190 - Empyema necessitans

*I have always been a fan of medical nomenclature, but iam not sure about this one.
*Medical words usually give away most of the information by their names itself, but this one is tricky.

*Empyema necessitans is a condition where the pus in the thorax (empyema - developed due to some infectious process of lung and pleura) leaks into the soft tissues of the thorax, after burrowing through the parietal pleura. (the name doesn't give away anything, does it?).

*The word empyema implies that the pus is contained in the pleural cavity.

*It may either occur due to the virulence of the organism or may be facilitated by previous thoracic surgery (e.g thoracotomy) or trauma allowing infection to track through.

*It occurs commonly to subcutaneous tissues of the chestwall, but can also spread to involve other sites such as the esophageal, breast, retroperitoneal, peritoneal, pericardial, para vertebral regions.
*The resultant subcutaneous abscess may eventually rupture through the skin.

* Causative organisms are Mycobacterium tuberculosis - thought to be commonest cause, Actinomyces spp - considered second commonest cause,  Blastomycosis spp, Aspergillus spp, Mucormycosis spp.

*Radiographic features : CT chest Best at assessing extent of infection out of the thoracic cavity. will classically show an empyema (often relatively well demarctated collection) with extension through the chest wall into an extra-thoracic compartment. Accompanying rib destruction may be present.

*Differential diagnosis : General imaging differential considerations include malignant pleural based mass - e.g. mesothelioma : different clinical context and will have more solid components, trans-diaphragmatic spread of intra abdominal infection / collection

189 - Situations that can mimic death

*Hypothermia
*Drug overdose (drugs like opioids, tricyclic antidepressants, barbiturates, alcohol and anaesthetic agents)
*Near drowning, cold water immersion
*Severe hypoglycemia
*Severe hepatic encephalopathy
*Myxedema coma
*Severe catatonic state

------

*These conditions are important and need to be remembered when you are confirming death of a patient. It is also important for everybody to know the PROTOCOL FOR CONFIRMATION OF DEATH :

1. Feel for a major (carotid or femoral) pulse for atleast 1 minute.
2. Listen for heart sounds over the cardiac apex for at least 1 minute.
3. While you are doing this, watch the chest wall for any movement.
4. Listen to the chest for breath sounds for 3 minutes.
5. Watch for any spontaneous movement during your examination.
6. Check there is no motor response to supra-orbital examination.
7. Simultaneously retract both eyelids, shine a bright light into each eye in turn and check that both pupils are fixed and unreactive.
8. Check the corneal reflexes, which should be absent. (The video below shows how you elicit a CORNEAL REFLEX)



*In certain situations, additional investigations may be available and confirmatory: for example, an ECG monitor trace showing asystole, absence of pulsatile flow from an intra-arterial line or absence of contractile motion on echocardiography.

188 - Digitalis toxicity

*Reduced tolerance of digoxin may be seen in (factors predisposing to digitalis toxicity) :
 - Advanced age
- Acute Myocardial Infarction/ Ischemia/ Hypoxemia
- Magnesium depletion (hypomagnesemia)

- Hypercalcemia (Calcium synergises with digitalis and precipitates its toxicity)
- Hypothyroidism (Both hyperthyroidism and hypothyroidism enhance digitalis toxicity. Thyrotoxicosis patients are more prone to develop digitalis arrhythmias and Myxedema enhances responsiveness to digitalis. Myxedema patients eliminate digoxin more slowly)
- Renal insufficiency (Digoxin is mainly excreted by kidneys)

- Electrical cardioversion 

* Digitalis toxicity causes hyperkalemia, but hypokalemia enhances digitalis toxicity (by increasing its binding to Na+/K+ ATPase.

