Department of Anaesthesia University of Cape Town

Paediatric Anaesthesia

Introduction

Children, especially those under the age of 8 years, are not small adults. When children present for surgery, there are many factors that are important to consider. The effects of hospitalisation and medical interventions may have profound emotional consequences for children. Some show behavioural disturbances that persist long after the event. The age of the child, the emotional maturity, cultural background and parental influence will each contribute to this. Infants under six months of age have minimal separation anxiety and will readily accept another person in place of their mother. Older infants and young children are much more affected, and separation from parents, home, siblings, and their favourite toy or blanket is frightening; and psychosocial issues may become problematic. With children up to 4 - 5 years of age, considerable regression may occur because one is unable to reason with, or explain to them, what is happening. Once they reach school-going age, their fears are different; pain, what effect surgery will have on their looks, and the loss of control over what is happening to them.

One symptom all children fear is pain, although this may have different meanings for different individuals at different ages. The environment for children needs to be child-friendly and appropriate for the different ages of patients who will be treated at that particular unit. Staff caring for ill children and their parents should be adequately trained to do so.

Paediatric anaesthesia requires meticulous attention to detail for every aspect of care.

Definition of age groups

Prematurity: Less than 37 weeks gestational age Neonate: 0 - 28 days (first 28 days of life for a full term baby) Infants: 1 month - 1 year Toddlers: 1 - 3 years Children: 3 - 7 years Older children: 7 - 12 years Adolescents: 13 - 18 years

These subsets have different anatomic, physiological and pharmacological parameters. A specific approach is needed for each group. The most marked differences are in the youngest age groups less than 3 years.

Anatomy & physiology: Differences between adults & children

Cardiovascular system (CVS)

The neonate has a poorly developed and non-compliant myocardium The stroke volume (SV) is fixed and therefore cardiac output (CO) is heart-rate (HR) dependent

CO = SV x HR Sympathetic innervation is limited at birth and vagal tone predominates; this may result in

significant bradycardia during stressful situations, e.g. hypoxia, hypovolaemia, acidosis, large anaesthetic doses and vagal stimulation

Immature baroreceptors also limit a compensatory increase in HR when hypovolaemia is present

Always consider the possibility of anatomical defects, especially in premature babies – A patent ductus arteriosum (PDA) is common

Respiratory system

Anatomic differences are important: Neonates have a large floppy head, tongue and epiglottis; the narrowest part of the airway is sub-glottic at the cricoid ring (diameter of 3 - 4 mm!); this is different from adults where the narrowest part is at the vocal cords

Neonates and infants up to 6 months are obligate nasal breathers Lung volumes, e.g. tidal volume (VT), are much smaller: VT is 6 - 8 ml kg-1

The VT of a 4 kg neonate will be 24 - 32 ml vs. an adult VT of 500 ml!

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Respiratory rate (RR): 30 - 40 breaths min-1 O2 consumption: 6 - 9 ml kg-1 min-1 vs. adults 3 - 4 ml kg-1 min-1. Hence prone to desaturation Reduced functional residual capacity (FRC) with decreased oxygen (O2) reserve Alveoli are immature with resultant decreased lung compliance Chest wall is compliant and they respond to respiratory compromise and distress with tracheal

tug and intercostal recession Neonates rely on good diaphragmatic function to allow decent respiratory excursion and any

increased intra-abdominal pressure from space-occupying lesions may hinder breathing The control of breathing in full-term neonates is usually not a problem; however premature

neonates are prone to apnoea. Anaesthesia in the premature increases the risk of apnoeas postoperatively

Haematology

Blood volume: 90 - 100 ml kg-1 in the neonate and drops to normal adult value of 80 ml kg-1 by 1 year

Haemoglobin (Hb): 18 - 20 g dl-1 at birth and 75 - 80 % is foetal Hb (Hb F) Hb F is gradually replaced by adult Hb A A physiological anaemia is present at 2 - 3 months because erythropoietin stops being produced

temporarily at birth and the Hb drops to 10 g dl-1; at 1 year Hb reaches normal levels Hb F has a high affinity for O2 and offloads it poorly to the tissues, i.e. a left-shifted O2

- Hb disassociation curve

Coagulation in neonates is limited as the liver is immature and the vitamin K dependent clotting factors (II, VII, IX and X) are at low levels – Newborns are routinely given a vitamin K injection

Liver and renal

Both liver and renal function is immature at birth Metabolism and excretion of anaesthetic drugs are reduced Neonates have a tendency to hypoglycaemia due to low glycogen stores

