Neurocognitive Function in Patients Undergoing Coronary Artery Bypass Graft Surgery With Cardiopulmonary Bypass: The Effect of Two Different Rewarming Strategies

The effect of rewarming on hemodynamic parameters and arterial blood gases of patients after open-heart surgery: A randomized controlled trial

INTRODUCTION

Hypothermia after open-heart surgery can have potential side effects for patients.

AIM

This study aimed to examine the effects of rewarming on patients' hemodynamic and arterial blood gases parameters after open-heart surgery.

METHODS

This randomized controlled trial was performed in 2019 on 80 patients undergoing open-heart surgery at Tehran Heart Center, Iran. The subjects were consecutively recruited and randomly assigned to an intervention group (n=40) and a control group (n=40). After the surgery, the intervention group was warmed with an electric warming mattress while the control group warmed using a simple hospital blanket. The hemodynamic parameters of the two groups were measured 6 times and arterial blood gas was measured 3 times. Data were analyzed by independent samples t and Chi-squared tests, and repeated measures analysis.

RESULTS

Before the intervention, the two groups did not significantly differ in terms of hemodynamic and blood gas parameters. However, the two groups were significantly different in the mean heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, temperature, right and left lung drainage in the first half-hour, and the first to fourth hours after the intervention (p < 0.05). Furthermore, there was a significant difference between the mean arterial oxygen pressure of the two groups during and after rewarming (P <0.05).

CONCLUSION

Rewarming of patients after open-heart surgery can significantly affect hemodynamic and arterial blood gas parameters. Therefore, rewarming methods can be used safely to improve the patients' hemodynamic parameters after open-heart surgery.

Rapid cooling is a safe technique in patients undergoing circulatory arrest for aortic repair

Objective

To evaluate our institutional experience with rapid cooling for hypothermic circulatory arrest in proximal aortic repair.

Methods

We retrospectively reviewed data from 2171 patients who underwent proximal aortic surgery requiring hypothermic circulatory arrest between 1991 and 2020. Cooling times were divided into quartiles and clinical outcome event rates were compared across quartiles using contingency table methods. Incremental effect of cooling time was assessed in the context of other perfusion time variables using multiple logistic regression analysis.

Results

Median age was 61 years (interquartile range, 49-70 years) and 34.1% of patients were women. The procedure was emergent in 33.5% of patients, 22.9% had a previous sternotomy. The median circulatory arrest time was 22 minutes, with retrograde cerebral perfusion used in 94% of cases. Median cardiopulmonary bypass time was 149 minutes, with an aortic crossclamp time of 90 minutes. Patients were cooled to deep hypothermia. The first quartile had cooling times ranging from 5 to 13 minutes, second 14 to 18 minutes, third 19-23 minutes, and fourth 24-81 minutes. Overall, 30-day mortality was 9.4%, and was not significantly different across quartiles. There was a statistically significant trend toward lower rates of postoperative encephalopathy, gastrointestinal complications, and respiratory failure with shorter cooling times (P < .001, .006, and < .001, respectively). There was no significant difference in rates of postoperative stroke or dialysis.

Conclusions

Rapid cooling can be performed safely in patients undergoing aortic surgery requiring circulatory arrest without increasing mortality or stroke. There were significantly lower rates of coagulopathy, respiratory failure, and postoperative encephalopathy with shorter cooling times.

S100B in cardiac surgery brain monitoring: friend or foe?

Recent advances in perioperative management of adult and pediatric patients requiring open heart surgery (OHS) and cardiopulmonary bypass (CPB) for cardiac and/or congenital heart diseases repair allowed a significant reduction in the mortality rate. Conversely morbidity rate pattern has a flat trend. Perioperative period is crucial since OHS and CPB are widely accepted as a deliberate hypoxic-ischemic reperfusion damage representing the cost to pay at a time when standard of care monitoring procedures can be silent or unavailable. In this respect, the measurement of neuro-biomarkers (NB), able to detect at early stage perioperative brain damage could be especially useful. In the last decade, among a series of NB, S100B protein has been investigated. After the first promising results, supporting the usefulness of the protein as predictor of short/long term adverse neurological outcome, the protein has been progressively abandoned due to a series of limitations. In the present review we offer an up-dated overview of the main S100B pros and cons in the peri-operative monitoring of adult and pediatric patients.

Targeted temperature management in cardiac surgery: a systematic review and meta-analysis on postoperative cognitive outcomes

BACKGROUND

Postoperative cognitive decline occurs commonly after cardiac surgery. The available literature is inconclusive on the role of intraoperative causal or protective factors.

