HMPAO SPECT Brain Imaging of Acute CO Poisoning and Delayed Neuropsychological Sequelae (DNSS). PG Harch, KW Van Meter, SF Gottlieb, P Staab. JoEllen Smith Hyperbaric Medicine Unit, New Orleans, LA 70131

Background: Brain CT and MRI are poor barometers of acute CI poisoning and the DNSS syndrome, registering abnormalities in a minority of patients. HMPAO SPECT, a flow metabolism modality, seems more appropriate. We report 12 cases of acute poisoning and DNSS imaged with HMPAO SPECT/

Methods: All patients, acute CO poisoning (11) or DNSS (1) were imaged with HMPAO pre, post &Mac179; 1 HBOT, or pre and post (bracketing scans—Neubauer/Gottlieb technique) a single BHOT on an ADAC dual head or Picker Prism 3000. Bracketed scans used a split dose, injected 6 h (1 half-life) apart. Treatment was a multi-place table (66 fsw/51 mins, 33 fsw/55 mins, plus air breaks) plus HBOT (1.5-2.0 ATA/90 mins) in 11/12 patients, HBOT alone (33 fsw/90 mins) in one.

Results: There were 12 cases (4 _, 8 _), average age 41 (3-88). Diagnosis was presumptive in 2 cases (1 acute, 1 DNSS); CO level was 26 (16.6-46) in 10 cases, drawn 1.2 h (.5-3) post extrication. Length of exposure was 8.1h (1-22; 3 cases estimated) in 11 cases; 1 unknown. Delay to HBOT was 5.9h (3-10) in 11 cases. DNSS presented 13.6d post exposure in 5 patients (4-21), 4 of whom had previously been treated. Time to SPECT post exposure was 11.3h (3-24) in 8 patients (3 pre HBOT) and 4, 4, 21, 88d in 4 others (1 pre HBOT). 11/12 cases had abnormal scans: diffuse patchy cortical uptake and focal cortical and deep grey matter deficits. 5 had bracketing scans, 4/5 showed improvement. 2 had scans pre and at the end of HBOT; both were improved and tracked the clinical conditions. One of these, a retarded patient, showed changes on 4 scans reflecting acute poisoning, single HOBT, DNSS, and repeat HBOT that helped guide HBOT in her and her 12 year old sister in the absence of ability to report symptoms. 4/5 DNSS patients’ scans were abnormal.

Conclusion: SPECT brain imaging with O2 intervention sensitively reflects CO poisoning and DNSS, helps identify potentially recoverable brain tissue, gauge the effects of HBOT, and determine clinical endpoints, especially in patients incapable of reporting subtle symptoms (children).