Background
Overview
Cardiopulmonary bypass (CPB) is a special method that briefly assumes the function of the heart and lungs during surgery to offer a bloodless, sufficient surgical area while ensuring a sustained circulation of blood and oxygen contents to the rest of the body. Using advanced techniques, the medical device continues with the blood circulation and gaseous exchange and subsequently restores normal processes once the surgical procedure is completed. With the continuous developments in the medical field, the cardiopulmonary bypass technology also expands its scope of application not only in cardiothoracic surgeries, which can correct rheumatic heart disease, congenital heart disease, and macroangiopathy, and other surgical applications but also in tumor surgery and heart transplant (Alkan-Bozkaya et al. 879-84). This surgical intervention method has become important life support in clinical surgery technology. In the cardiopulmonary bypass technique, the blood perfusion involves two mechanisms: non-pulsatile perfusion (NP) and pulsatile perfusion (PP). For over half a century, scholars have explored different perfusion mechanisms based on the pros and cons of mixed results. The advantage of pulsatile perfusion is that the blood flow generated is closer to the pulsatile blood flow from the ventricles (Jung et al. 1118–1123). It can significantly increase blood perfusion into vital organs, including the brain, heart, liver, and kidney. Also, this method can reduce systemic inflammatory responses and postoperative mortality. After the recovery of vital organs, patients’ challenges, and recovery rates often get widespread attention from cardiac surgery specialists (Jung et al. 1118–1123). However, for the evaluation of the effectiveness of pulsatile perfusion, the clinical tool lacks simple, objective, and practical evaluations for indicators and constraints.
For the past decades, some scholars have carried out important studies on the theory of pulse perfusion, the objective of pulse diagnosis, and clinical diagnosis research, and they realized great achievements (Jung et al. 1118–1123). With the rapid development in computer science and technology and medical science, the mutual integration of these developments with the focus on the pulse practicality has led to a revolutionary breakthrough (Jung et al. 1118–1123). Many scholars use the pulse diagram for the pulse formation mechanism, human physiology, and pathological phenomena (Jung et al. 1118–1123). The modern pulse diagnosis technology in clinical areas, such as clinical diagnosis, health assessment, efficacy evaluation, and treatment of diseases, has also been widely popular.
Method
For the literature review, relevant academic journals related to the study were searched to identify major studies, guidelines, and perceived limits of perinatal training from 2008 to 2013. The research databases searched were J-Stage, Artificial Organs, Sage, and Biomechanics. The study included an evaluation of the two CPB methods of various mechanisms, the benefits, and the outcomes after surgery. These experiments accounted for patients’ age, height, weight, and body surface area (BSA).
Literature Review
Cardiopulmonary bypass surgery and heart surgery have become increasingly popular and advance. However, due to the blood flow caused by cardiopulmonary bypass is non-pulsatile perfusion (NP) and physiological fluctuations compared to perfusion (PP), the outcomes can cause many adverse consequences. Furthermore, the field of cardiac surgery continually develops, and the study of the pulsatile perfusion (PP) has attracted more and more attention from scholars (Wang et al., “Impact of the Postpump” 277-81).
Vital Organ Recovery
Some researchers evaluated the vital organ recovery and thyroid hormone homeostasis when patients undergo cardiopulmonary bypass surgery to analyze which perfusion is better for patients (Alkan-Bozkaya et al. 879-84). During these studies, researchers randomly chose two types of modes, and they are non-pulsatile perfusion (NP) and pulsatile perfusion (PP). Two hundred and eighty-nine patients were chosen to undergo open-heart surgery to provide data for the study. After the surgery, patients’ enzyme level, blood counts, or drainage amounts between two groups were evaluated (Alkan-Bozkaya et al. 879-84). The key finding of the study was that the PP group required significantly less postoperative inotropic support than group NP. Moreover, the benefits of the PP group included shorter duration of intubation and shorter length of stay in the ICU (Alkan-Bozkaya et al. 879-84). This finding supported the observation that pulsatile perfusion results in improved vital organ recovery and patient outcomes (Alkan-Bozkaya et al. 884). Notably, the concentration of plasma of thyroid hormone quickly declines steadily following the CPB, but the defensive effect is derived from the pulsatile perfusion relative to the nonpulsatile perfusion (Alkan-Bozkaya et al. 879-84). It was also demonstrated that pulsatile perfusion had more favorable effects on cardiac and kidney functions than the non-pulsatile technique (Mohammadzadeh et al. 158–162).