Central nervous system (CNS)

Although the CNS is not fully developed at birth, neonates can see, smell, hear and feel pain! Drug requirements for IV agents, opioids and muscle relaxants vary according to the age of the

patient but neonatal minimum alveolar concentration (MAC) is the same as, if not lower than, adults; whilst the MAC for infants and children is higher than adult MAC

The fontanelles are open for the first couple of months and therefore the cranium is not a rigid box as in adults and can better accommodate increases in intracranial pressure

Thermoregulation

Hypothermia is a serious problem, especially in neonates. They have greater heat loss through a relatively large head and large organs close to the skin surface, e.g. liver; and their heat production is reduced due to an inability to shiver, or move in response to cold. Their only mechanism of heat production is brown fat thermogenesis Be aware of this risk in theatre and take steps to keep baby warm

Pre-operative assessment

The pre-operative assessment of children is different from adults and different for each age group. A complete medical and surgical history is vital. Other concerns include a family history, allergies, any medications the child is taking and the time of the last meal. In infants and toddlers, an obstetric and birth / perinatal history is imperative to identify early problems and ex-premature babies. Immunisation and growth charts are important in children – Ask to see their “Road-to-Health” cards.

Always exclude any congenital abnormalities and syndromes, as these children can have complicated defects that lead to a multitude of anaesthetic problems.

Identify those children who have had a recent upper respiratory tract infection (URTI) as they may have intra-operative respiratory problems, e.g. increased secretions, breath-holding, laryngospasm or bronchospasm. If a child has an URTI it is best to postpone elective surgery for at least 2 weeks, and for a lower respiratory tract infection (LRTI) postpone for 4 weeks minimum.

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It is difficult to assess the airway in very small children and babies. The Mallampati score has not been validated in children. Try to look for good mouth opening and good movement of the neck. Look at the teeth; ask if any are loose and coming out currently! This is important to document, as there is a danger of knocking out loose teeth with airway manipulation and potential aspiration into the lungs – A serious complication!

The remainder of the pre-operative assessment involves a general examination plus relevant special investigations. Most healthy children undergoing minor surgery require no blood work except a finger-prick Hb.

The art of paediatric anaesthesia begins during the pre-operative interview! This interview involves the child and parents / caregiver. If the child is old enough to understand and communicate, you should explain the anaesthetic to them in age-appropriate terms. Make it fun, exciting and reduce possible anxiety. It is useful to show the child the mask and bag of the T-piece breathing system so that they know how the gas induction will proceed. A video of the “theatre experience” is also very educational. Communication with the child and parents about the anaesthetic, operation and post-operative pain management encourages discussion about fears they may have about the entire proceedings.

Verbal consent and documentation of this in the anaesthetic chart, for insertion of rectal suppositories is advised, although not legally required in South Africa. If regional anaesthetic techniques are to be used, explanations and consent should be obtained.

Premedication

No premedication is given to infants under 6 months to 1 year old (or < 6 kg), as they do not experience parental separation anxiety. Avoid sedative premedication in children with obstructive sleep apnoea (commonly with large tonsils and adenoids) or any other cause of potential airway obstruction.

Premedication may range from minimal ‘light’ sedation to ‘heavy’ sedation. Not all children require premedication. Simple re-assurance and the presence of a parent, plus the pre-operative visit are sufficient to allay anxiety. There should be no so-called “standard premed”; each child should be assessed individually and the premedication chosen to suit the child, the pathology and any associated disease. Options for oral premedication:

Midazolam (Dormicum®) 0,25 - 0,5 mg kg-1 (max 15 mg) PO half-hour pre-operatively. The dose is achieved by cutting a 15 mg tablet and crushing it. It tastes extremely bitter and must be given with something sweet, e.g. ½ Darrows dextrose fluid or 50 % dextrose. Short-acting.

or

Trimeprazine (Vallergan forte®) 2 - 3 mg kg-1 (max 90 mg) PO 2 hours pre-operatively. This is a potent, long-acting sedative, with antisialogogue and anti-emetic properties. Useful in burns children. Avoid if children are sensitive to tartrazine.

…

and, if needed add

Droperidol (Inapsin®) 0,1 - 0,2 mg kg-1 (max 5 mg) PO 2 hours pre-operatively. A good anti-emetic.

or

Ketamine (Ketalar®) 10 mg kg-1 PO 1 hour pre-operatively. This should only be administered in theatre as it is an anaesthetic induction dose, and the child should then be monitored prior to surgery.

