Prognostic factors of carbon monoxide poisoning in Taiwan: a retrospective observational study

Correlation between Time to Hyperbaric Oxygen Therapy and Delayed Neurological Sequelae in Acute Carbon Monoxide Poisoning Patients

Carbon monoxide (CO) is one of the most common causes of intoxication. Delayed neurologic sequelae (DNS) have a major impact on prognosis of CO poisoning patients. Hyperbaric oxygen therapy (HBOT) is widely used to treat DNS. However, there is no consensus regarding the optimal timing of HBOT. This prospective study enrolled patients who visited the hospital from November 2019 to October 2022. The cutoff value for the latency to HBOT after CO exposure was determined, and the area under the receiver operating characteristic curve (AUC) was estimated. In total, 167 patients were divided into non-DNS and DNS groups. The initial Glasgow Coma Scale (GCS) score, CO exposure time, latency to HBOT after CO exposure, median length of hospital stay (p < 0.001) and creatine kinase (p = 0.016) showed significant differences. A GCS score ≤ 9 had an odds ratio (OR) of 5.059 (95% confidence interval [CI]: 1.602-15.976, p = 0.006), and latency to HBOT after CO exposure ≥ 200 min had an OR of 18.971 (95% CI: 4.310-83.508, p < 0.001). The AUC was 0.8235 (95% CI: 0.7504-0.8966). A GCS score ≤ 9 and latency to HBOT ≥ 200 min may be significant risk factors for DNS.

Quantitative pupillary light reflex assessment for prognosis of carbon monoxide poisoning

Background

A non-reactive pupil in standard pupillary light reflex (sPLR) is regarded as a factor predicting neurological sequelae at 1-month after carbon monoxide (CO) poisoning. An automated pupillometer is used in the intensive care unit to quantitatively assess PLR. Quantitative PLR (qPLR) was superior to sPLR using penlight for prognosis of various neurological diseases. Therefore, this study aimed to analyze whether quantitative pupillary variables (neurological Pupil index [NPi] and qPLR) are superior to sPLR in predicting 1-month neurocognitive sequelae after acute CO poisoning.

Methods

We performed a prospective observational study of consecutive patients with acute CO poisoning admitted to an emergency department (ED) between August 2019 and December 2020 in a single academic medical center. sPLR and pupillometer examinations (qPLR and NPi) were performed by emergency physicians at the ED on hospital days 0-2. The lowest values among those recorded within 24 h and during the total measurement period were considered the 24-h and total lowest values, respectively. Global Deterioration Scale scores were measured at 1 month as an outcome and were dichotomized into favorable (1-4) or poor (5-7) outcomes.

Results

We analyzed the data of 104 adult patients with acute CO poisoning. qPLR was significantly higher in the favorable outcome group than in the poor outcome group 24-h and total lowest values (21.2% vs. 15.0%, p = 0.006 and 21.0% vs. 14.8%, p = 0.006). qPLR <18% had fair predictive power for poor neurocognitive outcomes [area under the curve (AUC), 0.70; 95% confidence interval (0.60-0.78)]. Among the patients with decreased mental status (Glasgow Coma Scale ≤12), the power of NPi and qPLR increased [AUC, 0.72 and AUC, 0.80]. NPi < 1 and qPLR <18% showed sensitivity (9.5% vs. 76.2%) and specificity (98.8% vs. 67.5%) for the prediction of poor outcomes. qPLR was significantly superior to sPLR in predicting poor neurocognitive outcomes at 1 month after CO poisoning (p = 0.007).

Conclusion

qPLR and NPi were superior to sPLR in terms of predicting poor neurocognitive outcomes. qPLR and NPi measured from hospital days 0-2 may be valuable in predicting neurocognitive outcome.

