Predictors for Delayed Encephalopathy Following Acute Carbon Monoxide Poisoning

Kaoru Kudo; Kotaro Otsuka; Junko Yagi; Katsumi Sanjo; Noritaka Koizumi; Atsuhiko Koeda; Miki Yokota Umetsu; Yasuhito Yoshioka; Ayumi Mizugai; Toshinari Mita; Yu Shiga; Fumito Koizumi; Hikaru Nakamura; Akio Sakai

Disclosures

BMC Emerg Med. 2014;14(3) 

In This Article

Results

The mean age of all 79 cases was 40.44 years (men, 43.0 ± 14.23 years; women, 35.0 ± 12.57 years). Nineteen cases (24%) were transferred to the Hospital from their previous respective medical institutions to which they were first brought, on the grounds of difficulty providing care. The 13 cases who developed DNS consisted of 11 men and 2 women and had a mean age of 47.38 ± 14.83 years, two of who had been transferred from another hospital. In terms of type of DNS, 5 cases had intermittent CO poisoning, whereas the remaining 8 cases included cases of prolonged CO poisoning and those of persistent apallic syndrome (see the Table 1). The mean period before the onset of intermittent CO poisoning was 23.2 days of illness.

Patients' Background and Circumstances

While the mean age was higher in the DNS-developing group by approximately 7 years, there was no significant difference between the two groups. Although approximately 80% of all cases were men, there was no significant difference in the development of DNS between male and female cases. Place of exposure to CO was broadly classified into car and room, with no significant difference between the DNS-developing and non-DNS-developing groups. Estimated duration of exposure was unknown for approximately 50% of all cases, with no significant difference between the DNS-developing and non-DNS-developing groups.

Physical Findings and Laboratory Results at First Consultation

The patients in the DNS-developing group had significantly more severe consciousness disturbance (in terms of mean JCS score) at the time of first hospital consultation (p<0.001). A significantly higher proportion of these patients showed abnormal head CT findings indicating hypoxic encephalopathy (p<0.001). Hematology results showed that these patients also had significantly higher CK, CK-MB and LDH levels (p = 0.001, p<0.001 and p<0.001, respectively). The GAS scores of these patients, which assess their psychiatric symptoms, tended to be significantly lower than in the non-DNS-developing group (p = 0.033).

Overall, F3 was the single most common main diagnosis according to ICD-10, followed by F4, which was a tendency also shared by both groups. Severity of psychiatric symptoms (BPRS score) and life events (mean LCU score) showed no significant difference between the groups.

CO-Hb levels at the time of first hospital consultation were higher in the non-DNS-developing group, whereas WBC count was higher in the DNS-developing group, with neither showing a significant difference.

Clinical Course After Hospitalization

Of the items to assess the clinical course after hospitalization, length of hospital stay (p<0.001) and the number of HBO therapy sessions (p<0.001) showed a significant difference between the two groups, with the DNS-developing group having longer hospital stay and a larger number of sessions. In the DNS-developing group, the period of time before the onset of intermittent CO poisoning ranged from 17 to 35 days (mean: 23.2 days of illness). Whether or not HBO therapy was administered immediately after consultation was not significantly different between the two groups.

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