Effect of Different Perfusion Patterns on Renal Blood Flow
The role of the kidney mainly involves the elimination of metabolic toxic waste products and alien substances from the plasma to maintain the body’s dynamic balance of the environment. The physiological function is reflected in three aspects: the generation of urine, regulation of electrolytes, acid-base balance, and regulation of endocrine function (Alkan et al., “Effects of Pulsatile” 530-535). Studies have shown that pulse perfusion can increase renal blood flow, thereby increasing the oxygen supply and helping to relieve renal vasoconstriction (Alkan et al., “Benefits of Pulsatile” 651-654). In this study, researchers evaluated 215 consecutive children who underwent open-heart surgery for congenital heart disease (Alkan et al., “Benefits of Pulsatile” 651-654). The children were enrolled, randomized, and classified into two groups of PP and NP. All patients got similar “medical procedures and post-care and vital complications and clinical outcomes were recorded” (Alkan et al., “Benefits of Pulsatile” 651-654). The result of the experiment suggested that at the onset of the recovery period following the surgery the PP group had significantly restored the health of the kidney and the main vein system. It was shown that pulsatile flow had better effects on patient outcomes (Alkan et al., “Benefits of Pulsatile” 651-654).
Some researchers studied coronary bypass grafting or aortic valve replacement to analyze how pulse perfusion affects patients’ clinical outcomes after CPB surgery. A study by Liu and Han mainly focused on renal functions in critically ill patients, in-hospital stay, and mortality rate (1192–1198). However, CPB surgery is still considered as a complex, high-risk cardiac surgery in patients. Therefore, it needs further study. In this study, the authors assessed the influence of the pediatric patients with CPB surgery and compared PP with NP during CPB on cytokines, hemolysis, and renal function (Liu and Han 1192–1198). The result of the experiment showed that PP in the CPB surgery can reduce the inflammatory rate in pediatric patients, and it can be successfully and easily performed in the pediatric CPB (Liu and Han 1192–1198).
Blood Flow Degree Under Two Different Perfusions
Studies have also analyzed variations of the blood flow under non-pulsatile and pulsatile influences. In a study by Jung et al., a mock system was used to compare the hemodynamic energy under the PP and NP groups (1118–1123). Jung et al. based their study on the notable role of the centrifugal pump in pulsatile perfusion (1118–1123). The pump runs on resistance attributes using rotation to generate resistance and various flow rates. It must also provide optimal rotational speed to avoid a potential backflow. A high-resistance centrifugal pump was associated with declined flow rates, while high blood cell trauma could cause elevated resistance during rotation. On the other hand, the roller pump was used to control resistance (Jung et al. 1118). Thus, patients could be pumped with blood at a suitable rate through hollow oxygenators using centrifugal pumps. Such pumps are preferred for their lower speed of rotation, and they reduce hemolysis. It is important for clinical cardiopulmonary bypass because of smaller size, safety, and stability about mobility and tubing and lower priming capacity. Thus, the pump is preferred because of sustained cardiopulmonary management. This study focused on atherosclerosis patients because they gradually develop narrower vessel lumens over time. It involved a comparison between the PP and NP flow of the hemodynamic energy, and the results showed that PP flow had a better effect on hemodynamic energy than NP flow in the prevention of stenosis (Jung et al. 1118–1123). After assessing various degrees of hemodynamic energy in diameter and stenosis in PP and NP flow in a simulated system mode, the main study results suggested that under the PP situation, hemodynamic energy could maintain more than five percent. Therefore, the results demonstrated that PP flow had a better effect on atherosclerosis patients than NP flow in the prevention of stenosis lesions (Jung et al. 1118).
