Nonpulsatile Perfusion Research Articles

Abstract 4138558: The effect of pulsatile vs. non-pulsatile perfusion on hospital stay, ICU stay, and intubation time in patients undergoing cardiopulmonary bypass: A meta-analysis randomized controlled trials.

Background: Pulsatile perfusion is a developing technique that attempts to mimic the natural pulsatile flow of blood during cardiopulmonary bypass (CBP). Purpose: Our meta-analysis was done to evaluate the effects of pulsatile perfusion in CPB compared to non-pulsatile on hospital stay, ICU stay, and intubation time. Methods: Randomized control trials that evaluated the implementation of pulsatile perfusion during CPB were identified by a literature search of the following databases (PubMed, Web of Science, Scopus, Central, and Embase) up to February 2024. Results: Our search yielded 33 trials with 3174 patients, the analysis showed that pulsatile perfusion led to a significant decrease in hospital stay [MD = -1.38, 95% CI (-2.51, -0.25), P = 0.016], ICU stay [MD = -0.47, 95% CI (-0.82, -0.13), P = 0.007], intubation time [MD = -3.73, 95% CI (-5.42, -2.04), P < 0.001]. However, no significant difference between the two regimens was detected in the adult subgroup when we performed sungroup analysis based on the age for hospital stay and ICU stay outcomes [MD = -0.31, 95% CI (-0.95, 0.33), P = 0.334] and [MD = -3.73, 95% CI (-5.42, -2.04), P < 0.001] respectively. Conclusion: Pulsatile perfusion showed positive effects on hospital stay, ICU stay, and intubation time. However, there was no difference between the two methods on hospital and ICU stay in the adult’s subgroup. Also, the outcomes showed significant heterogeneity, which requires more robust RCTs to be conducted to increase the quality and the certainty of evidence.

How to Design a Study Comparing Pulsatile and Nonpulsatile Perfusion During Cardiopulmonary Bypass?

How to Design a Study Comparing Pulsatile and Nonpulsatile Perfusion During Cardiopulmonary Bypass?

NEUROLOGIC IMPAIRMENT IN PATIENTS WITH EXTRACORPOREAL CARDIOPULMONARY RESUSCITATION SUPPORT: CLINICAL FEATURES AND LONG-TERM OUTCOMES.

Introduction: The present study aimed to explore the clinical features and long-term outcomes associated with neurologic impairment in patients with cardiac arrest (CA) who received extracorporeal cardiopulmonary resuscitation (ECPR). Methods: A total of 37 adult CA patients who underwent venoarterial extracorporeal membrane oxygenation and were admitted to our department between January 2015 and February 2022 were divided according to neurologic impairment. Baseline and CPR- and ECMO-related characteristics were compared between the two groups. Long-term neurologic outcomes were collected via telephone follow-ups. Results: Twenty-four (64.9%) ECPR-supported patients developed neurologic impairments. The two groups differed significantly in median age (P = 0.026), proportion of intra-aortic balloon pump (IABP) support (P = 0.011), proportion of continuous renal replacement therapy (P = 0.025), and median serum creatinine (Cr) level (P = 0.012) pre-ECMO. The 28-day mortality (P = 0.001), hospital mortality (P = 0.003), median duration from CA to restoration of spontaneous circulation (P = 0.029), proportion of patients with nonpulsatile perfusion (NP) >12 hours (P = 0.040), and median ECMO duration (P = 0.047) were higher in the neurologic impairment group. In contrast, the group without neurologic impairment exhibited a longer median intensive care unit length of stay (P = 0.047), longer median hospital LOS (P = 0.031), and more successful ECMO weaning (P = 0.049). Moreover, NP >12 hours combined with IABP support (odds ratio [OR], 14.769; 95% confidence interval [CI], 1.417~153.889; P = 0.024) and serum Cr level (OR, 1.028; 95% CI, 1.001~1.056; P = 0.043) were independent risk factors for neurologic impairment. Furthermore, neurologic impairment was associated with significantly worse 90-day survival (hazards ratio, 4.218; 95% CI, 1.745~10.2; P = 0.0014). Conclusions: The incidence of neurologic impairment was higher in patients who received ECPR and was closely related to 28-day mortality and discharge survival. NP >12 hours combined with IABP support and serum Cr levels were independent risk factors for neurologic impairments in ECPR-supported patients. Neurologic impairment significantly adversely affected the long-term outcomes of ECPR-supported patients after discharge.

