Update paediatric anaesthesia

292 Pages·2017·10.86 MB·English

Education for anaesthetists worldwide
Volume 30 Number 1 June 2015
Edition Editors: Rachel Homer, Isabeau Walker, Graham Bell ISSN 1353-4882
SPECIAL EDITION
Paediatric Anaesthesia and
Critical Care
The Journal of the World Federation of Societies of Anaesthesiologists

Guest Editorial
In my opinion, paediatric anaesthesia is one of the Modern anaesthetic teaching often emphasises the latest
most interesting, rewarding and fulfilling specialities developments, but we should not forget the importance
– but I’m aware this may not be an opinion shared of the vigilant anaesthetist and the use of equipment
by all! There can be nothing more frightening than to such as the pre-cordial stethoscope, now seldom used l
a
be faced with an acutely ill or injured child when you in high resource countries.
i
don’t have any colleagues to help you or to discuss the r
Effective pain management in children undergoing
case with, and there is no time to transfer to a specialist o
surgery should always be a high priority, and the
centre, or there is no specialist centre. I imagine this t
must be the case particularly for those who only authors of the excellent section on regional anaesthesia i
d
highlight the importance of local blocks in children.
anaesthetise children occasionally. This edition of
Much is possible with simple equipment using E
Update in Anaesthesia includes a wealth of information
landmark techniques, and local blocks such as the
on different areas of paediatric anaesthetic practice,
caudal provide excellent analgesia for common surgical
and will be enormously useful to all those who care
interventions. The newer ultrasound-guided techniques
for children.
described help us to perform a wider range of blocks
Core lifesaving skills relating to airway management with great accuracy and safety, and using smaller doses
and fluid resuscitation are fundamental our practice, no of drug.
matter what the age of the patient, and maintaining these
The sections on resuscitation and critical care highlight
basic skills, and basic anaesthesia skills, should form the
some important differences between adults and
basis of our on-going professional development. For
children. For example, in adults, cardiac arrest is usually
some, this may involve spending time with a colleague
due to a primary cardiac cause, whilst in children,
during an elective operating list, so that when you need
cardiac disease is rare, and the most common cause of
to look after a child in an emergency you feel more
cardiac arrest is hypoxia or hypovolaemia, or in parts
confident. For others, it may mean updating local
of the world where halothane is still used routinely,
guidance, for instance relating to pain management
due to deep halothane anaesthesia. This is reflected in
and fluid management, and making sure that the
the resuscitation guidelines for children that emphasise
appropriate equipment is available when you need it.
identification and prevention of cardiac arrest as much
Even the normal infant airway can be difficult for those
as treatment itself. Early recognition of a seriously ill or
who are inexperienced, and it helps to have thought
injured child, whether due to a common or rare disease
about your plan in advance. Neonatal anaesthesia
condition, is essential to achieve a good outcome.
presents very particular challenges of its own.
Paediatric anaesthesia is an important sub-speciality
Preparation of a child for surgery is vital to ensure
of anaesthesia, but sadly the facilities to deliver safe
smooth and safe anaesthesia, especially in the
anaesthesia care are not always available everywhere.
presence of comorbidities. Asthma is increasingly
The mission of the WFSA is to ‘improve patient
common. Environmental pollution particularly
care and access to safe anaesthesia by uniting
affects our younger patients, and makes them more
anaesthesiologists around the world’. I believe that this
prone to respiratory infections. Whether to proceed
edition of Update in Anaesthesia, written by experts in
or to cancel the child with a common cold is often a
paediatric anaesthesia from around the globe, offers an
difficult dilemma, even for the experienced paediatric
important contribution to this mission.
anaesthetist. In any setting, even those with the best of
resources, anaesthetists have had to learn to trust their
instincts and their senses (their eyes, ears and touch).
Dusica Simic MD, PhD
Professor of Anesthesiology, Reanimation and Intensive care,
Head Department of Pediatric Anesthesia and Intensive Care,
School of Medicine, University of Belgrade, Serbia
Serbian Association of Anesthesiologist and Intensivists (SAAI) Board member;
Board member of the Section for Anesthesiology, Critical Care and Pain Therapy of Serbian Medical Society –
Pediatric anesthesia subsection president;
ESPA ACORNS member
Chair of WFSA Committee for Paediatric Anaesthesia
Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia page1
Editors notes
Dear readers
Welcome to this special edition of Update in Anaesthesia, contribution from Dr Sam Richmond, who sadly died
which focuses on paediatric anaesthesia and critical in April 2013 – Sam was a consultant neonatologist at
l
a care. Anaesthetists play an important role in the care of the City Hospitals Sunderland, UK, and was dedicated
i children in hospital, providing anaesthesia, pain relief, to furthering education in newborn resuscitation in
r
resuscitation and critical care services for some of our low- and middle-income countries.
o
most vulnerable patients.
t Providing high quality anaesthesia and critical care
i
d The speciality of paediatric anaesthesia has developed requires a trained workforce, but it can be difficult to
over the last 30-40 years as the particular requirements access refresher training in some parts of the world.
