Kussmaul's sign

Kussmaul's sign is a medical observation where, during inhalation, instead of the usual decrease in pressure inside the veins near the heart, there is a paradoxical increase. This is often linked to severe heart or lung conditions that cause the right side of the heart to struggle with filling properly. When trying to breathe in, the abnormal pressure change prevents blood from flowing smoothly into the heart, leading to a noticeable rise in neck vein swelling. It's a useful sign for doctors to identify underlying issues affecting heart function or fluid balance.