Wednesday, March 20, 2019
How to Land a Research Spot in USA
Tuesday, March 19, 2019
Catheter Related Candidemia Treatment Indications
Antibiotic Lock Therapy
Timing of Catheter Replacement in CRBSI
Immunization certificate sample for electives and observerships
Since many of you emailed me regarding the immunization form, I thought of sharing it on Google Docs.
Monday, March 18, 2019
Step 2 CS: Neurology Case mnemonic
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 13, 2019
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.
Monday, March 11, 2019
Restrictive vs Liberal approach to transfusion in Sepsis
Norepinephrine in ICU
Norepinephrine (noradrenaline) Levophed
8 to 12 mcg/minute (0.1 to 0.15 mcg/kg/minute)
A lower initial dose of 5 mcg/minute may be used, eg, in older adults 2 to 4 mcg/minute (0.025 to 0.05 mcg/kg/minute) 35 to 100 mcg/minute (0.5 to 0.75 mcg/kg/minute; up to 3.3 mcg/kg/minute has been needed rarely)
Initial vasopressor of choice in septic, cardiogenic, and hypovolemic shock.
Wide range of doses utilized clinically.
Must be diluted; eg, a usual concentration is 4 mg in 250 mL of D5W or NS (16 micrograms/mL).
Bhopalwala. H
Milrinone in ICU
Inotrope (nonadrenergic, PDE3 inhibitor)
Milrinone Primacor
Optional loading dose: 50 mcg/kg over 10 minutes (usually not given) 0.125 to 0.75 mcg/kg/minute
Alternative for short-term cardiac output augmentation to maintain organ perfusion in cardiogenic shock refractory to other agents.
Increases cardiac contractility and modestly increases heart rate at high doses; may cause peripheral vasodilation, hypotension, and/or ventricular arrhythmia.
Renally cleared; dose adjustment in renal impairment needed.
Must be diluted; eg, a usual concentration is 40 mg in 200 mL D5W (200 micrograms/mL); use of a commercially available pre-diluted solution is preferred.
Bhopalwala. H
Dobutamine in ICU
Dobutamine Dobutrex
0.5 to 1 mcg/kg/minute
(alternatively, 2.5 mcg/kg/minute in more severe cardiac decompensation) 2 to 20 mcg/kg/minute
20 to 40 mcg/kg/minute;
Doses >20 mcg/kg/minute are not recommended in heart failure and should be reserved for salvage therapy
Initial agent of choice in cardiogenic shock with low cardiac output and maintained blood pressure.
Add-on to norepinephrine for cardiac output augmentation in septic shock with myocardial dysfunction (eg, in elevated left ventricular filling pressures and adequate MAP) or ongoing hypoperfusion despite adequate intravascular volume and use of vasopressor agents.
Increases cardiac contractility and rate; may cause hypotension and tachyarrhythmias.
Must be diluted; a usual concentration is 250 mg in 500 mL D5W or NS (0.5 mg/mL); use of a commercially available pre-diluted solution is preferred.
Bhopalwala. H