title: Pulsatile versus nonpulsatile flow during cardiopulmonary bypass: microcirculatory and systemic effects.
abstract: BACKGROUND
  Controversy exists regarding the optimal perfusion modality during cardiopulmonary bypass (CPB). Here we compare the effects of pulsatile versus nonpulsatile perfusion on microvascular blood flow during and after CPB.
  
  
  METHODS
  High-risk cardiac surgical patients were randomly assigned to have pulsatile (n=10) or nonpulsatile (n=10) flow during CPB. The sublingual microcirculation was assessed using orthogonal polarization spectral imaging. Hemodynamic and microvascular variables were obtained after anesthesia (baseline), during CPB, and post-CPB.
  
  
  RESULTS
  Compared with baseline, a normal microcirculatory blood flow pattern was accomplished at all time points under pulsatile flow conditions. Peaking 24 hours postoperatively, a higher proportion of normally perfused microvessels occurred under pulsatile versus nonpulsatile flow (56.0%±3.9% vs 33.3%±4.1%; p<0.05). Concurrently, pulsatility resulted in a reduction in the prevalence of pathologic hyper-dynamically perfused vessels (6.0%±3.4% vs 19.6%±8.8%; p<0.05). Leukocyte adherence decreased relative to the nonpulsatile group both during and after CPB. Furthermore, peak lactate levels were reduced under pulsatile flow conditions postoperatively.
  
  
  CONCLUSIONS
  Pulsatile perfusion is superior to nonpulsatile perfusion at preserving the microcirculation, which may reflect attenuation of the systemic inflammatory response during CPB. We suggest the implementation of pulsatile flow can better optimize microvascular perfusion, and may lead to improved patient outcomes in high-risk cardiac surgical procedures requiring prolonged CPB time.
authors: Department of Surgery, Division of Cardiac Surgery, London Health Sciences Centre, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.
authors: Michael P
authors: MP
authors: O'Neil
authors: Jennifer C
authors: JC
authors: Fleming
authors: Amit
authors: A
authors: Badhwar
authors: Linrui Ray
authors: LR
authors: Guo
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000379:methods*; D002315:Cardiopulmonary Bypass / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006331:Heart Diseases / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D009061:Mouth Mucosa / Q000098:blood supply*; D011446:Prospective Studies; D011673:Pulsatile Flow / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology*; D016896:Treatment Outcome