Adult Emergency Medicine at a GlanceAdult Emergency

    Medicine at a Glance

    Thomas Hughes

    Bt.MSC, MBA, MRCP, FRCS, FCEM

    Consultant Emergency Physician

    John Radcliffe Hospital, Oxford

    Honorary Senior Lecturer in Emergency Medicine

    University of Oxford

    Jaycen Cruickshank

    MCR, FACEM

    Director of Emergency Medicine

    Ballarat Health Services, Victoria, Australia

    Senior Lecturer in Emergency Medicine

    University of Melbourne, Victoria, Australia

    A John Wiley Sons, Inc., PublicationThis edition ? rst published 2011, ? 2011 by Thomas Hughes and Jaycen Cruickshank

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    Library of Congress Cataloging-in-Publication Data

    Hughes, Thomas, MSc.

    Adult emergency medicine at a glance Thomas Hughes, Jaycen Cruickshank.

    p. ; cm.

    Includes index.

    ISBN 978-1-4051-8901-9

    1. Emergency medicine--Handbooks, manuals, etc. I. Cruickshank, Jaycen. II. Title.

    [DNLM: 1. Emergency Medicine--methods--Handbooks. 2. Adult. WB 105 H894a 2011]

    RC86.8.H84 2011

    616.02'5--dc22

    2010024551

    ISBN: 9781405189019

    A catalogue record for this book is available from the British Library.

    Set in 9 on 11.5 pt Times by Toppan Best-set Premedia Limited

    1 2011Contents 5

    Contents

    Preface and acknowledgements 7

    List of abbreviations 8

    1 Life in the Emergency Department 10

    2 Diagnosis 12

    3 Shock and intravenous ? uids 14

    4 Imaging in the Emergency Department 16

    5 Analgesia 18

    6 Airway management and sedation 20

    7 Blood gas analysis 22

    8 Trauma: primary survey 24

    9 Trauma: secondary survey 26

    10 Major head and neck injury 28

    11 Minor head and neck injury 30

    12 Wounds 32

    13 Burns 34

    14 Hand injuries 36

    15 Wrist and forearm injuries 38

    16 Shoulder and elbow injuries 40

    17 Back pain, hip and knee injuries 42

    18 Tibia, ankle and foot injuries 44

    19 Abdominal pain 46

    20 Urology problems 48

    21 Ear, nose, throat and dental problems 50

    22 Eye problems 52

    23 Obstetrics and gynaecology problems 54

    24 Toxicology: general principles 56

    25 Toxicology: speci? c poisons 58

    26 Psychiatry: self-harm and capacity 60

    27 Psychiatry: the disturbed patient 62

    28 Observational medicine 64

    29 Loss of function and independence 66

    30 Syncope, collapse and falls 68

    31 Slow heart rate 70

    32 Fast heart rate 72

    33 Cardiac arrest 74

    34 Chest pain: cardiovascular 76

    35 Chest pain: non-cardiovascular 78

    36 Shortness of breath 80

    37 Anaphylaxis 82

    38 Sepsis 84

    39 Endocrine emergencies 86

    40 Gastroenterology 88

    41 Headache 90

    42 Stroke and transient ischaemic attack 92

    43 Seizures 94

    44 Hypothermia and hyperthermia 96

    45 Pre-hospital medicine 98

    46 Major incident 100

    47 Chemical, biological, radiation, nuclear and explosive

    incidents 102

    Case studies: questions 104

    Case studies: answers 107

    Index 113Preface and Acknowledgements 7

    Preface

    Emergency Medicine has undergone a quiet revolution over the

    past twenty years due to a variety of factors that have changed the

    way medicine is practiced.

    · Increasing demand and expectations of medical care.

    · Reduction of junior doctors hours.

    · An ageing population.

    · Fragmentation of out of hours care.

    · Reduced hospital bed - stay.

    · Sub - specialisation of inpatient medical and surgical practice.

    · Litigation.

    These factors have pushed expert decision - making towards

    the front door of the hospital so that the correct diagnosis and

    treatment start as soon as possible in the patient s journey. As

    other specialties have moved away from the acute assessment and

    treatment of patients, Emergency Medicine has expanded to ? ll

    the vacuum left, and in doing so has increased its realm of practice

    substantially.

    Emergency Medicine is exciting and confronting, intimidating

    and liberating – it is the chance to exercise and hone your diag-

    nostic and practical skills in a well - supervised environment.

    Clinical staff who work in the ED have all been through the

    inevitable feelings of fear, uncertainty and doubt that come

    with the territory, and want you to experience the enjoyment

    and satisfaction of working in an area of medicine that is never

    boring.

    When trainees start Emergency Medicine, it is often the ? rst

    time they have seen patients before any other staff. To use a tra-

    ditional analogy, they have seen plenty of needles, and may be very

    good at recognising them, but now they are faced with haystacks,in which may be hidden a variety of sharp shiny objects.

    Medical textbooks usually describe topics by anatomy or pathol-

    ogy (needles), e.g. heart failure, which tends to assume the diag-

    nostic process. In this book we have tried to organise topics by

    presentation (haystacks), e.g. ‘ short of breath , and have tried to

    articulate the key features that help us ? nd the needles.

    We are both great fans of the ‘ At a Glance series, and have

    enjoyed the challenge of combining the breadth of practice of adult

    Emergency Medicine with the concise nature of the ‘ At a Glance

    format. We hope you enjoy this book and ? nd it useful as you

    explore this most dynamic area of medicine.

    Acknowledgements

    We would like to thank Karen Moore and Laura Murphy at

    Wiley - Blackwell for their support and advice (and let s face it,patience) during the elephantine gestation of the book. Also Helen

    Harvey for understanding deadlines, and Jane Fallows for doing

    such a great job with the illustrations. We thank the students of

    Oxford and Melbourne Universities, whose inquiring minds keep

    us on our toes, and whose questions stimulated us to think of new

    ways to present the information we have used here. We are both

    lucky enough to have worked with an exceptional colleague, Philip

    Catterson, whose teamwork, leadership and hard work have

    helped us to achieve success in our jobs, and from whom we have

    learned the few interpersonal skills we have.

    In addition TH would like to thank: Professor Christopher

    Bulstrode who has been an inspiration and mentor and without

    whose support the book would not have happened. My family,and particularly my wife Marina for her support. My work col-

    leagues for continuing to tolerate me most of the time, and Jackie

    and Tracey, the ED secretaries who keep me in order. Nic Weir,Rob Janas and David Bowden for their help in sourcing images

    and the ? nal preparation.