Stopayne® syrup (5 ml contains 120 mg paracetamol, 5 mg codeine, 6,25 mg promethazine [a sedative], and 10 % alcohol) has excellent analgesic, sedative, anti-emetic and antipruritic properties. It is sometimes mixed with the premedication to alleviate the bitter taste of midazolam and ensures pre-emptive analgesia before the operation starts.

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Fasting rules

6 hours for food or formula milk (cows milk curdles in the stomach to form a solid) 4 hours for breast milk 2 hours for clear fluid (uncarbonated apple- / grape- juice, Oros® or ½ Darrows dextrose fluid)

We encourage children to take orally up to 2 hours pre-operatively to avoid long fasting periods. Ward staff or parents can administer 10 ml kg-1 of apple juice or ½ Darrows dextrose (a dextrose containing paediatric IV maintenance fluid). This avoids thirsty, irritable, hypoglycaemic children in theatre pre-operatively. It is good practice to do the youngest children first on the morning theatre slates.

The child after trauma should be regarded as having a full stomach prior to surgery as gastric emptying is delayed due to pain, anxiety and potential opiate use in trauma unit.

Preparation of theatre for paediatric surgery

In a paediatric hospital, the theatre suites are well stocked with a range of paediatric equipment. However at other hospitals, where paediatric cases are performed infrequently, it may be difficult to find all the equipment you will need for a paediatric case. Often the anaesthetic staff will have a specific paediatric trolley with a selection of the equipment listed below on it. It is important to be meticulous in your pre-operative preparation of theatre and ensure that you have everything you need and more. This is the practise of safe anaesthesia and entirely the anaesthetist’s responsibility.

a) Breathing circuits The Jackson-Rees modified Ayre’s T-piece is a lightweight circuit with no valves and an

open-ended reservoir bag. The O2 is delivered close to the child’s face and the reservoir bag can be used to assist ventilation manually as well as monitor spontaneous breathing. This T-piece can be used for children < 20 kg or 6 years. Fresh gas flow (FGF) is 2 - 3 x minute volume (MV) for spontaneous breathing. For example: A 10 kg child with VT of 80 ml (8 ml kg-1) and RR of 25 will have a MV of 2 l min-1 and thus FGF = 4 - 6 l min-1

Paediatric circle circuits (contain a soda-lime absorber together with inspiratory- and expiratory- valves that ensure unidirectional flow). The tubing has a reduced diameter and is lighter. There is a universal trend towards low-flow anaesthesia and circle absorber systems provide cost-effective anaesthesia with less pollution, but appropriate inhalational agent and gas monitoring must be available

Both breathing circuits should be attached to the anaesthetic machine and checked prior to anaesthesia as part of the full machine check

b) Paediatric ventilators

Must be able to deliver small volumes; preferably with volume- and pressure- controlled modes. We tend to use pressure controlled ventilation (PCV) in paediatrics, as it compensates for leaks

c) Facemasks Specially designed paediatric facemasks with a shallow body minimise equipment dead space.

Children have flatter faces and noses Facemasks should be transparent and often flavoured to make gas induction more acceptable A selection of facemask sizes must be available

d) Oropharyngeal airways (Guedel airways) Selection of sizes – Measure the size from the middle of the incisors to the angle of the jaw.

If the airway is too small it will not lift the tongue off the floor of the oropharynx and the airway will remain obstructed. Nasopharyngeal airways are available and better tolerated

e) Laryngeal mask airways (Brain airways) Sizes 1, 1½, 2, 2½ and even 3 will be appropriate for children Sizes 1 and 1½ are meant for infants up to 10 kg, however these are difficult to position properly

and easily displace resulting in laryngospasm and hypoxia; it is often safer to secure the airway with an ETT or hold the face mask for a short anaesthetic

f) Laryngoscopes Selection of sizes and blade types Types: Curved Macintosh or straight Seward / Miller / Wisconsin blades. (See appendix)

The straight blades are often easier to use for neonates

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g) Introducers and Magill forceps Paediatric-appropriate sizes

h) Endotracheal tubes (ETTs) and suction The tubes for children range from 2 - 6,5 mm internal diameter.

