Introduction:
Poisoning is the most common mode of unnatural death in South East Asia causing hundreds of thousand deaths per year. Among them Organophosphorus (OP) compound, a pesticide poisoning is the major clinical problem. Organophosphorus pesticide poisoning is a main clinical and public health problem across much of rural Asia [1]. Of the estimated 500,000 deaths from self-harm in the region each year, about 60% are due to pesticide poisoning. Many studies conclude that organophosphorus pesticides are responsible for around two-thirds of these deaths, a total of 200,000 a year [2]. The suicidal intent is the most common mode of poisoning whereas others are an impulsive act, homicidal, accidental and various other triggering factors.
In the developing world, poisoning is a common method of suicide[3] and a major health hazard [4]. Diagnosis is made on the basis of clinical suspicion, a smell of pesticides or solvents, the characteristic clinical signs and reduced butyrylcholinesterase or acetylcholinesterase activity in the blood.
Early diagnosis is a key to cure. As there is limited availability of facilities and resources in developing countries, all OP poisoning patients are not managed in intensive care units. Hence it is important to know the clinical features and other factors that indicate the severity of poisoning and criteria to speculate the need for ventilator support which should be identified in the initial examination. In our study we aim to assess the severity of organophosphorus compound poisoning both clinically by using Peradeniya scoring and by estimating serial serum cholinesterase levels in predicting prognosis, outcome and complications. Due to limited availability of facilities and resources in health care systems and economically restrain patients, it is necessary to rely more on clinical features to assess the severity of poisoning. The Peradeniya Organophosphorus Poisoning (POP) scale assesses the severity of the poisoning based on the symptoms at presentation and it is simple to use. In a study by Senanayake et al[5], patients with a high score on the POP scale had a high rate of morbidity and mortality. This study is thus an attempt to predict the severity in acute organophosphate poisoning with clinical scoring and serum pseudocholinesterase levels.
Material and Methods
The study was conducted at Department of Medicine, Indira Gandhi Medical College (IGMC) Shimla, which is a tertiary care centre of Himachal Pradesh. Patients admitted with history of organophosphorous poisoning during the period of 1/6/2018 to 30/7/2019. It was a hospital based prospective observational study carried over the patients presenting in Medicine Department IGMC Shimla with a history of organophosphorous exposure. Prior approval for the study was obtained from the Institutional Review Committee.
Immediately after the arrival of the patients at the emergency, history was taken to confirm the type of OP compound taken and the interval between the consumption of poison and arrival at the emergency room. Consent of the patient and /or guardian was taken. Apart from the detailed clinical examination, assessment was also done based on the POP scoring system, which included pupil size, respiratory rate, pulse rate, level of consciousness of the patient and the presence or absence of convulsions and fasciculations. Based on this assessment, a score was given to the patients. Information was collected through pre-tested proforma. Clinical score (POP scale) was noted on admission and accordingly patients were grouped into mild (POP score 0-3), moderate (POP score 4-7) and severe poisoning (POP score 8-11). When the patient was admitted in our hospital, after obtaining informed consent, about 5ml of blood was collected in plain tube under aseptic precautions. The blood sample was used for the analysis of following parameters.
- Serum pseudocholinesterase.
- Serum CPK.
- Serum Amylase.
 |
Table 1: Peradeniya Organophosphate Poisoning score[5] |
Blood samples were taken immediately and sent to lab attached to IGMC for estimation of above values before doing any intervention. According to cholinesterase activity (pseudocholinesterase level) the OP poisoning was graded as no poisoning (>50%), mild (20-50%), moderate (10-20%) and severe (<10%).Patients were evaluated at time of admission and were followed up during treatment up to death/discharge. The patients were routinely managed as per protocol in the wards or ICU according to the severity, with pralidoxime and intravenous (IV) atropine bolus and drip, maintaining the adequate level of atropinization. For clinical outcome, the total duration of hospital stay or death were considered. Complete recovery or death was used as the end point.
Inclusion criteria
A history of exposure to organophosphorus compound within previous 24 hours, with characteristic clinical manifestations of organophosphorus compound poison or physical evidence(container or photograph on smartphone) of the poison consumed.
Exclusion criteria
Patients with chronic medical conditions or diseases those are likely to alter the respiratory effort due to organophosphorous compound poisoning like bronchial asthma, cardiac diseases, and neuromuscular diseases like myasthenia gravis or muscular dystrophy. Patients who consumed other poisons along with organophosphorus compound, history of chronic liver or pancreatic disease, Pregnancy and History of concomitant alcohol consumption were also excluded.
