An Intricate Interplay

A CLINICAL PROBLEM-SOLVING article by Richard Moseley, from the Veterans Affairs Ann Arbor Healthcare System, Michigan
A 55-year-old man presented with sinus congestion, headaches, chills, mild nausea, fatigue, and a “foggy” sensation that had lasted approximately 1 week. He reported darker urine than usual and had noticed that his eyes were turning yellow. The patient's medical history was notable for hypertension and hyperlipidemia. He consumed one to two alcoholic drinks per night. His medications included baby aspirin, atenolol, hydrochlorothiazide, lovastatin, fexofenadine, fish oil, acidophilus, vitamin D, and calcium carbonate. Three and a half years previously, at routine physical examination, the patient was noted to have mildly elevated liver-enzyme levels. At the time of the patient's current presentation, the examination was notable for scleral icterus and a soft, nontender abdomen with the liver edge palpable less than one finger breadth below the costal margin. Laboratory results which were returned late on a Friday afternoon showed markedly elevated aminotransferase levels, with more modest elevations of the alkaline phosphatase and bilirubin levels. The patient was advised to come to the emergency department that evening for further evaluation. In contrast to the broad differential diagnosis for elevations in serum aminotransferase levels that are less than 5 times the upper limit of the normal range, the causes of severe aminotransferase elevations (>20 times the upper limit of the normal range) are more limited. [Original Article]

A Complex Cause of Pleuritic Chest Pain

A CLINICAL PROBLEM-SOLVING article by Lindsay King from Brigham and Women's Hospital, Boston.
A 33-year-old man presented to the emergency department with pain in the right side of his chest that started 5 days earlier. It originated near his right shoulder blade and radiated throughout his right chest. The pain was worse with deep inspiration and when he was lying down. He also noted mild swelling of his lower legs during the past several weeks. He had mild tachycardia and hypertension. The patient had a history of ulcerative colitis, which had been diagnosed 4 years earlier. He also reported that both his children had contracted streptococcal pharyngitis 1 month earlier.
The clinical evaluation should initially determine whether there is a potentially life-threatening cause of chest pain, including pulmonary embolus, acute coronary syndrome, aortic dissection, or tension pneumothorax. The patient's chest pain worsens with deep inspiration and recumbency, which suggests either a pleuritic cause or a musculoskeletal cause.
An interactive medical case associated with this article is available at NEJM.org [Original Article]

静脈血栓症、膜性腎症、原発性硬化性胆管炎、過敏性大腸症候群の織りなす事例。疫学の世界では、むしろ単一の原因が求められることは稀だが、いざ臨床の場にあると、単一原因を見つけてしまうと安堵して他の原因を見逃してしまうことは往々としてある。特に、医療に限らずカタストロフィは複合要因によって招かれることは肝に銘じておきたい。

A Missed Connection

A CLINICAL PROBLEM-SOLVING article by Prashant Bhave from Northwestern University, Chicago.
A 63-year-old woman presented to the emergency department with edema and red discoloration of the skin of her legs. The edema had first appeared almost 2 years earlier but had worsened markedly within the past week and now extended to her midabdomen. She was able to walk about half a block before stopping to catch her breath. She also reported orthopnea, paroxysmal nocturnal dyspnea, and occasional sharp chest pains while walking. She noted that she had gained weight and had mild leg pain but did not have fevers, chills, or night sweats.
The patient was born in El Salvador and immigrated to the United States when she was 45 years of age. She had a remote history of tuberculosis but did not recall any details of the treatment for it.
A history of tuberculosis could put this patient at risk for constrictive pericarditis. In addition, histoplasmosis, which is also seen in Central America, can cause constrictive pericarditis, as well as fibrosing mediastinitis; either condition could raise cardiac filling pressures.  Because the patient lived in Central America for most of her life, she is also at risk for Chagas' disease. (206 words / 82 sec = 150 wpm) [Original Article]

高拍出性心不全の鑑別診断がポイントです。貧血、甲状腺機能亢進症、脚気、SIRSの他に隠されたつながり、シャント（A-V fistula, Bony shunt, Cardiac shunt）の想起が必要です。

