POP Scale (Organophosphate Poisoning Severity)
The Peradeniya Organophosphorus Poisoning (POP) scale (Senanayake and colleagues 1993), which grades the severity of acute organophosphate poisoning.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Pupil size
- Pinpoint
- Respiratory rate
- 20 or more per minute
- Heart rate
- 50 per minute
- Whether fasciculation is GENERALIZED
- Yes
- Whether fasciculation is CONTINUOUS
- No
- Level of consciousness
- Impaired response to verbal command
- Seizures
- Absent
Result: POP scale 6 of 11
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Maximum
- 11, NOT 12: five parameters score 0-2 but seizures scores 0-1 only.
- Pupil
- 2mm or more = 0; under 2mm = 1; pinpoint = 2. PINPOINT TAKES PRECEDENCE (the levels overlap).
- Respiratory
- Under 20 = 0; 20 or more = 1; 20 or more WITH central cyanosis = 2.
- Heart rate
- Above 60 = 0; 41-60 = 1; below 40 = 2. The interval 40 to under 41 is UNSCOREABLE.
- Fasciculation
- Generalized OR continuous = 1; BOTH = 2. A conjunction, not a severity ladder.
- Consciousness
- Rational = 0; impaired response = 1; no response = 2.
- 0 to 3
- Mild poisoning.
- 4 to 7
- Moderate poisoning.
- 8 to 11
- Severe poisoning.
- Timing
- Apply BEFORE treatment: atropine reverses miosis and bradycardia, two of the six parameters.
- Scope
- NOT a dosing instrument. Atropine is titrated to secretions and oxygenation, not to a score.
What you enter
- Pupil size.
- Respiratory rate
- Heart rate.
- Whether fasciculation is GENERALIZED.
- Whether fasciculation is CONTINUOUS.
- Level of consciousness
- Seizures.
Full field descriptions
- Pupil size. PINPOINT TAKES PRECEDENCE over "under 2 mm", which the published levels overlap [at-least-2mm = 2 mm or more, 0 points; under-2mm = Under 2 mm, but not pinpoint, 1 points; pinpoint = Pinpoint, 2 points]
- Respiratory rate [under-20 = Under 20 per minute, 0 points; at-least-20 = 20 or more per minute, 1 points; at-least-20-cyanosis = 20 or more per minute with central cyanosis, 2 points]
- Heart rate. Above 60 = 0; 41 to 60 = 1; below 40 = 2. EXACTLY 40 falls in NO published level and is REFUSED.
- Whether fasciculation is GENERALIZED. Combined with the continuous attribute as a conjunction: either alone scores 1, both score 2.
- Whether fasciculation is CONTINUOUS. Combined with the generalized attribute as a conjunction: either alone scores 1, both score 2.
- Level of consciousness [conscious = Conscious and rational, 0 points; impaired = Impaired response to verbal command, 1 points; none = No response to verbal command, 2 points]
- Seizures. HALF WEIGHT: 0 or 1 only, which is why the maximum is 11 and not 12 [absent = 0 points; present = 1 points]
How this is calculated
Senanayake N, de Silva HJ, Karalliedde L. A scale to assess severity in organophosphorus intoxication: POP scale. Hum Exp Toxicol. 1993;12(4):297-299. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.