(临床诊断学) 仁济临床医学院诊断学教研室 An Introduction to Clinical Diagnostics



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上海交通大学医学院诊断学双语教材


Clinical Diagnostics
(临床诊断学)

仁济临床医学院诊断学教研室


An Introduction to Clinical Diagnostics

After you finish your premedical courses, you are now going to touch patients. The clinical diagnosis serves as a bridge between premedical and clinical medicine. It includes physical diagnosis, Laboratory diagnosis and some instrumental examination. Formerly these are taught separately but now our country they are combined to form one course, which is now called clinical diagnosis.

The medical students are the physicians of tomorrow, and as such, you need information from every source to unravel the mystery of the patients’ illness. Physical diagnosis deals with such information through the two most fundamental skills, the interrogation and physical examination.

Interrogation means to get the history in detail of a patient’s illness and the best way as to let the patient tell his story in his own. As some crucial points might be overlooked by the patients, you will ask many searching questions to make the history complete and more informative.

Occasionally a patient will not or cannot give a straight story, you may interrogate his (her)family members or friends to get more information date.

The next step is then to do a physical examination. The body of the patient will be examined meticulously in every way possible by you, using all of your five senses. A physical examination usually includes inspection, palpation, percussion, and auscultation. Here our ancient doctors had given great contributions. Almost two thousand years ago they had developed inspection, interrogation, smell and pulse palpation to make diagnosis and develop many syndromes which are still useful clinically today. After that you can make a preliminary analysis, correlating the history with positive physical signs, determining the organs involved and even set down a preliminary diagnosis, which we usually call it an impression but not a definite diagnosis. A definite diagnosis will be made with the help of other special investigative aids such as laboratory test, X ray films, EKG, endoscopy, ultrasonic imaging, CT scanning etc, to add further clues or evidences to the first impression obtained from physical diagnosis. Among them, only laboratory diagnosis and some instrumental examinations are included in the course of clinical diagnosis as other aids are too much specialistic and are usually taught separately.

Laboratory diagnosis is a science dealing with various kinds of laboratory examinations and tests. As laboratory diagnosis is so complex that it is impossible to apply all its contents to a single patient, you should select the proper ones according to the impression you obtain from physical diagnosis. The laboratory diagnosis usually contains two parts, the routine examination and the special tests. The routine examinations include blood, urine and stool routine examinations and the special tests usually direct to certain special organs.

The above are the general ways you will approach a patient when you go to the ward. In fact this is a kind of bedside medicine. You should study hard and try to master the technic. By this way you will understand what is health and what is disease. By this way you will learn the procedures to do a clinical analysis which should be fitting to dialectic materialism, that is, in an objective way. Further, you should always keep in mind you are dealing with the diseased man but not the disease, so you should give sympathy to the patient, and have a lofty mind of serving the people heart and soul.

Part I
Symptoms


Chapter 1 Fever

The core body temperature is kept constant (36.3-37.2o). Under normal circumstances, it is tightly regulated, with circadian variations over a range that usually does not exceed 1oC and a mean value of 37oC (the normal “set point”). Fever is defined as an elevation of core body temperature above the normal range.


Pathogenesis

It is important to realize that fever is not equivalent to an elevated core temperature but to an elevated set-point. The neuropathys responsible for thermoregulation originate in the hypothalamus. A local sensing mechanism exists wherein the temperature of blood is coupled to the development of autonomic discharge.

Two types of pyrogen: exogenous pyrogen and endogenous pyrogen


  1. Exogenous pyrogen: various microorganisms (such as endotoxin), mostly are polysaccharides, can cause muscle contraction and rigor.

  2. Endogenous: polymorphonuclear myelocytes and monocytes, activated by exogenous pyrogen, synthesize cytokines, which cause liberation of PGE from hypothalamus. The PGE is believed to reset the hypothalamic thermoregulatory center by prompting an elevation in core body temperature.

Etiology and classification



  1. Infective fever: After infection, metabolites from organism or pyrogen from WBC cause fever.

  2. Non-infective fever:

1). Absorption of necrotic substances: injury; ischemic necrosis; cell necrosis

2). Allergy

3). Endocrine and metabolic disturbances: hyperthyroidism and dehydration

4). Decreased elimination of heat from skin: heat failure

5). Dysfunction of central heat regulation:

a: Physical, as heat stroke;

b: chemical , as barbiturate poisoning;

c: Mechanical, as cerebral hemorrhage.

6). Dysfunction of vegetative nervous system; as the cases of sympathetic overactivity.