*The administration of the following drugs raises the serum concentration of digoxin :
- Quinidine
- Verapamil
- Procainamide
- Amiodarone

*MANAGEMENT OF DIGITALIS OVERDOSE :

- Withdrawl of the drug
- Potassium (administer cautiously and by oral route whenever possible if hypokalemia is present. Potassium must not be employed in the presence of A-V block or hyperkalemia.
- Phenytoin/Beta blocker or Lidocaine : Lidocaine is effective in treatment of digitalis induced ventricular tachyarrythmias.
- Cardiac pacemaker : may be required in digitalis induced A-V block.
- Electrical conversion : may be life saving in digitalis induced ventricular fibrillation 
- FAB fragments/ digitalis antibodies : are potentially life saving in severe intoxication 
- Hemodialysis is not useful in digoxin toxicity .

(Other conditions where hemodialysis is ineffective is Digoxin poisoning, Kerosene poisoning, Benzodiazepine poisoning and Organophosphate poisoning)

(Remember that Digoxin and Digitoxin are two different drugs, both derived from digitalis, But digitoxin is mainly excreted by liver and digoxin is mainly excreted by kidneys. Hence digoxin dosage need not be adjusted in liver failure and digitoxin dosage need not be adjusted in renal failure)

*The most lipid soluble cardiac glycoside is Digitoxin.
*The most rapidly absorbed oral glycoside is digitoxin.

187 - Metabolic syndrome - Clinical identification

Clinical Identification of the Metabolic Syndrome—Any Three Risk Factors

Risk Factor Defining Level Abdominal obesitya   Men (waist circumference)b >102 cm (>40 in.)   Women >88 cm (>35 in.) Triglycerides >1.7 mmol/L (>150 mg/dL) HDL cholesterol   Men <1.0 mmol/L (<40 mg/dL)   Women <1.3 mmol/L (<50 mg/dL) Blood pressure greater than or equal to 130/greater than or equal to 85 mmHg Fasting glucose >6.1 mmol/L (>110 mg/dL)

aOverweight and obesity are associated with insulin resistance and the metabolic syndrome. However, the presence of abdominal obesity is more highly correlated with the metabolic risk factors than is an elevated body-mass index (BMI). Therefore, the simple measure of waist circumference is recommended to identify the BMI component of the metabolic syndrome. bSome male patients can develop multiple metabolic risk factors when the waist circumference is only marginally increased, e.g., 94–102 cm (37–39 in.). Such patients may have a strong genetic contribution to insulin resistance. They should benefit from life-style changes, similarly to men with categorical increases in waist circumference.

186 - Pneumonia Severity Index (PSI) score or PORT score

*The decision to hospitalize a patient with CAP must take into consideration diminishing health care resources and rising costs of treatment. The cost of inpatient management exceeds that of outpatient treatment by a factor of 20 and accounts for most CAP-related expenditures.

*Certain patients clearly can be managed at home, and others clearly require treatment in the hospital, but the choice is sometimes difficult. Tools that objectively assess the risk of adverse outcomes, including severe illness and death, may minimize unnecessary hospital admissions and help to identify patients who will benefit from hospital care.

*There are currently two sets of criteria: the Pneumonia Severity Index (PSI), a prognostic model used to identify patients at low risk of dying; and the CURB-65 criteria, a severity-of-illness score.

*To determine the PSI, points are given for 20 variables, including age, coexisting illness, and abnormal physical and laboratory findings.

*On the basis of the resulting score, patients are assigned to one of five classes with the following mortality rates:

-class 1, 0.1%;

-class 2, 0.6%;

-class 3, 2.8%;

-class 4, 8.2%; and

-class 5, 29.2%.

*Clinical trials have demonstrated that routine use of the PSI results in lower admission rates for class 1 and class 2 patients. Patients in classes 4 and 5 should be admitted to the hospital, while those in class 3 should ideally be admitted to an observation unit until a further decision can be made.

*The CURB-65 criteria include five variables: 

1. Confusion (C); 

2. Urea >7 mmol/L (U); 

3. Respiratory rate greater than or equal to 30/min (R); 

4. Blood pressure, systolic less than or equal to 90 mmHg or diastolic less than or equal to 60 mmHg (B); and 

5. Age greater than or equal to 65 years (65). 

*Patients with a score of 0, among whom the 30-day mortality rate is 1.5%, can be treated outside the hospital.

