novice guide to paediatric anaesthesia
TRANSCRIPT
Paediatric Anaesthesia for Beginners
Dr Tom Lawson Edited by Drs S.Rawlinson and R.Langford Adapted for the APA from a guide mapped from RCoA Basic Level Curriculum currently in use in the Peninsula Deanery
!2!
General Disclaimer The materials and other information provided within ‘Paediatric Anaesthesia for Beginners’ are for educational, communication and information purposes only and are not intended to replace or constitute medical advice or treatments. The author intends and has taken care to confirm that the information presented, herein is accurate at time of press and describes generally accepted practices. However, the author(s), editor(s) and publisher(s) accept no responsibility for errors, omissions, or for any consequences from application of the information within the book and disclaim any warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of this publication. The use of the information contained within, in a particular situation remains the professional responsibility of the practitioner; any clinical treatments described and/or recommended may not be considered absolute and universal recommendations, only the approach or opinion of the author. The author(s), editor(s) and publisher(s) have exerted every effort to ensure that drug selection and dosage contained herein are in accordance with current best practice at the time of publication. However, in view of the changing nature of anaesthetics and medicine, along with changes in government regulations the reader is urged to check the British National Formulary (BNF) or package insert for each drug for any change in information.
The information and action plans contained within are meant only as a guide and do not reflect a particular method endorsed by the APAGBI Correspondence Dr Tom Lawson – Speciality Registrar Peninsula Deanery Email: - [email protected]
! 3!
Contents Page • Definitions 4 • Normal Physiological Values 4 • Formulae 5 • Paediatric Physiology 6 - 9 • Premature Infant Physiology 10 - 11 • Paediatric Anaesthesia 12 • Pre-operative Assessment 12
o General Tips 12 o Psychology of Children 12 - 13 o History 14 o Immunisation 15 o Fasting 16 o Examination 16 o Consent 17 o Explanation 18 o Children with additional or special needs 19 o Child Safety 20 - 21 o Pre-medication 22 o The Ill-Child at Pre-assessment 23
• The Anaesthetic Room and Induction 24 o Patient Positioning 24 o Distraction and Cannulation 25 o Intra-Osseous Access 26 o Monitoring 26 o Inhalation and Intravenous Induction 27 - 28 o Airway Manoeuvres, Equipment and Laryngoscopy 29 - 32 o Difficult Airway Society Algorithms 33 - 35
• Four Common Peri-operative Problems 36 • Peri-operative Fluids & Glucose 36 • Emergence and Extubation 37 • Recovery 37 • Breathing Systems 38 – 39 • Paediatric Regional Anaesthesia 40 • Paediatric Pharmacology 41 • Drugs used in Paediatric Anaesthesia 42 – 44 • PONV 44 • Critical incidents 45 – 56
o An Approach to Paediatric Emergencies 45 o Resuscitation Council Choking Algorithm 46 o Resuscitation Council Cardiac Arrest Algorithm 47 o Anaphylaxis 48 o Acute Asthma 49 o Stridor and Acute Airway Obstruction 50 o Arrhythmias 51 o Laryngospasm 52 o Bleeding Tonsil 53 o Seizure and Hypoglycaemia 54 o Paediatric Sepsis 55 o Resuscitation Council Neonatal Life Support Algorithm 56
• Curriculum Mapping 57
!4!
Definitions • Premature = Less than 37weeks • Extreme Prematurity – Less than 28weeks • Neonate = up to 44weeks from date of conception
o Post-conceptual age = gestational age at birth + post-natal age o Low birth weight = Less than 2500g o Very low birth weight = Less than 1500g o Extremely low birth weight = Less than 1000g
• Infants = 1month to 1 year • Child = 1-12 years • Adolescent = 13-16 years
Different Age Groups and Physiological Parameters
Neonate
Infant
Child
Heart Rate 110 - 160 95 -140 80 - 120 Resp Rate 30 - 40 25 - 30 20 - 25 Systolic BP 50-60 80 - 100 90 - 110 Tidal Volume 7 - 8ml/kg 7 - 8ml/kg 7- 8ml/kg FRC 30ml/kg 30ml/kg 30ml/kg Dead Space 2ml/kg 2ml/kg 2ml/kg Blood Volume 90 ml/kg 80 ml/kg 70 - 80ml/kg Hb 11 - 18 11 - 13 11 - 13
! 5!
Formulae • There are several important formulae that you will need to memorize. • It is worth doing them for each patient you anaesthetise so that they become
second nature Resuscitation
• Weight (kg) o All purpose = (Age in years + 4) x 2
Tends to underestimate weights o APLS Age specific
<1 year = (Age in months x 0.5) + 4 1-5 years = (Age in years x 2) + 8 6 -12 years = (Age in years x 3) + 7
• Electricity = 4J/kg • Tracheal tube
o Uncuffed size = (Age/4) + 4 o Cuffed size = (Age/4) + 3.5 o Length = (Age/2) + 12 (oral) or 15 (nasal)
• Fluid bolus = 20ml/kg (or 10ml/kg if trauma or cardiac concerns) • Adrenaline = 10mcg/kg = 0.1ml/kg of 1:10,000 or 0.01ml/kg of 1:1000 • Glucose = 2ml/kg of 10% Dextrose
Physiological Parameters
• Approximate Systolic BP = 80 + (age x 2) • Neonates are exceptions to this – Systolic BP = 50-60mmHg
Fluid Formulae
• Bolus = 20ml/kg (or 10ml/kg if trauma or cardiac concerns) • Normal Hourly Maintenance Requirement
o 4ml/kg for first 10 kg o 2ml/kg for second 10kg o 1ml/kg for every additional kg
I.e. a 22kg child will require 62ml/hr (40ml for 1st 10kg, 20ml for 2nd 10kg and 2ml for the remaining 2kg)
• Normal Daily Maintenance Requirement o 100ml/kg for first 10kg o 50ml/kg for second 10kg o 20ml/kg for every additional kg
• Nil By Mouth Deficit o = Hourly requirement x number of hours NBM
• Dehydration Definitions o Dehydration without shock = <10% fluid loss slow replacement o Dehydration with shock = >10% fluid loss rapid replacement o Replacement fluid (ml) = % dehydrated x weight (kg) x 10
• Blood o Transfusion (ml) = 4 x weight (kg) x Desired rise in Hb o I.e. if Hb is 8g/dl and you want it to be 10g/dl
Transfusion (ml) = 4 x weight (kg) x 2
!6!
Paediatric Anatomy and Physiology Airway Anatomy
• Neonates / Infants • Head and Neck
o Large Head with prominent occiput pillows are unhelpful as they may position the head and neck in a way to obstruct the airway
o Relatively larger tongue easier to obstruct the airway o Short Neck and Small Mandible o Obligate nose breathers when <5months – narrow nasal passages.
