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Acute Kidney Injury

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Mind map: Acute kidney injury

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Acute Kidney Injury

Pathophysiology
- Definition
  - Abrupt deterioration in renal function
    - Reversible
  - Uraemia usually present
  - Oliguria may be present
- Medical ER
  - Distinguish Between AKI and CKD
    - RIFLE Criteria
      - Risk
        SCr x 1.5 within 48 hrs
      - Injury
        SCr x2-3
      - Failure
        SCr x3 or SCr >350um
      - Loss
        Persistent AKI >4 Wks
      - ESKD
        Persistent Renal Failure > 3Months
- Classifications
  - Pre-renal Uraemia
    - Pathology
      - Impaired Perfusion of kidneys with Blood
        Hypovolaemia
        Hypotension
        Cardiac Pump Failure
        Vascular Disase
        Kidney Damage
    - Investigations
      - Specific Gravity
        >1.02
      - Urine Osmolality
        >500
      - Urine Na
        <20
    - Management
      - Fluids
        If Peripheral Oedema
        Suspect Intrinsic
      - Manage Cause E.g. HF
  - Renal
    - Acute Tubular Necrosis
      - Causes
        Ischaemia
        Haemorrhage
        MI
        HF
        Burns
        Diarrhoea & Vomiting
        Fluid Loss
        Pacreatitis
        Diuretics
        Pregnancy
        Abrupt Placenta
        Pre-eclampisa / Eclampsia
        Drugs
        Endotoxic Shock
        Radiological Contrasts
        Rabdomyolysis
        Liver disease
        Cholestasis
      - Pathogenesis
        Intrarenal microvascular Vasoconstriction
        Increased
        Endothelin
        Adenosine
        Thromboxane A2
        Leukotrienes
        Sympathetic Nerve activity
        Vadodilation is impaired
        Tubular Cell Injury
        Ischaemia
        Tubular Cell Reovery
        eGFR is reduced
        Glomerular Contraction
        'Back leak'
        Tubular Obstruction
        Debris shed from Ischaemic tubular cells
        Course
        Oliguria - common in early stages
        Renal Function recovers after 7-21 days
        May be delayed by sepsis
        GFR may remain low
        Urine Output may increase
        Non-Oliguric AKI - less severe renal insult
        May last up to 6 wks
    - Causes
      - Vasculitis
      - Malignant HTN
      - Cholesterol Embolism
      - Haemolytic Uraemic Syndrome
      - Thrombotic thrombocytopenic Purpura
      - Pre-Eclampsia
      - Drugs
        Sulphonamide
        Chemotherapy
        Rapid Lysis of certain tumors
      - Pyelonephritis
        Suppurative
  - Post-Renal Uraemia
    - Urinary Obstruction
      - Pathophysiology
        Causes
        Lumen
        Calculus
        Blood Clots
        Tumor
        Renal Pelvis
        Ureter bladder
        Sloughed Papilla
        Within the wall
        Pelviureteric neuromuscular dysfunction
        Stricture
        Ureteric
        Ureterovesical
        Urethral
        Congenital
        Bladder neck Obstruction
        Megaureter
        Neuropathic Bladder
        Pressure from Outside
        Reteroperitoneal Fibrosis
        sclerosis with myofibroblasts
        Perivascular Infiltrates
        Malaise, Low back pain, Nausea & Vomiting
        Claudication and Haematuria
        Anaemia, Uraemia, ESR & CRP high
        CT
        Mass
        Lymph Nodes
        Tumor
        Hydronephrosis
        Progressive Rise in lumenial Pressure
        Compression and Thinning of Renal Parenchyma
        Small Kidneys
        Obstruction
        Renal Arterial vasodilation
        Vasoconstriction (Ang-II)
        Ischaemic Interstitial Damage
      - Clinical Feature
        Symptoms
        Upper Obstruction
        Loin Pain
        Dull/Sharp
        Constant/Intermittent
        Provoked
        Fluid Intake
        Diuretics
        Inc. Alcohol
        Anuria
        Bilateral Obstruction
