Ischemic changes in evoked spinal cord potentials during profound hypothermic circulatory arrest in thoracic aortic surgery.
OBJECTIVE
We examined the changes in evoked spinal cord potentials (ESCP) during profound hypothermic circulatory arrest to estimate the safe ischemic time.


METHODS
We monitored ESCPs during surgery for descending thoracic or thoracoabdominal aneurysms in five patients. Evoked spinal cord potential recordings were obtained before cooling (baseline), then every few minutes during circulatory arrest, and at the end of the operation.


RESULTS
After circulatory arrest, the amplitude of ESCPs decreased with time. We calculated the simple linear regression between the amplitude of ESCPs and the circulatory arrest time by the least-squares method, and found a highly linear relationship between amplitude and arrest time in all five patients. The time until disappearance of ESCPs was estimated as 50.7 +/- 20.4 min (95% level of confidence).


CONCLUSIONS
When an ESCP disappeared, ischemic spinal cord injury had occurred. This demonstrates the potential value of estimating the time of disappearance of ESCPs to prevent ischemic spinal cord injury during descending thoracic aortic surgery.
Kotoh
Keiju
K
Department of Surgery, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama, 930-0194, Japan.
Fukahara
Kazuaki
K
Yamashita
Akio
A
Seki
Kouiti
K
Misaki
Takuro
T
D000368:Aged; D001014:Aortic Aneurysm / Q000601:surgery*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects*; D007431:Intraoperative Complications / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D007511:Ischemia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D013116:Spinal Cord / Q000098:blood supply* / Q000503:physiopathology