Validation of Diagnostic Codes to Identify Carbon Monoxide Poisoning in Taiwan’s Claims Data

Purpose: Previous studies identified the study cohort or outcome of carbon monoxide poisoning (COP) by using the relevant disease diagnosis codes in secondary databases, but the validity of diagnosis codes of COP is unclear in such secondary databases. This study aimed to evaluate the accuracy of case definitions for COP using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes in Taiwan’s health insurance claims data.

Methods: We selected a 10% simple random sample from an original cohort of patients newly undergoing carboxyhemoglobin (COHb) testing under any clinical diagnosis at four Chang Gung Memorial Hospitals in Taiwan during 2011–2020. Two clinical doctors independently ascertained the COP diagnosis by reviewing the medical records as the reference standard. We estimated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various case definitions (e.g., ICD-9-CM code, ICD-10-CM code and the uses of hyperbaric oxygen therapy) in the claims data.

Results: We randomly selected 557 cases from the original cohort of 5,571 cases newly receiving COHb test in the study hospitals. We found 90, 35, and 9 cases were true-positive, false-positive, and false-negative episodes of COP, respectively, among 278 cases with an ICD-9-CM code of 986. A further 111, 34, and 6 cases were true-positive, false-positive, and false-negative episodes of COP, respectively, among 279 cases with an ICD-10-CM code of T58. Using ICD-9-CM codes, the sensitivity, specificity, PPV and NPV for COP were 90.9, 80.4, 72, and 94.1%, respectively. Using ICD-10-CM codes they were 94.9, 79, 76.6, and 95.5%, respectively. PPV typically increased when COP was the primary diagnosis and could reach 100% if patients with ICD-CM code 986 or T58 also received hyperbaric oxygen therapy during hospitalization.

Conclusion: The COP-related ICD-CM codes alone did not accurately identify COP patients, but accuracy improved after including oxygen therapy data with the ICD-CM codes in Taiwan’s claims data.

Derivation and Validation of a Score for Predicting Poor Neurocognitive Outcomes in Acute Carbon Monoxide Poisoning

IMPORTANCE

Preventing neurocognitive sequelae is a major goal of treating acute carbon monoxide (co) poisoning. There is a lack of reliable score systems exist for assessing the probability of these sequelae.

OBJECTIVE

To develop and validate a novel clinical scoring system for predicting poor neurocognitive outcomes after acute co poisoning.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study included derivation and validation cohorts based on consecutive patient data prospectively collected at university hospitals from January 2006 to July 2021 in Wonju, Republic of Korea, and from August 2016 to June 2020 in Incheon, Republic of Korea. Participants included individuals aged 16 years or older admitted with co poisoning. Data were analyzed from October 2021 to January 2022.

EXPOSURES

Clinical and laboratory variables.

MAIN OUTCOMES AND MEASURES

The outcome of interest was neurocognitive sequelae at 4 weeks after co poisoning. Logistic regression models were used to identify predictors of poor neurocognitive outcomes in the derivation cohort. Outcomes were assessed using the Global Deterioration Scale [GDS] at 1-month after co exposure and classified as good (1-3 points) or poor (4-7 points).

RESULTS

A total of 1282 patients (median [IQR] age, 47.0 [35.0-59.0] years; 810 [63.2%] men) were assessed, including 1016 patients in the derivation cohort and 266 patients in the validation cohort. The derivation cohort included 126 patients (12.4%) with poor GDS scores. Among 879 patients in the derivation cohort with 1-year follow-up data, 757 (86.1%) had unchanged GDS scores, 102 (11.6%) had improved GDS scores, and 20 (2.3%) had worsened GDS scores. In the final prediction model, age older than 50 years (1 point), Glasgow Coma Scale score of 12 or less (1 point), shock (1 point), serum creatine kinase level greater than 320 U/L at emergency department presentation (1 point), and no use of hyperbaric oxygen therapy (1 point) remained factors significantly associated with worse outcome; therefore, this scoring system was called COGAS (creatine kinase, hyperbaric oxygen therapy, Glasgow Coma Scale, age, shock). Area under the receiver operating characteristic curve for COGAS score was 0.862 (95% CI, 0.828-0.895) for the derivation cohort and 0.870 (95% CI, 0.779-0.961) for the validation cohort.