At term neonates will take a 3 - 3,5 mm tube Most ETTs are uncuffed to prevent post-intubation oedema. From size 5 mm upwards the tubes

come with cuffs if required. It is good practise to avoid cuffed tubes until the child is over 8 - 10 years old. A size 5,5 cuffed ETT is useful for the child over 6 when you are not sure which size to use, as a back-up. There is a trend towards using smaller cuffed tubes in smaller children

Choosing the appropriate size:

4 + age / 4 = tube diameter in mm

All children are different so have ETTs 0,5 mm size above and below readily available. Example: A 4 year-old needs a size 5 mm ETT (from the formula); plus a 4,5 mm and 5,5 mm as alternatives on the airway trolley

Correct tube placement is confirmed by easy passage into the larynx and the development of a leak at 10 - 20 hPa (cm“H20”). No leak indicates that the tube is too big, and should be replaced, as oedema can result in post-intubation stridor. Remember the narrowest part of the airway is below the cords at the cricoid ring

The formula to estimate ETT length at the teeth / gums:

12 + age / 2 = length in mm

This formula is once again a guideline and the tube length must be confirmed with equal air-entry on bilateral auscultation in the axillae. A useful guide to placement: Length of ETT distal to the cord (cm) = diameter of the tube (mm). Example: A 3 mm ETT should be 3 cm in at the cords

A paediatric Yankauer suction nozzle for mouth suctioning under direct vision must be available, as well as suction catheters of varying sizes to for airway suctioning of secretions via the ETT

i) Intravenous (IV) cannulas, central venous pressure (CVP) lines and arterial lines A range of sizes and safety cannulae should be available for the child Common sizes are 22 G (blue) and 24 G (yellow) cannulae for peripheral venous access

j) IV fluid and lines 200 ml bags of fluid are more appropriate than 1 litre bags The fluid giving set should be a 60-dropper, to limit the rate of administration A buretrol / paedatrol (volume control device) is important so that the fluid volume administered

can be controlled for all children < 10 kg For short-term IV access we often draw up flush lines with a 10 ml syringe of normal saline

Dead space of thin flush lines varies depending on make; usually 1,4 - 1,8 ml (check packing) An “elbow” or short extension set is used in tiny babies – Easier to secure with less dead space

Drugs are usually diluted with normal saline as opposed to water, as this is more physiological Ensure meticulous de-airing of all lines and intravenous tubing

k) Feeding tubes, nasogastric tubes (NGT), urinary catheters Use the smaller nostril for feeding or NGT and secure well; the larger nostril is for breathing!

l) Paediatric temperature probes Oral, nasopharyngeal, rectal (with covering glove) probes, or tympanic membrane thermometer

m) Warming equipment Forced air warmer: Convection warm air devices (Bair-Hugger®, WarmTouch®) Overhead radiant heaters Ability to increase theatre temperature Heated underblankets In-line fluid warmers Humidifiers and paediatric heat moisture exchange filters (HMEFs) Selection of hats, gamjees (cottonwool and gauze pads) and plastic sheets for insulation

n) Monitors Size-appropriate ECG stickers and leads, non-invasive BP cuffs, pulse oximeter probes

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Induction

Most children do not arrive in theatre with an IV line, and dread the prospect of being stuck with a needle. There are two options for induction, IV or inhalational:

Intravenous induction if an IV line is present, or when local anaesthetic cream (EMLA) has been placed on the hand or arm 1 hour pre-operatively to anaesthetise the skin and render IV cannulation painless. This technique is an art in distracting the child so they are unable to see the needle going in! Commonly used IV agents are propofol and ketamine

Inhalational induction where the potent and non-irritant volatile anaesthetic agents, sevoflurane or halothane, will render a child unconscious within minutes. Older children will often co-operate and breathe in and out ‘blowing up the balloon’ or pretending to be a ‘spaceman breathing special air’ until they drift off to sleep. A light premedicant does aid co-operation. The smaller child may resist a little more as they may not understand what is happening. Inhalational induction is commonly practised at childrens’ hospitals and the student should have the opportunity to observe and perform several inductions. This is also a good opportunity to witness the different stages of anaesthesia

Parental presence in theatre is helpful for co-operation of the child over 6 months. They fear separation from their parents or caregiver. Mom or dad (one parent) can hold the little one on their lap as they go off to sleep or stand alongside the theatre table holding their hand. Once the child is asleep the parents are often filled with emotion and need to be re-assured that their child will be well-cared for, they may want to give a little ‘good-luck’ kiss (don’t ask them to kiss their child goodbye as this has dreadful connotations), and they should be escorted back to the theatre door. As mentioned, children less than 6 months do not suffer from separation anxiety; thus it may be easier for parents and staff to take these infants into theatre without the parent

A choice of induction can be offered to older children who are not afraid of IV lines, or those who have had multiple procedures. They may have a preference for inhalation or IV induction depending on their particular fears or phobias of mask or needle

