Valsalva maneuver

The Valsalva maneuver is forced expiration against a closed airway, raising pressure in the chest and abdomen. It changes venous return, heart rate, and blood pressure in predictable phases.

Intrathoracic pressure: The pressure within the chest cavity, which varies with breathing and can rise sharply during straining. The maneuver works by raising pressure around the heart and major blood vessels.
Valsalva maneuver for supraventricular tachycardia: A modified straining technique used to stop certain episodes of supraventricular tachycardia. The maneuver can interrupt reentrant electrical circuits in the heart.
Glottis: The opening between the vocal folds, which can close to block airflow from the lungs. Closing the glottis creates the sealed airway against which expiration is forced.
Müller maneuver: A forceful inspiratory effort against a closed airway that lowers pressure in the chest. It reverses the direction of respiratory effort and intrathoracic pressure change.
Venous return: The flow of blood returning to the heart through the veins. High chest pressure temporarily impedes blood returning to the heart.
Modified Valsalva maneuver: A version that adds repositioning after strain to improve conversion of supraventricular tachycardia. Lying back and raising the legs after straining can strengthen the vagal response.
Diaphragm: The dome-shaped muscle separating the chest cavity from the abdomen and driving most quiet breathing. Expiratory effort recruits the diaphragm and abdominal muscles to raise internal pressure.
Cough: A reflex or voluntary burst of airflow that clears irritants from the airways. A cough briefly closes the glottis but releases air explosively rather than sustaining a closed-airway strain.
Baroreflex: A feedback response in which pressure sensors adjust heart rate and vascular tone to stabilize blood pressure. Pressure changes during and after straining trigger reflex shifts in heart rate.
Valsalva retinopathy: A retinal hemorrhage caused by a sudden rise in venous pressure after straining. The maneuver can rupture small retinal vessels in susceptible circumstances.

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