Oxygen Carrier Experiment with PP and NP
Most pediatric patients undergoing cardiac surgery have to rely on “extracorporeal membrane oxygenation (ECMO) to strengthen the heart and respiratory support in case of heart failure” (Vasavada et al. E101). Traditionally, this technique used to work under the condition of non-pulsatile perfusion. However, current studies show that pulsatile perfusion patients can have better outcomes during the ECMO support for heart failure (Vasavada et al. E101–E107). Ten newborn babies with congenital heart disease were tested. All surgeries involved a new ECMO pump with the PP. The finding showed that the pulse ECMO supports patients’ lactate recovery faster than the NP condition. Additionally, it reduced all the recovery durations (Agati et al. S87). The intensive care management of the PP group is much more managed than the NP condition. The acute renal patients’ hemofiltration rate under the PP condition is much better than the NP group. Furthermore, this experiment also demonstrated that the pulsatile perfusion ECMO was a reliable and safe method for cardiac surgery support (Agati et al. S87).
Lactic acid is produced by the reduction of pyruvate under the action of lactate dehydrogenase and is the final product of anaerobic glycolysis. The glucose in the body is decomposed into pyruvate by anoxic oxidation. Pyruvate undergoes a series of dehydrogenase to form lactic acid. This process is called anaerobic decomposition of sugar, also known as glycolysis. Its main physiological significance is that it helps the body in the anaerobic or anoxic state to obtain energy, and as an effective measure, it also assists the body in the stress state of energy to meet the physiological needs of the body using the generated energy (Vasavada et al. E101). However, hypoxia leads to excessive glycolysis perhaps due to excessive lactic acid, causing lactic acidosis. Lactic acid increases acidosis so that myocardial contractility decreases systolic blood pressure, peripheral vascular dilatation, reduces oxidative phosphorylation levels, and affects myocardial tissue after sugar utilization, thereby increasing the risk of myocardial injury and arrhythmia. The level of lactic acid during cardiopulmonary bypass reflects glucose metabolism, tissue oxygen supply, and microcirculation, which can be used as biochemical markers for tissue perfusion and oxygen deficiency (Vasavada et al. E101).
Some studies tested the oxygen hemodynamic energy under pulsatile (PP) and non-pulsatile flow. One study demonstrated the use of neonatal extracorporeal life support models to indicate the oxygen flow of the PP and NP (Vasavada et al. E101). The other study evaluated an oxygen carrier in two pediatric polymethyl pentene membranes with the PP and NP (Qiu et al. 229). Researchers also tested polymethyl pentene hollow-fiber oxygenators to evaluate the pulsatile and non-pulsatile conditions and determine the best one. Although this is a new technique involving Quadrox-iD Pediatric PMP membrane oxygenator for clinical testing in America, it is already widely used in Europe. The study results showed that all the oxygenators sufficiently performed well when pressure was low and in hemodynamic energy preservation for the two polymethyl pentene (PMP) hollow-fiber membrane oxygenators: the Medos HILITE 2400 LT and the Maquet Quadrox-iD Pediatric (Qiu et al. 229). In addition, no significant variances were observed between pre-oxygenators and post-oxygenators for mean pressure, energy equivalent perfusion pressure, and the aggregate hemodynamic energy. In fact, when the process was in pulsatile mode, the Medos HILITE 2400 LT had a higher percentage of more hemodynamic energy across the oxygenator, and it was concluded that the two oxygenators were appropriate for pediatric ECLS therapy under both non-pulsatile and pulsatile perfusion (Qiu et al. 229). Therefore, these devices could be used to provide the highest pulsate energy in the extracorporeal circuit (Qiu et al. 229). Therefore, in this experiment, it was established that at different flow rates, such as pressure drop and blood flow energy transfer, Quadrox-iD had excellent performance in terms of blood pressure kinetic energy retention (Qiu et al. 229). Comparatively, oxygenators were more suitable for PP, and PP plays an important role in the delivery of oxygen in the body via blood circulation (Qiu et al. 229).
