Carbon dioxide insufflation in open-chamber cardiac surgery: a double-blind, randomized clinical trial of neurocognitive effects

Totally Endoscopic Atrial Septal Defect Repair on Beating Heart: Clinical Outcome and Single-Surgeon Learning Curve Experience

OBJECTIVE

To evaluate the safety and efficacy of the Hanoi ASD procedure, which is totally endoscopic surgery for atrial septal defect (ASD) repair on beating heart. In addition, the present study also aimed to analyze the learning curve for this procedure.

METHODS

From May 2016 to February 2023, 198 consecutive ASD patients weighing ≥20 kg were enrolled in the retrospective study. The Hanoi ASD procedure includes (1) unilateral or bilateral femoral arterial cannulation; (2) two or three 5 mm trocars and a 15 mm port; (3) ASD repair on beating heart, preventing air embolism with CO2 insufflation and keeping the left atrium full of blood; and (4) not snaring the inferior vena cava. Cumulative sum (CUSUM) analysis was used to evaluate the cardiopulmonary bypass (CPB) and operation time learning curves. Variables among the learning curve phases were compared.

RESULTS

The CPB and operation times were 90 (72 to 115) min and 180 (150 to 220) min, respectively. Total drainage volume was 190 (120 to 290) mL. No endoscopic failure or major complications were complications were excluding factors causing bias, the CUSUMCPBtime analysis for the remaining 131 patients included 3 phases. Phase 1 was the initial learning period (cases 1 to 34), phase 2 represented the technical competence period (cases 35 to 54), and phase 3 was the challenging period (cases 55 to 131).

CONCLUSIONS

The Hanoi ASD procedure is safe and feasible for repairing ASD in patients weighing ≥20 kg. According to the learning curve analysis, 34 cases were required to achieve technical efficiency, and 54 cases were required to address highly challenging cases.

Carbon dioxide flushing versus saline flushing of thoracic aortic stents (INTERCEPTevar): protocol for a multicentre pilot randomised controlled trial

INTRODUCTION

Thoracic endovascular aortic repair (TEVAR) carries a 3%-6.1% stroke risk, including risk of 'silent' cerebral infarction (SCI). Stent-grafts are manufactured in room air and retain air. Instructions for use recommend saline flushing to 'de-air' the system prior to insertion, but substantial amounts of air are released when deploying them, potentially leading to downstream neuronal injury and SCI. Carbon dioxide (CO2) is more dense and more soluble in blood than air, without risk of bubble formation, so could be used in addition to saline to de-air stents. This pilot trial aims to assess the feasibility of a full-scale randomised controlled trial (RCT) investigating the neuroprotective benefit against SCI with the use of CO2-flushed aortic stent-grafts.

METHODS AND ANALYSIS

This is a multicentre pilot RCT, which is taking place in vascular centres in the UK, USA and New Zealand. Patients identified for TEVAR will be enrolled after informed written consent. 120 participants will be randomised (1:1) to TEVAR-CO2 or TEVAR-saline, stratified according to TEVAR landing zone. Participants will undergo preoperative neurocognitive tests and quality of life assessments, which will be repeated at 6 weeks, or first outpatient appointment, and 6 months. Inpatient neurological testing will be performed within 48 hours of return to level 1 care for clinical stroke or delirium. Diffusion-weighted MRI will be undertaken within 72 hours postoperatively (1-7 days) and at 6 months to look for evidence and persistence of SCI. Feasibility will be assessed via measures of recruitment and retention, informing the design of a full-scale trial.

ETHICS AND DISSEMINATION

The study coordination centre has obtained approval from the London Fulham Research Ethics Committee (19/LO/0836) and Southern Health and Disability Ethics Committee (NZ) and UK's Health Regulator Authority (HRA). The study has received ethical approval for recruitment in the UK (Fulham REC, 19/LO/0836), New Zealand (21/STH/192) and the USA (IRB 019-264, Ref 378630). Consent for entering into the study will be taken using standardised consent forms by the local study team, led by a local PI. The results of the trial will be submitted for publication in an open access journal.

TRIAL REGISTRATION NUMBER

NCT03886675.

