Inferior wall MI and Bezold-Jarisch reflex

Hello everyone!

Acute myocardial infarction (AMI), especially of the inferior left ventricular wall, is often associated with transient hypotension and sinus bradycardia.

Ever wondered... Why?

Kleihauer–Betke test

Kleihauer–Betke test: KB test.

1) Why do we do this test?

- To calculate Fetal RBCs in blood. This helps us to measure amount of Anti-D required to neutralize it.

2) How do we do it?

- Basically, we are going to take blood sample and add acid to it and measure red blood cells under microscope.

3) How do you differentiate Fetal and Maternal blood?

- Fetal RBCs are acid resistant. Adding acid in the preparation leads to lysis of the Maternal RBCs.

4) What are important points regarding this test that should be kept in mind while solving MCQs?

- Do not confuse it with APT test. APT is done in Alkali and it is a Qualitative test. It helps in differentiating Maternal and Fetal blood only. On the other hand, in KB test (Also know as Acid dilution test), we use Acid and we quantify Fetal blood.

- Minimum dose even after KB test is 300 microgram.

5) How do we calculate amount of Anti-D required to neutralize Fetal RBCs?

- If 20 RBCs in HPF are seen, then it means 1 ml Fetal blood is in circulation.

-‎1 ml fetal blood requires 10 microgram of Anti-D for neutralization

6) What if they don't mention "Fetal RBCs" and instead, mention "Fetal blood" in the question?

- Here is a trick. Always remember, 1 ml Fetal blood has 0.5 ml Fetal RBCs.

Applied calculations:

Q1) A Multigravida with twin pregnancy has 20 ml Fetal RBCs. How much Anti-D will be required to neutralize it?

(Take a deep breath. You don't need to worry about twin pregnancy. All the important points are already covered in above segment)

- 20 ml Fetal RBCs = 40 ml Fetal blood.
- ‎1 ml Fetal blood = 10 micrograms Anti-D

Answer = 400 micrograms Anti-D

400 micrograms is the enough amount of blood given to neutralize 40 ml fetal blood or 20 ml Fetal RBCs.
‎
(Done easily? Perfect ! Let's level up.
I want you to go through blog once again before heading down.)

Q2) This time patient comes with same clinical presentation but with 20 ml fetal blood.

- 1 ml fetal blood = 10 micrograms of the Anti-D
- ‎20 ml Fetal blood will require 200 micrograms Anti-D.

Perfect. We calculated correctly but my question is - Will you administer 200 micrograms Anti-D to the patient showing 20 ml Fetal blood to neutralize it?

Answer is big 'NO'.

Go back to bullet (4) point 2:

Minimum amount is still 300 micrograms after KB test. So you cannot administer 200 micrograms. You have to give 300 micrograms.

I hope this blog is better than my previous blogs. Any important points you have regarding KB test, do comment in comment box

That's it

-Demotional bloke

Interesting retinal peculiarities

1. The respiratory rate of the retina is twice that of the brain.

2. The retina does not require insulin for glucose to enter the cells!

3. In the retina, glycolysis occurs despite having sufficient oxygen supply.

4. The retina is not just a sensory organ. Much of the image processing occurs at the retinal level itself.

-Sushrut

D-lactic acidosis in short bowel syndrome

Hello everyone!

D-lactic acidosis is an unusual form of lactic acidosis.

Which patients develop D-lactic acidosis?
1. In patients with jejunoileal bypass, small bowel resection, or other causes of the short bowel syndrome.
2. Patient who receives or ingests a large amount of propylene glycol
3. Patients with diabetic ketoacidosis

In this post, I'm going to specifically talk about D-lactic acidosis in patients with small bowel syndrome.

How do patients with D-Lactic acidosis present?

Increased anion gap metabolic acidosis.
Neurologic findings of intermittent confusion, slurred speech, and ataxia.

Why does it happen in patients with small bowel syndrome?

Glucose and other carbohydrates are normally absorbed by the small bowel. If the small bowel is bypassed, removed, or diseased, then delivery of these substances to the colon increases.

Also, overgrowth of gram-positive anaerobes, such as Lactobacilli seen in small bowel syndrome contributes to lactic acidosis.

How is it metabolized?

D-lactate is not metabolized by L-lactate dehydrogenase, the enzyme that catalyzes the conversion of the physiologically occurring L-lactate into pyruvate. Thus, D-lactate is slowly metabolized in humans, accumulates in body fluids, and generates metabolic acidosis.

Diagnosis:
Laboratory studies show increased anion gap metabolic acidosis with normal plasma lactate levels, because the D-isomer is not measured by conventional laboratory assays for lactate. Diagnosis is confirmed by specifically measuring D-lactate.