There was also a study to compare pumps and oxygenators in infants with PP and NP (Haines et al. 993–1001). Haines et al. based their study on evidence that supported pulsate perfusion during CPB (993). Thus, it was imperative to assess the outcome of circuit elements on the quality of pulsatility provided via the circuit (Haines et al. 993–1001). The study used a neonatal extracorporeal life support model to compare the quality of perfusion delivered by two oxygenator fiber membranes and silicone membrane. Since during the surgery, the body has insufficient oxygen flow in the blood, severe postoperative complications can occur, for example, patients may even develop respiratory tract infection or nerve damage (Vasavada et al. E101–E107). Therefore, this study aimed to demonstrate the best perfusion method that could deliver more oxygen between the two membranes and was suitable for patients undergoing cardiopulmonary bypass surgery. The study attempted to show whether PP or NP had favorable outcomes in improving vital organs based on different oxygenator flow rates. The results of the experiment suggested that PP had a better transmission of hemodynamic energy through the two membranes under lower pressure (Vasavada et al. E101–E107).
An experiment by Haines et al. compared oxygenators used for infant cardiopulmonary bypass (CPB) models with pulsatile and non-pulsatile perfusion (993–1001). This experiment studied two blood pumps used to delivered oxygen throughout via body blood circulation, and the researchers investigated the whole circuit to distinguish PP and NP’s different effects on the quality of the delivered oxygen. Major factors, such as deep hypothermic cardiac arrest, ischemia-reperfusion, hypoperfusion, non-pulsatile perfusion, and systemic inflammatory response, were often important in pediatric CPB and procedures designed to help patients to overcome congenital heart defects of organ damage and injuries to patients during critical stages of patient recovery. This study evaluated pulsatility produced by different kinds of blood pumps through two oxygenators pressure drops and oxygen delivered to the body through blood circulation with different oxygenators energy equivalent pressure and total hemodynamic energy (Haines et al. 993–1001). It was demonstrated that the PP model could deliver more oxygen to the body circulation and, hence, it proved that the PP was better than NP in the infant CPB surgery (Haines et al. 993). Additionally, Haines et al. observed that cautious selection of every circuit element depending on specific clinical cases and parts was important to attain the optimal quality of pulsatility (993–1001).
Effect of Different Perfusion Modes on Nitric Oxide
Nitric oxide (NO) has been recognized for its role in controlling contractility and heart rate, reducing cardiac remodeling after infarction, and positive protective effect of ischemic preconditioning and post-conditioning (Rastaldo et al. 993). Nitric oxide is a kind of a free radical gas molecule with an active property. Its main source is endothelial cells. In recent years, the role of nitric oxide in the cardiovascular system has received extensive attention and is an endogenous relaxing factor that is physiologically moderated independently in the blood vessels, myocardium, and endocardium. Studies found that vascular endothelial dysfunction and abnormal NO content in many diseases often appear. Microcirculatory dysfunction may occur with a condition that accompanies this phenomenon (Rastaldo et al. 779–793). The experimental results showed that the two groups of perfusion models after 30 minutes of cardiopulmonary bypass shutdown led to a rapid increase in the NO content and six hours after surgery, it dropped to preoperative levels. It was speculated that the outcome could be due to the body’s compensatory anti-inflammatory response. Notably, the body produced a large number of tumor necrosis factor, interleukin, and other inflammatory mediators during the cardiopulmonary bypass. Moreover, NO can be induced by these inflammatory mediators and, thus, the synthesis and release of NO increases to match the changes (Rastaldo et al. 779). NO may reduce vascular permeability by changing the intracellular cGMP level, dilating the ischemic region of blood vessels, improving microcirculation function, and reducing tissue damages.
