Microcirculatory Perfusion is Preserved during Off-Pump but not On-Pump Cardiac Surgery

OBJECTIVE:

This study investigated the perioperative course
of microcirculatory perfusion in off-pump compared with on-pump surgery.
Additionally, the impact of changes in systemic hemodynamics,
hematocrit, and body temperature was studied.

DESIGN:

Prospective, nonrandomized, observational study.

SETTING:

Tertiary university hospital.

PARTICIPANTS:

Patients undergoing coronary artery bypass grafting with (n = 13) or without (n = 13) use of cardiopulmonary bypass.

INTERVENTIONS:

Microcirculatory measurements were obtained at 5 time points ranging from induction of anesthesia to ICU admission.

MEASUREMENTS AND MAIN RESULTS:

Microcirculatory
recordings were performed with sublingual sidestream dark field
imaging. Despite a comparable reduction in intraoperative blood pressure
between groups, the perfused vessel density decreased more than 20%
after onset of extracorporeal circulation but remained stable in the
off-pump group. The reduction in microvascular perfusion in the on-pump
group was further paralleled by decreased hematocrit and temperature.
Although postbypass hematocrit levels and body temperature were restored
to similar levels as in the off-pump group, the median microvascular
flow index remained reduced after bypass (2.4 [2.3-2.7]) compared with
baseline (2.8 [2.7-2.9]; p = 0.021).

CONCLUSIONS:

Microcirculatory
perfusion remained unaltered throughout off-pump surgery. In contrast,
microvascular perfusion declined after initiation of cardiopulmonary
bypass and did not recover in the early postoperative phase.