Question 11#

To obtain the MOST accurate intravesicular bladder pressure readings, the following must be true: 

A. The head of bed must be 45°, with the transducer at the axillary line and 50 mL of saline instillation

Correct Answer: B

To obtain accurate IAP measurements, the needed steps must be performed correctly. The patient must be pharmacologically paralyzed, therefore preventing abdominal contractions. The patient must be completely supine, with the IAP transducer leveled at the mid-axillary line. This usually correlates at the level of the iliac crests. It is important to obtain multiple readings at the time of measurement and wait at least 30 to 60 seconds after instillation of room temperature of saline as cold fluids cause detrusor contractions. A maximum of 25 mL of sterile saline should be used as larger amounts will falsely elevate IAP. 

References:

1. McBeth PB, Zygun DA, Widder S, et al. Effect of patient positioning on intra-abdominal pressure monitoring. Am J Surg. 2007;193:644-647.
2. De Waele J, Pletinckx P, Blot S, Hoste E. Saline volume in transvesical intra-abdominal pressure measurement: enough is enough. Intensive Care Med. 2006;32:455-459.
3. Chiumello D, Tallarini F, Chierichetti M, et al. The effect of different volumes and temperatures of saline on the bladder pressure measurement in critically ill patients. Crit Care. 2007;11:R82. 

Question 12#

A 66-year-old male presents to the emergency department with hypotension and severe abdominal and back pain. He was found to have a ruptured abdominal aortic aneurysm, and the massive transfusion protocol was initiated. He is now s/p EVAR in the ICU. The nurse notifies you that his urine output continues to decline.

Which laboratory and/or examination finding is the MOST suggestive of ACS?

A. Abdominal distension with bladder pressure of 25 cm H₂O, increasing oxygen requirements

Correct Answer: A

ACS encompasses an increased IAP in conjunction with the presence of end-organ dysfunction notably decreased renal function, decreased pulmonary function, and reduced preload. Typically, urine sodium in ACS is reduced in addition to decreased mixed venous saturation, which correspond to the reduced cardiac output. Cardiac ultrasound should correspond with hypovolemia in the setting of ACS, but a significant drop of hemoglobin complicates the picture as the patient has ongoing bleeding. Therefore, the best answer is A.

References:

1. Malbrain ML, De Iaet IE. Intra-abdominal hypertension: evolving concepts. Clin Chest Med. 2009;30(1):45-70.
2. Ke L, Tong Z, Ni H, et al. The effect of intra-abdominal hypertension incorporating severe acute pancreatitis in a porcine model. PLoS One. 2012;7(3):e33125. doi:10.1371/journal.pone.0033125.