A Randomized Clinical Trial of Perfusion Modalities in Pediatric Congenital Heart Surgery Patients

BackgroundThe objective of this randomized clinical trial was to investigate the effects of perfusion modalities on cerebral hemodynamics, vital organ injury, quantified by the Pediatric Logistic Organ Dysfunction-2 (PELOD-2) Score, and clinical outcomes in risk-stratified congenital cardiac surgery patients. MethodsThis randomized clinical trial included 159 consecutive congenital cardiac surgery patients in whom pulsatile (n = 83) or nonpulsatile (n = 76) perfusion was used. Cerebral hemodynamics were assessed using transcranial Doppler ultrasound. Multiple organ injury was quantified using the PELOD-2 score at 24, 48, and 72 hours. Clinical outcomes, including intubation time, intensive care unit length of stay (LOS), hospital LOS, and mortality, were also evaluated. ResultsThe Pulsatility Index at the middle cerebral artery and in the arterial line during aortic cross-clamping was consistently better maintained in the pulsatile group. Demographics and cardiopulmonary bypass characteristics were similar between the 2 groups. While risk stratification with The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) Mortality Categories was similar between the groups, Mortality Categories 1 to 3 demonstrated more patients than Mortality Categories 4 and 5. There were no differences in clinical outcomes between the groups. The PELOD-2 scores showed a progressive improvement from 24 hours to 72 hours, but the results were not statistically different between the groups. ConclusionsThe Pulsatillity Index for the pulsatile group demonstrated a more physiologic pattern compared with the nonpulsatile group. While pulsatile perfusion did not increase plasma-free hemoglobin levels or microemboli delivery, it also did not demonstrate any improvements in clinical outcomes or PELOD-2 scores, suggesting that while pulsatile perfusion is a safe method, it not a “magic bullet” for congenital cardiac operations.

The effect of pulsatile versus non-pulsatile flow during cardiopulmonary bypass on cerebral oxygenation: A randomized trial.

The present study aims to compare regional oxygen supply determined by Near-Infrared Spectroscopy in the course of pulsatile perfusion with non-pulsatile perfusion during cardiopulmonary bypass in patients undergoing valvular heart surgery. In this prospective randomized single-blinded trial, we enrolled adult subjects aged 18-65 years scheduled for elective valvular heart repair/replacement surgery with non-stenotic carotid arteries, employing a consecutive sampling method. Eligible patients were then randomly assigned in a 1:1 ratio to pulsatile or non-pulsatile perfusion during aortic cross-clamp. The primary outcome was regional cerebral oxygenation monitored by Near-Infrared Spectroscopy in each group. Seventy patients were randomly assigned, and each group comprised 35 patients. Mean age was 46.8 and 46.5 years in pulsatile and non-pulsatile groups, respectively. There were no significant between-group differences in regional cerebral oxygen saturation at different time points of cardiopulmonary bypass (p-value for analysis of variance repeated measures: 0.923 and 0.223 for left and right hemispheres, respectively). Moreover, no significant differences in regional cerebral oxygen saturation levels from baseline between pulsatile and non-pulsatile groups at all desired time points for the left (p = 0.51) and right (p = 0.22) hemispheres of the brain were detected. Pulsatile perfusion during cardiopulmonary bypass does not offer superior regional cerebral oxygenation measured by Near-Infrared Spectroscopy than non-pulsatile perfusion during cardiopulmonary bypass. Nonetheless, the efficacy of pulsatile flow in the subgroup of patients in whom cerebral blood flow is impaired due to carotid artery stenosis needs to be explored and evaluated by this method in future studies.

Effects of Pulsatile and Non-Pulsatile Perfusion On Oxygenator Fibers During Pediatric Cardiopulmonary Bypass