E
for safe care of the newborn, infant, young child and The WFSA and AAGBI have pioneered the ‘Safer
adolescent have been recognised. In many countries, Anaesthesia From Education’ (SAFE) short courses
there are now sub-speciality paediatric anaesthesia for physician and non-physician anaesthetists to
societies, and anaesthetists can specialise in paediatrics address these training needs. This edition of Update
as a sole area of practice. Whilst the approach ‘the child in Anaesthesia has been designed to support the SAFE
is not a miniature adult’ is important, it is also essential Paediatric Anaesthesia course, and we hope that the
to recognise that the fundamental principles of safe SAFE course participants find it useful. We also hope
anaesthetic practice can be applied to all our patients, that the regular readers of Update find it a useful
and that there is a need for the ‘generalist’ anaesthetist addition to their anaesthesia libraries; this edition will
to maintain their skills in caring for children. In many be available along with all the other WFSA education
parts of the world, more than 50% of the population resources at www.wfsahq.org.
is under 14 years, and it has been estimated that more
All previous Update in Anaesthesia articles and Tutorials
than 85% of children will require some form of surgery
of the Week are available to download for free from
before their 15th birthday – whether this is for minor
http://www.wfsahq.org/resources/virtual-library
trauma, hernia repair or tonsillectomy, to treat common
congenital abnormalities such as cleft lip and palate, or Finally, I would like to offer particular thanks to my
as the result of trauma from a road traffic accident. In fellow editors, especially to Rachel Homer for all her
all these areas, essential anaesthetic skills play a key role. hard work and dedication that has seen this project
through to completion.
This edition of Update represents the contributions
of paediatric anaesthetists from around the globe;
we are grateful to them for their hard work and for
Isabeau Walker
sharing their wisdom. We have aimed to provide
both theoretical background and practical advice that Consultant Paediatric Anaesthetist
will be useful in every day practice. The section on Great Ormond Street Hospital, London, UK
basic science includes a description of physiological
Update Team
and pharmacological differences between young
children and adults, and advice about the selection of
Editor-in-chief
equipment for children. There is a section to describe
Bruce McCormick
the anaesthetic implications of both common and
rarer co-morbidities in children. The section on Edition Editors
principles of basic clinical anaesthesia describes the Rachel Homer
essentials of preoperative preparation, intravenous fluid Isabeau Walker
management, analgesia and sedation, that are applicable Graham Bell
in any setting. The articles describing speciality areas Illustrators
of practice are written by experts in the field, and we Dave Wilkinson, Bruce McCormick
are grateful to them for making their contributions
Typesetting
so relevant to the practice of anaesthetists worldwide.
Angie Jones, sumographics (UK)
Some of the articles have been published previously in
Update in Anaesthesia and Anaesthesia Tutorial of the Printing
Week, and we have indicated this in the article where COS Printers Pte Ltd (Singapore)
relevant. We are particularly pleased to include the
page 2 Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia
Contents
1 Editorial 154 Anaesthesia for cleft and lip palate surgery
BASIC SCIENCE Ellen Rawlinson
4 Basic science relevant to practical paediatric anaesthesia 159 Anaesthesia for paediatric orthopaedic surgery
Anthony Short and Kate Stevens Tsitsi Madamombe, Jim Turner and Ollie Ross
13 Equipment in paediatric anaesthesia COMMON EMERGENCIES
Graham Bell and Rachel Homer 168 Large airway obstruction in children
23 Paediatric drawover anaesthesia N S Morton
Sarah Hodges 174 Bronchoscopy for a foreign body in a child
ANAESTHESIA AND CO-MORBID DISEASE P Dix and V Pribul
27 Anaesthesia and congenital abnormalities 178 Anaesthesia for emergency paediatric
K Ganeshalingam and T Liversedge general surgery
35 The anaesthetic management of children with Mark Newton
sickle cell disease TRAUMA IN CHILDREN
Tanya Smith and Christie Locke 187 Head injury in paediatrics
40 HIV in children and anaesthesia Delia Chimwemwe Mabedi, Paul Downie and Gregor Pollach
S Wilson and S Patel 196 Major haemorrhage in paediatric surgery
46 Anaesthesia for non-cardiac surgery in Stephen Bree and Isabeau Walker
children with congenital heart disease 199 Paediatric burns and associated injuries
Isabeau Walker A J Pittaway and N Hardcastle
58 Anaesthesia in patients with asthma, bronchiolitis 204 Stabilisation and preparation for transfer in
and other respiratory diseases paediatric trauma patients
David Liston and See Wan Tham D Easby and K L Woods
PRINCIPLES OF CLINICAL ANAESTHESIA CRITICAL CARE
65 The preparation of children for surgery 210 Paediatric intensive care in resource-limited
Nicholas Clark and Roger Langford countries
