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.
This is an excerpt from "Fluids and Electrolytes Made Incredibly Easy! 1st UK Edition" by William N. Scott. For more information, or to purchase your copy, visit: http://tiny.cc/Fande. Save 15% (and get free P&P) on this, and a whole host of other LWW titles at lww.co.uk when you use the code MEDUCATION when you check out!
The chemical reactions that sustain life depend on a delicate balance – or homeostasis – between acids and bases in the body. Even a slight imbalance can profoundly affect metabolism and essential body functions. Several conditions, such as infection or trauma, and certain medications can affect acid-base balance. However, to understand this balance, you need to understand some basic chemistry.
Understanding acids and bases requires an understanding of pH, a calculation based on the concentration of hydrogen ions in a solution. It may also be defi ned as the amount of acid or base within a solution.
Acids consist of molecules that can give up, or donate, hydrogen ions to other molecules. Carbonic acid is an acid that occurs naturally in the body. Bases consist of molecules that can accept hydrogen ions; bicarbonate is one example of a base.
A solution that contains more base than acid has fewer hydrogen ions, so it has a higher pH. A solution with a pH above 7 is a base, or alkaline.
A solution that contains more acid than base has more hydrogen ions, so it has a lower pH. A solution with a pH below 7 is an acid, or acidotic.
Getting your PhD in pH
A patient’s acid-base balance can be assessed if the pH of their blood is known. Because arterial blood is usually used to measure pH, this discussion focuses on arterial samples.
Arterial blood is normally slightly alkaline, ranging from 7.35 to 7.45. A pH level within that range represents a balance between the concentration of hydrogen ions and bicarbonate ions. The pH of blood is generally maintained in a ratio of 20 parts bicarbonate to 1 part carbonic acid. A pH below 6.8 or above 7.8 is usually fatal.
Under certain conditions, the pH of arterial blood may deviate significantly from its normal narrow range. If the blood’s hydrogen ion concentration increases or bicarbonate level decreases, pH may decrease. In either case, a decrease in pH below 7.35 signals acidosis.
If the blood’s bicarbonate level increases or hydrogen ion concentration decreases, pH may rise. In either case, an increase in pH above 7.45 signals alkalosis.
Regulating acids and bases
A person’s well-being depends on their ability to maintain a normal pH. A deviation in pH can compromise essential body processes, including electrolyte balance, activity of critical enzymes, muscle contraction and basic cellular function. The body normally maintains pH within a narrow range by carefully balancing acidic and alkaline elements. When one aspect of that balancing act breaks down, the body can’t maintain a healthy pH as easily, and problems arise.
Another presentation covering the GI tract. All information is from NICE guidance & Clinical Knowledge Summaries & Oxford Handbooks.
Images either made by me or from Google. Feedback is appreciated and please check out my other presentations!
During our antibiotics teaching at medical school we were told that a recent survey of junior doctors had revealed that a significant proportion didn't realise that augmentin, tazocin, and carbopenems were penicillins and as such should not be given to those with known allergies. I devised a "mind-map" summarising the main antibiotics in use using information from the BNF and my own lecture notes. For me, seeing the information laid out in this manner, pinned above my desk as I work, helps me remember the major classes, their relationships with one another, and their major side-effects.
It's been a while since I've added any thoughts to this blog. In that time I have finished my Obs/Gynae placement, I have spent a week on labour ward, and done my first week of my 4th year surgical placement. All the while cramming in revision between various activities and general staying alive measures. This, I feel, is how most people who are sitting their final written exams are spending their time, so I don't feel so alone.
I just want to bring to the attention one amazing incident that happened on my labour ward week. I was on a night shift, there wasn't a lot going on. Absolutely everyone was knackered, the registrar who'd been on nights for the past week was just chatting to me. I have never seen someone look so tired. The emergency alarm went off and a lady had a cord prolapse, which is an obstetric emergency with a high foetal mortality rate. Now I think it's amazing that the doctor went from nearly falling asleep to switched on 'surgical-mode' in an instant, successfully performed the C-section, delivering the baby in about a minute, then went back to being absolutely knackered and let the SHO close up the wound.
