2. Kidney plays vital role in:
● regulating the volume & composition of body fluids and acid base balance.
● eliminating toxins
● producing hormones like renin, erythropoietin, active vitamin D.
- Each kidney 1 million functional units ( nephrons).
Each nephron consists of –
▪ Renal corpuscle ( Glomerulus, Bowman’s capsule, mesangial cells)
▪ Proximal convoluted tubule
▪ Loop of henle (descending and ascending)
▪ Distal tubule
▪ Collecting tubule
▪ Juxtaglomerular Apparatus.
Introduction
3.
4. Combined blood flow through both kidneys (20-25% of total cardiac output)
80% of RBF goes to cortical nephrons. 10-15% goes to juxtamedullary nephrons.
CLEARENCE - volume of blood completely cleared of a substance per unit of time.
RENAL PLASMA FLOW = clearence of PAH
{ [ PAH]u / [PAH]p} x urine flow
RENAL BLOOD FLOW = RPF / (1- haematocrit)
Normal RPF = 660 ml/min Normal RPF = 1200 ml/min
Renal circulation
5. Glomerular Filtration Rate
Volume of fluid filtered from the glomerular capillaries into
bowman’s capsule per unit time
Normal values - 120 +/- 25 ml/min (male)
95 +/- 20 ml/min (female)
Calculated using inulin or creatinine clearence
Filtration Fraction = GFR/RPF = ( 20%)
Autoregulation of renal blood flow occurs between MAP of 80 and
180 mm Hg
6. Acute Renal Failure
“Acute renal failure (ARF) or Acute kidney injury
(AKI) is characterised by deterioration of renal
functions over a period of hours to few days,
resulting in failure of the kidneys to excrete
nitrogenous waste product and to maintain fluid,
electrolytes and acid-base homeostasis”.
7. Staging of Acute Kidney Injury (AKIN)
Stage Serum Creatinine criteria Urine output criteria
1 Increase in s.creatinine of ≥0.3 mg/dl (≥26.4 μmol/l) or
increase to ≥150% to 200% (1.5- to 2fold) from
baseline
Less than 0.5 ml/kg/hr
for more than 6 hours
2 Increase in s.creatinine to more than 200% to 300% (>
2 to 3 fold) from baseline
Less than 0.5 ml/kg/hr
for more than 12 hours
3 Increase in s.creatinine to more than 300% (> 3 fold)
from baseline (or s.creatinine of ≥4 mg/dl [≥ 354
μmol/l] with an acute increase of at least 0.5 mg/dl [44
μmol/l])
Less than 0.3 ml/kg/hr
for 24 hours or anuria
for 12 hours
11. Chronic renal failure/CKD is characterized by a
progressive and irreversible decline in renal function
over the course of at least 3-6 months
CHRONIC RENAL FAILURE
12. Pre operative evaluation
Most patient with ARF requiring surgery are critically ill
Optimal peri operative management dependent on
preoperative dialysis
Preoperative dialysis on the day or previous day of
surgery
Physical and lab examination to assess cardiac and
pulmonary function
Physical signs of fluid overload ,hypovolemia checked
13. Pre operative evaluation
Pre ,current and post dialysis weight
pre operative red blood cell transfusion
Drug therapy should be carefully reviewed
19. Opioids
Morphine Conj. to M-3-G, M-6-G
, active metabolite, resp
depresion
Active metabolite has renal
elimination, 40% conj
occurs in kidney
Dose adjustment
required
Meperidine
(Pethidine)
Normeperidine, CNS
toxicity
Active metabolite has renal
elimination
Dose adjustment
required
Fentanyl ↓ Plasma protein
binding,↑ free drug
Clearance not altered safe
Sufentanil ↓ Plasma protein
binding,↑ free drug
Clearance not altered safe
Alfentanil ↓ Initial vol of
distribution,↑ free drug
Clearance not altered safe
Remifentanil No change Clearance not altered safe
20. Inhalation Agents
Halothane Inorganic fluoride levels are less No Neprotoxicity
Isoflurane Inorganic fluoride levels are less No Neprotoxicity
Desflurane Inorganic fluoride levels are very less, highly
stable & resists degradation by soda-lime & liver
No Neprotoxicity
Sevoflurane Inorganic fluoride levels are less but not stable ,
degraded by soda-lime to compound A &
undergoes liver metabolism
Compound A is
neprotoxic
Enflurane Biotranformed to inorganic fluoride levels after
prolonged use (> 4hrs)
Nephrotoxic,after
prolonged use
Methoxyflurane Biotranformed to high inorganic fluoride levels Highly
nephrotoxic
21. Intravenous Agents
Thiopentone CNS effect reversed by redistribution &
hepatic metabolism, also 80% protein
bound, ↓albumin in uremia, ↑ free drug,
more free un-ionised drug in acidosis
Metabolism unchanged ,
↓ excretion,
Used in ↓ dose
Propofol Metabolised by liver No adverse effect
Etomidate Metabolised by liver, partial renal
excretion
No adverse effect
Benzodiazepines Metabolised in liver & excreted by
kidney, longer acting BZD accumulate, ↑
duration of action
↑ Interval or ↓ dose
22. Local anaesthetics
Dose reduction needed
Respiratory or metabolic acidosis increases the risks for
CNS toxicity from local anesthetics
Elevated PaCO2 enhances cerebral blood flow and thus the
anesthetic is delivered more rapidly to the brain.