    JC would like to thank: All the people who have taught me

    along the way, particularly Trevor Jackson and Steven Pincus. My

    parents Ron and Christine for making everything possible, and my

    wife Kerry and sons Jesse and Flynn for making everything

    worthwhile.

    Thomas Hughes

    Jaycen Cruickshank 8 List of abbreviations

    List of abbreviations

    ED Emergency Department

    EDTA ethylene diamine tetraacetate

    ELISA enzyme - linked immunosorbent assay

    ENT ear, nose and throat

    EPL extensor pollicis longus

    ESR erythrocyte sedimentation rate

    ETT endotracheal tube

    FAST acronym for focused abdominal sonography in trauma;

    also face, arm, speech, time to call ambulance

    FB foreign body

    FBCFBE full blood countexamination

    FiO 2 fraction of inspired of oxygen (as %)

    FFP fresh frozen plasma

    FOOSH fall onto an outstretched hand

    GA general anaesthetic

    GA β HS group A β - haemolytic Streptococcus

    GCS Glasgow Coma ScaleScore

    GI gastrointestinal

    GP general practitioner

    H1N1 swine ? u virus

    H5N1 avian ? u virus

    HbA 1c glycated (glycosylated) haemoglobin

    HCO3--

    bicarbonate ion

    hCG human chorionic gonadotrophin

    HDU high dependency unit

    HHS hyperosmolar hyperglycaemic state

    HIV human immunode? ciency virus

    HOCM hypertrophic obstructive cardiomyopathy

    HONK hyperosmolar non - ketotic acidosis

    HR heart rate

    HVZ herpes varicella zoster

    IBS irritable bowel syndrome

    ICP intracranial pressure

    ICU intensive care unit

    IgE immunoglobulin E

    IVDU intravenous drug use

    IVF in vitro fertilisation

    IVRA intravenous regional anaesthesia

    IVU intravenous urogram

    JVP jugular venous pressure

    KUB kidneys, ureters and bladder

    LA local anaesthetic

    LCL lateral collateral ligament of knee

    LFT liver function test

    LMP last menstrual period

    LNMP last normal menstrual period

    LOC loss of consciousness

    LP lumbar puncture

    LR likelihood ratio

    LRTI lower respiratory tract infection

    MAOI monoamine oxidase inhibitor

    MAP mean arterial pressure

    MCL medial collateral ligament of knee

    MCPJ metacarpophalangeal joint

    MDI metered dose inhaler

    AAA abdominal aortic aneurysm

    ABC airway, breathing, circulation

    ABCD

    2

    acronym to assess stroke risk in a patient with TIA

    ABCDE airway, breathing, circulation, disability, exposure

    ABG arterial blood gases

    ACE angiotensin - converting enzyme

    ACh acetylcholine

    ACJ acromioclavicular joint

    ACL anterior cruciate ligament of knee

    ACS acute coronary syndrome

    ACTH adrenocorticotrophic hormone

    AD aortic dissection

    AF atrial ? brillation

    AIDS acquired immunode? ciency syndrome

    AMT4 four-point abbreviated mental test score

    AP antero - posterior

    APL abductor pollicis longus

    AV arteriovenous; also atrioventricular

    AVN atrioventricular node

    AXR abdominal X - ray

    BDZ benzodiazepine

    BP blood pressure

    bpm beats per minute

    CAGE acronym for alcohol screening questions

    CAP community - acquired pneumonia

    cAMP cyclic adenonsine monophosphate

    CBRNE chemical, biological, radiological, nuclear,explosive

    CK creatine kinase

    CNS central nervous system

    CO carbon monoxide

    COHb carboxyhaemoglobin

    COPD chronic obstructive pulmonary disease

    CPAP continuous positive airway pressure

    CPP cerebral perfusion pressure

    CPR cardiopulmonary resuscitation

    CRAO central retinal artery occlusion

    CRP C - reactive protein

    CRVO central retinal vein occlusion

    CT computed tomography

    CTPA CT pulmonary angiography

    CURB - 65 confusion, urea, respiratory rate, blood pressure,age over 65 (acronym for pneumonia severity

    factors)

    CVP central venous pressure

    CXR chest X - ray; also unit for X - ray dose, 1 CXR ≈ 3

    days background radiation

    DIPJ distal interphalangeal joint

    DKA diabetic ketoacidosis

    DM diabetes mellitus

    DSH deliberate self - harm

    DUMBELS diarrhoea, urination, miosis, bronchorrhoeabron-

    chospasm, emesis, lacrimation, salivation (acronym

    for clinical effects of organophosphate poisoning)

    DVT deep vein thrombosis List of abbreviations 9

    MI myocardial infarction

    MR magnetic resonance

    N 2 O nitrous oxide

    NAC N - acetylcysteine

    NICE National Institute for Health and Clinical Excellence

    NIV non - invasive ventilation

    NNT number needed to treat

    NNH number needed to harm

    NoF fractured neck of femur

    NSAID non - steroidal anti - in? ammatory drug

    NSTEMI non - ST segment elevation myocardial infarction

    OD overdose

    OP organophosphate

    OPG oral pantomogram

    ORIF open reduction and internal ? xation

    PA postero - anterior

    PCL posterior cruciate ligament of knee

    PE pulmonary embolism

    PEA pulseless electrical activity

    PEF peak expiratory ? ow

    PEFR peak expiratory ? ow rate

    PID pelvic in? ammatory disease

    PPCI primary percutaneous coronary intervention

    PPI proton pump inhibitor

    PPM permanent pacemaker

    PR per rectum

    PT prothrombin time

    PV per vaginam

    RA regional anaesthesia

    RBBB right bundle branch block

    RoSC return of spontaneous circulation

    SAH subarachnoid haemorrhage

    SAN sinoatrial node

    SARS severe acute respiratory syndrome

    SDH subdural haematoma

    SoB short(ness) of breath

    SOCRATES acronym for pain history

    SOL space - occupying lesion

    SSRI selective serotonin reuptake inhibitor

    STD sexually transmitted disease

    STEMI ST segment elevation myocardial infarction

    STI sexually transmitted infection

    SVT supraventricular tachycardia

    TBSA total body surface area

    TCA tricyclic antidepressant

    TFT thyroid function test

    TIA transient ischaemic attack

    TIMI thrombolysis in myocardial infarction

    TMT tarsometatarsal

    tPA tissue plasminogen activator

    U + E urea and electrolytes

    UA unstable angina

    URTI upper respiratory tract infection

    UTI urinary tract infection

    VBG venous blood gases

    VF ventricular ? brillation

    VQ ventilationperfusion

    VT ventricular tachycardia

    VVS vasovagal syncope

    WCC white cell count 10 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    1 Life in the Emergency Department

    Patients with acute health needs

    GP

    Triage

    1

    Resus

    2

    High

    acuity

    – time

    critical

    3

    High

    acuity

    – not time

    critical

    4

    Low

    acuity

    5

    Non-urgent

    Community

    ED

    Discharged patients

    Short stay

    wards

    Community

    ED

    Hospital

    Cough

    Inpatient

    units

    This chapter describes the way the Emergency Department oper-

    ates, and some of the unwritten rules. The prevalence of Emergency

    Department - based drama generates plenty of misconceptions

    about what occurs in the Emergency Department. For instance,it is generally inadvisable to say ‘ stat at the end of one s

    sentences, and neither of the authors has been mistaken for George

    Clooney!

