Flashcards
Renal Critical Care
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- 1Kidney homeostasismaintenance of stable extracellular environment required for cell function
regulation of water, electrolyte, acid-base balance
excretion of products
drug excretion and metabolism - 2The kidneyrate of glomerular filtration - 135-180l per day
high metabolic requirements - 3Auto-regulationcontrol of renal blood flow and GFR
decrease in renal blood flow = vasodilation, vasocontriction - 4Auto regulation thresholdrange is normally 90-200mmHG
- 5Functions of kidneysExcretory - excretion of metabolic waste products
regulatory - electrolyte balance
Metabolic - production of EPO, renin - 6Renal failureacute - usually resolves in 6 weeks
chronic - may last years
end stage - less than 5% function, little UO - 7Classification of renal failureAKI - sudden onset, reversible
End stage - less than 15% function - 8AKIsudden 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 - 9AKI causespre-renal - hypovolemia, shock, septicaemia
intrinsic renal - vascular, intratubula pigments
post renal - obstruction of urinary tract - 10AKI defined in lab resultselevated serum creatinine above 26.5 within 48 hours
1.5 times baseline within 7 days
urine volume 0.5ml for 6 hours per hour - 11Definition of CKDprogressive disease of kidney
causes irreversible damage to nephrons - 12Clinical presentation of CKD- up yo 90% kidney function lost
- hypertension, pruitus, nocturia, nausea/vomiting, fatique - 13Medications that affect CKDtriple whammy - ace inhibitor, diuretic, NSAID
- 14Diagnostic tests- blood tests - urea, creatinine, electrolytes, FBC
radiology - US, Renal biopsy, CT scan, MRI - 15Ureaserum 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 - 16Creatinineby-product of phosphate breakdown in skeletal muscle
- proportional to muscle mass
- 0.8 - 1.2 mmol nomrmal value - 17Diagnosing renal imparimentUO
Proteinuria
serum urea
creatinine - 18Urine outputabsence of endocrine abnormalities
decrease GFR
pre-renal AKI - decrease UO - 19Indications for dialysisfluid overload - PO
uraemia symptoms - nausea, vomiting, drosiness, confusion
Hyperkalemia
acidosis arterial - 20HaemodialysisAV fistula: subcutaneous anastamosis between artery and vein
Graft - artifical connection between an artery and vein made of PTFE
principles: diffusion, osmosis, convection - 21Peritoneal dialysis- peritoneum used as membrane
- 22Impaired kidney functionalbuminuria, loss of tubular proteins, inability to effectivly excrete water and solutes
- 23causes of AKI in crit caresepsis
nephro-toxic agents
following cardiac surgery
trauma - 24Acute tubular necrosisIntrinsic renal injury
damgaes the tubules, loop of henle at rick
causes: hypoperfusion, blood transfusions, sepsis, metabolic disturbances - 25Actionsminimise risk factors
maintain MAP
oxygenate
UO, K, acid-base balance, resp function - 26Volume expansionin the presence of hypovolaemia
Hydration van be helpful - 27Blood pressuremaintain MAP above 65
renal perfusion requirements - 28InotropesNoradrenaline: increases MAP without causing renal vasoconstriction
Vasopressin - beneficial in severe sepsis - 29Diuretics - Frusemideincrease blood flow, improve GFR, decreasing tubular reabsorption
delay requirement for RRT - 30RRT and indicationsrenal replacement therapy
indications: AKI, severe sepsis, diuretic PO, drug removal - 31Aim for rrteskd - fluid removal and waste
AKI in ICU - filtration, remove wastes, dialysis tolerance - 32Principlesutilise semi-permeable membrane through which water and solutes are removed
either biological (peritoneum) or artificial (extracorporeal) - 33Membrance/filtermembrane capacity - SA exposed to blood
number of pores, absorption capacity
high plasa water clearance at low blood rates - 34Ultrafiltrationwater is transported through the membrance
pressure gradient across the membrane is required
gradient must be greater than the oncotic pressure maintaining intra-vascular volume - 35Diffusionmovement 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 - 36Convectionmovement 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 - 37Convection contsolute 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 - 38adsorptionadhesion 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 - 39Peritoneal dialysisNot routinely used
Vascular access is not possible
CVS instability
probelms:
poor solute clearance, high risk of peritonitis, metabolic disturbances, protein loss - 40Intermittent haemodialysismainstay therapy for treatment of renal failure
- remains the predominant form of dialysis - 41IHD continued3-6 times per week
duration 4-5 hours
volumes removal done by ultrafiltration
solute removal by diffusion
solute clearance is dependent on the blood flow - 42Advantages of IHD in AKIinexpensive, short duration, rapidly remove solutes, decreased need to anti-coagulants
- 43Disadvantages of IHDrequires tolerance for variant solute and fluid levels, diet and fluid restrictions
less accurate assessment of fluid removal - 44Dialysis disequilibriumcausing symptoms of raised ICP
- headache, nausea, vomiting, seizures , coma - 45Hypotensionmain risk for unstable patients in ICU
reduced efficiency of treatment
exarcerbate renal damages - 46Sustained low efficiency dailySLEDD
dialysis
increasingly used
duration 6-12 hours
blood flows 150-300/min
volue removal done by ultrafiltration
solute removal done by diffusion - 47Advanatages of SLEDDcheaper than CRRT
less hypotension impact
reduced anti-coagulant requirements - 48Disadvantages of SLEDDincreased machine maintenence
higher haemodynamic impact
risk of raised ICP
less accurate assessment of fluid removal - 49CRRT advantageseffective with controlling fluid balance and solute removal
nutritional support and fluids
better haemodynamic tolerance
prevention of cerebral osmolarity swings - 50CRRT disadvantagesexpensive
time intensive
patient immobility
solute and water clearance is dependent on sustained filter time - 51Dialysis Dose/intensityaim for dose 25ml/kg/hr
- 52Anticoagulationextracorporeal passgae of blood through CRRT will activate the clotting pathway
anticoagulation is administred to reduce clots forming in the filter - 53No anticoagulationcan be maximised by
maintaining blood flow
pre-filter replacement
reliable vascular access
flushing of lines - 54Filter lifesolute clearance in CRRT can only be acheived if filters are functioning
frequent filter changes - 55Complicationsbleeding
thombpocytopenia, haemolysis
hypovolaemia
infection, air emboli, hypothermia, immoboloty - 56PharmacologyPatients on CRRT clear most renally excreted drugs effectively
ensure adequate plasma conc
durg dosage may have to increased when on CRRT - 57Nursing CareFluid 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 - 58Managementaim to establish normal haemodynamices in an effort to restore renal perfusion
fluid replacement, stimulation of urine output, management of electrolytes - 59Care managementdiet - commence to avoid further breakdown
care of access points, skin intrgrity , pt educatioin
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- Criado por Elizabeth Then · 29 ago 2018
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