Radial-to-femoral pressure gradient quantification in cardiac surgery

Abstract

Background: A radial-to-femoral pressure gradient (RFPG) can occur in roughly one-third of cardiac surgical patients. Such a gradient has been associated with smaller stature and potentially smaller radial artery diameter. We hypothesized that preoperative radial artery diameter could be a predictor of RFPG. We also investigated the clinical impact of using a femoral versus a radial arterial catheter in terms of vasoactive support.

Methods: Using ultrasound, we measured the bilateral radial artery diameters of 160 cardiac surgical patients. All arterial pressure values were continuously recorded. Significant RFPG was defined as ≥25 mm Hg in systolic and/or ≥10 mm Hg in mean arterial pressure. One hundred and forty-nine additional patients were used to validate the impact of our observations.

Results: Using 78,013 pressure datapoints in 129 patients, 34.8% of patients had an RFPG with a mean duration of 54 ± 48 minutes. Patients with a radial artery diameter <1.8 mm were more likely to have an RFPG (n = 14 [48.3%] vs 12 [22.2%]; P = .042). Patients with only a radial catheter received more phenylephrine (P = .016) despite undergoing shorter and less complex procedures. In the validation cohort, similar observations were made, and patients with a radial artery catheter received a longer duration of vasoactive support in the intensive care unit.

Conclusions: A significant RFPG occurs in one-third of cardiac surgical patients and in 48% of those with a radial artery diameter <1.8 mm. The use of a single radial arterial catheter instead of dual radial and femoral catheters was associated with greater vasopressor requirements in the operating room and in the intensive care unit. We do not recommend the use of a single radial artery catheter in cardiac surgery.

Keywords: BMI, body mass index; BSA, body surface area; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; ICU, intensive care unit; IQR, interquartile range; RFPG, radial-to-femoral pressure gradient; cardiac surgery; femoral arterial pressure; radial arterial pressure; radial-to-femoral arterial pressure gradient; vasoactive support.

Graphical abstract

Radial-to-femoral arterial pressure gradient in cardiac surgery.

Figure 1

Radial (Pra) and femoral arterial pressures (Pfa) in a 60-year-old man undergoing coronary revascularization. A, No significant difference in the Pra and Pfa before cardiopulmonary bypass (CPB). B, Note the significant mean gradient of 38 mm Hg that appears during CPB. C, Despite a Pra of 28 mm Hg, brain saturation (rSO₂) and transcranial Doppler (109% from baseline) were normal. D, Intraoperative evolution of the Pfa (white) and Pra (green) during CPB. Note the significant gradient that appears only during CPB. HR, Heart rate; TCD, transcranial Doppler; PSV, peak systolic velocity; MV, mean velocity; EDV, end-diastolic velocity; PI, pulsatility index; Ppa, pulmonary artery pressure.

Figure 2

A and B, Radial (Pra) and femoral arterial pressure (Pfa) in a 75-year-old man before (A) and after (B) cardiopulmonary bypass (CPB) for aortic valve replacement. There was no difference in the Pra and Pfa before CPB; however, note the significant systolic (47 mm Hg) and mean (17 mm Hg) radial-to-femoral pressure gradient (RFPG) after CPB. C, This patient had significant high-intensity transient signals (HITS) after weaning from CPB, resulting in brain desaturation and associated with hemodynamic instability. D, Postoperative evolution of the Pra (green) and Pfa (white) in a 76-year-old man after revascularization. Note the RFPG that appeared during CPB but became highly significant after CPB. HR, Heart rate; TCD, transcranial Doppler; PSV, peak systolic velocity; MV, mean velocity; EDV, end-diastolic velocity; PI, pulsatility index; Δ%, change from baseline; Ppa, pulmonary artery pressure.

Figure 3

A, Radial (Pra) and femoral arterial pressure (Pfa) evolution in a 54-year-old man undergoing a Ross procedure. Note the significant systolic radial-to-femoral gradient from the beginning, during cardiopulmonary bypass (CPB), and until the end of the procedure. B, Brain saturation % change (%rSO₂) was normal during the procedure except after weaning from CPB, when it dropped transiently. AUC, Area under the curve; ΔSpO₂, change in saturation measured with pulse oximetry; ΔO₂Hbi, change in oxyhemoglobin index; ΔHHbi, change in deoxyhemoglobin index; ΔcHbi, change in total hemoglobin index.

Figure 4

Radial-to-femoral pressure gradient and tertile groups of radial artery diameter (RAD). BP, Blood pressure; CPB, cardiopulmonary bypass.

Figure 5

Study summary of the prospective study of 278 patients in which a significant radial-to-femoral arterial pressure gradient (RFPG) was observed in 34.8% of all patients and in 48% of those with a radial artery diameter <1.8 mm. In those patients with only a radial artery pressure, increased use of phenylephrine was observed, and in another cohort, the duration of postoperative vasoactive agent use was longer in the intensive care unit. Intra-op, Intra-operative period; Post-op, post-operative period; Rx, medication.

Figure E1

(A) Two-dimensional view of the radial artery (B) using color Doppler.

Figure E2

Flowchart of patient inclusion.