Data was collected and entered in Microsoft excel spread sheet, cleaned for errors and analysed using EPI info version 7.2.1.0 software. Proportions and percentage was used to describe categorical variables. For continous variables data was normally distributed, mean and standard distribution was calculated and for non normal distribution, median and inter quartile range was calculated. The data was analysed using appropriate statistical test technique. Univariate correlation between these with the POP scale severity of poisoning and the serum cholinesterase level were evaluated using Pearson correlation coefficient, Chi Square test . A P value of less than 0.05 was considered to be significant.
Results
A total of 60 patients of organophosphorus poisoning who were admitted in medicine department in IGMC SHIMLA with history of organophosphorous poisoning were studied in this prospective observational study, based on the inclusion and exclusion criterion. Among them 68% were males and 32% were females. In this study there was male predominance, and male to female ratio was 2:1. The age of patients ranged from 18 to 68 years. Most of the patients were aged between 21 to 40 years and median age was 31.5 years. Patients consumed chlorpyrifos (71.67%), monocrotophos (3.33%), dichlorvos (15%), methyl parathion (1.67%), dimethoate (1.67%) in decreasing order of frequency. Most common poison consumed was chlorpyrifos (brand name Durmet) followed by dichlorovos.
| Table-2: Distribution of patients according to clinical features of OP poisoning |
Clinical features |
Percentage |
Bradycardia |
73 |
Miosis |
28 |
Altered Sensorium |
25 |
Tachypnea |
21 |
Fasciculation |
12 |
Seizure |
4 |
Several provoking factors responsible for poisoning are household conflict (75%), depressive illness (10%) and unknown in (15%). The mean lag time between poisoning and arrival to the emergency department was 8 hours. Salivation and vomiting were the most common symptoms. Around 73% of patient presented with bradycardia, as the most common sign, 28% of patients with miosis, 25% of patients with altered sensorium, 21% of patient with tachypnea, 12% of patients with fasciculation and 4% of patients with seizures (Table 2).
| Table-3: Serum Pseudocholinesterase level and mortality |
Level (IU/ml) |
Poisoning |
Total % (n=60) |
Males % (n=41) |
Females % (n=19) |
2160-5280 |
Mild |
63.33 (38) |
60.98 (25) |
68.42 (13) |
1080-2160 |
Moderate |
23.33 (14) |
24.39 (10) |
21.05 (4) |
540-1080 |
Severe |
13.33 (8) |
14.63 (6) |
10.53 (2) |
Most of the patients (83%) who recovered completely and discharged without ventilator support, had their serum pseudo cholinesterase level above 4000 U/L, POP score was below 4 and mean duration of hospital stay 5 days. 23% patients required ventilator support. Death occurred in 17% of patients. Categorisation as per cholinesterase levels revealed 38 (63%) patients in mild, 14 (23%) in moderate and 8 (13.33%) patients in severe poisoning category. One out of 14 patients and 8 out of 8 patients died in the moderate and severe poisoning categories respectively, suggestive of lower cholinesterase level being directly correlated to mortality, which was statistically significant. Eleven out of 14 patients in moderate poisoning and all patients in severe poisoning required ventilation (Table 3).
| Table-4: Severity according to POP score |
|
Total % (n=60) |
Male (n=41) |
Female (n=19) |
Mild poisoning (0-3) |
60 (36) |
58.54 (24) |
63.16 (12) |
Moderate poisoning (4-7) |
36.67 (22) |
36.59 (15) |
36.84 (7) |
Severe poisoning (8-11) |
3.33 (2) |
4.88 (2) |
0 |
There was significant correlation between the severity of poisoning categorized by the POP scale and the serum cholinesterase at the time of initial presentation of the patients (P<0.001), requirements of atropine on the first day of admission, the total amount of dose of atropine needed (P<0.001) and the average duration of hospital stay (P<0.001) (Figure 1). According to POP scale assessment, 36(60%) patients had mild poisoning while 22(36%) had moderate and 2 (3%) patient had severe poisoning (Table 4).
 |
Figure-1: Negative correlation was observed between the POP score and pseudocholinesterase level, with statistically significant r-value of-0.75091 |
| Table 5: POP score and need for ventilatory support |
POP score |
Ventilatory support |
|
|
|
Not Required |
Required |
Chi square |
P value |
Mild poisoning (0-3) |
36 |
0 |
24.22 |
0.0000 |
Moderate poisoning (4-7) |
10 |
12 |
16.26 |
0.0000 |
Severe poisoning (8-11) |
0 |
2 |
3.08 |
0.05 |
Duration of hospital stay was more in patient with POP score more than 4 and both severely poisoned patients died, while in moderate category 8 out of 22 patients died. When analysed statistically it was found to be statistically significant (<0.001) suggestive of more severe POP scale score more is mortality. Ten out of 22 patients in moderate poisoning and all patients in severe poisoning required ventilator support. Need of ventilation was more in people with high POP scale (Table 5).