Simple and Complex

A CLINICAL PROBLEM-SOLVING article by Siyang Leng from University of Pittsburgh Medical Center, Pennsylvania.
A 43-year-old man presented to the emergency department with chest pain that had started 1 hour earlier and had awakened him from sleep. The pain was severe, substernal, burning, radiating to the left arm, and accompanied by nausea and vomiting.
On physical examination, he appeared to be in considerable distress, clutching his chest. Cardiac examination revealed a regular rhythm without extra heart sounds, no jugular venous distention, and no lower-extremity edema. The fasting serum glucose level was 192 mg per deciliter. An electrocardiogram showed an acute injury pattern in the anterolateral wall of the heart that was consistent with ST-segment elevation myocardial infarction (STEMI) in the territory of the left anterior descending coronary artery.
The patient underwent left-sided cardiac catheterization. Percutaneous coronary intervention of the left anterior descending artery was performed, and two drug-eluting stents were placed.
On recheck the day after the cardiac catheterization, the white-cell count was 13,800 per cubic millimeter, the hemoglobin level was 15.6 g per deciliter, and the platelet count was 610,000 per cubic millimeter. A peripheral-blood smear showed an increased number of platelets and occasional giant platelets.
This case illustrates that even a seemingly straightforward presentation of a common illness may involve a more complex underlying disorder, which, when recognized, changes the approach to the patient. [Original Article]

Further Reading

• Kardasz I, De Caterina R. Myocardial infarction with normal coronary arteries: a conundrum with multiple aetiologies and variable prognosis: an update. J Intern Med 2007;261:330-348

AudacityでClinical Problem-Solvingを抽出

Audacityが、どういうソフトかということは、Wikipediaを参照してください。ここでは、audiosummaryからClinical Problem-Solvingを切り出す方法についてメモしておく。

1. 「ファイル→取り込み...→オーディオの取り込み...」(Ctrl + Shift +I)でaudiosummaryの音声ファイルを読み込む。
2. 「編集→選択→すべて」(Ctrl + A)でポッドキャスト全体を選択。
3. 「解析→Silence Finder...」で無音部にラベルする。(設定は、無音閾値26-dB、無音持続時間1.5秒、ラベル位置0.7秒とした。)
* 「編集→設定...」(Ctrl + P)でSilence Finderのキーボードショートカットを"Ctrl + Shift + E"とでも設定しておくと便利。
4. ラベルを参考にClinical Problem-Solvingの前後を「編集→オーディオの削除→削除」(Ctrl + K)で削除する。（後を削除してから前を削除すると分かりやすい。）
5. 「ファイル→書き出し」でファイル名をつけて保存する。
* 「編集→設定...」(Ctrl + P)でSilence Finderのキーボードショートカットを"Ctrl + Shift + W"とでも設定しておくと便利。

肝心な部分は耳で確認し、手動での操作となるので間違うこともあり得る。Clinical Problem-Solvingはだいたい１，２分の長さなので、１、２MB程度の容量となる。保存する時にフェールセーフのために容量の確認をすることをお薦めする。

Clinical Problem-Solving

Jerome P Kassirer先生達がHospital Practice誌で始めたClinical Problem-Solvingは、CPCが法学のケースメソッドを医学教育に応用したものであるのに対し、より臨床の現場に即し、認知科学の成果を診断過程に応用したものである。認知科学の裾の広さは、ダニエル・カーネマンらがノーベル経済学賞を受賞したことからも窺い知ることができる。HP誌での連載の成果は、"Learning Clinical Reasoning"にまとめられ、Kassirer先生が1991年NEJM誌の編集長に就任した翌年の今日、NEJMでのClinical Problem-Solvingの連載が始まった。最近出版された"Learning Clinical Reasoning"第二版では、NEJM誌での連載の症例が付け加えられた。翻訳は、岩田健太郎教授が手掛けている。第二版の症例集の部分の目次とNEJM誌のオリジナル記事へのリンクを下に掲げておく。

Diagnostic Hypothesis Generation

• Case 1 Generation of Diagnostic Hypotheses 

• Case 2 Hypothesis Triggering by an Expert 

• Case 3 A Diagnostic Coup 

• Case 4 A Quick and Accurate Solution 

• Case 5 Better Late Than Never

• Case 6 A Hit After a Miss 

• Case 7 The Critical Role of Context in the Diagnostic Process 

• Case 8 A Masked Marauder

• Case 9 A Serious Lack of Focus 

Refinement of Diagnostic Hypotheses

• Case10 What is a Differential Diagnosis? 

