A STUDY ON THE CORRELATION OF SEVERITY OF ORGANOPHOSHORUS POISONING WITH SERUM AMYLASE AND CPK LEVEL AND PREDICTION OF
VENTILATORY SUPPORT REQUIREMENT
& MORTALITY
DISSERTATION SUBMITTED FOR M.D GENERAL MEDICINE
BRANCH – I REG.NO: 201711124
MAY 2020
THE TAMILNADU
DR.M.G.R. MEDICAL UNIVERSITY
CHENNAI, TAMILNADU
CERTIFICATE FROM THE DEAN
This is to certify that this dissertation entitled “A STUDY ON THE CORRELATION OF SEVERITY OF ORGANOPHOSHORUS POISONING WITH SERUM AMYLASE AND CPK LEVEL AND PREDICTION OF VENTILATORY SUPPORT REQUIREMENT &
MORTALITY” is the bonafide work of Dr.YAGNESHWARARAJA.T
in partial fulfillment of the university regulations of the Tamil Nadu Dr. M.G.R. Medical University, Chennai, for M.D General Medicine
Branch I examination to be held in May 2020
Dr. K. VANITHA MD., DCH., THE DEAN,
Madurai Medical College and Government Rajaji Hospital, Madurai
CERTIFICATE FROM THE HOD
This is to certify that the dissertation entitled “A STUDY ON THE CORRELATION OF SEVERITY OF ORGANOPHOSHORUS POISONING WITH SERUM AMYLASE AND CPK LEVEL AND PREDICTION OF VENTILATORY SUPPORT REQUIREMENT &
MORTALITY” is the bonafide work of Dr.YAGNESHWARARAJA.T
in partial fulfillment of the university regulations of the Tamil Nadu Dr. M.G.R. Medical University, Chennai, for M.D General Medicine
Branch I examination to be held in May 2020.
Dr. M. NATARAJAN M.D., Professor and HOD,
Department of General Medicine, Government Rajaji Hospital, Madurai Medical College, Madurai.
CERTIFICATE FROM THE GUIDE
This is to certify that the dissertation entitled “A STUDY ON THE CORRELATION OF SEVERITY OF ORGANOPHOSHORUS POISONING WITH SERUM AMYLASE AND CPK LEVEL AND PREDICTION OF VENTILATORY SUPPORT REQUIREMENT &
MORTALITY” is the bonafide work of Dr.YAGNESHWARARAJA.T
in partial fulfillment of the university regulations of the Tamil Nadu Dr. M.G.R. Medical University, Chennai, for M.D General Medicine
Branch I examination to be held in May 2020.
Dr. M. NATARAJAN M.D., Professor and HOD,
Department of General Medicine, Government Rajaji Hospital, Madurai Medical College, Madurai.
DECLARATION
I, Dr. YAGNESHWARARAJA.T solemnly declare that, this dissertation “A STUDY ON THE CORRELATION OF SEVERITY OF ORGANOPHOSHORUS POISONING WITH SERUM AMYLASE AND CPK LEVEL AND PREDICTION OF VENTILATORY SUPPORT REQUIREMENT & MORTALITY” is a bonafide record of work done by me at the Department of General
Medicine, Govt. Rajaji Hospital, Madurai, under the guidance of Dr. M. NATARAJAN M.D., Professor, Department of General Medicine,
Madurai Medical college, Madurai.
This dissertation is submitted to The Tamil Nadu Dr. M. G. R. Medical University, Chennai in partial fulfillment of the rules
and regulations for the award of M.D Degree General Medicine Branch-I examination to be held in May 2020.
Place: Madurai Date: Dr. YAGNESHWARARAJA.T
ACKNOWLEDGEMENT
I would like to thank Dr. K. VANITHA MD., DCH., The Dean, Madurai Medical College, for permitting me to utilize the hospital facilities for this dissertation.
I also extend my sincere thanks to Dr. M. NATARAJAN M.D., Head of the Department and Professor of Medicine for his valuable guidance and encouragement during the study and also throughout my course period.
I express my sincere thanks to our beloved professors Dr.M.NATARAJAN M.D., Dr.G.BAGHYALAKSHMI M.D., Dr. J.SANGUMANI M.D., Dr.C.DHARMARAJ M.D., Dr.DAVID
PRADHEEP KUMAR M.D., DGM., MRCP., Dr.S.C.VIVEKANANDHAN M.D., Dr.K.SENTHIL, M.D., Dr. V.N.ALAGA VENKADESAN M.D., for their interest in clinical
teaching and constant support for me.
I express my sincere thanks to Dr.P. MOHANKUMARESAN, M.D., Professor and HOD of Bio-chemistry for permitting me to utilize the facilities in the department for the purpose of this study and guiding me with enthusiasm throughout the study period.
I also offer my special thanks to the Assistant Professors of my Unit Dr.P.S.VALLIDEVI M.D., Dr.P.SRIDHARAN M.D., Dr.D.VASANTHA KALYANI M.D, DCP., for their help and
constructive criticisms.
I wish to acknowledge all those, including my other postgraduate colleagues and my parents who have directly or indirectly helped me to complete this work with great success.
Finally, I thank the patients who participated in the study for their extreme patience and co-operation without whom this project would have been a distant dream.
Above all, I thank The Lord Almighty for his kindness and benevolence.
CONTENTS
S.NO TITLE PAGE NO.
1 INTRODUCTION 1
2 AIMS AND OBJECTIVES 4
3 REVIEW OF LITERATURE 5
4 MATERIALS AND METHODS 66
5 OBSERVATIONS AND RESULTS 70
6 DISCUSSION 87
7 LIMITATIONS OF THE STUDY 93
8 CONCLUSION 94
9 ANNEXURES
BIBLIOGRAPHY PROFORMA ABBREVATIONS MASTER CHART
ETHICAL COMMITTEE APPROVAL LETTER ANTI PLAGIARISM CERTIFICATE
Introduction
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1. INTRODUCTION
Organophosphorus poisoning is now an epidemic proportion in maximum parts of the world. It is most popular and most widely used insecticides in India. They have assumed considerable importance in many parts of the world. High fatality rate is mainly due to availability of these compounds and lack of appropriate medical facilities. A Socio- cultural factor also has its main role in choosing these compounds as a popular self-poison.
An estimation done by World Health Organization (WHO) tells that every year around 0.3 million people expire because of various poisonings and among them pesticide poisoning contributes more than 2,20,000 deaths in developing countries per year. In India reports says poisoning as suicidal method is approximately around 90% with fatal rate more than 10%. Accidental exposure is around 8% to 10% and homicidal incidence is < 1%.
In India particularly southern and central part of india – OP Compounds causing more self poisoning death. In northern part aluminium phosphide is the most common cause of death (more than 90%). Organochlorines, Organocarbamates, Pyrethroids are Other pesticides causing self poisoning. Thus morbidity and mortality by toxic
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effects of OP Compounds is so significant contributing a major global clinical burden.
OP compounds over stimulates cholinergic synapses by inhibiting acetyl cholinesterase and butyryl cholinesterase enzymes. Serum cholinesterase level measurement is a gold standard for diagnosis of Organophosphorus poisoning, it’s level decreases in these poisonings.
