Today3 [Compatibility Mode]

8/3/2019 Today3 [Compatibility Mode]

1/62

14/10/2011Prof Dr Ashraf M. Emara


2/62

Prof in Forensic Medicine and Clinical Toxicology

Department

AND



3/62


4/62

OUTLINE OF LECTURE

Definitions and classification of poisons

Phases of poisoning

Factors affecting the severity of poisoning

Diagnosis

Treatment


5/62



6/62

Enhancement of eliminationEnhancement of elimination

Lung (Oxygen + CO2)

Intestine (purgatives)

Lung (Oxygen + CO2)

Intestine (purgatives)

e repeate oses o . .

Kidney (Diuresis + dialysis)

e repeate oses o . .

Kidney (Diuresis + dialysis)



7/62

dose activated charcoal-Repeat

Dose: 20-30 or 0.5-1 k ever 4 hours are

given orally or via gastric tube.



8/62

dose activated charcoal-RepeatReduces the blood concentration of a toxin by

either: Interrupting enterohepatic or enteroenteric circulation

(e.g. morphine, dapsone, digitoxin, carbamazepines, and

TCA).



9/62

dose activated charcoal-RepeatReduces the blood concentration of a toxin by

either:

Allow toxin diffusion passively from the

(gasterointestinal dialysis) as theophylline.

Adsorption ofdrugs still present in the gut

as drugs forming concretions (salicylate),SR preparations (theophylline), and drugs

slowing the GIT motility (anticholinergics).



10/62

dose activated charcoal-RepeatIndications:

Shorten the half-life of:

Carbamazepine

DigitoxinPhenytoin

Phenobarbital

Salicylate

Theophylline.



11/62

dose activated charcoal-RepeatAdverse effects:

Serious fluid and electrolyte disturbance

secondary to large-volume diarrhea, especially

-

used.

It should not be used in patients with ileus or

obstruction.



12/62

DiuresisDiuresis

Fluid

Osmotic

Fluid

Osmotic

orce a a ne + ac corce a a ne + ac c



13/62

DiuresisDiuresis



14/62

Indications of forced diuresis

The poison excreted mainly in urine.

Low protein bound.

Weak acid or weak alkali.



15/62

Contraindications of forced diuresis

The poison not excreted in urine in active

form.

Shock.

Heart ai ure. Renal dysfunction.

The poison produces pulmonary edema.

Lack facilities to monitor plasma electrolytes

level.



16/62

Alkaline dieresis Salicylate, lithium, meprobamate and

phenobarbital are weak acids. By promoting an alkaline urine (PH 7-8),

Drugs wi ecome more ionize in t e istatubular lumen, which will slow tubular re-

absorption and allow a larger fraction of the

drug to be excreted without being reabsorbedback into the body.



17/62

Alkaline dieresis Give sodium bicarbonate 1-2 mEq/kg in 1L

saline / hour every 3-4 hours followed byinfusion of 500 cc dextrose 5% and saline

.

Correct hypokalemia by adding 10 20 mEq/L

IV.

It enhances elimination of polar drugs by iontrapping.

Requires normal renal.14/10/2011Prof Dr Ashraf M. Emara


18/62

Alkaline dieresis

Maintain: Urine pH at 7-8.

- .

Blood pH at 7.35-7.45.

Electrolytes and correct any abnormality (e.g.

hypokalemia).



19/62

Alkaline dieresis

Indications: Salicylate overdose.

.

Lithium overdose.

Poisons producing hemolysis or

rhabdomyolysis.



20/62

Alkaline dieresisAdverse effects:

Fluid overload. Acid-base abnormalities (alkalosis).

ectro yte a norma t es e.g. ypo a em a,hypernatremia).



21/62

DialysisDialysis

The poison moves against concentration

gradients across semipermeable membranes

t roug us ng: Physiologic membrane (peritoneum)

Artificial membrane (hemodialysis).



22/62

DialysisDialysis



23/62

DialysisDialysis

HemodialysisHemodialysis

hemoperfusion

Peritoneal

hemoperfusion

Peritoneal



24/62

HaemodialysisHaemodialysis



25/62


Drugs and toxins flow passively across the

semipermeable membrane down aconcentration gradient into a dialysate

.

electrolyte abnormalities can be corrected

concurrently.



26/62



27/62

Indications Hemodialysis is preferred for salicylate,

phenobarbital, ethanol, and methanol whichhave the following characters:

.

Low lipid solubility (high water solubility).

Low volume of distribution.

Low plasma protein binding.



28/62

Adverse effects Hemorrhage (secondary to anticoagulation).

Hypotension.

Hepatitis, AIDS and other nosocomial

in ections. Thrombosis at the site of venous access.



29/62




30/62

Peritoneal DialysisPeritoneal Dialysis



31/62


Dialysate fluid is infused into the

peritoneal cavity through a transcutaneous

catheter and drained off, and the procedure is

repeate w t res a ysate.The gut wall and peritoneal lining serve as

the semipermeable membrane.



32/62


Indications: The same as hemodialysis.

NB: Peritoneal dial sis is easier to er orm than

hemodialysis or hemoperfusion, but it is onlyabout 10 15% as effective.



33/62




34/62

HaemoperfusionHaemoperfusion



35/62


During hemoperfusion, blood is drived to pass

through a cartridge coated with activatedcharcoal to which toxic agents in the blood

.

to the patient.

Anticoagulation with heparin is necessary.

Calcium & glucose monitoring should be doneas they may be adsorbed to charcoal.



36/62


Indications:

Not limited by protein binding, molecularweight or water solubility.

