The effects of pulsatile and non-pulsatile cardiopulmonary bypass on renal blood flow and function

The physiologic effects of pulsatile and non-pulsatile flow in cardiopulmonary bypass were compared in terms of the relationship between different flow rates and what effects these had on pulsatile and non-pulsatile flow. Forty adult mongrel dogs were used in this study and divided into 5 groups, each comprised of 8 animals, according to the flow rate during cardiopulmonary bypass, namely; 40, 60, 80, 100, or 120 ml/kg/min. The animals were perfused with either pulsatile or non-pulsatile flow for 1 hour, given randomly at the same mean flow rate. At flow rates of 80 and 100 ml/kg/min, the mean arterial blood pressure and total peripheral vascular resistance were significantly lower in pulsatile flow than in non-pulsatile flow, and the renal blood flow was significantly greater in pulsatile flow than in non-pulsatile flow. The renal arterial-venous lactate difference was significantly less in pulsatile flow than in non-pulsatile flow at a flow rate of 80 ml/kg/min, and the renal lactate extraction was significantly higher in pulsatile flow than in non-pulsatile flow at the same flow rate. The renal excess lactate was significantly lower in pulsatile flow than in non-pulsatile flow at a flow rate of 100 ml/kg/min. There were no significant differences in these parameters between the two types of perfusion at flow rates of 40, 60 or 120 ml/kg/min. Pulsatile flow was therefore apparently advantageous, when compared to non-pulsatile flow, in terms of hemodynamics, renal circulation, and metabolism of the kidney at flow rates of 80 and 100 ml/kg/min. However, when the flow rate was 120 ml/kg/min, pulsatile flow and non-pulsatile flow had the same effects.     

The effects of pulsatile and non-pulsatile cardiopulmonary bypass on renal blood flow and function

The physiologic effects of pulsatile and non-pulsatile flow in cardiopulmonary bypass were compared in terms of the relationship between different flow rates and what effects these had on pulsatile and non-pulsatile flow. Forty adult mongrel dogs were used in this study and divided into 5 groups, each comprised of 8 animals, according to the flow rate during cardiopulmonary bypass, namely; 40, 60, 80, 100, or 120 ml/kg/min. The animals were perfused with either pulsatile or non-pulsatile flow for 1 hour, given randomly at the same mean flow rate. At flow rates of 80 and 100 ml/kg/min, the mean arterial blood pressure and total peripheral vascular resistance were significantly lower in pulsatile flow than in non-pulsatile flow, and the renal blood flow was significantly greater in pulsatile flow than in non-pulsatile flow. The renal arterial-venous lactate difference was significantly less in pulsatile flow than in non-pulsatile flow at a flow rate of 80 ml/kg/min, and the renal lactate extraction was significantly higher in pulsatile flow than in non-pulsatile flow at the same flow rate. The renal excess lactate was significantly lower in pulsatile flow than in non-pulsatile flow at a flow rate of 100 ml/kg/min. There were no significant differences in these parameters between the two types of perfusion at flow rates of 40, 60 or 120 ml/kg/min. Pulsatile flow was therefore apparently advantageous, when compared to non-pulsatile flow, in terms of hemodynamics, renal circulation, and metabolism of the kidney at flow rates of 80 and 100 ml/kg/min. However, when the flow rate was 120 ml/kg/min, pulsatile flow and non-pulsatile flow had the same effects.     

有创血压波形监测下体外循环搏动灌注效果初步评价

目的 探索桡动脉有创血压波形作为搏动灌注质控指标的可能性,并在此监测下评价搏动灌注的有效性.方法 选取2008年3月至12月需在体外循环下手术治疗的患者80例,随机分为搏动灌注组(P组)45例和非搏动灌注组(NP组)35例.主动脉阻断期间P组在桡动脉波形监测下建立搏动灌注,NP组采用常规平流灌注.将P组形成显著双峰波或单峰波(脉压差＞30 mm Hg,1 mm Hg=0.133 kPa)的病例与NP组比较,检测手术前后肌酐、尿素氮、血尿酸、乳酸脱氢酶、谷草转氨酶、超敏C反应蛋白,术中乳酸、尿量,手术后尿隐血率、心跳自复率、凝血酶原时间等指标.结果 P组有35例形成显著的双峰波形或单峰波.与NP组比较:术中乳酸较低(P＜0.01),单位时间尿量较多(P＜0.01),术后乳酸脱氢酶上升幅度(P＜0.05)、超敏C反应蛋白(P＜0.05)和凝血酶原时间(P＜0.01)较低.P组术后血尿酸下降,而NP组上升(P＜0.01);尿隐血、手术前后谷草转氨酶差率、心跳自复率两组差异无统计学意义.结论 通过设备优化和搏动参数的调控,能建立有效的搏动灌注和能最传递;桡动脉有创血压波形监测是方便有效的搏动灌注指标;在桡动脉波形监测下的搏动灌注各项监测指标明显优于平流灌注.     