*With a score of 2, the 30-day mortality rate is 9.2%, and patients should be admitted to the hospital.

*Among patients with scores of greater than or equal to 3, mortality rates are 22% overall; these patients may require admission to an ICU.

*At present, it is difficult to say which assessment tool is superior. The PSI is less practical in a busy emergency-room setting because of the need to assess 20 variables. While the CURB-65 criteria are easily remembered, they have not been studied as extensively. Whichever system is used, these objective criteria must always be tempered by careful consideration of factors relevant to individual patients, including the ability to comply reliably with an oral antibiotic regimen and the resources available to the patient outside the hospital.

185 - Drug induced Lupus

*This is a syndrome of positive ANA associated with symptoms such as fever, malaise, arthritis or intense arthralgias/myalgias, serositis, and/or rash.

*The syndrome appears during therapy with certain medications and biologic agents, is predominant in Caucasians, has less female predilection than SLE, rarely involves kidneys or brain, is rarely associated with anti-dsDNA, is commonly associated with antibodies to histones, and usually resolves over several weeks after discontinuation of the offending medication. 

*The list of substances that can induce lupus-like disease is long. Among the most frequent are the :

- Antiarrhythmics procainamide, disopyramide, and propafenone; 
- The antihypertensive hydralazine; several angiotensin-converting enzyme inhibitors and beta blockers; 
- The antithyroid propylthiouracil; 
- The antipsychotics chlorpromazine and lithium; 
- The anticonvulsants carbamazepine and phenytoin; 
- The antibiotics isoniazid, minocycline, and macrodantin; 
- The antirheumatic sulfasalazine; 
- The diuretic hydrochlorothiazide; 
- The antihyperlipidemics lovastatin and simvastatin; and 
- Interferons and TNF inhibitors. 

*ANA usually appears before symptoms; however, many of the medications mentioned above induce ANA in patients who never develop symptoms of drug-induced lupus.

*It is appropriate to test for ANA at the first hint of relevant symptoms and to use test results to help decide whether to withdraw the suspect agent.

184 - Effects of Physiological and Pharmacologic interventions on Heart Murmurs and sounds

Respiration Systolic murmurs due to TR or pulmonic blood flow through a normal or stenotic valve and diastolic murmurs of TS or PR generally increase with inspiration, as do right-sided S3 and S4. Left-sided murmurs and sounds usually are louder during expiration, as is the PES.

Valsalva maneuver Most murmurs decrease in length and intensity. Two exceptions are the systolic murmur of HCM, which usually becomes much louder, and that of MVP, which becomes longer and often louder. Following release of the Valsalva maneuver, right-sided murmurs tend to return to control intensity earlier than left-sided murmurs.

After VPB or AF Murmurs originating at normal or stenotic semilunar valves increase in the cardiac cycle following a VPB or in the cycle after a long cycle length in AF. By contrast, systolic murmurs due to AV valve regurgitation either do not change, diminish (papillary muscle dysfunction), or become shorter (MVP).

Positional changes With standing, most murmurs diminish, two exceptions being the murmur of HCM, which becomes louder, and that of MVP, which lengthens and often is intensified. With squatting, most murmurs become louder, but those of HCM and MVP usually soften and may disappear. Passive leg raising usually produces the same results.

Exercise Murmurs due to blood flow across normal or obstructed valves (e.g., PS, MS) become louder with both isotonic and submaximal isometric (handgrip) exercise. Murmurs of MR, VSD, and AR also increase with handgrip exercise. However, the murmur of HCM often decreases with near maximum handgrip exercise. Left-sided S4 and S3 are often accentuated by exercise, particularly when due to ischemic heart disease.

Note: TR, tricuspid regurgitation; TS, tricuspid stenosis; PR, pulmonic regurgitation; HCM, hypertrophic cardiomyopathy; MVP, mitral valve prolapse; PS, pulmonic stenosis; MS, mitral stenosis; MR, mitral regurgitation; PES, pulmonic ejection sound; VSD, ventricular septal defect; AR, aortic regurgitation; VPB, ventricular premature beat; AF, atrial fibrillation.