Warm humidified CO2 insufflation improves pericardial integrity for cardiac surgery: a randomized control study

BACKGROUND

Flooding the surgical field with dry cold CO<inf>2</inf> during open-chamber cardiac surgery has been used to mitigate air entrainment into the systemic circulation. However, exposing epithelial surfaces to cold, dry gas causes tissue desiccation. This randomized controlled study was designed to investigate whether the use of humidified warm CO<inf>2</inf> insufflation into the cardiac cavity could reduce pericardial tissue damage and the incidence of micro-emboli when compared to dry cold CO<inf>2</inf> insufflation.

METHODS

Forty adult patients requiring elective open-chamber cardiac surgery were randomized to have either dry cold CO<inf>2</inf> insufflation via a standard catheter or humidified warm CO<inf>2</inf> insufflation via the HumiGard device (Fisher & Paykel Healthcare, Panmure, Auckland, New Zealand). The primary endpoint was biopsied pericardial tissue damage, assessed using electron microscopy. We assessed the percentage of microvilli and mesothelial damage, using a damage severity score (DSS) system. We compared the proportion of patients who had less damage, defined as DSS<2. Secondary endpoints included the severity of micro-emboli, by visual assessment of bubble load on transesophageal echocardiogram; lowest near infrared spectroscopy; total de-airing time; highest cardio-pulmonary bypass sweep speed; hospital length of stay and complications.

RESULTS

A higher proportion of patients in the humidified warm CO<inf>2</inf> group displayed conserved microvilli (47% vs. 11%, P=0.03) and preserved mesothelium (42% vs. 5%, P=0.02) compared to the control group. There were no differences in the secondary outcomes.

CONCLUSIONS

Humidified warm CO<inf>2</inf> insufflation significantly reduced pericardial epithelial damage when compared to dry cold CO<inf>2</inf> insufflation in open-chamber cardiac surgery. Further studies are warranted to investigate its potential clinical benefits.

Risk factors for postoperative delirium after cardiac surgical procedures with cardioplegic arrest

OBJECTIVES

The pathophysiology of delirium after cardiac surgery is complex. The present study aims to determine perioperative risk factors and construct a scoring system for postoperative delirium based on the type of surgery.

METHODS

Three hundred patients undergoing coronary artery bypass grafting (CABG; n = 150) or valve and/or aortic surgery ± CABG (n = 150) were retrospectively evaluated.

RESULTS

The incidence of delirium (32%) was similar in subgroups (28.7% and 33.33%, P = 0.384). Delirium patients were older [71.3 (standard deviation: 8.5) vs 66.6 (standard deviation: 9.5), P < 0.001; 70.0 (standard deviation: 9.6) vs 62.5 (standard deviation: 12.6), P < 0.001] and required more packed red blood cell units [2.1 (standard deviation: 2.1) vs 4.2 (standard deviation: 4.0), P < 0.001; 2.4 (standard deviation: 3.3) vs 5.4 (standard deviation: 5.9), P < 0.001] and fresh frozen plasma units [6.1 (standard deviation: 2.9) vs. 8.0 (standard deviation: 4.2), P < 0.001; 6.3 (standard deviation: 3.4) vs 10.8 (standard deviation: 7.2), P < 0.001] in CABG and valve/aortic subgroups, respectively. Delirium was associated with longer operation time [298.3 (standard deviation: 98.4) vs 250.6 (standard deviation: 67.8) min, P < 0.001], cardiopulmonary bypass (CPB) time [171.5 (standard deviation: 54.9) vs 140.98 (standard deviation: 45.8) min, P < 0.001] and cardiac arrest time [112 (standard deviation: 35.9) vs 91.9 (standard deviation: 28.6), P < 0.001] only in the valve/aortic group (versus non-delirium). Multivariate regression analysis identified an association between delirium and age [odds ratio: 1.056 (95% confidence interval: 1.002-1.113), P = 0.041], CPB time [odds ratio: 1.1014 (95% confidence interval: 1.004-1.025), P = 0.007], fresh frozen plasma transfusion [odds ratio: 1.127 (95% confidence interval: 1.006-1.262), P = 0.039] and atrial fibrillation [odds ratio: 4.801 (95% confidence interval: 1.844-12.502), P < 0.001] after valve/aortic surgery (area under the curve 0.835, P < 0.001) and between delirium and age [odds ratio: 1.089 (95% confidence interval: 1.023-1.160), P = 0.007] and ventilation time [odds ratio: 1.068 (95% confidence interval: 1.026-1.113), P = 0.001] after isolated CABG (area under the curve 0.798, P < 0.001). The cross-validation of the results by k-fold logistic regression revealed for the entire patient cohort an overall average accuracy of the prediction model of 0.764, with a false-positive rate of 0.052 and a false-negative rate of 0.18.

