NU656 Unit 8 AKI From Abdominal Compartment Syndrome Example

The Kidneys Were Being Squeezed: An Acute Kidney Injury Case of Abdominal Compartment Syndrome on Day Two of Severe Acute Pancreatitis in a 58-Year-Old Man

[Student Name]

Purdue University Global

NU656: AGACNP Critical Care Management

Unit 8 Acute Kidney Injury Case

[Instructor Name]

[Date]

The patient is composite; values, volumes and times are bracketed.

The Case

Mr. [D.] is a [58]-year-old man admitted [40] hours ago with severe acute pancreatitis after heavy alcohol use. He weighs [74] kg. His baseline creatinine, measured at a clinic visit [three] months ago, was [1.0] mg/dL. In the first [24] hours he received [nine] liters of crystalloid for tachycardia and a falling blood pressure. He is now intubated for worsening oxygenation and sedated.

The values that prompted this case appear below, baseline or admission first and current second.

1. Creatinine: [1.0] at baseline and [2.3] mg/dL now.

2. Urine output: [260] mL over the last [14] hours, an average of [0.25] mL/kg per hour.

3. Potassium: [4.2] and [5.4] mEq/L.

4. Bicarbonate: [23] and [18] mEq/L.

5. Mean arterial pressure: [72] mmHg on norepinephrine [0.10] mcg/kg per minute.

6. Peak airway pressure: [24] rising to [36] cm H2O over [eight] hours, with an unchanged tidal volume.

7. Abdomen: distended and tense; bladder pressure [24] mmHg, measured at end-expiration in the supine position.

Staging the Injury

KDIGO defines acute kidney injury by a rise in serum creatinine or a fall in urine output and grades it by whichever criterion gives the higher stage (Khwaja, 2012). Both criteria are worked here.

Creatinine: 2.3 / 1.0 = [2.3] times baseline. A rise to 2.0 to 2.9 times baseline is stage 2.

Urine output: an hourly rate under half a milliliter per kilogram sustained for at least 12 hours is stage 2; a rate under 0.3 sustained for a full day, or anuria lasting 12 hours, is stage 3. His output of [0.25] mL/kg per hour has lasted [14] hours, which is stage 2 now and will be stage 3 if it continues for another [10] hours.

He therefore has stage 2 acute kidney injury, on a trajectory toward stage 3. The urine output line is the one to watch, because it will cross into stage 3 before the creatinine does.

Finding the Cause

The usual causes of kidney injury in a critically ill patient were considered in order. Hypovolemia was unlikely after nine liters, with a positive balance of more than [seven] liters and edema in the flanks. Sepsis was possible but not supported: he had no fever above [38.1] C and no source on imaging. Nephrotoxins were reviewed; he had received one dose of contrast on admission for a CT scan and no aminoglycosides or anti-inflammatory drugs. Contrast alone would not explain a tense abdomen and rising airway pressures.

The 2013 consensus of the abdominal compartment society defines intra-abdominal hypertension as a sustained pressure of 12 mmHg or more, graded I at 12 to 15, II at 16 to 20, III at 21 to 25 and IV above 25. Abdominal compartment syndrome is a sustained pressure above 20 mmHg with new organ dysfunction (Kirkpatrick et al., 2013). His bladder pressure of [24] is grade III, and the kidneys and lungs are both failing. The diagnosis is abdominal compartment syndrome.

The abdominal perfusion pressure, mean arterial pressure minus intra-abdominal pressure, explains the kidneys. 72 minus 24 = [48] mmHg, below the level of about 60 at which organ perfusion is usually considered adequate. Pressure on the renal veins and parenchyma also reduces filtration directly. Pancreatic inflammation, a swollen bowel and large-volume resuscitation all raised the pressure, and the fluid given to protect the kidneys has become one of the forces injuring them.

Management, Ordered by Effect

The guideline sets out medical steps first and surgical decompression when they fail (Kirkpatrick et al., 2013). The plan follows that order with a clock.

1. Stop adding fluid. Further boluses are withheld, and maintenance fluid is cut to the minimum needed for medications. The guideline suggests avoiding a sustained positive balance once initial resuscitation is complete.

2. Improve abdominal wall compliance. Sedation and analgesia are deepened, and the head of the bed is kept below [30] degrees while pressures are measured. A trial of neuromuscular blockade is started, since relaxing the abdominal muscles can lower the pressure quickly.

3. Empty the gut. A nasogastric tube on suction and a rectal tube are placed to reduce the volume inside the bowel.

4. Drain free fluid. Ultrasound shows a moderate amount of fluid around the pancreas and in the abdomen; interventional radiology is asked to place a percutaneous drain, which the guideline suggests when free fluid is present, since it can avoid an operation.

5. Recheck. Bladder pressure is measured every [four] hours. If it stays above 20 mmHg with worsening organ function after [six] hours of these measures, the surgical team will be asked about decompressive laparotomy.

At [six] hours after the drain was placed and [1.4] liters removed, the bladder pressure was [16] mmHg and the peak airway pressure had fallen to [28]. Urine output rose to [0.6] mL/kg per hour over the next [four] hours.

The measurement itself needs care if the numbers are to be trusted. The bladder is instilled with no more than [25] mL of sterile saline, the transducer is zeroed where the midaxillary line meets the iliac crest, and the reading is taken at the end of expiration with the patient flat and without active abdominal muscle contraction. The bedside nurses were shown the method on the first reading, and each value is charted with the position and the sedation level at the time, so that a change in the number reflects the abdomen and not the technique. A reading taken with the head of the bed raised can overstate the pressure by several millimeters of mercury and lead the team toward an operation the patient does not need.

When Renal Replacement Therapy Would Start

Dialysis is not started simply because the creatinine has doubled. In the STARRT-AKI trial, starting renal replacement therapy early in critically ill adults with severe kidney injury did not reduce 90-day mortality and was associated with more patients remaining dependent on dialysis at 90 days than a standard strategy of waiting for a clear indication (STARRT-AKI Investigators, 2020). For this patient the triggers are stated in advance: potassium above [6.0] mEq/L despite treatment, pH below [7.15], fluid overload that impairs oxygenation after the abdomen has been decompressed, or oliguria persisting beyond [72] hours. If he needs it, continuous therapy will be chosen because his pressure depends on norepinephrine, and it will also allow fluid to be removed slowly.

The case teaches a single point that applies beyond pancreatitis: when a patient's kidneys fail after large-volume resuscitation and the abdomen is tense, the bladder pressure should be measured before any more fluid is given.

References

Khwaja, A. (2012). KDIGO clinical practice guidelines for acute kidney injury. Nephron Clinical Practice, 120(4), c179-c184. https://doi.org/10.1159/000339789

Kirkpatrick, A. W., Roberts, D. J., De Waele, J., Jaeschke, R., Malbrain, M. L. N. G., De Keulenaer, B., Duchesne, J., Bjorck, M., Leppaniemi, A., Ejike, J. C., Sugrue, M., Cheatham, M., Ivatury, R., Ball, C. G., Reintam Blaser, A., Regli, A., Balogh, Z. J., D'Amours, S., Debergh, D., . . . Olvera, C. (2013). Intra-abdominal hypertension and the abdominal compartment syndrome: Updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome. Intensive Care Medicine, 39(7), 1190-1206. https://doi.org/10.1007/s00134-013-2906-z

STARRT-AKI Investigators. (2020). Timing of initiation of renal-replacement therapy in acute kidney injury. New England Journal of Medicine, 383(3), 240-251. https://doi.org/10.1056/NEJMoa2000741