Cardiopulmonary Bypass In Adults Research Articles

Cerebral effects of cardiopulmonary bypass in adults

Cardiopulmonary bypass (CPB) provides both gas exchange and organ perfusion. It allows the heart to be stopped and cardiac surgery to proceed under optimal conditions. Although there have been significant refinements in technology, CPB is not a normal physiological state. It is responsible for adverse effects on a number of organ systems including the development of coagulopathies and pulmonary, neurological, renal and immune dysfunction. This article concentrates on the cerebral effects of CPB during coronary artery bypass grafting (CABG) and valve surgery. The spectrum of cerebral dysfunction associated with cardiac surgery varies from well-defined cerebral death, non-fatal cerebrovascular accidents, coma and encephalopathy to less specific neurocognitive dysfunction and postoperative delirium. Patients can also develop seizures, ophthalmological abnormalities and primitive reflexes. Although there is an impressive literature on the effects of CPB on cerebral function, there are still few clear evidence-based recommendations that can be made. Most recommendations are based on common sense (e.g. maintaining oxygenation, avoiding severe hypotension).

Evaluation of Mimesys® Phosphorylcholine (PC)-Coated Oxygenators during Cardiopulmonary Bypass in Adults

A new generation of coating extracorporeal circuitry with biocompatible polymers has entered the North American perfusion market. This new biomimetic coating process uses synthetic phosphorylcholine (PC) containing polymers to bond covalently to the surface of the Sorin Monolyth® oxygenator, under the brand name of Mimesys®. In part one of a three-part investigation, 160 Mimesys®-coated oxygenators were randomly evaluated against 36 uncoated oxygenators for blood flow, hemodynamic resistance, and pressure differentials. In part two, retrospective analysis of platelet data collected in this study was compared with platelet data collected from a previous investigation using uncoated Monolyth oxygenators with albumin and crystalloid perfusates. Part three examined the risk-adjusted oxygenators, compared with 71 case-matched patients treated with uncoated oxygenators. There was no difference found in the Mimesys-coated group, when compared to the control group, with regard to pressure differentials or hemodynamic resistance. However, we conclude that platelet protection with PC-coated Monolyth’s using crystalloid perfusates, was similar to platelet protection with albumin perfusates, and significantly better than uncoated Monolyths® using crystalloid perfusates.

Enquête nationale sur les perfusions cérébrales pour chirurgie de la crosse de l'aorte présentée lors des 10 es Journées d'Actualité en Perfusion, qui se sont tenues à Nice les 26, 27 octobre 2001

Objective: to determine the methods of perfusion and cerebral protection currently used in France during aortic arch surgery in adults. Methods: national survey using a questionnaire mailed to every center (43 public and 25 private) performing cardiopulmonary bypass in adults. Gathereddata were analyzed by centers. Results: a 77.9% return rate has been obtained ( n=53). 479 operations have been performed during the year 2000 in 49 centers (9.61±7.15 by center; range from 1 to 33). Almost half of the center used a single method to protect the brain (49.1%). Deep hypothermic circulatory arrest (<20° C) was still employed in more thanhalf of the centers (50.9%). However, 66% of the surgical groups modified their practice during the last few years toward less hypothermia (54% of the changing centers) and more cerebral perfusion (69% of the changing centers); 24.5% have planned modifications in the next future. The systemic arterial perfusion has been mostly achieved using femoral cannulae (91% of thecenters) but the axillary route has emerged yet (21% of the centers). Neuromonitoring is heterogeneous and often missing (71.7% of the centers). Aprotinin is used by 81.1% of the surgical groups to prevent postoperative blood loss. Conclusion: Despite the confidence that is still attributed to deep hypothermic circulatory arrest, the methods of perfusion and cerebral protection currently applied during aortic arch surgery are widely changing.