• Larynx o Floppy U-shaped epiglottis lifted out of the way on
laryngoscopy o More anterior and cephalad larynx (C4) hence moving head
more anterior (‘sniffing the morning air’ will not help during laryngoscopy)
o Cricoid ring = narrowest part of the upper airway easy to damage mucosa if ETT is too tight
• Trachea o Short trachea (from cricoid to carina) easy endobronchial
intubation o Soft tracheal cartilage – can collapse with negative inspiratory
pressure • Lungs
o Bronchi at same angles bronchial intubation as likely on both sides
o Higher airway resistance (nasal passages are responsible for 50%) • Chest
o Horizontal ribs no bucket handle movement increased work of breathing
o Weak respiratory muscles easy to fatigue if work of breathing is high
o Diaphragm dependent ventilation any limitation of diaphragmatic movement has a large effect e.g. bowel obstruction
• Toddlers • Head and Neck
o Head is more proportional to body size o Baby teeth begin to erupt (permanent teeth begin to erupt from
6years) o Jaw becomes larger
• Larynx o Epiglottis Is less floppy and may not need to be lifted on
laryngoscopy • Chest
o <7 years the diaphragm Is the main muscle of respiration
! 7!
Respiratory • Neonates / Infants
• Immature respiratory centres apnoea risk up to 60 weeks post-conceptual age hence give opioids with care
• Lower airway compliance (stiff lungs) – but compliant chest wall • High Respiratory Rate • Higher closing volume risk of hypoxaemia • Small O2 reservoir, high metabolic rate + oxygen consumption rapid
desaturation Cardiovascular
• Neonates / Infants o Sinus arrhythmia is common o Stiff, poorly compliant ventricles with less contractile elements o Reduced contractility o Limited Starling Response fluid overload can result in heart failure o Rate dependent cardiac output o HR <60bpm = unable to support cardiac output o High Vagal tone prone to bradycardia
• Toddlers o HR decreases o Systolic BP rises
• School Age and above o Systolic BP increases o HR decreases o Increased Blood Volume o Heart approaches full size
Neurological
• Neonates / Infants o General
Immature sympathetic nervous system high vagal tone Incomplete myelination complete by age 2 Pain pathways are intact and functional
o Brain Immature BBB (more permeable) Higher cerebral metabolic rate, O2 and glucose requirement Cerebral blood flow = 50ml/min/100g CSF volume = 4ml/kg Skull sutures are open
o Spinal Cord / Column Spinal cord ends at L3 at term, L2-3 at age 1 Intercristine line = L5/S1 Thin sacrococcygeal membrane
• Toddlers o Parasympathetic and sympathetic activity more equal o BBB fully formed o Cerebral blood flow = 100ml/min/100g o Spinal cord terminates at L1/2 at 8 years
• School Age and above o Fully developed nervous system by mid-adolescence o Cerebral blood flow = 50ml/min/100g
!8!
Hepatic / Renal / Gastrointestinal • Neonates / Infants
o Hepatic Ductus Venosus = patent for 7-10days post-birth Phase 1 + 2 reactions are normal from 2-3months Low hepatic storage reserves of platelets, glucose and bicarb
can lead to coagulopathy, hypoglycaemia and acidosis o Renal
Full number of nephrons are present at birth, however, they do not have full filtering / concentrating ability until 2-3months
High renal vascular resistance at birth falls at week 2 – 4 Low Renal Blood Flow at birth rises at week 2-4 Low GFR at birth adult levels by 1 year
o Higher total body water than in older children 80% in the neonate The proportion of ECF to ICF differs ECF decreases with age, whilst ICF increases with age.
• Toddlers o Frequent stomach upsets o Calorific requirement less than in infancy / adolescence o Better blood glucose control than in infancy
• School Age and above o Stomach upsets less frequent o Stomach size and capacity at adult levels by 14 years of age
Musculoskeletal
• Neonates / Infants o Immature musculature easy to fatigue
• Toddlers o Increased bone and muscle growth o Incomplete bone mineralisation o Immature musculature easy to fatigue
Thermoregulation
• Neonates / Infants o Immature hypothalamus o Increased body surface area: weight o Increased basal metabolic rate o Poor insulation – thin skin, low fat and immature muscles
Reduced ability to shiver and produce endogenous heat o High vagal tone less able to vasoconstrict o Non-shivering thermogenesis
Brown fat = fat with high number of mitochondria (large iron content makes it brown)
Noradrenaline stimulates triglyceride oxidation utilises oxygen and glucose to generate heat_
Poorly efficient
! 9!
Immunological • Neonates / Infants
o Reduced ability to synthesize Ig’s at adult levels by 1 year o ABO antibodies appear by 2months
• Toddlers o Immune system immature
• School Age and above o Lymphatic tissue at peak from age 10-12 o Then regresses to adult levels
Haematopoietic
• Neonates / Infants o 80% of total Hb at birth = HbF falls to 5-10% by 4months o HbF shifts Oxy-Hb curve to the left (alkalosis is bad) o Hb = 18g/dl at birth 11g/dl at 3months o Blood volume = 100ml/kg for prems, 90ml/kg for neonates o High lymphocyte and leucocyte count
• Toddlers o Blood volume = 80ml/kg
• School Age and above o Blood volume = 70ml/kg o Normal adult values
Endocrinological / Metabolic
• Neonates o Lower glycogen stores o Immature pathways for gluconeogenesis o Therefore hypoglycaemia occurs more easily and is less well tolerated
!10!
Premature Infants • The overarching consequence of prematurity is that there is incomplete organ
development at the time of birth and this is associated with increased morbidity and mortality.
• Respiratory • General
o Chronic Lung disease is common in very-low birth weight infants o Increased susceptibility to respiratory infections
• Apnoea of Prematurity o = Pause in breathing of >20secs or o = Pause in breathing of <20secs with bradycardia +/- cyanosis o Prem/neonatal Response to hypoxia
= Brief hyperventilation apnoea + blunted response to hypercapnia
Typically returns to normal by 3weeks, this may take longer in prems – up to 60weeks post-conceptual age.
This is of key concern in ex-premature infants. Ideally elective surgery should be delayed
o Respiratory Distress Syndrome
Inadequate surfactant production before 32-34weeks Antenatal corticosteroids in preterm labour stimulates surfactant
production and reduces incidence Surfactant may need to be given after birth
o Bronchopulmonary Dysplasia Affects neonates that receive oxygen / mechanical ventilation
for >28days Features include oxygen dependency, hypoxia, hypercarbia,
etc Results in reduced lung compliance, increased oxygen
requirements and reversible airway obstruction o Respiratory Tract injury
Related to the number/duration of tracheal intubation(s) Increased incidence of acquired subglottic stenosis
• Cardiovascular o Patent Ductus Arteriosus
Usually closes within 3-4days in 90% of well prems Results in increased pulmonary blood flow, worsening RDS,
cardiac failure and low diastolic pressure Medical closure with Indomethacin Surgical closure in failed medical treatment / NSAID
contraindication o Difficult venous access
! 11!
• Nervous System o Development of Pain Pathways
Precise gestational age when a neonate can perceive pain is UNKNOWN
Although at 26weeks gestation – prems respond to tissue damage by withdrawal + stress response
o Other common problems include: - Intraventricular Haemorrhages and Retinopathy of prematurity + Oxygen Toxicity
• Hepatic / Renal / Gastrointestinal o Common problems: - Gastro-oesophageal reflux and Necrotising
Enterocolitis o Renal function depends on gestational age
• Thermoregulation / Metabolic o Lower brown fat deposits compared to neonates o Glycogen stores / Gluconeogenesis pathways are underdeveloped
• Haematopoietic o Hb concentration may be lower than at term (13-15g/dl versus 18-
20g/dl
!12!
