COVID-19: Pathophysiology and microbiology

COVID-19: Pathophysiology and microbiology

Facebook: PFT-1

Q1) Which of the following is/are not a contraindications of performing PFT(Pulmonary function test)? 

A) MI within one year

B) Unstable angina

C) Recent thoraco-abdominal surgery

D) Recent ophthalmic surgery

E) Past history of pneumothorax

So correct options are - A and E

Following are contraindications to perform pulmonary function test. 

Mnemonic: UR IRcTC

U- Unstable angina

R- Recent thoracoabdominal surgery

I- Myocardial infarction within the last month

R- Recent ophthalmic surgery

T- Thoracic or abdominal surgery 

C- Current pneumothorax

That's it! 

-Demotional bloke. 

Parasitic infections and Asthma

In parasitic infection, polyclonal IgE produced by body occupies the receptor produced by mast cells. This leads to decrease action of specific IgE required for asthma. 

This mechanism is probably the cause of decrease prevalence of asthma in tropical population. 

That's it 

-Demotional bloke

Choristomas Vs Hamartomas

I get super confused with both the following terms, so I made a lame technique to remember both of them. 

Choristomas:

It sounds more like a Christmas. So Christmas tree is usually not grown in India but we do keep it as a sign of Christmas. 

So Christmas tree is normal, but the site (India or any other habitat) is not the usual site of tree, so let's say abnormal. 

So Choristomas is normal tissue at abnormal anatomical sites.

Example - Normal pancreatic cells under the small bowel mucosa.

They are not considered as neoplasm.

Hamartomas:w

'Hamara' in Hindi means 'mine'. 

Remember: this place is mine. So here, place is normal and tissue is abnormal!

That is, abnormal tissue at normal anatomical sites.

Example - Lung hamartomas exhibit cartilage, bronchi, and blood vessels. 

They are considered as neoplasm.

That's it! 

-Demotional bloke

Egg shell calcification

Following are the cases in which we get eggshell calcification of lympho nodes on radiography. 

Mnemonic:

SSRI Love Hitting BAT

(Lame? I know!) 

S-Silicosis

S-Sarcoidosis

R- After Radiotherapy

I L- Post irradiation lymphoma

H- Histoplasmosis

A- Amyloidosis

T- Tuberculosis

That's it ! 

- Demotional bloke

Causes of Acute Pancreatitis mnemonic

Hi!

Causes of Acute Pancreatitis mnemonic :

ABCDEFGHIjK

Differential Diagnosis of Acute Pancreatitis mnemonic

Hi!

Differential Diagnosis of Acute pancreatitis mnemonic:

HI-PANC

Extra - articular manifestations of RA ( Notes and mnemonic )

Hi!

Extra- articular manifestations of Rheumatoid arthritis :

( mnemonic - NOVELA is FrickiN' Hot! )

Multiple Myeloma notes and mnemonics

Hi!

Multiple myeloma - everything P

- malignant Proliferation of Plasma cells derived from a single clone.

- Immunoglobulin produced is a "ParaProtein" (M- protein)

- POEMS syndrome

BONE MARROW INVOLVEMENT

- Pancytopenia

PERIPHERAL BLOOD

- plasma cell leukemia ( greater than 2,000 per mm3 )

BONE INVOLVEMENT

- punched-out lesions in radiographs of flat bones

- bone pain

- pathological fractures

RENAL INVOLVEMENT

- Bence -Jones proteinuria

- production of excess Amyloid protein

- hyPer- calci -emia and -uria

These three result in renal damage and renal failure.

IMMUNE SYSTEM INVOLVEMENT

- prone to infections, particularly in respiratory and urinary tract.

HYPERVISCOSITY SYNDROME

( mnemonic - HPRVSCST )

- Headache

- Postural hypotension

- Retinal venous congestion

- Vertigo

- Strain (blurred vision)

- Congestive cardiac failure

- subtype IgA

- nysTagmus

CLOTTING PROBLEMS

- purpura

- profuse bleeding ( epistaxis, gastrointestinal )

NEUROLOGICAL MANIFESTATIONS

- peripheral neuropathy

- compressive myopathy

- carpal tunnel syndrome ( nerve entrapment)

- Amyloidosis.