    What h appens w hen a p atient a rrives

    at the Emergency Department?

    Alert p hone

    Also known as the ‘ red phone or sometimes ‘ the Bat - phone , this

    is the dedicated phone line that the ambulance service uses to pre -

    warn the Emergency Department of incoming patients likely to

    need resuscitation.

    Triage

    The concept of triage comes from military medicine – doing the

    most good for the most people. This ensures the most effective use

    of limited resources, and that the most unwell patients are seen

    · rst.

    Nurses rather than doctors are usually used to perform the

    triage because doctors tend to start treating patients. Systems

    of rapid assessment and early treatment by senior medical staff

    can be effective, but risk diverting attention from the most ill

    patients. Life in the Emergency Department 11

    Reception r egistration

    The reception staff are essential to the function of the Emergency

    Department: they register patients on the hospital computer

    system, source old notes and keep an eye on the waiting room.

    They have to deal with dif? cult and demanding patients, and are

    good at spotting the sick or deteriorating patient in the waiting

    room.

    Waiting r oom

    Adult and paediatric patients should have separate waiting rooms,and some sort of entertainment is a good idea. Aggression and

    dissatisfaction in waiting patients has been largely eliminated in

    the UK by the 4 - hour standard of care: all patients must be

    seen and discharged from the Emergency Department within 4

    hours.

    Treatment a reas in the

    Emergency Department

    Resuscitation b ays

    Resuscitation bays are used for critically ill and unstable patients

    with potentially life - threatening illness. They have advanced moni-

    toring facilities, and plenty of space around the patient for clinical

    staff to perform procedures. X - rays can be performed within this

    area.

    High a cuity a rea

    This is the area where patients who are unwell or injured, but who

    do not need a resuscitation bay, are managed. Medical conditions

    and elderly patients with falls are common presentations in this

    area.

    Low a cuity a rea

    The ‘ walking wounded – patients with non - life - threatening

    wounds and limb injuries – are seen here. Patients with minor

    illness are discouraged from coming to the Emergency Department,but continue to do so for a variety of reasons.

    There is a common misconception that patients in this area are

    similar to general practice or family medicine patients. Numerous

    studies have found that there is an admission rate of about 5% and

    an appreciable mortality in low acuity patients, whereas only

    about 1% of GP consultations result in immediate hospital

    admission.

    Other a reas

    Imaging

    Imaging, such as X - rays and ultrasound, are integral to Emergency

    Department function. Larger Emergency Departments have their

    own CT scanner.

    Relatives r oom

    When dealing with the relatives of a critically ill patient and break-

    ing bad news, doctors and relatives need a quiet area where infor-

    mation is communicated and digested. This room needs to be close

    to the resuscitation area.

    Observationshort stay w ard

    This is a ward area close to the Emergency Department, run by

    Emergency Department staff. This unit treats patients who would

    otherwise need hospital admission for a short time, to enable them

    to be fully stabilised and assessed. The function of these units is

    described in Chapter 28 .

    Hospital in the h ome

    Some hospitals run a ‘ hospital in the home programme for

    patients who do not need to be in hospital but who need

    certain therapy, e.g. intravenous antibiotics, anticoagulation. The

    Emergency Department is the natural interface between home

    and hospital.

    Culture of the Emergency Department

    There is a much ? atter (less hierarchical) organisational structure in

    the Emergency Department than most other areas in the hospital.

    This occurs because all levels of medical, nursing and other staff

    work together all the time, and the department cannot function

    without their cooperation. Ensuring good teamwork requires good

    leadership, an atmosphere of mutual respect and a bit of patience

    and understanding.

    The resulting atmosphere can be one of the most enjoyable and

    satisfying places to work in a hospital. A feature of this less hier-

    archical culture that surprises junior doctors is that nurses will

    question their decisions; this is a sign of a healthy culture in which

    errors are less likely to occur, and is actively encouraged.

    Emergency Department r ules

    Being a doctor in the Emergency Department is different from

    elsewhere in the hospital. There is nowhere to hide and, for

    the ? rst time in most medical careers, you are responsible for

    making the decisions. On the positive side, there are plenty

    of people around to help you, who have all been through the

    same process.

    Some basic advice:

    · Write legible, timed, dated notes.

    · Show respect for other professional groups and be prepared to

    learn from them.

    · Do not be late for your shifts; do not call in sick less than 6 hours

    before a shift.

    · Patients who re - present are high risk and need senior review.

    · Take your breaks. You need them.

    · Keep calm.

    · If in doubt, ask.

    · Do not pick up so many patients that you cannot keep track of

    them.

    · Do not avoid work or avoid seeing dif? cult patients. We do notice.

    · The nurse in charge is usually right.

    With so many people working closely together in a stressful

    atmosphere, it is inevitable that con? icts will occur. Do not

    let them fester; some ground rules for resolving such con? icts

    are:

    · Resolve it now.

    · Do it in private.

    · Do it face to face.

    · Focus on facts.

    · Criticise action, not person.

    · Agree why it is important.

    · Agree on a remedy.

    · Finish on a positive.

    12 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    2 Diagnosis

    10

    1

    0.1

    ODDS 1:20

    A type of d-dimer test has a specificity of 50% and a sensitivity of 95%:

    this allows you to calculate the likelihood ratios to rule a condition in (+LR)

    or out (–LR)

    A woman presents with a history suggestive of DVT, and her

    probability of having a DVT is low; about 5%, according to the

    Wells score (see Ch. 35).

    The d-dimer test comes back negative.

    What is the chance she has a DVT?

    Probability 5%

    0.1:20 = 1:200

    0.5%

    0.1

    1 – Sn 1 – 0.95

    1 – Sp

    = 1.9 Sn +LR =

    1 – 0.5

    0.95 = = 0.1 –LR =

    Sn 0.5

    =

    10

    1 x

    x

    =

    x

    x

    =

    x

    x

    =

    0.1

    ODDS 1:20

    If the d-dimer test had come back positive, what is the chance she

    has a DVT?