Cerebral Response to Hemodilution During Hypothermic Cardiopulmonary Bypass in Adults

We examined the cerebral response to changing hematocrit during hypothermic cardiopulmonary bypass (CPB) in 18 adults. Cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and cerebral oxygen delivery (CDO2) were determined using the nitrous oxide saturation technique. Measurements were obtained before CPB at 36 degrees C, and twice during 27 degrees C CPB: first with a hemoglobin (Hgb) of 6.2 +/- 1.2 g/dL and then with a Hgb of 8.5 +/- 1.2 g/dL. During hypothermia, appropriate reductions in CMRO2 were demonstrated, but hemodilution-associated increases in CBF offset the reduction in CBF seen with hypothermia. At 27 degrees C CPB, as the Hgb concentration was increased from 6.2 to 8.5 g/ dL, CBF decreased. CDO2 and CMRO2 were no different whether the Hgb was 6.2 or 8.5 g/dL. In eight patients in whom the Hgb was less than 6 g/dL, CDO2 remained more than twice CMRO2. This study suggests that cerebral oxygen balance during cardiopulmonary bypass is well maintained at more pronounced levels of hemodilution than are typically practiced, because changes in cerebral blood flow compensate for changes in hemoglobin concentration.

Cerebral Response to Hemodilution During Hypothermic Cardiopulmonary Bypass in Adults

Cerebral Response to Hemodilution During Hypothermic Cardiopulmonary Bypass in Adults

Inflammatory Mediators in Adults Undergoing Cardiopulmonary Bypass: Comparison of Centrifugal and Roller Pumps

Background. The nonocclusive centrifugal pump is used for cardiopulmonary bypass (CPB) and mechanical cardiac assistance. This study examined its impact on proinflammatory cytokine release. Methods. Forty-one patients undergoing elective coronary artery bypass grafting were randomized prospectively to either a standard roller pump group (n = 21) or a centrifugal vortex pump group (n = 20) for CPB. The two groups were well matched in age, sex, severity of disease, and duration of CPB and aortic cross-clamping. Plasma levels of the cytokines tumor necrosis factor-α, interleukin-1β, interleukin-6, and interleukin-8, as well as terminal complement, neutrophil counts, and leukocyte elastase, were analyzed before, during, and after CPB. Results. In both groups, traces of tumor necrosis factor-α were observed infrequently and interleukin-1β was not detected. Plasma levels of interleukin-6 and interleukin-8 increased during and after CPB, reaching a peak at 2 hours after protamine administration in both groups before returning toward baseline at 24 hours. The release of interleukin-6 was significantly greater in the centrifugal group ( p < 0.05), whereas the interleukin-8 concentration did not differ between the groups throughout the study period. Levels of terminal complement increased in both groups perioperatively, reaching a peak 30 minutes after protamine administration, whereas neutrophil counts and elastase peaked 2 hours after protamine administration. Plasma terminal complement, neutrophil counts, and elastase release were significantly higher in the centrifugal group ( p < 0.05). Peak terminal complement correlated ( r = 0.64, p < 0.01) with peak elastase in the centrifugal group only. Conclusions. This study confirms the proinflammatory nature of CPB in adults and demonstrates that use of the centrifugal pump induces a greater systemic inflammatory response than use of the standard roller pump.

Effect of pump flow rate on cerebral blood flow during hypothermic cardiopulmonary bypass in adults

Objective: The purpose of this study was to examine the effect of cardiopulmonary bypass flow rate on cerebral blood flow and cerebral metabolic rate for oxygen during hypothermic (27°C) cardiopulmonary bypass. Design, Setting, and Participants: The investigation was a prospective, randomized study in a tertiary care hospital setting. The 30 participants were volunteer adult cardiac surgical patients at a single institution. Interventions: The N20 saturation method of Kety and Schmidt was used to determine global cerebral blood flow and metabolic rate during four periods: prebypass, cardiopulmonary bypass (CPB) (27°C) flow rates of 2.3 and 1.2 L/min/m 2, and 30 minutes post-CPB. Anesthesia consisted of fentanyl and midazolam; pH management was a-stat, and mean arterial pressure was maintained at 50 to 70 mmHg throughout CPB. Measurements and Main Results: In the context of an unchanged mean arterial pressure, the pump flow did not affect cerebral blood flow or metabolic rate during hypothermic CPB. Systemic venous oxygen saturation was also maintained during reduced flow at 27°C. Hemodilution during hypothermic CPB maintained cerebral blood flow at prebypass levels. In the postbypass period, persistent hemodilution resulted in an elevated cerebral blood flow. Conclusions: Brain oxygenation is well maintained at lower than conventional pump flow levels during CPB. There may be practical advantages to reduced flows during hypothermia, and flow reductions do not appear to adversely affect cerebral blood flow or metabolism.

