Group 2: Standard breathing command
–20 mmHg), inferior vena cava
CAVITY
The control group had to follow a standard automated breathing command telling the patient just shortly before the scan started “Please breathe in and hold your breath” and after completion of the scan “Continue breathing.”The applied approach and complex physiological implications are summarized in Fig. Mueller maneuver and standard breathing command: During the Mueller maneuver (left image), the patient sucks on the device, which allows a defined negative pressure (–20 mmHg). This causes the inferior vena cava to be compressed by the diaphragm due to breathing resistance. At the same time, there is a clear increase in the flow of the superior vena cava, which clearly concentrates the bolus of contrast medium, which is coming from the superior vena cava. Due to the lack of inflow of uncontrasted blood from the inferior vena cava, it reliably prevents a transient interruption (TIC) and concentrates the contrast bolus. During inspiration in the picture on the right, there is often a reverse flow behavior with an increase in the size of the inferior vena cava and an increased inflow of non-contrasted blood from the abdominal cavity. This often leads to the TIC phenomenon [