Carbon monoxide poisoning: correlation of neurological findings between accident and emergency departments and a hyperbaric unit.

OBJECTIVES: To investigate and quantify the differences in neurological examination findings in patients acutely poisoned with carbon monoxide, between initial assessment at accident and emergency (A&E) departments and subsequently at a hyperbaric unit.
METHODS: Retrospective case note review of all patients referred to the Hull Hyperbaric Unit for treatment of acute carbon monoxide poisoning between August 1998 and August 1999. Patients who were ventilated or less than 16 years old were excluded because of difficulty in assessing their neurological status.
RESULTS: Thirty patients were included for analysis. The mean duration from exposure to assessment in A&E was four hours while patients were reviewed on average three hours later at the hyperbaric unit. Referrals came from 14 different hospitals. A history of loss of consciousness accounted for 70% of referrals. A mean of 3.2 neurological signs per patient was documented in A&E compared with 9.2 at the hyperbaric unit. Seventy nine per cent of abnormal neurological signs were not detected at A&E departments compared with 3% at the hyperbaric unit. The major source of discrepancy was in sharpened Rhomberg's test and heel-toe gait, in 13% of patients examined in A&E departments these signs were recorded as abnormal compared with 90% at the hyperbaric unit.
CONCLUSION: There is a large discrepancy in neurological findings between assessment in A&E departments and the Hull Hyperbaric Unit. A number of factors may account for this including interobserver variation, patient deterioration during transfer, poor documentation, lack of understanding of the sequelae of carbon monoxide poisoning and inadequate examinations. Further research is required to quantify the impact of the various factors that may contribute to the differences in neurological findings.