The Relationship Between Cerebral Blood Flow and Transcranial Doppler Blood Flow Velocity During Hypothermic Cardiopulmonary Bypass in Adults

The Relationship Between Cerebral Blood Flow and Transcranial Doppler Blood Flow Velocity During Hypothermic Cardiopulmonary Bypass in Adults

The Relationship Between Cerebral Blood Flow and Transcranial Doppler Blood Flow Velocity During Hypothermic Cardiopulmonary Bypass in Adults

A noninvasive, simple, and continuous method to assess cerebral perfusion during cardiopulmonary bypass (CPB) could help prevent cerebral ischemia. Transcranial Doppler sonography (TCD) allows a noninvasive, on-line measurement of blood flow velocity in cerebral arteries. The correlation of TCD-estimated and actual cerebral blood flow (CBF) has not been well studied during CPB. We determined the correlation of middle cerebral artery (MCA) mean velocity and CBF determined by the Kety-Schmidt method during nonbypass and two hypothermic bypass flow conditions. Sixteen patients undergoing hypothermic (27 degrees C) CPB for coronary artery bypass grafting and/or valve replacement surgery were enrolled in the study. We were able to determine MCA velocity in only 12 patients. We determined CBF and MCA velocity in each patient during four 15-min study periods: 1) prebypass after sternotomy before aortic cannulation; 2) hypothermic (27 degrees C) CPB with 1.2 L.min-1.m-2 pump flow; 3) hypothermic CPB with 2.4 L.min-1.m-2 pump flow, and 4) 30 min after weaning from CPB. There was no difference in the mean arterial pressure between the two CPB pump blood flows. The pooled change in MCA velocity and CBF as percentage of baseline (prebypass) for all patients and at all time points had a correlation of 0.33 (r). A decrease or increase in MCA velocity did not necessarily indicate a corresponding decrease or increase in CBF. This technology may be of limited usefulness during the circulatory condition of hypothermic, nonpulsatile CPB.

Cerebral hyperthermia during cardiopulmonary bypass in adults

Accepted for publication June 7, 1995 In this report, we document that cerebral hyperthermia occurs regularly during rewarming from hypothermic cardiopulmonary bypass (CPB). These high brain temperatures are not adequately reflected by nasopharyngeal (NP) temperature and may contribute to neurologic morbidity. Stroke and neurocognitive injury remain significant components of perioperative morbidity associated with cardiac surgery. Hypothermic CPB is used in part for its cerebral protective effects. Recent reports, however, have indicated that the rewarming phase of hypothermic CPB is associated with a significant incidence of decreased cerebral venous oxygen saturation (Sjvo2; 50%). 1,2 Sjvo2 is thought to be a general index of the adequacy of the matching of cerebral oxygen supply with demand.

A Comparison of Flow Gradients across Disposable Arterial Perfusion Cannulas

Five-hundred members of The Society of Thoracic Surgeons were canvassed to discover which cannulas are currently used for open-heart surgical procedures in adults; 120 surgeons responded. The mean arterial line pressure produced by 29 disposable arterial perfusion cannulas (size range, 16F to 30F) at flow rates of 1 to 5 liters per minute was compared. A roller pump with perfusion tubing 95 mm (0.75 inch) in diameter was used with water as the test solution. Line pressures in these cannulas ranged from 22.4 ± 2.30 (standard deviation) to 271.0 ± 6.60 mm Hg at 5 L/min. Four 24F cannulas had gradients of less than 55 mm Hg at a flow rate of 5 L/min, and 6 cannulas—4 of which were 22F and 2, 24F—had gradients higher than 150 mm Hg at 5 L/min. A number of cannulas kinked easily, and these showed marked increases in line pressure. The following results were obtained from this study: (1) a wide range of line pressures was observed in disposable arterial perfusion cannulas currently in clinical use; (2) some cannulas currently used for cardiopulmonary bypass in adults generated excessive line pressure; and (3) both material and design affect function, with some designs being safer than others. Cardiac surgeons should base the choice of an arterial perfusion cannula on the best performance and safest design available to avoid cannula-related problems at operation.