Chronic Renal Failure (CRF)

Chronic Renal Failure

Definition

Irreversible deterioration in renal function

Classification – 5stages

Stage	Description	GRF (ml/min/ 1.73m3)	Action
1	Kidney damage with N/↑GFR	>90	Investigate
2	Kidney damage w slightly low GFR	60-89	Renoprotection – BP, diet
3	Moderately low GFR	30-59
4	Severe low GFR	15-29	Consider RRT
5	Kidney failure	<15 or dialysis

Aetiology

Disease	%
DM	20-40
HTN	5-25
Glomerular disease -IgA nephropathy common	10-20
Interstitial disease	5-15
Systemic inflammatory e.g. SLE, vasculitis	5
RAS	5
Congenital/inherited -PKD, Alports disease	5
Unknown	5-20

History

Symptoms

Fluid overload – ankle swelling, SOB,urine output

Uraemic symtoms

·         Anorexia, vomiting, , metalic taste

·         Fatigue, weakness,hiccup

·         Pruritus,bruise

Signs

Pallor,  yellow skin pigmentation

V/S: ↑BP, ↑RR, Kussmaul’s respiration, pulsus paradoxus

Brown nail

Purpura, bruising, excoriation, AV fistulae

Conjuctival pallor

JVP ↑

Displaced apex beat, pericardial friction rub

Bibasal Crepitation

Tenckhoff catheter

Leg swelling

I(x)

Blood HB ↓ (normochromic, normocytic) ESR U&E (↑ urea, ↑creatinine) ↓Ca2+, ↑PO43-, ↑ ALP (renal osteodystrophy) ↑PTH

Urine MC&S, dipstick, urine PCI or 24h urine protein

Imaging Renal US – TRO obstruction, measure size Small <9cm Large -DM, PKD, amyloidosis, myeloma, systemic sclerosis, asymmetrical renal vascular DTPA scan CXR – cardiomegaly, pleural/pericardial effusion, pulmonary oedema Bone  X-ray – TRO renal osteodystrophy Renal biopsy

Complications

Anaemia	Def of EPO Diminished erythropoisis dt toxic effect of uraemia on BM ↓red cell survivors ↓dietary intake and absorption of iron
Bleeding	Capillary fragility, poor platelet function
Fluid and electrolyte balance	↓concentrating ability
Acidosis
Infection	Cellular and humoral immunity are impaired
Renal osteodystrophy	Impaired renal function (1) ↓PO43-  secretion à ↑plasma [PO43- ] (2)↓1,25 (OH)2Vit D à↓Ca2+ absorption à↓plasma [Ca2+] Both (1),(2) àstimulate PTH gland (hyperplasia) à↑PTHà↑osteoclastic activityà↑bone resorption
Generalised myopathy	Dt combination of poor nutrition, hyperparathyroidism, Vid D def, disorder of  electrolyte metabolism
Neuropathy	Dt demyelination of medullated fibres, longer fibres – earlier stage Sensory -paraesthesia -tx:amytriptaline, gabapentin Motor -foot drop Autonomic -delayed gastric emptying -diarrhoea -postural hypotension

Treatments

Refer to nephrologist

Treat reversible causes

I.            HTN       II.            ↓ renal perfusion     III.            RAS     IV.            Hypotension dt drug treatment

V.            Sodium, water depletion     VI.            Poor cardiac output   VII.            UT obstruction VIII.            UTI     IX.            Nephrotoxic med

HTN – small Bp dropàimprove significant renal function	-Tx: ACE-i, A2A -target: 130/80, (125/75 if >1g proteinuric/d)
Oedema	– frusemide 250mg-2g/24h ± metolazone 5-10mg/24h PO mane -fluid restriction
Anaemia	EPO
Renal osteodystrophy	Restrict dietary phosphate e.g. egg, cheese, milk Vit D analogue – Alphacalcidol=1α-hydroxycholecalciferol Ca2+ supplement Phosphate binder in gut (e.g. Calchichew)
Restless legs	Clonazepam -0.5-2mg/d

Renal replacement therapy

Indications (7)

1.       Fluid overload

2.       ↓urine output

3.       Uraemic symptoms

4.       Uraemic encephalopathy

5.       ↑urea

6.       Hyperkalaemia

7.       Metabolic acidosis

Methods  of RRT

1.       Haemodialysis (HD)

Blood flows on one side of semi-permeable membrane, while dialysate flows in the opposite direction

Solute transfers occur by diffusion.