The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion

The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion were compared with non-pulsatile pumping. Twelve dogs were classified into 2 groups by the perfusion technique used. Animals were core cooled to 20 degrees C esophageal temperature with 80 ml/kg/min perfusion rate and maintained at the level for 2 hours with low flow perfusion (LFP) (30 ml/kg/min), then rewarmed to 35 degrees C with 80 ml/kg/min flow rate. As compared with the non-pulsatile group, pulsatile group demonstrated greater urine output during rewarming (p less than 0.05) and greater lymph flow during core cooling (p less than 0.05). The non-pulsatile group showed higher lymph/plasma protein concentration ratio (Lc/Pc) during LFP and rewarming (p less than 0.05), and greater plasma protein clearance during rewarming (p less than 0.05), and much higher increase of interstitial fluid pressure. The lesser water retention during bypass was also noted in the pulsatile group (28.6 +/- 27.6 ml/kg vs 85.4 +/- 52.1 ml/kg, p less than 0.05). These findings have suggested that the pulsatile perfusion may be useful for the infant cardiopulmonary bypass reducing tissue edema and preserving better renal function.     

The comparative effects of pulsatile and nonpulsatile myocardial perfusion during cardiopulmonary bypass

The salutary effects of pulsatile perfusion (P) during clinical cardiopulmonary bypass (CPB) remain controversial. The notion exists that coronary blood flow may be enhanced by P, especially when a significant coronary stenosis occurs. In this study pressure-flow characteristics were assessed during CPB with and without P in 13 fibrillating dog hearts (37°C). Radionuclide microspheres measured transmural blood flow in normal myocardium (NR) and in regions supplied by collateral coronary arteries (CR) which restrict blood inflow at mean pump pressures of 80 and 50 mm Hg during either P or nonpulsatile perfusion (NP). Retrograde circumflex pressure (RCP) also served as an index of CR perfusion. At both pressures, mean myocardial blood flow to both NR and CR was not augmented by P despite aortic pulse pressures of approximately 50 mm Hg. Moreover, endocardial/epicardial flow ratios were unchanged from control in both regions after beginning pulsatile flow. At the same time, the mean RCP in CR was not affected by P even though a pulsatile pattern was transmitted across the collateral bed. Thus, the most significant factors affecting transmural blood flow during pulsatile CPB appear to be the coronary perfusion pressure and degree of inflow limitation, not the perfusion wave form. Therefore, any benefits which might be associated with clinical pulsatile perfusion during CPB appear to result from factors other than coronary blood flow augmentation.     

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass. II. The effects on adrenal secretion of cortisol

Previous studies have indicated that a significant reduction in plasma cortisol levels occurs during nonpulsatile cardiopulmonary bypass as a result of adrenocorticol hypofunction. The St?ckert pulsatile pump system described in Part I has been employed in a comparative study of plasma cortisol levels in 20 patients subjected to pulsatile or nonpulsatile perfusion during open-heart surgery. The plasma cortisol response pattern in the nonpulsatile group was identical to the pattern previously described, with no significant rise in cortisol levels during the period of perfusion. In the pulsatile group, however, plasma cortisol levels rose significantly during perfusion, reaching a mean level at the end of perfusion which was highly significantly greater than that in the nonpulsatile group (p less than 0.001). Correction of the plasma cortisol values for the effect of hemodilution was performed and, again, corrected cortisol values indicated a highly significant increase in end-bypass levels in the pulsatile groups (p less than 0.001). These results clearly indicate that the reduction in cortisol secretion during nonpulsatile bypass may be prevented by the use of pulsatile perfusion.     

A simple method of producing pulsatile flow during clinical cardiopulmonary bypass

A method using the intraaortic balloon to produce pulsatile flow during cardiopulmonary bypass is described. The technique has been employed in 26 patients, and there have been no complications.     