Muscle relaxation is not routinely required to intubate children and suxamethonium has many side effects that we would prefer to avoid in paediatrics; especially bradycardia and malignant hyperthermia (rare). Spraying the cords with 2 % lignocaine or an IV dose of propofol (1 - 2 mg kg-1) once an IV line is established, is helpful in abolishing airway reflexes prior to intubation. Non-depolarising muscle relaxants are given once the airway is secure, if required for the surgery

Maintenance

Maintenance of anaesthesia is a choice between an inhalational or intravenous method. Frequently in children, we choose the inhalational method. If sevoflurane has been used as the induction agent, change to isoflurane or halothane (but rapidly becoming obsolete) for maintenance as they are more cost-effective and may minimise the incidence of post-sevoflurane emergence delirium / agitation.

a) Doses of drugs: in mg kg-1 ! Children vary dramatically in size, from the 1 kg premature neonate to the 30 - 80 kg adolescent. Drug dosing must be adjusted accordingly. It is useful to have a calculator to work out the required mg kg-1 dose accurately. Drugs may need serial dilutions for very small babies.

A useful book to have is the Frank Shann Paediatric Drug Doses Book. It contains all drugs and doses, plus information on children’s weights, heights, size of ETT, LMA, IV lines, how to work out infusion schedules and much, much more! (Including some hidden recipes )

b) Monitoring The level of monitoring depends on the nature of the case. Routine monitoring in children is often no different from adults, however all the equipment is smaller.

Pulse oximeter probes are often the only monitor, if any, that can be placed before the induction proceeds because exposing the child and applying monitors may frighten and distress them. Probes are wrap-around or clip-on probes. It is advisable to place 2 probes with every anaesthetic as it is not unusual for one to be lost or unreliable during the procedure. ECG, non-invasive BP (NIBP) cuff of appropriate size, capnograph and temperature probes are routine. Anaesthetic agent monitoring is standard on the new machines and mandatory for low-flow anaesthesia. Nerve stimulators are under-utilised in paediatrics, and are particularly useful in assessing the child with postoperative apnoea, and excluding muscle paralysis as a cause. Invasive monitoring such as arterial lines and CVPs will be dictated by the surgery or patient.

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Anaesthesia in children requires attention to detail – Small ETTs can be displaced or kink in a matter of seconds, and lines and monitors can be removed accidentally. Securing the airway equipment, monitoring and IV access and your access to these is imperative before the patient is cleaned and draped. A surgical screen is invaluable in paediatrics to allow access to the small patient under the drapes. Vigilance is the watchword of monitoring!

Another important consideration is that of pressure care. Ensure that the child is not lying on any ECG or other monitoring wires; drip tubing is not pressing against the skin, and place soft cottonwool ’gamjee’ under their head, elbows and heels; particularly with long procedures.

c) Temperature control

Hypothermia is defined as a body temperature < 36° C.

Any person undergoing a general or regional anaesthetic will become hypothermic over time, unless preventative steps are taken. As alluded to earlier, children have abnormal thermoregulatory reflexes and are more likely to lose heat. Hypothermia carries with it significant morbidity and mortality – The potential for cardiac dysrhythmias; increased systemic vascular resistance; left shift of the oxygen-haemoglobin disassociation curve; a reversible coagulopathy and platelet dysfunction; apnoea; respiratory depression; postoperative shivering with a 200 % increase in O2 consumption; impaired renal and liver function; impaired drug metabolism; postoperative lethargy with poor sucking in neonates, and poor wound healing.

Temperature probes must be inserted in all children undergoing anaesthesia longer than 15 minutes. Avoid hypothermia: Transport neonates in incubators, cover the head with a cap and body with gamjees, use forced air warmers, warm theatre temperature, warm IV fluids and inspiratory gases. Theatre temperatures are usually 16 - 20° C and this allows for comfort of the surgeon and reputedly reduces microbial growth; however paediatric theatres are routinely set at higher temperatures of 22 - 24° C to benefit the children.

Hyperthermia with a body temperature > 38° C is also a concern. This used to be rare, unless there is sepsis, but is becoming more common with the overzealous use of warming devices. Malignant hyperthermia (MH), although extremely rare, occurs more commonly in children as it is often the first anaesthetic and therefore the first manifestation of this pharmacogenetic disorder. If you suspect MH, CALL FOR HELP!

d) Fluids All children require venous access and intravenous fluid therapy for anaesthesia. Some may require blood transfusions. Your aim is to maintain the intravascular volume in the peri-operative period.

