Some years ago, Terri Monk suggested that patients had prolonged BIS <45 were more likely to be dead a year later. Other researchers did not reproduce her findings.
Subsequently, researchers at the Cleveland Clinic found that patients who had “triple low” conditions did poorly. What’s a “triple low?”
MAP less than 75 mmHg
BIS less than 45, and
MAC fraction less than 0.8
However, the accompanying editorial suggests that “triple lows” may not cause M&M, but rather identify higher risk patients:
Triple low may be a similar phenomenon: an objective measure of the historically subjective concept of patient frailty.
Now, new research from Duke refutes the “triple low” hypothesis. Once they adjusted for patient comorbidity, especially cancer, “triple low didn’t predict outcome.
The results of that study indicated that BIS values less than 45 are likely markers of systemic illness, poor cardiac function, or complicated intraoperative course.10
I think we are anxious to find interventions we can do to improve outcome – I think that explains much of the beta blocker saga. Perhaps the better course is “Primum non nocere?”