    Probability 5%

    1.9:20 = 1:10

    10%

    1.9

    The result (0.5%) is the risk of missing a DVT in this patient.

    Bearing in mind that no test is perfect, a result below 1% is

    generally taken as an acceptable level of risk

    10

    1

    0.1

    x

    x

    =

    10

    1

    0.1

    ODDS 1:1

    Probability 50%

    0.1:1 = 1:10

    10%

    0.1 5 ODDS 1:100

    Probability 1%

    5:100 = 1:20

    5%

    Despite the positive d-dimer, this patient only has a 10% chance

    of having a DVT

    This shows that this d-dimer test is useful for excluding a DVT in a low-risk population, but that a positive test does not mean a DVT is present

    A patient who has been immobile following a recent operation

    for cancer has pain in his lower leg. You assess his risk of

    DVT as about 50%, but the test comes back negative.

    What is the probability he has a DVT?

    Despite a negative d-dimer, he still has a 10% chance of having

    a DVT. D-dimer cannot ‘rule out’ DVT in a high risk patient

    A young man with mild suprapubic pain, whom you estimate has

    a 1% chance of having a UTI, has a positive urine leucocyte test

    (+ LR = 5) on dipstick testing. What is the chance he has a UTI?

    Despite a positive test with a fairly high + LR he still only has a 5%

    chance of having a UTI because the condition was so unlikely

    in the first place

    The Emergency Department is a diagnosis machine, taking

    people with a wide variety of symptoms, labelling them with

    a diagnosis, treating and then discharging them whenever

    safe to do so. There are plenty of opportunities for this process

    to go wrong, and it is important to understand how this can

    occur.

    ‘ If you listen carefully to the patient, they will tell you the

    diagnosis . W Osler

    Despite a couple of thousand years of medical education, we are

    still not really sure how the diagnostic process works.

    · Some people work forward from history, examination and a

    shortlist of differential diagnoses.

    · Others work backwards from a list of likely diagnoses to weight

    these according to symptoms and examination.

    · Experts make their diagnoses by pattern recognition.

    It may be that expertise occurs with the development of cogni-

    tive ? exibility to use multiple diagnostic strategies to integrate and

    test the result. Using t ests

    In the past, the Emergency Department used a few simple tests

    to inform decision - making. An X - ray of an injured limb has a

    binary outcome: broken not broken. As technology and the scope

    of Emergency Medicine has increased, the tests have become more

    numerous and less black and white, and there is a need to ration-

    alise and manage the uncertainty generated.

    The most common way of describing a test s performance is to

    use sensitivity and speci? city .

    Confusion m atrix

    Diagnosis 13

    SpIN – a very Speci? c test rules a condition IN .

    SnOUT – a very Sensitive test rules a condition OUT .

    Bayes theorem

    The chance of something being true or false depends not only

    on the quality of the test that one is performing, but impor-

    tantly , how likely the event is in the ? rst place.

    Thomas Bayes, an eighteenth - century English priest, deduced

    the principles that underpin the way we use tests in medicine:

    pre - t est p robability × likelihood r atio = post - t est

    p robability

    To calculate this, we use odds (like horse racing odds) rather

    than probability, but the two are obviously very closely related.

    The likelihood ratio is calculated from the test s sensitivity

    (Sn) and speci? city (Sp) and is a much better measure of a test s

    clinical usefulness in ruling a disease in (positive LR) or out

    (negative LR).

    +=

    ·

    ·=

    ·

    LR Sn

    Sp

    LR Sn

    Sp 1

    1

    How d o I d e? ne p re - t est p robability?

    The triage process uses an expert nurse to assess clinical status

    and is an assessment of the probability of serious illness. The

    fact that a patient has arrived at the Emergency Department at

    all, rather than going to their own doctor, automatically means

    the probability of signi? cant disease is relatively high.

    Clinical decision rules are widespread in Emergency

    Medicine and help codify knowledge and explicitly de? ne pre -

    test probability. However, unthinking application of such

    decision - support tools by clinicians without an appreciation of

    their ? aws and limitations results in bad decisions andor

    over - investigation.

    A history and examination taken by an experienced clinician

    remains a very good predictor of pre - test probability of disease.

    As can be seen opposite, a test applied in an inappropriate

    population group, i.e. with a pre - test probability that is very

    high or very low, will give misleading results. Tests are best

    used in populations with an intermediate probability.

    Using l ikelihood r atios in p ractice

    It helps to think of the likelihood ratio as a multiplier that tells

    you how much more or less likely a disease is, once you have the

    result.

    The particular advantage of likelihood ratios over other

    measures of a test s performance is that, as shown opposite,they can easily be applied to individual patients, not just

    populations.

    A good test for ruling in a condition has a positive likelihood

    ratio of more than 10, meaning that if the patient has a positive

    test, it is 10 times more likely that they have the disease as a

    result of the positive test.

    For example, if a very speci? c test, e.g. Troponin I, is positive,we know that myocardial damage has occurred, because the

    number of false positives (B) is very low. Similarly, if a very

    sensitive test, e.g. CT scan for abdominal aortic aneurysm (AAA),comes back as negative, we know that it is very unlikely that the

    patient has an AAA as the number of false negatives (C) will be

    very low.

    However, Emergency Departments use many tests that are

    not 100% sensitive or speci? c, and therefore a more powerful, but

    less intuitive, model is necessary to understand these tests: likeli-

    hood ratios , which are calculated from the speci? city and

    sensitivity.

    Treatment o rders

    Once the likely diagnosis has been made, a set of treatment orders

    needs to be decided and documented. A good acronym for this is

    DAVID, e.g., for an elderly patient with an open fracture of the tibia:

    · D iet – nil by mouth

    · A ctivities – elevate limb

    · V ital signs monitoring – hourly limb observations

    · I nvestigations – CXR, FBC, U + E

    · D rugstreatment – immediate i.v. antibiotics

    Test result

    Actual patient status (truth)

    Disease present Disease absent

    Positive True positive (A) False positive (B)

    Negative False negative (C) True negative (D)

    Total no.

    patients

    With disorder (A + C) Without disorder

    (B + D)

    Sensitivity = A(A + C) and Speci? city = D(B + D ) 14 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    3 Shock and i ntravenous ? uids

    Cannula (actual size) Flow rate (mlmin)

    Shock: causes

    No pressure

    Pump failurepump blockage Distribution failure Fluid failure

    Cardiac failure PE

    Cardiac tamponade

    Septic shock

    Anaphylaxis

    Spinal shock

    Wrong way

    Blood loss, e.g. GI bleed

    Penetrating trauma

    300 mmHg

    Pink 20G

    Green 18G

    Grey 16G

    Orange 14G

    50 mlmin

    100 mlmin

    200 mlmin

    350 mlmin

    100 mlmin

    200 mlmin

    400 mlmin

    700 mlmin

    Above 14G the diameter of the fluid delivery tube

    may be the limiting factor

    Intravenous ? uid therapy is a common medical treatment, but

    recently there has been a reassessment of the role of intravenous

    · uids as some of the hazards have become better understood.

