VALSALVA
www.propofology.com
Dr. David Lyness
@Gas_Craic
Forced expiration against a closed glottis after a full inspiration.
Standardised form 40 mmHg held for 10 seconds
Previously used to expel pus from the middle ear.
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Phase I
Blood is expelled from the thoracic vessels by the increase in intrathoracic pressure.
Blood is expelled from the thoracic vessels by the increase in intrathoracic pressure.
MAP transiently goes up due to the increased pressure on the aorta.
Phase II
The increase in intrathoracic pressure causes a reduction of venous return, lowering the preload and BP
Phase II
The increase in intrathoracic pressure causes a reduction of venous return, lowering the preload and BP
The transient raise of MAP seen in phase one, falls down because of reduction in cardiac output
The baroreceptor reflex is activated, causing vasoconstriction and a tachycardia, raising BP towards normal
The baroreceptor reflex is activated, causing vasoconstriction and a tachycardia, raising BP towards normal
(The HR is increasing to compensate for the reduction in cardiac output)
Phase III
As intrathoracic pressure suddenly drops there is pooling of blood in the pulmonary vessels, causing a further drop in BP.
Phase III
As intrathoracic pressure suddenly drops there is pooling of blood in the pulmonary vessels, causing a further drop in BP.
The pressure keeping the blood out has suddenly been released = dip in BP again and a compensatory increase in HR.
Phase IV
With venous return restored there is an overshoot, as compensatory mechanisms continue to operate.
The increased BP causes a baroreceptor mediated bradycardia. Sympathetic increase in SVR.
Phase IV
With venous return restored there is an overshoot, as compensatory mechanisms continue to operate.
The increased BP causes a baroreceptor mediated bradycardia. Sympathetic increase in SVR.
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DIFFERENT RESPONSES
Autonomic dysfunction (e.g. autonomic neuropathy and drugs) = BP falls and remains low until the intrathoracic pressure is released.
The changes in pulse rate and overshoot are absent.
Patients with primary hyperaldosteronism have no HR changes and no BP rise when the intrathoracic pressure returns to normal.
Returns to normal when the aldosterone-secreting tumour is removed.
SQUARE WAVE RESPONSE
Seen in cardiac failure, constrictive pericarditis, cardiac tamponade and valvular heart disease.
Blood pressure rises, remains high throughout the manoeuvre, and returns to its previous level at the end.
SINUSOIDAL RESPONSE is seen in a normal patient.
Good bedside test for
autonomic dysfunction
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