Thiopentone pharmacokinetics during cardiopulmonary bypass with a nonpulsatile or pulsatile flow

To evaluate possible factors affecting the pharmacokinetics of thiopentone during cardiopulmonary bypass (CPB), the present study was undertaken in patients scheduled for coronary artery bypass grafting and with in vitro experiments. The effects of nonpulsatile and pulsatile flow during CPB on the distribution and elimination of thiopentone were compared in 30 patients anaesthetized with fentanyl. The initial rapid phases of distribution of thiopentone were studied in 17 patients undergoing a nonpulsatile or pulsatile perfusion, to whom thiopentone 6 mg/kg was given as a rapid intravenous bolus during CPB. In order to study later distribution and early elimination of thiopentone, 13 patients perfused with a nonpulsatile or pulsatile flow received 6 mg/kg of the drug as a 15-min intravenous infusion before CPB. No differences in the pharmacokinetic parameters characterizing distribution and elimination of thiopentone were found between the patients undergoing nonpulsatile or pulsatile perfusion. As measured in 10 of the patients receiving the drug before the institution of CPB, no difference in plasma thiopentone level was observed in blood samples drawn simultaneously from a radial arterial cannula and a pulmonary artery catheter before, during and after CPB. This suggests that thiopentone is not sequestered in lungs during CPB. In vitro binding of thiopentone to the CPB equipment was studied in 6 experiments using a closed circuit. After a 60-min circulation time, only 50% of the predicted thiopentone level was recovered from the perfusate. It is concluded that replacing a nonpulsatile perfusion with a pulsatile one has no effect on the distribution and elimination of thiopentone in patients undergoing CPB. During CPB, thiopentone is sequestered in the extracorporeal circuit but not in the lungs.     

A simple device for achieving pulsatile flow during cardiopulmonary bypass.

We describe a simple modification of the roller pump capable of producing a pulsatile flow during extracorporeal circulation. The technique is simple and can be readily duplicated in any center that uses roller pumps for cardiopulmonary bypass. Studies are in progress to evaluate the advantages of this type of perfusion.     

Adrenocortical hormone levels during cardiopulmonary bypass with and without pulsatile flow

To determine the effect of hypothermic pulsatile and nonpulsatile cardiopulmonary bypass (CPB) with hemodilution on adrenocortical function we measured plasma levels of adrenocorticotropic hormone (ACTH), cortisol, aldosterone, and renin in two groups of patients. Group I, comprising 11 patients had routine CPB (nonpulsatile), and Group II, comprising 12 patients, had pulsatile flow during CPB (pulsatile). Both groups demonstrated comparable increases in cortisol, ACTH, and aldosterone with operation. Levels for all three hormones appeared to decline during CPB and then rose again in the post-CPB period. There were no significant differences between groups. Plasma renin activity gradually declined in a comparable manner in both groups. In the post-CPB period, renin activity was slightly higher in the nonpulsatile group (1.7 +/- 0.5 versus 0.8 +/- 0.2 ng/ml/hr, p less than 0.05). Correction for the effect of hemodilution demonstrated no decrease in cortisol and a slight increase in ACTH in both groups during CPB. Significant increases occurred in both groups during CPB in urinary Na+ excretion rate and urinary Na+/K+ ratio, more so for the nonpulsatile group. There was no correlation between urinary Na+/K+ ratios and either plasma cortisol or aldosterone levels. Thus routine CPB demonstrates no evidence of adrenocortical hypofunction and the addition of pulsatile flow produces little improvement.     

Pulsatile flow during cardiopulmonary bypass. Evaluation of a new pulsatile pump

Pulsatile cardiopulmonary bypass (CPB) has been suggested to be superior to nonpulsatile CPB. This report concerns a newly developed pulsatile pump for clinical use. It is designed as a positive displacement pump, with blood allowed to collect in a valved cavity from which it is ejected by the reciprocating action of a piston. Using a uniform procedure of anaesthesia and surgery, 14 pigs were subjected to CPB at 37 degrees C for 3 hours. The pulsatile pump was used in seven pigs and a conventional roller pump in the other seven. The wave-form of the pulse during pulsatile CPB was similar to that recorded in the pigs before bypass. The values for rate of pressure change with respect to time (dp/dt) obtained in the aorta were close to the pre-CPB values. No difference was found between the two groups with respect to platelet count or haemolysis. The investigated pulsatile device appeared to be reliable and easy to handle, and the pulsation it produced closely resembled the physiologic pulse-wave form.     

The effect of pulsatile perfusion on aortocoronary bypass grafting

To evaluate the effect of pulsatile perfusion on myocardial protection and peripheral circulation, 23 patients undergoing aortocoronary bypass grafting were studied by dividing two groups; one with pulsatile perfusion technique (11 patients) and the other with non-pulsatile (12 patients). The cardiac functional assessments were made on CI, LVSWI, PCWP, CVP at 3, 6, 12 and 24 hours after the operation and the enzyme (CPK, CPK-MB, LDH, GOT) sampling were performed on 1, 2, 4 and 7 days after the operation. The difference between esophageal and rectal temperature, and urine output during cardiopulmonary bypass, indicating the peripheral circulation, were also measured. From these clinical results, it is concluded that pulsatile perfusion method is to be beneficial in myocardial protection and peripheral circulation during operation of aortocoronary bypass grafting.