In cardiopulmoner operations patients can be perfused with a pulsatile or nonpulsatile pump mode. The extra energy maintained by the pulsatile perfusion may have different effects on the patient and the oxygenator fiber rather than nonpulsatile perfusion. Especially the effect of pulsatile perfusion on the fibers isn’t clearly known. The purpose of this study is to investigate the effects of pulsatile and non-pulsatile blood flows on oxygenator fibers. 18 out of 32 patients that had an pediatric open heart surgery was chosen according to their aortic clamp times. 9 of 18 patients were perfused in a pulsatile mode, other 9 patients were perfused in a nonpulsatile mode. The patient blood was collected before the open heart surgery (T1), before aortic clamp (T2), after aortic clamp (T3), after 1st intensive care hour (T4) and after the 1st intensive care day (T5) in order to compare the results of whole blood and plasma proteins. At the end of the open heart operation 10 cm of oxygenator fiber was removed from the fiber bundle and taken into the phosfate buffer saline (PBS) solution after the patient had a stabile outcome. Whole blood and micro protein measurements were applied in both first fiber solution and sonicated solution. No harmful effect of pulsatile perfusion on blood cells and proteins was observed according to patient results. More blood cell aggregation and total protein adsorption was observed in nonpulsatile mode fibers results. In this study pulsatile perfusion maintained better blood compability over nonpulsatile perfusion and the extra energy in pulsatile perfusion caused better microcirculation.

Extracorporeal circulation during on-pump cardiac surgery: An evaluation of the energy equivalent pressure index based on waveforms decomposition in harmonics.

The use of pulsatile perfusion instead of nonpulsatile perfusion during cardiopulmonary bypass continues to be a source of debate. The disagreements among the conclusions of the published studies may be due to different factors: differences in the type of patients included in the studies, differences in the protocol of the studies, and difficulty to quantify the pulsatility of the flow. In the present paper, we propose a quantitative evaluation of Shepard's energy equivalent pressure index, based on the harmonic decomposition of the physiological aortic pressure and flow rate signal. It is thus demonstrated that the surplus energy provided by pulsatile flow remains moderate (of order 10mmHg), but that it can be improved by changing the relative shapes of the pressure and flow waves.

Pulsatil ve Nonpulsatil Kardiyopulmoner Baypas ile Koroner Baypas Cerrahisi Uygulanan Hastalarda Nörokognitif Değişikliklerin Elektroensefalografi ve Minimental Test Kullanılarak Değerlendirilmesi

Introduction: The aim of this study was to compare the neurocognitive effects of pulsatile and non-pulsatile perfusion using electroencephalography and the Mini-Mental State Examination (MMSE) in patients undergoing coronary bypass surgery. Patients and Methods: We created two groups, each containing 11 consecutive randomized patients, who were candidates for coronary bypass surgery. Pulsatile cardiopulmonary bypass (CPB) was conducted in Group I, and non-pulsatile CPB was conducted in Group II. An electroencephalogram (EEG) was performed preoperatively, intraoperatively, 15 minutes after placement of the cross-clamp, and seven days postoperatively. The MMSE was performed preoperatively and on postoperative day seven. Results: In both groups, pathological EEG waves were detected intraoperatively. However, no statistically significant difference was found between the groups (p> 0.05). Urine output was significantly higher at postoperative day1 in Group I. Overall urine drainage was higher in Group I, but the difference was not statistically significant. Diabetes mellitus, hypercholesterolemia, hypertension, cross-clamp, and perfusion time did not have a significant impact on the formation of pathological EEG waves. The difference between pre- and postoperative MMSE scores was not statistically significant (p> 0.05). Conclusion: No remarkable superiority was shown between CPB pulsatile and non-pulsatile perfusion in our study. Improving physiology of perfusion techniques during CPB and performing further studies on patients at high risk for organ perfusion would suggest more comprehensive perfusion flow strategies.

Uncoupling of cerebral blood flow and brain oxygen saturation under non-pulsatile flow conditions