72 Perioperative analgesic pharmacology in children Rola Hallam, Mohammod Jobayer Chisti,
Glynn Williams Saraswati Kache and Jonathan Smith
77 Paediatric procedural sedation 224 Recognising the seriously ill child
D S Sethi and J Smith Laura Molyneux, Rebecca Paris and Oliver Ross
81 Perioperative fluids in children 236 Meningococcal disease in children
Catharine M Wilson and Isabeau A Walker Rob Law and Carey Francombe
88 Paediatric caudal anaesthesia 242 Intraosseous Infusion
O Raux, C Dadure, J Carr, A Rochette, X Capdevila Eric Vreede, Anamaria Bulatovic, Peter Rosseel
and Xavier Lassalle
93 Abdominal wall blocks
Nuria Masip and Steve Roberts 244 The child with malaria
Rachel A. Stoeter and Joseph Kyobe Kiwanuka
99 Upper and lower limb blocks in children
251 Acute lower respiratory disease in children
Adrian Bosenberg
Rebecca Paris, Oliver Ross, and Laura Molyneux
112 Paediatric spinal anaesthesia
RESUSCITATION
Rachel Tronci and Christophe Dadure
265 Paediatric life support
116 Paediatric difficult airway management
Bob Bingham
Michelle C White and Jonathan M Linton
270 Resuscitation at birth
ELECTIVE PROCEDURES
Sam Richmond
123 Neonatal anaesthesia
Heidi Meyer and Karmen Kemp 273 Anaphylaxis; recognition and management
Crawley S M and Rodney G R
133 Major elective surgery in children, and surgery in
remote and rural locations 279 Accidental poisoning in children
Mark Newton Susara Ribbens
141 Anaesthesia for paediatric ear, nose, MISCELLANEOUS
and throat surgery 285 Further resources available online or to
Radha Ravi and Tanya Howell download
147 Anaesthesia for paediatric eye surgery Rachel Homer
Grant Stuart
Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia page 3
Basic science relevant to practical
paediatric anaesthesia
e
c
n Anthony Short* and Kate Stevens
e
*Correspondence Email: [email protected]
i
c
S

c
i It is often said that paediatric patients are ‘not The major anatomical differences affecting
s
simply small adults’. The truth is that from the airway management in neonates and infants are
a
B premature neonate to the near-adult adolescent, as follows:
children are very diverse (see Table 1 for age
(cid:116)(cid:1) (cid:51)(cid:70)(cid:77)(cid:66)(cid:85)(cid:74)(cid:87)(cid:70)(cid:77)(cid:90)(cid:1)(cid:77)(cid:66)(cid:83)(cid:72)(cid:70)(cid:1)(cid:73)(cid:70)(cid:66)(cid:69)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)(cid:81)(cid:83)(cid:80)(cid:78)(cid:74)(cid:79)(cid:70)(cid:79)(cid:85)(cid:1)(cid:80)(cid:68)(cid:68)(cid:74)(cid:81)(cid:86)(cid:85)
definitions used in this article). This article
will consider the basic science and calculations
SUMMARY (cid:116)(cid:1) (cid:52)(cid:78)(cid:66)(cid:77)(cid:77)(cid:1)(cid:78)(cid:66)(cid:79)(cid:69)(cid:74)(cid:67)(cid:77)(cid:70)
commonly used in paediatric anaesthesia;
This article considers our challenge is to consider the anatomical, (cid:116)(cid:1) (cid:51)(cid:70)(cid:77)(cid:66)(cid:85)(cid:74)(cid:87)(cid:70)(cid:77)(cid:90)(cid:1)(cid:77)(cid:66)(cid:83)(cid:72)(cid:70)(cid:1)(cid:85)(cid:80)(cid:79)(cid:72)(cid:86)(cid:70)
the basic science and physiological and other differences that impact
calculations commonly used
on anaesthetic practice. (cid:116)(cid:1) (cid:52)(cid:73)(cid:80)(cid:83)(cid:85)(cid:1)(cid:79)(cid:70)(cid:68)(cid:76)
in paediatric anaesthesia,
including the anatomical,
ESTIMATION OF WEIGHT (cid:116)(cid:1) (cid:52)(cid:80)(cid:71)(cid:85)(cid:1)(cid:85)(cid:83)(cid:66)(cid:68)(cid:73)(cid:70)(cid:66)(cid:77)(cid:1)(cid:68)(cid:66)(cid:83)(cid:85)(cid:74)(cid:77)(cid:66)(cid:72)(cid:70)(cid:84)(cid:13)(cid:1)(cid:70)(cid:66)(cid:84)(cid:74)(cid:77)(cid:90)(cid:1)(cid:68)(cid:80)(cid:78)(cid:81)(cid:83)(cid:70)(cid:84)(cid:84)(cid:70)(cid:69)(cid:15)(cid:1)
physiological and other
It is essential that every child is weighed prior
differences relative to adults
that impact on anaesthetic to anaesthesia. This allows correct calculation These differences predispose to airway
practice. of drug doses and selection of anaesthetic obstruction, particularly if the child’s head is
equipment. In emergencies, weight can also placed on a pillow, or the soft tissues on the
be estimated from the age of the child from floor of the mouth are compressed, or the head
standard growth charts (use the weight at the is hyperextended. Ideally, maintain the child’s
50th centile), from the length of the child using head in a neutral position, or slightly extended,
a Broselow tape, or using the formulae shown in possibly with a small pad under the shoulders,
Table 2. and open the airway using a chin lift or jaw
thrust, avoiding compression of the soft tissues
AIRWAY AND RESPIRATORY TRACT
of the floor of the mouth (see Figure 1).
Anatomical differences of the paediatric airway
influence airway management and the selection Anatomical differences affecting the larynx
of appropriate equipment. include:
Table 1. Age definitions
Neonate Up to 44 weeks post conception (includes premature neonates)
Infant From 44 weeks post conception – 1 year
Anthony Short
Child 1 – 12 years of age
ST7 Anaesthetics,
Morriston Hospital, Adolescent 13 – 16 years of age
