Conscious sedation in children

Transcription

1 Michael Sury FRCA PhD Matrix reference 2D06, 3A07, 3D00 Key points Effective sedation techniques are specific to the procedure. Conscious sedation in children can be time-consuming but may save anaesthesia resources. Most effective techniques risk deep sedation, sometimes after the procedure is completed. Sedation failure and complications can be prevented by careful patient assessment. Training of healthcare practitioners is crucial to minimizing patient harm or distress. Michael Sury FRCA PhD Consultant Paediatric Anaesthetist Department of Anaesthesia Great Ormond Street Hospital for Children NHS Trust 40 Bernard Street London WC1N 3JH UK and Portex Department of Anaesthesia Institute of Child Health University College London London WC1N 1EH UK Tel: þ Fax: þ (for correspondence) 152 This article summarizes the principles and practice of effective conscious sedation techniques for common diagnostic and therapeutic procedures in children. It does not cover sedation for intensive care or anxiolytic premedication before anaesthesia. Given that a conscious patient can independently maintain a clear airway and adequate breathing, conscious sedation is safe because the patient remains conscious. Safety of any sedation technique is dependent upon the ability of practitioners to prevent or safely manage deeper levels of sedation. Definitions Consciousness is a continuum in which levels can be recognized. Levels of sedation have been defined by the ASA and they are widely accepted (Table 1). In addition, the term conscious sedation has remained in the UK. It is similar to moderate sedation except that the patient always remains responsive to the spoken word; this definition is used most commonly in dentistry. Conscious sedation Conscious sedation is defined in Box 1. 1 There is a difference between conscious and moderate sedation, but the terms are close enough to make it reasonable to consider them to be equivalent in this article. Ideally, a conscious sedation drug technique should have a margin of safety wide enough to make loss of consciousness unlikely. Box 1 Conscious sedation is defined as: Drug-induced depression of consciousness, similar to moderate sedation, except that verbal contact is always maintained with the patient. Specialist sedation techniques Recently, it has been acknowledged that conscious sedation can be achieved reliably using techniques that have a reduced margin of safety. 2 These are specialist sedation techniques and they risk causing unintended deep sedation or anaesthesia. The incidence of associated airway obstruction and inadequate spontaneous ventilation may be dependent, in the main, on skill and judgement. Basic and advanced conscious sedation in dentistry In dentistry in the UK, conscious sedation techniques are of two types: basic and advanced (formerly known as standard and alternative). 2 Advanced techniques have a reduced margin of safety and should only be used by a specialist team. Background Demand for sedation in children Many children undergoing minor procedures need effective sedation, or anaesthesia, because they are frightened, in pain, ill, or have behavioural problems. Some procedures are very common and anaesthetists should know what sedation techniques are effective and likely to be used by other healthcare practitioners. In children presenting for anaesthesia, occasionally, it may be appropriate to use conscious sedation instead. Sedation is specific to the procedure Four common scenarios, listed in Table 2, require specific sedation techniques. 3 Other procedures require sedation, but the principles of the four common scenarios can usually be applied appropriately. Conscious sedation in children can be time-consuming Children who refuse to undergo a procedure awake are difficult to sedate to the moderate or conscious level. Conscious sedation requires patience, skill, time, and in many circumstances the child has to cooperate during the procedure. Provided the sedation failure rate is sufficiently small, the time investment may be worthwhile and anaesthesia resources can be saved. doi: /bjaceaccp/mks008 Advance Access publication 29 February, 2012 Continuing Education in Anaesthesia, Critical Care & Pain Volume 12 Number & The Author [2012]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please journals.permissions@oup.com

