title: Risk Factors Involved in Central-to-Radial Arterial Pressure Gradient During Cardiac Surgery.
abstract: BACKGROUND
  A central-to-radial arterial pressure gradient may occur after cardiopulmonary bypass (CPB), which, in some patients, may last for a prolonged time after CPB. Whenever there is a pressure gradient, the radial artery pressure measure may underestimate a more centrally measured systemic pressure, which may result in a misguided therapeutic strategy. It is clinically important to identify the risk factors that may predict the appearance of a central-to-radial pressure gradient, because more central sites of measurements might then be considered to monitor systemic arterial pressure in high-risk patients. The objective of this study was to assess preoperative and intraoperative risk factors for central-to-radial pressure gradient.
  
  
  METHODS
  Seventy-three patients undergoing cardiac surgery using CPB were included in this prospective observational study. A significant central-to-radial arterial pressure gradient was defined as a difference of 25 mm Hg in systolic pressure or 10 mm Hg in mean arterial pressure for a minimum of 5 minutes. Preoperative data included demographics, presence of comorbidities, and medications. Intraoperative data included type of surgery, CPB and aortic clamping time, use of inotropic drugs, and vasodilators or vasopressors agents. The diameter of the radial and femoral artery was measured before the induction of anesthesia using B-mode ultrasonography.
  
  
  RESULTS
  Thirty-three patients developed a central-to-radial arterial pressure gradient (45%). Patients with a significant pressure gradient had a smaller weight (71.0 ± 16.9 vs 79.3 ± 17.3 kg, P = 0.041), a smaller height (162.0 ± 9.6 vs 166.3 ± 8.6 cm, P = 0.047), a smaller radial artery diameter (0.24 ± 0.03 vs 0.29 ± 0.05 cm, P < 0.001), and were at a higher risk as determined by the Parsonnet score (30.3 ± 24.9 vs 17.0 ± 10.9, P = 0.007). In addition, a longer aortic clamping time (85.8 ± 51.0 vs 64.2 ± 29.3 minutes, P = 0.036), mitral and complex surgery (P = 0.007 and P = 0.017, respectively), and administration of vasopressin (P = 0.039) were identified as potential independent predictors of a central-to-radial pressure gradient. By using multivariate logistic regression analysis, the following independent risk factors were identified: Parsonnet score (odds ratio [OR], 1.076; 95% confidence interval [CI], 1.027-1.127, P = 0.002), aortic clamping time >90 minutes (OR, 8.521; 95% CI, 1.917-37.870, P = 0.005), and patient height (OR, 0.933, 95% CI, 0.876-0.993, P = 0.029). The relative risk (RR) estimates remained statistically significant for the Parsonnet score and the aortic clamping time ≥90 minutes (RR, 1.010; 95% CI, 1.003-1.018, P = 0.009 and RR, 2.253; 95% CI, 1.475-3.443, P < 0.001 respectively) while showing a trend for patient height (RR, 0.974; 95% CI, 0.948-1.001, P = 0.058).
  
  
  CONCLUSIONS
  Central-to-radial gradients are common in cardiac surgery. The threshold for using a central site for blood pressure monitoring should be low in small, high-risk patients undergoing longer surgical interventions to avoid inappropriate administration of vasopressors and/or inotropic agents.
authors.affiliation: From the Departments of Anesthesiology and Cardiac Surgery, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada; Coordinating Center, Montreal Heart Institute, Montreal, Quebec, Canada; and Department of Preventive and Social Medicine, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Fuda
authors.forename: André
authors.initials: A
authors.lastname: Denault
authors.forename: Alain
authors.initials: A
authors.lastname: Deschamps
authors.forename: Denis
authors.initials: D
authors.lastname: Bouchard
authors.forename: Annik
authors.initials: A
authors.lastname: Fortier
authors.forename: Jean
authors.initials: J
authors.lastname: Lambert
authors.forename: Pierre
authors.initials: P
authors.lastname: Couture
mesh_terms: D000368:Aged; D062186:Arterial Pressure; D006348:Cardiac Surgical Procedures / Q000379:methods*; D002315:Cardiopulmonary Bypass; D015897:Comorbidity; D003250:Constriction; D004347:Drug Interactions; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017534:Radial Artery / Q000503:physiopathology*; D012307:Risk Factors; D014662:Vasoconstrictor Agents / Q000009:adverse effects / Q000627:therapeutic use; D014667:Vasopressins / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D014662:Vasoconstrictor Agents; D014667:Vasopressins