183 - First Heart Sound (S1)

*The first heart sound is otherwise called as S1.

*Its duration is 0.14 seconds.

*Its frequency is 25-45 Hz.

*Though S1 and S2, both are high pitched sounds, S1 has a lower frequency than S2. (50 Hz).

*The sound produced is a slightly prolonged "LUB".

*The cause of the first heart sound is the sudden closure of the mitral and tricuspid valves.

*The timing of the S1, is at the start of the ventricular systole.

*The first and second heart sounds, and the opening snaps are best heart with the diaphragm of the stethoscope, and low pitched sounds, such as the third and fourth heart sounds are best heard with the bell of the stethoscope.

*S3 and S4, can often not be heard with stethoscope (ear) and require phonocardiogram. S3 often and S4 sometimes can be recorded in phonocardiogram.

*CAUSES OF SOFT S1 :
1. Poor conductance of sound through chest wall. eg: Obesity, Ephysema, Pleural effusion and Pericardial effusion.
2. Decrease in rate of LV pressure development. eg: Myxoedema, Cardiomyopathy, Acute MI and MR.
3. PR interval and velocity of valve closure. eg: Prolonged PR interval - First degree heart block.
4. Mobility of the valve. eg: Severe calcification of the valve or reduced mobility of the valve - Long standing MS is associated with severe calcification of mitral valve and soft S1.

*CAUSES OF LOUD S1 :
1. Tachycardia : S1 is louder if diastole is shortened due to Tachycardia. eg: Anemia, anxiety and fever.
2. Increased AV flow due to high cardiac output. eg: AV fistula and thyrotoxicosis.
3. Increased AV flow due to left to right shunt. eg: ASD, PDA and other conditions.
4. Prolonged AV flow due to stenosis. eg: MS and TS.
5. Short PR interval (velocity of valve closure) - At short PR intervals, the mitral valve leaflets are maximally separated by atrial contraction. At the onset of LV systole, the mitral valve leaflets therefore close with a high velocity and with a large excursion resulting in loud S1.

*First Heart sound (M1,T1) is produced by the closure of the Mitral valves (M1) and Tricuspid valves (T1).

*The Mitral valves close slightly before the Tricuspid valves .

*This normal splitting (physiological splitting) cannot be detected by auscultation because both components are low pitched and separated by only 20-30 milliseconds.

*Therefore splitting of the first heart sound whenever audible, is considered pathological.

*CAUSES OF PATHOLOGICAL NORMAL SPLITTING OF S1 (T1 follows M1 after a long gap):
- RBBB (Right Bundle Branch Block)
- LV pacing
- Ectopic beats and idioventricular rhythms originating in left ventricle
- Ebstein's anamoly

*CAUSES OF PATHOLOGICAL REVERSE SPLITTING OF S1 (T1 precedes M1) :
- LBBB
- RV pacing
- Ectopic beats and idioventricular rhythms originating in right ventricle
- Severe MS and atrial myxoma

182 - Opportunistic infections in HIV

181 - Arteriographic abnormalities in Takayasu disease

Artery	Percent of Arteriographic  Abnormalities	Potential Clinical Manifestations
Subclavian	93	Arm claudication, Raynaud's phenomenon
Common carotid	58	Visual changes, syncope, transient  ischemic attacks, stroke
Abdominal aortaa	47	Abdominal pain, nausea, vomiting
Renal	38	Hypertension, renal failure
Aortic arch or root	35	Aortic insufficiency, congestive heart failure
Vertebral	35	Visual changes, dizziness
Coeliac axisa	18	Abdominal pain, nausea, vomiting
Superior mesenterica	18	Abdominal pain, nausea, vomiting
Iliac	17	Leg claudication
Pulmonary	10–40	Atypical chest pain, dyspnea
Coronary	<10	Chest pain, myocardial infarction

^aArteriographic lesions at these locations are usually asymptomatic but may potentially cause these symptoms.