Treatment:
Sodium bicarbonate if D-lactic acidosis and acidemia are severe.

Oral antimicrobial agents (such as metronidazole, neomycin, or vancomycin) can be used when D-lactic acidosis that decrease the number of D-lactate-producing organisms.
FYI: Although antimicrobials are sometimes helpful, they can occasionally precipitate D-lactic acidosis in susceptible subjects by causing an overgrowth of lactobacilli.

Low-carbohydrate diet (or the use of starch polymers rather than simple sugars) is also helpful because it diminishes carbohydrate delivery to the colon.

That's all!

-IkaN

INTERNSHIP DIARIES EPISODE 05 – Who Resides In Your Blood? (Blood Cultures)

It was a bright day. You reached the ICU ward and introduced yourself to the resident there.You got ready with cap and mask and asked to take vitals of patient.

"He developed a spiking fever, and the central venous catheter was removed on day 14 of treatment. Fever is not responding to antibiotics, Sir." said one resident to the  consultant.

"Send the blood for culture and inform me." said the consultant.

"Dr. Kesh , Can you arrange the items for sampling and fill up the laboratory forms?" the senior resident looks at you.

"Yes, Sir." Says you excited to know and expand your knowledge about blood culture.

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5.1 BLOOD CULTURES:

INDICATION FOR BLOOD CULTURE:

1.Where the possibility of septicemia or bacteremia is suggested by the presence of fever,shock or other signs and symptoms occurring in association with a known or suspected local infection such as sepsis in a surgical wound ,Osteomyelitis,peritonitis,Arthritis,Enteric fever.

2.Pyrexia of unknown origin (temperatures of >38.3°C (>101°F) on several occasions with fever of >3 weeks and failure to reach a diagnosis despite 1 week of inpatient investigation)

3.Unexplained leucocytosis or leucopenia

4.Suspected fungemia specially in Immunocompromised patients, HIV patients.

STEPS:

I)Obtain consent

II)Hand washing

III)Arranging items for sampling (MATERIALS REQUIRED)

·        70% isopropyl alcohol swabs

·         10% Povidone iodine swabs

·        dry cotton

·        Sterile gloves of suitable size

·        2 syringes (adult: 20 cc, paediatric: 5 cc)

·        2 needles (adult: 22 gauge or preferably larger butterfly or standard needle; paediatric: 25- or 23-gauge butterfly or standard needle)

·        Blood culture bottle (Aerobic and anerobic)

IV) vein selection

• Arterial vs venous blood

 • Indwelling arterial or venous lines

• Central or peripheral

V)Hand washing and Gloving

VI)Preparation of a skin

VII)Venepuncture and drawing a blood sample

VIII)Inoculating in blood culture bottle and shake the bottle

IX)Labelling, storing and documenting

• Ask the patient about allergies to iodine.

• Apply the tourniquet, select the site.

(Be careful that the ends of the tourniquet do not fall onto the puncture site, thereby contaminating it, if the tourniquet does accidentally touch the prepared puncture site, the site must be recleaned)

• Apply alcohol/acetone pad at the puncture site for 30 seconds till it dry.

• Apply the iodine swab, apply to puncture site, move the iodine in concentric circles outward. Keep it for 60 seconds (till it dry).

• Again, clean the site with alcohol/acetone and allow it to dry.

• Perform the venepuncture, following routine venepuncture procedures. Do not repalpate the site.

• If the blood culture is one of a series of samples to be drawn from a patient, the blood culture must be collected first.

• Withdraw needle from vein and insert into the top of the blood culture container.

(Other than syringe and needle, by closed system, consisting of vacuum bottle and double needle collection tube can be done.)

• Do not change the needle.

• Do not hold the container in your hand, this may result in a needle exposure.

• Do not push the blood. Mix the content. (An adequate space above broth ensures that blood is not injected under undue pressure and some air is still available for strict aerobes)

• Keep at room temperature.

• Label the blood specimen collected, following standard labelling procedures. Be sure to include the site used and the number of the specimen in the series ordered.

Blood Cultures should NOT be taken from the following sites

•       Veins which are immediately proximal to an existing peripheral IV cannula.

•       A femoral vein due to difficulty in skin disinfection of the site. This area poses a high risk of contamination.

•       Catheter drawn blood cultures are equally likely to be truly positive (associated with sepsis), but more likely to be colonized.

(One drawn through catheter and other drawn through vein PPV of 96%)

VOLUME OF BLOOD drawn is the single most important factor influencing sensitivity

• For adult: minimum 10 ml

 • For infant and children: 1-5 ml

1-2 ml= neonate

 2-3ml= 1 month - 2year age

 3-5ml= Older children

 • 20 ml of blood obtain in sequence is more effective and sensitive (98%) specially in intermittent bacteremia.