METHODS

We systematically reviewed studies evaluating delayed neurocognitive recovery (DNR), postoperative neurocognitive disorder (NCD), stroke, and the mortality rates among patients undergoing hypothermic or normothermic cardiopulmonary bypass (CPB). We further performed a subgroup analysis for age, surgery type (coronary artery bypass grafting [CABG], valve surgery, or combined), and the mean arterial blood pressure (MAP) during CPB, and conducted a proportion meta-analysis after calculation of single proportions and confidence intervals (CIs).

RESULTS

We included a total of 58 studies with 9609 patients in our analysis. Among these, 1906 of 4010 patients (47.5%) had DNR, and 2071 of 7160 (28.9%) had postoperative NCD. Ninety of 4625 patients (2.0%) had a stroke, and 174 of 7589 (2.3%) died. There was no statistically significant relationship between the considered variables and DNR, NCD, stroke, and mortality. In the subgroup analysis comparing hypothermic with normothermic CPB, we found higher NCD rates after combined surgery; for normothermic CPB cases only, the rates of DNR and NCD were lower after combined surgery compared with CABG surgery. A MAP >70 mm Hg compared with MAP=50-70 mm Hg during CPB was associated with a lower rate of DNR.

CONCLUSIONS

Temperature, MAP during cardiopulmonary bypass age, and surgery type were not associated with neurocognitive disorders, stroke, and mortality in cardiac surgery. Normothermic cardiopulmonary bypass, particularly when performed with MAP >70 mm Hg, may reduce the risk of postoperative neurocognitive decline after cardiac surgery.

PROSPERO REGISTRATION NUMBER

CRD42019140844.

Brain Protection in Aortic Arch Surgery: An Evolving Field

Despite advances in cardiac surgery and anesthesia, the rates of brain injury remain high in aortic arch surgery requiring circulatory arrest. The mechanisms of brain injury, including permanent and temporary neurologic dysfunction, are multifactorial, but intraoperative brain ischemia is likely a major contributor. Maintaining optimal cerebral perfusion during cardiopulmonary bypass and circulatory arrest is the key component of intraoperative management for aortic arch surgery. Various brain monitoring modalities provide different information to improve cerebral protection. Electroencephalography gives crucial data to ensure minimal cerebral metabolism during deep hypothermic circulatory arrest, transcranial Doppler directly measures cerebral arterial blood flow, and near-infrared spectroscopy monitors regional cerebral oxygen saturation. Various brain protection techniques, including hypothermia, cerebral perfusion, pharmacologic protection, and blood gas management, have been used during interruption of systemic circulation, but the optimal strategy remains elusive. Although deep hypothermic circulatory arrest and retrograde cerebral perfusion have their merits, there have been increasing reports about the use of antegrade cerebral perfusion, obviating the need for deep hypothermia. With controversy and variability of surgical practices, moderate hypothermia, when combined with unilateral antegrade cerebral perfusion, is considered safe for brain protection in aortic arch surgery performed with circulatory arrest. The neurologic outcomes of brain protection in aortic arch surgery largely depend on the following three major components: cerebral temperature, circulatory arrest time, and cerebral perfusion during circulatory arrest. The optimal brain protection strategy should be individualized based on comprehensive monitoring and stems from well-executed techniques that balance the major components contributing to brain injury.

Health-related quality of life one year after surgical treatment of the type I chronic aortic dissection

BACKGROUND

The purpose of our study was to assess the health-related quality of life (HRQoL) in patients with type I chronic aortic dissection before and one year after prosthetics of the aorta, and to test the hypothesis that long-term postoperative parameters of HRQoL are affected by clinical determinants related to the underlying disease, intraoperative characteristics, and complications of the early postoperative period.

METHODS

This prospective cohort study included 82 patients with type I chronic aortic dissection. HRQoL parameters were examined using the Short-Form 36 Health Survey Questionnaire before and one year after surgery.

RESULTS

Patients with aortic dissection one year after surgery demonstrated an improvement in many HRQoL parameters, including two summary measures of the questionnaire - Physical component summary (PCS) and Mental component summary (MCS). A lower level of PCS and MCS at the preoperative stage significantly predicted lower values of these indices for a long time after aortic prosthetics. The neurological complications in the early postoperative period were the factor affecting the MCS after surgery. Moreover, the neurological complications and the presence of coronary artery disease increased the risk of the adverse outcomes, including aortic related death and significant decrease of MCS or aortic related death and significant decrease of PCS one year after the operation, respectively.