Paediatric Anaesthesia • The keys principles are PREPARATION and FLEXIBILITY.
o This ranges from establishing a rapport with a child and their parents to knowing emergency drug doses.
• There are also a few important differences from adult anaesthesia to remember
Induction
• Lower FRC more rapid desaturation • Higher minute ventilation faster uptake of inhalation agent • Neonates and babies have an increased predisposition to apnoea
Intubation
• Increased risk of bradycardia due to higher vagal tone • Higher risk of laryngospasm and hypoxia
Maintenance
• MAC varies depending on age • If breathing spontaneously changes in inspired concentration of inhalational
agents rapidly affect child Emergence
• Higher metabolic and respiratory rates lead to more rapid emergence • Risk of bradycardia and laryngospasm is the same as at induction
Pre-operative Assessment
• This is your opportunity to make life easy for yourself. • It is also often the part of the anaesthetic that most trainees have difficulty with. • Being able to win over a shy or sceptical child is critical and will make the
induction more pleasant for the child, their family and yourself. • It is also important to flag up the potentially difficult child early e.g. to give
enough time for pre-medicants to work. General Tips
• Smile • Be happy, pleasant and non-threatening • Take an interest in the child or what they are doing e.g. what toys they are
playing with or characters on their clothing • Try to stay at eye-level with the child • Talk to the child first and foremost, but also try to involve the parents. • USE APPROPRIATE LANGUAGE – the following are suggestions: -
o Anaesthetists = Sleep doctors o Anaesthetic = a special sleep o Venflon / Cannula = Straw o Ametop = Magic Cream o Propofol = Penguin (cold) or Hedgehog (prickly) milk o Facemask = Space mask
Psychology of Children
• Children are, obviously, psychologically different to adults • They change rapidly with age (outlined in the table on the following page).
!13!
!14!
History • Past anaesthetics – Problems and Family History • Presenting Complaint
o Timing of injury – this is especially relevant in trauma o Pain – recent analgesics o Any nausea or vomiting
• Past medical history including: - o Neonatal history o Congenital syndromes and cardiac disease o Asthma or Cystic Fibrosis o Epilepsy o Developmental disorders, Trisomy 21, Cerebral Palsy, etc
• Recent coughs / colds / upset stomachs / vaccinations (see below) • Drugs and Allergies
o Latex – including risk factors e.g. Spina Bifida • Loose teeth
History Specifics Airway Syndromes
• Chonal Atresia = congenital atresia of passage from nose to pharynx (uni or bi-lateral)
• Pierre-Robin = Congenital anomaly of jaw (retrognathia)/ tongue / palate) with obstruction when supine, Difficult intubation that reduces with age as mandible grows
• Treacher-Collins = Autosomal dominant disorder with retro-gnathia results in Difficult intubation that reduces with age as mandible grows
• Mucopolysaccharidoses (E.g. Hurley’s or Hunter’s) = intralysosomal accumulation of glycosaminoglycans stiffening of soft tissues difficult intubation increases with age
• Laryngomalacia = unusually soft cartilaginous structures dynamic obstruction – Usually resolves over first 6months of life
Congenital Cardiac Disease
• Thorough understanding of underlying anatomy / physiology is key • Look for evidence of the Four major complications of Congenital Heart Disease
o Arrhythmias o Cardiac Failure o Cyanosis o Pulmonary Hypertension
• Other considerations o What are the O2 saturations in air o Is there failure to thrive o Does PVR or SVR require manipulation o Any chest infections? o Venous access issues o Need for Endocarditis prophylaxis
! 15!
Immunisation • APA recommendations on timing of vaccinations are: -
o Pre-Assessment Continue normal vaccination schedule in line with below Risk assessment should involve vaccine side effects in context of
recovery period o Surgery following Inactivated Vaccines
Delay procedure for 48hours to avoid vaccination symptoms causing diagnostic uncertainty post-operatively
o Surgery following Live Attenuated Vaccines If child is well at pre-op assessment, no need to delay
procedure o Vaccination post-surgery
As long as child has recovered from procedure and is well, there is no contraindication to immediate vaccination.
• NHS vaccination schedule is shown below: -
Age Vaccines offered Vaccine Vaccine Type DTaP Toxoid Inactivated IPV Inactivated Hib Subunit/Conjugate PCV Subunit/Conjugate
2 months 5in1 = DTaP / IPV / Hib PCV Rotavirus
Rotavirus Live attenuated 3 Months 5in1 = DTaP / IPV /
Hib 2nd dose Men C Rotavirus 2nd dose
Men C
Inactivated
4 months 5in1 = DTaP / IPV / Hib 3rd dose PCV – 2nd dose
12 - 13months Hib / Men C Booster MMR PCV – 3rd dose
MMR
Live attenuated
3 years 4 months
MMR – 2nd dose 4in1 = DTaP/IPV – pre-school booster
12-13years (girls only)
HPV vaccine (3jabs in 6months)
HPV Subunit/Conjugate
13-18years 3in1 = Td/IPV booster Men C booster
Td Toxoid Inactivated
• DtaP = Diphtheria / Tetanus / acellular / Pertussis • Hib = Haemophilus Influenzae type B • IPV = Inactivated Polio Vaccine • PCV = Pneumococcal vaccine • Men C = Meningitis C • MMR = Measles / Mumps / Rubella • HPV = Human Papilloma Virus
!16!
Fasting • Prolonged fasting in children can cause distress, dehydration, biochemical
imbalance and hypoglycaemia. • Gastric volume may even increase after a prolonged fast • Younger children have smaller glycogen stores • Cerebral glucose requirement is higher in children. Therefore hypoglycaemia
can more easily result in neurological damage.
Food / Drink Minimum acceptable Fasting Time Clear Fluid 2 hours Breast Milk 3 hours Formula Milk if child <1year 4 hours Food and Cows Milk 6 hours Examination
• Often difficult due to lack of understanding / cooperation • Where possible do an airway assessment – if you have any concerns discuss
with the consultant • Auscultate the chest – for chest signs (e.g. wheeze) or murmurs. • Look for potential veins for cannulation if ametop hasn’t been applied.
What if you detect a new murmur?
• You need to determine whether it is likely to by innocent or pathological and discuss with the consultant
Murmurs in Children Innocent Pathological Usually systolic Pansystolic or Diastolic Quiet Loud No Thrills Thrills present No associated signs/ symptoms Associated cardiac signs / symptoms Normal exercise tolerance or growth Abnormal exercise tolerance / growth No cyanotic episodes Cyanotic Episodes
! 17!