Still it may fall within the normal range and also measurement of these enzymes is not available routinely in every laboratories and they are so costly also.
Thus cheaper and easily measurable bio-chemical markers are needed in relation with these compounds like creatine phosphokinase and seum amylase. In many animals studies creatine phosphokinase levels offen found to be elevated in these poisoning.
Serum CPK, CPK-MB levels found to be Increased in severe acute OP Poisoning, due to toxic muscle fibre necrosis, persistent depolarization of neuromuscular junction and oxidative muscle cell damage. Increased sympathetic and parasympathetic activity causing myocardial damage and coronary artery spasm. Starts raising in 6 hrs of acute poisoning peaks in 48 hrs, remains elevated for 5-7 days. If the CPK baseline level is high and peaks in 48 hrs pt may go for intermediate syndrome, and can earlier predict it and also the requirement of ventilator support.
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Serum amylase is raised in organophosphorus poisoning secondary to parasympathetic over stimulation causing pancreatic injury and hypersecretion. Opc poison induced hypoxia impairs oxydative phosporylation and ATP production,so starch got hydrolysed,increased sugar is consumed inturn upregulates the alpha amylase genes and produces increased amylase levels.
Serum amylase and Serum CPK level correlate well with severity of Poisoning and better Predictor of ventilator support Requirement. OP Poisoning exposure and science of increased cholinergic activity assists in diagnosing these poisons. Thus treated by antagonizing with atropine or glycopyrrolate and oximes helps in reactivating the enzyme. Always anticipate complications like respiratory failure CNS depression and ventricular arrhythmias and ready to treat.
They are associated with cardiac complications, most of them occurring first few hours of exposure. Major cause for developing these complications are hypoxemia and electrolyte abnormalities. Cardiac complications include hypotension sinus bradycardia, sinus tachycardia and cardiac arrest due to arrythmias. Compounds have been found to cause myocardial necrosis (myocardiotoxicity). They also influence neural dysfunction and brain damage by altering the normal internal milieu which leads to altered level of consciousness in such poisonings.
Aims and Objectives
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2. AIMS AND OBJECTIVES
To assess serum creatine phosphokinase (CPK) level and serum amylase level in OP poisoning
To assess the linear correlation between severity of OP poisoning in relation to respiratory system and levels of serum CPK and amylase levels and predicting Requirement of ventilatory support.
Review of Literature
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3. REVIEW OF LITERATURE
HISTORICAL REVIEW
During the past four decades, more than 35,000 different compounds have been introduced and are being used as pesticides. Of these, organophosphates are the most commonly used compounds globally. They have emerged as leading cause of ill health associated with pesticides all over the world.
Modern investigations of organophosphorus compound date from 1932 when Langean Krugger recorded the synthesis of dimethyl and diethyl phosphofluoridates. They noted that these compounds caused a persistent choking sensation and blurring of vision. This observation led industries to develop organophosphorus compound, first as agricultural insecticides and later as potential chemical warfare agents.
Consequently, during World War II,several toxic compounds were developed and used as nitrogen gases in Germany. In 1991,these very compounds formed the cornerstone of Iraq’s much dreaded chemical warfare arsenal during the Gulf war . Organophosphorus compound first came to India in 1951,to be used as insecticides and in 1962 first organophosphorus poisoning was reported in India.
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1854 -Synthesis of OP compound (TEPP) - by Phillipe de Clermont. Not used actively then.
1930- Gerhard Schrader,German synthesised parathion.His priority shifted to nerve gas agents; used during World War 2
Early 1900 Carbamates were developed in Africa from calabar bean. Physostigmine, used to treat glaucoma
1970s, carbamates were synthesized for pesticidal use.
CMs are preferred for pesticide use over OPs because the former are safer reversible inhibitors of AChE unlike OP.
In 1984, an estimated 4 lakh people were exposed to a toxic methyl isocyanate gas (used in the production of CM pesticides) that leaked from the Union Carbide plant in Bhopal, India.
Annual incidence of acute insecticide poisoning - 3 million (approx.) worldwide.
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CLASSIFICATION INSECTICIDES
These are compounds used to kill or repel insects & related species.
They include
Organophosphorus compounds
Carbamates
Organochlorines
Pyrethroids
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Classification
ALKYL GROUP – HETP, TEPP, OMPP Malathion, Dipterx
ARYL GROUP – Parathion, paraoxon Chlorothion, Diazinon Eketox
WHO CLASSIFICATION
HIGHLY TOXIC MODERATELY
TOXIC
Phosphamidon Malathion
Ethyl Parathion Fenthion
Methyl parathion Temephos
Chloro thiophos Fenithrothin
Carbo phenothion Diazinon
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CARBAMATE GROUP
These insecticides are reversible inhibitors of cholinesterase unlike organophosphates. Commonly used are
1. Aldicarb 2. Carboryl 3.Methiocarb 4.Methonyl 5. Oxamyl 6. Premicarb 7.Thiofanox 8. Propaxur
CHLORINATED INSECTICIDES 1. DDT
2. Gammaxine 3. Hexaphane 4. Aldrin 5. Dialdrin
DDT is most commonly used chlorinated insecticide used to kill flies, mosquitoes, bed bugs etc. Mode of action - acts on motor cortex and cerebellum. Portal of entry - oral, local, inhalational. Symptoms - nausea , vomitting, excitability, vertigo, weakness, muscular tremors, convulsions, tingling in arms and legs,paralysis of legs, pulmonary oedema, death from respiratory failure. Fatal Dose-150 to 160mg/kg body weight around 10.5gm for 70kg adult. Fatal Period- 30min to 4hours.
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STRUCTURE
OP insecticides are anticholinesterase agents; esters, amides or thiol derivatives of phosphoric acid. The R1 and R2 moieties are alkyl or
aryl group and linked by oxygen and sulphur atom to phosphorus R1 O or S
P
R2 RL
Some OP available
Dimethyl compounds (ageing 3.7 hours)
Malathion
Dichlorvos
Dimethoat
Fenthion
Diethyl compounds (31 hrs)
Chlorpyrifos
Diazinon
Parathion
Quinalphos
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TOXICITY RATING
Extremely Toxic (LD50 : 1 to 50 mg/kg) or Highly Toxic (LD50 : 51 to 500 mg/kg)
Eg : Chlorpyriphos , Diazinon , Phenthion , Methyl parathion … Moderately Toxic (LD50 : 501 to 5000 mg/kg)
or Slightly Toxic (LD50 : > 5000 mg/kg)
Eg : Abate, Acephate, Malathion, Temephos …
Autonomic nervous system
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Symptoms and Signs of Organophosphate Poisoning based on receptors Involved:
Cholinesterase
Cholinesterase is an esterase that lyses choline based esters.
