elimination enhancement powerpoint presentation

It mainly contains elimination enhancement methods used in elimination of poison

1. ELIMINATION ENHANCEMENT

2. EPIDEMIOLOGY Alkalinisation of urine reportedly used 9430 times MDAC- 3114 times Hemodialysis – 2106 times Hemoperfusion- 16 time s Lithium and ethylene glycol were most common xenobiotics for which hemodialysis was used INDICATIONS Patient who fail to respond to supportive care Patient in whom normal route of elimination of xenobiotic is impaired Patients in whom amount of xenobiotic or its high concentration in serum indicates morbidity or mortality Patients with concurrent disease /in any age group Patients with electrolyte disorders to be corrected

3. Characteristics for extra corporeal therapy Vd (l/kg) × patient weight = dose (mg) / concentration Lipid soluble xenobiotics are highly protein bound have large volumes of distribution can exceed TBW Pharmacokinetics influence ability to enhance elimination

4. FORCED DIURESIS It is done by 0.9% Nacl and ringer lactate solution Mostly used for lithium which has GFR is important determinant of excretion Loss of extracellular volume leads to reduction of GFR partly as a result of decreased cardiac output After the ECF is restored continuous infusion of 0.9% Nacl The risk of this therapy is ECF volume overload Administration of diuretics such as furosemide and saline decrease the risk of ECF overload Acidification of urine enhance elimination of weak acids such as salicylates, phenobarbital , diflunisal and methotrexate Alkalinisation of sodium bicarbonate to increase urine pH of 7-8 Forced diuresis is a medical procedure that involves inducing an increase in urine formation in order to hasten the elimination of drugs from the body and detoxify patients who have overdosed on certain drugs.

5. The procedure should be undertaken if the conditions are satisfied Hepatic degradation produces active metabolites The procedure should be taken when conditions are met A portion of drug is excreted unchanged The drug is distributed mainly in extracellular fluid The drug is minimally protein bound PRINCIPLE Most drugs are weak acids exist as undissociated molecules at physiologic PH . The extension of ionisation is the function Of ionisation constant of the drug . Ionisations usually expressed in the form of negative logarithm Thus the rate of diffusion from the renal lumen back to the circulation is decreased when drug is maximally ionised This is mostly used in case of phenobarbitone , lithium and salicylates Administer 500ml of fluid IV 500ml of 5% dextrose 500ml of 1.2 or 1.4 % NaHCO3

6. PERITONEAL DIALYSIS A soft plastic tube (catheter) is placed in your belly by surgery. A sterile cleansing fluid is put into your belly through this catheter. After the filtering process is finished, the fluid leaves your body through the catheter. There are two kinds of peritoneal dialysis: 1. Continuous Ambulatory Peritoneal Dialysis (CAPD) 2. Automated Peritoneal Dialysis (APD) CAPD is "continuous," machine-free and done while you go about your normal activities such as work or school. You do the treatment by placing about two quarts of cleansing fluid into your belly and later draining it. This is done by hooking up a plastic bag of cleansing fluid to the tube in your belly. Raising the plastic bag to shoulder level causes gravity to pull the fluid into your belly. When empty, the plastic bag is removed and thrown away. APD differs from CAPD in that a machine (cycler) delivers and then drains the cleansing fluid for you. The treatment usually is done at night while you sleep.

7. It enhances elimination of a water soluble low molecular weight with low vd such as Alcohols Lithium Salicylate Theophylline The highest clearances achieved for molecules with molecular weight of 500 daltons It is 10 to 25 % as hemodialysis Time consuming requires 24 hours for successful completion PROCEDURE Allows diffusion of toxins from capillaries across peritoneal membrane into dialysate It involves placing a stylet catheter under local anesthesia and surgical insertion of Tenckhoff Dilaysate fluid exchanged 1 to 2 litres per hour

8. HEMODIALYSIS Hemodialysis is a treatment to filter wastes and water from your blood, as your kidneys did when they were healthy. Hemodialysis helps control blood pressure and balance important minerals, such as potassium, sodium, and calcium, in your blood. Hemodialysis initiation is needed for acute illness associated with: Acute kidney injury Uremic encephalopathy Pericarditis Life-threatening hyperkalemia Refractory acidosis Hypervolemia causing end-organ complications (e.g., pulmonary edema ) Failure to thrive and malnutrition Peripheral neuropathy Intractable gastrointestinal symptoms Asymptomatic patients with a GFR of 5 to 9 mL/min/1.73 m² Any toxic ingestion These conditions cause dysregulation and impaired clearance of cytokines (immune response modulators), causing vasodilation, cardiac depression, and immunosuppression leading to end-organ damage, hemodynamic instability , or delaying renal recovery.

9. Hemodialysis is first used in 1913 . Considerations for dialysis include A substance should be such that it can diffuse through dialysis membrane A specific portion of substance should be present in water The pharmacological effect should be directly related to blood concentration Procedure Basic components of hemodialysis include 1 . Blood delivery system 2. Dialyser 3. Method of delivery of dialysate INDICATIONS Those who are not responding to standard measures Stage 4 of coma Severe acid base titrations Severe electrolyte imbalances After heavy metal chelation in patients with renal failure Effective in serious intoxications of li ,phenobarbitone , salicyalates and theophylline Fairly good indications Dialysis may be initiated following exposure to agents Patients despite supportive care : alcohols, amphetamines, anilines, antibiotics , boric acid chlorates and iodides Isoniazid and paraldehyde

10. Poor Indications Paracetmol , anti depressants and anti histamines , belladonna alkaloids , benzodiazepines and opiates , Digitalis and phenothiazines COMPLICATIONS infection Thrombosis Hypotension Air embolism Bleeding

11. It is used for treatment of patients with toxicity caused by lithium , toxic alcohols , salicyaltes and theophylline Vascular access is attained by femoral vein It is performed using a doube lumen catheter made of silicon, polyethylene , Teflon Blood is pumped through lumen Blood flow rates can be as high as 450-500ml/min Anticoagulation with heparin is required A typical heparin dose is 4000 to 5000 units followed by 400-500 units hourly In poisoned patients dialysis is performed for 4 to 8 hours In sodium bicarbonate based dialysate with potassium concentration ¾ meq /l following at 600-800mL/min is sufficient

12. Clearance is calculated by Clx = Qp×ER Qp = Qb × (1-Hct) Plasma flow rate ER =Cin –Cout / cin ×100

13. HEMOPERFUSION An arteriovenous shunt or double lumen venous catheter inserted into patients vascular tree A bolus of heparin is injected into arterial line and heparinization is continued Blood is pumped through cartridge containing sorbent , activated charcoal or carbon The sorbent is coated with a very thin layer of polymer membrane Cellulose acetate Poly HEMA Improves biocompatibility and helps prevent charcoal embolization Cartridge changed after 2 hours of use Hemoperfusion after 4 o 6 hours at flow rates of 250 to 400 ml/min The various methods of eliminating absorbed poisons Forced diuresis Hemo dialysis Peritoneal dialysis Plasma pheresis Cardiopulmonary bypass

14. COMPLICATIONS Bleeding Air embolism Infection Thrombocytopenia Hypocalcemia

15. PLASMA PHERESIS It is a technique of separating cellular blood components from plasma Used in overdose of theophylline , carbamazepine , amanita, mercury, hemlock COMPLICATIONS Bleeding disorders Hypercoagulation Anaphylaxis Fluid overload Infecction Citrate toxicity Convulsions Metabolic acidosis

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