Swansea, Adult Greater than 16 years of age
South Wales
Table 2. Formulae to estimate the weight of children at different ages
Kate Stevens
Consultant Anaesthetist Age of child Formula to estimate weight in kg
and Intensivist 0-12 months (0.5 x age in months) +4
Morriston Hospital,
1-5 years (2x age in years) +8
Swansea,
6-12 years (3x age in years) +7
South Wales
page 4 Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia
Chin lift
Jaw thrust
Figure 2. The paediatric airway compared to the adult airway
(illustration by Mrs P. Klebe, used with permission)
The intubation technique in infants needs to take account of
these anatomical differences:
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child and preoxygenate; give yourself enough time
Figure 1. Chin lift and jaw thrust in a child, avoiding compression
of the soft tissues
(cid:116)(cid:1) (cid:41)(cid:66)(cid:79)(cid:69)(cid:77)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:85)(cid:74)(cid:84)(cid:84)(cid:86)(cid:70)(cid:84)(cid:1)(cid:72)(cid:70)(cid:79)(cid:85)(cid:77)(cid:90)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)(cid:68)(cid:73)(cid:80)(cid:80)(cid:84)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:66)(cid:81)(cid:81)(cid:83)(cid:80)(cid:81)(cid:83)(cid:74)(cid:66)(cid:85)(cid:70)(cid:1)(cid:84)(cid:74)(cid:91)(cid:70)(cid:69)(cid:1)
tube. Multiple attempts at intubation may result in post-
(cid:116)(cid:1) (cid:34)(cid:1)(cid:73)(cid:74)(cid:72)(cid:73)(cid:13)(cid:1)(cid:66)(cid:79)(cid:85)(cid:70)(cid:83)(cid:74)(cid:80)(cid:83)(cid:1)(cid:81)(cid:80)(cid:84)(cid:74)(cid:85)(cid:74)(cid:80)(cid:79)(cid:1)(cid:80)(cid:71)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:77)(cid:66)(cid:83)(cid:90)(cid:79)(cid:89)(cid:1)(cid:9)(cid:77)(cid:70)(cid:87)(cid:70)(cid:77)(cid:1)(cid:80)(cid:71)(cid:1)(cid:36)(cid:20)(cid:14)(cid:21)(cid:1)(cid:74)(cid:79)(cid:1)
extubation stridor
infants compared to C5-6 in adults)
(cid:116)(cid:1) (cid:49)(cid:77)(cid:66)(cid:68)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:73)(cid:70)(cid:66)(cid:69)(cid:1)(cid:74)(cid:79)(cid:1)(cid:66)(cid:1)(cid:79)(cid:70)(cid:86)(cid:85)(cid:83)(cid:66)(cid:77)(cid:1)(cid:81)(cid:80)(cid:84)(cid:74)(cid:85)(cid:74)(cid:80)(cid:79)(cid:1)(cid:80)(cid:83)(cid:1)(cid:84)(cid:77)(cid:74)(cid:72)(cid:73)(cid:85)(cid:77)(cid:90)(cid:1)(cid:70)(cid:89)(cid:85)(cid:70)(cid:79)(cid:69)(cid:70)(cid:69)(cid:13)(cid:1)
(cid:116)(cid:1) (cid:34)(cid:1) (cid:77)(cid:80)(cid:79)(cid:72)(cid:13)(cid:1) (cid:54)(cid:14)(cid:84)(cid:73)(cid:66)(cid:81)(cid:70)(cid:69)(cid:1) (cid:70)(cid:81)(cid:74)(cid:72)(cid:77)(cid:80)(cid:85)(cid:85)(cid:74)(cid:84)(cid:1) (cid:81)(cid:83)(cid:80)(cid:75)(cid:70)(cid:68)(cid:85)(cid:74)(cid:79)(cid:72)(cid:1) (cid:66)(cid:85)(cid:1) (cid:21)(cid:22)(cid:1) (cid:69)(cid:70)(cid:72)(cid:83)(cid:70)(cid:70)(cid:84)(cid:1) and stabilise the head with your right hand; use your right
posteriorly index finder to open the mouth
(cid:116)(cid:1) (cid:34)(cid:1)(cid:65)(cid:71)(cid:86)(cid:79)(cid:79)(cid:70)(cid:77)(cid:1)(cid:84)(cid:73)(cid:66)(cid:81)(cid:70)(cid:69)(cid:8)(cid:1)(cid:77)(cid:66)(cid:83)(cid:90)(cid:79)(cid:89)(cid:15)(cid:1)(cid:616)(cid:70)(cid:1)(cid:79)(cid:66)(cid:83)(cid:83)(cid:80)(cid:88)(cid:70)(cid:84)(cid:85)(cid:1)(cid:81)(cid:66)(cid:83)(cid:85)(cid:1)(cid:80)(cid:71)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:66)(cid:74)(cid:83)(cid:88)(cid:66)(cid:90)(cid:1) (cid:116)(cid:1) (cid:41)(cid:80)(cid:77)(cid:69)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:77)(cid:66)(cid:83)(cid:90)(cid:79)(cid:72)(cid:80)(cid:84)(cid:68)(cid:80)(cid:81)(cid:70)(cid:1)(cid:68)(cid:77)(cid:80)(cid:84)(cid:70)(cid:1)(cid:85)(cid:80)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:73)(cid:74)(cid:79)(cid:72)(cid:70)(cid:1)(cid:80)(cid:71)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:67)(cid:77)(cid:66)(cid:69)(cid:70)(cid:13)(cid:1)
is at the cricoid cartilage (below the vocal cords). The using the thumb and index finger of your left han.
narrowest part of the airway in adults is at the vocal cords.
(cid:116)(cid:1) (cid:42)(cid:71)(cid:1)(cid:79)(cid:70)(cid:68)(cid:70)(cid:84)(cid:84)(cid:66)(cid:83)(cid:90)(cid:13)(cid:1)(cid:86)(cid:84)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:77)(cid:74)(cid:85)(cid:85)(cid:77)(cid:70)(cid:1)(cid:235)(cid:79)(cid:72)(cid:70)(cid:83)(cid:1)(cid:80)(cid:71)(cid:1)(cid:90)(cid:80)(cid:86)(cid:83)(cid:1)(cid:77)(cid:70)(cid:71)(cid:85)(cid:1)(cid:73)(cid:66)(cid:79)(cid:69)(cid:1)(cid:85)(cid:80)(cid:1)(cid:81)(cid:83)(cid:70)(cid:84)(cid:84)(cid:1)
(cid:116)(cid:1) (cid:34)(cid:1)(cid:85)(cid:73)(cid:74)(cid:79)(cid:1)(cid:77)(cid:80)(cid:80)(cid:84)(cid:70)(cid:1)(cid:77)(cid:74)(cid:79)(cid:74)(cid:79)(cid:72)(cid:1)(cid:85)(cid:80)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:66)(cid:74)(cid:83)(cid:88)(cid:66)(cid:90)(cid:1)(cid:88)(cid:73)(cid:74)(cid:68)(cid:73)(cid:1)(cid:74)(cid:84)(cid:1)(cid:70)(cid:66)(cid:84)(cid:74)(cid:77)(cid:90)(cid:1)(cid:69)(cid:66)(cid:78)(cid:66)(cid:72)(cid:70)(cid:69) on the larynx to bring the laryngeal structures into view.