In addition, diffusion of carbon dioxide into neuronal cells
decreases intracellular pH, which facilitates conversion of
the base form of the drugs to the cationic form.
23. Monitoring
• All routine monitoring – ECG, NIBP, SpO₂, EtCO₂, NM
monitoring
• Monitoring urinary output and intravascular volume
(desirable urinary output: 0.5 ml/kg/hr)
• Intra-arterial, central venous, pulmonary artery monitoring
are often indicated
• Intra-arterial blood pressure monitoring in poorly
controlled hypertensive patients
24. Pre-Medication
Reduced doses of an opioid or BZD,
H2 blocker - Aspiration prophylaxis,
Metoclopramide -10 mg for accelerating gastric emptying,
prevent vomiting, ↓risk of aspiration,
Antihypertensive agents should be continued until the time
of surgery.
25. Induction
Patients are at increased risk of aspiration: rapid-
sequence induction with cricoid pressure.
Drugs Normal Dosages Altered Dosages
Thiopental 3-5 mg/kg 2-3 mg/kg
Propofol 1-2 mg/kg 1-2 mg/kg
Etomidate 0.2-0.4 mg/kg 0.2-0.4 mg/kg
Succinylcholine 1-2 mg/kg 0.5-1.5 mg/kg
Atracurium 0.6 mg/kg 0.6 mg/kg
Cisatracurium 0.15 mg/kg 0.15 mg/kg
26. Maintenance
Ideal maintenance - control hypertension with minimal
effects on cardiac output,
Controlled ventilation with cuffed endo-tracheal tube should
be considered for patients with renal failure,
Fluid therapy: D5W, isotonic crystalloids (lactated Ringer’s?,
NS), colloids, pRBC,
Anaesthesia can be maintained with inhalation agents or
propofol with muscle relaxants with NM monitoring.
27. Reversal
• Neuro-muscular blockage is reversed with Neostigmine or
pyridostgmine in combination with anticholenergic.
• Neostigmine and pyridostgmine has 50% & 70% renal elimination
respectively.
• Glycopyrolate has 80% renal excretion so should be used
cautiously.
• Atropine undergoes 25% renal elimination and rest hepatic
metabolism to form metabolite noratropine which has renal
excretion.
• Extubation should be done after complete reversal of NM blockage.
28. Post Operative
• Monitoring of fluid overload or hypovolemia titrated fluids,
• Residual neuromuscular blockade,
• Monitoring of urea and electrolytes,
• ECG monitoring for detecting cardiac dysrhythmias.
• Continue oxygen supplementation in post operative period,
• Analgesia with regional,
• Carefully titrated opioids, ↑CNS depression, respiratory depression
– naloxone.
30. summary
Patients presenting for surgery with renal insufficiency or
failure present a significant challenge for the
anesthesiologis
It is imperative that the anesthesiologist not only
understands the management of these complex patients
but also intervenes to prevent further renal injury during
the perioperative period.
Judicious fluid management,the maintenance of
normovolemia, and avoidance of hypotension are priorities
for the successful prevention of further renal injury