Introduction Non-pulsatile blood flow has been associated with altered microcirculatory perfusion. Soon after loss of pulsatility a marked heterogenous flow profile in the very small vessels ensues that is coupled with impaired oxygen extraction [1]. We investigated if changes in cerebral blood flow during non-pulsatile perfusion would affect brain tissue oxygenation assessed by near-infrared spectroscopy. Methods After approval by the local ethics committee thirty-two patients were included in this trial. They were studied during general anaesthesia, and stable hemodynamic conditions. Cerebral blood flow velocity in the middle cerebral artery was measured during non-pulsatile flow in the course of cardiac surgery on total extracorporeal bypass and again postoperatively on the intensive care unit during pulsatile flow. We modified cerebral blood flow by changing arterial partial pressures of carbon dioxide between 30, 40 and 50 mmHg. This was conducted either by a change of sweep gas flow at the heart lung machine or by changing respiratory rate at the respirator. In addition to flow measurements patients' regional brain oxygenation was determined. Relative changes in blood flow velocity were plotted against relative changes in regional brain saturation for both flow conditions and compared using Pearson's correlation. A p-value Results Absolute cerebral blood flow velocity was slightly higher during non-pulsatile flow when serum hemoglobin was diluted. Relative changes in cerebral blood flow velocity and regional brain oxygenation were tightly coupled independent of the flow condition. R-values for non-pulsatile and pulsatile blood flow were 0.724 and 0.796, respectively. However, during non-pulsatile flow the slope of the regression line was less steep as compared with pulsatile flow (P Discussion Despite greater cerebral perfusion during hypercapnia and non-pulsatile flow there was no equivalent rise in cerebral oxygenation. Assuming similar cerebral oxygen delivery this finding could be explained by impaired brain oxygen extraction in the high flow range while partial pressure of carbon dioxide was elevated. In contrast, during hypocapnia, when cerebral blood flow was decreased to a greater extent as during pulsatile flow, the concomitant desaturation was less pronounced. Both findings are in line with shunting on the microcirculatory level, whereby hyperperfused vessels coexist with vessels lacking adequate flow. These findings substantiate that loss of pulsatility seems to negatively affect nutritive tissue perfusion. Raised neurological morbidity in patients supported with non-pulsatile extracorporeal cardiac assist devices could potentially be attributable to the observed perfusion deficit [2].

Monitoring and optimization of the microcirculation during CPB.

In this review the impact of cardiopulmonary bypass (CPB) on the microcirculation is discussed. The impact of conventional non-pulsatile perfusion is contrasted with the microcirculatory impact of pulsatile CPB which is associated with better preservation of microcirculatory function. Evidence that alterations in microcirculatory function that persist following cardiac surgery are associated with adverse clinical outcomes is reviewed. Recent studies using novel techniques employing near infrared reflectance spectroscopy (NIRS) and sublingual microscopy to explore alterations in microcirculatory function during CPB are reviewed and the implications of these observations for studies investigating minimally invasive extracorporeal circulation (MiECC) are discussed.

The Association Between Pulsatile Cardiopulmonary Bypass and Acute Kidney Injury After Cardiac Surgery: A Before-and-After Study

To investigate the association between pulsatile perfusion and cardiac surgery-associated acute kidney injury. An uncontrolled, retrospective before-and-after study. Single tertiary hospital. A total of 2,489 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Pulsatile versus nonpulsatile perfusion. Data for nonpulsatile perfusion was collected from April 1, 2016, to March 31, 2017 (n = 1,223). A practice change to universal pulsatile CPB occurred on April 3, 2017. Data for pulsatile perfusion was collected from May 1, 2017, to June 30, 2018 (n = 1,266). The primary outcome was the incidence of acute kidney injury (AKI) after cardiac surgery. Multivariable analysis was carried out to adjust for known confounders. Secondary outcomes included AKI stage, stroke, length of stay, and mortality. Subgroup analyses were carried out using prolonged CPB and chronic kidney disease. The primary outcome, incidence of AKI, did not differ between the nonpulsatile control group and the pulsatile group (23.9% v 25.4%, p = 0.392). The pulsatile group was not associated with AKI in the multivariable analysis (Odds ratio 1.09, p = 0.413). There were no differences in stages of AKI in the nonpulsatile group v pulsatile group (13.6% v 14.9%, 2.9% v 4.3%, and 7.4% v 6.1% for stages 1, 2, and 3, respectively, p = 0.12). There were no differences in subgroup analyses or secondary outcomes. There was no association found between kidney injury and pulsatile perfusion. It is likely that there is either no association between pulsatile perfusion and reduced kidney injury or that the difference is extremely small.

Analysis of blood flow energy characteristics of pulsatile and non-pulsatile flow during extracorporeal circulation