It just really impressed me and I felt it was something worth sharing. Actually I was incredibly surprised that I enjoyed Obs/Gynae. Women's health was a placement I was dreading, it was my last major knowledge gap and I didn't have a clue what it was going to be like. If my tutor for the block does read this, thank you for all your help and getting me involved in everything. I would encourage other students who are going into it and feeling any level of apprehension to just throw yourselves into it and give 110% effort. It is a great placement for practicing transferable skills (this is important to remember, especially if you don't have any desire to go into it you CAN transfer and practice skills from elsewhere!) and getting heavily involved in patient care.
Also I'd like to point out the Mother and Baby were fine :)
This is an excerpt from "Wound Care Made Incredibly Easy! 1st UK Edition" by Julie Vuolo For more information, or to purchase your copy, visit: http://tiny.cc/woundcare. Save 15% (and get free P&P) on this, and a whole host of other LWW titles at http://lww.co.uk when you use the code MEDUCATION when you check out!
A burn is an acute wound caused by exposure to thermal extremes, electricity, caustic chemicals or radiation. The degree of tissue damage caused by a burn depends on the strength of the source and the duration of contact or exposure. Around 250,000 people per year sustain burn injuries in the UK (NBCRC 2001). Because of the specialist care burns require, they are considered here separately from other traumatic wounds.
Types of burns
Burns can be classified by cause or type. Knowing the type of burn will help you to plan the right care for your patient.
The most common type of burn, thermal burns can result from virtually any misuse or mishandling of fire, combustible products, hot fluids and fat or coming into contact with a hot object. Playing with matches, pouring petrol onto a BBQ, spilling hot coffee, touching hot hair straighteners and setting off fireworks are some common examples of ways in which burns occur. Thermal burns can also result from kitchen accidents, house or office fires, car accidents or physical abuse. Although it’s less common, exposure to extreme cold can also cause thermal burns.
Electrical burns result from contact with flowing electrical current. Household current, high-voltage transmission lines and lightning are sources of electrical burns. Internal injury is often considerably greater than is apparent externally.
Chemical burns most commonly result from contact (skin contact or inhalation) with a caustic agent, such as an acid, an alkali or a vesicant.
The most common radiation burn is sunburn, which follows excessive exposure to the sun. Almost all other burns due to radiation exposure occur as a result of radiation treatment or in specific industries that use or process radioactive materials.
Conduct your initial assessment as soon as possible after the burn occurs. First, assess the patient’s ABCs. Then determine the patient’s level of consciousness and mobility. Next, assess the burn, including its size, depth and complexity.
Determine burn size as part of your initial assessment. Typically, burn size is expressed as a percentage of total body surface area (TBSA). The Rule of Nines and the Lund–Browder Classification provide standardised and quick estimates of the percentage of TBSA affected.
To remember the proper sequence for the initial assessment of a burns patient, remember your ABCs and add D and E.
Airway – Assess the patient’s airway, remove any obstruction and treat any obstructive condition.
Breathing – Observe the motion of the patient’s chest. Auscultate the depth, rate and characteristics of the patient’s breathing.
Circulation – Palpate the patient’s pulse at the carotid artery and then at the distal pulse points in the wrist, posterior tibial area and foot. Loss of distal pulse may indicate shock or constriction of an extremity.
Disability – Assess the patient’s level of consciousness and ability to function before attempting to move or transfer them.
Expose – Remove burned clothing from burned areas of the patient’s body and thoroughly examine the skin beneath.
Last week in my personal blog I reflected on humility as defined by James Ryle:
God given self-assurance that eliminates the need to prove to others the worth of who you are and the rightness of what you do.
Ryle suggests, from 1 Peter 5:5-7, that central to humbling ourselves is throwing our cares on to God. Every concern, care and fear being hurled on to God who is faithful and powerful enough to handle them. When we know that we are loved by Him no matter what and that He is in control no matter what, then we remove the need to prove ourselves or protect ourselves. We become humble – secure enough to allow God to be in control and to serve others. Once our eyes are lifted from ourselves we are able to see others to love and serve them.