SERUM STUDIES

- total serum protein raised

- low albumin

- high globulin ( decreased A:G ratio )

- high beta-2 microglobulin ( greater than 5.5 mg/dL means poor prognosis; stage III)

Plasmacytomas in Paraskeletal soft tissues - poor prognosis; treated by palliative radiotherapy.


That's all
Anything more to add, you're most welcome :)
- Jaskunwar Singh

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. :)

Of Surgery and Wounds

Hey guys, here’s a classification of surgical procedures, wounds and their infection risk.

[Please click on the image to enhance it]

Thank you for your time.
- Ashish Singh.

What Is Going On In Fibromyalgia?

Hi there! Let’s talk about pathophysiology of fibromyalgia; a chronic disorder where fatigue and widespread pain feature prominently.

Current hypothesis says, it’s caused by aberrant peripheral and central pain processing.
Two key features are allodynia, that is, pain in response to a non-painful stimulus and hyperaesthesia, which is, exaggerated perception of pain in response to mildly painful stimulus.

Modern research says, certain antidepressants- with both serotonergic and noradrenergic activity- such as TCAs and venlafaxine, can relieve pain and other symptoms; suggesting the pathway involvement.

Some evidence says, alternative therapies such as acupuncture and spa therapies alleviate pain, which have been postulated to act via similar spinal pain-modulatory pathways.

CSF studies show increased levels of substance P, with decreased levels of noradrenaline and serotonin metabolites. All three are neurotransmitters involved in descending pain-modulatory pathways in the spinal cord.

PET images show an abnormal central dopamine response to pain.

The critical question here is: what is cause and what is effect?

Small sample size and short periods of study, remain the most cumbersome challenge to our complete understanding of fibromyalgia.  



Thank you for reading.
- Ashish Singh.

Sites of Bronchiectasis

Bronchiectasis site in lung depends upon the etiological factors

Upper lobe bronchiectasis:

Mnemonic: Upper - PCT
Upper- Upper lobe
P- Post radiation
C- Cystic fibrosis
T- Tuberculosis

Middle lobe bronchiectasis:

Mnemonic: MMC (Like BMC!)
M- Middle lobe
M- Mycobacterium avium
C- Ciliary dyskinesia

Lower lobe bronchiectasis:

Mnemonic: Left-ICA (Internal carotid artery)
Left- Lower lobe
I- Interstitial lung disease
CA- Chronic aspiration

That's all.
Thank you :)

-Demotional bloke

What Is Going On In Migraine?

Despite the high prevalence of migraines, the underlying pathophysiology is poorly understood.

What was thought?
Cerebral and meningeal arteries dilatation. Now largely disproven.

What do we think?
- MRI says episodic cerebral edema with dilatation of intracereberal vessels and less water diffusion that doesn’t respect vascular territories.

- PET says it’s a subcortical disorder affecting modulation of sensory processing.

- Magneto-EncepaloGraphic (MEG) scan suggests failure of inhibitory circuitry in the visual cortex.

- Hormones play a role. Migraines occur just as commonly in males as in pre-pubertal and post-menopausal females but the ratio tilts towards women of reproductive age group by 3:1. About half of the women complain of migraine synchrony with menses.

- 5-HT overload as suggested by its metabolites in the urine. While the exact significance is controversial, the efficacy of Triptans (5-HT 1b/1d agonists) supports its role.

- Trigeminal nerve dysfunction suggested by blockade of trigeminal nerve impulses by Triptans. They also inhibit release of substance P and pro-inflammatory neuropeptides.

This is what we know so far. To thread this string is your responsibility, future Dr. Neurologist. Good luck!



- Ashish Singh

Pathophysiology: Diabetic Ketoacidosis

Hello guys, here’s a whiteboard summary of how DKA happens.

[Please click on the image to enhance it]

- DKA is a medical emergency. It’s a complication of type 1 diabetes.
- DKA has a triad of hyperglycemia, ketosis [metabolic acidosis] and dehydration.
- Main ketone bodies are beta-hydroxybutyrate and acetoacetate. Acetone is only a minor ketoacid.
- Lactic acidosis also contributes to metabolic acidosis.
- More glucose in blood leads to more glucose filtered into urine causing osmotic diuresis.


- Ashish Singh 

Pathophysiology: Multiple Sclerosis

Hey guys, let’s look at the fundamentals of multiple sclerosis.