Catalyses the hydrolysis of these cholinergic neurotransmitters such as breaking acetylcholine into acetic acid and choline
Location
1. Synaptic cleft 2. RBC
3. Blood Plasma
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Pseudocholinesterase
Cholinesterase which is present in plasma, it is called as Pseudocholinesterase. It is also affected in same manner as like cholinesterase which is present at synaptic cleft. We are measuring plasma cholinesterase or pseudocholinesterase for diagnosis because easy to measure, easily available. 50% reduction in normal values: Diagnostic [baseline values usually NA]. Progressive increase in pseudocholiesterase with treatment.
ANTICHOLINESTERASES
Anticholinesterases are agents which inhibit cholinesterase thereby protecting acetyl choline from hydrolysis. This results in potentiation of cholinergic effects in vivo. They can be classified into
1. Reversible – physostigmine, neostigmine, pyridostigmine, edrophonium,
rivastigmine, donepezil
2. Irreversible – organophosphates and few carbamates.
Anticholinesterases bind to and inhibit a number of enzymes, yet it is their action on the esterase which is of clinical importance.
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Inhibition of Acetylcholinesterases (AchE)
Acetylcholinesterases (AchE) are responsible for cleaving acetylcholine (Ach) to choline and acetic acid by hydrolysis. A potential reaction causes release of acetylcholine into synaptic cleft and Ach readily binds to the receptors in the postsynaptic membrane which leads to the generation of an excitatory postsynaptic potential and propagation of the impulse.
Anti-acetylcholinesterase has two sites namely, anionic and esteric site. Acetylcholine binds to the anionic site on acetylcholinesterases and undergoes hydrolysis in a few seconds. Reversible anti- acetylcholinesterases combine with acetylcholinesterases at the anionic site and this blocks attachment of the substrate.
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MECHANISM OF ACTION
Both compounds are powerful inhibitors of cholinesterase enzyme which is present in neuromuscular junctions and ganglions and responsible of degradation of acetylcholine. Results in accumulation of Ach causes hyperexcitation of voluntary and involuntary muscles with increased secretion altogether resulting in toxic symptoms.
OPC are popularly used insecticides as well as commonly used Poisonous agents in India. They are available as dust, granules or liquids.
Some products need to be diluted with water while some are burnt to make smoke that kills insects. Certain OPC’s are highly toxic & despite early & effective treatment, the mortality following OPC poisoning still ranges around 7-12 %
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How does AChE act?
o The entire process takes about 150 microseconds o True AChE – nervous tissue, surface of RBCs.
o ButyrylChE/PseudoChE- serum, liver.
What do OP do?
Alkyl phosphorylation of Serine-OH group at the esteric site of enzyme.
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Mechanism of toxicity of organophosphorus compounds:
MODE OF ACTION
OPC’s are powerful inhibitors of Acetyl cholinesterase resulting in accumulation of Acetylcholine with continued stimulation of local receptors & eventual paralysis of nerve or muscle. It binds to acetyl cholinesterase molecule at active site & phosphorylate the serine moiety.
The resulting conjugate is more stable & so phosphorylated enzymes degrade very slowly over days to weeks.
Once Acetyl cholinesterase is phosphorylated, an alkyl group is lost from the conjugate and the enzyme gets inactivated permanently.
OPC’s also exert inhibitory action over carboxylic ester hydrolases like
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Chymotrypsin, Butyrl cholinesterase, paraoxonases & non-specific proteases. The delayed Peripheral neuropathy caused by OPC’s is due to phosphorylation of some esterases like Neurotoxic esterase also known as Neuropathy Target Esterase (NTE), that develops 2-5 weeks after acute poisoning.
Pathogenesis
Inhibition of acetyl cholinesterase leads to the accumulation of acetylcholine at cholinergic synapses, interfering with normal function of the autonomic, somatic, and central nervous systems. This produces a range of clinical manifestations, known as the acute cholinergic crisis
PATHOPHYSIOLOGY
The pathophysiological effects of organophosphates result from inhibition of cholinesterase (both RBC and pseudo cholinesterase).These
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are the markers of exposure,acute toxic effects and reflect actual activity at cholinergic nerve terminal. The serum cholinesterase levels are depressed within a short time in acute poisoning. A critical reduction of cholinesterase activity to less than 20% results in severe manifestations of cholinergic overactivity while signs begin to appear when their levels are depressed to 50%.
There are many other causes of decreased cholinesterase levels.
Severe malnutrition, liver disorders, pregnancy, both acute and chronic inflammatory states reduce the enzyme levels. Rarely the levels may be low due to genetic mutations. But the depression in cholinesterase levels is never severe enough to produce signs and symptoms. The enzyme levels slowly returns to normal when the primary disorder is treated.
OP pesticides inhibit acetylcholinesterase at muscarinic and nicotinic synapses by phosphorylation of the enzyme at its active site forming a temporary covalent bond which leads to increased availability of acetylcholine at the synaptic cleft and thereby resulting uncontrolled cholinergic over-activity. Over time, one of the two processes will occur.
The covalent bond may spontaneously cleave leaving the enzyme functional again. This process may take upto1000 hours. Meanwhile the enzyme is prone to “ageing” in its active site in which one of the “R”
group may cleave non-enzymatically, leaving behind a hydroxyl group.
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Once ‘aging’ of the enzyme occurs, the inactivation cannot be reversed because the negatively charged phosphate group of the enzyme cannot be attacked by nucleophile like hydroxyl or oxime anymore. The enzyme is inhibited once for all.
Recovery of a functional pathway must wait until new cholinesterase enzyme is produced,a process that may take weeks. The time it takes for ageing to occur varies according to the specific pesticide, but takes no longer than 48 hours. Clinically the toxic effects of OP agents may persist for more than a week. Oximes slows down “ageing” of the phosphorylated cholinesterase and binds to the OP agent, making it non reactive. This results in cholinesterase regeneration and a rise in serum levels of cholinesterase.
Signs and symptoms of OPC poisoning Four clinical syndromes have been described
1. Acute cholinergic syndrome (most common)
2. Sub acute proximal weakness (Intermediate syndrome) 3. Organophosphate induced delayed neuropathy (OPIDN)
4. Chronic organophosphate induced neuropsychiatric disorder (COPIND)
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Acute Poisoning Cholinergic Excess
Muscarinic effects – Common manifestations include Bronchoconstriction with wheeze & dyspnoea, cough, pul. oedema, miosis,
Excessive Salivation, Lacrimation, Urination, Diarrhoea, GI distress & Emesis. Bradycardia & Hypotension occur following moderate to severe poisoning.
Nicotinic effects - Fasciculations, weakness, tachycardia, hypertension & paralysis. Cardiac arrhythmias & Conduction defects have been noted in severely poisoned patients.
CNS Effects
Restlessness, headache, tremors, delirium, slurred speech, ataxia, convulsions & Coma at later stages. Death usually results from respiratory failure due to weakness of resp. muscles & depression of central respiratory drive. Acute Lung Injury is a common manifestation of severe OPC poisoning. In a given case, there may be tachy or brady- cardia, hypo or hyper – tension. Miosis may not be apparent in early stages.
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A kerosene-like odour is perceptible in these cases since the solvent used in many OPC insecticide is a petroleum derivative(Aromax).
