Analysis of long-term prognosis of neurological sequelae in children with carbon monoxide poisoning
Authors: Wen Tuoying , Liang Jinghong , Wei Yulan , Lin Weijun , Pan Liya 
Published: April 2024

Background
Carbon monoxide poisoning is a common gas poisoning in emergency rooms during winter, but there are very few reports on carbon monoxide poisoning in children and long-term follow-ups. Epidemiological studies have shown that in China, infants (0-4 years old) and elderly people (70 years old and above) have a higher risk of DALYs (disability-adjusted life years), while young people (15-24 years old) have a higher risk of CO poisoning1. For carbon monoxide poisoning in children, long-term cognitive impairment, if it occurs, will have a detrimental effect on children's neurodevelopment and long-term healthy growth.
Method:
This study retrospectively analyzed children admitted to the Fourth Affiliated Hospital of Guangxi Medical University for carbon monoxide poisoning from January 2018 to December 2022, and followed up on their neurological sequelae for a long period of time. The study was approved by the Ethics Committees of the Fourth Affiliated Hospital of Guangxi Medical University (the identification code was KY2023131) and informed consent was obtained from all participants and/or their legal guardians. The study complied with the Declaration of Helsinki. Through GDS scores, we further compared the differences between children with and without cognitive impairment，and identified some risk factors for long-term cognitive impairment in children after carbon monoxide poisoning.
Result
A total of 113 children were included in the study, with an average follow-up of 3.6 years (3.6±1.5 years). Among them, 13 children (11.5%, 13/113) had cognitive abnormalities. The use of gas water heaters in enclosed bathrooms (101 cases, 89.4%) was the most common cause of poisoning in children in this study, followed by heating with fire (11 cases, 9.7%). In addition, one child was forgotten by his father in a running car, resulting in poisoning. The clinical manifestations of children with cognitive abnormalities were mainly consciousness disorders (67 cases, 59.3%), dizziness or headache (37 cases, 32.7%), and other manifestations including irritability, crying, vomiting, limb weakness, and limb twitching, a total of 9 cases. The duration of consciousness disorders in children with cognitive abnormalities was mostly more than 1 day, with a median of 5 days, and the hospitalization time was longer. Children with cognitive abnormalities had higher CRP levels, higher D-dimer levels, and higher liver enzyme levels. The most common imaging change after carbon monoxide poisoning in children was cerebral edema, with two cases of subarachnoid hemorrhage observed and one case of demyelinating changes observed. For children with coma time less than 1 hour, there were few abnormal changes in cranial imaging. Children with cognitive abnormalities were more likely to develop epilepsy (38.5%, 5/13) and other system damage (53.8%, 7/13) during hospitalization, including pulmonary infection (3 cases), stressful gastrointestinal bleeding (2 cases), electrolyte imbalance (2 cases), liver and kidney or myocardial dysfunction (3 cases), and some children had multiple system damage at the same time.
There were statistical differences in the admission carbon monoxide hemoglobin level, fibrinogen, D-dimer, high-sensitivity C-reactive protein, neuron enolase, ALT/AST, lactate dehydrogenase, length of hospital stay, discharge and admission GCS scores, seizure frequency, duration of consciousness disorders exceeding 1 day, cranial imaging changes, use of ventilators, presence of other system damage, number of HBOT treatments, and whether the patient was transferred to another hospital between the two groups of children. Multivariate logistic regression analysis showed that the need to transfer to a higher-level hospital for treatment due to the severity of the condition and longer duration of coma were independent risk factors for cognitive impairment after long-term follow-up.
Conclusion
For children with an unconsciousness of more than 1 hour, it is recommended to consider performing a head imaging examination as soon as possible within 3 days after CO exposure to guide the treatment of the acute phase. For children who are transferred from lower-level hospitals to higher-level hospitals for treatment after poisoning, with an unconsciousness of more than 1 day or 5 days and more, long-term follow-up should be conducted to determine whether delayed encephalopathy or long-term cognitive impairment occurs, and timely and long-term intervention measures should be formulated.