It is the referred method for theo h lline

paraquate, carbamazepine, phenytoin,phenobarbitone which have the following

characters:

Adsorbed by activated charcoal.

Low volume of distribution.



37/62


Adverse effects: Similar to those of

hemodialysis in addition to the following:

Thrombocytopenia.

Leucopenia.

Hypoglycemia. Hypocalcemia.



38/62

Hemoperfusion

Blood

ARTERY

or

VEINVEIN

Return

Uses hemodialysis machine - but runs blood directlythrough a charcoal- or sorbent-containing filter

rom

patientto

patient


39/62

Physiological antidotesNeutralise poison

Physiological antidotesNeutralise poison

Mechanism:

Antagonism

em ca n ng Immunological binding

Competition of enzyme



40/62

Antidotes (ANTAGONISING THE EFFECTS OF THE POISON

Antidote PoisonN-acetylcysteine acetaminophenatro ine or ano hos hate

Ca gluconate or Ca chloride Calcium channel blockersCyanide kit cyanide

Deferoxamine Iron

Fab digoxin DigoxinDimercaprol (BAL) Arsenic, mercury, lead


41/62

AntidotesAntidote poison

ethanol MeOH, et glycolflumazenil Benzodiazepine

Fomepizole MeOH

glucagon -blocker, CCB

Methylene blue methemoglobin

naloxone opioidsphysostigmine anticholinergic

pralidoxime organophosphate

pyridoxine isoniazid

Sodium bicarbonate TCA, cocaine, salicylates


42/62

Supportive treatmentSupportive treatment

Coma

Acid base disorders

Dehydration

Rhabdomyolysis



43/62

ComaComa

CirculationRespirationReflexes

response

Pain

response

Conscious

level

Stage

NormalNormalIntactArousableA sleep0

NormalNormalIntactWithdrawsComatoseI

NormalNormalIntactNoneComatoseII

NormalNormalAbsentNoneComatoseIII

ShockCyanosisAbsentNoneComatoseIV



44/62

Causes of ComaCauses of Coma

General CNS depressants: Barbiturates

Benzodiazepines, alcohols. - Cellular hypoxia: Carbon monoxide, Cyanide,

, .

- Sympatholytic agents: Clonidine,

Tetracycline, Methyldopa, Opiates.

- Others: Hypoglycemic agents, Disulfiram,Salycylates.



45/62

Treatment of ComaTreatment of Coma

As acute poisoning:

Give:

Dextrose (50%, 50ml IV) to correct hypoglycemia.

Thiamine (100 mg IV), to correct suspected

vitamin deficiencies.

Naloxone (0.4 mg IV) to correct respiratory

depression in acute opiate toxicity.

Perform CT scan and lumbar puncture & CSFculture to exclude traumatic, pathological or

infectious coma.14/10/2011Prof Dr Ashraf M. Emara


46/62

Hypothermia



47/62

Treatment Maintain the airway and assist ventilation, and

administer supplemental oxygen. Treatment of the cause (e.g. hypotension).

I t e patient is not in car iac arrest, rewarm

slowly using blankets, warm IV fluids, and

warmed-O2 inhalation to prevent

arrhythmias.



48/62

Hyperthermia


Hyperthermia


49/62

Hyperthermia

Malignant hyperthermia (inherited disorder)

causes Severe hyperthermia

Rigidity

After exposure to certain anesthetic agents (e.g.

halothane and succinylcholine).


Hyperthermia


50/62

Hyperthermia

Treatment:

A & B.

Treatment of the cause (e.g. seizures).

Shivering can be avoided by diazepam.

Cooling (external & internal core). Neuromuscular paralysis (using

nondepolarizing agent) together with,

endotracheal intubation and mechanical

ventilation is useful for severe cases.


Hyperthermia


51/62

Hyperthermia

Treatment:

Specific drugs:

Bromocriptine in neuroleptic malignant syndrome


Rhabdomyolysis


52/62

Rhabdomyolysis

Causes:

Prolonged immobilization on a hard surface

Excessive seizures

Hyperthermia

Direct cytotoxic effects (e.g. carbon monoxideand some snake venoms).


Rhabdomyolysis


53/62

Rhabdomyolysis

Muscle tenderness

Pigmenturia with urine that is orthotoluidine

(Hematest) positive with few or no intact redblood cells.

Renal failure Elevated serum creatine phosphokinase (CPK)

level.


Rhabdomyolysis


54/62

Rhabdomyolysis

Treatment:

Maintain urine flow rate (35 mL/kg/h) with

intravenous fluids. If oliguria occurred, consider a bolus of

mannitol.

Alkalinize the urine by sodium bicarbonate

(acidic urine promotes deposition of myoglobin

in the tubules). Hemodialysis may be needed, for acute renal

failure.14/10/2011Prof Dr Ashraf M. Emara


55/62

Poison Prevention Strategies

Keep all house hold poisons separate from

food. Keep all products in their original container.

A ways rea a a e s care u y e ore using

the product.

Never take or give any medication in the dark.

Dispose all toxic and medicinal products in asafe and proper manner.



56/62


P i P i S i


57/62


Encourage periodic home hunts and dispose

of old medication. Never refer to medicine or vitamins as candy.

Teac c i ren never to ta e me ication

unless given by adult they know.

Once a child has been poisoned. Be alert for

repeated episodes. Teach children not eat plants.



58/62


P i P ti St t i


59/62


Keep all drugs or toxic substances out of

children sight & reach; use cabinet locks.

Keep the poison control center number at

each telephone. Tanta university hospitals, Emergency

Hospital.

Emergency line : 0185103132Administrative line : 3350373



60/62



61/62



62/62


Documents

Today3 [Compatibility Mode]