Consent • Consent should be obtained from the adult with parental responsibility for the
child and where appropriate, from the child themselves. • Use language the child can understand • Age and Competence
o In the eyes of the Law anyone under 18years of ages is deemed to be a child
o Children between 16 and 17years of age are presumed to be competent to consent to treatment – although this does NOT invalidate a parent’s right to consent on their child’s behalf
o Children under 16years of age are presumed not to be competent unless deemed ‘ Gillick competent’ by a doctor
o If under 16 Gillick competence may need to be assessed • Gillick Competence
o Refers to specific legal case examining whether doctors should be able to give contraception advice to under 16year olds without parental consent
Gillick v West Norfolk and Wisbech AHA (1985) Fraser Guidelines
o General principles of consent apply Understanding Weighing up pros and cons Arrival at a decision Recall of information
• Incompetent Children o Consent may be given by parents, temporary carers, local authorities
or the courts – as long as treatment is in best interests • Life-threatening conditions
o Parental consent should be obtained wherever possible o But doctors may act in child’s best interest to safeguard child’s
life/health
!18!
Explanation • Often best to describe both IV and Inhalation induction as the 1st and 2nd
options • Explain that one parent can accompany them to the anaesthetic room • Written consent is not routinely required for general anaesthesia or related
procedures o It must be taken however for general anaesthetics for MRI or CT scans
IV induction
• Things to explain to child o Take off the plaster and wipe away the magic cream o Put a little plastic straw in and stick it down o Give you some penguin or hedgehog milk to give you a nice sleep
• Things to explain to parents o Risks are the same as for adults – except for vomiting and
laryngospasm. o Failure to site cannula and need to proceed to inhalation induction
Inhalation Induction
• Things to explain to child o Give you a little space mask to hold
If the child is nervous it might be a good idea to bring a mask with you to pre-assessment get them to play with it before hand
o Show them your balloon and explain you want them to try and blow it up and then suck all the air out of it – try to make it into a game
o Gradually you’ll drift off into a nice sleep • Things to explain to parents
o Children may become distressed and fight the mask – explain that when a child does this, they take deeper breaths and will often go to sleep more quickly
o Children may become ‘floppy’ all of a sudden – this is normal o Children may twitch or make strange movements whilst they are asleep
– this is normal also Post-Operative Psychological Problems
• Children are vulnerable to psychological problems as a result of a difficult induction of anaesthesia.
• These will make subsequent visits to the anaesthetic room, or healthcare in general, more difficult.
• Hence the need for preparation and flexibility and why restraint during induction should be avoided wherever possible.
• Risk factors include: - o Age 2 – 3 o Pre-operative withdrawn behaviour o Difficult and stressful induction e.g. violent inhalation induction o Multiple previous procedures
! 19!
Children with Additional or Special Needs • Coming into hospital is strange and potentially frightening event for children,
this can be more so with children with learning disabilities (LD). • There is a spectrum of LD and there many associated conditions, including: -
Austic Spectrum, Down’s Syndrome, Cerebral Palsy, etc • Such children pose unique challenges that require a flexible and holistic
approach. Such challenges include: - • Cognitive
o IQ is not always low o May find it difficult to: -
Understand what is being asked of them Make themselves understood Remember things Understand other people’s perspectives Adapt to new or unfamiliar situations Understand metaphors / fantasy – Autistic Spectrum children
are very literal thinkers Distinguish between appearance and reality
• Behavioural o May not like being touch or having eye-contact o May be non-verbal or excessively verbal o May have a limited range or interests, preferred foods/drinks, etc o May show signs of repetitive or ritualistic behaviour o May lack coordination o May find it difficult to pay attention
• Emotional o May become anxious or sad o May become uncooperative / aggressive
• Social o May find it difficult to interact with other people o All of the above can impact on feeding, hygiene, dressing, transport,
etc. o Attending hospital appointments poses a logistical challenge for carers
• General Management Principles o As with everything else in paediatric anaesthesia the keys are
FLEXIBILITY and PREPAREDNESS as part of a holistic approach o Understand the type of LD you’re dealing with and the specific needs
of the child then adapt your practice E.g. warn the autistic child before touching them
o Discuss child’s needs with parents beforehand to facilitate planning o Be aware of communication difficulties
Use simple words Avoid metaphors Picture cards may be available to help explain the process
o Sedatives may be necessary o Good analgesia and anti-emesis are essential o Aim to minimise disruption to their usual routine
!20!
What if you have concerns about child safety? • Safety of the child is paramount and overrides all other duties • Features that may cause concern/suspicion of child abuse
o Unusual / excessive bruising (especially in a non-ambulant child/baby) o Cigarette burns o Bite marks o Unusual injuries in inaccessible places e.g. neck, ear, hands, feet,
buttocks o Intra-oral trauma o Genital / Anal trauma (with no clear history offered at presentation) o Trauma with inadequate history
• Paediatricians should perform examinations, when physical abuse is suspected. • Any concerns must be discussed with key child protection workers early • Each trust typically has named doctors / nurses (everyone should know how to
contact them) • Further management needs to be agreed with paediatrician, surgeon and
anaesthetist but led by the paediatrician • Full documentation should be contemporaneous, written and signed by
consultant • Duties of the Anaesthetist – from Child Protection and the Anaesthetist
document – March 2007 (intercollegiate document – RCoA, APA and RCoP) o Act in best interests of the child o Be aware of child’s right to be protected o Respect the rights of the child to confidentiality o Contact paediatrician with experience of child protection for advice
(there is usually a paediatrician on-call for CP, or designated doctor/nurse)
o Be aware of local child protection mechanisms o Be aware of the rights of those with parental responsibility
! 21!
!22!
Pre-medication • Generally you will prescribe premed analgesics, but sedatives, antacids and
antisialogogues may also be useful – but tend to be prescribed by consultants Analgesics
• Typically Paracetamol (20mg/kg) or Ibuprofen (5mg/kg) • Topical Cutaneous Anaesthetics
o The important thing is timing o Both are applied directly to unbroken skin and covered with an
occlusive dressing. o EMLA (Eutetic Mixture of Local Anaesthetic)
= 2.5% Lidocaine + 2.5% Prilocaine For use over 1 year of age Onset = 60-120mins Duration of action = 30-60mins
o Ametop = 4% Tetracaine gel (previously known as Amethocaine) For use over 1 month of age Onset = 40mins Duration = up to 4hours
Sedatives
• Used to reduce distress for particularly anxious or uncooperative patients. • Timing of administration is important • Midazolam
o PO / IV / Intranasal – bitter taste is best disguised with squash or mixed with Calpol / Ibuprofen
o 0.5mg/kg up to 20mg maximum o Onset = 20-30mins Duration = 45-60mins o Some children may become boisterous rather than sedated
• Clonidine o Can be used as both an analgesic and as a sedative o Typical dose is 2mcg/kg Maximum of 4mcg/kg o Requires up to 1hour for effect
• Alternatives o Ketamine
Often used with Midazolam (reduces incidence of dysphoria / hallucinations when used alone)
Often used if severe behavioural difficulties e.g. Autism PO 3-6mg/kg Onset = 30-60mins Can prolong recovery time
Antisialologues
• Used as a) a way of drying out excessive secretions or b) vagolytics to prevent potential bradycardia at laryngoscopy or during eye surgery
• Atropine = 20mcg/kg PO 90mins before induction • Glycopyrrolate = 10mcg/kg PO 60mins before induction • THESE ARE NOT THE SAME AS EMERGENCY DOSAGES
Antacids
• Given if child is at risk of regurgitation or reflux – especially ex-prem babies • Ranitidine 2mg/kg given 2hours before induction
! 23!