Ultrafiltration is the removal of excess fluid by creating negative transmembrane perssure.

Problems

                                i.            Disequilibrium syndrome

                               ii.            hypotension, arrhythmias

                             iii.            Bleeding, haemolysis, air embolism

                             iv.            Time consuming

                              v.            Access

Fistula - thrombosis, stenosis, aneurysm, steal syndrome, ischaemic

Temporary line -  infection, blockage

2.       Haemofiltration

Blood is filtered continuously acoss highly permeable synthetic membrane.

Removal of waste product by a process called convection.

Ultrafiltrate is substituted with an equal volume of replacement fluid.

Advantage – less haemodynamical instability

Disadvantages – > expensive, longer than HD

3.       Peritoneal dialysis

                                I.            CAPD (continuous ambulatory

peritoneal dialysis)

2L bags aer changed 3-5 times/day, total dialysate of 10L

                              II.            Automated peritoneal dialysis

Use cyler machine to enhance solute and fluid removal

Techniques (4)

                                                 i.            CCPD (continuous cylic PD)

                                               ii.            IPD (Intermitted PD)

                                              iii.            NIPD (Night intermittent PD)

                                             iv.            TIPD (tidal intermittent PD)

Problems with PD

exit site leak  poor inflow/ outflow  pelvic/ abdo pain  faeculent/ bloody effluent

unilat pleural effusion poor metabolic control hyperglycaemia in DM patients peritonitis

Haemodialysis vs  peritoneal dialysis

Haemodialysis	PD
Efficient	Less efficient
4hrs, 3 times / week	4 exchanges/day
2-3 days bet treatment	Few hours bet treatment
Visit to hosp	Performed at home
Requires adequate venous circulation	Require intact peritoneal membrane
Compliance with diet and fluid restriction	Diet and fluid less restricted
Symptoms and haemodynamic instability	Asymptomatic, less haemodynamic instability
Infection related to vascular access	Peritonitis and catheter-related infection

Complication of dialysis

1.       Cardiovascular diseases

e.g IHD, CF, stroke > common

2.       HTN

3.       Anaemia – Rx: EPO ±haematinics

4.       Bleeding tendency

-dt platelet dysfunction

-Rx – desmopressin, transfusion

5.       Renal bone disease

-Rx: diet, alfacalcidol, Ca²⁺supplement, phospate binders

6.       Infection –dt non-sterility procedure

7.       Β₂-microglobulin amyloidosis

-dt accumulation of amyloid

-compl: Carpal tunnel syndrome, arthralgia, #

8.       Acquired renal cyst

-present with haematuria or malignant transformation

9.       Malignancy

e.g. urothelial tumour in analgesic nephropath

Discussion

Haemodialysis fluid (dialysate)

1.       K3 (low calcium)

2.       K5 (standard calcium)

3.       K6 (high calcium)

3 types of fistula (AVF)

1.       Brachiocephalic fistula (BCF)

2.       Brachiobasillic fistula (BBF)

3.       Radio cephalic fistula (RCF)

Factors involved in determining site of fistula

1.       Non dominant hand

Risk of steal syndrome

2.       Distil first – radio àbrachial

Types of Temporary line

1.       Femoral catheter – last  <1w

2.       IJC – last up to 2 months

Only for good cardiac function

Buy time for AVF to mature

Hand grip exercise 3h/d àspeed up maturity of fistula

Screening before starting HD

1.       Hep B

2.       Hep C

3.       HIV

Aim: to avoid contamination of the machine, thus transmission of infection

Eat High calcium food

Avoid high phosphate food

Hyperkalaemia findings on ECG

1.       Absent P wave

2.       Prolong PR interval

3.       Widening of QRS complex

4.       Tall T wave

Hyperkalaemia in CRF

Rule out causes for hyper K

1.       ACE-i, suxamethonium

2.       K-sparing diuretics

3.       Massive blood transfusion

4.       Delay in analysis – K leak out of RBC

5.       Rhabdomyolysis, burn

6.       Metabolic acidosis

7.       Addison’s disease

8.       Excess K therapy

Treatment of hyperkalaemia

1.       Calcium

10ml of 10% calcium gluconate IV over 2min

2.       IV glucose + insulin

50ml Dextrose 50% + 10U Actrapid insulin IV over 30min

MOA: insulin stimulates intracellular uptake of K⁺, lowering serum K⁺ by 1-2mmol/l over 60min

3.       Salbutamol 5mg nebulizer

4.       Haemodialysis