The results showed that there was no significant difference in the content of NO between pulsatile perfusion group and non-pulsatile perfusion group at different time points (P> 0.05). The influence of different perfusion modes on NO in this experiment has not been determined yet (P <0.05), suggesting that the content of NO in pulsatile perfusion group may be related to the storage period, individual differences of patients, and the difference of nitric oxide characteristics and local concentration (Rastaldo et al. 779). Actions of NO on the heart emanate from vascular, endocardial, endothelial, and neuronal and inducible syntheses (Rastaldo et al. 779). It was specifically observed that endothelial synthase had the major function during the basal management of contractility while the cardiodepression in septic shock was the responsibility of the inducible isoform (Rastaldo et al. 779).
Effects of Different Perfusion Modes on Endothelin
Sezai et al. recognized that research on pulsatile and nonpulsatile perfusion was abundant, but they further observed that researchers have not sufficiently identified the most efficient one (708-13). In this study, pulsatile cardiopulmonary bypass (CPB) was evaluated about the outcomes on “cytokines, endothelin, catecholamine, and pulmonary and renal functions” (Sezai et al. 708). Endothelin (ET) is the most important and long-acting endothelin-like factor isolated and purified from endothelial cells. It is widely distributed in the nervous system, endocrine system, and circulatory system. ET-1, ET-2, and ET-3 are the three isoforms of endothelin-1, which are composed of 21 amino acids and are encoded by different genes. Human vascular endothelial cells only produce and release ET-1, no other isomeric forms. ET-1 had a strong contraction of blood vessels. Studies show the application of fluorescent pigment method to observe the vascular diameter and blood flow velocity, ET-1 found in a dose-dependent contraction of blood vessels, and lower blood flow velocity (Sezai et al. 708-13). It has been reported that plasma ET-1 levels in patients with rheumatic valve heart disease undergoing CPB continued to rise and peak at the end of CPB compared with preoperative and healthy plasma ET-1 (Sezai et al. 708-13). This suggests that a higher level of ET-1 causing endothelial cell damage may be involved in secondary pulmonary hypertension and circulatory disorders and other related diseases (Sezai et al. 708-13).
The levels of ET-1 in the non-pulsed perfusion group were higher than those in the preoperative and postoperative six hours after the operation, suggesting that non-pulsatile perfusion may influence the organ and tissue of the organism in ischemia, hypoxia, or stress state, causing vascular endothelial cell injury and lead to increased peripheral resistance and microcirculation dysfunction. There was no significant difference in the content of ET-1 between preoperative and postoperative 30 minutes after pulsatile perfusion, which indicated that the intraoperative perfusion pattern was beneficial to alleviate vascular endothelial cell injury, decrease peripheral vascular resistance, and maintain microcirculation function (Sezai et al. 708). Overall, Sezai et al. concluded that the capabilities to slow down influences on the role of cytokine, edema found in the pulmonary alveoli, and the endothelial injury were demonstrated alongside the supportive outcomes on the level of catecholamine, renal activities, and peripheral circulation (708-13).
Effects of Different Perfusion Modes on Cytokines
In the process of cardiopulmonary bypass, the contact of blood with non-physiological channels, organ ischemia-reperfusion injury, and changes in the body temperature and non-pulsating low perfusion pressure will cause a series of cell defense system activation. Moreover, it can release of inflammatory mediators and lead to systemic inflammatory response syndrome (SIRS) (Sezai et al. 708-13). SIRS will lead to organ damage, pathological manifestations of severity in patients with lung, kidney, heart, and central nervous system disorders, coagulation disorders, hemolysis, and fever among others. Cytokines are small-molecule polypeptides or proteins produced by various cells in the body, and their production is short-term and is regulated and controlled strictly. It plays an important role in the immune regulation and inflammation of the body significantly, including tumor necrosis factor (TNF), interleukin, interferon, transforming growth factor, and chemokines, which release the tumor necrosis factor, interleukin (Sezai et al. 708-13).