The ill child at Pre-Assessment • In general any active illness or infection may lead to the cancellation of an
elective procedure • However, a significant grey area exists with the so-called ‘cold’ or URTI • Respiratory complications during anaesthesia are up to 10times more likely
if a child has a respiratory tract infection, and can include: - o Coughing o Hypoxia o Laryngospasm o Dysrrhythmias o Even myocarditis if viraemic
• When to consider cancellation (postpone for 4-6weeks) o Fever >38C o Productive cough or purulent nasal discharge o Chest signs o Systemically unwell o Age <1year o Asthma
• If you are considering cancellation you MUST discuss with the consultant beforehand
• Factors to consider o Urgency of surgery o Type of surgery o Duration of surgery
• The decision to cancel is a joint one, made with our surgical colleagues.
!24!
The Anaesthetic Room and Induction • The anaesthetic room is where a child (and often the parents’) anxiety is at its
peak. • It is of vital importance to try and make the experience as positive for the child
as possible. • Any trauma inflicted in the anaesthetic room will reinforce already existing
fears and make future anaesthetics more difficult Restraining Children for Anaesthesia
• Various subtle definitions o Overpowering = use of physical restraint o Immobilizing = holding still o Containing = preventing escape / self-harm
• Restraint should be used as a last resort • An agreement should be made with the parents/guardians before hand about
the methods to be used • Ensure parental presence and involvement • Only minimal force should be used – in an age-appropriate manner 0 e.g.
wrapping or splinting • Take into account legal implications • Ensure sufficient staff are available • Have a debriefing session with the child +/- staff and parent asap after the
event Patient Positioning
• Neonates and children up to 6months are usually anaesthetised on the bed with ambient heaters, etc – WITHOUT parents.
• Infants may sit on parents lat • Older children may lie on the bed • The below diagrams show the ideal positioning in a parents lap for a) attempt
at cannulation and b) inhalation induction
! 25!
Distraction • In general an IV induction is the first-line choice for general anaesthesia. • Understandably children do not like the idea of cannulation and distraction
methods are useful to increase the likelihood of co-operation and subsequent success
• Simple things like talking to the child about something that interests them or listening to music or playing games can really help.
• The table below shows what is normal behaviour at various ages and some of the methods that can be used to play with / distraction children
Distraction Top Tips by Age
Infant (Birth – 1year)
Toddler (1-3 years)
Pre-School (3-5 years)
School Age (6-11 years)
Adolescent (12 years +)
• May fear separation from parent • Playing peek-
a-boo • Rattles and
dummies
• Being held by parent
• Blowing bubbles
• Very active and very independent
• Blurred distinction between fact and fantasy
• Talk about pets or favourite things
• Music and Television programmes
• Begin to be able to reason and compete with peers
• Talk about their interests
• Handheld videos and games
• Begin to seek peer acceptance
• Have body image issues and fear loss of control
• Talk about their interests
• Squeezing stress toys
• Handheld videos and games
Cannulation
• Can be difficult even for the experienced anaesthetist • Avoid repeated attempts, which will upset the child – always have a plan B. • The dorsum of the hand is the commonest site. • Others = wrist, dorsum of the foot, saphenous and the scalp in babies. • Use an appropriately sized cannula – typically 22G or smaller. • Tips
o In younger children with chubby hands, hold their whole hand and stretch the skin back – identifying a vein may by feel rather than sight.
o Try not to repeatedly tap veins, the whole process alerts the child to what is happening when you want there attentions focused elsewhere
o If you must, try squeezing the whole hand intermittently o Once cannulation is complete, you must hold on to the arm and keep it
still, until the cannula is securely dressed.
!26!
Intra-Osseous Access • Should always be considered as an option for vascular access in emergencies • APLS guidelines suggest that the IO access should be considered / obtained
after 2 failed attempts at cannulation in an emergency scenario • Sites
o Varies depending on clinical situation and age of child o Generally the proximal Tibia is the site of choice
2-3cm below the tibal tuberosity Care must be taken to avoid growth plates or joint spaces
o Other sites include the distal femur (3cm above lateral condyle), iliac crests, humerus etc
• Technique o An explanation for parents/child is essential o An appropriately sized intraosseous needle is selected o Loaded on EZ-IO drill o The insertion site is cleaned, local anaesthetic applied and stabilised o The drill is held at 90degrees to injection site o The drill is activated and advanced until bone is felt then stopped o Check the depth to see that the 5mm mark on the needle is visible o If so then the drill is advanced – with an associated decrease in
resistance If not, then the needle is withdrawn and replaced with a longer
one o Once the needle is advanced to the hub the drill is removed o The needle stylet is removed and a syringe is used to withdraw a small
amount of marrow and blood to confirm placement o IV extension set is attached –fluids/drugs given under pressure
• Complications of Insertion o Extravasation of drugs / fluids into soft tissues compartment
syndrome o Fractures o Osteomyelitis o Fat embolus
• Use o Almost everything can be administered via an IO needle, including
blood, but will need to be bolused / flushed through (i.e. drips will not run under gravity)
o Bolusing via an IO needle may be painful if the child is fully conscious • Removing the cannula
o Removed by pulling and rotating simultaneously – a luer-lock syringe can make this easier
o A sterile dressing is then applied Monitoring
• The minimum monitoring during induction is pulse oximetry – placed once child has lost awareness
• Proceeding to full AAGBI monitoring as soon as possible.
! 27!
Inhalational Induction • Probably the most important technique you will learn • Indications
o Potentially difficult airways – where distress may cause acute airway loss e.g. epiglottitis
o Patient or parental request o If venous access is likely to be difficult.
Two basic types
• Cooperative induction
o Begin by showing the child the mask before hand o Try to make the experience into a game – show them the bag and
encourage them to try and suck all of the air out and then blow it up o Start with 50:50 of Oxygen and Nitrous Oxide (e.g. 4L max. of each) o Two options for gassing
A) Hold mask on face with one hand and support the occiput with the other or
B) Hold the breathing system minus the mask between your thumb and forefinger, and cup your hand around the child’s mouth – this may make it easier to follow a child’s head if they start to move around.
o Slowly introduce Sevoflurane over the next 20-30 seconds increasing from 2% 4% 8%
o Maintain mask seal and support head until child looses consciousness o In a coordinated effort with parent and assistant, lift child onto the bed
and begin to support the airway o If using a Mapleson F – consider adding in an Exeter valve in order to
minimise anaesthetic room pollution o A good sign that the child is deep enough is the associated reduction in
heart rate o Once deep enough – reduce inspired % and flow rates to appropriate
level
!28!