        Complete Obstruction of 1 kidney
        Polyuria
        Partial obstruction: Impaired renal tubular concentration ability
        Intermittent Polyuria and Anuria
        Intermittent complete Obstruction
        Bladder outflow obstruction
        Hesitancy
        Narrowing and Diminished force of stream
        Terminal Dribbling
        Sense of incomplete bladder emptying
        Infection - very common
        Frequency
        Urgency
        Urge Incontinence
        Cloudy Urine
        Dysuria
        Infection
        Malaise
        Fever
        Septicaemia
        Signs
        Loin tenderness
        Enlarged Hydronephrotic Kidney
        Enlarged Bladder
        Felt
        Percussion
        Examine
        Genitalia
        Rectum
        Prostate
      - Investigations
        Bloods
        SCr or Ureaemia
        HyperKalaemia
        Anaemia
        Urine
        Haematuria
        Abdo X-ray
        Radiolucent stones/Calcifications
        CT scan
        Ultrasonography
        Upper dilation
        Stones are missed
        Excretion Urography
        Nephrogram delayed on obstructed side
        Antegrade Pyelography & Ureterography
        Defins site of Obstruction
        If cant be carried out...Retrograde Uterography
        Cystoscopy, Urethroscopy & Urethrography
      - Treatment
        Aims:
        Relieve Obstruction
        Rx cause
        Prevent/Rx Infection
        Nephrostomy
        Drainage of Urine Externally
        Urgent relief required for recent, complete upper tract Obstruction
        No immediate surgery if spontaneous relief expected
        Surgery
        DIALYSIS may be required Pre-op
        Post-Op diuresis
        Self-limiting
        Severe Na and WATER depletion
        Replace
        Peviureteric Junction Obstruction
        Disturbance of peristalsis of collecting system
        Open/Percutaneous Pyeloplasty
        Nephrectomy
        Pyonephrosis
        Septicaemia
        Obstructive Megaureter
        Defective peristalsis of lower end of ureter adjacent to ureterovesical junction
        UTI/ Flank Pain or Haematuria
        Excision of abnormal ureter w/ reimplantation into bladder
        RPF
        Ureterolysis
        Biopsy
        Lympoha/Carcinoma
        W/ CORTICOSTEROIRD
        Rely on steroids and do 1 side in bilateral Obstruction
        Regression of Fibrous Tissue
        Stents w/ steroids
        Need changing frequently
        Monitoring
        ESR & CRP
        PET Scan
Clinical Features
- Symptoms of Uraemia
  - Anorexia
  - Nausea & Vomiting
  - Pruritus
    - Intellectual Clouding
  - Drowsiness
  - Fits
  - Coma
  - Haemorrhagic Episodes
    - Epistaxis
    - Gastrointestinal Haemorrhages
- Severe Infection
Investigations
- Metabolic Acidosis
  - Unless H loss by Vomiting or gastric aspiration
- Pulmonary Oedema
  - Salt and Water Retention
- Acute Or Chronic?
  - Acute
    - Rapid Rise in Serum Urea and Creatinine
  - Chronic
    - Normochromic Normocytic Anaemia
      - Haemolysis
      - Low EPO
      - Haemorrhage
    - Renal Osteodystrophy
  - Ultrasound
    - Small Kidneys
- Pre-renal/Renal/Post Renal Uraemia ?
  - Catheter or Flushing existing
    - Bladder obstruction
  - Renal UltraSonography
    - Dilation of Tract
      - Obstruction
  - Pre-renal vs Renal is difficult
    - Renal
      - Specific Gravity Urine
        <1.01
      - Urine Osmolaity
        <350
      - Urine Na
        >40
- Volume Status
  - Low
    - Corrective Methods
      - No Diuresis
        AKI
- U&Es
  - Hyperkalaemia
    - trauma to muscles
  - Hyponatraemia
    - Fluid Overload due to Oliguria
  - Hypocalcaemia
    - Reduced Production of Vit D
  - Hyperphosphateaemia
    - Phosphate retention
  - UREA
    - Increases in 48-72 hours
      - For Early Rx
        Plasma Biomarkers
        Kidney Injury Molecule 1
        Lipocalin
- FBC
- LFTs
  - ALP Increased
- Blood Cultures
Management
- Aim