CONCLUSIONS AND RELEVANCE

These findings suggest that assessing the COGAS score during the early phase of co poisoning may help identify patients at risk of poor neurocognitive sequelae.

Effects of smoking on delayed neuropsychiatric sequelae in acute carbon monoxide poisoning: A prospective observational study

Smoking is a well-known risk factor for cardio-cerebrovascular disease. However, several studies have reported the "smoker's paradox" whereby smokers have a better prognosis for cardio-cerebrovascular diseases. Similar to cardio-cerebrovascular diseases, hypoxia is one of the major mechanisms of injury in carbon monoxide (CO) poisoning. This study investigated the association between smoking and delayed neuropsychiatric sequelae (DNS) in acute CO poisoning.This study involved patients with CO poisoning treated at a university hospital in Bucheon, Korea between September 2017 and March 2020. The exclusion criteria were age <18 years, discharge against medical advice, loss to follow-up, persistent neurological symptoms at discharge, transfer from another hospital 24 hours after exposure, and transfer from another hospital after hyperbaric oxygen therapy. Logistic regression analysis was performed to find factors associated with DNS.Two hundred sixty three patients visited the hospital due to CO poisoning and of these, 54 were excluded. DNS was evaluated up to 3 months after discharge, and until this time, DNS occurred in 35 (16.8%) patients. And the incidence rate of DNS was lower in smokers than non-smokers (15, 12% vs 20, 23.8%, P = .040). Multivariable logistic regression analysis revealed that CO exposure time (odds ratio [OR] 1.003; confidence interval [CI] 1.001-1.005; P = .003), the Glasgow coma scale (GCS) (OR 0.862; CI 0.778-0.956; P = .005), and pack-years (OR 0.947; CI 0.903-0.993; P = .023) were statistically significant for DNS development.These results indicate that more pack-years smoked were associated with reduced risk of the development of DNS in acute CO poisoning, and that CO exposure time and GCS is a predictive factor for DNS occurrence.

Carbon Monoxide Poisoning and Chronic Kidney Disease Risk: A Nationwide, Population-Based Study

INTRODUCTION

Patients with carbon monoxide poisoning (COP) commonly have long-term morbidities. However, it is not known whether patients with COP exhibit an increased risk of developing chronic kidney disease (CKD) and whether hyperbaric oxygen therapy (HBOT) alters this risk.

METHODS

This study identified 8,618 patients who survived COP and 34,464 propensity score-matched non-COP patients from 2000 to 2013 in a nationwide administrative registry. The primary outcome was the development of CKD. The association between COP and the risk of developing CKD was estimated using a Cox proportional hazards regression model; the cumulated incidence of CKD among patients stratified by HBOT was evaluated using a Kaplan-Meier analysis.

RESULTS

After adjusting for covariates, the risk of CKD was 6.15-fold higher in COP patients than in non-COP controls. Based on the subgroup analyses, regardless of demographic characteristics, environmental factors, and comorbidities, the COP cohort exhibited an increased risk of developing CKD compared with the controls. The cumulative incidence of CKD in COP patients did not differ between the HBOT and non-HBOT groups (p = 0.188).

CONCLUSIONS

COP might be an independent risk factor for developing CKD. Thus, clinicians should enhance the postdischarge follow-up of kidney function among COP patients.

Clinical predictors of delayed neurological sequelae in charcoal-burning carbon monoxide poisoning

BACKGROUND

The main objective of the treatment of acute carbon monoxide (CO) poisoning is to prevent delayed neurological sequelae (DNS). However, today there is still no objective screening tool to identify patients at high risk of developing DNS. The aim of this study was to identify clinical factors that could predict DNS after acute charcoal-burning CO poisoning.