Just before writing the last post I was reading an article about the report by Robert Francis QC on the appalling treatment of patients at Stafford Hospital. One of the recurring comments made by many different people is that the pressure of targets and incentives increasingly displaces focus on compassion and patient care. When doctors, nurses and managers alike are bombarded with ever increasing and regularly changes hoops to jump through and targets to meet, no wonder their attention and efforts are dragged from patient care.
I’ve seen something of the effects of this in a family member who for many years worked as a Health Visitor. In their decades of service they saw an ever increasing and ever changing string of targets and goals alongside cost cutting moves that stripped resources and personnel. Their desire to be compassionate and offer the best care possible became more and more stressful until it finally proved too much. She recently changed jobs.
Now I’m not trying to attack the NHS and I am well aware that so many people receive great care. But this is not a new concern that is being bandied around with fresh vigour in the light of Stafford Hospital. What struck me is that it demonstrates on an institutional level what also seems true at a personal level. Namely, that when we are forced to operate from a place of insecurity we begin to miss the most important things. NHS services have to meet targets to receive funding to simply keep operating – there will be no patient care if there is no hospital. Oftentimes, especially as a leader, we can live with a sense that, unless we meet expectations or make people like us or recognise our worth, then we’ll have no influence to do any of the things we know we are called to do.
The secret of personal humility is to recognise that we are already loved by our Father before we even move our finger; to recognise that He is control and we can throw every care on Him. A person who can live from that place of security finds, free from the need to prove themselves or their actions, can begin to simply do what they are made and called to do. They are no longer pulled in different directions by a multiplicity of cares. What about an institution?
It strikes me that a similar solution is needed for the NHS. Is there a way to give security for doctors, nurses and caring professionals so that they are able to do what they are called to do without constantly watching their back? Obviously there is a need for accountability for the safety of patients and to ensure a good standard of care, but the constant need to prove worth and achievement cannot be helpful for those who are called to compassionate care.
I’m not a healthcare professional. I don’t know exactly what this would look like. But I recognise in the diagnosis of struggles in the NHS, God’s diagnosis of struggles in many people’s lives. The way He designed us to live with Him is often a good basis to begin to imagine a new way for every level of society to function.
So, my question is this: what would a humble NHS look like? To whom could a National Health Service throw it’s concerns and cares?
This month’s case is by David R Bell PhD, co-author of Medical Physiology: Principles for Clinical Medicine, 3e (ISBN: 9781451110395) For more information, or to purchase your copy, visit: http://tiny.cc/Rhoades4e, with 15% off using the discount code: MEDUCATION.
The case below is followed by a quiz question, allowing you a choice of diagnoses. Select the one letter section that best describes the patient’s condition.
A 28-year old woman has an unremarkable pregnancy through her first 28 weeks of gestation, with normal weight gain and no serious complications. She has no previous history of diabetes, hypertension of other systemic disease before or during her current pregnancy. During her 30-week checkup, her blood pressure measures 128/85, and she complains about feeling slightly more “bloated” than usual with swelling in her legs that seems to get more uncomfortable as the day goes on. Her obsterician recommends that she get more bed rest, stay off her feet as much as possible and return for evaluation in one week.
At the one-week follow-up, the patient presents with noticable”puffiness” in her face, and a blood pressure of 145/95. She complains she has been developing headaches, sporadic blurred vision, right-sided discomfort and some shortness of breath. She has gained more than 10 lb (4.5kg) in the past week. A urinalysis on the patient revelas no glucose but a 3+ reading for protein. Her obstetrician decides to admit her immediately to a local tertiary care hospital for further evaluation. Over the next 24 hours, the patient’s urine output is recorded as 500mL and contains 6.8 grams of protein.
Her plasma albumin level is 3.1 g/dl, hemacrit 48%, indirect bilirubin 1.5mg/dl and blood platelets=77000/uL, respectively. Her blood pressure is now 190/100.
