Posted in Uncategorized, tagged central cyanosis, central vs peripheral cyanosis, cyanosis, effect of oxygen on central cyanosis, effect of oxygen on peripheral cyanosis, peripheral cyanosis, peripheral verses central cyanosis on October 22, 2010| 1 Comment »
Answer : Peripheral cyanosis reduces or disappears , while central cyanosis persist.
This is how , 99% of cardiology fellows answered in one of my classes ! And they were quoting few references for it .
Is that correct ? If so , what is the mechanism of oxygen response ?
Comments welcome . Discussion will start soon .
Posted in Uncategorized, tagged central cyanosis, how will you diagnose cyanosis with reduced pulmonary blood flow, hypoxic spells, squatting on October 21, 2010| Leave a Comment »
During clinical examination of cyanotic congenital heart disease(CHD) , the major task is to differentiate conditions with reduced or increased pulmonary blood flow .
When a child with CHD is presented in clinical examinations , students are often asked to arrive at the diagnosis from history , physical examination before going in for ECG, X ray or echocardiography.
History, surprisingly can suggest the correct diagnosis in many (Most ?)
Reduced pulmonary blood flow is often associated with
Relief of dyspnea by assuming squatting position convey important hemodynamic information. It implies there is significant reduction in pulmonary blood flow in standing posture , that gets corrected in the squat position.For squatting to improve pulmonary blood flow there must be a communication between right and left heart .This is most often due to a large VSD, rarely an ASD .
Related article : How squatting relieves hypoxia in TOF ?
*Note : Cyanosis is not specific for reduced pulmonary blood flow. In fact , simple reduction in pulmonary blood flow per se , cannot result in significant cyanosis .There need to be admixture /or right to left to shunt to produce cyanosis .Cyanosis in pure admixutre states like TGV, Single ventricle , Common AV canal , Common atrium TAPVC, are less Dependant on the reduction of pulmonary flow. In these situations RVOT obstruction if present will aggravate the baseline cyanosis.
Examination
Apart from direct evidence for reduced pulmonary blood flow , lack of evidence for increased pulmonary flow could often mean , we are actually dealing with reduced pulmonary blood flow.
The following are the clinical clues to suspect reduced pulmonary blood flow.
* A silent heart is the hall mark of Tetrology of Fallot which constitutes 80% of all CHD with reduced pulmonary blood flow.
Posted in Cardiology - Clinical, Uncategorized, tagged central cyanosis, cyanosis in primary pulmonary hypertension, peripheral cyanosis on July 14, 2010| 2 Comments »
How central cyanosis occurs in primary pulmonary hypertension ?
While , peripheal cyanosis* is easily explained in PPH ,the mechanism of central cyanosis is not straight forward.
The following explanations are offered
* Peripheral cyanosis can occur in PPH with cardiac failure
**PFOs are often anatomically patent in 20 % of normal population , which gets functionally patent when exposed to high RA pressure
Cyanosis -A brief description .
Cyanosis occurs when the arterial saturation goes below 85 % . Cyanosis manifests in two ways . Central and peripheral.The term peripheral does not denote peripheral parts of the body rather it is peripheral circulation.(Capillary) The mechanism of peripheral cyanosis is somewhat different from central cyanosis . It is generally due to sluggish circulation , more oxygen extraction and resultant bluish discoloration .
Peripheral cyanosis is seen in finger tips, lips etc . Peripheral cyanosis can not occur in warm areas of the body for the simple reason warmth causes vasodilatation , better tissue perfusion which prevents stagnation of deoxygenated blood.
Central oxygenation defect alone can not result in classical central cyanosis .
For central cyanosis to occur , there need to be mixing of deoxygented and oxygenated blood somewhere in the circulation.(Right to left shunt in the heart or lungs )
Since it is a defect in central oxygenation it manifests in both warm mucous membranes as well as cold extremities.
