Renal Critical Care

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Flashcards on Renal Critical Care, created by Elizabeth Then on 29/08/2018.
Elizabeth Then
Flashcards by Elizabeth Then, updated more than 1 year ago
Elizabeth Then
Created by Elizabeth Then over 5 years ago
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Question Answer
Kidney homeostasis maintenance of stable extracellular environment required for cell function regulation of water, electrolyte, acid-base balance excretion of products drug excretion and metabolism
The kidney rate of glomerular filtration - 135-180l per day high metabolic requirements
Auto-regulation control of renal blood flow and GFR decrease in renal blood flow = vasodilation, vasocontriction
Auto regulation threshold range is normally 90-200mmHG
Functions of kidneys Excretory - excretion of metabolic waste products regulatory - electrolyte balance Metabolic - production of EPO, renin
Renal failure acute - usually resolves in 6 weeks chronic - may last years end stage - less than 5% function, little UO
Classification of renal failure AKI - sudden onset, reversible End stage - less than 15% function
AKI sudden decreased in renal function pre renal - relates to ineffective perfusion of kidneys, occurs outside of kidney renal - occurs in kidneys, can be secondary to pre-renal, structural damage to bv and tubules Post renal - disordered urinary drainage
AKI causes pre-renal - hypovolemia, shock, septicaemia intrinsic renal - vascular, intratubula pigments post renal - obstruction of urinary tract
AKI defined in lab results elevated serum creatinine above 26.5 within 48 hours 1.5 times baseline within 7 days urine volume 0.5ml for 6 hours per hour
Definition of CKD progressive disease of kidney causes irreversible damage to nephrons
Clinical presentation of CKD - up yo 90% kidney function lost - hypertension, pruitus, nocturia, nausea/vomiting, fatique
Medications that affect CKD triple whammy - ace inhibitor, diuretic, NSAID
Diagnostic tests - blood tests - urea, creatinine, electrolytes, FBC radiology - US, Renal biopsy, CT scan, MRI
Urea serum urea - by product of protein metabolism, not an accurate assessment of renal function - 2.7-8mol normal value - measurement effected by dietary protein intake, GI bleeding
Creatinine by-product of phosphate breakdown in skeletal muscle - proportional to muscle mass - 0.8 - 1.2 mmol nomrmal value
Diagnosing renal impariment UO Proteinuria serum urea creatinine
Urine output absence of endocrine abnormalities decrease GFR pre-renal AKI - decrease UO
Indications for dialysis fluid overload - PO uraemia symptoms - nausea, vomiting, drosiness, confusion Hyperkalemia acidosis arterial
Haemodialysis AV fistula: subcutaneous anastamosis between artery and vein Graft - artifical connection between an artery and vein made of PTFE principles: diffusion, osmosis, convection
Peritoneal dialysis - peritoneum used as membrane
Impaired kidney function albuminuria, loss of tubular proteins, inability to effectivly excrete water and solutes
causes of AKI in crit care sepsis nephro-toxic agents following cardiac surgery trauma
Acute tubular necrosis Intrinsic renal injury damgaes the tubules, loop of henle at rick causes: hypoperfusion, blood transfusions, sepsis, metabolic disturbances
Actions minimise risk factors maintain MAP oxygenate UO, K, acid-base balance, resp function
Volume expansion in the presence of hypovolaemia Hydration van be helpful
Blood pressure maintain MAP above 65 renal perfusion requirements
Inotropes Noradrenaline: increases MAP without causing renal vasoconstriction Vasopressin - beneficial in severe sepsis
Diuretics - Frusemide increase blood flow, improve GFR, decreasing tubular reabsorption delay requirement for RRT
RRT and indications renal replacement therapy indications: AKI, severe sepsis, diuretic PO, drug removal
Aim for rrt eskd - fluid removal and waste AKI in ICU - filtration, remove wastes, dialysis tolerance
Principles utilise semi-permeable membrane through which water and solutes are removed either biological (peritoneum) or artificial (extracorporeal)
Membrance/filter membrane capacity - SA exposed to blood number of pores, absorption capacity high plasa water clearance at low blood rates