Clinical manifestations:


  1. The grade of fever

Low grade fever: 37.3~38oC

Moderate fever: 38~39oC

High fever: 39.1~41oC

Hyperthermia fever: over 41oC



  1. The clinical course and character of fever

The clinical courses of fever are consisted of the following three steps

1). Onset of fever

a: Sudden onset: fever rises within few hours, as pneumonia, up to 39~40oC

b: Gradual onset: fever rises gradually for few days, as typhoid

2). Persistence of fever: may be a: continued

b: remittent

c: intermittent

d: recurrent

e: undulant

f: irregular type

3). Subsidence of fever: may be subside by crisis or lysis
Associated symptoms


  1. Chills or rigor: as in septicemia and any acute infections

  2. Congestion of conjunctiva: as in hemorrhagic fever

  3. Herpes simplex: caused by herpes virus, frequently seen in cases of lobar pneumonia

  4. Bleeding tendency: in severe infection as hepatitis and blood dyscrasia as leukemia

  5. Lymph node enlargement: in cases of lymphoma, of metastasis of cancer

  6. Enlargement of liver and spleen: in cases of hepatitis, leukemia

  7. Arthralgia: in gout, rheumtic disease

  8. Rash: drug rash, measles

9. Coma: in barbiturate poisoning, cerebral hemorrhage

Diagnostic points

Acute fever of less than two weeks are most of infectious origin, with an inflammatory focus. Thus, either history or physical examination would show some suggestive points about the cause of fever.

Chapter 2 Pain
Pain is one of the common symptoms for which the physician is consulted. Proper evaluation of pain depends largely upon knowledge of the various qualities of pain, the significance of referred pain.
Pathological physiology

During injury of tissue, proteolytic enzymes are released which act on gamma globulin to liberate irritating substances that stimulate nerve endings. Bradykinins, serotonin, acetylchonie, 5-hydroxytypamine, histamine, prostaglandins, and other similar polypeptides or acid metabolites cause pain by irritating the nerve endings, from which the sensation is sent through posterior root of spinal cord, mostly cross to other side, through spinothalamic tract, (lateral) medulla pons, and internal capsule, spread diffusely into parietal and frontal lobe. The pain sensation is in segmental distribution, as anterior part of head is through trigeminal, the thorax is through first to fourth thoracic nerve, and upper abdomen the 6th-8th thoracic nerve.

Different organs may respond to different stimuli. Integumentary stimuli, at lowest level of intensity, evoke sensations of touch, pressure, warmth, cold or tickle. When noxious stimuli increased to the point approaching tissue destruction, pain is added. The stimuli which skin is sensitive may not be true in case of GI system, which is more sensitive to inflammation, ischemia, traction, spasm, while less to cutting, needing and burn. The heart is sensitive to acute ischemia. The joint to hypertonic saline, less to cutting.

There are two types of primary afferent nociceptors (pain receptors).



  1. C fiber: 2-4μm in diameter, conducts slowly and causes a dull pain, as from heart and viscera.
  2. A-delta fiber: 6-8μm in diameter, as from skin, refers pain from pericardium.


The referred pain is due to diseased internal organ, sending pain impulse through spinal cord, which reflects the impulse to corresponding segment of integument, coronary ischemic pain usually radiates to medial side of arm and fingers, which were supplied by 6th –8th cervical, (or T1- 2) over the left side.
Clinical characteristics

  1. Character of pain: spastic pain usually intermittent, and inflammatory persisting.

  2. Localization of pain: usually in the diseased part, sometimes it may be referred, as appendicitis with pain over epigastrium in early stage.

  3. Quality and intensity of pain: The pain of a peptic ulcer may be “gnawing”, “burning”. Anginal pain showed precordial distress or pain of dull, heavy quality. If intensity of pain is getting worse, it means that the disease process is going on. However, the severity, duration, frequency and special times of occurrence of pain are also important.

  4. Referred pain: The diffuse pain arising from deep somatic or visceral structures tends to be projected to a more superficial region with the same segmental innervation ---- so called referred pain. Pain of coronary insufficiency may be felt along the inner aspect of the arm or in the left interscapular region

  5. Aggravating and relieving factors: Anginal pain may be provoked by exertion, cold, emotional upset and relieved by rest or nitroglycerine. Ulcer pain is relieved by ingestion of food.

Headache
Nearly everyone is subject to headache from time to time. Although most often a benign condition, headache of new onset may be the earliest or the principal manifestation of serious systemic or intracranial disease and therefore requires thorough and systematic evaluation.