2 Table 1 ASA levels of sedation Sedation level Response to stimulation Associated airway, breathing and cardiovascular effects Minimal sedation Moderate sedation Deep sedation Awake and calm Responds normally to verbal command Cognitive function and coordination may be impaired Sleepy but easily roused Responds purposefully to verbal command or light tactile stimulation Reflex withdrawal from a painful stimulus is not a purposeful response Asleep and not easily roused Responds purposefully to repeated or painful stimulation. None Not appreciable Airway is maintained Spontaneous breathing is adequate Cardiovascular function is usually maintained May be appreciable May require assistance to maintain a patent airway Spontaneous ventilation may be inadequate Cardiovascular function is usually maintained Table 2 Four different common sedation scenarios. *Ketamine sedation is unique and described as dissociative. High-dose ketamine causes anaesthesia and airway obstruction Procedure Example Special issues Painless imaging Painful procedures Gastrointestinal endoscopy Risk of unrecognized deep sedation When a child will not cooperate, it is tempting to increase the dose. In most techniques, for an individual child, it is not possible to be certain what dose or doses can cause deep sedation. It is important therefore to always be prepared for deep sedation. Sedation should only be undertaken where there are the facilities, equipment, and personnel to prevent or manage deep sedation. The pain of some procedures may be brief and may be vulnerable to delayed respiratory depressant effects of potent opioids. Controversy Magnetic resonance imaging Suture of laceration, manipulation of a fracture Gastroscopy and colonoscopy Immobility usually requires the patient to be asleep and not disturbed Use local anaesthesia whenever possible Conscious sedation for cooperative Ketamine is an effective analgesic and immobilizing sedative* Conscious sedation for cooperative Colonoscopy is not usually painful unless the colon is distended Dental procedures Extractions Conscious sedation for cooperative Conservation Local anaesthesia is important Delayed effects of opioids are dangerous The type of drug that can be used safely by non-anaesthetists is controversial. Where anaesthesia services are not available, specialist drug techniques have been used by non-anaesthetists in the UK. Ketamine, for example, is being used by emergency medicine doctors. The recent UK NICE guideline (number 112) 3 recommends: that healthcare professionals using specialist sedation techniques need to be trained to administer sedation drugs safely, to monitor the effects of the drug and to use equipment to maintain a patent airway and adequate respiration. A healthcare professional trained in delivering anaesthetic agents is available to administer sevoflurane, propofol, or opioids combined with ketamine. Guidelines Two UK guidelines are recent. The SIGN guideline concentrates on safe moderate sedation techniques. 4 NICE guideline 112 covers all types of effective sedation, including specialist techniques and recommends a framework of training to use them safely. 3 General principles The following principles of the patient journey are fundamental to the safe delivery of anaesthesia, and also sedation. They are summarized to illustrate how conscious sedation can be delivered effectively, safely, and appropriately. Pre-sedation assessment The psychological and developmental status will help to decide whether a child is likely to cooperate with conscious sedation. Conscious sedation is unlikely to be successful in infants and small children. Likewise, anxious are probably unsuitable unless they are motivated. There are risk factors that may influence the choice of technique and the consenting process. In addition to understanding the current medical and surgical problems, the sedationist should assess the child s growth, previous sedation or anaesthesia, and the Continuing Education in Anaesthesia, Critical Care & Pain j Volume 12 Number

3 drug history. The examination should identify any physical abnormalities, particularly those of the airway. Consent The child and parents should be told what the procedure involves, the proposed sedation, the alternatives to sedation, and the risks and benefits. Written informed consent should be taken. Fasting Fasting is not needed for minimal sedation, sedation with nitrous oxide alone, or conscious sedation using wide margin of safety techniques. Fasting, as for anaesthesia, is recommended for any conscious sedation technique in which verbal contact may be lost. In an urgent situation with a child who is not fasted, the risks of aspiration during the chosen sedation technique should be weighed against the consequences of delay in the procedure. 