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(cid:116)(cid:1) (cid:49)(cid:77)(cid:66)(cid:68)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:85)(cid:74)(cid:81)(cid:1)(cid:80)(cid:71)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:77)(cid:66)(cid:83)(cid:90)(cid:72)(cid:79)(cid:72)(cid:80)(cid:84)(cid:68)(cid:80)(cid:81)(cid:70)(cid:1)(cid:67)(cid:77)(cid:66)(cid:69)(cid:70)(cid:1)(cid:74)(cid:79)(cid:85)(cid:80)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:87)(cid:66)(cid:77)(cid:77)(cid:70)(cid:68)(cid:86)(cid:77)(cid:66)(cid:13)(cid:1) pressures and high-inspired oxygen concentration predisposes
the space above the epiglottis (curved blade), or beneath to bronchopulmonary dysplasia and chronic lung disease.
the epiglottis (straight blade) to lift the epiglottis to expose
The airways are very small in neonates, and easily obstructed.
the larynx and vocal cord.
The flow in the airway can be described by the Hagen Pouiselle
(cid:116)(cid:1) (cid:49)(cid:66)(cid:84)(cid:84)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:85)(cid:86)(cid:67)(cid:70)(cid:1)(cid:68)(cid:66)(cid:83)(cid:70)(cid:71)(cid:86)(cid:77)(cid:77)(cid:90)(cid:1)(cid:67)(cid:70)(cid:85)(cid:88)(cid:70)(cid:70)(cid:79)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:87)(cid:80)(cid:68)(cid:66)(cid:77)(cid:1)(cid:68)(cid:80)(cid:83)(cid:69)(cid:84)(cid:13)(cid:1)(cid:86)(cid:79)(cid:69)(cid:70)(cid:83)(cid:1)
formula, assuming laminar flow:
direct vision. Do not insert the tube too far; the tracheal
length is approximately 4.5cm in most infants. Q =(∆P π r4) / (8 µ L)
Adenotonsillar hypertrophy is common in children 3 – 8 years where
of age. Airway obstruction may develop when pharyngeal
Q = volumetric flow rate
tone is lost after induction of anaesthesia; an oropharyngeal
may help to maintain a patent airway. Take care when passing ∆P = pressure drop
nasopharyngeal, nasotracheal and nasogastric tubes in these
π = a constant
children.
r = radius
Children aged 5-13 years may have loose teeth; take note of
µ - dynamic viscosity
loose teeth at your preassessment visit.
L – airway length
RESPIRATORY CONSIDERATIONS
Up to 6 months of age, infants are almost exclusively breast The flow is therefore proportional to the radius4; halving the
fed, and need to breathe through their nose rather than their radius of the airway decreases the flow rate by a factor of 16.
mouth (obligate nasal breathers). Respiratory difficulties may A small amount of airway oedema from a difficult intubation,
result if the nose is blocked, for instance due to secretions from or infection, or respiratory secretions, will significantly reduce
upper respiratory tract infections, or if a nasogastric tube is airflow and increase the work of breathing for a neonate.
present.
Respiratory mechanics in the neonates are not very efficient.
Neonates have very limited respiratory reserve, and become The rib cage is soft and compliant, and the ribs move in
hypoxic very easily. They have a high metabolic rate and (cid:85)(cid:73)(cid:70)(cid:1)(cid:73)(cid:80)(cid:83)(cid:74)(cid:91)(cid:80)(cid:79)(cid:85)(cid:66)(cid:77)(cid:1)(cid:81)(cid:77)(cid:66)(cid:79)(cid:70)(cid:1)(cid:80)(cid:79)(cid:77)(cid:90)(cid:1)(cid:9)(cid:83)(cid:66)(cid:85)(cid:73)(cid:70)(cid:83)(cid:1)(cid:85)(cid:73)(cid:66)(cid:79)(cid:1)(cid:74)(cid:79)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:73)(cid:80)(cid:83)(cid:74)(cid:91)(cid:80)(cid:79)(cid:85)(cid:66)(cid:77)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)
twice the oxygen consumption compared to older children anterior-posterior direction in adults, like a bucket handle).
and adults (6-7ml.kg-1.min-1 in neonates compared to This means the tidal volume is relatively fixed (5-7 ml.kg-1), and
3-4 ml.kg-1.min-1 in adults). the infant can only increase minute ventilation by increasing
respiratory rate (see Table 3 for normal values). Deadspace
The respiratory exchange surface is immature, with only
volumes should be kept to a minimum for neonates and infants
1/10 the number of alveoli compared to adults; in premature
to reduce the work of breathing and to reduce re-breathing.
neonates this is compounded by a lack of respiratory surfactant
that helps to reduce surface tension and to stabilise the The diaphragm is the main muscle of respiration in neonates
alveolar air spaces. The lack of surfactant in premature infants and infants, but is prone to fatigue due to a lack of type 1
predisposes them to airway collapse, poor gas exchange and (oxidative, fatigue resistant) muscle fibres. The diaphragm
increased work of breathing. Ventilation with high airway may be splinted by gastric distension due to swallowed air
Table 3. Cardiorespiratory physiology – normal values
Age (years) Respiratory rate Heart rate Blood pressure (mmHg)
(breaths per minute) (beats per minute)
Pressure increases with
Rate reduces with increasing age Rate reduces with increasing age increasing age
<1 40-30 160-110 80-90
>1-2 35-25 150-100 85-95
>2-5 30-25 140-95 85-100
>5-12 25-20 120-80 90-110
>12 20-15 100-60 100-120
page 6 Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia
(very common with crying or facemask ventilation), or due (apnoea). Apnoeas are particularly common in premature and
to bowel obstruction. It is important to consider placement of ex-premature infants, and are significant if they last longer than
a nasogastric tube to decompress the stomach in infants with 15 seconds or are associated with desaturation or bradycardia.