Objective: To analyze the magnitude of blood flow energy and characteristics of frequency domain between pulsatile flow and nonpulsatile flow during cardiopulmonary bypass and physiological flow. Methods: From January 2017 to December 2017, 60 cases of patients with mitral valve disease scheduled for mitral valve replacement or repair at Department of Cardiasurgery, Shanghai Chest Hospital, Shanghai Jiaotong University were randomly divided into 2 groups: pulsatile perfusion (PP) and non-pulsatile perfusion (NP). The magnitude of blood flow energy during pulsatile and non-pulsatile was calculated using energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) while fast Fourier transformation (FFT) was used to perform power spectral density analysis to identify the frequency domain characteristics between artificial and physiological flow (prior to CPB). The data was analyzed by analysis of variance or t test. Results: At the different time-points after occlusion, the EEP and SHE in PP group were respectively 1.52 to 1.62 and 2.03 to 2.22 times higher than NP at the distal of artery filter. The power density analysis revealed that the blood flow energy of physiological pulsatile flow patterns was within 40 Hz and the ratio of low frequency energy was more than 90% before clamp. The spectral energy ratio of low frequency decreased in both group compared with physiological flow was more obvious in NP group at the radial artery. The ratio of estimated value of power density of PP and NP groups analysis showed the corresponding 0 to 5 Hz, 0 to 10 Hz, 0 to 40 Hz frequency range values measured at the radial artery and filter were 9.51, 4.68, 3.59 and 3.87, 2.69, 2.38 respectively after occulusion. In each frequency range, the energy of PP is higher than that of NP, and the lower the frequency, the greater the difference. The ratio of estimated value of power density of PP and NP groups for the three frequencies measured at the radial artery before and after occlusion were 2.86, 2.83, 2.75 and 14.70, 12.74, 9.85 respectively, and decreased significantly in NP group and low frequency energy. The ratio of estimated value of power density of PP and NP groups under the three different frequencies measured at the radial artery and filter were 26.35, 33.15, 37.36 and 37.41, 54.18, 56.64 respectively, in the conduction process from filter to radial artery, energy exhaustion is significant, especially in group NP. Conclusions: The PP provides significantly more energy than the NP whereby the PP is closer to the physiological pulsatile on the energy frequency structure and attenuation characteristics, with mainly low frequency energy of 0 to 5 Hz and weak energy attenuation. The energy loss of non-pulsatile flow is obvious, especially the low frequency energy.

The outcome of pediatric patients undergoing congenital cardiac surgery under pulsatile cardiopulmonary bypass in different frequencies.

PurposeTo investigate the influence and possible pathophysiological mechanism of pulsatile cardiopulmonary bypass (CPB) in various frequencies in pediatric patients undergoing congenital cardiac surgery.Patients and methodsClinical data and hemodynamic parameters were collected in 80 patients who underwent congenital cardiac surgeries and were perfused in different settings: pulsatile perfusion (PP) in frequencies of 30 beats/min, PP 60 beats/min, PP 100 beats/min and non-pulsatile perfusion (NP). Serum proteins, plasma-free hemoglobin (PFH), endothelin-1 (ET-1) and nitric oxide (NO) were collected to study possible pathophysiological changes, possible hematological injury and oxidative status under different perfusing conditions.ResultsPatients in all groups had similar baseline characteristics, aortic cross-clamping time and CPB duration. More effective pulse gradient (PG), energy-equivalent pressure (EEP) and surplus hemodynamic energy (SHE) were observed in pulsatility with lower frequency setting, under which more patients achieved physiologically normal mean arterial pressure (MAP), without the support of inotropic agents during bypass. Significant between-group differences of serum proteins and PFH were absent the whole time during and after bypass, while a relatively lower percentage of perioperative requirement of diuretics was observed in the low frequency pulsatile group. A better performance to oxidative stress was seen in the low frequency group with higher levels of NO and lower concentration of ET-1, and both intergroup differences were found (P<0.01). Satisfactory clinical outcome was obtained on post procedure course in all groups.ConclusionPulsatile perfusion with low frequency setting in pediatric patients undergoing congenital cardiac surgery showed better hemodynamic profiles, potential protective effects on vital organs, better oxidative status and satisfactory clinical outcome.

BOP02-8 - The impact of non-pulsatile perfusion on cerebral blood flow and brain oxygenation

Pulsatile perfusion on cardiopulmonary bypass (CPB) is frequently recommended to enhance brain protection (1). Its impact on cerebral blood flow's (CBF) CO2 reactivity and brain oxygenation, however, has not been systematically investigated yet.