[Causes]
  1. Intracranial diseases


  1. Infection: Meningitis, Encephalitis, Brain Abscess, etc.

  2. Vascular Disease: Acute Subarachnoid Hmorrhage, Cerebral Hemorrhage, Cerebral Embolism, Cerebral Thrombosis, Hypertensive Encephalopathy, Arterial Venous Malformation, etc.

  3. Intracranial Mass: Primary Brain Tumor, Metastatic Brain Tumor, Intra-cranial Parasitic Infection, etc.

  4. Trauma: Cerebral Concussion, Cerebral Contusion and Laceration, Subdural Hematoma, Epidural Hematoma, Intra-cerebral Hematoma, etc.

  5. Others: Migraine, Cluster Headache, etc.

  1. Extracranial diseases

  1. Skull disease: Craniosynostosis, etc.

  2. Cervical Spine disease: Craniovertebral Junction Disease, such as, Chiari Malformation, etc.

  3. Neuralgia: Trigeminal Neuralgia, Glossopharyngeal Neuralgia, etc.

  4. Ocular disorders, such as, Glaucoma, Acute Iritis; dental disease, or sinusitis.

  1. Systematic disease:

  1. Acute infection: Influenza, typhoid, pneumonia or other fever diseases.

  2. Cardiac vascular disease: Hypertension, Heart Failure.

  3. Toxication: chemical or drug toxication.

  4. Others: Hypoglycemia, Anemia, Heat Stroke, SLE, etc.

  1. Hysteric Headache

[Mechanism]

Headache is caused by traction, displacement, inflammation, vascular spasm, or distention of the pain-sensitive structures in the head or neck. Isolated involvement of the bony skull, most of the dura, or most regions of grain parenchyma does not produce pain.

The pain sensitive structures within the cranial vault include venous sinuses, the anterior and middle meningeal arteries, the dura at the skull base, the trigeminal, glossopharyngeal, and vagus nerves, the proximal portions of the internal carotid artery and its branches near the Circle of Willis, and the sensory nuclei of the thalamus.

Extracranial pain sensitive structures include the periosteum of the skull, the skin, the subcutaneous tissues, muscles, and arteries, the neck muscles, the second and third cervical nerves, the eyes, ears, teeth, sinuses, and oropharynx, and the mucous membranes of the nasal cavity.


[Clinical Features]


  1. Acute Headache: Headaches that are new in onset and clearly different from any the patient has experienced previously are commonly a symptom of serious illness and therefore demand prompt evaluation.

  2. Subacute Headaches: Subacute headaches occur over a period of weeks to months. Such headaches may also signify serious medical disorders, especially when the pain is progressive or when it develops in elderly patients.

  3. Chronic Headaches: Headaches that have occurred for years usually have a benign cause.

  4. Characteristics of Pain: Headache is most often described as throbbing; a dull, steady ache; or a jabbing, lancinating pain. Pulsating, throbbing pain is frequently ascribed to migraine. A steady sensation of tightness or pressure is commonly seen with tension headache. The pain produced by intracranial mass lesions is typically dull and steady. It is important to remember that the character of the pain does not provide a reliable etiologic guide.

  5. Location of Pain:

Unilateral headache is an invariable feature of cluster headache and most migraine attacks.

Ocular or retroocular headache suggests a primary ophthalmologic disorder such as glaucoma, optic nerve disease.

Paranasal pain localized to one or several of the sinuses.

Headache due to intracranial mass lesions may be focal, but will be bioccipital and bifrontal when the intracranial pressure becomes elevated.



  1. Associated Symptoms:

Fever or chills may indicate systemic infection or meningitis.

Visual disturbances suggest an ocular disorder, or an intracranial process involving the visual pathways.

Nausea and vomiting are common in migraine and can be seen in the course of mass lesions. Papilledema will be found when the intra-cranial pressure is increased.

[History Taking]


  1. It is important to know how the onset of the headache, its characteristic and whether there are any precipitating factors.

  2. If the headache is associated with vomiting, increased intracranial pressure must be excluded.


[Case]

A 35 yrs old man has experienced headache in the past several years. He described it as a “dull” headache. And his headache worsened in the past month.

During physical examination, severe papilledema was found.

A CT scan revealed a big brain tumor at sphenoid wing.



So, his headache was caused by this large tumor and his intra-cranial pressure is so high that papilledema was obvious.



Chest pain
Chest pain is usually related to diseases of the chest.



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