• Uncooperative Induction o Always explain the process to the parents o Consider if the child is young (<3years) and unlikely to cooperate. o As above but start with Sevoflurane on 8% o If child is extremely uncooperative, consider abandoning procedure if
elective – as you will only traumatise the child further o Consider postponing surgery and pre-medicating with a anxiolytic or
sedative agent before trying again o As with all other times during anaesthesia AVOID unnecessary
stimulation – if you stimulate a child when they are light you may cause laryngospasm, breath holding, etc
• REMEMBER o Inhalation induction may be INAPPROPRIATE if there is myocardial
depression, severe hypovolaemia or vasodilatation and may result in profound hypoperfusion or cardiac arrest
Intravenous Induction
• REMEMBER Propofol administration can be painful • Two options
o Giving a small IV bolus of lidocaine and waiting before giving Propofol o Or mix a small volume of lidocaine with propofol in the same syringe.
• In young children, unlike adults, there is no window of opportunity to quickly insert an LMA after giving Propofol – this is because it redistributes too quickly.
• WAIT until deep enough on an inhalational agent before attempting insertion
! 29!
Airway Manoeuvres and Equipment • Most children’s airways should be relatively easy to manage. • However, if difficulty is encountered, don’t hesitate to switch to a two-handed
technique or seek help • Infant’s heads should be kept in a neutral position, which is often easiest by
removing any pillows – which flex the neck too much. o However, a shoulder roll may be required to get a neutral position –
because of the large occiput. • In older children the ‘sniffing the morning air’ position is desired.
• Be careful when holding a facemask – • • • • • • • • • • •
•
• Keep fingers on the mandible – compressing the soft tissues under the jaw can cause airway obstruction
• The ideal airway manoeuvre is a combination of jaw thrust and chin lift, keeping the mouth open
• Ventilation with the reservoir bag – should be of an appropriate tidal volume and rate (think, what should be normal for this age?)
• Be careful not to inflate the stomach – this is very easy is smaller children
!30!
Oropharyngeal (Guedel) Airways • In children < 8years insert concave side down – to avoid damaging the palate • In children >8 years insert concave side up (as in adults) • Sized by the distance between the angle of the jaw to the incisors • The below is a rough guide.
Age Colour
Neonate Pink or Blue Infant White Child Yellow Child / Small Adult Yellow or Green Laryngeal Mask Airways (LMAs)
• Size is determined by the weight of the patient • Pharyngeal reflexes must be sufficiently depressed before insertion – hence
wait until the patient is deep on inhalation agents before insertion (do NOT insert immediately after IV induction as you can cause laryngospasm, etc)
LMA Size Type of Patient Max. Inflation Vol. (ml) 1 < 5kg 4ml
1.5 5-10kg 7ml 2 10 – 20kg 10ml
2.5 20-30kg 14ml 3 30kg to small adult 20ml 4 Average adult 30ml 5 Large adult 40ml
iGels
• Reinforced LMAs such as iGels are also available in paediatric sizes
iGel Size Patient Size 1 2-5kg 1.5 5-12kg 2 10-25kg 2.5 25-35kg 3 30-60kg 4 50-90kg 5 >90kg
! 31!
Endotracheal Tubes • Tubes may be cuffed or uncuffed • Changes in technology & design have led to a preference for cuffed tubes
Uncuffed
• Choosing to use an uncuffed tube depends on the anaesthetist and the operation.
• Allows internal tube diameter to be maximised reduces air resistance • Aim to allow a small audible leak to minimise risk of tracheal mucosal damage • Disadvantages
o Aspiration is still possible o Pollution (I.e. anaesthetic vapours escape via leak) o Control of the leak may be difficult if high pressures are required (a
throat pack may help in this instance) • Tube Size
o Weight <2kg = 2.5mm Weight 2-4kg = 3.0mm o Neonate = 3.5mm 3months-1year = 4.0mm
• Over 2 years = (Age/4) + 4 Cuffed
• Generally used when there is: a shared airway, soiled airway, difficult ventilation and critical care cases.
• Reduces the risk of aspiration • Tube size = (Age/4) + 3.5
o I.e. cuffed tubes should be half a size smaller than uncuffed tubes for the same age child
• Cuff pressure must NOT exceed 20cmH2O Tube Length
• As we know ETTs are purposely made longer than necessary • The paediatric airway has two important differences that are important here: -
o The trachea is shorter than in the adult o The bronchi divide off the carina at the same angle
• These mean that: - o Endobronchial intubation is more likely and equally likely on both sides o Hence the need to auscultate to confirm position
• Formula o Length (cm) for oral tubes = (Age/2) + 12 o Length (cm) for nasal tubes = (Age/2) + 15
• Tips o ETTs should be inserted so that the black mark on the tube is just
beyond the cords at laryngoscopy
Airtraqs • Paediatric airtraqs are also available for both oral and nasal intubation • Oral intubation
o Infant = Size 0 = Grey = tube sizes 2.5-3.5 cuffed or uncuffed o Paediatric = Size 1 = Purple = tube sizes 4.0-5.5
Both require a minimum mouth opening of 12.5mm o Small adult = size 2 = Green = tube sizes 6.0-7.5 o Minimum mouth opening of 16mm
!32!
Laryngoscopy • There are two laryngoscope blades which are typically used
o Straight blades (there are several different types e.g. Miller) Used to lift the epiglottis out of the way
o Curved (Macintosh) blade Inserted into the vallecula
• Firstly, you should use the blade you have most experience with. • As a rule of thumb: -
o Use a straight blade in children under 1year of age o Use a curved blade in children over 1year of age
• The keys to laryngoscopy in paediatrics are to: - o A) Only attempt it when the child is sufficiently, deeply anaesthetised
and o B) Be gentle, to try and limit airway trauma
• Laryngoscopy is vagally stimulating and can cause two major problems o Laryngospasm o Bradycardia
• REMEMBER to beware of wobbly teeth!!!
!33!
!34!
!35!
!36!
What are the three common peri-operative critical events in children? • Desaturation – due to a combination of increased work of breathing, small FRC
(low intrapulmonary O2 reserve), higher basal metabolic rate and diaphragm dependence. Other causes include: - endobronchial intubation, reduced diaphragmatic compliance from stomach inflation, etc
• Laryngospasm – due to high parasympathetic tone, most likely during light anaesthesia or vagally stimulating procedures e.g. laryngoscopy or extubation
• Bradycardia – due to high parasympathetic tone, most likely during vagally stimulating procedures e.g. laryngoscopy, extubation and squint surgery
Peri-operative Fluids & Glucose
• Whilst the following formulae are useful guides, remember that therapy should always be guided by the dynamic clinical situation.