    Intravenous a ccess

    Poiseulle s Law governing ? uid ? ow through a tube (assuming

    laminar ? ow):

    Flow

    L

    ∝ Pr

    4

    η

    where P = pressure difference, r = radius, η = viscosity, L = length.

    Therefore the ideal resuscitation ? uid should be non - viscous,driven by pressure through a short, wide cannula. For resuscita-

    tion, or when giving blood (viscous), a 16 G or larger cannula is

    preferred. The large veins in the antecubital fossa and the femoral

    vein are good for resuscitation but are prone to infection and

    uncomfortable for patients in the long term. A pressure bag

    in? ated to 300 mmHg doubles ? uid ? ow.

    Before cannulation the skin should be thoroughly cleaned using

    chlorhexidine in alcohol. A cannula in the forearm is (relatively)

    comfortable for the patient and less likely to become infected

    compared to other sites. Shock and intravenous ? uids 15

    Special c ases

    · Central lines are very useful in very sick patients, patients with

    poor access or patients whose ? uid balance is particularly dif? cult

    to regulate. Their length means that they are not ideal for deliver-

    ing resuscitation ? uids. Introducer sheaths offer a large bore

    central access.

    · Intraosseus needles have to be drilled into adult bone to give

    · uid, but can be life - saving. Bone marrow aspirate may be used

    for blood cross - matching.

    · Venous cut - down involves cutting the skin to be able to cannulate

    a vein under direct vision. The long saphenous vein 1 cm above

    and anterior to the medial malleolus, or the basilic vein in the

    antecubital fossa, are the most common sites for this.

    Types of i ntravenous ? uids

    Crystalloids

    Normal saline, Hartmann s solution and Ringer s lactate are solu-

    tions that match plasma osmolality. All can be used to resuscitate

    patients, and despite vigorous debate, no one variety has proven

    superior clinical outcomes.

    Dextrose

    50% dextrose is used to resuscitate hypoglycaemic patients. 10%

    dextrose is used to maintain a patient s blood sugar and prevent

    hypoglycaemia, and 5% is used to give ‘ free water to avoid over-

    loading with sodium or chloride.

    Colloids

    Colloids contain large molecules that help retain ? uid within

    the intravascular space, which improves blood pressure in the

    short term. Unfortunately these molecules leak out of damaged

    capillaries, which may cause resistant oedema in the brain and

    lungs, which increases mortality in head - injured patients. Colloids

    may be helpful in sepsis, but should only be used by senior doctors.

    Blood

    A full cross - match takes 30 minutes but type - speci? c blood should

    be available within minutes. If blood is needed before the blood

    type is known, Group O Rhesus negative blood is used.

    Whole blood as donated is the best substitute in trauma, but has

    a short shelf life (days). Separating blood cells into ‘ packed cells

    extends storage time to 3 months, but deterioration may mean that

    the cells are not fully functional for 24 hours. The citrate used to

    stabilise blood binds calcium ions, which can cause problems in

    massive transfusions ( > 50% blood volume).

    Fresh frozen plasma (FFP) or synthetic clotting factors can be

    used to correct clotting problems. Tranexamic acid, platelets and

    FFP are given as part of massive transfusion protocol.

    Temperature

    Evolution has given humans enzymes that function best at 37 ° C

    and pH ≈ 7.4. Blood clotting is impaired in a cold acidotic patient,e.g. trauma patient. Temperature < 34 ° C and pH < 7.20 reduce

    clotting to 1% of normal. Laboratory measurements at 37 ° C will

    not accurately re? ect the clinical picture. For this reason, clotting

    factors are given early in trauma resuscitation. Cold ? uids (4 ° C)

    may be given after cardiac resuscitation as part of an active cooling

    strategy to preserve brain function.

    Shock

    Shock is de? ned as inadequate tissue perfusion, i.e. not meeting

    the metabolic demands of tissue. Pulse and blood pressure are

    bedside measures of tissue perfusion, but are insensitive. pH, P CO 2 ,lactate and mixed venous blood oxygen levels, measured from a

    central venous pressure (CVP) line, are better indicators.

    Types of s hock

    The body pumps a limited amount of ? uid around a series of

    closed loops. Problems occur when the ? uid disappears, the pump

    fails or the ? uid goes to the wrong loops.

    Blood f ailure

    Blood loss may be controlled or uncontrolled, internal or external.

    Severe dehydration may cause similar problems.

    Pump f ailure

    The heart may fail due to internal pump problems, e.g. myocardial

    infarction or heart failure, which impair the ability to pump.

    Alternatively the pump may fail because there is in? ow obstruc-

    tion (cardiac tamponade, tension pneumothorax) or out? ow

    obstruction (pulmonary embolus, aortic dissection).

    Distribution f ailure

    Blood may be distributed to the wrong organs. Inappropriate

    vasodilation occurs in septic shock, anaphylaxis and spinal shock

    (due to loss of sympathetic tone below the injury) diverting blood

    away from vital organs.

    Grades of s hock

    Compensated shock BP → HR ↑

    Young adults are able to compensate for loss of blood volume by

    vasoconstriction and increased cardiac output, maintaining a good

    BP and perfusion of vital organs.

    Decompensated shock BP ↓ HR ↑

    The body s compensation mechanisms are overwhelmed, and the

    blood pressure falls rapidly.

    Fluid r esuscitation

    Traditional t eaching: ‘ Fill ‘ e m u p

    · Good blood pressure = good outcome.

    · Poor blood pressure = poor outcome.

    · Therefore give ? uidblood to achieve good blood pressure.

    Unfortunately this is an oversimpli? cation. Short - term poor

    perfusion is well tolerated and if blood loss has not been

    controlled:

    · ↑ blood pressure = ↑ blood loss.

    Increased blood loss is due to loss of vasospasm, dilution of clot-

    ting factors and dislodgement of clot.

    Current t eaching: ‘ m inimal v olume ? uid r esuscitation

    If there is uncontrolled bleeding (e.g. penetrating trauma, ruptured

    AAA), large - bore intravenous access is obtained. The minimum

    volume of ? uid necessary to maintain cerebral perfusion or a

    systolic BP of 60 – 80 mmHg is used ( ‘ permissive hypotension ). The

    priority is urgent control of bleeding in the operating theatre.

