Transcript Educational slidesheet - Royal College of Physicians

Acute care toolkit 12
Acute kidney injury
and intravenous fluid therapy
Definition and staging of AKI
• The term ‘acute kidney injury’ (AKI) replaces
the term ‘acute renal failure’
• Even seemingly minor changes in serum
creatinine levels are associated with a
significant increase in mortality
• AKI should be regarded as a spectrum of injury
that may progress to organ failure
Definition and staging of AKI
Causes of AKI
Risk factors for AKI
• AKI occurs most commonly in patients who are
at risk, who either are acutely ill or have had
major surgery
• Recognition of those at risk of AKI allows simple
preventative measures, eg ensuring adequate
hydration
• Patients at risk of AKI should be aware of the risk
of AKI developing in certain situations and actions
to be taken, eg temporary cessation of drugs that
may exacerbate hypovolaemia and/or
hypotension
AKI warning systems
• In March 2015, NHS England mandated that all
NHS trusts in England must have biochemistry
department laboratory systems that issue an AKI
warning, based on rises in serum creatinine level,
for patients in secondary care
• Each trust must determine how they
communicate this AKI warning to clinicians caring
for individual patients, eg e-alerts, AKI care
bundles, AKI outreach teams
Recognised risk factors for AKI
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Age >75 years
Pre-existing CKD (eGFR <60 mL/kg/1.73 m2)
Previous episode of AKI
Debility and dementia
Heart failure
Liver disease
Diabetes mellitus
Hypotension (Mean arterial pressure <65 mmHg,
systolic pressure <90 mmHg)
Sepsis
Hypovolaemia
Nephrotoxins, eg gentamicin, NSAIDs, iodinated contrast
Antihypertensives in setting of hypotension, eg ACE inhibitors,
loop diuretics
Initial investigation of AKI
• Urea and electrolytes, and creatinine
• Bicarbonate
• Full blood count – if platelets low, request blood film/
lactate dehydrogenase (to diagnose haemolytic uraemic syndrome/
thrombotic thrombocytopenic purpura)
• Liver function tests (to diagnose hepatorenal syndrome)
• Ca2+/PO43– (to diagnose myeloma)
• Creatine kinase (to diagnose myeloma)
• Blood cultures (if sepsis suspected)
• Urinalysis – if blood, protein, leucocytes or nitrites, send midstream
urine
• Ultrasound scan of renal tract and bladder
– if obstruction expected, scan within 24 h
– if pyonephrosis suspected, scan within <6 h
Management of AKI
Intravenous (IV) fluid therapy
• Any dehydrated patient is at risk of AKI,
particularly in the setting of acute illness
• For any patient who is fasting for over 12 h
or in whom losses of fluid cannot be matched
by parenteral intake, parenteral fluids must be
commenced
Assessing fluid status
Prior to any prescription of IV fluids, the patient
should have a volume assessment that includes
the following parameters
• Capillary refill
• Pulse rate
• Blood pressure (including
postural drop)
• Jugular venous pressure
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Respiratory rate
Oedema – pulmonary or peripheral
Passive leg raising test
Fluid balance chart review
Weight (trend important)
Classification of IV fluid therapy
• NICE recommends that assessment of a
patient’s fluid balance should be part of every
ward round
• It also recommends that IV fluid therapy is
classified as resuscitation, replacement or
routine maintenance, and that any
prescription should clearly identify which type
of IV fluid therapy the patient is receiving
Classification of IV fluid therapy
Initial fluid resuscitation
• NICE recommends that fluid resuscitation is best
approached with a crystalloid solution rather
than a colloid
• Moat experts would recommend a balanced
crystalloid (eg Hartmann’s, lactated Ringer’s or
Plasma-Lyte 148), because excessive amounts of
0.9% sodium chloride can result in
hyperchloraemic metabolic acidosis
• The only exception is rhabdomyolysis, when
0.9% sodium chloride would be preferred initially
because of the risk of hyperkalaemia
Algorithm for initial fluid resuscitation
Composition of IV fluids
It is important to know the electrolyte content
of fluid prescribed
IV fluid challenges
• An IV cannula of adequate size to infuse the
fluid at a high enough rate must be used
(usually at least a 20G cannula and infusion of
250–500 mL over 5–15 minutes)
• Responsiveness to the fluid challenge
should be assessed by regular monitoring of
blood pressure and pulse rate
Responding to the fluid challenge
• If there is an improvement in either blood
pressure or pulse rate that is poorly sustained,
the fluid challenge should be repeated
• If haemodynamic stability is restored and the
patient is deemed euvolaemic, the type of IV fluid
prescribed should be reviewed
• If there is no improvement after two accurately
performed fluid challenges, the patient should be
reviewed and, when appropriate, their care
should be escalated for senior review and
possible involvement of critical care
Routine maintenance IV fluids
• Rules for prescribing routine maintenance
IV fluid therapy include:
– IV fluid should be given via volumetric pump if a
patient is on fluids for over 6 h or if the fluid
contains potassium
– Always prescribe as mL/h, not ‘x hourly’ bags
– Never give maintenance fluids at more than
100 mL/h
– Never prescribe fluids for more than 24 h at a time
Routine maintenance IV fluids
Complications of AKI
Referring to a nephrologist
• Management of AKI should be discussed with a
nephrologist as soon as possible, and within 24 h of
detection when one or more of the following is present
– A possible diagnosis that may necessitate specialist
treatment (eg vasculitis, glomerulonephritis,
tubulointerstitial nephritis or myeloma)
– AKI with no clear cause
– Inadequate response to treatment
– Complications associated with AKI
– AKI stage 3
– A renal transplant
– Chronic kidney disease (CKD) stage 4 or 5
Patient recovery
• Patients recovering from a significant episode of
AKI may develop profound diuresis, resulting in a
free water deficit, hypernatraemia and/or
hypokalaemia
• During this phase, maintaining patient hydration
and replacing electrolytes are of paramount
importance
• Accurate fluid balance with daily weights is very
important to prevent patients from becoming
dehydrated as they recover from AKI
Discharge planning
• Patients who have had AKI are at risk of developing CKD in the long
term (this risk depends on the severity of the episode of AKI)
• Patients’ kidney function should be checked prior to discharge
• Refer patients to nephrology if they are discharged with an eGFR
<30 mL/min/1.73 m2
• Medications should be reviewed prior to discharge, with a plan to
reintroduce medications that may have been held during the acute
illness (this may require an early follow-up with the patient’s GP)
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severity of AKI
cause of AKI
risk factors for AKI
kidney function on discharge
advice on whether medications need to be reviewed or reintroduced
Educational resources
• An app developed by the Royal College of
Physicians of Edinburgh that is free to download
www.rcpe.ac.uk/policy-standards/acute-kidney-injury-app
• An AKI core competency framework for
healthcare professionals, endorsed by the
Academy of Medical Royal Colleges
www.aomrc.org.uk/doc_details/9503-acute-kidney-injury-acompetency-framework
• The RRAPID app and e-book, which contain an
AKI risk calculator and a NEWS calculator
http://rrapid.leeds.ac.uk
The RCP produces a series of acute care toolkits
on a range of topics including
• Handover
• Ambulatory emergency care
• Teaching on the acute medical unit • Sepsis
• Acute oncology on the acute
• Acute medical care for frail older
medical unit
people
All the toolkits, including the full version of Acute toolkit 12: Acute
kidney injury and intravenous fluid therapy, can be accessed at
www.rcplondon.ac.uk/resources/acute-care-toolkits