abdominal distension or respiratory distress. Volatile anaesthetics and opioids reduce the respiratory drive
further, and should be used cautiously in neonates, especially
The soft rib cage means that the chest wall in babies is highly
premature neonates. Consider opioid sparing techniques
compliant, and there is less ‘outward spring’ exerted by the
(paracetamol, local anaesthetic blocks) whenever possible.
rib cage, and less negative intrapleural pressure to keep the
Caffeine given orally prior to surgery has been used to reduce
lungs expanded. This results in a relatively low functional
the risk of apnoea. All ex-premature neonates <60 weeks post
residual capacity (FRC), and airway closure may occur during
conception should be monitored carefully after an anaesthetic,
normal breathing. Intercostal and sternal recession is common
ideally with an apnoea monitor if available. Term neonates are
in babies if there is any airway obstruction, or reduction in
also susceptible to apnoeas after routine anaesthesia for minor
lung compliance (for example due to infection) (see figure 3).
procedures, likely until they are at least a month old.
Tracheal tug also occurs. An infant with respiratory distress
may ‘grunt’ to maintain airway volumes – there is partial Premature infants (before 35 weeks gestational age) are at
closure (adduction) of the vocal cords during expiration, risk of retinopathy of prematurity due to abnormal vessel
which effectively provides physiological continuous positive proliferation in the vitreous of the eye, which may result
airway pressure (CPAP), and helps to keep the airways open. in haemorrhage, scarring and retinal detachment, and is a
Conversely, the presence of recession, tracheal tug and grunting common cause of blindness in this population. High PaO
2
in an older child with a more rigid rib cage is an ominous may worsen retinopathy, which is also seen in term infants
sign, and suggests very severe respiratory distress. Increased given unmonitored oxygen therapy. If oxygen therapy is
respiratory rate is an important sign of respiratory distress at required on the ward, saturations of 87-94% are acceptable in
any age. neonates, particularly premature neonates. Preoxygenation is
still indicated prior to intubation, but if possible, avoid 100%
The control of respiration is immature in neonates. Responses
FiO during the maintenance phase of anaesthesia.
to hypercarbia and hypoxia are blunted and poorly sustained, 2
and neonates often respond to hypoxia by stopping breathing Summary - practical implications for the anaesthetist:
(cid:116)(cid:1) (cid:36)(cid:80)(cid:79)(cid:84)(cid:74)(cid:69)(cid:70)(cid:83)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:79)(cid:80)(cid:83)(cid:78)(cid:66)(cid:77)(cid:1)(cid:87)(cid:66)(cid:77)(cid:86)(cid:70)(cid:84)(cid:1)(cid:71)(cid:80)(cid:83)(cid:1)(cid:83)(cid:70)(cid:84)(cid:81)(cid:74)(cid:83)(cid:66)(cid:85)(cid:80)(cid:83)(cid:90)(cid:1)(cid:83)(cid:66)(cid:85)(cid:70)(cid:1)(cid:67)(cid:90)(cid:1)(cid:66)(cid:72)(cid:70)
(cid:116)(cid:1) (cid:42)(cid:71)(cid:1)(cid:66)(cid:1)(cid:78)(cid:70)(cid:68)(cid:73)(cid:66)(cid:79)(cid:74)(cid:68)(cid:66)(cid:77)(cid:1)(cid:87)(cid:70)(cid:79)(cid:85)(cid:74)(cid:77)(cid:66)(cid:85)(cid:80)(cid:83)(cid:1)(cid:74)(cid:84)(cid:1)(cid:66)(cid:87)(cid:66)(cid:74)(cid:77)(cid:66)(cid:67)(cid:77)(cid:70)(cid:13)(cid:1)(cid:84)(cid:70)(cid:77)(cid:70)(cid:68)(cid:85)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:66)(cid:81)(cid:81)(cid:83)(cid:80)(cid:81)(cid:83)(cid:74)(cid:66)(cid:85)(cid:70)(cid:1)
tidal volume and respiratory rate for age – pressure control
ventilation is preferred
(cid:116)(cid:1) (cid:51)(cid:70)(cid:68)(cid:80)(cid:72)(cid:79)(cid:74)(cid:84)(cid:70)(cid:1) (cid:85)(cid:73)(cid:70)(cid:1) (cid:84)(cid:74)(cid:72)(cid:79)(cid:84)(cid:1) (cid:80)(cid:71)(cid:1) (cid:83)(cid:70)(cid:84)(cid:81)(cid:74)(cid:83)(cid:66)(cid:85)(cid:80)(cid:83)(cid:90)(cid:1) (cid:69)(cid:74)(cid:84)(cid:85)(cid:83)(cid:70)(cid:84)(cid:84)(cid:28)(cid:1) (cid:74)(cid:79)(cid:68)(cid:83)(cid:70)(cid:66)(cid:84)(cid:70)(cid:69)(cid:1)
respiratory rate, grunting and recessions in an older child