Multiple sclerosis is an autoimmune disease of the CNS characterised by

- chronic inflammation

- demyelination

- reactive gliosis/ scarring

- neuronal loss

with a course that is relapsing-remitting or progressive

and lesions that are disseminated in time and space.

Here’s how it happens:

[Please click on the image to enhance it]

- Ashish Singh

Lung Biopsy in VAP

Lung biopsy in Ventilator-associated Pneumonia may be reserved for patients in whom infiltrates are progressive despite antibiotic therapy or patients in whom a non-infectious etiology is suspected.

The purpose of acquiring tissue under these circumstances is to identify a pathogen that may have been missed with previous sampling or a pathogen that is difficult to culture (eg, fungus, herpes viruses) or to identify a noninfectious process masquerading as infection (eg, cancer, cryptogenic organizing pneumonitis, lymphangitis, interstitial pneumonitis, vasculitis).

Source: Uptodate

Bhopalwala. H

Timing of Catheter Replacement in CRBSI

In general, the patient should receive antibiotic therapy for at least two to three days following device removal prior to device replacement. At the time of device replacement, the patient should be hemodynamically stable with negative blood cultures and no sequelae of bloodstream infection .In addition, for patients with CRBSI ( Catheter Related Blood Stream Infection) due to S. aureus, a new catheter may be placed if additional blood cultures demonstrate no growth at 72 hours

Source: Uptodate

Bhopalwala. H

Right to left shunt causing Hypoxemia

A right-to-left shunt exists when blood passes from the right to the left side of the heart without being oxygenated. There are two types of right-to-left shunts:

●Anatomic shunts exist when the alveoli are bypassed. Examples include intracardiac shunts, pulmonary arteriovenous malformations (AVMs), and hepatopulmonary syndrome.

●Physiologic shunts exist when non-ventilated alveoli are perfused. Examples include atelectasis and diseases with alveolar filling (eg, pneumonia, acute respiratory distress syndrome).

Right-to-left shunts cause extreme V/Q mismatch, with a V/Q ratio of zero in some lung regions. The net effect is hypoxemia, which is difficult to correct with supplemental oxygen.

The degree of shunt can be quantified from the shunt equation:

Qs/Qt  =  (CcO2  -  CaO2)  ÷  (CcO2  -  CvO2)

where Qs/Qt is the shunt fraction, CcO2 is the end-capillary oxygen content, CaO2 is the arterial oxygen content, and CvO2 is the mixed venous oxygen content. CaO2 and CvO2 are calculated from arterial and mixed venous blood gas measurements, respectively. CcO2 is estimated from the PAO2.

Source: UpToDate

Bhopalwala. H

Causes of Hypoventilation

Hypoventilation — 

The lung alveolus is a space in which gas makes up 100 percent of the contents. This means that once the partial pressure of one gas rises, the other must decrease. Both arterial (PaCO₂) and alveolar (PACO₂) carbon dioxide tension increase during hypoventilation, which causes the alveolar oxygen tension (PAO₂) to decrease. As a result, diffusion of oxygen from the alveolus to the pulmonary capillary declines with a net effect of hypoxemia and hypercapnia. Because the respiratory quotient (Defined as CO_{2 eliminated}/O_{2 consumed}) is assumed to be 0.8, hypoventilation affects PaCO₂more than O₂.

Hypoxemia due to pure hypoventilation (ie, in the absence of an elevated A-a gradient) can be identified by two characteristics. First, it readily corrects with a small increase in the fraction of inspired oxygen (FiO₂). Second, the paCO₂ is elevated. An exception exists when the hypoventilation is prolonged because atelectasis can occur, which will increase the A-a gradient . Abnormalities that cause pure hypoventilation include:

●CNS depression, such as drug overdose, structural CNS lesions, or ischemic CNS lesions that impact the respiratory center

●Obesity hypoventilation (Pickwickian) syndrome

●Impaired neural conduction, such as amyotrophic lateral sclerosis, Guillain-Barré syndrome, high cervical spine injury, phrenic nerve paralysis, or aminoglycoside blockade

●Muscular weakness, such as myasthenia gravis, idiopathic diaphragmatic paralysis, polymyositis, muscular dystrophy, or severe hypothyroidism

●Poor chest wall elasticity, such as a flail chest or kyphoscoliosis

Bhopalwala. H