Quantitative Assessment of Pupillary Light Reflex in Acute Carbon Monoxide Poisoning

Quantitative Assessment of Pupillary Light Reflex for the Prediction of Neurocognitive Outcomes of Acute Carbon Monoxide Poisoning: A Prospective Observational Study

Neurological complications after acute carbon monoxide (CO) poisoning can range from transient headache or dizziness to cognitive dysfunction, seizure, permanent anoxic brain damages or death. A recent study reported that a lack of standard pupillary light reflex (sPLR), assessed using a pen light, was a predictor of 30-day neurological sequelae in patients with CO poisoning. Given that the basic sPLR has a poor inter-rater reliability, more objective and quantitative methods are required in the assessment of PLR.

An automated pupillometer has been used in the intensive care unit to quantitatively assess the PLR. Therefore, we hypothesized that quantitative assessment of PLR might be associated with neurocognitive sequelae after acute CO poisoning. The purpose of this study was to assess the value of quantitative pupillary reactivity (NPi and qPLR) in comparison to that of sPLR in predicting neurocognitive outcome at 1 month after acute CO poisoning.

Study Overview

• Status: Completed
• Conditions: Carbon Monoxide Poisoning
• Intervention / Treatment: Diagnostic test: Automated quantitative pupillometer

Detailed Description

Neurological complications after acute carbon monoxide (CO) poisoning can range from transient headache or dizziness to cognitive dysfunction, seizure, permanent anoxic brain damages or death. Although hyperbaric oxygen therapy (HBO2) has been tried to minimize the neurological complications, a significant percentage of patients still suffer from neurocognitive sequelae after acute CO poisoning. A recent study reported that a lack of standard pupillary light reflex (sPLR), assessed using a pen light, was a predictor of 30-day neurological sequelae in patients with CO poisoning. Given that the basic sPLR has a poor inter-rater reliability, more objective and quantitative methods are required in the assessment of PLR.

An automated pupillometer has been used in the intensive care unit to quantitatively assess the PLR. Quantitative PLR (qPLR), which is expressed as the percentage pupillary constriction in response to a calibrated light stimulus, was better in predicting neurological outcome after cardiac arrest (CA) compared to standard light reflex. In addition, the Neurological Pupil index (NPi) has been validated as a tool for assessing prognosis after CA because it is not influenced by medications (especially opioids and neuromuscular blocking agents) or small pupil size.

Therefore, the investigators hypothesized that quantitative assessment of PLR might be associated with neurocognitive sequelae after acute CO poisoning. The purpose of this study was to assess the value of quantitative pupillary reactivity (NPi and qPLR) in comparison to that of sPLR in predicting neurocognitive outcome at 1 month after acute CO poisoning.

• Study Type: Observational
• Enrollment (Actual): 104

Contacts and Locations

Study Locations

• Korea, Republic of
  • Gangwon
    • Wonju, Gangwon, Korea, Republic of, 26426
      • Wonju Severance Christian Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 19 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Acute CO poisoning

Description

Inclusion Criteria:

• Acute CO poisoning

Exclusion Criteria:

• Age <19 years
• Patients with a history of ophthalmic surgery which might have affected the PLR
• Patients with baseline cognitive deficit
• Refusal to enroll in this study
• Discharge from the ED or transfer to another hospital within 24 hours
• Expired in the ED
• Co-ingestion of drugs, such as hypnotics, that may affect the PLR
• No follow-up for the neurocognitive outcome

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Acute CO poisoning; A diagnosis of CO poisoning was made according to medical history and carboxyhaemoglobin >5% (>10% in smokers).

Diagnostic test: Automated quantitative pupillometer; Quantitative measurement of pupillary variables was performed at the time of arrival at the ED (0 h), and at the 6-, 12-, and 24-h time points on hospital day (HD) 1. The worst value among those recorded within 24 h and during the total measurement period was selected as the 24-h and total lowest values. If a patient was discharged before HD 3, measurements were taken only until discharge. The initial value was measured within 1 h after arrival at the ED because of the requisite time for obtaining informed consent before enrollment. At each time point, the lowest values for the NPi and qPLR of each eye were retained for analysis. The sPLR (standard PLR) was serially measured in the ED and after admission by emergency physicians using a manual penlight. We classified the reactivity of the sPLR as reactive, sluggish, or non-reactive. Non-reactive sPLR was defined when pupillary reactivity was not identified bilaterally.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The prediction of neurological pupil index (NPi) for poor neurocognitive outcome	The predictive value of NPi for the 1-month poor neurocognitive outcome after acute CO poisoning	Within 3 days after acute CO poisoning
The prediction of quantitative pupillary light reflex (qPLR) for poor neurocognitive outcome	The predictive value of qPLR for the 1-month poor neurocognitive outcome after acute CO poisoning	Within 3 days after acute CO poisoning
Comparison of predictive value for poor neurocognitive outcome between NPi and standard pupillary light reflex (sPLR)	The value of NPi in comparison to that of sPLR in predicting neurocognitive outcome at 1 month after acute CO poisoning	Within 3 days after acute CO poisoning
Comparison of predictive value for poor neurocognitive outcome between qPLR and sPLR	The value of qPLR in comparison to that of sPLR in predicting neurocognitive outcome at 1 month after acute CO poisoning	Within 3 days after acute CO poisoning

Collaborators and Investigators

• Sponsor: Wonju Severance Christian Hospital
• Collaborators: Seoul National University Bundang Hospital

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2019
• Primary Completion (Actual): December 31, 2020
• Study Completion (Actual): January 31, 2021

Study Registration Dates

• First Submitted: October 14, 2021
• First Submitted That Met QC Criteria: October 26, 2021
• First Posted (Actual): November 8, 2021

Study Record Updates

• Last Update Posted (Actual): November 8, 2021
• Last Update Submitted That Met QC Criteria: October 26, 2021
• Last Verified: October 1, 2021

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Chemically-Induced Disorders; Gas Poisoning; Poisoning; Carbon Monoxide Poisoning
• Other Study ID Numbers: CO-pupillometer

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No