Valsalva Manoeuvre | Lecture Note

University:
The University Of Western Ontario
Course:
ANAT 2200B | Systemic Anatomy of the Human Body
Academic year:

2022
Views:

455

Pages:

3
Author:

Kyuwon J.

Valsalva manoeuvre ● Forced expiratory effort on closed glottitis ○ against fixed resistance ○ production of sustained rise ■ intrathoracic pressure ■ transiently alters venous return ● cardiac output impact ● atrial pressure ● autonomic tones ○ “bearing down” ■ straining at stool ○ heavy lifting ○ coughing fits ○ blowing hard into syringe Core Physiology ● Phase 1 ○ onset of strains ■ intrathoracic pressure increases ■ Aorta physically compressed ⇒ increase in atrial pressure for few seconds ■ bradycardial reflex ● Baroreceptor response may happnen transiently ● Phase 2 ○ maintaining strains ■ reduction of venous return ■ impeded venous returns on right heart ■ ■ ■ ■ ■ decrease in RV preloads short delay decrease in preloads decreased stroke volume (cardiac output) Arterial pressure falls ● early second phase ■ baroreceptor sense fall ⇒ sympathetic activation ● increase in HR ● increase in contractility and systemic vasoconstriction ■ compensation ⇒ BP will partially recover (may or maynot) ● despite low preload rates ● Phase 3 ○ release of strains ■ pressure suddenly drops to normal pressure ■ Aortic compression halts ⇒ future drop in arterial pressure ■ short tachycardic response ● sympathetic tone elevated ● phase 4 ○ overshoot ■ seconds after release ■ venous return surges ⇒ LV filling improved ○ residual sympathetics ■ stroke volume increases ■ afterloads ○ Arterial pressure increases over baseline ○ Barireceptor-mediated reflex bradycardia will follow Clinical significance ● Bedside cardiovascular exam ○ LV volume during stains ■ hypertonic cardiomyopathy ⇒ murmur increases ■ Aortic stenosis ⇒ murmur decreases ■ mitral valve prolapses ● click occurs earlier ● murmur will get louder and longer