Diagnosis in acute medicine

171 Pages·2010·1.8 MB·English

by  Gonem

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Diagnosis in
Acute Medicine
Sherif Gonem
BM BSc MRCP
Specialty Registrar in Respiratory Medicine
East Midlands Deanery
Foreword by
Ian Pavord
DM FRCP
Consultant Physician and Honorary Professor of Medicine
Department of Respiratory Medicine, Thoracic Surgery and Allergy
University Hospitals of Leicester NHS Trust
Glenfield Hospital, Leicester
Radcliffe Publishing
Oxford (cid:129) New York
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Radcliffe Publishing Ltd
18 Marcham Road
Abingdon
Oxon OX14 1AA
United Kingdom
www.radcliffe-oxford.com
Electronic catalogue and worldwide online ordering facility.
©2010 Sherif Gonem
Sherif Gonem has asserted his right under the Copyright, Designs and Patents Act 1998 to be identi-
fied as the author of this work.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or
transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or other-
wise, without the prior permission of the copyright owner.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library.
ISBN-13: 978 184619 433 7
The paper used for the text pages of this book
is FSC certified. FSC (The Forest Stewardship
Council) is an international network to promote
responsible management of the world’s forests.
Typeset by Phoenix Photosetting, Chatham, Kent
Printed and bound by TJI Digital, Padstow, Cornwall
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Contents
Foreword v
Preface vi
About the author vii
List of abbreviations viii
Section 1: Introduction to medical diagnosis
1 Information gathering and interpretation 1
2 Diagnostic thinking 4
Section 2: Critical illness
3 The critically ill patient 7
4 Acute respiratory illness 10
5 Shock 18
6 Coma and reduced level of consciousness 22
7 Acute kidney injury 27
Section 3: Cardiovascular and respiratory presentations
8 Pleuritic chest pain 33
9 Non-pleuritic chest pain 37
10 Palpitation 41
11 Oedema 45
12 Limb pain 49
Section 4: Gastrointestinal presentations
13 Abdominal pain 51
14 Nausea and vomiting 57
15 Gastrointestinal haemorrhage 62
16 Dysphagia 65
17 Diarrhoea 68
18 Constipation 72
19 Abdominal swelling 74
20 Jaundice 77
Section 5: Neurological presentations
21 Headache 83
22 Transient loss of consciousness 88
23 Focal neurological deficit 91
24 Acute visual loss 98
25 Vertigo 101
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iv CONTENTS
Section 6: Miscellaneous presentations
26 Frequency of micturition 103
27 Haematuria 107
28 Joint pain or swelling 110
29 Back pain 114
30 Pyrexia of unknown origin 119
31 Anaemia 124
32 Skin rash 129
Section 7: Biochemical abnormalities
33 Acid–base disturbances 133
34 Hyponatraemia 140
35 Hypernatraemia 144
36 Hypokalaemia 147
37 Hyperkalaemia 150
38 Hypocalcaemia 152
39 Hypercalcaemia 154
Index 157
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Foreword
This book is aimed at medical students and junior doctors who would like to become excellent clinicians.
What is it that sets apart the excellent clinician? Unfortunately, it is more than just mastery of facts and success
in undergraduate and postgraduate examinations. Excellent clinicians have an instinct for the likely diagnosis
every bit as sharp as the professional gambler’s instinct for backing the right horse. This is honed by an
extensive knowledge of the differential diagnosis and a forensic ability to determine the likely favourites and
back markers. They are aware that odds may be altered by extraneous factors; they know which conditions
are potentially disastrous and need to be actively ruled out. Once the correct diagnosis is made, excellent
clinicians take decisive action.
This book is unique in that it addresses all these factors in relation to common symptom-based
presentations. It provides an extensive list of potential causes of a wide variety of clinical presentations.
Importantly, the common and important conditions are highlighted. This allows the clinician to begin
to estimate the pre-test probability of different conditions, information that is essential to correctly
interpret the results of clinical examinations and further investigations. The first two chapters are an
excellent introduction to the diagnostic process. I recommend that they are read carefully.
Patients are rather more interested in treatments than in diagnostic labels, and it is important to
remember that the diagnosis is only a stepping point on the way to treatment and prognostic decisions. The
book emphasises the basic principles of management; it does not attempt to deal with treatment of individual
conditions or methods of appraising these treatments. However, junior clinicians who have a sound grasp of
these principles will be in a strong position to study and evaluate more complex, disease-specific treatment
protocols.
