Intra-abdominal pressure, or IAP for short and in medical terminology, refers to a respiratory pressure that is present within the abdominal cavity. In a healthy person, this pressure is approximately a measured value of 0 to 5 mmHg. If the intra-abdominal pressure is too high, the arterial blood flow may be weakened.
What is intraabdominal pressure?
In specialist medicine, IAP is the pressure that prevails inside the abdominal cavity. In specialist medicine, the IAP is understood to be the pressure that prevails inside the abdominal cavity. This pressure is measured at the end of the respiratory cycle (expiration) in millimeters of mercury column (mmHg for short). In a healthy adult person, this pressure is normally between 0 and 5 mmHg. If the value is above 5, medicine speaks of a slightly elevated value, although this does not always have to be harmful to health. Only when the value exceeds 12 mmHg and lasts for more than twelve hours is it generally referred to as an elevated intra-abdominal pressure that poses a health risk. However, a very high IAP or one that remains elevated for a long time can have a negative effect on blood circulation. The result can be malfunctions or even damage to the abdominal organs. If, on the other hand, the intra-abdominal pressure remains above 20 mmHg for too long, there may even be a noticeable decrease in arterial blood flow. This primarily affects the abdominal organs but also, in some cases, venous return to the heart.
Function and task
Intra-abdominal pressure is the pressure that permanently prevails in the abdominal cavity of humans (and also of many other vertebrates). This pressure is measured with the patient in the flat position. In a healthy person, this value should normally be below 5 mmHg. However, various diseases can cause the pressure to rise permanently to as much as 7 mmHg, without there being any direct mention of a health burden on the body from a medical point of view. The level of intra-abdominal pressure depends on the patient’s breathing and physical condition. But what is the role of intra-abdominal pressure in the body? Various studies show that intra-abdominal pressure increases during physical exertion, such as lifting heavy loads. This relieves the organs, but also the spine and the intervertebral discs. In this case, the rising pressure thus acts like a shock absorber that acts inside the body. Furthermore, intra-abdominal pressure supports things like digestion – even if only indirectly. This is because sports exercises, such as abdominal exercises, that increase intra-abdominal pressure have been shown to make the rectum work more effectively when a minimally increased pressure is applied to it. But in turn, the internal organs, spine and even the intervertebral discs can also be damaged or impaired in function if the pressure is too high and lasts too long. While optimal or normal intra-abdominal pressure ensures that the organs are not supplied with too much blood, too much pressure quickly ensures that they are undersupplied. In addition, intra-abdominal pressure also triggers pressure on the organs – which in turn can lead to organ damage or dysfunction if the elevated IAP persists for too long.
Diseases and medical conditions
In a healthy adult, intra-abdominal pressure is approximately between a value of 0 and 5 mmHg. However, some diseases can cause the pressure to rise to a value of up to 7 mmHg, even in normal conditions. In addition, medicine only speaks of a value of at least 12 mmHg as being of concern to health. Intra-abdominal pressure can rise for a variety of reasons. A common one, for example, is physical stress, as can occur during sports or lifting. But intra-abdominal pressure can also rise due to various diseases or injury. Common causes of increasing or elevated intra-abdominal pressure are injuries such as abdominal trauma, an abscess in the abdomen, a mesenteric infarction (also called an intestinal infarction), an accumulation of air in the abdominal cavity (technically called pneumoperitoneum), an obstruction of the bowel (called ileus), or bleeding in the abdomen.Injuries and diseases such as these can usually also be diagnosed or ruled out by measuring the intra-abdominal pressure. The IAP is measured in the flat position via the urethra. The urinary bladder must be empty for this. In the case of increased intra-abdominal pressure, a distinction is made between four stages: Grade I to IV. Medicine speaks of increased Grade I pressure when the value is between 12 and 15 mmHg. Grade II is spoken of when the value is between 16 and 20 mmHg. Grade III refers to an intra-abdominal pressure that ranges between 21 and 25 mmHg. Grade IV, on the other hand, refers to an elevated pressure that is higher than 25 mmHg. Severe adverse health effects can occur at pressures above 20 mmHg. For example, abdominal compartment syndrome can develop. This means that the pressure inside the abdomen causes blood flow to the organs to be reduced.