 • Patients who have received antibiotics should give 3 separate collections of blood. Also, one or two of which on 2nd day also.

TIMING OF BLOOD CULTURE

• Before starting antimicrobial therapy

• At the time of fever peak

 • Minimum 30-60 minute interval between 2 samples except in critically ill septic patient.

 • In continous bacteremia-timing of blood culture is not important, but in intermittent bacteremia 2 or 3 culture should be spaced an hour apart.

TEST PERFORMED AFTER SAMPLE REACH TO LABORATORY

Blood to broth ratio: 1:5 only, should not be <1:5 or > 1:10

• Agitation during incubation

-  Length of incubation: • Not more than 7 days • 5 days is sufficient • >5 day-contaminants • 7 days is useful for: • Fungemia • Bacteremia due to fastidious organisms like HACEK group, brucella, legionella • For patients suspected of endocarditis who has been treated with antimicrobial before obtaining blood culture • Mycobacterial culture > 4 weeks

• Atmosphere of incubation: aerobic and anaerobic

ASK YOUR MICROBIOLOGICAL DEPARTMENT TO HELP YOU IN SELECTION OF BROTH :

• Glucose broth: useful in endocarditis

• Bile broth: In enteric fever

• Trypticase soy broth (inhibits Neisseria and S.pneumoniae)

• Brain heart infusion broth: multipurpose broth

• Thioglycolate broth: for anaerobes

• Columbia or brucella broth

• Mycobacteria: Middlebrook 7H9 with 0.05% SPS, BHI with 0.5 % polysorbate 80

• Fungus broth

Additives in broth: • Anticoagulant- bacteria are trapped in blood clot • Antimicrobial- if patient is already in antibiotics • Anticomplementry agents- to inactivates complement action • Antiphagocytic

 Type of blood culture bottle (AEROBIC AND ANAEROBIC CULTURE BOTTLE)

• Standard aerobic bottles- most common bacterial pathogens, including aerobes, facultative anaerobes and for candidemia

• Smaller bottles are used for neonates and young children

• After inoculation, bottles are incubated aerobically.

SIGNS OF BACTERIAL GROWTH:

• Macroscopically:

-Generalized turbidity

-Hemolysis

- Gas production

- Discreate colonies on the surface of the sedimented red cells

-recoverable bacterial growth may occur before turbidity is evident.

Subculture from bottles as a routine

  • For subculture:

- Subcuture should be done at least once during the first day after 5-6 hours and at interval thereafter which should be at least twice during first 2-3 days.

• Gram stain:  Should be made and examined at the subculture stage. Any positive finding should be reported at once to clinician as the morphological type of organism may guide the physician to start antibiotic.

• Quantitative counts of bacteria in blood: Inoculate 1 ml amounts of blood into several tubes of melted agar and make pore plates either directly from patients. Another method is treat the patient sample with lytic agent. Then lysed sample is centrifuged and harvested organism cultured directly on a suitable solid medium to allow identification and to give a semi-quantitative indication of its presence in blood. (When monitoring colonization associated with a prosthesis or catheter) 

INTERPRETATION OF POSITIVE BLOOD CULTURE REPORT:

1. Whether true or contaminant (ASEPSIS, ASSES RISK FACTOR PRESENT IN PATIENT)

2.FIND THE SOURCE

3.DETERMINE THE NEED FOR TREATMENT (whether patient is toxic and in shock)

4.ADDRESS UNDERLYING INFECTIOUS FOCUS

5.LOOK FOR PATHOGEN SPECIFIC FACTORS DURING ANTIBIOTIC TREATMENT (Toxins that are produced)
6.HELPS IN IDENTIFYING OTHER RISK FACTOR WITH INFECTION (The identification of S.bovis organism also prompted the ultimate identification of colonic carcinoma, which is an underlying risk factor for S. bovis bacteremia)
7.LOOK FOR REASON OF IMMUNOCOMPROMISED STATE (Rule out malignancy or HIV as bactremia may be a result of oppurtunistic infection)

Therefore,clinical examination is of utmost important. As positive blood culture is not a disease in itself. It may be a result of underlying disease or part of complication.

After starting treatment, document the blood culture clearance duration.

SOME DEFINITIONS:

Bacteremia – presence of bacteria in blood stream.Some conditions have a period of bacteremia as part of the disease process (ex. Meningitis, endocarditis)

Septicemia – bacteremia plus clinical signs and symptoms of bacterial invasion and toxin production

Transient bacteremia lasts for minutes or a few hours and most frequently occurs after manipulation of nonsterile body sites—for example, during dental procedures; after gastrointestinal biopsy; after percutaneous catheterization of the vascular system, bladder, or common bile duct; and after surgical debridement or drainage—that is, after procedures involving contaminated or colonized skin and/or mucosal surfaces are performed and also at the onset of acute bacterial infections.