    Exception: if there is brain injury, the need to maintain cerebral

    perfusion pressure overrides hypotensive resuscitation. 16 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    4 Imaging in the Emergency Department

    The FAST scan is performed to look for free abdominal fluid – usually blood.

    The fluid tends to pool in certain areas within the peritoneal cavity

    Focussed Assessment using Sonography in Trauma – FAST Scan

    Fluid in pericardial sac ± tamponade

    Recto-vesical pouch

    Recto-uterine pouch Hepato-renal pouch

    Cardiac view

    Free fluid in the pelvis (requires full bladder)

    Pelvic view

    Normal – no fluid between kidney and spleen

    Spleno-renal view

    Normal

    Positive

    Shows fluid (blood) between liver

    and kidney

    Hepato-renal view (Morison’s Pouch)Imaging in the Emergency Department 17

    Imaging use in the Emergency Department has increased rapidly

    over the past few years due to technical advances and increasing

    pressure to move decision - making earlier in a patient s journey,and to prevent unnecessary hospital admissions. Ultrasound is

    now a core skill for senior Emergency Department doctors and

    new hospitals often have a CT scanner in the Emergency

    Department.

    Plain r adiography

    Plain radiographs interpreted by the treating clinician are used for

    the majority of Emergency Department imaging. The advent of

    digital radiography has made real - time reporting by radiologists

    easier.

    X - rays are ionising radiation and cause damage to tissues

    through which they pass. The energy released is proportional to

    the density of the tissue. Abdominal or thoracolumbar radio-

    graphs should not be performed in young people, especially

    females, without a very good reason, as the gonads are very radio-

    sensitive. In this book, X - ray doses are expressed in terms of chest

    radiographs (CXR). One CXR is approximately 3 days of back-

    ground radiation.

    X - rays are not therapeutic. If the result will not change manage-

    ment, radiographs should not be taken. Examples include uncom-

    plicated rib fractures (when not worried about a pneumothorax),coccyx pain and stubbed toes other than the big toe. Soft tissues

    are poorly shown by plain ? lms, making it an insensitive examina-

    tion for joints that rely on these for stability, e.g. knee, shoulder.

    Reading p lain r adiographs

    1 Check the patient s name and the date of the ? lm, particularly

    on digital radiography systems, which offer many opportunities

    for confusion.

    2 There should be two good views of limbs: anterior - posterior and

    lateral.

    3 If requesting imaging of more than one area, ask yourself if this

    is necessary. If not urgent, it may be better to re - examine the patient

    once they have had some analgesia, or obtain a senior opinion.

    4 You will learn more from your radiology department if you

    engage with them and ask their advice rather than expecting a

    purely technical service.

    5 Many Emergency Departments operate a system whereby the

    radiographer can ? ag an abnormality on the radiograph. You

    should not dismiss something that the radiographer has ? agged as

    abnormal without obtaining a senior opinion.

    Clinical u ltrasound

    Clinical (bedside) ultrasound use has increased exponentially with

    the availability of cheap robust ultrasound machines, and is now

    a core skill for Emergency Department doctors. Ultrasound has

    been described as the ‘ visual stethoscope and is revolutionising

    the assessment and management of patients in the Emergency

    Department.

    Ultrasound was initially used in the Emergency Department in

    the resuscitation room for:

    · Detecting abdominal aortic aneurysms (AAA).

    · Focused abdominal scanning in trauma (FAST) scans, searching

    for blood in the peritoneal cavity.

    · Central venous line placement.

    However, ultrasound use is now expanding to include:

    · Shock assessment: cardiac function, vascular ? lling, signs of

    pulmonary embolus, together with the AAA and FAST scans.

    · Basic echocardiography.

    · Deep vein thrombosis (DVT) scanning.

    · Early pregnancy scanning.

    · Hepato - biliary scanning.

    Disadvantages are that ultrasound is operator dependent,requires training and skill validation, and can divert attention

    from more important problems.

    Computed t omography s can

    As resolution and availability have increased and acquisition

    times have dropped, computed tomography (CT) has become

    an increasingly useful tool for the Emergency Department. CT is

    very good for bony injuries, and the trauma CT has proved to

    be more sensitive and speci? c than clinical examination in

    major trauma, but requires a very large radiation dose (1000

    CXR).

    Neck imaging in high - risk trauma is routinely done by CT (100

    CXR), as plain ? lms are insuf? ciently sensitive at detecting signi? -

    cant injury. Examples of high - risk injuries are a high - speed rollo-

    ver road traf? c collision, and also the elderly patient who falls

    forward, hitting their face ( ‘ fall on outstretched face ), who is at

    high risk of odontoid peg fracture, and in whom interpretation of

    plain radiographs is very dif? cult (see Chapter 11 ).

    Modern CT scanners have enough resolution and speed to be

    able to resolve cardiac anatomy including the coronary arteries,pulmonary emboli and aortic dissection (400 CXR). CT brain scan

    (100 CXR) is an essential part of the assessment of stroke or the

    unconscious patient. CT KUB (kidneys, ureters and bladder; 400

    CXRs) is the imaging of choice in renal colic.

    Magnetic r esonance s can

    Magnetic resonance (MR) scanning is rarely used in the Emergency

    Department apart from possible cauda equina syndrome (acute

    central disc prolapse pressing on the cauda equina), giving bowel

    and bladder symptoms. MR scanning can be used to avoid the

    large radiation dose incurred by CT, e.g. investigating renal colic

    in young women.

    Joints in which stability and function are mainly due to soft

    tissues, i.e. ligaments and cartilage such as the knee and shoulder,are well imaged by MR scanning, but it is generally dif? cult to

    access these directly from the Emergency Department.

    Interventional i maging

    Interventional imaging has an increasing role for a limited number

    of severe conditions. Interventional imaging is generally offered

    in larger hospitals, and together with trauma care, is one of the

    main drivers for centralisation of acute services into large

    hospitals.

    · Primary percutaneous cardiac intervention with stenting has

    become the treatment of choice for patients with myocardial

    infarction.

    · Endovascular treatments for patients with AAAs and aortic dis-

    section are increasingly used. Neurosurgical bleeding from aneu-

    rysms is treatable by coils, as is otherwise uncontrollable bleeding

    in the pelvis, e.g. from pelvic fractures. 18 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    5 Analgesia

    Intravenous regional anaesthesia

    Non-pharmacological analgesia Analgesic ladder

    Splint Plaster

    Reduce dislocation

    Sling, elevation,patient

    positioning

    Raise arm, inflate cuffs

    ↑300 mmHg

    1 Inject prilocaine 2 Manipulate fracture,plaster, X-ray

    3 Minimum 20 minutes later 4

    ↓0 mmHg

    NSAID

    Strong

    Weak

    Opiates

    Ketorolac Morphine

    Indometacin

    Tramadol

    Diclofenac

    Ibuprofen Codeine

    Paracetamol (acetaminophen)

    Patients often arrive at the Emergency Department in pain, and

    painkillers are often used before a de? nitive diagnosis is made.

