We appreciate the comments by Drs. Rothfield and Veselis concerning the updated report of the American Society of Anesthesiologists Task Force on Perioperative Visual Loss Associated with Spine Surgery.1Both have raised valid points regarding central venous pressure (CVP) monitoring. The issue of CVP reliability in determining intravascular volume status has indeed been of concern, and recent literature has suggested that CVP monitoring may not be an optimal means of measurement.2Alternatives for the assessment of intravascular volume are available, such as measurement of pulse pressure variation of the arterial waveform, although these newer measurements have limitations as well.3
The evidence presented by Drs. Rothfield and Veselis refers to the issue of CVP reliability in general rather than to the specific application of CVP monitoring in spine patients. As correctly pointed out, there are few data regarding its use in guiding fluid therapy for spine surgery patients positioned prone. During the update of the Advisory, the literature was found to be insufficient to provide further guidance; therefore, a compelling need to update the recommendation was not available.
We do agree that it would be preferable to not include CVP as a primary means to assess intravascular volume in this group of patients when other less invasive monitors are available. On the other hand, patients who are at “high risk” (i.e. , those who undergo spine procedures while positioned prone and who have prolonged procedures, experience substantial blood loss, or both) may already have CVP monitoring, and the information may still have potential benefit.
Referring to the recommendation itself, however, the Advisory did not mandate the use of CVP, but rather to “consider” it for high-risk patients. Until conclusive evidence can establish the complete lack of usefulness of this form of monitoring for determining intravascular volume and in guiding fluid therapy, there may be no harm in considering CVP findings during surgery in these patients. We thank Drs. Rothfield and Veselis for their insights, and we again plan to revisit this issue when we next update this practice advisory.