5 Psychological preparation Much may be gained by spending time preparing a child psychologically. In any event, conscious sedation involves a degree of assent and some explanation will be necessary. The explanation, aided by written information, may cover the procedure, what the child will experience, what they should do, and how they will cope. The parents or carers can help reassure the child and may be helpful during the procedure itself. Personnel and training Healthcare professionals involved should understand and be competent in the technique being used. This should include the pharmacology, applied physiology, patient assessment, monitoring, and care in recovery. They must be able to recognize and manage any complications (see UK Nice guideline 112 for further details). 3 Practitioners should have trained assistants. Clinical environment and monitoring Monitoring is not considered necessary for nitrous oxide alone. For other moderate or conscious sedation techniques, the minimum standard or monitoring is with continuous oxygen saturation and heart rate by pulse oximetry. For specialist conscious sedation techniques, ECG, arterial pressure, and capnography may be needed and should be available. Sedation management and monitoring should be documented. After the procedure, monitoring should continue until there is no risk of further reduced level of consciousness. Any nausea, vomiting, and pain should be adequately managed before discharge. I.V. access I.V. access may be difficult in children and, whenever delivery of i.v. drugs and fluids are unnecessary, or not likely, it may be omitted. For example, i.v. access may not be necessary for nitrous oxide alone, choral hydrate for painless imaging, or for i.m. ketamine. Common scenarios Painless imaging Conscious sedation, in which the child is rousable by verbal command, is unlikely to be successful if the child will not assent to lie still. If the child is anxious, and an anxiolytic is effective, short scans are possible. Usually, however, children fall into two groups: those who can be persuaded to lie still without any sedation and those who need sedation deeper than conscious sedation. In the second group, the sedation technique will only be successful if the child sleeps. It is a mute point as to whether a sleeping child can be roused or not because it is counter-productive to attempt to rouse a child before or during a scan. For this reason, the techniques described here for painless imaging are probably not conscious sedation. Nevertheless, they are included because they may be moderate and their margin of safety is wide. The term safe sleep has been used for these techniques because the incidence of airway obstruction is rare although it is described in large case series. In the author s hospital, a list of contraindications to sedation has been helpful in selecting children in whom anaesthesia is the safer option (Table 3). Table 3 Common contraindications to sedation Airway problems Actual or potential airway obstruction, e.g. snoring or stridor, blocked nose, small mandible, large tongue Apnoeic spells Related to: Brain damage Drug treatment Respiratory disease Sp O2,94% in air Respiratory failure (high respiratory rate, oxygen treatment) Inability to cough or cry High intracranial pressure Drowsiness Headache Vomiting Epilepsy Convulsions requiring rectal diazepam within the last 24 h Rectal diazepam used more frequently than once in 2 weeks Seizure related to sedation Resuscitation within the last month Major neurological or neuromuscular disease associated with, e.g. apnoeic spells or hypotonia Intracranial hypertension Convulsions with cyanosis more frequent than once per day Convulsion,4 h before sedation Failure to regain full consciousness and mobility after a recent convulsion Risk of pulmonary aspiration Abdominal distension of gastric contents Appreciable volumes draining from NG tube vomiting Severe metabolic, liver, or renal disease Requiring i.v. fluids or dextrose Jaundice or abdominal distension Requiring peritoneal or haemodialysis 154 Continuing Education in Anaesthesia, Critical Care & Pain j Volume 12 Number