Intermittent bacteremia is defined as bacteremia due to the same microorganism that is detected intermittently in the same patient because of a cycle of clearance and recurrence. Intermittent bacteremia is often associated with undrained closed-space infections, such as intra-abdominal or soft-tissue abscesses, and may also occur in patients with liver abscesses, cholangitis, and focal infections, including pneumonia, osteomyelitis, and spondylodiscitis. 

Persistent bacteremia is a characteristic of infective endocarditis (IE) and other intravascular infections, such as vascular-graft infection, a mycotic aneurysm, or an infected thrombus. Persistent bacteremia also occurs during the early stages of systemic bacterial infections, such as brucellosis and typhoid fever.

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After labelling the sample, storing and documentation, you went to ICU again. Taking vitals and documenting it in files. Feeling happy to learn about blood culture. 

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HAPPY STUDYING !

UPASANA Y. AND JAY

Fas- fas ligand interactions and uveitis

-Fas ligand/ FasL/ CD95 ligand is a type 2 membrane protein belonging to the TNF superfamily and is found on lymphocytes.

-In the eye, it is expressed on Iris and corneal endothelial cells.

-In the rest of the body, it is expressed on the thymus, testes, and the brain.

-Liver and intestines express this only in periods of severe inflammatory process.

- Apoptosis of the T lymphocytes can be triggered by FasL. Loss of this mechanism is touted to be one of the causes of uveitis.

Mechanism by which it acts is believed to be the selective apoptosis of cells producing TNF or by IL2 activation of lymphocytes.

-Sushrut

Effector blockade in the eye.

This is a mechanism by which the eye wards off the secondary effector phase of the immune response arc.
Thus, the cell mediated immunity appears to function less effectively in the uvea compared to the rest of the body.
Possible mechanisms include-

1. Immunomodulatory cytokines produced by the ocular tissues.

2. Immunomodulatory neuropeptides produced by ocular nerves

3. Functionally unique APCs.

4. Compliment inhibitors

..and some other factors.

-Sushrut

Choroid and fungi

The large spaces of choroid act as a sort of trap to organisms, especially fungi. Therefore most fungal lessons of the posterior segment begin as choroiditis.

AASLD guidelines for treatment of chronic hepatitis B in pregnancy

Hello!

Here is a quick summary.

Relative risk of invasive breast carcinoma based on histological examination

Hello Awesomites!

I was going through some questions on Breast cancer. Found this piece of information.

Based on histological examination of benign breast tissue, we can assess the relative risk of invasive breast carcinoma.

Why do we want to assess this? In some studies it has been found that histologic features, the age at biopsy, and the degree of family history are major determinants of the risk of breast cancer after the diagnosis of benign breast disease. 

1. Findings suggestive of No increased risk
-Adenosis (sclerosing or fibroid)
-Cystic (macro & /micro)
-Duct ectasia
-Fibrosis
-Fibroadenoma
-hyperplasia
-Mastitis
-Squamous metaplasia
-Periductal Mastitis

2. Findings suggestive of slightly increased risk (1.5 to 2 times)
-Hyperplasia, moderate or florid, solid or papillary
-papilloma with fibrovascular core

3. Finding suggestive of moderately increased risk (5 times)
-Atypical hyperplasia, ductal or lobular

4. Insufficient data to assign a risk
-solitary papilloma of lactiferous sinus
-Radical scar Lesion

Happy Studying!
Upasana Y. :)

Chronic thromboembolic pulmonary hypertension (CTEPH)

Hello everyone,

We will be talking about CTEPH today.

Calot's triangle vs Cholecystohepatic triangle

Hello Awesomites!

I would like to highlight difference between these two terms. It is confusing.

1.Cholecystohepatic triangle:

Medial boundary- Common hepatic duct
Inferior boundary- Cystic duct
Superior boundary- Inferior edge of liver

2. Calot's triangle:

Medial boundary- Common hepatic duct
Inferior boundary- Cystic duct
Superior boundary- Cystic artery

Happy Studying!
Upasana Y. :)

Efferent optic nerve fibres

It's interesting to note that the optic nerve, which is considered to be a purely sensory nerve has some efferent fibres, that is, fibres from the brain to the optic disc. The presumed role of these fibres is in dreams, where the brain sends impulses to the retina, image is generated and it is carried back to the brain via the afferent fibres.

-Sushrut