• Case11 An Orderly, Sequential Approach 

• Case12 Weak Reasoning: Diagnosis by Drug Reaction

• Case13 Narrowing Down the Diagnostic Options 

• Case14 A Picture is Worth a Thousand Words 

• Case15 Strategies of Information Gathering 

• Case16 A Fatal Flaw in Sutton's Law 

• Case17 How to Disregard Red Herrings 

• Case18 Discrimination: The Problem of Look-Alikes 

• Case19 Location, Location, Location 

Use and Interpretation of Diagnostic Tests

• Case20 Interpreting a Negative Test Result 

• Case21 Diagnosis and the Risks of the Primrose 

• Case22 Path Searching for a Pony 

• Case23 Interpreting Hoofbeats: Can Bayes Help Clear the Haze?

• Case24 Short-Circuiting the Diagnostic Process 

• Case25 The Bypass on the Way to the Bypass 

• Case26 It is What You Believe That Counts 

• Case27 Renal Rescue by Reverend Bayes 

• Case28 A Diagnostic Fluke 

• Case29 Surprise! 

• Case30 Tripping Over Technology 

• Case31 The Probability of a Probability 

Causal Reasoning

• Case32 Judging Causality 

• Case33 Post Hoc, Ergo Propter Hoc 

• Case34 The Case for Causal Reasoning 

• Case35 The Tricky Task of Attributing Causation 

• Case36 The Right Answer for the Wrong Reason 

Diagnostic Verification

• Case37 A Point-By-Point Dissection of Clinical Reasoning 

• Case38 Leaving No Stone Unturned 

• Case39 Verification 

• Case40 A Meticulous Approach 

• Case41 A Diagnostic Quandary 

• Case42 Diagnosis by Fiat 

• Case43 Iron Pyrite and Diagnostic Confirmation 

Therapeutic Decision Making

• Case44 The Surgeon Opts to Operate: Why? 

• Case45 Treat or Keep Testing? 

• Case46 Watch and Wait, or Operate? 

• Case47 An Apple or an Orange? 

Examining Evidence

• Case48 A Difficult Tradeoff  

• Case49 Making Judgments When the Evidence is Not 

• Case50 Definitive Using and Citing Published Evidence 

• Case51 A Little Math Makes the Medicine Go Down

• Case52 A Rewarding Pursuit of Certainty

• Case53 Treating Before Knowing

Cognitive Errors

• Case54 A Defective Detective 

• Case55 Remedies for Faulty Hypothesis Generation

• Case56 A Disaster Averted 

• Case57 Derailed by the Availability Heuristic 

• Case58 Wrong Diagnosis, Wrong Tests, Wrong 

• Case59 Treatment Reconsidering Failures of Therapy 

• Case60 The Cheetah and the Snail 

• Case61 A Collection of Cognitive Diagnostic 

Errors Some Cognitive Concepts

• Case62 A Message about Methods 

• Case63 Memory: How We Overcome its Limitations 

• Case64 Diagnosis and the Structure of Memory;  Disease Polymorphism and Mental Models

• Case65 Intuitive and Inspirational, or Inductive and Incremental? 

• Case66 Knowledge and Clinical Expertise

Learning Clinical Problem Solving

• Case67 Learning Clinical Reasoning from Examples 

• Case68 Making a Silk Purse out of a Sow's Ear 

• Case69 Optimizing Case Discussions

今年の抱負

1. NEJMのポッドキャストのClinical Problem-SolvingのDictation、Shadowing、Reproductionを日々行う。
2. 上記を通じて４月までにコーパスを作成する。
3. 同様のことをCabot Casesで継続する。
4. Cabot Cases Corpusを12月までに作成する。
5. 機械学習の手法を使って症例提示英語のリスニングの速習に関し何らかの成果を抽出する。(具体的には、上記素材の英語のリスニングを３ヶ月で可能にする合理的方法論)

５の機械学習に関しては、右のシロエリハゲワシが表紙のオライリー本がRを使って実践的に学べる模様。ちょうど12章立てなので１ヶ月に１章ずつ、英文・和文両方でじっくり読み進めていくつもり。著者自身によるコードや補足資料がGithubで公開されています。それにしても、英文の電子版が1,485円だから、出版のタイムラグやコスパを考えると、英語のSpeed Readingもぜひ身につけたいスキルの１つ、Kindleでの英語は老眼になりかけた目にも優しいですし…
　もう一冊、本職関連で、「サパイラ(Sapira's Art and Science of Bedside Diagnosis )」を英語、日本語双方でじっくり読んでおきたい。

今年の心構え

• Purpose, Prior Planning, Passion, Patience and Persistence Prevent Piss Poor Performance. 
• Concentration in Core Competance.