Discussion
The most affected by organophosphorus poisoning are the males in the age group of 18-30 years as observed by the study conducted by Dayanand Raddi et al [6]. Being the most critical period when the person is likely to face many problems leading to psychological stress, vulnerable persons may take drastic steps to end the life by consuming toxic substances. The clinical and diagnostic findings of this study are compared with studies in the literature. In the current study, the household conflict was found as the most provoking factor for self-poisoning (75.4%) which was consistent with other studies[6-8]. Suicide being the main motive for poison consumption has been corroborated by Mood et al[7], who reported it to be at 94.3%. It was reported at 67% by Murat et al[8]. In the present study, majority of patients were in 21 to 40 years of age group. Most of the patients were from rural part of Himachal. This pattern of age group and demographic factors were reported in other studies also[9]. These insecticide agents are widely used in rural areas of Himachal especially for spraying in apple orchards and thus are easily available. This may be the reason for increased incidence of OP compounds for self harm purpose. Studies done in India and outside of our country where agriculture is a main occupation has highlighted this fact[8,9].
Zawar S D et al[10], Rehiman S et al[11] and Arup K K et al[12] showed that bradycardia, miosis, tachypnoea, diarrhoea, vomiting, altered sensorium and fasciculations are commonly present in OP poisoning patients, which is comparable to present study. In our study according to POP score 60% had mild, 37% with moderate and 3% had severe poisoning. The severity of the clinical features at presentation used in POP scale correlated well with need for ventilator support. Present study showed significant correlation between the degree of derangement in serum pseudo cholinesterase level and severity of poisoning at the initial presentation. The higher the score on the POP scale, the higher was the degree of derangement in the serum pseudo cholinesterase level. There was significant correlation between POP score, serum pseudo cholinesterase and in hospital outcome. The chances of developing respiratory failure and requiring ventilator support is highest in the severe group, which in case of our study showed all subjects in this group progressing to respiratory failure. This indicates the importance of POP score as a tool for early predictor of respiratory failure. These findings are consistent with studies done by Rehiman et al[11], Zawar S D et al[10], Jha S et al[13], Goel et al[14], Sam KG et al[15] and Aygun et al[16]. Another outcome which was noted to be seen in all the patients in the severe group in our study was longer duration of respiratory failure requiring prolonged ICU stay (> 7days) suggesting a higher incidence of intermediate syndrome in this group. Study by Subhash et al[17] showed need for ventilator support in 62.5% of patients with moderate poisoning and 100% of patients with severe poisoning according to POP scale. Similarly in present study patients with moderate and severe grades of poisoning according to POP score were managed with ventilator support. Respiratory failure was common feature in severe grade of poisoning, which is primarily due to respiratory paralysis due to nicotinic effect and increased work load on respiratory muscles due to muscarinic effect.
In our study, there was significant difference in serum cholinesterase activity between mechanically ventilated patients and those who did not require mechanical ventilation and thus revealed that cholinesterase level on admission may be a reliable indicator for the selection of treatment modality. Also, there was significant difference in cholinesterase level between survivors and non-survivors.
In present study 17% of patients had died which is comparable to other similar studies[11,12,17]. Delay in hospitalization, higher clinical score at presentation accounted for mortality. The current study observed significant negative correlation of POP score and Pseudo cholinesterase level, with an r-value of -0.75091. This is suggestive of more severe POP scale with lower Pseudocholinesterase level. Death is usually a result of respiratory paralysis. The other complications which can lead to fatality are asphyxia as a result of increased bronchial secretions and bronchoconstriction and rarely pulmonary edema. Occasionally serious cardiac arrhythmias can lead to fatality. It is important to assess clinically at the time of initial presentation of OP poisoning to decide the level of care and to decrease the mortality and morbidity. Organophosphorus compound poisoning is seen in the productive population of males under the age of 40 years, hence there is an urgent need to get control of the situation. But this remains an uphill task which can be done with political commitment and regulation of sales of organophosphorus compounds. The Peradeniya score (POP) applied at admission was able to predict the outcome of the subjects in terms of morbidity. In this regard Peradeniya Organophosphorus Poisoning scale can be applied as a relatively easy and quick method to categorise the patients with OP poison on admission and also a reasonably reliable method to assess the outcome.