METHODS

This prospective observational study was conducted from September 1, 2019 to August 31, 2020 in a single academic medical center. Patients older than 18 years of age suffering from charcoal-burning CO poisoning were included in the study. After acute recovery, patients were followed up for six weeks to investigate for DNS development. The clinical predictors of DNS were determined using a multivariate logistic regression model.

RESULTS

Of the 217 patients-113 males (52.1%), median age 37.0 (27.5-51.5) years-included, 49 (22.6%) developed DNS. The multivariate logistic regression analysis revealed the independent predictors of DNS as a lower initial Glasgow Coma Scale (GCS) score (adjusted odds ratio (AOR): 0.73, 95% confidence interval (CI): 0.62-0.87), a longer duration of CO exposure (AOR: 2.18, 95% CI: 1.65-2.88), and the presence of acute brain lesions with high signal intensity on diffusion-weighted imaging (AOR: 5.22, 95% CI: 1.50-18.08). The created multivariate regression model predicted DNS development with high accuracy (area under the curve: 0.93, 95% CI: 0.89-0.97).

CONCLUSION

A low initial GCS score, longer exposure to CO and abnormal findings on diffusion-weighted magnetic resonance imaging can assist in the early identification of patients at high risk of DNS development.

The risk factors for delayed recovery in patients with cardiopulmonary bypass: Why should we care?

Cardiopulmonary bypass (CPB) is very commonly performed among the cardiovascular surgeries, and delayed recovery (DR) is a kind of serious complications in patients with CPB. It is necessary to assess the risk factors for DR in patients with CPB, to provide evidence into the management of CPB patients.Patients undergoing CPB in our hospital from January 2018 to March 2020 were included. Cases that consciousness has not recovered 12 hours after anesthesia were considered as DR. The preoperative and intraoperative variables of CPB patients were collected and analyzed. Logistic regressions were conducted to analyze the potential influencing factor.A total of 756 CPB patients were included, and the incidence of DR was 9.79%. There were significant differences on the age, aspartate aminotransferase (AST), glutamic pvruvic transaminase (ALT), blood urea nitrogen (BUN), and serum creatinine (SCr) between patients with and without DR (all P < .05); there were no significant differences in the types of surgical procedure (all P > .05); there were significant differences on the duration of CPB, duration of aortic cross clamp (ACC), duration of surgery, minimum nasopharyngeal temperature, and transfusion of packed red blood cells between patients with and without DR (all P < .05). Logistic regression analysis indicated that duration of CPB ≥132 minutes (odds ratio [OR] 4.12, 1.02-8.33), BUN ≥9 mmol/L (OR 4.05, 1.37-8.41), infusion of red blood cell suspension (OR 3.93, 1.25-7.63), duration of surgery ≥350 minutes (OR 3.17, 1.24-5.20), age ≥6 (OR 3.01, 1.38-6.84) were the independent risk factors for DR in patients with CPB (all P < .05).Extra attention and care are needed for those CPB patients with duration of CPB ≥132 minutes, BUN ≥9 mmol/L, infusion of red blood cell suspension, duration of surgery ≥350 minutes, and age ≥60.

Prognosis of patients in prolonged coma after severe carbon monoxide poisoning

BACKGROUND

Late recovery in patients following prolonged coma from carbon monoxide poisoning have been reported, but the probability is unclear. The purpose of this research was to assess the prognosis of patients in prolonged coma after severe carbon monoxide poisoning and related clinical and imaging features.

METHODS

There were 13 patients who had been in a state of coma for >7 days after acute carbon monoxide poisoning in the retrospective observational study, and demographic data, clinical data, laboratory data, complications, and image data were collected. Outcome was assessed by means of the Glasgow outcome scale after 1 year. The relationship between complications and imaging manifestations and prognosis was also analyzed.

