Diagnosing the cause of polycythemia

Polycythemia refers to an increased hemoglobin concentration and/or hematocrit in peripheral blood.
For Diagnosing the specific cause of polycythemia follow these 3 steps:

STEP1: First check for RBC mass
1)Elevation of Hgb and/or Hct due to a decrease in plasma volume alone (ie, without an increase of the RBC mass) is referred to as relative polycythemia.

2)An increase of RBC mass refers to Absolute polycythemia. It can be categorized as either primary or secondary polycythemia.

STEP2: To diagnose the causes of absolute polycythemia. Check for EPO levels
1)Primary polycythemia is caused by a mutation in RBC progenitor cells that results in increased RBC mass. So there is a decrease in EPO levels. Ex: polycythemia vera (PV)
2)Secondary polycythemia refers to an increase of RBC mass caused by elevated serum EPO. Most often, this is due to an appropriate physiologic response to tissue hypoxia, or by autonomous EPO production(eg, an EPO-secreting tumor) 

STEP3: To diagnose the causes of secondary polycythemia. Check PaO2 and SaO2 levels
1)If PaO2<65% and SaO2<92% then it is because of chronic hypoxia due to high altitude, COPD, Smoking, etc.
2)If PaO2 and SaO2 levels are normal then consider EPO-secreting tumor(renal cell carcinoma, pheochromocytoma).

-Srikar Sama

Places to Target for Research

Places to target first for a Research Position (Big Guns) :

Mayo Clinic, Rochester

Mayo Clinic, Florida

Cleveland clinic, Ohio

Cleveland clinic, Florida

Email Format for Research

Email Format  for a Research Position

Hello Dr. XYZ,

I am ABC, a medical student, currently doing clinical elective rotations.

I'm highly interested in cardiology. Your /Case Western Reserve University's research work ( refer to either the person's or the University's work) , particularly in general cardiology and electrophysiology is exemplary.

I believe you accept volunteer Research Scholars. It would be an honor to work in this institute as a Research Scholar.

I would be willing to work for a year, and would also consider an unpaid position.

I am attaching my CV with this email.

Hoping to hear back from you.

Wish you a happy new year.

Thanks.

Hope this helps :)

Bhopalwala. H

How to Land a Research Spot in USA

Hey guys, how's it going?

So this post is going to be about how to land a research position in USA.

First of all I would like to briefly speak about  why it is important to have some research experience in USA. Common idea is it helps people to build a strong CV to cover up low scores or any red flags in the CV. What I have realized is that it is not the only benefit, to get into a competitive specialty for residency and also for future fellowships it's very important to have some research background in the field of your interest.

Now let's talk about the steps to go through before you land a research spot.

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

Immunization certificate sample for electives and observerships

Hello,

Since many of you emailed me regarding the  immunization form, I thought of sharing it on Google Docs.

Step 2 CS: Neurology Case mnemonic

The following mnemonic (HDFC ST) helps me cover all bases in a Neurology case.

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

Types of Sphenoid Sinues.

Hello Guy's!

Here's a sneak peek into the world of Neurosurgery!

In cases of Pituitary Adenomas, the general surgical approach is a TransNasal TransSphenoidal Approach for the excision of the lesion.

To know the type of sphenoid sinus is an important step in the pre-operative planning for the surgery. It also helps in estimating the site where we are most likely to encounter the tumor and the pituitary gland.

Hamburger classified 3 types of pneumatization based on its relationship to the sella turcica.

1)Conchal (rudimentary or absent sphenoid sinus)

2)Presellar (a posterior sphenoid sinus wall that is separated from sella by thick bone).

3)Sellar (a posterior sphenoid sinus wall that is adjacent to sella).

That's all for now... Time to Scrub.

Let's learn Together!

~Medha Vyas.

Restrictive vs Liberal approach to transfusion in Sepsis

Hello everyone, 

Here are some studies on approach to blood transfusion during sepsis:

One multicenter randomized study of 998 patients with septic shock reported no difference in 28-day mortality between patients who were transfused when the hemoglobin was ≤7 g/dL (restrictive strategy) and patients who were transfused when the hemoglobin was ≤9 g/dL (liberal strategy) . The restrictive strategy resulted in 50 percent fewer red blood cell transfusions (1545 versus 3088 transfusions) and did not have any adverse effect on the rate of ischemic events (7 versus 8 percent).

One randomized trial initially reported a mortality benefit from a protocol that included transfusing patients to a goal hematocrit >30 (hemoglobin level 10 g/dL) . However, similarly designed studies published since then reported no benefit to this strategy. 

Bhopalwala. H

Source: UpToDate