title: The effects of pulsatile cardiopulmonary bypass on cerebral and renal blood flow in dogs.
abstract: OBJECTIVE
  The purpose of this study was to determine the effects of pulsatility on cerebral blood flow, cerebral metabolism, and renal blood flow over a range of cardiopulmonary bypass temperature and flow conditions.
  
  
  METHODS
  The investigation was prospective, randomized, and performed in a canine physiology laboratory at the Mayo Foundation.
  
  
  METHODS
  Anesthetized dogs were studied during pulsatile (n = 9) or nonpulsatile (n = 10) cardiopulmonary bypass at two flow rates (2.4 and 1.2 L/min/m2) at each of three temperatures (37 degrees, 32 degrees, and 27 degrees C). Pulsatility was achieved by use of a pediatric intraaortic balloon pump. Cerebral blood flow and metabolic rate were determined using the sagittal sinus outflow method. Renal blood flow was determined by a periarterial ultrasonic flow probe.
  
  
  RESULTS
  In the pulsatile group, a pulse pressure of 29 mmHg had no effect on cerebral blood flow or metabolism at any temperature under either flow condition. Renal blood flow was also unaffected by pulsatility, but decreased with hypothermia and reduced pump flow. Pulsatility also did not attenuate the systemic effects of normothermic hypoperfusion.
  
  
  CONCLUSIONS
  Pulsatility has no significant effect on cerebral or renal perfusion over a broad range of cardiopulmonary bypass temperature and flow conditions. Cerebral blood flow and metabolism were functions of temperature but not pulsatility or flow rate. Renal blood flow was affected by both temperature and cardiopulmonary bypass flow rate but not by pulsatility. Finally, central nervous system perfusion may be preserved under low-flow cardiopulmonary bypass conditions by shunting of perfusion from splanchnic vascular beds.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Cook
authors.forename: T A
authors.initials: TA
authors.lastname: Orszulak
authors.forename: R C
authors.initials: RC
authors.lastname: Daly
mesh_terms: D000818:Animals; D001794:Blood Pressure; D001831:Body Temperature; D001921:Brain / Q000378:metabolism; D002315:Cardiopulmonary Bypass / Q000379:methods*; D002560:Cerebrovascular Circulation; D003392:Cranial Sinuses / Q000502:physiology; D004285:Dogs; D004569:Electroencephalography; D007036:Hypothermia, Induced; D007423:Intra-Aortic Balloon Pumping / Q000295:instrumentation; D007668:Kidney / Q000000981:diagnostic imaging; D010101:Oxygen Consumption; D011446:Prospective Studies; D011673:Pulsatile Flow; D011897:Random Allocation; D012039:Regional Blood Flow; D012079:Renal Circulation; D012212:Rheology; D013152:Splanchnic Circulation; D013696:Temperature; D014463:Ultrasonography