Peri-operative fluid therapy includes replacement of normal losses (maintenance requirements), pre-existing fluid deficits, and ongoing surgical fluid losses (blood and possibly the third space).

Estimate maintenance fluid requirements with the easy 4 : 2 : 1 rule using the body weight: For the first 10 kg: 4 ml kg-1 hr-1 For the next 10 - 20 kg: 2 ml kg-1 hr-1 For each kg above 20 kg: 1 ml kg-1 hr-1

Example: What are the maintenance fluid requirements for a 25 kg child? Answer: (10 x 4) + (10 x 2) + (1 x 5) = 40 + 20 + 5 = 65 ml hr-1

Most intra-operative fluids are isotonic crystalloids or colloids. It may be necessary to run a glucose containing hypotonic crystalloid in addition, to prevent hypoglycaemia, e.g. ½ Darrows dextrose or ½ normal saline with dextrose. Alternatively, add dextrose to the isotonic crystalloid (e.g. Ringers lactate with dextrose added to 5 %). Beware of hyponatraemia (↓ Na+) when using hypotonic solutions

When administering fluid, meticulous attention should be paid to the removal of all air bubbles from the lines as right-to-left cardiac shunts are more common in children, e.g. small probe-patent foramen ovales or atrial- / ventricular- septal defects (ASD / VSD).

A child’s estimated blood volume is 80 ml kg-1. If intra-operative blood loss occurs, crystalloid replacement should be 3 - 4 ml for every 1 ml blood lost, and colloid replacement is 1 ml for 1 ml blood loss. If surgical losses are heavy and colloid replacement is required, we use a synthetic colloid, e.g. Voluven® or stabilised human serum (SHS) in neonates. Blood transfusion may be required if the Hb falls below 8 - 10 g dl-1 (age / pathology dependent).

4 ml kg-1 of packed red blood cells or 8 ml kg-1 of whole blood will raise the Hb by 1 g dl-1.

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e) Analgesia Analgesia forms part of the triad of anaesthesia. Children feel pain, but young children are not able to express themselves as well as adults. We can assess babies’ pain by looking at their vital signs, movements, grimacing and overall mood with the comfort scale. The visual analogue scale for pain where pain is rated by adults from 0 (no pain) to 10 (the worst pain imaginable) is replaced in older children with the faces scale. Ideally children should awaken from anaesthesia pain-free and a multi-modal approach can be used to achieve this:

Simple analgesics: Paracetamol: This can be given orally, rectally and now most effectively, intravenously (IV).

o RECTAL: Suppositories are available as 125 mg and 250 mg units. Initial / loading dose = 40 mg kg-1 with subsequent doses of 15 mg kg-1 6-hrly

o ORAL: 20 mg kg-1 6-hrly o Maximum daily dose for oral and rectal routes = 90 mg kg-1 day-1 if > 1month old; reduce to

60 mg kg-1 day-1 in neonates (liver function immaturity). o IV = PERFALGAN®: 15 mg kg-1 6-hrly – Reduce to 7,5 mg kg-1 6-hrly if < 1 month old

Beware of overdosing paracetamol when prescribing with combination agents. Nonsteroidal anti-inflamatory drugs (NSAIDs): These should be avoided in children less

than 1 year of age unless pain is poorly controlled with paracetamol alone. Remember to ask the parents or caregivers about any allergies and be particularly cautious should there be a history of asthma. Ensure adequate hydration before administering NSAIDs as they may compromise renal perfusion / function in dehydrated, hypovolaemic patients o Diclofenac (Voltaren®): 1 - 2 mg kg-1 rectally (PR) / orally (PO) 8 - 12-hrly.

Suppositories are available as 12,5 mg and 25 mg units o Ibuprofen (Brufen®): 5 - 10 mg kg-1 PO 8-hrly

A note on use of suppositories: It is inadvisable to break or cut suppositories into smaller pieces. The drug is not necessarily evenly distributed in the suppository and so you may end up under- or over- dosing.

Regional analgesia: Blocks are performed once the child is anaesthetised. Part of the anaesthetic explanation pre-operatively to the parents should include the insertion of suppositories and the block. There are many different types of neuraxial and peripheral nerve blocks, however the following are those most commonly performed and most useful. It is advisable to actively seek training and supervision with these blocks as an intern to prepare you for community service: Caudals for any upper or lower abdominal surgery or lower limb surgery.