The results showed that IL-6 levels in the non-pulsatile perfusion group were significantly higher than those in the T1 and T3 time points were (P <0.05). The levels of IL-6 in the pulsatile perfusion group were significantly higher than those in the T1 and T3 time points were (P <0.05). There was no significant difference in IL-6 level between the two groups at every point (P> 0.05). The trend of TNF-α content in the two groups was basically the same. There was no significant difference in the TNF-α level between the two groups before and after the operation, suggesting that pulsatile perfusion may be beneficial in reducing a systemic inflammatory response (Sezai et al. 708-13).
Improvement of Effect of Pulsatile Perfusion
Some studies have focused on the PediVASTM centrifugal pump kinetic energy to analyze and seek optimal settings for pulsatile flow to obtain better pulsation energy and minimal pulsating flow (Wang et al., “Effects of the Pulsatile” 271-6). Unfortunately, many centrifugal pumps are known for only NP flow (Wang et al., “Effects of the Pulsatile” 271). Centrifugal pumps generate only a minimal number of the pulsating flow. Thus, this study aimed to evaluate various pulsating flow settings of centrifugal pumps for better performance and the minimum return flow (Wang et al., “Effects of the Pulsatile” 271-6). The results showed that the differences that affected pulsatility emanated from the speed of rotation and flow width, but influences of the pump were minimal (Wang et al., “Effects of the Pulsatile” 271). The central force should overcome the resistance downstream of the pump to avoid a potential backflow (Wang et al., “Effects of the Pulsatile” 271). Therefore, the control system has a significant effect on “the quality of the pulsating flow” (Wang et al., “Effects of the Pulsatile” 271). Further, it was observed that the factor of the rotational speed variation ratio could inevitably enhance pulsatility with additional rotational speeds, but further studies would be necessary to elevate the pulsatile flow attributes of the centrifugal pump (Wang et al., “Effects of the Pulsatile” 271).
In France, researchers concentrated their efforts to find a simple and relatively affordable pediatric pulsating roller blood pump for the CPB surgery. The pump might be used as life support and left or right ventricular assist system for the CPB surgery. Evidence shows benefits associated with the PP during acute and chronic life support of pediatric and adult patients undergoing CPB surgery. The study suggested that PP could efficiently lead to a shorter hospital stay and let vital organs to recover faster (Alkan et al., “Benefits of Pulsatile” 651-654). The result of the experiment demonstrated that PP does not only maintain the regional body flow but also successfully provides blood flow for the brain and the kidney. PP is better than NP because it can also minimize the vital organ damage and eliminate the side effects of CPB procedures (Alkan et al., “Benefits of Pulsatile” 651-654).
Baraki et al. evaluated the effect of pulsatile perfusion on recovery following coronary bypass grafting or aortic valve replacement (AVR) (166). The physician selected the PP and NPP pulsatile perfusion. Based on the preoperative variables, the possibility of a patient getting NPP or PP was determined. The results indicated that PP was superior to NPP, and its favorable outcomes increased as logistic EuroSCORE increased (Baraki et al. 166). The findings also demonstrated that physicians had significant influences on the length of stay at the ICU, ventilation period, and transfusion supplies. Pulsatile perfusion failed to affect renal activity, perioperative result factors, and deaths, but it led to reduced length of hospital stay, particularly in critically sick individuals (Baraki et al. 166).
The Advantages and Clinical Outcome of Pulsatile Perfusion
There has been much debate about the merits of these practices for many decades (Alkan et al., “Effects of Pulsatile” 530-535). The objective of such a thorough study is to achieve the optimal standard of excellence in the CPB interventions, ultimately curtailing illnesses and deaths of patients (Alkan et al., “Effects of Pulsatile” 530-535). Presently, pulsatile perfusion studies continue to show promising outcomes related to a significant increase in “vital organ blood flow and microcirculation of infant patients and models of surgical and postoperative findings” (Alkan et al., “Effects of Pulsatile” 530-535). Besides, the use of pulse perfusion is seen as having a positive influence on the recovery process by reducing the “systemic inflammatory response syndrome, inotropic support, intubation duration and duration of hospitalization” (Alkan et al., “Effects of Pulsatile” 530).