When asked about his obsessional practice regime, the professional golfer Gary Player likes to say ‘The
harder I practice, the luckier I get.’ This maxim is as true in clinical practice as it is in golf. No book can
replace hard work on the ward and in clinics, but books can speed up the acquisition of skills by fostering
sound basic principles and developing the right instincts. Diagnosis in Acute Medicineis particularly helpful
in this regard. I strongly recommend it.
Professor Ian Pavord
Consultant Physician and Honorary Professor of Medicine
Department of Respiratory Medicine
Glenfield Hospital, University Hospitals of Leicester NHS Trust
April 2010
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Preface
Medical students and junior doctors have traditionally learned medicine disease by disease, and most medical
textbooks are still organised in this way. However, more recently the tide has begun to turn towards a more
symptom-based approach to learning clinical medicine. Many medical schools are embracing problem-based
learning, and in the postgraduate field the Curriculum for General Internal Medicine, published by the Royal
College of Physicians in 2009, specifies symptom-specific rather than disease-specific competencies to be
obtained by doctors in training. However, it should not be supposed that medical students and junior doctors
can dispense with the traditional body of knowledge comprising the epidemiology, aetiology, pathology and
clinical features of each condition, as mastery of this knowledge is essential in order to apply the problem-
based approach effectively.
The purpose of this book is to present a logical structured approach to the diagnosis and initial
management of the acutely unwell adult. For each clinical presentation, the relevant pathophysiology is first
discussed and a comprehensive table of differential diagnoses is provided, with common causes highlighted
in bold type. Next, the generic emergency management of the clinical presentation is described, and important
diagnoses that should not be missed are pointed out. Finally, the history, examination findings and
investigations that are relevant to assessing the patient’s condition or making the diagnosis are explained.
Readers of this book are encouraged to keep certain thoughts uppermost in their mind while engaged in
the diagnostic process. First, diagnosis is always a means to an end, namely treatment, and never an end in
itself. An investigation that will not contribute to a change in the patient’s management should not be
performed. Secondly, common things are common. Being able to suggest an uncommon and highly unlikely
cause of a given symptom is neither useful to the patient nor impressive to examiners. In fact it requires far
more skill and judgement to arrive at the most likelydiagnosis for a given clinical scenario, bearing in mind
that atypical presentations of common conditions occur far more often than typical presentations of rare
conditions. Finally, the reader is encouraged to subject both their own and other people’s initial impressions
to critical analysis at every stage, as many errors are made due to failure to revise the initial diagnosis in the
light of new evidence.
This book is aimed primarily at senior medical students as well as junior doctors in their first four years
after qualifying. It is during this crucial period that doctors in training lay down the foundations of their
clinical practice and hone the systems of diagnostic thought that will serve them throughout their careers. If
this volume can help its readers to think logically and systematically about the clinical problems that they
encounter in their practice, it will have achieved its aim.
Sherif Gonem
April 2010
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About the author
Sherif Gonem BM BSc MRCPgraduated from the University of Southampton in 2004 with a Bachelor of
Medicine degree, having completed an intercalated Bachelor of Science degree with first class honours the
previous year. He spent the first two years of his postgraduate training at Southampton General Hospital,
and subsequently completed his core medical training at City Hospital, Birmingham and Queen Alexandra
Hospital, Portsmouth. He passed the MRCP examination in July 2007 and was appointed to his current post
as a Specialty Registrar in Respiratory Medicine in the East Midlands Deanery in August 2008. Sherif has a keen
interest in teaching both medical students and junior doctors, and has taught on the Care of the Critically Ill
Medical Patient (CRIMP) course, as well as organising and delivering a module on acute medicine for medical
students at the University of Leicester.
