Established tools such as the Face, Legs, Activity, Cry and Consolability (FLACC) Scale have been modified to enhance the pain assessment of children with cognitive impairment.7 The COMFORT and the modified COMFORT ‘Behavior’ are validated observer reported sedation scales for children 1–3 years.8 In older children, self-reporting measurement scales can be used but these require a degree of patient cooperation.


The most challenging group of patients to manage optimally are those receiving muscle paralysis. Attempts to enhance the limited clinical parameters available for interpretation with an objective measure have centred on the bispectral index (BIS). Validation studies in the paediatric intensive care environment are limited and highlight the probable inaccuracy of current methods of assessing sedation in paralysed patients.9 In general it is preferable to err on the side of over- rather than undersedation in the paralysed patient.



APPROACH TO MANAGEMENT


The management of discomfort, anxiety and pain should be multifaceted. Recently published consensus guidelines from the United Kingdom Paediatric Intensive Care Society present a detailed analysis of the evidence for assessment and management strategies.10


Management can and should, whenever possible, begin prior to the child’s admission to intensive care. Orientation to the unit should be accompanied by a clear, age-appropriate explanation of the planned procedure or operation and the expected postoperative course. Parental presence during this phase and at other critical times is also important to help allay anxiety and fear. Close attention should also be paid throughout a child’s admission to potentially distressing physiological factors, such as hunger and urinary retention. In addition to these supportive measures, many paediatric patients require a pharmacological form of analgesia or sedation.


Sedation and analgesia should be tailored to the patient’s particular requirements. It is vital that there be continuous assessment and frequent adjustment of regimes so that optimal levels of sedation and adequate analgesia are delivered at all times. This requires a clear understanding by medical and nursing staff of the aims of management and of the pharmacology of the agents being administered. Relief of pain should be achieved with analgesic agents and care must be taken to avoid the overadministration of sedative agents when the patient’s primary need is for pain relief (Table 100.1). While emphasis should be on optimal comfort, consideration should also be given to minimising side-effects. A single drug may be effective but often a combination of medications and a combination of delivery methods (e.g. i.v./oral, i.v./epidural) will be useful and may avoid the side-effects of high doses of a single agent. A recent trend towards analgesia-based sedation, as an approach to managing the ventilated adult patient, has shown benefits when compared to hypnotic-based regimes.11


Table 100.1 Single dose and infusion rates of sedative and analgesic drugs*













































Drug Bolus dose Infusion rate
Morphine 0.1–0.2 mg/kg i.v. 10–40 μg/kg per hour
Fentanyl 1–2 μg/kg i.v. 1–10 μg/kg per hour
Remifentanil 0.1–0.5 μg/kg i.v. 0.1–0.5 μg/kg per min
Midazolam 0.1–0.2 mg/kg i.v. 50–200 μg/kg per hour
0.5 mg/kg (oral)
Ketamine 1–2 mg/kg i.v. 10–20 μg/kg per min (sedation)
4 μg/kg per min (analgesia)
Propofol 1–3 mg/kg i.v. < 4 mg/kg per hour (short term)
Clonidine 1–2 μg/kg i.v. 0.1–2 μg/kg per hour
4 μg/kg (oral)
Dexmedetomidine 0.5–1 μg/kg i.v. 0.2–1.0 μg/kg per hour

Note: Some infusion rates are described per minute and others per hour.




NON-OPIOID AGENTS



MIDAZOLAM


Midazolam is water soluble, and has a rapid onset of action. Metabolism occurs in the liver and by 6 months of age is comparable to that of an adult. The standard i.v. sedative dose is 0.1–0.2 mg/kg and this is effective for uncomfortable procedures, such as echocardiography and cardioversion. The oral route (0.5 mg/kg) may also be useful though there is a 15-minute delay to onset of sedation. Nasal administration (0.2 mg/kg) can be useful in children who do not have established i.v. access and in whom oral agents are not appropriate. Although midazolam may be effective as the sole sedative agent for ventilated patients, higher doses, and often additional agents, are commonly required in young children (1–4 years).12 50–200 μg/kg per hour, in combination with an opioid (morphine 10–40 μg/kg per hour), is usually effective in facilitating mechanical ventilation. Dose-related respiratory depression occurs and hypotension can be significant in hypovolaemic patients and in those with depressed myocardial function. During continuous infusion, accumulation can occur, particularly in young infants (under 6 months) and in patients with liver dysfunction. The use of midazolam in neonatal intensive care is controversial as there are concerns regarding its safety and effectiveness as a long-term sedative in the newborn.13




PROPOFOL


Propofol is a rapidly acting hypnotic agent that is widely used in paediatric anaesthesia and intensive care for short- and longer-term sedation.16,17 Although it has no analgesic properties its short half-life makes it an attractive agent for sedation. The half-life decreases with age, probably due to development of metabolising capacity and increasing hepatic flow.18 Sedation can be achieved in the spontaneously breathing patient, with an induction dose of 1 mg/kg, followed by intermittent smaller doses: 2–3 mg/kg per hour has delivered uncomplicated satisfactory sedation to ventilated children.19 However, propofol should be used with caution for sedation in the PICU because of the reported association between high dose (> 4 mg/kg per hour), prolonged (> 29 hours) infusions and a clinical syndrome (propofol infusion syndrome) consisting of metabolic acidosis, lipaemia, cardiac failure, arrhythmias and death.20 The pathogenesis of this syndrome remains unclear, although it has been postulated that a disturbance of mitochondrial function leading to disordered hepatic lipid regulation underlies the disorder.21 Lipaemia may be an early indicator of developing problems and successful use of haemodialysis in the early phase is the only therapy described.22 There are sufficient concerns to limit the use of propofol in the PICU to short-term sedation in the stable ventilated child. Administration of propofol in the presence of shock, hypoxaemia or acute liver dysfunction, or for long-term, high-dose sedation cannot be recommended. It should be noted that the manufacturers advise against the use of propofol for sedation of children during intensive care.


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Jul 7, 2016 | Posted by in CRITICAL CARE | Comments Off on Sedation and analgesia in children

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