[Prognostic estimation of cerebral arterio-venous difference of oxygen content (c-AVDO2) on severe head injury patients].

UNLABELLED

Cerebral arterio-venous difference in oxygen content (c-AVDO2) was calculated in 10 patients suffering from severe head injury with brain contusion as the chief morbid condition [consciousness on admission: under 10 on the Glasgow Coma Scale (GCS); 5 survived and 5 died), in order to re-evaluate the importance of c-AVDO2 as a factor of prognosis evaluation in patients with severe head injury. Indwelling catheters were placed in the femoral artery and jugular vein on the side of the brain contusion in all patients on admission, and blood samples were collected when necessary for calculation of c-AVDO2. Whenever blood samples were collected, GCS-based evaluation of consciousness and determination of auditory brainstem response (ABR) (a V-wave latency period of 5.67 + 0.40 msec. or more was considered to indicate prolongation) were performed. In 6 patients (2 survived and 4 died) who underwent monitoring of epidural pressure (EDP), this was confirmed on blood sample collection. c-AVDO2 was (1) compared between patients who survived and those who died, and studied in terms of (2) consciousness, (3) ABR and (4) EDP.

RESULTS

(1) c-AVDO2 was 8.23 +/- 0.78 ml% in patients who survived and 4.94 +/- 0.71 ml% in those who died. (2) c-AVDO2 in patients with GCS values of 15-11, 10-7, and 6-3 was 7.85 +/- 1.41 ml%, 7.70 +/- 1.53 ml% and 5.09 +/- 1.27 ml%, respectively. (3) c-AVDO2 when the V-wave latency periods of ABR were less than 6.07 msec. and greater than or equal to 6.07 msec. was 7.13 +/- 1.74 ml% and 6.51 +/- 2.29 ml%, respectively, and when the latency disappeared c-AVDO2 was 3.74 +/- 0.62 ml%. (4) c-AVDO2 at EDP values of 10-40 mmHg, 41-70 mmHg and 71 mmHg or more was 6.99 +/- 1.53 ml%, 6.23 +/- 2.36 ml% and 4.15 +/- 0.35 ml%, respectively.

CONCLUSIONS

(1) The c-AVDO2 in the patients who died was significantly lower than that in the patients who survived. (2) All of the patients who showed a c-AVDO2 of 5 ml% or less at least once dies, suggesting that the critical point of poor absolute prognosis is 5 ml%.