CONCLUSIONS

Surgical treatment in patients with type I chronic aortic dissection leads to an increase of many HRQoL parameters. Factors affecting MCS and PCS one year after surgery included the neurological complications and lower level of the MCS and PCS at the preoperative stage. Furthermore, the neurological complications and the presence of coronary artery disease increased the risk of the combined endpoints - aortic related death and significant decrease of MCS or aortic related death and significant decrease of PCS one year after the operation, respectively.

Short-Term Postoperative Cognitive Dysfunction and Inflammatory Response in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: A Pilot Study

Objectives

To assess the association between short-term postoperative cognitive dysfuction (POCD) and inflammtory response in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).

Design

A prospective cohort study.

Setting

University medical centre.

Participants

Fifty-one adult patients who had undergone CRS-HIPEC and twenty control participants.

Measurements

The inflammatory marker levels in plasma and cognitive function were measured.

Results

Twenty (39.2%, 20/51) patients developed POCD at 1 w after CRS-HIPEC. The patients with POCD had higher serum interleukin 1β (IL-1β), serum amyloid A (SAA), S100 calcium-binding protein β (S-100β), and high mobility group box-1 protein (HMGB-1) levels at 1 and 24 h postoperatively than patients without POCD. There was an association between POCD and the maximum IL-1β and S-100β concentrations in serum, which remained following adjustment for age and FBS.

Conclusion

In this pilot study, perioperative inflammatory marker levels increase significantly after CRS-HIPEC in adult patients, and such elevations are associated with the development of short-term cognitive dysfunction after this complex surgery. These results suggested the need for a larger RCT to replicate and confirm these findings.

Aortic Surgery and Deep-Hypothermic Circulatory Arrest: Anesthetic Update

Aortic arch surgery has become increasingly complex, and novel surgical approaches have been utilized. Efforts aimed at improving neurological outcomes in this patient population have been numerous, with varying degrees of success. This article summarizes the anesthetic considerations for procedures on the aortic arch, including evidence-based outcomes with respect to temperature management, perfusion strategies, hemodynamic goals, adjunct agents, and neuromonitoring.

Risk Factors Associated with Cognitive Decline after Cardiac Surgery: A Systematic Review

Modern day cardiac surgery evolved upon the advent of cardiopulmonary bypass machines (CPB) in the 1950s. Following this development, cardiac surgery in recent years has improved significantly. Despite such advances and the introduction of new technologies, neurological sequelae after cardiac surgery still exist. Ischaemic stroke, delirium, and cognitive impairment cause significant morbidity and mortality and unfortunately remain common complications. Postoperative cognitive decline (POCD) is believed to be associated with the presence of new ischaemic lesions originating from emboli entering the cerebral circulation during surgery. Cardiopulmonary bypass was thought to be the reason of POCD, but randomised controlled trials comparing with off-pump surgery show contradictory results. Attention has now turned to the growing evidence that perioperative risk factors, as well as patient-related risk factors, play an important role in early and late POCD. Clearly, identifying the mechanism of POCD is challenging. The purpose of this systematic review is to discuss the literature that has investigated patient and perioperative risk factors to better understand the magnitude of the risk factors associated with POCD after cardiac surgery.

Rapid rewarming after therapeutic hypothermia worsens outcome in sepsis

OBJECTIVE

This study was performed to investigate the effect of the rewarming rate on survival and acute lung injury in sepsis.

METHODS

Male Sprague-Dawley rats underwent cecal ligation and incision. After 1 hour of sepsis induction, normothermia (37°C±0.5°C, NT group) or hypothermia (32°C±0.5°C) was induced. Hypothermia was maintained for 4 hours and rats were divided into two groups according to the rewarming rate: RW1 group, 1 hour of rewarming; and RW2 group, 2 hours of rewarming. In the survival study, rats were observed for 12 hours after sepsis induction (n=6 per group). In the second experiment, rats were sacrificed 7 hours after sepsis induction, and lung tissues and plasma were harvested (n=10 per group).

RESULTS

In the survival study, the RW2 group survived longer than the RW1 group (P<0.05), but the RW1 and NT groups showed no significant difference in survival duration (P>0.05). The histological lung injury score and malondialdehyde concentrations in the lung tissues were significantly higher in the RW1 group than in the RW2 group (P<0.05). Plasma interleukin (IL)-6 concentration and the ratio of IL-6 to IL-10 were higher in the RW1 group than in the RW2 group (P<0.05).

CONCLUSION

Rapid rewarming after therapeutic hypothermia results in a shorter survival period and acute lung injury in sepsis, which could be associated with the inflammatory responses.

