Showing posts with label Pulmonology. Show all posts
Showing posts with label Pulmonology. Show all posts

Saturday, November 2, 2019

Pulmonary hypertension notes


Pulmonary hypertension (PH) is defined as a resting mean pulmonary artery pressure of 25 mm Hg or greater measured during right heart catheterization.

(How I remember the number 25 - PH: 2 letters, Hyper: 5 letters).

Classification of Pulmonary Hypertension mnemonic

"A heart lung chronic thrombotic unclarity"
1: pulmonary Arterial hypertension
2: PH due to left-sided heart disease
3: PH due to lung diseases and/or hypoxia
4: Chronic thromboembolic pulmonary hypertension and other pulmonary artery obstructions
5: PH with unclear or multifactorial causes

The transpulmonary pressure gradient (TPG): The difference between mean pulmonary arterial pressure (mPAP) and left atrial pressure (LAP, commonly estimated by pulmonary capillary wedge pressure PCWP).

A TPG of >12 mmHg would result in a diagnosis of “out of proportion” pulmonary hypertension - suggesting intrinsic pulmonary vascular disease in patients with left-heart conditions associated with increased pulmonary venous pressure.

Will update post as I learn more... 


Monday, May 27, 2019

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

Tuesday, April 23, 2019

Think before you order a test: High resolution CT scan (HRCT)


Let's talk about HRCT today!

HRCT is the use of thin-section CT images (0.625-mm to 1.5-mm slice thickness) with a high spatial frequency reconstruction algorithm, to detect and characterize diseases that affect the pulmonary parenchyma and small airways.

HRCT cuts THIN slices.

Awesome, isn't it? Why not use an HD camera for every photograph?

Because it comes with a price!

Thursday, March 21, 2019

A-a Gradient

A-a gradient =[PAO2 - PaO2]

A-a gradient = difference between alveolar PO2 and arterial PO2

PAO2 = alveolar PO2 (calculated from the alveolar gas equation)

PaO2 = arterial PO2 (measured in arterial blood)

PAO2 =150 - PaCo2/0.8

Normal range for A-a gradient is

10-15 mm Hg

ALL causes of hypoxemia lead to ↑ A-a gradient, EXCEPT:

Hypoventilation, high altitude, upper airway obstruction (e.g. epiglottitis from Haemophilus influenzae, or croup from parainfluenza virus)

Everything else will cause ↑ A-a gradient (e.g. shunt, V/Q mismatch, etc.).  

It's much better to remember the exceptions, then everything else becomes the rule!

Also to adjust for age, the thumb rule to calculate A-a gradient is :

Age /4   plus 4

A-a gradient >30 is considered elevated regardless of age.

Bhopalwala. H

Catheter Removal Timing

Removal — Following diagnosis of catheter-related infection, catheter removal is warranted in the following circumstances :

●Severe sepsis

●Hemodynamic instability

●Endocarditis or evidence of metastatic infection

●Erythema or exudate due to suppurative thrombophlebitis

●Persistent bacteremia after 72 hours of antimicrobial therapy to which the organism is susceptible

Source :Uptodate

Bhopalwala. H

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

Tuesday, March 19, 2019

Catheter Related Candidemia Treatment Indications

Empiric therapy for suspected catheter-related candidemia should be administered for septic patients with the following risk factors:
●Total parenteral nutrition
●Prolonged use of broad-spectrum antibiotics
●Hematologic malignancy
●Hematopoietic cell or solid organ transplant
●Femoral catheterization
●Colonization due to Candida species at multiple sites

Source: Uptodate

Bhopalwala. H

Antibiotic Lock Therapy

Antibiotic lock therapy —
The premise of ALT is to achieve sufficient therapeutic concentrations to kill microbes growing in a biofilm . ALT may be a useful adjunctive therapy together with systemic antibiotic therapy for intraluminal infections due to coagulase-negative staphylococci or gram-negative organisms in the setting of CRBSI (Catheter Related Blood Stream Infection) when the catheter cannot be removed .
ALT should not be used for extraluminal infections nor for management of infections due to S. aureus, P. aeruginosa, drug-resistant gram-negative bacilli, or Candida.

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

Monday, March 18, 2019

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 CO2 eliminated/O2 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

Wednesday, March 6, 2019


Pneumonia types — The 2016 Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) guidelines distinguish the following types of pneumonia :

●Hospital-acquired (or nosocomial) pneumonia (HAP) is pneumonia that occurs 48 hours or more after admission and did not appear to be incubating at the time of admission.

●Ventilator-associated pneumonia (VAP) is a type of HAP that develops more than 48 hours after endotracheal intubation.

Bhopalwala. H

Sunday, December 2, 2018

Peculiar pattern of pulmonary edema

Usually, left-sided cardiac pathology causes bilateral pulmonary edema but still, the unilateral pattern is seen in a fair number of cases, usually involving right lung parenchyma.

Likely mechanisms include:

1) Lymphatic drainage on the right side is via low caliber right bronchomediastinal trunk as opposed to the more robust thoracic duct on the left side.