Ultrafiltration water is transported through the membrance pressure gradient across the membrane is required gradient must be greater than the oncotic pressure maintaining intra-vascular volume
Diffusion movement of solutes from area high to low concentration until equilibrium is established concentration gradient is the stimulus for solute movement dependent on size of molecule, permeability of membrane, solute concentration gradient Solute removal by diffusion controlled by: blood flow rate, dialysis flow rate, membrane permeability and SA dialysis fluids run through filter to create the solute concentration gradient and are not directly infused into the blood stream
Convection movement of solutes under pressure through a membrane with water creates a pressure gradient which moves water through the membrane Filter pore size prevents large molecules from going through increasing membrane gradient will move more water and solutes through the membrane
Convection cont solute removal by convection is controlled by ultrafiltration rate and membrane sieving capacity results large shifts of water across the membrance which must be replaced to prevent hypovolaemia replacement fluid which is added to pts blood to maintain volume
adsorption adhesion of solutes to the membrane filter capacity is dependent on nature of membrance primary mechanism of the removal of inflammatory mediators when septic patients are on renal replacement
Peritoneal dialysis Not routinely used Vascular access is not possible CVS instability probelms: poor solute clearance, high risk of peritonitis, metabolic disturbances, protein loss
Intermittent haemodialysis mainstay therapy for treatment of renal failure - remains the predominant form of dialysis
IHD continued 3-6 times per week duration 4-5 hours volumes removal done by ultrafiltration solute removal by diffusion solute clearance is dependent on the blood flow
Advantages of IHD in AKI inexpensive, short duration, rapidly remove solutes, decreased need to anti-coagulants
Disadvantages of IHD requires tolerance for variant solute and fluid levels, diet and fluid restrictions less accurate assessment of fluid removal
Dialysis disequilibrium causing symptoms of raised ICP - headache, nausea, vomiting, seizures , coma
Hypotension main risk for unstable patients in ICU reduced efficiency of treatment exarcerbate renal damages
Sustained low efficiency daily SLEDD dialysis increasingly used duration 6-12 hours blood flows 150-300/min volue removal done by ultrafiltration solute removal done by diffusion
Advanatages of SLEDD cheaper than CRRT less hypotension impact reduced anti-coagulant requirements
Disadvantages of SLEDD increased machine maintenence higher haemodynamic impact risk of raised ICP less accurate assessment of fluid removal
CRRT advantages effective with controlling fluid balance and solute removal nutritional support and fluids better haemodynamic tolerance prevention of cerebral osmolarity swings
CRRT disadvantages expensive time intensive patient immobility solute and water clearance is dependent on sustained filter time
Dialysis Dose/intensity aim for dose 25ml/kg/hr
Anticoagulation extracorporeal passgae of blood through CRRT will activate the clotting pathway anticoagulation is administred to reduce clots forming in the filter
No anticoagulation can be maximised by maintaining blood flow pre-filter replacement reliable vascular access flushing of lines
Filter life solute clearance in CRRT can only be acheived if filters are functioning frequent filter changes
Complications bleeding thombpocytopenia, haemolysis hypovolaemia infection, air emboli, hypothermia, immoboloty
Pharmacology Patients on CRRT clear most renally excreted drugs effectively ensure adequate plasma conc durg dosage may have to increased when on CRRT
Nursing Care Fluid balance, weight, urine tests, Uraemia, nausea, vomiting, infection, nutrition, low K, no added salt, reduced protein Care of skin, medication, antihypertensive therapy, EPO injections, lifestyle management
Management aim to establish normal haemodynamices in an effort to restore renal perfusion fluid replacement, stimulation of urine output, management of electrolytes
Care management diet - commence to avoid further breakdown care of access points, skin intrgrity , pt educatioin
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