Patients with OPC poisoning & QTc prolongation & those with PVC’s are more likely to develop resp. failure & have poor prognosis & higher mortality rates.
Intermediate Syndrome (IMS)
IMS occurs due to dysfunction of the post-synaptic neuromuscular junction
Pathogenesis unclear. But thought to be due to persistent inhibition of acetyl cholinesterase
IMS develop about 24-96 hours after OPC induced intoxication
Respiratory insufficiency onset of IMS.
The patient is usually conscious.
Muscles innervated by cranial nerves show varying degree of weakness. External ocular muscles are most commonly affected
Weakness is bilateral and symmetrical
Patient cannot raise the head from bed.
There is no sensory impairment.
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Delayed Polyneuropathy
Organophosphorus induced delayed polyneuropathy (OPIDP) occurs following a latent period of 2-4 weeks after exposure by any route. The cardinal symptoms are distal weakness and in some cases paraesthesia in the distal parts of the limbs, foot drops, wrist drop and claw hands are inevitable consequences. Pyramidal signs may appear after a few weeks or few months. Recovery is variable and the condition may be permanent. Severe cases progress to complete paralysis, impaired respiration and death.
Suggested diagnostic criteria include:
Symptoms and signs of polyneuropathy.
Sometimes later pyramidal tract signs
Denervation changes (shown by electromyography).
Reasonable exclusion of other causes.
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Comparison between intermediate syndrome and delayed neuropathy
Intermediate syndrome Delayed neuropathy
Latent period 1-4 days 2-3 weeks
Site of weakness Proximal Distal
EMG Tetanic fade Denervation
Recovery 4 – 18 days 6 – 12 months
OP agents commonly involved
Fenthion, Dimethoate, Monocrotophos
Methamidophos, Trichlorphos, Leptophos
Chronic Poisoning
It usually occurs as an occupational hazard in agricultural workers.
The route of exposure is usually inhalation or through skin contamination.
The main features include Polyneuropathy, drowsiness, confusion, Sheep-Farmers disease
Impairment of vigilance, information processing, psychomotor speed and memory.
Poor performance and perception of speech.
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Increased tendency to depression anxiety and irritability.
A tendency to faster frequencies and higher voltages in EEG.
Extrapyramidal manifestations (dystonia, rest tremors, cog wheel rigidity and chorea-athetosis) may occur four to forty days after organophosphoruspoisoning .Recent studies suggest that Parkinsons disease is more common in patients who report to have had previous exposure to pesticides.
OPC poisoning is associated with variety of sub-acute & delayed onset neurological & psychiatric syndromes, together known as
‘Chronic 0rganophosphate – induced Neuropsychiatric disorder’ . (COPND)
GRADING OF SEVERITY IN OPC POISONING Clinical grading: Based on-
1.Miosis
2.Fasciculation 3.Respiratory Rate 4.Bradycardia
5.Level of consciousness
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Latent poisoning:
Clinically there are no manifestations of poisoning. The measurement of acetylcholinesterase levels in serum is used for diagnosis which is usually about 50-80% of the normal.
Mild poisoning:
Clinically patient experience ‘SLUDGE’ symptoms – excessive salivation, lacrimation, urination, sweating, diarrhea, gastrointestinal cramps and emesis. The levels of serum cholinesterase are reduced to 20- 50% of normal values.
Moderate poisoning
The manifestations are severe that the patient feels generalized weakness, miosis, muscular fasciculations and even difficulty to talk.
Serum cholinesterase levels are 10-20% of normal values.
Severe poisoning:
Patient is usually stuporous or unconscious with marked miosis and loss of pupillary light reflex. Secretions from the mouth and nose, bronchorrhea causing rales in the lungs , shallow respiration and cyanosis are frequently seen in patients with severe poisoning. Serum cholinesterase levels are lower than 10% of normal values.
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However, this proposed grading has proved unworkable in clinical practice because of many varied clinical criteria in different grades, as well as the difficulty in remembering and applying then in acute clinical situation.
The second classification was proposed by Bardin et al and is as follows:- Grade 0 Nil - Positive history
No signs of organophosphorus poisoning.
Grade 1 Mild - Mild secretions, few fasciculations, Normal level of sensorium.
Grade 2 Moderate - Copius secretions, generalized fasciculations, rhonchi,crepitations, hypotension, disturbed level of
consciousness.
Grade 3 Severe - Stupor,PaO2 < 50mmHg, Chest X ray abnormal.
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This study by Bardin et al showed that patients with grade 3 manifestations on admission were associated with increased requirement for mechanical ventilation. The presence of other complications and increased days of ICU stay have been observed in the above patients.
Grading on the basis of cholinesterase values (Biochemical Grading) Red cell cholinesterase activity (% normal)
Mild poisoning –serum cholinesterase levels decrease to 20 – 50%
Moderate poisoning – serumenzyme levels decrease to 10 – 20%
Severe poisoning – when enzyme levels fall less than 10%
Grading of fasciculations
Grading of fasciculation was done by giving score of 1 depending on the presence of fasciculations each to the anterior chest, posterior chest, anterior abdomen, posterior abdomen, right thigh, left thigh, right leg, left leg, right arm and left arm. The total fasciculation score is thus estimated.
DIAGNOSIS
Diagnosis is mainly clinically based on 1.H/o-Ingestion of poison.
2.Characteristic clinical features.
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3.Clinical improvement after atropine/oxime given.
4.Inhibition of cholinesterase activity.
In most patients, a history of exposure to organophosphorus insecticide can be obtained. A container is usually found. History may be denied in attempts of suicide or unavailable in patients who are found unconscious. Organophosphates impart a garlic like odour to the breath, vomitus or faeces .The signs of organo-phosphorus poisoning that are most helpful in diagnosis are miosis and muscle fasciculations. Others include excessive perspiration, salivation, lacrimation and bronchial secretion.
The response to atropine therapy may also be useful aid to diagnosis, with patients who have organophosphorus poisoning showing a tolerance to atropine. There is also failure to produce signs of atropinisation with 1 to 2mg of atropine administered intravenously.
Inhibition of cholinesterase activity (50% reduction considered confirmatory) of the blood is also helpful. Estimation of erythrocyte cholinesterase (acetyl cholinesterase) is theoretically preferred as it reflects the degree of inhibition of synaptic cholinesterase. However, estimation of plasma cholinesterase(pseudo cholinesterase) can be done.
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The various methods of estimating anti-cholinestersae activity are the electrometric method (widely used),the calorimetric method and a titrometric assay.
Estimation of blood sugar and urine acetone can help to rule out diabetic ketoacidosis since it is an important differential diagnosis of OP poisoning, yet OP consumption itself may cause hyperglycemia .Serum amylase level is said to rise and has prognostic significance. X ray chest can clearly show pulmonary congestion and edema indicating the severity of poisoning.
Investigations
Depression of Cholinesterase activity
If the RBC cholinesterase level is less than 50 % of normal, it indicates OPC toxicity. Depression of Plasma cholinesterase level (less than 50%) is less reliable but easier to assay & more commonly done.