    This is humane, and enables a thorough examination to be per-

    formed: there is no reason to withhold analgesia.

    Patients are asked to rate the pain out of 10, with 0 being no

    pain, and 10 being the worst pain they can imagine. This procedure

    is repeated to gauge the effectiveness of the treatment and ensure

    the pain is controlled.

    In general, a patient s reported pain is taken at face value: ‘ pain

    is what the patient feels and is treated as such. Patients seeking

    opiates may fake pain, but this is rare.

    Non - p harmacological a nalgesia

    Splinting of fractures immobilises the bones, reducing pain. A

    patient s anxiety and pain makes them tense, which may make

    pain worse: a calm, supportive atmosphere and excellent nursing

    care help to keep the patient relaxed.

    Nitrous o xide

    Nitrous oxide (N 2 O) combined with oxygen in a 1 : 1 mix in cylin-

    ders (Entonox ? ) is often used, particularly out of hospital. It is a

    short - term analgesic, effective only while the patient is breathing Analgesia 19

    the gas, as it is rapidly cleared from the body. This ‘ laughing gas

    is generally very safe, but should not be used in patients with a

    possible pneumothorax.

    Paracetamol ( a cetaminophen) and

    c ompound a nalgesics

    Paracetamol (acetaminophen) is effective and safe and can be

    given orally, rectally or intravenously. Compound analgesics

    consist of paracetamol combined with another analgesic, usually

    low - dose codeine. They come in different strengths, the weaker of

    which are sold without prescription. They are useful analgesics for

    patients to be able to take home on discharge, but prescribing the

    constituent drugs separately may allow more ? exibility.

    Moderate o piates

    · Codeine is a common component of compound analgesics, and

    is effective but tends to cause constipation. Oxycodone and dihy-

    drocodeine are more powerful variants of codeine, but offer little

    extra bene? t, and have high abuse potential.

    · Tramadol may be more effective than codeine. It has less abuse

    potential than other drugs of comparable potency but should be

    used with caution in the elderly.

    Major o piates: m orphine, f entanyl,p ethidine ( m eperidine)

    Opiates induce a feeling of well - being: patients, while still aware

    of the pain, are not distressed by it. Young patients with major

    fractures may require large doses of morphine, as will opiate

    addicts who need analgesia. Intravenous opiates are used because

    intramuscular absorption is unreliable and the intravenous route

    enables analgesia to be titrated to response.

    · Intravenous morphine is the gold standard of Emergency

    Department analgesia. It is safe, predictable and effective.

    Morphine is not as lipid soluble as other opiates, so does not give

    a signi? cant ‘ high . Morphine often causes mild histamine release

    that should not be confused with an allergic reaction. The duration

    of action of morphine is approximately 3 hours.

    · Fentanyl is a short - acting synthetic opiate that is particularly

    useful when performing short procedures, as it is cleared from the

    body within 30 minutes.

    · Pethidine (meperidine) is quite lipid soluble and therefore sought

    after by opiate addicts as it crosses the blood – brain barrier, giving

    a ‘ high . It offers no bene? ts over morphine and should not be used

    unless a patient has a de? nite allergy to morphine and there are

    no other alternatives.

    Non - s teroidal a nti - i n? ammatory d rugs

    Injectable non - steroidal anti - in? ammatory drugs (NSAIDs), e.g.

    ketorolac , are very effective in an Emergency Department setting.

    They are particularly useful in patients with broken bones, colicky

    pain (e.g. ureteric colic) and abdominal pain, but should be

    avoided in elderly patients or those with active bleeding. An

    equally effective alternative is a suppository (e.g. indometacin,diclofenac), which lasts for 16 hours.

    Oral NSAIDs are useful as they can also be given to patients on

    discharge. Ibuprofen is the least powerful, but has a relatively

    benign side - effect pro? le.

    Diclofenac and indometacin are more powerful NSAIDs but at

    a cost of increased risk of side - effects.

    Local a naesthesia and n erve b locks

    · Lidocaine 1% is the local anaesthetic (LA) most often used for

    wound management and is effective for 20 – 30 minutes without

    adrenaline, or for 40 – 60 minutes with adrenaline.

    · Adrenaline mixed with lidocaine increases length of action and

    causes vasoconstriction giving a ‘ dry wound that is much easier

    to assess, clean and close. Fear about using local anaesthetics with

    adrenaline in digits was related to high concentrations (1 : 10 000);

    less than 1 : 100 000 adrenaline is safe.

    · Bupivicaine 0.25% is a long - acting local anaesthetic, lasting for

    6 – 8 hours. Bupivicaine is highly protein bound: adrenaline does

    not increase duration of action.

    A safe maximum dose of lidocaine for wound in? ltration is 3 mg

    kg, but with adrenaline is 6 mgkg. For bupivicaine the maximum

    dose is 2 mgkg. Local anaesthetic toxicity ? rst causes perioral

    parasthesia, and then ? ts and arrhythmias, and is treated by lipid

    infusion.

    Nerve blocks can offer very effective analgesia, e.g. digital and

    femoral nerve blocks. Bupivicaine and lidocaine can be mixed to

    provide a combination of rapid onset and long duration of action.

    Local anaesthetic can also be injected into joints, e.g. for shoulder

    dislocation.

    A haematoma block can give good anaesthesia in minor frac-

    tures e.g. Colle s fractures (Chapter 15 ). The skin is carefully

    cleaned with alcohol and chlorhexidine and then up to 10 mL of

    local anaesthetic is injected into the fracture haematoma. After

    about 10 minutes reduction can be performed.

    Intravenous r egional a naesthesia

    (Bier s b lock)

    Two intravenous cannulae are sited, one in the affected limb. A

    double cuff is placed on the affected limb (usually the arm), which

    is then lifted to exsanguinate it. The cuff is then in? ated well above

    the systolic BP and local anaesthetic, e.g. prilocaine, injected.

    Bupivicaine should never be used for intravenous regional

    anaesthesia.

    After waiting 5 minutes for the local anaesthetic to have maximal

    effect, the operation, e.g. fracture reduction, is performed. The cuff

    must not be de? ated until at least 20 minutes have elapsed from

    injection of the local anaesthetic to avoid a bolus of undiluted local

    anaesthetic perfusing the heart, potentially causing asystole. 20 Adult Emergency Medicine at a Glance, 1st edition. ? Thomas Hughes and Jaycen Cruickshank. Published 2011 by Blackwell Publishing Ltd.

