The diagnosis of abdominal compartment syndrome was made if the urinary bladder pressure reading was > 25 mm Hg.

Factors associated with development of the abdominal compartment syndrome:

(1) peak airway pressure in mm Hg

(2) fluid balance in liters (positive indicates more fluid input) at 24 hours

probability of developing the abdominal compartment syndrome =

= 1 / (1 + EXP((-1) * z))

z based on peak airway pressure and 24 hour fluid balance =

= (-18.6763) + (0.1671 * (peak airway pressure in mm Hg)) + (0.0009 * (24 hour fluid balance in mL)) =

= (-18.6763) + (0.1671 * (peak airway pressure in mm Hg)) + (0.9 * (24 hour fluid balance in L))

where:

• According to an example on page 135, a PAP of 57 mm Hg and 12 liters net fluid balance should have a 100% chance of developing ACS. I can only get 84%.

• Using liters of fluid with 0.0009 gives results discrepant with the examples given.

A second equation for probability estimation was given (page 136) for situations where the peak airway pressure was a consequence and not causative for the ACS:

z =

= (-6.7291) + (0.005 * (24 hour fluid balance))

There are a number of problems with the second equation version:

(1) If we assume that the fluid balance is in mL, then the equation give values that do not match results given in the examples.

(2) If we assume that it should be 0.0005 for mL and 0.5 for L, then we get a 68% probability at 15 liters fluid balance, which is close to the value given on page 136. However, at 8 liters we get 7% rather than the stated value of 0.7% given in the preceding example (7% seems to me more likely to be a reasonable estimate).

Limitations:

• The authors stress that the equations should not be used in place of clinical judgment, and that any patient suspected of having intra-abdominal hypertension with ACS should quickly undergo decompression.