Re:Preoperative Beta-blockade: Unanswered Questions

Sonia Bouri, Doctor,

Other Contributors:

August 15, 2013

Metoprolol Dosing

We thank Dr Cohn for pointing out that our description[1] of the POISE dosage described only the first dose. The general maintenance dose was 200 mg extended release once a day (equivalent to 50 mg immediate release three times a day). If systolic pressure dropped below 100 mmHg, or heart rate below 50 bpm, beta-blockade was paused and later restarted at 100 mg od.

Moreover, as Dr Cohn points out, the metoprolol was given twice. The first was 2 - 4 hours before surgery. The surgery then lasted a variable time. During the first 6 hours of recovery, if the heart rate was above 80 bpm and the blood pressure above 100 mmHg, the second dose was given. If the blood pressure was above 100 mg but the heart rate only between 50 and 80, the second dose was given only at the end of the 6 hours.

No patients received the protocol permitted theoretical dosage of 400 mg in the initial 24 hours[2].

Causation

We can see Dr Cohns' point that causation can never really be proved in medicine. The statistically significant increased mortality was merely the result of the randomised controlled trial data.

Dr Cohns' Conclusions

We thank Dr Cohn for encapsulating more elegantly than we managed ourselves, the conclusions of our paper.

References

1. Bouri S et al. Meta-analysis of secure randomised controlled trials of ?-blockade to prevent perioperative death in non-cardiac surgery. Heart 2013. doi: 10.1136/heartjnl-2013-304262.

2. Poldermans D, Devereaux P J. The experts debate:Perioperative beta -blockade for noncardiac surgery - proven safe or not? CCJM 2009;76: S84- 92]

Conflict of Interest:

None declared

Conflict of Interest

None declared