RESULTS

One year after severe carbon monoxide poisoning, two patients (15.4%) had died (GOS 1), nine (69.2%) were in a persistent vegetative state (GOS 2), one (7.7%) was moderately disabled (GOS 4), and one (7.7%) achieved a good recovery (GOS 5) with minimal disability.

CONCLUSIONS

Most patients with prolonged coma after severe carbon monoxide poisoning had a poor prognosis, although the younger patients had a better prognosis. Respiratory failure, hypotension and renal failure during the course of the disease were associated with a poor prognosis. The prognosis of patients with injuries in two sites in early CT was poor. Multiple lesions (≥3) and extensive white matter damage (Fazekas grade (PVH or DWMH) = 3) on MRI of chronic phase were also associated with a poor prognosis.

Cox regression model of prognostic factors for delayed neuropsychiatric sequelae in patients with acute carbon monoxide poisoning: A prospective observational study

OBJECTIVE

A major challenge for physicians is to identify patients with acute carbon monoxide (CO) poisoning who are likely to develop delayed neuropsychiatric sequelae (DNS). DNS is defined as neuropsychological sequelae that develops after 2-40 days of lucid interval after CO intoxication. Currently, there is no consensus on factors that predict the prognosis of CO poisoning. Thus, the purpose of this study was to identify factors predicting the development of DNS using a Cox regression model.

METHODS

This prospective observational study included 310 CO-poisoned patients admitted to an emergency department in South Korea from July 2017 to February 2020. Demographic, clinical, and laboratory data were analyzed. Kaplan-Meier curves were constructed to estimate the cumulative incidence of DNS. A multivariate Cox regression model was used to identify the main predictors of the development of DNS.

RESULTS

The incidence of DNS was 18.8 %, and the median onset time was 23.7 days (interquartile range, 14-30 days). The Kaplan-Meier survival curve showed that a serum creatine kinase (CK) level > 175.5 U/L and initial Glasgow Coma Scale (GCS) score ≤ 9 were associated with a higher cumulative incidence of DNS (log-rank test; p < 0.01 and p = 0.02, respectively). Cox regression analysis showed that a serum CK level > 175.5 U/L (hazard ratio [HR]: 2.862, 95 % confidence interval [CI]: 1.491-5.496; p < 0.01) and an initial GCS ≤ 9 (HR: 2.081, 95 % CI: 1.048-4.131; p = 0.04) were significant prognostic factors.

CONCLUSION

In acute CO poisoning, an initial GCS score ≤ 9 and serum CK level > 175.5 U/L are significant predictors of DNS development.

Factors Contributing to CO Uptake and Elimination in the Body: A Critical Review

BACKGROUND

Carbon monoxide (CO) poisoning is an important public health issue around the world. Research indicates that many factors may be related to the rate of CO uptake and elimination in the human body. However, some factors related to CO uptake and elimination are considered controversial. Relatively little attention has been devoted to review and synthesis of factors affecting CO uptake and elimination.

PURPOSE

This paper provides a critical scoping review of the factors and divides them into four aspects, including environmental, demographic, physiological and treatment factors.

METHODS

We searched the scientific databases for research that has proposed a mathematical equation as a synthesis of quantities related to CO poisoning, CO elimination, CO uptake, CO half-life, CO uptake and elimination and their relationships. After excluding the studies that did not meet the study criteria, there were 39 studies included in the review and the search was completed before 16 December 2019.

RESULTS AND CONCLUSION

This review discusses most of the factors that impact the rate of CO uptake and elimination. Several factors may be related to CO uptake and elimination, such as CO concentration, the duration of exposure to CO, age, sex, exercise, minute ventilation, alveolar ventilation, total haemoglobin mass and different treatments for CO poisoning. Although some potential factors were not included in the review, the findings are useful by presenting an overview for discussing factors affecting CO uptake and elimination and provide a starting point for further study regarding strategies for CO poisoning and the environmental standard of CO.