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Support of Renal Function 501

number of publications provide clinically-focused out- understanding of how the kidneys function and indeed
lines of nursing management for the CRRT technique and fail at a cellular level is continuing to evolve. There are a
patient care. 54,106 Additional information for the specific variety of illnesses and clinical events that result in acute
equipment and products used by an individual ICU are renal failure. An artificial process is able to achieve kidney
also necessary. This would include components such as function and replacement, and in the acute setting this is
size and type of membranes used, access catheters, fluids achieved with CRRT, different from that used in chronic
(bicarbonate and lactate) and additives. cases. There are several options for this support process in
the ICU, and much of what is done evolved out of dialysis
SUMMARY developments that originated in the 1940s. Nursing man-
agement of these therapies is an exciting and important
Acute renal failure is a common complication associated role for the intensive care nurse, with limited evidence to
with critical illness. The human kidneys may appear to guide practice. This chapter, outlining renal physiology,
perform simple functions of blood filtration or cleansing, pathology, illness and disease with the development and
but they are complex organs with additional functions use of the artificial kidney, aims to encourage nurses to
related to the endocrine and immune systems. An further develop this area of nursing practice in the ICU.

Case study
Andrew Citizen, a 36-year-old man, 180 cm in height and weighing tense and swollen. The surgeon insisted on a CT scan to further
112 kg, was admitted to the ICU from a regional hospital 36 hours assess the abdomen. After some discussion it was finally agreed
after undergoing a laparoscopic cholecystectomy, then a subse- and arranged for 2 hours later. The CVVHDf was ceased and
quent laparotomy and closure of a bowel perforation and leaking Mr Citizen was prepared for transport. During the CT, his condition
bile duct 18 hours later. Since this procedure he had complained deteriorated; he became febrile, required increasing inotropes to
of increasing abdominal pain, rigidity and guarding, fever up to maintain his BP, and his FiO 2 was increased. His conscious state
39.4°C, elevated WCC, increasing difficulty breathing, restlessness appeared to also deteriorate, although this was hard to assess as
and confusion. His urine output had dropped below 0.5 mL/kg/h he was sedated for transport. Large intra-abdominal fluid collec-
for several hours. tions were noted on the CT. The surgeon was keen to re-explore
the abdomen, but ICU staff remained concerned about Mr Citizen’s
On admission to the ICU, he was intubated and ventilated (stan-
dard procedure for the Royal Flying Doctor Service transport of unstable condition. CVVHDf recommenced, and Mr Citizen again
the critically ill), warm, tachycardic (124 beats/min), hypotensive improved after some hours.
(85/50 mmHg), heavily sedated and unresponsive to commands, Mr Citizen remained stable 48 hours later, on SIMV FiO 2 0.4, 5 cm
and oliguric. Given the history and presenting symptoms, he was PEEP, mildly febrile, low-dose noradrenaline, haemodynamics con-
diagnosed with postprocedural sepsis secondary to bowel perfora- sistent but mildly elevated. It was decided to electively cease CRRT
tion. He was acidotic (pH 7.29) with a lactate of 3.5 mmol/L, uraemic and insert a urinary catheter to assess renal function.
(13.5 mmol/L), and had a creatinine level of 205 mmol/L. Mr Citizen’s condition remained reasonably stable, although oligu-
After initial assessment the following therapy was prescribed: ria persisted and his temperature again rose. It was agreed that the
● broad-spectrum antibiotic cover; already commenced but patient should return to theatre to drain fluid accumulations 12
adjusted hours after stopping the infusion.
● continuing ventilatory support, lightening sedation to better On return from theatre, Mr Citizen was again haemodynamically
assess neurological status unstable, hypothermic and anuric. Fluid challenges were ordered,
● change of CVC line, insertion of PA catheter and arterial line, inotropes increased and CVVHDf recommenced on the previous
and assessment of cardiac output and haemodynamic profile regimen. The patient staged a minor recovery, but early in the
● administration of boluses of 0.9% saline to restore circulating treatment cycle, intermittent flow difficulties were experienced
fluid deficit from the subclavian vascath, and 4 hours later the circuit clotted.
● commencing noradrenaline infusion at low dose until haemo-
dynamic profile improved A new femoral vascath was inserted, CRRT was recommenced
● surgical consult with a heparin infusion at 8 U/kg/h. The patient was stabilised
● commencing CVVHDf if no response to fluid and inotropes post procedure. He was weaned from inotropes over the next 24
● blood cultures. hours and moved onto CPAP. His urine output returned over the
next 2 days, with the CRRT circuits clotting approximately every
Mr Citizen’s oliguria persisted despite restoration of a satisfactory 24 hours.
MAP with inotropes and fluid administration, and his serum creati-
nine levels continued to rise. CVVHDf was started at 30 mL/kg/hr With a return of urine function and output at 0.5 mL/kg, and failure
with predilution fluid replacement. No anticoagulant was adminis- of the next circuit due to clotting, CRRT was not recommenced.
tered. Two hours later, the patient’s temperature fell to 37.8°C, hae- Fluids were restricted and recovery occurred over the next days.
modynamics improved and the FiO 2 could be weaned from 0.8 to Mr Citizen’s urea level fell from a high of 19.9 mmol/L to
0.6 over the next 6 hours, and PEEP decreased to 5 cmH 2 O. 11.5 mmol/L, his creatinine returned to 150 mmol/L and he was
now experiencing post-ARF polyuria in excess of 100 mL/h. His
Mr Citizen’s conscious state improved, and his condition continued condition continued to improve and he was discharged from ICU
to stabilise over the next 12 hours, although his abdomen remained 24 hours later.