Impact of different surgical strategies on perioperative protein S100β release in elderly patients undergoing coronary artery bypass grafting

OBJECTIVE

This study was designed to compare neurological injury-associated protein S100β release during three different treatment modalities, minimized closed circuit coronary artery bypass grafting (CABG) (MCABG), off-pump CABG (OPCAB), and conventional CABG (CCABG), comprising high-volume prime and cold crystalloid cardioplegia. Our working hypothesis was that fluid restriction as provided by MCABG may decrease neurological injury-associated protein S100β release.

METHODS

In this prospective trial, in a tertiary center, 30 surgical patients (aged >70 years, 25 men and 5 women) undergoing first-time elective CABG were enrolled. The inclusion criteria were three-vessel disease and elective surgery. The exclusion criteria were left ventricular ejection fraction of less than 30%, use of clopidogrel, carotid disease, or needing fewer than three distal anastomoses. Protein S100β concentrations, hematocrit (Ht) levels, and PO2 levels were measured after induction of anesthesia, 10 minutes after reperfusion, upon arrival at the intensive care unit, 3 hours postoperatively at the intensive care unit, and the next morning. Statistics consisted of areas under the curve, peak levels, and correlation and variance tests.

RESULTS

A significant negative correlation was found indicating higher S100β release at lower Ht levels and at lower PO2 levels in all study groups. The lowest S100β variance was measured during MCABG (Wilks Λ P = 0.052). The perioperative Ht was significantly higher in the MCABG group and in the OPCAB group compared with the CCABG group (P = 0.04 vs P < 0.01). At all time points, the S100β protein concentration showed no significant differences between the different surgical techniques. The mean (95% confidence interval) values of S100 area under the curve were the following: CCABG, 2.3 (1.06-3.5); MCABG, 1.44 (0.6-2.21); and OPCAB, 1.87 (1.5-2.19) [independent nonparametric Kruskal-Wallis test (P = 0.13)]. The mean (95% confidence interval) peak S100 values (calculated as the maximum value seen in a patient during the research period) were the following: CCABG, 1.07 (0.4-1.68); MCABG, 0.59 (0.28-0.90); and OPCAB, 0.83 (0.59-1.06) [independent nonparametric Kruskal-Wallis test (P = 0.22)].

CONCLUSIONS

Despite similar perioperative S100β protein release for all techniques studied, higher Ht and PO2 levels correlated with lower S100β release within all study groups. The low S100β variance during the fluid restrictive MCABG technique may be due to more efficient oxygen transport to the brain provided by significantly higher perioperative Ht levels. Further prospective data are required to better understand this complex issue.

Overcoming Challenges in the Management of Critical Events During Cardiopulmonary Bypass

Critical events during cardiopulmonary bypass (CPB) can challenge the most experienced perfusionists, anesthesiologists, and surgeons and can potentially lead to devastating outcomes. Much of the challenge of troubleshooting these events requires a key understanding of these situations and a well-defined strategy for early recognition and treatment. Adverse situations may be anticipated prior to going on CPB. Atherosclerosis is pervasive, and a high plaque burden may have implications in surgical technique modification and planning of CPB. Hematologic abnormalities such as cold agglutinins, antithrombin III deficiency, and hemoglobin S have been discussed with emphasis on managing complications arising from their altered pathophysiology. Jehovah’s witness patients require appropriate techniques for cell salvage to minimize blood loss. During initiation of CPB, devastating situations leading to acute hypoperfusion and multiorgan failure may be encountered in patients undergoing surgery for aortic dissection. Massive air emboli during CPB, though rare, necessitate an urgent diagnosis to detect the source and prompt management to contain catastrophic outcomes. Gaseous microemboli remain ubiquitous and continue to be a major concern for neurocognitive impairment despite our best efforts to improve techniques and refine the CPB circuit. During maintenance of CPB, adverse events reflect inability to provide optimal perfusion and can be ascribed to CPB machine malfunction or physiological aberrations. We also discuss critical events that can occur during perfusion and the need to monitor for organ perfusion in altered physiologic states emanating from hemodilution, hypothermia, and acid–base alterations.

Neurologic recovery from profound accidental hypothermia after 5 hours of cardiopulmonary resuscitation

OBJECTIVE

To describe the successful neurologic recovery from profound accidental hypothermia with cardiac arrest despite the longest reported duration of cardiopulmonary resuscitation.

DESIGN

Case report.

SETTING

Mountain.

PATIENT

A 57-year-old woman experienced profound accidental hypothermia (16.9°C) in a mountainous region of Grenoble. She was unconscious and had extreme bradycardia (6 beats/min) at presentation. A cardiac arrest occurred at the mobilization that was not responsive to electrical shocks or epinephrine.