• Hypotonic solutions should be avoided because of the risk of hyponatraemia post-op (secondary to post-op ADH release and water retention)
Fluid Deficit
• Use an Isotonic fluid e.g. 0.9%NaCl or Hartmann’s Solution • Bolus for Hypovolaemia = 20ml/kg (or 10ml/kg if trauma or cardiac concerns) • Nil by Mouth Deficit = Hourly requirement x number of hours NBM • Dehydration
o Dehydration without shock = <10% fluid loss (replace slowly) o Dehydration with shock = >10% fluid loss (replace quickly) o Replacement fluid (ml) = % dehydrated x weight (kg) x 10
Fluid Maintenance
• Use an Isotonic fluid e.g. 0.9%NaCl or Hartmann’s Solution • Normal Hourly Maintenance Requirement
o 4ml/kg for first 10 kg o 2ml/kg for second 10kg o 1ml/kg for every additional kg
I.e. a 22kg child will require 62ml/hr (40ml for 1st 10kg, 20ml for 2nd 10kg and 2ml for the remaining 2kg)
• Normal Daily Maintenance Requirement o 100ml/kg for first 10kg o 50ml/kg for second 10kg o 20ml/kg for every additional kg
Fluid Loss Replacement
• Use an Isotonic fluid e.g. 0.9%NaCl, Hartmann’s Solution or a colloid +/- KCL o Or blood if required – depending on haematocrit
• Losses should be measured, wherever possible, and replaced 2-4hourly Glucose
• As we know, premature babies and neonates have an increased glucose requirement. Other scenarios in which glucose may be monitored or needed include: - low body weight and prolonged surgery
• A generally accepted treatment limit for hypoglycaemia is <2.5mmol/L • Hypoglycaemia Treatment
o Bolus of 2ml/kg of 10% Dextrose o Infusion of 10% Dextrose at 4-6ml/kg/hour
• It is important to monitor for hyperglycaemia as well, since this can cause a hyperosmolar state leading to diuresis and intraventricular haemorrhage
! 37!
Positioning • This is largely dictated by the type of surgery, but it remains important to
check pressure areas and ensure easy access to cannulae. • In the supine position, a position with the arm in an oath-swearing or Native
American ‘How’ greeting is safe and easy. Extubation and Emergence
• Laryngeal reflexes are more pronounced in younger children • Maintain anaesthesia until the child has been transferred back to their bed • It is wise to recover most patients in the left lateral position with a slight head-
down tilt – unless contraindicated by surgery • Avoid unnecessary stimulation as it can result in laryngospasm, etc • What happens next depends on what type of airway has been used
LMAs
• These can either be removed in theatre or left in-situ whilst the child is transferred to recovery with child in the lateral position
• The decision depends on several factors: - o Local policy o Perceived difficult of managing the airway o Type of surgery e.g. ENT- possible cord irritation from blood/secretion o Use of peri-operative opioids (that may suppress laryngeal reflexes)
ETTs
• The aim is to AVOID laryngospasm or other critical events • Maintain anaesthesia until return of neuromuscular function • Put patient into the left lateral position with slight head down tilt (unless
contraindicated by surgery) • Avoid unnecessary stimulation • Two options – extubate awake or deep (awake is preferred for novices)
Recovery
• Children usually recovery quickly and can be discharged rapidly • Discharge criteria include: -
o Restoration of consciousness and appropriate activity for patients age o Stable vital signs o Adequate control of nausea and vomiting and pain o No surgical or anaesthetic complications o Handover of patient information, including details of surgery, possible
post-op events and instructions o Advice for parents for after discharge including follow-up
!38!
Paediatric Breathing Systems • Determined by
o Childs age and weight o Spontaneous or controlled ventilation
Children <20kg Mapleson F
• Most common • A.k.a. Jackson-Rees modification to the Ayre’s T-piece
o A Mapleson E system with a 500ml open-ended reservoir bag
• A Low resistance and low dead space system • Used for spontaneous, assisted and controlled ventilation in all ages
o Less efficient if >20kg • Can provide PEEP/CPAP by partially occluding end of the bag
o The bag should be held as shown in the below diagram, with the open tail between the ring/little finger and the palm – allowing the thumb and forefingers to squeeze the bag
o This allows PEEP/CPAP to be applied whilst ventilating – it is a technique that takes time to master
• FGF to prevent rebreathing is high o SV = Minimum is 4l/min – up to 3 times MV o Controlled – FGF = 1000ml + (200ml/Kg)
• Difficult scavenging o Can be countered by the addition of an Exeter PTS Valve (shown
below)
! 39!
Children >20kg Mapleson D (including Bain)
• Used for controlled ventilation in older (>20kg) children • Less efficient for spontaneous ventilation • Valve is at proximal end and FGF is always delivered at patient end –
especially useful if access is limited (length of 540cm can be used in MRI scanners)
• FGF o SV = 150-250ml/kg/min o Controlled = 70-100ml/kg
Circle Systems
• Narrow 15mm tubing – reduces compression volume • Smaller distal connections minimize dead space • Ventilator is capable of ventilating small children • Vapouriser is out of circuit • Advantages
o Low FGF o Economic – less volatile used o Easy scavenging reduced pollution o Conservation of heat and water vapour
• Disadvantages o Unidirectional valves resistance (also valves can stick)
• FGF – initially high (several L/min) for 5-10mins to wash Nitrogen from circle and patients lungs. Later reduced to 0.5-1L/min – although this depends on the degree of leak around the cuff.
!40!
Paediatric Regional Anaesthesia The maximum dose of Bupivicaine is 2ml/kg Caudal Epidural
• Indications: - Lower abdominal, pelvic, perineal, penile and lower limb surgery • Block Sensory > motor > autonomic • Identify the sacrococcygeal membrane – apex of equilateral triangle, base of
which is formed by the two posterior superior iliac spines • Using a cannula aim cephalad at an angle of 45degrees until a ‘give’ is felt • Flatten / straighten out trajectory and advance cannula no more than 2cm • Dose - Infants = 0.5-1.25ml/kg of 0.25% or less • Additives to extend block
o Clonidine = 1mcg/kg o Diamorphine = 30mcg/kg o Ketamine = 0.5mg/kg of preservative free o Morphine = 50mcg/kg of preservative free
Epidural opioids are only with appropriate post-op monitoring • Complications (rare)
o Motor block, Urinary retention, Hypotension, Infection o Inadvertent dural puncture / intravascular injection
Regional Nerve Blocks
o Use 21G or 23G needles o Ultrasound (USS) guidance is increasingly being used for regional blocks
Ilioinguinal / Iliohypogastric blocks
o Useful alternative to caudal for herniotomy, hydrocele, orchidopexy o USS target = fascial plane between internal oblique & transversus abdominus o Landmark Technique
o Injection site1cm medial to Anterior Superior Iliac Spine o ‘Pop’ if felt passing through external oblique aponeurosis inject
approximately half LA o Advance needle - 2nd ‘pop’ felt going though internal oblique
aponeurosis inject approximately half LA o Retain some LA for subcut infiltration in a fan from injection point for
inter/sub-costal nerves o Dose – 0.75ml/kg 0.25% Bupivicaine o 10% incidence of femoral nerve blocks
Penile Block (dorsal nerve of penis)
o Safe, simple and predictable but does not always block ventral penis o Dose - 2-6ml of 0.25% Bupivicaine
o Solutions containing Adrenaline are ABSOLUTELY CONTRAINDICATED o Landmark Technique
o Locate inferior border of pubic symphysis at dorsal base of penis o In midline insert needle, angling 5degrees laterally o ‘Pop’ is felt passing through Buck’s fascia aspirate& inject o Withdraw needle and redirect 5degrees laterally on opposite side
aspirate & inject on other side of suspensory ligament o Retain some LA for subcut infiltration around ventral base of penis
Spinals and Epidurals
o More difficult in children due to less well-developed ligamentum flavum and smaller distances between structures, hence requires experienced hands
! 41!