4 Two common sedation techniques are recommended: 3 Chloral hydrate for children under 15 kg. This oral drug, given in doses up to 100 mg kg 21 (maximum dose 1 g), usually causes sleep within 10 min that lasts for 1 h. Its effect is variable, however, sometimes taking 60 min to sleep onset. I.V. cannulation is not necessary for oral sedation; it may be necessary for contrast media administration. Midazolam. There is little published evidence of the efficacy of this drug in this scenario yet it remains in common use. I.V. doses should be titrated to effect. Starting and increment doses are mg kg 21. The BNFc maximum recommended doses are 6, 10, and 7.5 mg for children aged 1 month 6 yr, 6 12, and yr, respectively. 6 If these are not suitable or effective deep sedation or anaesthesia with propofol or sevoflurane is necessary. Dexmedetomidine, given i.v. in high doses, is also effective at achieving moderate sedation for imaging; 7 it is not available in the UK. Painful procedures In emergency departments and in hospital wards, some painful procedures can be managed using conscious sedation. Wound care and manipulation of fractures are common examples. Minimal sedation can be achieved with: Nitrous oxide. In a maximum concentration of 50% in oxygen, it should be self-administered by the patient. Midazolam (oral or intranasal). Oral midazolam (0.5 mg kg 21 ) is an effective anxiolytic within 30 min. Nasal midazolam (0.2 mg kg 21 ) has an onset as fast as the i.v. route; nasal drops are painful, atomized midazolam is much less so. The buccal route is also useful. Such techniques require patient cooperation. In all cases, a local anaesthetic should be used if possible. Other non-sedative analgesics are important also for pain control after the procedure. When these are not effective, more potent drugs are needed. Two techniques are recommended: 3 Ketamine. The sedative effect is unique and called dissociative ; children are immobile, calm, unreactive to pain yet their eyes may remain open. The state does not fit easily into the ASA levels, nevertheless ketamine is not considered to be conscious sedation. Airway and breathing reflexes are usually maintained but expect a low incidence of laryngospasm caused by airway secretions. Recovery is usual within 90 min. Recommended doses are either 2 mg kg 21 i.v. (give additional doses of 1 mg kg 21 if necessary) or 5 10 mg kg 21 i.m. 8 Midazolam (i.v.) with or without fentanyl (i.v.) can be used to achieve moderate sedation. The doses of both drugs should be titrated carefully and will depend on the degree of pain; a starting dose of midazolam is mg kg 21. The effect of fentanyl may outlast the pain so that once the procedure is over, the fentanyl may cause respiratory depression. A starting dose of fentanyl is mg kg 21. Of the two techniques above, ketamine is more reliable. Even though it causes sedation deeper than the moderate level, it has less respiratory effects, requires less judgement, and less intervention than a combination of midazolam and fentanyl. 9 When either of these techniques is unsuitable, a specialist technique or anaesthesia should be used. Dental procedures The mouth shuts during sleep and therefore, provided a mouth prop is not used, an open mouth is evidence of consciousness during sedation. The pain of dental treatment is notoriously severe and therefore the use of local anaesthesia is important. Once local anaesthesia has been injected and is working, requirements for sedation may be much less. In the UK, dental conscious sedation is divided into basic and advanced (formerly standard and alternative). 3 Standard conscious sedation requires the cooperation of the child and involves one of the two techniques given below. Nitrous oxide is administered via a nasal mask in concentrations up to 70%. Midazolam, titrated i.v. is recommended for anxious adolescent children and young people. A starting dose is mg kg 21. Both of these techniques have an excellent success and safety record. If these sedation techniques are not suitable or sufficient, either an advanced sedation technique or anaesthesia should be considered. Specialist teams are available in some parts of the UK. The specialist techniques themselves involve the use of combinations of potent drugs and there may be a risk, depending on the drugs and their doses, of unintended deep sedation. Endoscopy Some adults can swallow an endoscope or accept the indignity and discomfort of colonoscopy without any sedation. Colonoscopy is uncomfortable but not usually painful except when the colon is stretched, often during biopsy of the terminal ileum. Children, however, almost always require sedation and many prefer anaesthesia. Propofol sedation or anaesthesia, without tracheal intubation, is being used widely but, almost certainly the level of sedation is not conscious. Nevertheless, endoscopy is possible under conscious sedation in many children using i.v. midazolam and an opioid is sometimes necessary. Both drugs should be titrated carefully. In summary, two techniques are recommended: 3 Midazolam i.v. for upper gastrointestinal endoscopy. A starting dose is mg kg 21. Midazolam combined with fentanyl (or equivalent opioid, both i.v.) for lower gastrointestinal endoscopy. A starting dose of fentanyl is mg kg 21. Continuing Education in Anaesthesia, Critical Care & Pain j Volume 12 Number