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List of abbreviations
5-HIAA 5-Hydroxyindoleacetic acid
A–a Alveolar–arterial
AACG Acute angle-closure glaucoma
ABG Arterial blood gas
ACE Angiotensin-converting enzyme
AChR Acetylcholine receptor
ACTH Adrenocorticotropic hormone
ADEM Acute disseminated encephalomyelopathy
ADH Antidiuretic hormone
AG Anion gap
AIDS Acquired immune deficiency syndrome
AILD Angioimmunoblastic lymphadenopathy with dysproteinaemia
AKI Acute kidney injury
ALP Alkaline phosphatase
ALT Alanine aminotransferase
AMA Anti-mitochondrial antibody
ANA Anti-nuclear antibody
ANCA Anti-neutrophil cytoplasmic antibody
ANNA Anti-neuronal nuclear antibody
APTR Activated partial thromboplastin time
ARDS Acute respiratory distress syndrome
AST Aspartate aminotransferase
BCG Bacillus Calmette-Guérin
BRBNS Blue rubber bleb naevus syndrome
CADASIL Cerebral autosomal dominant arteriopathy with subcortical infarcts and
leukoencephalopathy
cANCA Cytoplasmic anti-neutrophil cytoplasmic antibody
CANOMAD Chronic ataxic neuropathy, ophthalmoplegia, M-protein, agglutination and disialosyl
antibodies
CEA Carcinoembryonic antigen
CIDP Chronic inflammatory demyelinating polyneuropathy
CINCA Chronic infantile neurological, cutaneous and articular syndrome
CK Creatine kinase
CMV Cytomegalovirus
CNS Central nervous system
COHb Carboxyhaemoglobin
COPD Chronic obstructive pulmonary disease
CPAP Continuous positive airway pressure
CPM Central pontine myelinolysis
CRP C-reactive protein
CSF Cerebrospinal fluid
CT Computed tomography
CTPA Computed tomography pulmonary angiogram
CXR Chest X-ray
dsDNA Double-stranded deoxyribonucleic acid
DVLA Driver and Vehicle Licensing Agency
EABV Effective arterial blood volume
EBV Epstein–Barr virus
ECG Electrocardiogram
EEG Electroencephalogram
ENA Extractable nuclear antigens
ENT Ear, nose and throat
ERCP Endoscopic retrograde cholangiopancreatogram
ESR Erythrocyte sedimentation rate
FBC Full blood count
FiO Fractional inspired oxygen concentration
2
FVC Forced vital capacity
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LIST OF ABBREVIATIONS ix
G6PD Glucose-6-phosphate dehydrogenase
GAD Glutamic acid decarboxylase
GBM Glomerular basement membrane
GCS Glasgow Coma Scale
GI Gastrointestinal
GM-CSF Granulocyte-macrophage colony-stimulating factor
GORD Gastro-oesophageal reflux disease
GTN Glyceryl trinitrate
HAE Hereditary angioedema
HELLP Haemolysis, elevated liver enzymes and low platelet
count
HaNDL Headache and neurological deficits with cerebrospinal
fluid lymphocytosis
HIDS Hyperimmunoglobulinaemia D and periodic fever syndrome
HIV Human immunodeficiency virus
HLA Human leukocyte antigen
HONK Hyperosmolar non-ketotic state
HSV Herpes simplex virus
HTLV Human T-cell lymphotropic virus
HUS Haemolytic uraemic syndrome
IBD Inflammatory bowel disease
IM Intramuscular
INR International normalised ratio
IV Intravenous
JVP Jugular venous pressure
LDH Lactate dehydrogenase
LEMS Lambert–Eaton myasthenic syndrome
LFTs Liver function tests
LKMA Liver–kidney microsomal antibodies
MC&S Microscopy, culture and sensitivities
MCV Mean corpuscular volume
MDMA 3,4-Methylenedioxymethamphetamine
MELAS Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke
MERRF Myoclonic epilepsy with ragged red fibres
MPTP 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine
MR Magnetic resonance
MRCP Magnetic resonance cholangiopancreatogram
MRI Magnetic resonance imaging
MuSK Muscle-specific kinase
NPV Negative predictive value
NRTI Nucleoside reverse transcriptase inhibitor
NSAID Non-steroidal anti-inflammatory drug
NSTEMI Non-ST elevation myocardial infarction
OGD Oesophagogastroduodenoscopy
OHSS Ovarian hyperstimulation syndrome
PaCO or PCO Arterial partial pressure of carbon dioxide
2 2
PACO Alveolar partial pressure of carbon dioxide
2
PACS Picture archiving and communications system
pANCA Perinuclear anti-neutrophil cytoplasmic antibody
PaO or PO Arterial partial pressure of oxygen
2 2
PAP Positive airway pressure
PAPA Pyogenic arthritis, pyoderma gangrenosum and acne
PAS Periodic acid Schiff
PCI Percutaneous coronary intervention
PCR Polymerase chain reaction
PET Positron emission tomography
PML Progressive multifocal leukoencephalopathy
POEMS Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin
changes
PPV Positive predictive value
PRES Posterior reversible encephalopathy syndrome
PSA Prostate-specific antigen
PTH Parathyroid hormone
PTHrP Parathyroid hormone-related peptide