Effect of pulsatile flow perfusion on decellularization

BackgroundDecellularized animal organs have been used as scaffolds for tissue engineering. To make a properly functioning scaffolds, the extracellular matrix (ECM) components must be preserved after decellularization. Because pulsatile flow is known to be beneficial for tissue perfusion, pulsatile perfusion of a detergent might decrease the exposure time of the tissues to the detergent used for decellularization. Using Energy Equivalent Pressure (EEP) as a pulsatility parameter, the effect of pulsatile flow in decellularization process is studied.ResultsTwelve rat hearts were decellularization with 1% sodium dodecyl sulfate (SDS) solution for 2 h. They are divided into two groups, one with pulsatile perfusion (n = 6), the other with non-pulsatile perfusion (n = 6) of SDS. The initial mean perfusion pressures were same in both group. The result indicated that the EEP and the perfusion flow were increased significantly in the pulsatile group compared to the non-pulsatile group. Photographs taken during the decellularization showed more profound decellularization in the pulsatile group. The residual DNA content in the scaffolds was significantly lower in the pulsatile group. However, the level of ECM components, collagen and GAG showed no significant differences between the groups.ConclusionsDecellularization is more efficient in pulsatile flow than in non-pulsatile flow but still preserves the ECM molecules.

Microvascular Responsiveness to Pulsatile and Nonpulsatile Flow During Cardiopulmonary Bypass

Pulsatile perfusion may offer microcirculatory advantages over conventional nonpulsatile perfusion during cardiopulmonary bypass (CPB). Here, we present direct visual evidence of microvascular perfusion and vasoreactivity between perfusion modalities. A prospective, randomized cohort study of 20 high-risk cardiac surgical patients undergoing pulsatile (n= 10) or nonpulsatile (n= 10) flow during CPB was conducted. Changes in sublingual mucosal microcirculation were assessed with orthogonal polarization spectral imaging along with near-infrared spectroscopic indices of thenar muscle tissue oxygen saturation (StO2) and its recovery during a vascular occlusion test at the following time points: baseline (T0), 30 minutes on CPB (T1), 90 minutes on CPB (T2), 1 hour after CPB (T3), and 24 hours after CPB (T4). On the basis of our scoring scale, a shift in microcirculatory blood flow occurred over time. The pulsatile group maintained normal perfusion characteristics, whereas the nonpulsatile group exhibited deterioration in perfusion during CPB (T2: 74.0% ± 5.6% versus 57.6% ± 5.0%) and after CPB (T3: 76.2% ± 2.7% versus 58.9% ± 5.2%, T4: 85.7% ± 2.6% versus 69.8% ± 5.9%). Concurrently, no important differences were found between groups in baseline StO2 and consumption slope at all time points. Reperfusion slope was substantially different between groups 24 hours after CPB (T4: 6.1% ± 0.6% versus 3.7% ± 0.5%), indicating improved microvascular responsiveness in the pulsatile group versus the nonpulsatile group. Pulsatility generated by the roller pump during CPB improves microcirculatory blood flow and tissue oxygen saturation compared with nonpulsatile flow in high-risk cardiac surgical patients, which may reflect attenuation of the systemic inflammatory response and ischemia-reperfusion injury.

Isolated kidney perfusion: the influence of pulsatile flow

Within the scope of transplantation research, ex vivo kidney perfusion has been proven an attractive model to study ischemia-reperfusion and preservation injury. Renal perfusion techniques also occupy scientists with the aim to optimize organ reconditioning and preparation prior to transplantation. This study investigated the influence of a pulsatile perfusion pattern that brings flow conditions closer to physiological situations, on renal perfusion characteristic and kidney function in the isolated perfused kidney. Kidneys were perfused via a roller pump at constant pressure set to 90 mmHg, or with addition of pulsatile pressure peaks (90/70 mmHg; 60/min) using an adjustable positive displacement pump. It was found that pulsatile pressure significantly enhanced renal flow rates as compared to non-pulsatile perfusion mode, especially after preceding preservation of the kidney by static cold storage. The improved vascular conductivity went along with a notable improvement of clearance of creatinine, sodium reabsorption and reduced tubular cell injury (Loss of fatty acid binding protein). The better vascular conductance upon pulsatile perfusion could be attributed to improved endothelial release of nitic oxide and reduced secretion of endothelin-1 into the perfusate. It is concluded, that pulsatile perfusion mode should be preferred in isolated kidney perfusion as resulting in better preservation/recovery of renal perfusion and function.

Pulmonary Bleeding During Right Ventricular Support After Left Ventricular Assist Device Implantation.