5 Common pitfalls The following may be helpful to prevent patient harm. Failure to assess the patient Identification of factors that inhibit success or reduce safety should help prevent unnecessary distress or harm. Published lists of common contraindications should be used to help guide the decision about whether anaesthesia is best. Failure to choose the sedation technique appropriate for the procedure Painful protracted procedures in anxious, young, and unprepared children are unlikely to be successful using conscious sedation. A technique that can be converted to deeper sedation is appropriate, provided it can be managed safely. Inadequate training and resources The performance of healthcare practitioners is the vital factor that minimizes patient complications and distress. Training courses, either within local organizations or by specialist colleges and associations, are being developed in the UK. Unrecognized deep sedation Deep sedation from 50% nitrous oxide alone in an otherwise normal healthy patient is extremely rare. Anxiolysis with i.v. midazolam is similarly safe. For all other sedation drugs, the pharmacokinetic and pharmacodynamic characteristics vary and therefore most techniques have an incidence of unintended deep sedation. The risk is dose-dependent. Sedation drugs that have a wide margin of safety are generally not short acting and therefore deep sedation, should it occur, may be prolonged. The following two principles are important: careful titration, not exceeding agreed dose limits. Maximum dose limits, in practice, will depend upon the procedure and patient characteristics and should be agreed locally or by specialist groups. The BNFc provides advice. 6 Flumazenil (10 mg kg 21 ) and naloxone (100 mg kg 21 ) may be necessary for the reversal of deep sedation and respiratory depression effects of midazolam and opioids. Deep sedation after the procedure The pain of a procedure helps to prevent deep sedation and oppose the respiratory depression effects of opioids. Once the pain subsides, either because local anaesthesia has become effective or that the procedure is shorter than the effective length of action of the opioid, respiratory depression is possible. This problem could occur in a recovery area, and staff must be ready to detect and respond. Oxygen treatment Desaturation may indicate sedation deeper than the conscious level. Oxygen treatment may be necessary but is much less important than maintaining patent airway and effective breathing. Capnography should detect problems sufficiently early to prevent oxygen desaturation. Paradoxical excitement Some children are distressed by sedation and increasing doses may not help. Midazolam can cause excitement which may be reversed by flumazenil. Ketamine can cause distressing hallucinations. Sedation by these techniques may need to be abandoned. Declaration of interest None declared. References 1. Royal College of Anaesthetists and Royal College of Radiologists. Sedation and Anaesthesia in Radiology. Report of a joint working party, London, The Royal College of Anaesthetists and the Faculty of Dental Surgery of the Royal College of Surgeons. Standards for Conscious Sedation in Dentistry: Alternative Techniques. A Report from the Standing Committee on Sedation for Dentistry. Available from SCSDAT.pdf, National Institute for Clinical Excellence. Sedation for diagnostic and therapeutic procedures in children and young people. Available from Scottish Intercollegiate GN. SIGN guideline 58: safe sedation of children undergoing diagnostic and therapeutic procedures. Paediatr Anaesth 2008; 18: Green SM, Roback MG, Miner JR, Burton JH, Krauss B. Fasting and emergency department procedural sedation and analgesia: a consensusbased clinical practice advisory. Ann Emerg Med 2007; 49: Royal Pharmaceutical Society of Great Britain. British National Formulary for Children. London: British National Formulary Publications, Royal Pharmaceutical Society of Great Britain, Mason KP. Sedation trends in the 21st century: the transition to dexmedetomidine for radiological imaging studies. Paediatr Anaesth 2010; 20: The College of Emergency Medicine. Guideline for Ketamine Sedation in Emergency Departments. London: The College of Emergency Medicine, Kennedy RM, Porter FL, Miller JP, Jaffe DM. Comparison of fentanyl/midazolam with ketamine/midazolam for pediatric orthopedic emergencies. Pediatrics 1998; 102(4 Pt 1): Please see multiple choice questions Continuing Education in Anaesthesia, Critical Care & Pain j Volume 12 Number