Physiological changes in valsalva maneuver
Valsalva maneuver
- Forced expiration against a closed glottis
Stage 1
- Due to forceful expiration against closed glottis intrathoracic pressure increase
- Initially increase thoracic pressure transmit to aorta and increase blood pressure
Stage 2
- Later increase intrathoracic pressure causes reduction of venous return
- End diastolic volume reduces
- Stroke volume reduces
- Cardiac output reduces ( CO = SV × HR)
- Blood pressure reduces (BP = CO × TPR)
Stage 3
- Reduction of blood pressure reduces the discharge rate of barorecptor
- Reduce inhibition of sympathetic discharge
- Increase sympathetic discharge
- It increases heart rate ( tachycardia ) and total peripheral resistance
Stage 4
- Glottis open
- Intrathoracic pressure return to normal
- Venous return restored
- Cardiac output restored
- But peripheral vessel remains constricted ( TPR remains constant)
- Blood pressure rises above normal
Stage 5
- Increase blood pressure cause increase discharge rate of baroreceptor
- Increase inhibition on sympathetic discharge
- Heart rate reduces (bradycardia )
- Blood pressure drop to normal level
Labels: CVS, CVS SEQs, Physiology SEQ