182 - Chemical carcinogens - IARC group 1 (selected)

CHEMICAL CARCINOGEN	PREDOMINANT TUMOR TYPE
Aflatoxins	Liver cancer
Benzene	Leukemia
Cyclophosphamide	Bladder cancer, Leukemia
Diethyl stilbestrol (DES)	Vaginal and clear cell adenocarcinomas
Estrogen replacement therapy	Endometrial and breast cancers
Tamoxifen	Endometrial cancer
Tobacco products (smokeless)	Oral cancer
Nickel	Lung cancer
Cadmium	Lung cancer
Chromium (VI) compounds	Lung cancer
Beryllium	Lung cancer
Tobacco smoke	Lung cancer, Oral cancer, Pharyngeal cancer, Laryngeal cancer, esophageal cancer (squamous cell), pancreatic cancer, bladder cancer, Liver cancer, Renal cell carcinoma, Cervical cancer, Leukemia
Vinyl chloride	Angiosarcoma of liver, hepatocellular carcinoma, brain tumors, lung cancer, malignancies of lymphatic and hematopoietic system
Chlorambucil	Leukemia
Arsenic	Skin cancer
Benzidine	Bladder cancer
Coal tar	Skin cancer and scrotal cancer
Ethylene oxide	Leukemia and lymphoma
Chinese style salted fish	Nasopharyngeal carcinoma
TCDD (2,3,7,8-tetrachlorodibenzo -para-dioxin)	Soft tissue sarcoma

*IARC stands for International agency for Research on Cancer.

*Only tumor types for which causal relationships are established are listed here.

*Tamoxifen is shown to prevent contralateral breast cancer.

181 - Complement system pathways

180 - Dicrotic pulse

The dicrotic pulse has two palpable waves, one in the systole and one in diastole (Figure above). It usually denotes a very low stroke volume, particularly in patients with dilated cardiomyopathy.

A dicrotic pulse results from an accentuated dicrotic wave and tends to occur in patients with

*sepsis, 
*severe heart failure, 
*hypovolemic shock, 
*cardiac tamponade, and 
*aortic valve replacement.

179 - Pulsus Bisferiens

Pulsus bisferiens with both percussion and tidal waves occurring during systole. This type of carotid pulse contour is most frequently observed in patients with hemodynamically significant aortic regurgitation or combined aortic stenosis and regurgitation with dominant regurgitation. It is rarely appreciated at the bedside by palpation.

The bisferiens pulse, which has two systolic peaks (as shown in figure above), is characteristic of aortic regurgitation (with or without accompanying stenosis) and of hypertrophic cardiomyopathy .
In the latter condition, the pulse wave upstroke rises rapidly and forcefully, producing the first systolic peak ("percussion wave"). A brief decline in pressure follows because of the sudden midsystolic decrease in the rate of left ventricular ejection, when severe obstruction often develops.
This pressure trough is followed by a smaller and more slowly rising positive pulse wave ("tidal wave") produced by continued ventricular ejection and by reflected waves from the periphery.

178 - Bird facies

 

*A very small lower jaw is the commonest finding in Pierre Robin syndrome. But the growth of the mandible seems to normalize by the 5th year of life, it however gives a characteristic appearance called as "bird facies."

*The combination of a small lower jaw and the reverse tongue gives rise to acute breathing problems in a child because of airway blockage. Defects of the middle ear can lead to hearing loss. Speech defects are common in Pierre Robin syndrome because of the unusual higly placed poition of the tongue and the lower jaw.