P – Nitrophenol test: It is a metabolite of some organophosphates &
excreted in urine. Production of yellow colour on testing confirms its presence.
Thin Layer Chromatography: The presence of Organophosphate in a lavage or vomitus or gastric aspirate sample can be determined by TLC.
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Other Tests of Prognostic Value A. Hyperglycemia
B. Neutrophilic leucocytosis C. Proteinuria / glycosuria D. Blood pH [acidosis]
There may be evidence of Leukocytosis, high Hematocrit, anion – gap acidosis & hyperglycemia. Electrolytes, ECG & pancreatic isoamylase levels need to be monitored in every case. Chest X-Ray may be helpful in Aspiration pneumonitis / Bronchopneumonia.
Reasons of High Glucose Level Hyperglycemia in OP Poison
1. Oxidative stress.
2. Renal Tubular damage.
3. Stimulations of Adrenal Glands.
4. Release of catecholamines.
Differential diagnosis of organophosphate poisoning Acute poisoning
Overdose – opiates, phenothiazine and nicotine
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Venomous arthropod bites – spider and scorpion Venomous snake bite
Mushrooms containing muscarine
Infective causes – pneumonia, sepsis, meningoencephalitis, botulism, Leptospirosis
Neurologic causes – epilepsy, subarachnoid bleeding, subdural hematoma, pontine haemorrhage
Metabolic causes – uraemia, hypoglycemia/hyperglycemia, myxedema coma, thyrotoxic crisis, Reye’s syndrome
Chronic poisoning
Overdose – alcohol, opiates
Infective – gasteroenteritis, irritable bowel syndrome, bronchitis, asthma, chronic fatigue syndrome
Neurological causes – Guillian Barre syndrome, motor neuron disease, depression, polyneuropathies
Metabolic causes – chronic renal failure, thyrotoxicosis TREATMENT
1.Decontamination 2.Care of airway
3.Administration of antidote
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4.Administration of cholinestersae activators 5.General measures
Acute Poisoning Decontamination
Regardless of nature of the compound, they are persistent on the body and clothing. They even penetrate the skin and clothing. Hence, immediate decontamination is mandatory. Clothing is discarded and the patient is mobilized away from the scene. Gentle washing of the body with soap water will help a lot. Do not wash eyes with any additional compounds other than normal saline, Ringer lactate or plain tap water.
Inhalational exposures are treated with removal of offending vapors and by administering oxygen.
In case of Ingestion, Stomach wash to be done. Activated charcoal can be administered. Gastric decontamination is done by gastric lavage. It is ideally started within 30 minutes of exposure for effective decontamination but should never be delayed in those presenting late. If the patient is semiconscious/unconscious, Ryle’s tube aspiration can be done.
Activated charcoal,1g/kg dose every 2-4 hours may be administered to reduce further absorption from the stomach except in
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cases of intestinal obstruction featured by absent bowel sounds and tense, rigid abdomen.
Respiratory failure is the usual cause of death in the acute phase;
resuscitation and artificial respiration may be required immediately.
Mouth-to-mouth respiration should not be attempted. Cardiac arrhythmias include various degrees of heart block and should be managed accordingly.
Antidotes Atropine
Treatment with anticholinergic medication is still the mainstay of treatment and should be started as soon as the airway has been secure.
Full early atropinisation is an essential and simple part of an early management and a delay can result in death from central respiratory depression, bronchospasm, bronchorrhoea, severe bradycardia or hypotension.
Atropine acts as a physiological antidote, effectively antagonizing the muscarinic receptor mediated action. It has virtually no effect against the peripheral neuromuscular dysfunction and subsequent paralysis induced by organophosphorus agent.
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It is a competitive antagonist of Acetylcholine at the muscarinic post-synaptic membrane & in the CNS & blocks muscarinic manifestations of OPC poisoning. However, it has no effect on muscle weakness/paralysis.
Diagnostic Dose Adult - 1 mg iv/im ; Child - 0.25 mg iv/im .
OPC - poisoned pts. are generally tolerant to the toxic effects of Atropine ( dry mouth , rapid pulse & dilated pupils ).
Therapeutic Dose :
Adult: 1-2 mg iv/im ; Child: 0.05 mg/kg iv/im every 15 mins until the endpoint is reached.
Atropine can also be administered as iv infusion after initial bolus at a rate of 0.02 – 0.08 mg/kg/hr. Once the endpoint is reached, the dose should be titrated to maintain the effect for atleast 24 hrs. The maintenance dose is said to be about 10% of the dose needed for atropinisation as continuous infusion and needs to be adjusted according to the toxic features on observation, as per recent API guidelines.
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Atropinisation must be maintained until all the absorbed OPC has been metabolised, which requires around 2-2000 mgs of Atropine over several hours to weeks.
Observation of the patient:
The most important
Follow up every 15 min with five parameter
If recurrence of bronchospasm or bradycardia, give further boluses of atropine
Once the patient settled then follow up hourly for the first 6 hours to check that the atropine infusion rate is sufficient and that there are no signs of atropine toxicity. As the required dose of atropine falls, observation for recurrence of cholinergic features can be done less often (every 2–3 hours)
However, regular observation is still required to spot patients at risk of, and going into, respiratory failure.
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ATROPINE SHEET (tick box if true)
Time/
date
Heart rate
>80
Clear Lungs *
Pupil Size (C/N/D)
Dry axilla
Syst BP
>80
Bowel sounds
A/D/N/I
Confu- sion
Fever (>37.5)
Atropine Infusion (mg/hr)
Bolus given?
Size?
22.30 52 creps+ pinpoint No 90/60 Incre’d No No 2.4mg bolus 22.35 60 creps+ pinpoint No 90/60 Incre’d No No 4.8mg bolus 22.40 82 +/- pinpoint yes 110/60 Normal No No 4mg bolus 22.50 100 wheeze 2mm yes - Decr’d No No 2mg Bolus 23.00 105 clear 3mm yes - D No No 2mg/hr infus’n 23.15 105 clear 3-4mm yes - D No No “ “ 23.32 102 clear “ yes - D No No “ “ 00.30 98 clear “ yes 110/60 D No No “ “ 01.30 85 clear “ yes - D No No “ “ 02.30 72 wheeze “ yes - N/D No No bol 2mg infus’n 02.35 96 clear “ yes - D No No 2.4mg/hr infus’n 02.45 98 clear “ yes - D No No “
0400 102 clear “ yes - D No No “
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PRECAUTIONS WITH ATROPINE THERAPY
A heart rate exceeding 140beats/minute should be avoided.
Atropine must be used carefully in patients with prior cardiac disorders.
Large doses of atropine may cause ST changes in ECG. The cardiac adverse effects of atropine can be effectively countered by using propanolol.
Atropine crosses the blood brain barrier and may cause severe toxic effects such as convulsions, psychosis and coma, which if necessary should be corrected with physostigmine.