Can cover from T4 (thoracic dermatome 4) downwards Penile blocks for circumcisions Ilio-inguinal blocks for hernia repairs Digital nerve blocks (ring blocks) for finger surgery Axillary nerve blocks for forearm and hand surgery Local anaesthetic infiltration of surgical site – Bupivacaine 0,25 % (max. dose = 2,5 mg kg-1)

Opioids Fentanyl: 1 - 3 μg kg-1 IV (short-lived) Morphine: 0,05 - 0,2 mg kg-1 IV 4-hrly Tilidine (Valoron®) drops: 1 mg kg-1 (2,5 mg per drop) PO 6-hrly

Ketamine Induction: 1 - 2 mg kg-1 IV or 6 - 10 mg kg-1 IM Analgesia: 0,25 - 0,5 mg kg-1 IV intra-operatively or as rescue analgesia in recovery Infusion: 4 ml kg-1 hr-1 – Mix 200 mg in 50 ml normal saline (4 mg ml-1) and run at body

weight (kg) = ml hr-1; i.e. 1 ml kg-1 hr-1 = 4 ml kg-1 hr-1

Very useful for burns cases. Tachyphylaxis (tolerance) does occur Oral: 10 ml kg-1, takes 15 minutes to work. Always give under supervision

Neonates and infants under 6 months are sensitive to opiate induced respiratory depression and these drugs are avoided intra-operatively. Ketamine is a good intra-operative alternative especially for the very sick neonate. Tilidine (Valoron®) drops are better for neonates and infants postoperatively, if absolutely necessary, as they can be given orally. Often the combination of regional anaesthesia with or without paracetamol PR, or IV (Perfalgan®) and then back to mother postoperatively for breastfeeding, is sufficient analgesia and comfort.

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A plethora of analgesic combinations exist on the market. What we’ve done here is to give you a simple and safe recipe for analgesia in children. Each hospital may have a different selection of analgesics. If these are combination analgesics such as Stopayne® syrup, Panadeine® or Myprodol®, please check carefully what the constituents are and what dose (mg ml-1) before using. As mentioned, a useful tactic is to give the premedication with analgesic syrup to pre-empt any surgical pain.

Postoperative analgesia is the anaesthetist’s responsibility. During the operation, you should check the prescription chart and write up appropriate analgesia for the postoperative period.

A suggested regimen: Paracetamol 6-hrly plus Tilidine (Valoron®) drops 6-hrly

(Alternating 3-hrly, i.e. child gets something every 3 hrs)

and a NSAID 8-hrly (Children do not like injections!)

Emergence and recovery

The emergence from anaesthesia can be fraught with difficulties. It is also a time when the rest of the theatre staff are relaxing as the operation is over and you may not have the necessary attention from them. Your anaesthetic assistant should be in theatre at this time. Airway complications are the most common. Suction well under direct vision and down the ETT if necessary. Make sure you have the child’s facemask and an appropriate sized oropharyngeal airway ready, should airway obstruction occur. It is better to change back to the T-piece circuit now as you have better control over the child’s ventilation with this lightweight circuit. Partial laryngospasm is common if the LMA or ETT is removed at the wrong stage; usually this is easily rectified by applying PEEP by closing off the open-end of the reservoir bag and ‘sitting it out’. If the laryngospasm is more severe, a small IV dose of propofol is useful. Avoid muscle relaxants if at all possible. It is best to wait until the child is wide-awake and breathing well, without periods of breath holding, before extubating.

Once the child is awake and maintaining their own airway; they should be placed on their side and transferred to the recovery room for further monitoring of vital signs: HR, O2 saturation and BP if necessary. Suction should be available and functioning. The child should be comfortable and pain-free; have normal vital signs, and no nausea or vomiting, before being discharged back to the ward. Sucrose-dipped dummies provides both comfort and analgesia to little ones.

For day-case surgery, the home-discharge criteria are more stringent. Usually the child stays for 2 - 4 hours postoperatively, depending on the surgery. The child must have normal vital signs, be able to take orally, have no nausea or vomiting, be pain free and able to ambulate. If the child has had a caudal, they should be moving their legs and able to urinate. The surgical site must also be inspected and should not be bleeding.

Common procedures

The procedures you will see and do as a medical officer: Dental: Extraction ENT: Tonsillectomy and adenoidectomy Myringotomy and insertion of grommets Eye surgery: Squint repair Corneoscleral laceration Meibomian cyst + molluscum contagiosum removal General surgery: Inguinal hernia Appendicectomy Gastroscopy for foreign body removal Burn surgery: Debridement + split skin grafts (SSG) Contracture release Orthopaedics: Manipulation and open reduction with external fixation (ORIF) of forearm

or lower limb Urology: Circumcision

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Who to refer

Here are some guidelines as to which children you should refer as a post internship community service officer or medical officer performing unsupervised anaesthesia:

Doctors who are not familiar with anaesthetising children should not do so. Avoid anaesthetising those under the age of 3 years without direct senior supervision.