  - Keep Patient Alive until spontaneous recovery of renal function
- General Measures
  - Good nursing and Physio
  - Regular Oral Hygiene
  - Chest Physio
  - Fluid Balance Chart
- Emergency Measures
  - Hyperkalaemia
    - Risk of Cardiac dysrhythmias
      - VF
    - ECG and I.V. access
      - Protect Myocardium
        10mL of 10% Calcium Gluconate i.v. over 15 minutes
      - Drive K into cells
        Insulin 10 Units + 50mL of 50% Glucose i.v. over 10-15 mins
        Correct acidosis
        Infuse NaHCO3
        May be inappropriate
        Na and WATER Overload in AKI
        Pt Hypocalcaemia
        May trigger tetany
      - Once Settled
        Deplete body K over 24 hours
        Polystrene sulphonate resins
        15g PO TDS w/Laxatives
        30g PR then enema 9 Hrs later
        Dialysis can be used instead
  - Pulmonary oedema
    - IV Furosemide
    - Dialysis/ Haemofiltration
  - Infection
    - Rx but avoid nephrotoxic drugs
  - Fluid and Electrolyte balance
    - Assess BD
    - Fluid Balance
      - If Abnormal Losses
        Replace Fluids and Electrolytes
    - Sodium and K intake minimized
  - Diet
    - Sodium and K intake are minimized
    - Protein intake increased
      - Hypercatabolic Pts
      - Blood purification
  - Dialysis and Haemofiltration
    - Indications
      - Symptoms of Uraemia
      - Complications of Uraemia
        Pericarditis
      - severe biochemical derangement in absence of symptoms
      - Hyperkalaemia not controlled by conventional methods
      - Pulmonary Oedema
      - Severe acidosis
      - REMOVE DRUGS CAUSING AKI
    - Intermittent Haemodialysis with ultrafilration
    - intermittent haemofiltration
    - Continuous arteriovenous or venovenous...
      - Haemofiltration
      - Haemodiafiltration
      - Peritoneal dialysis
        Drawbacks
        Low efficiency in fluid and solute removal compred to CRRT or intermittent HD
        AKI complicating intra-abdominal pathology is unsuitable for PD
        Increasing intra-abdominal pressure can compromise lung function
        High Glucose - Hyperglycaemia and other metabolic derrangements.
    - Continual RENAL REPLACEMENT
      - CAVH/ CVVH
        Continuous removal of filtrate from patient
        Infusion of replacement solution
      - CAVHDF / CVVHDF
        Ultrafiltration WITH Dialysis
- AKI in ICU
  - Who?
    - Multiple Organ Failure
      - ARDS can occur
        Remove as much fluids as possible
        Blood Transfusions
        EPO
    - Sepsis
    - Cardiovascular Instability
  - Fluids
    - Replacement
      - 0.9% Saline
      - 4% Albumin
    - Overload
      - Diuretics
  - Nutrition
    - Enteral Feeding preferred
    - Parenteral if severally malnourished or if unable to eat for >14 days
  - Dialysis
    - Early Initiation of RRT
    - Continuous better than intermittent
      - Much less disturbance of cardiovascular stability
      - Generates more 'space' for fluids
      - More porous membranes
        Remove harmful cytokines
- Recovery Phase
  - After 1-3 weeks
    - Increased Urine Output
    - Serum Biochemistry better
  - Discontinue Dialysis or Haemofiltraion
  - Careful watch U&Es, water and serum biochemisry
  - Fluid supplements inc Na and K may be required
Complications
- Acute Cortical Necrosis
- Contrast Nephropathy
  - Transient and fully recoverable
  - Increased Risk
    - Cardiovascular event
    - ESKD
  - Amplified by:
    - Hypovolaemia
    - CKD
      - Metformin
  - Periprocedural Haemofiltration
- Acute Phosphate Nephropathy
  - Sodium Phosphate PO
    - Bowel Prep
  - Risks
    - CKD
    - Dehydration
    - Older Age
    - HTN

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Description: Renal Mind Map on Acute Kidney Injury, created by Beoluf Jangan on 10/01/2018.
Created by: Beoluf Jangan
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Acute Kidney Injury

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