Utilizing Ultrasound to Visualize the Generation of 40 mm Hg Intrathoracic Pressure for the Valsalva Maneuver

We recruited healthy volunteers to participate in the study. We first obtained an image of the subject's right IJV at the level of the laryngeal prominence, pre-valsava using a linear ultrasound probe. We measured the anterior posterior diameter of the IJV at rest (minimum diameter) and subsequently when achieving 40mmHg while exhaling into a manometer (maximum diameter). We also collected subjects' duration of valsalva.

The first line treatment of supraventricular tachycardia has been vagal maneuvers in hemodynamically stable patients. Various methods have been demonstrated to generate the standard 40mmHg of intrathoracic pressure for 10 seconds while performing the valsalva maneuver. These methods include asking patients to valsalva while measuring pressures with a manometer or to move the plunger by blowing into an empty 10cc syringe. During clinical practice, it is often difficult to assess the adequacy of the valsalva maneuver as manometers are not readily available and patients often struggle to follow instructions when exhaling through a syringe. The objective of this study was to assess if we can utilize the visualization of the internal jugular vein (IJV) on ultrasound as a surrogate for generating an adequate valsalva.

A total of 19 healthy adult volunteers were enrolled. 15 out of 19 participants (78.9%) successfully achieved and maintained manometer pressure 40 mmHg for a minimum of 10 seconds. Four participants were excluded from analysis as three were unable to maintain valsalva for 10 seconds and one did not achieve 40mmHg during valsalva. Among the included participants, their mean internal jugular vein diameter increased from 0.15cm (SD 0.07) at baseline to 1.35cm (SD 0.25) after valsalva. The mean paired difference was 1.20 cm (p

POCUS reliably detects IJV distension during valsalva maneuver in healthy adults. Study findings suggest feasibility of using ultrasound to objectively measure valsalva effort when manometers are not readily available. Further studies in the Emergency Department in patients with supraventricular tachycardia are needed to evaluate clinical utility as this study includes healthy volunteers. Additionally, only volunteers with adequate valsalva were included in paired analysis with a single operator for measurements that may introduce selection bias and inter-operator variability.