are extremely ominous
(cid:116)(cid:1) (cid:47)(cid:70)(cid:80)(cid:79)(cid:66)(cid:85)(cid:70)(cid:84)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)(cid:74)(cid:79)(cid:71)(cid:66)(cid:79)(cid:85)(cid:84)(cid:1)(cid:73)(cid:66)(cid:87)(cid:70)(cid:1)(cid:66)(cid:1)(cid:73)(cid:74)(cid:72)(cid:73)(cid:1)(cid:80)(cid:89)(cid:90)(cid:72)(cid:70)(cid:79)(cid:1)(cid:83)(cid:70)(cid:82)(cid:86)(cid:74)(cid:83)(cid:70)(cid:78)(cid:70)(cid:79)(cid:85)(cid:1)
and limited reserve; they become hypoxic rapidly if they
are apnoeic or if the airway is obstructed. This is particularly
important during induction of anaesthesia
(cid:116)(cid:1) (cid:52)(cid:78)(cid:66)(cid:77)(cid:77)(cid:1)(cid:68)(cid:73)(cid:74)(cid:77)(cid:69)(cid:83)(cid:70)(cid:79)(cid:1)(cid:78)(cid:66)(cid:90)(cid:1)(cid:79)(cid:80)(cid:85)(cid:1)(cid:85)(cid:80)(cid:77)(cid:70)(cid:83)(cid:66)(cid:85)(cid:70)(cid:1)(cid:81)(cid:83)(cid:70)(cid:80)(cid:89)(cid:90)(cid:72)(cid:70)(cid:79)(cid:66)(cid:85)(cid:74)(cid:80)(cid:79)(cid:1)(cid:88)(cid:70)(cid:77)(cid:77)(cid:13)(cid:1)(cid:67)(cid:86)(cid:85)(cid:1)
you should always try
(cid:116)(cid:1) (cid:40)(cid:66)(cid:84)(cid:85)(cid:83)(cid:74)(cid:68)(cid:1)(cid:69)(cid:74)(cid:84)(cid:85)(cid:70)(cid:79)(cid:84)(cid:74)(cid:80)(cid:79)(cid:1)(cid:84)(cid:81)(cid:77)(cid:74)(cid:79)(cid:85)(cid:84)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:69)(cid:74)(cid:66)(cid:81)(cid:73)(cid:83)(cid:66)(cid:72)(cid:78)(cid:13)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:78)(cid:66)(cid:74)(cid:79)(cid:1)(cid:78)(cid:86)(cid:84)(cid:68)(cid:77)(cid:70)(cid:1)
of respiration in neonates and infants; consider a nasogastric
tube (NGT) in cases of gastric distension
(cid:116)(cid:1) (cid:36)(cid:49)(cid:34)(cid:49)(cid:16)(cid:49)(cid:38)(cid:38)(cid:49)(cid:1)(cid:9)(cid:81)(cid:80)(cid:84)(cid:74)(cid:85)(cid:74)(cid:87)(cid:70)(cid:1)(cid:70)(cid:79)(cid:69)(cid:14)(cid:70)(cid:89)(cid:81)(cid:74)(cid:83)(cid:66)(cid:85)(cid:80)(cid:83)(cid:90)(cid:1)(cid:81)(cid:83)(cid:70)(cid:84)(cid:84)(cid:86)(cid:83)(cid:70)(cid:10)(cid:1)(cid:66)(cid:83)(cid:70)(cid:1)(cid:86)(cid:84)(cid:70)(cid:71)(cid:86)(cid:77)(cid:1)
and may help avoid airway collapse and maintain oxygen
saturations in neonates and infants
Figure 3. Tracheal tug, subcostal and intercostal recession is
common in babies with respiratory distress (illustration by Mrs P. (cid:116)(cid:1) (cid:52)(cid:70)(cid:77)(cid:70)(cid:68)(cid:85)(cid:1)(cid:66)(cid:79)(cid:66)(cid:70)(cid:84)(cid:85)(cid:73)(cid:70)(cid:85)(cid:74)(cid:68)(cid:1)(cid:70)(cid:82)(cid:86)(cid:74)(cid:81)(cid:78)(cid:70)(cid:79)(cid:85)(cid:1)(cid:88)(cid:74)(cid:85)(cid:73)(cid:1)(cid:77)(cid:80)(cid:88)(cid:1)(cid:69)(cid:70)(cid:66)(cid:69)(cid:84)(cid:81)(cid:66)(cid:68)(cid:70)(cid:1)(cid:87)(cid:80)(cid:77)(cid:86)(cid:78)(cid:70)(cid:1)
Klebe, used with permission) to reduce the work of breathing
Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia page 7
(cid:116)(cid:1) (cid:46)(cid:80)(cid:79)(cid:74)(cid:85)(cid:80)(cid:83)(cid:1)(cid:66)(cid:77)(cid:77)(cid:1)(cid:67)(cid:66)(cid:67)(cid:74)(cid:70)(cid:84)(cid:1)(cid:71)(cid:80)(cid:83)(cid:1)(cid:66)(cid:81)(cid:79)(cid:80)(cid:70)(cid:66)(cid:84)(cid:1)(cid:66)(cid:71)(cid:85)(cid:70)(cid:83)(cid:1)(cid:84)(cid:86)(cid:83)(cid:72)(cid:70)(cid:83)(cid:90)(cid:28)(cid:1)(cid:70)(cid:89)(cid:14)(cid:81)(cid:83)(cid:70)(cid:78)(cid:66)(cid:85)(cid:86)(cid:83)(cid:70)(cid:1) Venous return from the lungs to the left atrium increases and
babies are at increased risk until they are 60 weeks post the pressure gradient reverses across the foramen ovale, which
conception begins to close. The pressure in the pulmonary artery falls,
and blood flow through the ductus arteriosus is reversed so
(cid:116)(cid:1) (cid:42)(cid:71)(cid:1) (cid:80)(cid:89)(cid:90)(cid:72)(cid:70)(cid:79)(cid:1) (cid:85)(cid:73)(cid:70)(cid:83)(cid:66)(cid:81)(cid:90)(cid:1) (cid:74)(cid:84)(cid:1) (cid:83)(cid:70)(cid:82)(cid:86)(cid:74)(cid:83)(cid:70)(cid:69)(cid:13)(cid:1) (cid:52)(cid:81)(cid:48) 87-94% is
2 that blood flows from the aorta to the pulmonary artery. The
recommended in premature neonates.