HERE IS A LIST OF DIFFERENT TYPES OF FACIES IN DIFFERENT CONDITIONS :

1. Mask like facies = Parkinsonism.

2. Elfin facies = William's syndrome.

3. Moon facies = Cushing's syndrome.

4. Snarling facies = Myasthenia gravis.

5. Mitral facies = Mitral stenosis.

6. Ashen grey facies = Myocardial Infarction.

7. Mouse facies = Chronic Renal Failure (CRF)

8. Adenoid facies = Adenoid hypertrophy.

9. Leonine facies = Lepromatous leprosy .

10.  Bird facies = Pierre Robin syndrome.

11. Mongoloid facies = Down's syndrome.

12. Coarse facies = Most of the inborn errors of metabolism (IEM) viz. the muco- polysaccharidoses (MPS), mucolipidoses (ML), fucosidoses mannosidoses, sialidoses, aspartylglycosaminuria, generalised gangliosidosis(GMl ) and Austin's variant of metachromatic leukodystrophy due to multiple sulfatase deficiency (MLD-MSD) have similar appearing facies. 

13. Syphilitic facies = Congenital syphilis ( bull dog jaw)

 

177 - Leonine facies

A face that resembles that of a lion. It is seen in multiple conditions and has been classically described for Lepromatous leprosy as well as Paget's disease of bone. It is a dermatological symptom, with characteristic facial features that are visible on presentation and is useful for focusing on differential diagnosis.
  

Differential diagnoses include the following:

* Lepromatous leprosy
* Paget's disease of bone
* Mycosis fungoides
* Amyloidosis
* Lichen myxedematosus
* Actinic reticuloid
* Leishmaniasis (Post Kala azar dermal leishmaniasis)
* Lipoid proteinosis
* Progressive nodular histiocytosis
* Mastocytosis 

176 - Cancer Predisposition Syndromes and Associated Genes

Syndrome Gene Chromosome Tumors Ataxia telangiectasia ATM  11q22-q23 Breast cancer Autoimmune lymphoproliferative syndrome FAS FASL 10q24 1q23 Lymphomas Bloom syndrome BLM  15q26.1 Cancer of all types Cowden syndrome PTEN  10q23 Breast, thyroid Familial adenomatous polyposis APC  5q21 Intestinal adenoma, colorectal cancer Familial melanoma p16INK4  9p21 Melanoma, pancreatic cancer Familial Wilms tumor WT1  11p13 Pediatric kidney cancer Hereditary breast/ovarian cancer BRCA1 BRCA2 17q21 13q12.3 Breast, ovarian, colon, prostate Hereditary diffuse gastric cancer CDH1  16q22 Stomach cancers Hereditary multiple exostoses EXT1 EXT2 8q24 11p11-12 Exostoses, chondrosarcoma Hereditary prostate cancer HPC1  1q24-25 Prostate carcinoma Hereditary retinoblastoma RB1  13q14.2 Retinoblastoma, osteosarcoma Hereditary nonpolyposis colon cancer (HNPCC) MSH2 MLH1 MSH6 PMS2 2p16 3p21.3 2p16 7p22 Colon, endometrial, ovarian, stomach, small bowel, ureter carcinoma Hereditary papillary renal carcinoma MET  7q31 Papillary renal tumor Juvenile polyposis SMAD4  18q21 Gastrointestinal, pancreatic cancers Li-Fraumeni TP53  17p13.1 Sarcoma, breast cancer Multiple endocrine neoplasia type 1 MEN1  11q13 Parathyroid, endocrine, pancreas, and pituitary Multiple endocrine neoplasia type 2a RET  10q11.2 Medullary thyroid carcinoma, pheochromocytoma Neurofibromatosis type 1 NF1  17q11.2 Neurofibroma, neurofibrosarcoma, brain tumor Neurofibromatosis type 2 NF2  22q12.2 Vestibular schwannoma, meningioma, spine Nevoid basal cell carcinoma syndrome (Gorlin's syndrome) PTCH  9q22.3 Basal cell carcinoma, medulloblastoma, jaw cysts Tuberous sclerosis TSC1 TSC2 9q34 16p13.3 Angiofibroma, renal angiomyolipoma Von Hippel–Lindau VHL  3p25-26 Kidney, cerebellum, pheochromocytoma

Note: All the above mentioned syndromes show Autosomal Dominant inheritance except Ataxia telangiectasia and bloom syndrome which are  Autosomal recessively inherited .