Right heart failure still occurs in up to 20% of patients after implantation of a left ventricular assist device (LVAD). One treatment option for these patients is the implantation of a temporary right ventricular assist device (RVAD). Experimental data suggest that non-pulsatile perfusion of the lungs is associated with an increased rate of pulmonary hemorrhage. The aim of this study was to determine the incidence of pulmonary bleeding complications in these patients. Observational study. Single center, university hospital. This study included patients undergoing LVAD implantation for end-stage heart failure and subsequent implantation of a temporary right ventricular support system. In this study, 25 patients who underwent LVAD and additional temporary RVAD implantation were screened for pulmonary bleeding complications. The mean Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level at the time of LVAD implantation was 2.84. All patients experienced severe right ventricular failure (tricuspid annular plane systolic excursion [TAPSE], 10.16±26.3 mm) and severe pulmonary hypertension (right atrial [RA] pressure, 56.21±15.58 mmHg). Average duration of right ventricular support was 11.12±7.20 days, with right ventricular support being administered to 14 patients for more than 7 days. Seventeen patients were weaned successfully from right ventricular support after a mean support duration of 5 days. Five patients developed pulmonary bleeding complications, diagnosed using computed tomography scan and bronchoscopy. All bleeding occurred after postoperative day 7 and was associated with RVAD flow of more than 4 L/min within 24 hours before bleeding occurred. The data presented in this study suggested that right ventricular support for more than 7 days and a blood flow greater than 4 L/min were associated with pulmonary bleeding complications. This should be taken into consideration when temporary right ventricular support after LVAD implantation is planned.

A Meta-Analysis of Renal Function After Adult Cardiac Surgery With Pulsatile Perfusion.

The aim of this meta-analysis was to determine whether pulsatile perfusion during cardiac surgery has a lesser effect on renal dysfunction than nonpulsatile perfusion after cardiac surgery in randomized controlled trials. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were used to identify available articles published before April 25, 2014. Meta-analysis was conducted to determine the effects of pulsatile perfusion on postoperative renal functions, as determined by creatinine clearance (CrCl), serum creatinine (Cr), urinary neutrophil gelatinase-associated lipocalin (NGAL), and the incidences of acute renal insufficiency (ARI) and acute renal failure (ARF). Nine studies involving 674 patients that received pulsatile perfusion and 698 patients that received nonpulsatile perfusion during cardiopulmonary bypass (CPB) were considered in the meta-analysis. Stratified analysis was performed according to effective pulsatility or unclear pulsatility of the pulsatile perfusion method in the presence of heterogeneity. NGAL levels were not significantly different between the pulsatile and nonpulsatile groups. However, patients in the pulsatile group had a significantly higher CrCl and lower Cr levels when the analysis was restricted to studies on effective pulsatile flow (P < 0.00001, respectively). The incidence of ARI was significantly lower in the pulsatile group (P < 0.00001), but incidences of ARF were similar. In conclusion, the meta-analysis suggests that the use of pulsatile flow during CPB results in better postoperative renal function.

Calibrating Doppler imaging of preterm intracerebral circulation using a microvessel flow phantom.

Introduction: Preterm infants are born during critical stages of brain development, in which the adaptive capacity of the fetus to extra-uterine environment is limited. Inadequate brain perfusion has been directly linked to preterm brain damage. Advanced high-frequency ultrasound probes and processing algorithms allow visualization of microvessels and depiction of regional variation. To assess whether visualization and flow velocity estimates of preterm cerebral perfusion using Doppler techniques are accurate, we conducted an in vitro experiment using a microvessel flow phantom.Materials and Methods: An in-house developed flow phantom containing two microvessels (inner diameter 200 and 700 μm) with attached syringe pumps, filled with blood-mimicking fluid, was used to generate non-pulsatile perfusion of variable flow. Measurements were performed using an Esaote MyLab70 scanner.Results: Microvessel mimicking catheters with velocities as low as 1 cm/s were adequately visualized with a linear ultrasound probe. With a convex probe, velocities <2 cm/s could not be depicted. Within settings, velocity and diameter measurements were highly reproducible [intra-class correlation 0.997 (95% CI 0.996–0.998) and 0.914 (0.864–0.946)]. Overall, mean velocity was overestimated up to threefold, especially in high velocity ranges. Significant differences were seen in velocity measurements when using steer angle correction and in vessel diameter estimation (p < 0.05).Conclusion: Visualization of microvessel-size catheters mimicking small brain vessels is feasible. Reproducible velocity and diameter results can be obtained, although important overestimation of the values is observed. Before velocity estimates of microcirculation can find its use in clinical practice, calibration of the ultrasound machine for any specific Doppler purpose is essential. The ultimate goal is to develop a sonographic tool that can be used for objective study of regional perfusion in routine practice.