ductus arteriosus begins to constrict due to increasing PaO
2
and decreasing levels of prostaglandin E (PGE ). This is a
CARDIOVASCULAR CONSIDERATIONS 2 2
transitional period. The ductus does not undergo full fibrosis
Transitional circulation for one month, and the foramen ovale may reopen in the first
5 years of life. Large decreases in systemic vascular resistance
With a newborn’s first breath, there is a transition from the
or increases in pulmonary vascular resistance due to hypoxia,
fetal circulation (gas transfer at the placenta) to the newborn
hypercarbia, sepsis or acidosis in the first few weeks after birth
circulation (gas transfer at the lungs). Pulmonary vascular
may cause the pulmonary vascular resistance to rise, and the
resistance decreases with the first breath by up to 80% (mainly
fetal shunts to reopen with right to left shunting; the baby will
due to the rise in PaO and in part due to the rise in pH and the
2
become very cyanosed as deoxygenated blood flows from the
fall in PaCO at birth). Systemic vascular resistance increases
2
pulmonary artery to the aorta and pulmonary blood flow falls.
with clamping of the umbilical cord hence exclusion of the low
Worsening hypoxia leads to increased pulmonary vascular
resistance placental bed (see Figure 4).
resistance, which further amplifies the right to left shunt. This
is called persistent pulmonary hypertension of the newborn
(PPHN).
Neonatal considerations
(cid:34)(cid:85)(cid:1)(cid:67)(cid:74)(cid:83)(cid:85)(cid:73)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:83)(cid:74)(cid:72)(cid:73)(cid:85)(cid:1)(cid:87)(cid:70)(cid:79)(cid:85)(cid:83)(cid:74)(cid:68)(cid:77)(cid:70)(cid:1)(cid:74)(cid:84)(cid:1)(cid:66)(cid:1)(cid:84)(cid:74)(cid:78)(cid:74)(cid:77)(cid:66)(cid:83)(cid:1)(cid:84)(cid:74)(cid:91)(cid:70)(cid:1)(cid:85)(cid:80)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:77)(cid:70)(cid:71)(cid:85)(cid:1)(cid:87)(cid:70)(cid:79)(cid:85)(cid:83)(cid:74)(cid:68)(cid:77)(cid:70)(cid:13)(cid:1)
due to the high PVR in fetal life. There is therefore right-sided
dominance on the newborn ECG. By two months of age the
(cid:77)(cid:70)(cid:71)(cid:85)(cid:1)(cid:87)(cid:70)(cid:79)(cid:85)(cid:83)(cid:74)(cid:68)(cid:77)(cid:70)(cid:1)(cid:74)(cid:84)(cid:1)(cid:85)(cid:88)(cid:74)(cid:68)(cid:70)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:84)(cid:74)(cid:91)(cid:70)(cid:1)(cid:80)(cid:71)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:83)(cid:74)(cid:72)(cid:73)(cid:85)(cid:13)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)(cid:66)(cid:1)(cid:77)(cid:70)(cid:71)(cid:85)(cid:1)(cid:69)(cid:80)(cid:78)(cid:74)(cid:79)(cid:66)(cid:79)(cid:85)(cid:1)
ECG is seen from 4 – 6 months of age. As the heart grows,
(cid:85)(cid:73)(cid:70)(cid:1)(cid:49)(cid:51)(cid:1)(cid:74)(cid:79)(cid:85)(cid:70)(cid:83)(cid:87)(cid:66)(cid:77)(cid:13)(cid:1)(cid:50)(cid:51)(cid:52)(cid:1)(cid:69)(cid:86)(cid:83)(cid:66)(cid:85)(cid:74)(cid:80)(cid:79)(cid:1)(cid:66)(cid:79)(cid:69)(cid:1)(cid:85)(cid:73)(cid:70)(cid:1)(cid:50)(cid:51)(cid:52)(cid:1)(cid:84)(cid:74)(cid:91)(cid:70)(cid:1)(cid:66)(cid:77)(cid:77)(cid:1)(cid:74)(cid:79)(cid:68)(cid:83)(cid:70)(cid:66)(cid:84)(cid:70)(cid:15)
The newborn period is a time of rapid growth and development.
High tissue oxygen delivery is required for the developing brain
and other organs. The cardiac output is therefore relatively
high compared to adults (see Table 4).
The ventricles are immature, and less compliant, with a
relatively fixed stroke volume (1.5mls.kg-1 at birth), so increase
in cardiac output is achieved through an increase in heart rate,
rather than an increase in stroke volume as in adults (see table
3). This limits the ability to increase the cardiac output with a
fluid challenge in a neonate, and it is easy to push the neonate
into pulmonary oedema if too much fluid is given. Bradycardia
(most commonly due to hypoxia) will reduce both cardiac
output and blood pressure significantly.
In the newborn, vagal tone predominates. Hypoxia, airway
manipulation, surgical stimuli and deep halothane anaesthesia
are all likely to provoke bradycardia. Hypoxia should always
be corrected and a dose of atropine (20mcg.kg-1) should always
be drawn up when anaesthetising children. Start CPR if the
HR drops below 60 bpm; small doses of adrenaline up to 10
Figure 4. Fetal and neonatal circulation (illustration by Mrs P. mcg.kg-1 may be required if the heart rate is unresponsive to
Klebe, used with permission) atropine.
page 8 Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia