This month’s case is by Barbara J. Mroz, M.D. and Robin R. Preston, Ph.D., author of Lippincott’s Illustrated Reviews: .Physiology (ISBN: 9781451175677). For more information, or to purchase your copy, visit: http://tiny.cc/PrestonLIR, with 15% off using the discount code: MEDUCATION.
The case below is followed by a choice of diagnostic tests. Select the one lettered selection that would be most helpful in diagnosing the patient’s condition.
A 54-year-old male 2 pack-per-day smoker presents to your office complaining of cough and shortness of breath (SOB). He reports chronic mild dyspnea on exertion with a daily cough productive of clear mucus. During the past week, his cough has increased in frequency and is now productive of frothy pink-tinged sputum; his dyspnea is worse and he is now short of breath sometimes even at rest. He has had difficulty breathing when lying flat in bed and has spent the past two nights sleeping upright in a recliner.
On physical examination, he is a moderately obese male with a blood pressure of 180/80 mm Hg, pulse of 98, and respiratory rate of 22. His temperature is 98.6°F. He becomes winded from climbing onto the exam table. Auscultation of the lungs reveals bilateral wheezing and crackles in the lower posterior lung fields. There is pitting edema in the lower extremities extending up to the knees.
Which if the following tests would be most helpful in confirming the correct diagnosis?
B. Arterial blood gas
C. Complete blood count
D. B-type natriuretic peptide blood test
The correct answer is B-type natriuretic peptide blood test.
Uncomfortable breathing, or feeling short of breath, is a common medical complaint with multiple causes. When approaching a patient with dyspnea, it is helpful to remember that normal breathing requires both a respiratory system that facilitates gas exchange between blood and the atmosphere, and a cardiovascular system that transports O2 and CO¬2 between the lungs and tissues. Dysfunction in either system may cause dyspnea, and wheezing (or bronchospasm) may be present in both cardiac and pulmonary disease. In this patient, the presence of lower extremity edema and orthopnea (discomfort when lying flat) are both suggestive of congestive heart failure (CHF). Elevated blood pressure (systolic of 180) and a cough productive of frothy pink sputum may also be associated symptoms. While wheezing could also be caused by COPD (chronic obstructive pulmonary disease) in the setting of chronic tobacco use, the additional exam findings of lung crackles and edema plus systolic hypertension are all more consistent with CHF.
What does the B-type natriuretic peptide blood test tell us?
When the left ventricle (LV) fails to maintain cardiac output (CO) at levels required for adequate tissue perfusion, pathways are activated to increase renal fluid retention. A rising plasma volume increases LV preload and sustains CO via the Frank-Starling mechanism. Volume loading also stimulates cardiomyocytes to release atrial- (ANP) and B-type (BNP) natriuretic peptides. BNP has a longer half-life than ANP and provides a convenient marker for volume loading. Plasma BNP levels are measured using immunoassay; levels >100 pg/mL are suggestive of overload resulting in heart failure.
How does heart failure cause dyspnea?
Increasing venous pressure increases mean capillary hydrostatic pressure and promotes fluid filtration from the vasculature. Excess filtration from pulmonary capillaries causes fluid accumulation within the alveoli (pulmonary edema) and interferes with normal gas exchange, resulting in SOB. Physical signs and symptoms caused by high volume loading include: (1) Lung crackles, caused by fluid within alveoli (2) Orthopnea. Reclining increases pulmonary capillary hydrostatic pressure through gravitational effects, worsening dyspnea when lying flat. (3) Pitting dependent edema caused by filtration from systemic capillaries, an effect also influenced by position (causing edema in the lower legs as in our ambulatory patient or in dependent areas like the sacrum in a bedridden patient).
What would an electrocardiogram show?
Heart failure can result in LV hypertrophy and manifest as a left axis deviation on an electrocardiogram (ECG), but some patients in failure show a normal ECG. An ECG is not a useful diagnostic tool for dyspnea or CHF per se.
Wouldn’t spirometry be more suitable for diagnosing the cause of dyspnea in a smoker?
Simple spirometry will readily identify the presence of airflow limitation (obstruction) as a cause of dyspnea. It's a valuable test to perform in any smoker and can establish a diagnosis of chronic obstructive pulmonary disease (COPD) if abnormal. While this wheezing patient is an active smoker who could have airflow obstruction, the additional exam findings above point more to a diagnosis of CHF.
What would an arterial blood gas show?
An arterial blood gas measures arterial pH, PaCO¬2, and PaO2. While both CHF and COPD could cause derangements in the values measured, these abnormalities would not necessarily be diagnostic (e.g., a low PaO2 could be seen in both conditions, as could an elevated PaCO¬2).
Would a complete blood count provide useful information?
A complete blood count could prove useful if anemia is a suspected cause of dyspnea.
BNP was elevated (842 pg/mL), consistent with CHF. Diuretic treatment was initiated to help reduce volume overload and an afterload reducing agent was started to lower blood pressure and improve systolic function.
An OSCE presentation by Sarah Lawrence and Oscar Swift of UCLU MedSoc aimed at clinical medical students. It will briefly go through how to perform a fundoscopy station in 5 minutes and the features of the basic pathologies (including diabetic retinopathy, hypertensive retinopathy, retinal artery/vein occlusion and others) you might see.
I am an Anatomy Professor who has taught anatomy to the medical school students in discipline based medical education system for first 10years of academic life. When I started teaching Anatomy in system-based medical education in the later half of my academic life I was surprised to find out that my students in system-based education can retain a lot of anatomy knowledge as they can visualize the application of the contents in the pathology, clinical science contents, PBL triggers and clinical skills sessions.
Surprisingly, medical schools in India still follow the discipline-based medical education. Mostly the students are forced to retain the factual knowledge of Anatomy in this system. When they are in Year 1,they study only Anatomy,Physiology and Biochemistry. Hence it is very difficult for the student to imagine the application of the knowledge of Anatomy learnt in lecture or dissection room.
For example, the students in discipline-based system learn the gross anatomy of the sternum and anterior thoracic wall. They need to memorize the importance of sternal angle without visualizing it as they are still not practising palpation of anterior thoracic wall for apex beat. I know that they learn it provided they are lucky to get a tutor who is a medical doctor, who obviously takes them to the task of palpating intercostal space through palpation of sternal angle in skeleton or over their own body surface marking.
But the lack of Clinical skills practice in traditional discipline based medical education in year 1 does not allow the student to apply their anatomy knowledge automatically.
Dr Nilesh Mitra
As the days are slowly getting longer, and spring looms in the near future, it can only be the deep inhale of the medical student ready to embrace the months of revision that lies ahead. Books are dusted off the shelves and Gray's anatomy wrenched open with an immense sigh of distain. But which book should we be pulling off the shelves? If you're anything like me then you're a medical book hoarder. Now let me "Google define" this geeky lexis lingo - a person who collects medical books (lots of medical books) and believes by having the book they will automatically do better!... I wish with a deep sigh! So when I do actually open the page of one, as they are usually thrown across the bed-room floor always closed, it is important to know which one really is the best to choose?!?
These are all the crazy thoughts of the medical book hoarder, however, there is some sanity amongst the madness. That is to say, when you find a really good medical book and get into the topic you start to learn stuff thick and fast, and before you know it you’ll be drawing out neuronal pathways and cardiac myocyte action potentials. Yet, the trick is not picking up the shiniest and most expensive book, oh no, otherwise we would all be walking around with the 130 something pounds gray’s anatomy atlas. The trick is to pick a book that speaks to you, and one in which you can get your head around – It’s as if the books each have their own personality.
Here are a list of books that I would highly recommend:
Tortora – Principles of anatomy and physiology
Tortora is a fantastic book for year 1 medical students, it is the only book I found that truly bridges the gap between A levels and medical students without going off on a ridiculous and confusing tangent.
While it lacks subtle detail, it is impressive in how simplified it can make topics appear, and really helps build a foundation to anatomy and physiology knowledge
The whole book is easy to follow and numerous pretty pictures and diagrams, which make learning a whole lot easier.
Tortora scores a whopping 8/10 by the medical book hoarder
Sherwood – From cells to systems
Sherwood is the marmite of the medical book field, you either love this book or your hate it.
For me, Sherwood used to be my bible in year two. It goes into intricate physiological detail in every area of the body. It has great explanations and really pushes your learning to a greater level than tortora in year one. The book doesn’t just regurgitate facts it really explores concepts.
I cannot be bias, and I must say that I know a number of people who hate this book in every sense of the word. A lot of people think there is too much block text without distractions such as pictures or tables. They think the text is very waffly, not getting straight to the point and sometimes discusses very advanced concepts that do not appear relevant
The truth be told, if you want to study from Sherwood you need to a very good attention span and be prepared to put in the long-hours of work so it’s not for everyone. Nonetheless, if you manage to put the effort in, you will reap the rewards!
Sherwood scores a fair 5-6/10 by the medical book hoarder
Moore & Dalley – Clinical anatomy
At first glance Moore & Dalley can be an absolute mindfield with an array of pastel colours that all amalgamate into one! It’s also full of table after table of muscle and blood vessels with complicated diagrams mixed throughout. This is not a medical book for the faint hearted, and if your foundation of anatomy is a little shakey you’ll fall further down the rabbit hole than Alice ever did.
That being said, for those who have mastered the simplistic anatomy of tortora and spent hours pondering anatomy flash cards, this may be the book for you.
Moore & Dalley does not skimp on the detail and thus if you’re willing to learn the ins and out of the muscles of the neck then look no further. Its sections are actually broken down nicely into superficial and deep structures and then into muscles, vessels, nerves and lymph, with big sections on organs.
This is a book for any budding surgeon!
Moore & Dalley scores a 6/10 by the medical book hoarder
Macleod’s clinical examination
Clinical examination is something that involves practical skills and seeing patients, using your hands to manipulate the body in ways you never realised you could. Many people will argue that the day of the examination book is over, and it’s all about learning while on the job and leaving the theory on the book shelf.
I would like to oppose this theory, with claims that a little understanding of theory can hugely improve your clinical practice.
Macleod’s takes you through basic history and examination skills within each of the main specialties, discussing examination sequences and giving detailed explanations surrounding examination findings. It is a book that you can truly relate to what you have seen or what you will see on the wards. My personal opinion is that preparation is the key, and macleod’s is the ultimate book to give you that added confidence become you tackle clinical medicine on the wards
Macleod’s clinical examination scores a 7/10 by the medical book hoarder
Oxford textbook of clinical pathology
When it comes to learning pathology there are a whole host of medical books on the market from underwood to robbins. Each book has its own price range and delves into varying degrees of complexity. Robbins is expensive and a complex of mix of cellular biology and pathophysiological mechanisms. Underwood is cheap, but lacking in certain areas and quite difficult to understand certain topics. The Oxford textbook of clinical pathology trumps them all.
The book is fantastic for any second year or third year attempting to learn pathology and classify disease. It is the only book that I have found that neatly categories diseases in a way in which you can follow, helping you to understand complications of certain diseases, while providing you with an insight into pathology.
After reading this book you’ll be sure to be able to classify all the glomerulonephritis’s while having at least some hang of the pink and purples of the histological slide.
Oxford textbook of clinical pathology scores a 8/10 by the medical book hoarder
Medical Pharmacology at glance
Pharmacology is the arch nemesis of the Peninsula student (well maybe if we discount anatomy!!), hours of time is spent avoiding the topic followed immediately by hours of complaining we are never taught any of it. Truth be told, we are taught pharmacology, it just comes in drips and drabs. By the time we’ve learnt the whole of the clotting cascade and the intrinsic mechanisms of the P450 pathway, were back on to ICE’ing the hell out of patients and forget what we learned in less than a day.
Medical pharmacology at a glance however, is the saviour of the day. I am not usually a fan of the at a glance books. I find that they are just a book of facts in a completely random order that don’t really help unless you’re an expert in the subject. The pharmacology version is different: It goes into just the right amount of detail without throwing you off the cliff with discussion about bioavailability and complex half-life curves relating to titration and renal function.
This book has the essential drugs, it has the essential facts, and it is the essential length, meaning you don’t have to spend ours reading just to learn a few facts!
In my opinion, this is one of those books that deserves the mantel piece!
Medical Pharmacology at a glance scores a whopping 9/10 by the medical book hoarder.
Anatomy colouring book
This is the last book in our discussion, but by far the greatest. After the passing comments about this book by my housemates, limited to the sluggish boy description of “it’s terrible” or “its S**t”, I feel I need to hold my own and defend this books corner. If your description of a good book is one which is engaging, interesting, fun, interaction, and actually useful to your medical learning then this book has it all.
While it may be a colouring book and allows your autistic side to run wild, the book actually covers a lot of in depth anatomy with some superb pictures that would rival any of the big anatomical textbooks. There is knowledge I have gained from this book that I still reel off during the question time onslaught of surgery.
Without a doubt my one piece of advice to all 1st and 2nd years would be BUY THIS BOOK and you will not regret it!
Anatomy colouring book scores a tremendous 10/10 by the medical book hoarder
Let the inner GEEK run free and get buying:)!!
Struggling with Pathology?
Why not join Howard Reisner, co-author of the bestselling Rubin’s Pathology, and Essentials of Rubin's Pathology, about Cell Injury and death. In it, he covers a variety of essential topics.
For more information, or to purchase your copy of one of Dr Reisner’s books, visit [www.lww.co.uk](http://lww.co.uk). Save 15% (and get free P&P) on this, and a whole host of other [LWW titles](http://lww.co.uk) when you use the code MEDUCATION when you check out!
http://www.handwrittentutorials.com - This tutorial is the first in the Cellular Respiration series. This tutorial is an overview of the process of ATP production, which includes glycolysis, the TCA cycle, beta-oxidation and the electron transport chain. For more entirely FREE tutorials and the accompanying PDFs visit http://www.handwrittentutorials.com
This video lecture from OphthoBook.com, covers common eye trauma like corneal abrasions, lid lacerations, and globe rupture. If you want to see more of these lectures, click here for the entire series.