Conclusion
Organophosphorus is the most commonly used self-poisoning compound. We conclude that s POP score scale is useful for determining the severity of the poisoning. Also measuring serum cholinesterase level at the time of admission and serial monitoring during treatment would be considered as prognostic and predictive value for future reference. The higher the POP scale, the higher was the degree of derangement in the serum cholinesterase level. The facility of estimation of serum cholinesterase is not available in all centres of India. In that case, POP scale can be used to describe the severity of OP poisoning. POP scale can be used to treat OP poisoning patients in terms of need of ventilator, hospital stay and atropine dose; at the same time being important indicator of mortality. POP scale can be used readily in all level of health care from primary to tertiary level health care.
Limitations
This was a single hospital-based study with the relatively smaller sample size. Thus, a prospective and controlled study including a larger sample is needed. The study also did not include serial monitoring of Serum Pseudo cholinesterase level during hospital treatment which may provide a guide for the physicians in the evaluation and management of patients with OP poisoning.
Conflict of Interest: None.
References
- Eddleston M, Phillips MR. Self poisoning with pesticides. BMJ. 2004;328:42.
- WHO. The world health report 2002: reducing risks, promoting healthy life. World Health Organization. 2002.
- Vijayakumar L. Suicide prevention: the urgent need in developing countries. World psychiatry. 2004;3(3):158-9.
- Jeyaratnam J. Acute pesticide poisoning: a major global health problem. World Health Stat Q. 1990;43(3):139-44.
- Senanayake N, De Silva HJ, Karalliedde L. A scale to assess the severity of organophosphorus intoxication: POP scale. Hum Exp Toxicol 1993;12:297.
- Dayanand Raddi, Anikethana GV. Clinical profile of organophosphorus poisoning in a tertiary care hospital. Indian Journal of Basic and Applied Medical Research. 2014 Dec;4(1):14-22.
- Balali-Mood M, Balali-Mood K, Hosseini Shirazi F. Recent advances in treatment of acute organophosphorous nerve agents poisoning. Iranian J Pharmaceutical Research. 2010 Nov; 20:79-87.
- Murat S, Muhammed G. Intensive care management of organophosphate insecticide poisoning. Crit Care. 2001;5:211-5.
- Jesslin J, Adepu R, Churi S. Assessment of prevalence and mortality incidences due to poisoning in a South Indian tertiary care teaching hospital. Indian J Pharm Sci. 2010;72:587 91
- Zawar SD et al. Correlation between plasma cholinesterase levels and clinical severity of acute organophosphate and carbamate poisoning. JAPI 2001;149;91.
- Rehiman S, Lohani SP, Bhattarai MP. Correlation of serum cholinesterase level, clinical score at presentation and severity of OP poisoning. J Nepal Med Assoc 2008;47:47-52.
- Arup KK et al. Predictors of mortality in Organophosphorus Poisoning – Hospital based study from suburban West Bengal. JAPI 2011;49:91.
- Jha S, Chandra M, Sondhi D. OP poisoning and interpretationof its clinical study and management. Ind Med Gazette 1989;123:108-10.
- Goel A, Joseph S, Dutta TK. OP poisoning: predicting the needfor ventilatory support. J Assoc Phy India. 1998;46:786–9.
- Sam KG, Kondabolu K, Pati D, Kamath A, Pradeep Kumar G, Rao PG. Poisoning severity score, APACHE II and GCS: Effective clinical indices for estimating severity and predicting outcome of acute organophosphorus and carbamate poisoning. J Forensic Leg Med 2009;16:239-47.
- Aygun D, Doganay Z, Altintop L, Guven H, Onar M, Deniz T, et al. Serum acetylcholinesterase and prognosis of acute organophosphate poisoning. J Toxicol Clin Toxicol 2002;40:903-10.
- Patil SL, Vasepalli P. Prognostic value of clinical and lab parameters in assessing the severity of organophosphorous compound poisoning. Indian Journal of Basic and Applied Medical Research 2014;4:77-91.
|