INTERVENTION

Cardiopulmonary resuscitation was continued for 307 minutes after rescue until venoarterial extracorporeal membrane oxygenation blood flow had been established at the emergency department.

MEASUREMENTS AND MAIN RESULTS

At a 3-month follow-up, the patient showed good physical and mental recovery.

CONCLUSION

With no evidence of trauma or asphyxia, profound accidental hypothermia with cardiac arrest represents a specific condition for which successful neurologic recovery is feasible despite prolonged cardiopulmonary resuscitation.

Therapeutic hypothermia following emergent coronary artery bypass grafting after failed percutaneous coronary intervention in a comatose post-cardiac arrest patient

We report the case of 60-yr-old female in which therapeutic hypothermia (TH) was successfully induced maintaining the target temperature of 34℃ for 12 hr despite a risk of hypothermia-induced coagulation abnormalities following an emergent coronary artery bypass grafting (CABG) due to failed percutaneous coronary intervention, who suffered a cardiac arrest. Emergent CABG may be a relative contraindication for TH in post-cardiac arrest patients because hypothermia may increase the risk of infection and bleeding. However, the possibility of an improved neurologic outcome outweighs the risk of bleeding, although major surgery may be a relative contraindication for TH.

Remote ischemic preconditioning protects neurocognitive function of rats following cerebral hypoperfusion

BACKGROUND

Protection of remote ischemic preconditioning on neurocognitive function caused by bilateral common carotid artery occlusion has been investigated in rats.

MATERIAL/METHODS

Thirty-six male Sprague-Dawley rats were divided into 3 groups - control group (Group C, n=12), bilateral carotid arteries occlusion group (Group B, n=12) and remote ischemic precondition group (Group P, n=12). In Group P, remote ischemic preconditioning (RIPC) was performed on the right femoral artery with 3 cycles (10 min) of occlusion/perfusion. After 3 cycles of preconditioning, bilateral carotid arteries were occluded immediately for 60 min. In Group B, ischemic insults were conducted without RIPC. Sham surgeries were performed in Group C. Evaluation of memory and learning capacity was performed on days 5-8 after surgery by Morris water maze testing of spatial learning capacity (n=6 for each group). Apoptosis of cells in the hippocampus region was determined by TUNEL tests and Bcl-2 at this region was determined by ELISA 24 h and 9 days after vessel occlusion (n=6 for each group).

RESULTS

Neurocognitive tests showed that latency time was significantly longer in Group B than in Group P on day 7 (p=0.016) and day 8 (p=0.036). Moreover, frequency of platform crossings was significant less in group B than in the other 2 groups on day 9. Bcl-2 level was significantly increased in the hippocampal region of rats in Group P on days 1 and 9 after vessel occlusion. TUNEL test showed that apoptosis could be observed at 24 h after occlusion in Group B, but not in Group P and Group C. No apoptosis was observed on day 9.

CONCLUSIONS

Our results suggest that RIPC can protect neurocognitive function of rats after bilateral carotid occlusions, and that Bcl-2 may play an important role in this protective effect.

A randomized controlled trial comparing the Arctic Sun to standard cooling for induction of hypothermia after cardiac arrest

CONTEXT

Hypothermia improves neurological outcome for comatose survivors of out-of-hospital cardiac arrest. Use of computer controlled high surface area devices for cooling may lead to faster cooling rates and potentially improve patient outcome.

OBJECTIVE

To compare the effectiveness of surface cooling with the standard blankets and ice packs to the Arctic Sun, a mechanical device used for temperature management.

DESIGN, SETTING, AND PATIENTS

Multi-center randomized trial of hemodynamically stable comatose survivors of out-of-hospital cardiac arrest.

INTERVENTION

Standard post-resuscitative care inducing hypothermia using cooling blankets and ice (n=30) or the Arctic Sun (n=34).

MAIN OUTCOME MEASURES

The primary end point was the proportion of subjects who reached a target temperature within 4h of beginning cooling. The secondary end points were time interval to achieve target temperature (34 degrees C) and survival to 3 months.

RESULTS

The proportion of subjects cooled below the 34 degrees C target at 4h was 71% for the Arctic Sun group and 50% for the standard cooling group (p=0.12). The median time to target was 54 min faster for cooled patients in the Arctic Sun group than the standard cooling group (p<0.01). Survival rates with good neurological outcome were similar; 46% of Arctic Sun patients and 38% of standard patients had a cerebral performance category of 1 or 2 at 30 days (p=0.6).

CONCLUSIONS

While the proportion of subjects reaching target temperature within 4h was not significantly different, the Arctic Sun cooled patients to a temperature of 34 degrees C more rapidly than standard cooling blankets.