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LIMITATIONS OF ATROPINE 1. Has no nicotinic action
2. Has no effect on respiratory centre in presence of severe asphyxia 3. No effect once hypotension develops
4. In the presence of cyanosis, it may precipitate ventricular fibrillation.
Glycopyrrolate
This is a quaternary ammonium compound that can be used as an alternative to atropine. The advantages of glycopyrrolate over atropine are
a. Better control of secretions.
b. Less tachycardia
c. Fewer CNS side effects Pralidoxime
Pyridine - 2 - aldoxime methiodide (2-PAM)
It is usually given alongwith Atropine
It competes for the phosphate moiety of OPC & releases it from the acetylcholinesterase enzyme, liberating the latter & re-activating it.
Dose - 1-2 gm in 100 ml of NS over 30 mins i.v.
This can be repeated after 1 hr and subsequently every 6-12 hrs, for 24-48 hrs .
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Serious intoxication requires continuous infusion of 500 mg/hr in adults.
Maximum dose of 2-PAM should not exceed 12 gms in a 24 - hr period.
WHO currently recommends an initial bolus of atleast 30 mg/kg, followed by an infusion of > 8 mg/kg/hr.
Plasma concentration of atleast 4 mg/L may be necessary for 2- PAM to be effective.
Adverse effects - Rapid administration can cause tachycardia, laryngospasm and even cardiac/respiratory arrest.
Other effects include vertigo & drowsiness.
PAM
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PAM is available as chloride, iodide, meslyate and methyl sulphate salts .The chloride salt is more stable than iodide in dry state and is preferred for intramuscular use.
The major pharmacological action of oximes is to reactivate anticholinesterase by removal of phosphate group bound to the esteric site .This action occurs shortly after poisoning and inhibition of the enzymes, after which the enzyme ages and becomes more firmly bound to esteric site. Oximes should be given as soon as possible before aging takes place.
They are most effective if given within 6 hours of poisoning, but beneficial response is seen upto 24 hours of poisoning.
The therapeutic effects of oximes seemed to depend on the plasma concentrations of the organophosphorous agent with the benefit being, minimal at high concentrations of organophosphorous in the
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blood.Pralidoxime does not cross the blood-brain barrier whereas obidoxime does.
Adverse effects of therapeutic doses of PAM in humans have been absent or minimal and may not be evident unless plasma levels are greater than 400 mg/ml. Transient dizziness, blurred vision and elevation in diastolic blood pressure may be related to the rate of administration.
Rapid i.v. administration has produced sudden cardiac and respiratory arrest. Paradoxically high doses of pralidoxime may cause neuromuscular block and other effects including inhibition of anticholinesterase. High frequencies of cardiac arrhythmias were observed in patients who received high cumulative doses of atropine and obidoxime.
Obidoxime
Currently obidoxime has been introduced. It crosses blood brain barrier more than pralidoxime. Where obidoxime is available, a loading dose of 250 mg is followed by an infusion giving 750 mg every 24 hours SUPPORTIVE THERAPY
Diazepam
Addition of Diazepam to Atropine & 2-PAM improves survival by reducing the risk of seizure-induced brain & cardiac damage.
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Dose: 5-10 mg iv slowly every 15 mins, upto a maximum of 30 mg.
If Diazepam is ineffective, Phenytoin or Phenobarbitone can be used instead.
Phenytoin
Phenytoin is also used to treat seizures associated with organophosphate poisoning. The usual dose is 10-20 mg/kg.It is given at the rate of 50 mg/min through intravenous route. Patient must be monitored for cardiotoxicity.
Fluoride
Fluoride and atropine combination has a greater antagonistic effect than atropine monotherapy. The use of fluoride was tried following observations from workers of factories dealing with fluoride compounds.
They were found to have higher levels of cholinesterase level in blood.
Magnesium
Kiss and Fazekas reported that intravenous magnesium sulfate can be used successfully to treat ventricular arrhythmias. Magnesium primarily antagonizes the inhibition of sodium-potassium ATPase by organophosphates.
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Other supportive therapies DIURETICS
Coramine or Dextrose saline for collapse
Bronchodilators to improve respiration
Mechanical ventilation if necessary Respiratory stimulants
Respiratory stimulants are contraindicated in the management of organophosphorus poisoning especially when the patient has features of neuromuscular weakness, bronchospasm and convulsions.
Other measures
Dialysis of blood against activated charcoal (hemoperfusion) is effective in demeton-S-methyl sulphoxide, dimethoate and parathion poisoning. Prompt improvements have been reported following repeated injections of purified lyophilized human cholinesterase.
Resealed cells containing a recombinant phosphodiesterase provided protection against the lethal effect of paraoxon.
Phosphodiesterase hydrolyses paraoxon to the less toxic 4-nitrophenol and diethylphosphate. This enzyme was encapsulated into carrier erythrocytes by hypotonic dialysis with subsequent resealing and
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annealing. The encapsulated enzyme was found to persist longer and possess much greater efficacy. When these cells were administered in combination with pralidoxime chloride and atropine, a marked synergism was observed .The use of fresh plasma and exchange transfusions are of little value.
Corticosteroids, camphor, potassium chloride, clonidine and vitamin C have been used with varying degree of success. However all these regimens need further evaluation.
Intermediate Syndrome - Management
Respiratory failure is the cause of death in patients with intermediate syndrome. Early identification and effective management of respiratory failure is the cornerstone in the treatment of IMS. Patients are observed for signs of respiratory failure and facilities for ventilatory care are made available. Arterial blood gas analysis is helpful in monitoring and weaning the patients from ventilator support. Diazepam 10 mg intravenous doses may be useful in anxious or restless patients on ventilator.
Management of Delayed Neuropathy
No specific treatment has been fruitful. Physiotherapy and exercises are tried with variable success. Lay a towel soaked with water over the patient's chest and place in a fan's airflow.
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Benzodiazepines
Benzodiazepines are usually given intravenously as required for agitation or seizures—with doses starting at:
5-10 mg diazepam (0.05-0.3 mg/kg/dose), lorazepam 2-4 mg (0.05-0.1 mg/kg/dose), or midazolam 5-10 mg (0.15-0.2 mg/kg/dose) Active Cooling and Sedation
COMPLICATIONS OF OP POISONING Respiratory Failure
Management of respiratory failure represents the corner stone of treatment.
Artificial ventilation should be started at the first sign of respiratory failure.
For pulmonary edema, high concentration 02 and diuretic should be used.
Morphine and aminophyline should be avoided.
Broad spectrum antibiotic is used as prophylactic measure for aspiration pneumonia.
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The pathogenesis is multifactorial and related to aspiration of gastric contents, excessive secretions in the airways, pulmonary infections, pneumonia, septicemia and development of ARDS.
Respiratory consequences of muscarinic overstimulation including rhinorrhoea, bronchorrhea, broncho-constriction and laryngeal spasm contribute to respiratory failure. These are often combined with nicotinic effects such as respiratory muscle weakness and paralysis (including paralysis of tongue and nasopharynx).
Central depression of respiratory centre occurs following cholinergic overstimulation of synapses in the brain stem and is a prominent cause of hypoxia, respiratory failure and death in the early period of acute organophosphorus poisoning.
Peripheral neuromuscular block producing respiratory muscle weakness and paralysis as well as the recently described intermediate neuropathy contributes to the development of respiratory insufficiency at a later stage.
