A change of 1 mmHg is typically used to define changes in intra-abdominal pressure (IAP)

a change of 1 mmHg is typically used to define changes in intra-abdominal pressure (IAP), not transpulmonary pressure (TPP).

Intra-abdominal pressure is the pressure within the abdominal cavity, while transpulmonary pressure is the pressure difference between the alveoli (air sacs) in the lungs and the pleural space (the space between the lungs and chest wall).

For intra-abdominal pressure monitoring, a change of 1 mmHg is commonly used as a threshold for detecting significant changes in IAP. For example, an increase in IAP of 1 mmHg or more can indicate the development of abdominal compartment syndrome, which can have significant implications for patient management and outcomes.

Transpulmonary pressure, on the other hand, is typically measured using esophageal balloon catheters or other specialized techniques, and the threshold for significant changes in TPP may vary depending on the specific measurement method used.

So, while both IAP and TPP are measures of pressure, the thresholds for defining significant changes in these pressures may differ based on the specific measurement method and clinical context.