Paediatric Pharmacology • Larger volume of distribution for water-soluble drugs (higher proportion of
body weight is water – prems = 90%, neonates = 80%) • Lower total plasma protein concentration (especially alpha1-acidglycoprotein) • Neonates have little fat or muscle tissue • Immature hepatic and renal function leading to prolonged elimination
(especially in neonates) Pharmacokinetics
• Most drugs are metabolised and eliminated slowly o Tend to accumulate with repeated doses
• Reduced clearance Absorption
• Inhalational and IV drugs are absorbed normally • IM / SC depots are slowly absorbed in neonates
Distribution
• High cardiac output rapid distribution • Protein binding is reduced in neonates and young infants increased free
concentrations • Increased volume of distribution of highly ionized drugs (e.g. neuromuscular
blockers) due to increased body water and extracellular fluid volume • Less developed BBB greater uptake of partially ionized drugs e.g.
morphine Metabolism
• Higher basal metabolic rate • Immature liver function less 1st pass effect • Older infants and children show rapid elimination • Hofmann degradation is age-independent
Excretion
• Mostly via kidneys • GFR relative to surface area is reduced – but increase to adult levels within 1st
year • Proximal tubule secretion reaches adult level by 6months
!42!
Drugs used in Paediatrics Intravenous Anaesthetic Agents Propofol
o For induction, sedation and TIVA (in the short-term). o ‘Contraindicated’ for long-term infusion in ICU due to so-called Propofol
Infusion Syndrome (metabolic acidosis, rhabdomyolysis and cardiac failure / arrest) – seen in children sedated on ICU
o Propofol Induction Dose = 2-4mg/kg o Propfol TIVA
o TCI is NOT validated in small children – as it is based on adult nomograms and data is extrapolated.
o It may be appropriate for older children to use TCI. o Otherwise infusion dose / rate should be worked out on rate (i.e.
ml/kg) Others
• Thiopentone o Neonates = 2-4mg/kg o Children = 5-6mg/kg
• Ketamine o IV = 1-2mg/kg
Duration = 5-10mins o IM = 5-10mg/kg
Onset 3-5mins Duration = 15-30mins
Volatile Anaesthetic Agents
• All cause some cardiovascular depression and bronchial smooth muscle relaxation
• MAC values vary with age – as outlined below
• Sevoflurane o Commonest agent used for inhalation induction o High concentrations apnoea o After maintenance some children can become delirious o Less irritant means it can be used at 8% concentration from the start
• Isoflurane o Commonest maintenance agent
MAC Age Sevoflurane Isoflurane Neonate 3.3 1.6 Infant 3.2 1.9 Child 2.5 1.6
! 43!
Muscle Relaxants and Reversal • Suxamethonium = 2mg/kg (3mg/kg in neonates)
o Onset 60seconds o Duration 4-6mins o Used mostly as part of a RSI o Fasciculation may not be seen in small children
• Atracurium = 0.5mg/kg • Rocuronium = 0.6mg/kg • Neostigmine = 50mcg/kg – dilute 1amp of reversal (2.5mg neostigmine +
500mcg Glycopyrrolate) in 5mls and give 0.1ml/kg (1ml/10kg) Opioids and Naloxone
o Fentanyl = 2-4mcg/kg – typically 1mcg/kg on induction o Morphine = 0.1mg/kg o Remifentanyl
o As a bolus to facilitate intubation = 0.1-1mcg/kg Bradycardia and muscular rigidity can occur
o As an infusion = 0.25-0.5mcg/kg/min o Naloxone = 4mcg/kg
Other Analgesics
• Paracetamol o Maximum 24 hour dosage (in divided doses)
Neonates = 30mg/kg Infants – 6years = 60mg/kg Children 6 -18years = 90mg/kg
o PO Neonates = 15mg/kg 1month – 12years = 20-30mg/kg as a single dose then 15-
20mg/kg every 4-6hours 12-18years = 1g every 4-6hours (maximum 4doses in 24hours)
o IV Weight <10kg= 7.5mg/kg every 4-6hours (Max30mg/kg) Weight10-50kg=15mg/kg every 4-6hours (Max 60mg/kg) Weight >50kg = 1g every 4-6hours (Max 4g)
o PR Neonates = 30mg/kg loading dose 15-20mg/kg 4-6hourly Beyond Neonates = 30-40mg/kg loading dose 15-
20mg/kg 4-6hourly • NSAIDs should only be used in children over 3months of age • Ibuprofen
o Not to be used in children under 3months or under 5kg o Older Children = 5mg/kg 6hourly
• Diclofenac o PO = 1mg/kg 8hourly o IV = 1mg/kg o PR = 1-2mg/kg o Maximum by all routes = 3mg/kg/day
!44!
A note on Codeine • There have be recent concerns from the MHRA regarding the use of Codeine in
paediatric populations • There appears to be a variation in Codeine metabolism in various genetic
groups – so-called ‘fast metabolisers’ metabolise Codeine to Morphine at a faster rate which may lead to accumulation and side effects
o Fast Metabolisers are commoner in patients of Middle Eastern and African/Ethiopian descent (incidence 30% versus 0.7% in Caucasians)
• Adverse events have been reported in children with OSA undergoing adeno-/ tonsil-ectomies
• The APA position: - o Codeine is still a viable weak opioid for the treatment of moderate
pain o Recommended dose is 0.5-1mg/kg four to six hourly
• The use of Codeine in paediatrics may vary between hospitals, but many centres have stopped using it in tonsillectomies for OSA (because of potential dangers)
Emergency Drugs
• Atropine = 20mcg/kg • Glycopyrrolate = 10mcg/kg • Adrenaline = 10mcg/kg = 0.1ml/kg of 1:10,000 or 0.01ml/kg of 1:1000
Post-Operative Nausea and Vomiting
• PONV is approximately twice as frequent in children as in adults • It can result in a number of complications including wound dehiscence,
electrolyte imbalance and pulmonary aspiration. • Risk Factors
o Patient factors Increased risk from age 3 until adolescence History of PONV and/or motion sickness Increased incidence in post-pubertal girls
o Surgical factors Strabismus surgery Tonsillectomy +/- Adenoidectomy Surgical procedures >30mins duration
o Anaesthetic factors Use of Volatile Anaesthetics Use of Opioids Use of Anticholinesterase N2O is NOT associated with high risk of POV
• APA Recommended Treatments (2009 – Guidelines on the Prevention of Post-operative Vomiting in Children)
o If at risk give IV Ondansetron 0.15mg/kg prophylactically o Consider IV anaesthesia and opioid alternatives if at high risk o If already had Ondansetron, give a 2nd anti-emetic from another class
e.g. IV Dexamethasone 0.15mg/kg slowly Anti-Emetics
• Cyclizine = 1mg/kg • Ondansetron = 0.15mg/kg • Dexamethasone = 0.15mcg/kg
!45!
!46!
! 47!
!48!
!49!
!50!
!51!
!52!
!53!
!54!
!55!
!56!
!57!
Commonly Used Drugs in Paediatric Anaesthesia