As a medical officer, unsupervised, you should only anaesthetise ASA I - II children. Congenital anomalies are common, especially in the younger ages. Syndromes need to be

identified and potential problems for anaesthesia anticipated. Many uncommon syndromes present for surgery, and a good reference book of genetic and metabolic disorders and their impact on anaesthesia is vital in any department that anaesthetise children. Do not attempt to anaesthetise a syndromic child, even a Down’s syndrome or cerebral palsy child, as an unsupervised medical officer.

Instruments and equipment used on children need to be age- and size- appropriate. If these are not available, the child should be transferred to a centre where children can be safely anaesthetised and managed.

The younger the child is, the higher the morbidity and mortality. Avoid any children with potential for airway problems or airway abnormalities. Ask specifically

about obstructive sleep apnoea on your tonsillectomy and adenoidectomy lists, as these children should be referred to a tertiary centre.

Children with complicated disease processes or organ failure, e.g. cardiac, respiratory, liver, renal, endocrine, metabolic, etc., should be transferred to tertiary centres.

Refer any child with a suspected or undiagnosed muscle disorder, myopathy or dystrophy. Some of these disorders have an increased incidence of MH.

If you are ever uncertain or need some advice, it would be wise to contact the nearest training hospital and speak to an anaesthesia consultant / registrar, who will hopefully put you in touch with the appropriate person. If in the Western Cape, South Africa – Red Cross Childrens’ Hospital on 021 658 5003 (theatre) or Groote Schuur Hospital on 021 404 9111 and ask them to page the anaesthetist on call.

The WHO “Safe Surgery Saves Lives” checklist

The World Health Organisation (WHO) has initiated an international “Safe Surgery Saves Lives” campaign to address the problem of preventable peri-operative mortality and morbidity, especially in the developing world. This is of particular relevance to our paediatric population, as history taking and consent is invariably conducted via a third party (the parent / caregiver or other relative) and may give rise to confusion / misunderstanding, about the scope and dangers of a procedure. Preventable mistakes should be dramatically decreased with the implementation of a routine checklist. This is supported by multi-centre trials that have been performed.

This is performed at 3 stages of the procedure: Sign in - On arrival at the operating theatre Time out - Just prior to skin incision. All personnel cease any activity and apply their mind Sign out - On leaving theatre

However, this exercise should not become a paper chase, rather a mindset and culture.

Conclusion

These notes are designed to give you a practical approach to anaesthetising children. They will serve as an introduction to this field for the 4th and 5th year students, and hopefully be a more practical guide and reference to the interns, community service officers and Diploma in Anaesthesia candidates.

Paediatric anaesthesia is both a challenging and rewarding sphere of anaesthesia practise. It requires sound knowledge of paediatric medicine and surgery and a solid base of anaesthesia. Prof. Alistair Miller, paediatric surgeon at Red Cross Children’s Hospital once wrote:

“Operations on infants and small children should be performed by those who have made it their business to become familiar with paediatric surgery”

and this applies to anaesthetists and nurses as well, with regard to the peri-operative care of children.

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Appendix

LMA size selection:

Choose size 2 for children 10 - 20 kg Choose size 2½ for children 20 - 30 kg Choose size 3 for children > 30 kg ETT selection and depth guide:

AGE Wt (kg) ETT size At lip (cm) At nose (cm)

Newborn < 0,7 2,0 5,0 6

Newborn < 1 2,5 5,5 7

Newborn 1,0 3,0 6 7,5

Newborn 2,0 3,0 7 9

Newborn 3,0 3,0 8,5 10,5

Newborn 3,5 3,5 9 11

3 month 6,0 3,5 10 12

1 year 10 4,0 11 14

2 years 12 4,5 12 15

3 years 14 4,5 13 16

4 years 16 5,0 14 17

6 years 20 5,5 15 19

8 years 24 6,0 16 20

10 years 30 6,5 17 21

12 years 38 7,0 18 22

14 years 50 7,5 19 23

Types of laryngoscope blades:

Macintosh blades Miller blades

Seward blade

Wisconsin blade

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An example of the WHO “Safe Surgery Saves Lives” checklist