Sudden cardiovascular collapse is often the first indication of unsuspected or incipient respiratory failure, a presentation that is associated with a high mortality.
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The development of pneumonia is the most important cause of delayed respiratory failure after organophosphorus poisoning and this occurs in upto 43% of the patients. Upto 80% of patients with pneumonia had respiratory failure, majority of these could be diagnosed within 96 hours of poisoning.
TREATMENT OF RESPIRATORY FAILURE WITH MECHANICAL VENTILATORS
Clinical factors influencing the decision to initiate mechanical ventilation in acute respiratory failure are
• Evidence of fatigue of respiratory muscles (e.g., weak and ineffective respiratory effort, paradoxical abdominal movement)
• Altered consciousness
• Circulatory collapse – fall in blood pressure and urine output
• Inability to expectorate secretions
Failure of ventilation is primarily treated by mechanical ventilation. Acute failure of ventilation can be treated non-invasively, provided respiratory acidosis is not life threatening. The usual approach is non-invasive positive pressure ventilation via a tight fitting facemask.
Failure of oxygenation is treated with supplemental oxygen to raise the inspired oxygen concentration (FiO2). Low flow oxygen delivery systems (Nasal prongs, venture face- masks) do not attempt to satisfy
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inspiratory flow requirements completely; room air is entrained diluting the effective FiO2.
When low flow or non invasive supplemental oxygen systems fail to sustain adequate PaO2, further intervention (intubation, mechanical ventilation) is needed. Intubation allows addition of positive end expiratory pressure (PEEP) to recruit collapsed alveoli, increase functional residual capacity and improve gas exchange.
PEEP is typically 5-15 cm of water but depending on clinical circumstances, it must be titrated carefully to avoid decrease in venous return and cardiac output or c pulmonary barotraumas that could result in pneumothorax.
Severe uncompensated hypoxemia despite non invasive treatment requires endotracheal intubation and conventional positive pressure ventilation. During intermittent positive pressure ventilation (IPPV) the work of breathing is taken over as augmented by mechanical ventilator.
All ventilators deliver a predetermined volume or pressure but there are many variations and refinements.
The timing of the inspiratory and expiratory phase can be adjusted and positive pressure can be administered during expiration (PEEP).
Ventilation may be provided totally by the machine or the patient can
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inhale some or all breaths. This facilitates transition from fully supported ventilation to spontaneous breathing. Ventilation can be delivered invasively or non invasively.
PEEP may be useful in patients with reduced lung compliance (stiff lungs) because it improves gas exchange and reduces the work of breathing. In patients with stiff lungs, addition of PEEP allows a reduction of FiO2 thereby reducing risk of oxygen toxicity. It also has a beneficial effect on the lung mechanics because it shifts tidal breathing on to a more compliant part of the pressure-volume curve.
In patients with incomplete alveolar emptying during expiration, the pressure in the alveoli at end expiration remains positive during spontaneous breathing; this is termed ‘intrinsic PEEP’. This positive pressure must be overcome before inspiratory flow can occur and respiratory work is wasted decompressing gas; this is so called
‘Inspiratory threshold load’ can be counterbalanced by the addition of extrinsic c PEEP during ventilation.
Tracheostomy can be inserted percutaneously in an ICU. It reduces the need for sedation, promotes laryngeal competence and may be helpful in weaning by reducing the wasted ventilation of the anatomic dead space.
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Weaning of the patients from assisted to spontaneous ventilation is achieved by synchronized intermittent mechanical ventilation or by pressure support ventilation or spontaneous breathing on a T piece.
Prevention
Preventive measures should be considered at all the levels of the chain of insecticide movement through the environment-formulation, manufacture, mixing application and disposal.
Psychiatric counseling for prevention of second episode should always be given. General counseling and drug therapy for depression should be added. Strict guidelines should be adopted during transport and storage to prevent contamination of food, clothing, drugs, toys, cosmetic and furnishing.
OTHER EFFECTS OF ORGANOPHOSPHORUS INTOXICATION Altered immunity to infection
In 1974,Bellin and Chow suggested that organophosphorus agents might have an effect on the human immune system. Casali et al demonstrated that parathion suppressed both the primary IgM and IgG response to sheep erythrocytes in mice.
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Newcombe showed an increased incidence of lympho-proliferative disorders associated with impaired natural killer cell and cytotoxic T-cell function. Murray et al reported influenza like symptoms in 23 patients after occupational exposure to organophosphorus compounds.
Changes in metabolism and endocrine activity
In animal experiments, changes in the diurnal pattern of plasma ACTH have been reported following organophosphorus poisoning.
Nicotinic receptors also function in brain pathway that increases the release of several pituitary hormones including vasopressors, ACTH and prolactin. In man, nonketotic hyperglycemia may occur.
Effects on Reproduction
There is a report of termination of pregnancy following organophosphorus poisoning during the first trimester. In experimental animals, organophosphorus poisoning during pregnancy cause pre- and postnatal death and congenital abnormalities such as vertebral deformities ,limb defects , polydactyly and cleft palate.
Gastro Intestinal effects
Profuse diarrhea for 2 to 5 days after ingestion of organophosphorous insecticides has been reported.
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Renal effects
Immune complex neuropathy with renal dysfunction and massive proteinuria can occur several weeks after malathion exposure. C3 levels marginally decrease and renal dysfunction resolves spontaneously after 1 month.
Temperature Regulation
After exposure to most organophosphorus compounds, a marked hypothermia response lasting up to 24 hours has been demonstrated.
Follow up of the patient 1. Vital signs
2. Signs of Atropinisation 3. Effect of oxime
4. Toxicity of atropine and oxime 5. RBC and plasma AChE level
6. Recurrence of symptoms on withdrawal of antidote 7. Restart the treatment promptly if recurrence occurs 8. Patient’s general condition
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Cause of Death in OPC poisoning 1. Immediate death
-Seizures.
-Complex ventricular arrhythmias.
2. Death within 24 hours
- Acute cholinergic crisis in untreated severe case -Respiratory failure.
3. Death within 10 days of poisoning - intermediate syndrome.
4. Late death:
- Secondary to ventricular arrhythmias, including Torsades de Pointes, which may occur up to 15 days after acute intoxication.
Prognosis of Organophosphorus Insecticide Poisoning
Deaths usually occur within the first 24 hours in untreated cases and within 10 days in treatment failure cases. If there has been no anoxic brain damage, recovery will usually occur within 10 days, although there may be residual sequelae.
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Factors related to death in OPC poisoning
Amount ingested
Delay in hospitalization
Delay in starting treatment
Neglected
Lack of standardized treatment protocol
Atropine toxicity
Lack of frequent monitoring
Lack of ICU support including financial constrain
Treatment seeking behavior Autopsy features
External
• Characteristic odour (Kerosene-like)
• Frothing at mouth & nose
• Cyanosis at extremities & constricted pupils Internal
• Congestion of GI tract
• Pulmonary & Cerebral oedema
• Generalised visceral congestion
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SERUM CHOLINESTERASE AND SEVERITY OF OP POISONING
The definitive laboratory diagnosis of organophosphorus compound poisoning is the measurement of enzyme activity. Many methods are available to determine the levels of acetylcholinesterase and butrylcholinesterase. The commonly used one is the measurement of catalytic activity.