It is decided to try to deliver the foetus. The expelled placenta is small and shows signs of widespread ischmic damage. Within a week of delivery, the mother’s blood pressure returns to normal, and her oedema subsides. One month later, the mother shows no ill effects of thos later-term syndrome.
What is the clinical diagnosis of this patient’s condition and its underlying pathophysiology?
A. Gestational Hypertension
C. Gestational Diabetes
D. Compression of the Inferior Vena Cava
The correct answer is "B. Preeclampsia".
The patient’s symptoms and laboratory findings are consistent with a diagnosis of Preeclampsia, which is a condition occurring in some pregnancies that causes life-threatening organ and whole body regulatory malfunctions. The patient’s negative urine glucose is inconsistent with gestational diabetes. Gestational hypertension or vena caval compression cannot explain all of the patient findings. The patient has three major abnormal findings- generalised oedema, hypertension and proteinuria which are all common in preeclampsia. Although sequalae of a normal pregnancy can include water and salt retention, bloating, modest hypertension and leg swelling (secondary to capillary fluid loss from increased lower limb capillary hydrostatic pressure due to compression of the inferior vena cava by the growing foetus/uterus), oedema in the head and upper extremities, a rapid 10 pound weight gain and shortness of breath suggests a generalized and serious oedematous state. The patient did not have hypertension before or within 20 weeks gestation (primary hypertension) and did not develop hypertension after the 20th week of pregnancy with no other abnormal findings (gestational hypertension). Hypertension with proteinuria occurring beyond the 20th week of pregnancy however is a hallmark of preeclampsia. In addition, the patient has hemolysis (elevated bilirubin and LDH levels), elevated liver enzyme levels and thrombocytopenia. This is called the HELLP syndrome (HELLP = Hemolysis, Elevated Liver enzymes and Low Platelets.), and is considered evidence of serious patient deterioration in preeclampsia.
A urine output of 500 ml in 24 hours is 1/2 to 1/4 of normal output in a hydrated female and indicates renal insufficiency. Protein should never be found in the urine and indicates loss of capillaries integrity in glomeruli which normally are not permeable to proteins. The patient has substantial 24 urine protein loss and hypoalbuminemia. However, generally plasma albumin levels must drop below 2.5 gm/dl to decrease plasma oncotic pressure enough to cause general oedema. The patient’s total urinary protein loss was insufficient in this regard. Capillary hyperpermeability occurs with preeclampsia and, along with hypertension, could facilitate capillary water efflux and generalized oedema. However myogenic constriction of pre-capillary arterioles could reduce the effect of high blood pressure on capillary water efflux. An early increase in hematocrit in this patient suggests hemoconcentration which could be caused by capillary fluid loss but the patient’s value of 48 is unremarkable and of little diagnostic value because increased hematocrit occurs in both preeclampsia and normal pregnancy.
PGI2, PGE2 and NO, produced during normal pregnancy, cause vasorelaxation and luminal expansion of uterine arteries, which supports placental blood flow and development. Current theory suggests that over production of endothelin, thromboxane and oxygen radicals in preeclampsia antagonize vasorelaxation while stimulating platelet aggregation, microthrombi formation and endothelial destruction. These could cause oedema, hypertension, renal/hepatic deterioration and placental ischemia with release of vasotoxic factors. The patient’s right-sided pain is consistent with liver pathology (secondary to hepatic DIC or oedematous distention).
Severe hypertension in preeclampsia can lead to maternal end organ damage, stroke, and death. Oedematous distension of the liver can cause hepatic rupture and internal hemorrhagic shock. Having this patient carry the baby to term markedly risks the life of the mother and is not considered current acceptable clinical practice. Delivery of the foetus and termination of the pregnancy is the only certain way to end preeclampsia.
This case is by David R Bell PhD, co-author of Medical Physiology: Principles for Clinical Medicine, 3e (ISBN: 9781451110395)
For more information, or to purchase your copy, visit: http://tiny.cc/Rhoades4e.
Save 15% (and get free P&P) on this, and a whole host of other LWW titles at (lww.co.uk)[http://lww.co.uk] when you use the code MEDUCATION when you check out!
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