    6 Airway m anagement and s edation

    Oropharyngeal airway

    Measure from nose to tragus Measure from teeth to angle of jaw

    Nasopharyngeal airway

    Endotracheal tube in situ

    Head tilt

    Jaw thrust

    Laryngoscope

    Cricothyroid membrane

    Endotracheal tube

    View with a laryngoscope

    Vocal cords

    Epiglottis

    Tongue

    Needle cricothyroidotomy Surgical airway

    Laryngoscope

    Size 6 cuffed

    endotracheal tube

    Once the incision has been made NEVER let go

    Check CO2

    CXR

    Oxygen tube

    Three way tap with

    extension tube

    Cannula

    Macintosh blade,size 3

    8.0

    7.0

    Thyroid cartilage Cricothyroid

    membrane

    Cricoid

    cartilage

    Airway management in the Emergency Department is more chal-

    lenging than in the operating room as patients presenting to the

    Emergency Department must be assumed to be non - fasted, may

    be physiologically unstable, and may have head, neck or facial

    injuries.

    Oxygenation and v entilation

    Oxygenation is ensuring that the body has enough O 2 ; ventilation

    is ensuring that there is suf? cient air? ow to remove CO 2 . Oxygen

    consumption is markedly increased in the acutely unwell patient,and giving high concentrations of oxygen supports the metabolic

    demands of the body in acute illness. However, high levels of

    oxygen may paradoxically make some ischaemic injury worse, e.g.,brain heart due to vasoconstriction. A normal ‘ Hudson O 2 mask

    can give inspired oxygen (FiO 2 ) concentrations of up to 60%. They

    should not be used with O 2 < 4 Lmin to prevent CO 2 build - up. A

    mask with a reservoir bag or a self - in? ating bag - valve - mask can

    increase FiO 2 to about 90% with high ? ow ( > 10 Lmin O 2 ). A Venturi mask gives accurate low FiO 2 e.g. 28%. Nasal prongs give

    a variable amount of O 2 approx 25 – 30% but should only be used

    with low ? ow rates (2 Lmin O 2 ).

    Ventilatory f ailure

    Under normal circumstances, an increased level of CO 2 is the main

    driver to breathe. Patients with chronic lung disease, usually

    COPD, become immune to this drive. For these ‘ blue bloater

    patients, a low blood O 2 level drives breathing: their CO 2 level will

    be high.

    If high FiO 2 is given to these patients, it reduces their respiratory

    drive, increasing their CO 2 levels further, making them sleepy,which further decreases their drive to breathe, etc. An oxygen satu-

    ration target of 91% in these patients balances the need for tissue

    oxygenation against that for ventilation.

    · O 2 should be prescribed, with a target saturation

    · A patient with O 2 sat > 96% probably does not need extra O2 unless

    high metabolic need, e.g., sepsis, trauma

    · If FiO 2 has given a very high CO 2 level, reduce FiO 2 slowly

    · If in doubt, give O 2 and obtain a senior review

    Suction

    A Yankauer suction catheter is used to suction blood, vomit or

    secretions in the oropharynx. To avoid causing the patient to

    vomit, do not suction the oropharynx if the patient is conscious,and ‘ only suck where you can see .

    Airway s upport

    The jaw thrust, head tilt, oropharyngeal and nasopharangeal airways

    are illustrated opposite . The oropharyngeal airway is sized as the

    distance between the patient s teeth and the angle of the mandible.

    The nasopharyngeal airway should be the same length as the distance

    between the tip of the nose and the tragus of the ear.

    Laryngeal m ask a irway

    Emergency Department patients are not fasted and the laryngeal

    mask airway (LMA) does not prevent stomach contents being

    aspirated, nor can high ventilation pressures be achieved, as might

    be necessary in asthmatic patients. For these reasons the LMA is

    not a ‘ de? nitive airway and is not normally used in the Emergency

    Department.

    Endotracheal t ube

    The most common means to provide a de? nitive airway, the endotra-

    cheal tube (ETT), is a plastic tube that is inserted through the mouth

    (or rarely the nose) into the trachea. There is a cuff that is in? ated to

    seal against the tracheal mucosa, and a radio - opaque line to indicate

    position on X - ray. The ETT should be secured, e.g. with tape, and

    the position checked by CO 2 monitoring and a chest X - ray.

    Endotracheal tubes are sized by their internal diameter: 7.0 mm

    for an adult female, 8.0 mm for a male. There are markings indicat-

    ing distance from the tip: this is to avoid the tube being pushed

    WARNING

    Airway management and sedation 21

    too far, e.g. down the right main bronchus, which is larger and

    straighter than the left.

    The decision that the patient needs intubation is the responsibil-

    ity of the doctor managing the airway. Factors indicating need for

    intubation include:

    · Airway instability: bleeding into airways, airway burns.

    · Coma: Glasgow Coma Scale (GCS) < 9, deteriorating level of

    consciousness, loss of protective laryngeal re? exes.

    · Inadequate oxygenation: despite high inspired O 2 (FiO 2 ).

    · Inadequate ventilation: patient tireddrowsy.

    · Therapeutic reasons: control seizures, hypothermia.

    · Pragmatic reasons: combative patient, need for transport.

    A laryngoscope is needed to insert the ETT. In some countries,straight (Miller) blades are used; in others, curved (Macintosh)

    blades. These have a light to enable sight of the larynx.

    McGill s forceps have a ‘ kink in them to avoid the operator s

    hands obstructing the ? eld of vision. They are useful for removing

    loose items in the oropharynx, and manipulating the ETT.

    Surgical a irway

    Rarely, a situation occurs when it is not possible to intubate or

    ventilate a patient. In this situation, there are two options:

    · A needle cricothyroidotomy will provide short - term oxygenation,but is not a de? nitive airway, and CO 2 levels will build up.

    · A surgical airway through the cricoid membrane using a 6.0 mm

    cuffed ETT provides a de? nitive airway.

    Procedural s edation

    Procedural sedation is often performed in the Emergency

    Department to allow relocation of dislocations or for short painful

    procedures. The person performing the sedation needs appropriate

    skills and experience to manage any potential situation, including

    the need for intubation.

    The procedure should be carried out in a resuscitation bay with

    full monitoring, oxygen and suction equipment. Two doctors

    should be present at all times to ensure that the doctor administer-

    ing the sedation has their full attention on the patient s airway.

    The patient should be fasted for at least 4 hours, should give

    formal consent, and the doctor should stay with ......