According to Ji and Ăśndar, for more than 50 years, confusion still exists on the advantages of the pulsatile and nonpulsatile perfusion when used in the cardiopulmonary bypass (CPB) (357-361). Initially, nonpulsatile perfusion was considered the most common perfusion method used in CPB relative to the drawbacks of the pulsatile pump. That is, the pump could not produce sufficient pulsatility, was complex to use, and had higher chances of hemolysis. As such, nonpulsatile perfusion appeared to be the best technique for individuals who used it and patients who had heart conditions because it saved their lives. Nonetheless, it was also imperative to evaluate the number of patients that lost their lives because of the use of nonpulsatile perfusion (suboptimal method) and the extra medical resources needed to operate and reduce adverse outcomes on patients (Ji and Ăśndar 357-361). Thus, there was a need to change the status quo.
Today, however, the development in biomedical science has transformed CPB through many safe, straightforward, solid, and relatively affordable pulsatile pumps that are simple to set up and use. With the advanced machines for the heart and lung, “a single button” is utilized to substitute the two perfusion modes amid CPB (Ji and Ăśndar 357-361). It is possible to activate some models of pulsatile pumps using an electrocardiogram to provide pulsatility in both instances of cardiac arrest and regular heart functioning (Ji and Ăśndar 357-361). In the past few decades, research focused on pulsatile perfusion during CPB done in clinical settings using patients and experiments involving animals has demonstrated that pulsatile perfusion is more advantageous to patients compared with nonpulsatile perfusion (Ji and Ăśndar 357-361). While it is true that several findings have not successfully shown the distinction between NP and NPP and their related failures, such inferences could have been influenced by multiple factors. These factors may include poor comprehension of the ideal measure of the pressure-flow waveforms, drawbacks in study designs, or poor choices of elements of the extracorporeal circuit, such as membrane oxygenators and pumps, without applying any scientific process (Ji and Ăśndar 357-361).
Some advantages of PP and NPP have been noted in pediatric patients (Ji and Ündar 357-361). Alkan et al. used 50 patients undergoing CPB surgery to demonstrate clinical outcomes of NP and NPP (“Effects of Pulsatile” 530-535). They separated those patients into the PP group (PP, n=25) and NP group (NP, n=25). In their experiment, Alkan et al. demonstrated a significant reduction in muscle strength, tracheal intubation, ICU stay, and the length of hospital stay in the PP group (“Effects of Pulsatile” 530-535). Furthermore, the study also showed a better recovery of the myocardial, lung, and renal function (Alkan et al., “Effects of Pulsatile” 530-535).
During the first half of the twenty-first century, physiologists used a pump that produced intermittent blood flow during experiments in which animals were exposed to organ and tissue perfusion. For this purpose, many piston and diaphragm pumps were invented and accepted to support the natural flow of the heart (Ji and Ăśndar 357-361). In some mainstream views, there is no doubt that pulsatile blood flow is beneficial, and the primary advantages can be summarized as follow. First, natural blood flow is the best. Second, pulsatile perfusion increases fluid flow as the formation of lymphatic flow also increases. Thirdly, tissue metabolic rate, and waste lead to exclusion. Finally, energy transfer from the pump to the tissue is more efficient.
Some research studies used the model to find out the advantages of pulse flow in pediatric CPB. In such experiments, researchers not only study the experimental data but also collected additional clinical data. The collected experimental and clinical data are directly used for comparisons between perfusion patterns. When newborn babies under CPB surgery, they are exposed to possible damages to their vital organs. In this study, the study focused only on pulsatile and non-pulsatile flow during pediatric CPB surgery. Also, they showed past results, which included details about the choice of components of the CPB circuit, pulsatile flow, and other clinical findings (Ăśndar et al. 35-9). Some studies have demonstrated that pulse flow significantly minimizes the adverse effects of CPB procedures and has no known limitations compared to non-pulsatile flow (Ăśndar et al. 35-9). Additionally, regular pulse flow studies have indicated a significant benefit of pulse perfusion in pediatric patients with heart disease and have no adverse effects (Ăśndar et al. 35-9).
