最重症頭部外傷患者における心拍出量の低下について

DECREASED CARDIAC OUTPUT IN PATIENTS WITH MOST SEVERE HEAD INJURY

はじめに

　重度頭部外傷患者における血圧や脳血流の変動を測定した研究はみられる。しかし頭部外傷に伴なうこれらの血正行動態の変動を，全身の血流量である心拍出量の変動にまで追求した研究はほとんどみられない。

　本研究は重度頭部外傷患者において心拍出量の測定を行ない，死亡にいたる最重症頭部外傷患者においては心拍出量が著明に減少する事実を知った。そしてこの心拍出量減少の意義について検討した。

Cardiac output in patients with severe head injury is measured by indicator dilution method. The following results are observed in patients with most severe head injury :

1) Significant decrease in the cardiac output is observed.

2) Arterial hypotension is well correlated with decrease of cardiac output. Blood pressure is main-tained mainly by increased peripheral resistance.

3) Cardiac output is decreased at early stage and it reaches to the lowest level at the time of brain death. After the time of brain death, cardiac output remains at the lowest level (X +Sx=1.72 ± 0.08 /min/m²⁾).

4) Decrease of cardiac output occurs simultane-ously or prior to the decrease in peripheral resis-tance.

5) Oxygen consumption is also decreased. The limiting factor of decreased oxygen consumption is not the decreased oxygen content of arterial blood, but the decreased cardiac output.