Study objective
Evidence for red blood cell (RBC) transfusion thresholds in the intraoperative setting is limited, and current perioperative recommendations may not correspond with individual intraoperative physiological demands. Hemodynamics relevant for the decision to transfuse may include peripheral perfusion index (PPI). The objective of this prospective study was to assess the associations of PPI and hemoglobin levels with the risk of postoperative morbidity and mortality.

Design
Multicenter cohort study.

Setting
Bispebjerg and Hvidovre University Hospitals, Copenhagen, Denmark.

Patients
We included 741 patients who underwent acute high risk abdominal surgery or hip fracture surgery.

Interventions
No interventions were carried out.

Measurements
Principal values collected included measurements of peripheral perfusion index and hemoglobin values.

Methods
The study was conducted using prospectively obtained data on adults who underwent emergency high-risk surgery. Subjects were categorized into high vs. low subgroups stratified by pre-defined PPI levels (PPI: > 1.5 vs. < 1.5) and Hb levels (Hb: > 9.7 g/dL vs. < 9.7 g/dL). The study assessed mortality and severe postoperative complications within 90 days.

Main results
We included 741 patients. 90-day mortality was 21% (n = 154), frequency of severe postoperative complications was 31% (n = 231).

Patients with both low PPI and low Hb had the highest adjusted odds ratio for both 90-day severe postoperative complications (2.95, [1.62–5.45]) and 90-day mortality (3.13, [1.45–7.11]).

A comparison of patients with low PPI and low Hb to those with high PPI and low Hb detected significantly higher 90-day mortality risk in the low PPI and low Hb group (OR 8.6, [1.57–162.10]).

Conclusion
High PPI in acute surgical patients who also presents with anemia was associated with a significantly better outcome when compared with patients with both low PPI and anemia. PPI should therefore be further investigated as a potential parameter to guide intraoperative RBC transfusion therapy.