Most patients who suffer from diffused and extensive disease still opt for coronary artery bypass grafting treatment (Serraino et al. 1121-1129). Some findings have proved that pulsatile perfusion cardiopulmonary bypass is effective in protecting vital organ functions and reducing endothelial activation (Serraino et al. 1121-1129). Serrano et al. strived to assess whether the use of an intra-aortic balloon pump during cardiac intervention improved organ function and reduced endothelial activation in patients undergoing coronary artery bypass grafting (1121-1129). The main purpose of this study was to evaluate hemodynamic response, transaminase, amylase, and renal function. Findings indicated that patients who stayed in ICU for 48 hours had better results, and pulsatile flow could protect liver function and reduce kidney failure (Serraino et al. 1121-1129). Damages to vital organs, such as the liver, and the kidney, were the most common complications of CPB. Besides, patients undergoing pulsatile perfusion indicated a lower consumption of coagulation and fibrinolysis. This result suggested a significant reduction in postoperative infection rates after the surgery (Serraino et al. 1121-1129).
Furthermore, some studies also claim that during the cardiopulmonary bypass surgery, pulsatile flow can improve cerebral blood flow (W. Wang et al. 874–878). The mortality rate has significantly decreased among infants undergoing pediatric cardiac surgery in recent years mainly due to great improvements in techniques and device developments. However, CPB may lead to complications in vital organs. Some studies have reported that pulsatile flows compared with the non-pulsatile flow have limited compliance. Moreover, the PP patterns show that patients do not have brain metabolism effects following surgery (W. Wang et al. 874–878). In the study, 30 infants with mild hypothermic were randomly chosen for cardiopulmonary bypass surgery. Fifteen of them were in the pulsatile group (P, n=15) and the rest were in the non-pulsatile group (NP, n=15). The study then evaluated the effect of blood flow between the two groups while applying the aortic clamping (W. Wang et al. 874–878). The result of this experiment suggested that PP significantly increased cerebral blood flow and reduced cerebrovascular resistance at the early phase of recovery after surgery compared with NP (W. Wang et al. 874–878).
CPB has greatly improved prognosis and mortality in pediatric cardiac surgery for congenital heart diseases. Increasingly, there is a demand to address the paradoxical surge in adverse neurological outcomes in surgical survivors. Evidence suggests that pulsatile perfusion can improve cerebral oxygen saturation and blood flow during pediatric cardiopulmonary bypass surgery (Su et al. 181–185). This study monitored brain near-infrared spectroscopy and a transcranial Doppler ultrasound to analyze whether PP or NP had effects on the brain. After an assessment of more than 100 young patients, it was discovered that patients undergoing PP had a lower oxygen saturation baseline than NP patients, which significantly decreased by 12% to 40% within 60 minutes after the procedure. The result suggested PP might improve postoperative neurodevelopmental outcomes. Also, all patients after surgery were ready for discharge and had no clinical seizures, stroke, or neurological sequelae (Su et al. 181–185).
Conclusion
Evidence suggests that researchers have already accomplished so much with regard to the pediatric cardiopulmonary bypass procedure. However, they also need to conduct further research to eliminate other pitfalls that occur during and after congenital heart surgery. Compared with the non-pulsatile perfusion, pulsatile perfusion had more advantages. For instance, pediatric patients have better outcomes after CPB surgery. Additionally, pediatric patients have shorter stays in ICU and hospitals. The pulse energy used allows physicians to select accurate quantification of mass circuit components. In this procedure, pediatric patients can obtain more pulsation energy with less deterrence. Finally, evidence shows multiple benefits associated with the pulsatile perfusion for patients undergoing CPB surgery. Future research will strive to expand areas for further studies.
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