RBC Cholinesterase level less than 50% of normal indicates organophosphate toxicity. It is more reliable than serum cholinesterase.
Disadvantages are many individuals do not possess a known baseline level and a very low cholinesterase level not always correlate with clinical illness. A false depression of RBC cholinesterase level is seen in pernicious anemia, haemoglobinopathies, anti – malarial treatment and oxalate tube collected blood. Elevated levels seen in reticulocytosis due to anemias, hemorrhage or treatment of pernicious anemia or megaloblastic anemias.
Fall of plasma cholinesterase level to < 50%, is a indicator of OP toxicity but less reliable. It is more commonly done as it is easier to assay. Depression more than 90% indicates severe poisoning usually associated with mortality. It can be falsely low in neoplasia, malnutrition and infections, cirrhosis, chronic debilitating conditions and MI. In pregnancy it will be generally lower and reverts to normal after 6 weeks
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of postpartum. But RBC cholinesterase may be significantly higher in pregnant women. Phosmet and dimethoate selectively inhibits RBC Cholinesterase. Phosdrim and chlorpyrifos selectively inhibits plasma psuedocholinesterase.
To estimate cholinesterase level blood should be collected only in heparinised tubes otherwise samples can be frozen. Plasma cholinesterase usually recovers in few days to weeks. But RBC cholinesterase recovers in several days to 4 months.
Creatinine phosphokinase (CPK)
It catalyses creatine to creatine phosphate. Normal serum value:
15-100 U/L for males & 10-80 U/L for females. CPK consists of 3 isoenzymes.
Each isoenzyme of CK is a dimer. Molecular weight of 40 kD.
The subunits are called B for brain (chromosome -14) & M for muscle (chromosome -19)
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It is an important enzyme in energy metabolism. Immediate source of ATP in contracting muscle.
Three Iso-enzymes are separated by electrophoresis.
CPK-1 (also called CPK-BB) is found mostly in the brain & lungs.
CPK-2 (also called CPK-MB) is found mostly in the heart.
CPK-3 (also called CPK-MM) is found mostly in skeletal muscle.
Creatine phosphokinase isoenzymes
ISOENZYMES SUB-UNIT TISSUE % IN
SERUM CK1
Fast moving BB Brain 1
CK2
2% of total MB Heart 5
CK3
Slow moving MM Skeletal
muscle 80
Clinical significance of CK
• CPK & heart attack:
• CPK2 isoenzymes is very small, (2% of total CPK activity) &
undetectable in plasma.
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• In myocardial infarction (MI), CPK2 levels are increased within 4 hrs, then falls rapidly.
• Total CPK level is elevated upto 20-folds in MI.
CPK & Muscle diseases
• CPK level is elevated in muscular dystrophy (500-1500U/L)
• CPK level is highly elevated in crush injury, fracture & acute cerebrovascular accidents.
• Estimation of total CPK is employed in muscular dystrophies &
CPK-MB isoenzyme is estimated in myocardial infarction.
Atypical forms of CK Two atypical isoforms.
1. Macro-CK (CK-macro) Formation
• Formed by aggregation CK-MB with IgG, sometimes IgA.
• Also formed by complexing CK-MM with lipoproteins.
• Electrophoretically migrates between CK-MB & CK-MM.
• Occurs frequently in women above 50 years.
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CK-Mi (Mitochondrial CK-Isoenzyme) Formation
• It is present bound to the exterior surface of inner mitochondrial membrane of muscle, liver & brain.
• It exist in dimeric form & oligomeric aggregates & molecular weight 35,000
• Electrophoretically, migrates towards cathode & is behind CK- MM band.
• It is not present in normal serum.
Clinical significance
It is present in serum when there is extensive tissue damage causing breakdown of mitochondrial & cell wall. Its presence in serum indicates cellular damage, seen in malignancies.
Amylase
Amylase is a hydrolytic enzyme which hydrolyses starch into maltose/Glucose. Amylase is involved in the digestion of the polysaccharides of the diet. By definition alpha amylase are alpha 1, 4 – glucan – 4 – glucanohydrolase is an enzyme that splits starch randomly by breaking glucosidic bonds.
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Pancreatic salivary amylases are both alpha amylases, and beta amylases are of plant origin (alpha 1, 4 – glucan – maltohydrolase).
Malicular weight of amylase is 50,000 approximately and optimum PH is 6.9. For its optimum enzyme activity chloride is required.
Normal values for serum and urinary amylase varies according to laboratory and methods used. Normal values in serum is 60 to 160 Su / 100 ml and in urine is 35 to 260 Su / hr. One Su / 100 ml is equivalent to 1.85 Iu / L. On the basis of polyacrylamide gel electrophoresis, chromatography, isoelectric focusing serum and urinary amylase fractionated into two principal isoenzymes.
1. Pancreatic type (P – type isoamylase) 2. Salivary type (S – type isoamylase)
P - Type isoamylase in serum and urine derived from pancreas. S – Type amylase derived from not only from salivary gland and also from other organs. S - Type isoamylase seen predominantly in normal serum but P - Type isoamylase is predominantly seen in normal Urine. There is one more isoamylase a Third Type described as X – Type isoamylase.
P - Type isoamylase cleared 80% rapidly by kidneys than salivary isoamylase. Majority of serum amylase cleared by extra renal mechanism mainly by reticuloendothelial system. Urinary excretion is only about 24
%. This explains why normal are only mild increase of serum amylase in
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renal insufficiency. It is suggested that in patients with acute pancreatitis, it is advised to determined sequential 1- hour urinary amylase every 8 – 12 hours.
Hyperamylasemia seen in conditions like acute and chronic pancreatitis, pancreatic carcinoma and pancreatic trauma. Disorders of non pancreatic origin like renal insufficiency, salivary gland lesions like mumps calculus radiation surgery. It is elevated in some other conditions for which mechanism unknown are biliary tract disease, ruptured ectopic pregnancy peritonitis, acute appendicitis peptic ulcer perforation, cerebral trauma, burns DKA prostatic disease, pneumonia.
Materials and Methods
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4. MATERIALS AND METHODS
AIM OF STUDY
To assess the linear correlation between severity of OP poisoning in relation to respiratory system and levels of serum CPK and amylase levels and predicting Requirement of ventilatory support.
DESIGN OF STUDY
PROSPECTIVE STUDY PERIOD OF STUDY
6 MONTHS (MARCH 2019 – AUGUST 2019) STUDY POPULATION & MATERIAL
The study will be conducted on 100 patients admitted in Government Rajaji Hospital during the study period. 3 ml of blood will be collected from all study subjects before administration of Atropine, at time of admission and serum CPK and serum amylase will be estimated INCLUSION CRITERIA
Patients admitted with H/O organophophorus poisoning within previous 24 hours with cholinergic toxidromes in adult age group.