2) Numerous conditions ranging from hypertension to valvular pathology can cause enlargement of the left side of the heart.
This will preferentially impinge on the left pulmonary artery causing reduced capillary perfusion and ultimately congestion of left lung parenchyma.

3) In cases of mitral regurgitation jet of regurgitating can preferentially impact either of the right or left pulmonary veins, hence explaining more profound edema on either side.

So, if according to the patient's history and clinical examination suspicion of cardiac failure remains high, then immediate intervention with diuretics and nitrates is warranted in spite of a unilateral pattern of pulmonary edema.

Kirtan Patolia

Monday, November 12, 2018

True or False #4

1. Imaging is contraindicated in pregnancy for diagnosing latent TB. T or F

2. Check for latent TB before prescribing Infliximab. T or F


1. False

Diagnostic evaluation after positive test — Patients with a positive TST or IGRA must undergo clinical evaluation to rule out active tuberculosis. This includes evaluation for symptoms (eg, fever, cough, weight loss) and radiographic examination of the chest (with appropriate shielding), regardless of gestational age.

Patients with a positive TST or IGRA with no evidence of active TB may be presumed to have latent TB.

2. True

Toxicity of Infliximab includes :

Respiratory infection (possible reactivation of latent TB)



Last man standing wins. Keep grinding.

True or False #2

1. Herpangina involves the anterior oropharynx with grey vesicles and ulcers. T or F

2. Pleurodynia is also known as Bornholm disease. T or F


1. False

Herpangina is caused by Coxsackievirus and involves the posterior oropharynx

Herpetic gingivostomatitis caused by HSV involves the anterior oropharynx and grey vesicles and ulcers

2. True

Pleurodynia — Pleurodynia is an acute enteroviral illness characterized by fever and paroxysmal spasms of the chest and abdominal muscles . Most cases occur during localized summer outbreaks among adolescents and adults. Regional and nationwide outbreaks involving a large number of older children and young adults have been reported at infrequent intervals, often separated by decades. The role of the group B coxsackieviruses, the most important cause of epidemic pleurodynia, was established in 1949 . Other agents rarely implicated in pleurodynia include echovirus serotypes 1, 6, 9, 16, and 19 and group A coxsackievirus serotypes 4, 6, 9, and 10 .

Pleurodynia can mimic more serious diseases, including bacterial pneumonia, pulmonary embolus, myocardial infarction, acute surgical abdomen, and herpes zoster infection. Most patients are ill for four to six days. Children have milder disease than adults, who are often confined to bed.

Sunday, February 4, 2018

Crepts : An Overview

Hi everyone ! Just a short summary post on Crepts. Would like to thank Upasana for suggesting this topic ! 


1 . Synonyms = Rales , Crepitations , Crackles

2 . Character = Rustling/  Bubbling type of sounds
Short , sharp, interrupted sounds.
(Wet Sounds)

3 . Types =

Fine and Coarse crepts -
Differentiation is clinical - fine crepts have a shorter amplitude while Coarse crepts have a higher amplitude and are usually louder with a lower frequency.

So ,  if you hear crepts of mellow tone (lighter quality) , with a very small gap between two crepts they are fine.
If they are very harsh and widely spaced they're likely to be Coarse crepts. 

As a thumb rule , fine crepts are generally Cardiac and Coarse are of Respiratory origin (with exceptions).

4 . Special types of Crepts :

Velcro crepts = Fine crepts of Interstitial Lung Disease

Coarse leathery crepts = Harsh Coarse crepts of Bronchiectasis

5 . Mechanism of Crepts :
- unclear but certain reasons are hypothesized.
- When an Alveolus is in a  collapsed state and then bursts open it produces a crept.
So for example -  in a pneumonia due to the exudates accumulated in the alveolus there is very little air in it and the alveolus is in a collapsed state at the end of expiration. Due to this, when a person inspires the collapsed alveolus and airway suddenly open with a snap and produce a sharp sound due to sudden pressure equalisation.
When many such alveoli open in a serial fashion from top to bottom we hear the typical bubbling sound of 'Crepts'.

- Older reasons - Air bubbling through exudative alveolus. But rejected as other forms of airway Obstruction like Bronchiectasis and Fibrosis causing collapsed airways also causes crepts.

6 . Causes of Crepts :

- Pneumonia / Consolidation
- Interstitial Lung Disease and Pulmonary Fibrosis
- Bronchiectasis
- Bronchitis
- Lung Abscess
- At times in COPD patients - Expiratory crepts may be heard.

Cardiac causes :
- Pulmonary edema due to Left Ventricular Failure.

7 . Cardiac vs Respiratory crepts :

Cardiac crepts are typically Basal and Bilateral , are fine crepts , associated with features of Heart Failure and may disappear on adminstering diuretics.
The opposite is true for Respiratory crepts.

Hope this was concise enough and helped !
Happy Studying!
Stay Awesome!

~ A.P.Burkholderia