CONCLUSIONS

Age, CPB time, ventilation, transfusion and atrial fibrillation are differently associated with delirium depending on the operative characteristics. Optimization of intraoperative parameters and use of risk calculators may enable early institution of pharmacotherapy and improve overall outcome after cardiac surgery.

Air, inflammation and biocompatibility of the extracorporeal circuits

The inflammatory response in cardiac surgery using extracorporeal circulation (ECC) has been widely discussed in the literature with analysis on cytokines released in humans; demonstrating manifold trigger causes. To mitigate this response-mainly linked to the contact and recognition by the blood of a "non-self" surface-many efforts have been made to make the circuits of the extra-corporeal circulation "biomimetics"; trying to emulate the cardio-vascular system. In other words, biomedical companies have developed many biocompatible products in order to reduce the invasiveness of the ECC. One of the techniques used to reduce the contact of blood with "nonself" surfaces is the "coating" of the internal surfaces of the ECC. This can be done with phospholipidic, electrically neutral, and heparin derivates with anticoagulant activity. The coating can be divided into two categories: the "passive coating" with Phosphorylcholine by biomedical companies and the administration of albumin added to the "priming" during the filling of the circuit by the perfusionist. Alternatively, we have the "active" coating: treatment of the internal surfaces in contact with the blood with neutral proteins and heparin. The latter are different according to the production company, but the aim is always to maintain high levels of systemic and local anticoagulation, inactivating the "contact" coagulation between the blood and the surfaces. A recent study demonstrates that the use of an "active coating" is associated with better preservation of the endothelial glycocalyx compared with "passive coating" circuits.

A coronary cameral fistula treated with coil embolization

A 56-year-old man who had twice previously undergone orthotopic heart transplantation was admitted with dyspnea and heart failure symptoms. A biopsy excluded rejection. Left heart catheterization revealed a coronary cameral fistula. After the patient was given mild diuretics, his condition improved. No significant fistula flow was detected, and he was discharged. Several months later, the patient was readmitted with worsening chest pain and dyspnea. Left ventricular end-diastolic pressure and flow through the fistula were increased. To correct the coronary cameral fistula, we performed a coil embolization without complications. Several months later at follow-up, the patient’s symptoms had resolved, and his left ventricular end-diastolic pressure had normalized. We conclude that coronary fistulas may be caused by trauma to the heart during the de-airing process, which may be prevented in the future with the development of safer and more effective de-airing techniques.

Right anterolateral mini-thoracotomy without inferior vena cava cannulation for atrial septal defect repair in small children: A feasible technique

•

Minimally invasive cardiac surgery is limited in small children.

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Femoral cannulation has high risks in children with body weight <15 kg.

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7–12 cm skin incision called “mini-thoracotomy” was used with less cosmetic results.

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Reducing the length of incision without femoral cannulation needs new approach.

•

This technique is safe and feasible for atrial septal defect repair.

Objective

To evaluate the effectiveness and safety of right anterolateral mini-thoracotomy without inferior vena cava (IVC) cannulation for closing atrial septal defect (ASD) in small children.

Methods

From February 2016 to August 2017, 10 patients (the mean age was 18.5 ± 10.1 months and the mean weight was 8.3 ± 2.1 kg) underwent ASD closure via right anterolateral mini-thoracotomy. The superior vena cava cannula was placed through the right internal jugular vein. A 3–4 cm incision was made on the right chest. The pleural and pericardial cavities were filled with CO₂ and the heart was beating during the surgery. Blood returned from IVC was drained by a right heart sucker. All ASDs were closed using artificial patch, continuous suture. Mean follow-up was 18 months (range, 15–22 months).

Results

No post-operative complications or deaths occurred. Mean operation time and mean cardiopulmonary bypass time were 140.5 ± 27.8 min and 50.3 ± 16.5 min, respectively. These patients were extubated within the first 6 h. The intensive care unit stay time and the post-operative hospital stay time were 19.6 ± 2.6 h and 7.1 ± 1.2 days, respectively. Follow-up transthoracic echocardiography showed no residual shunts or lung atelectasis.

Conclusions

The right anterolateral mini-thoracotomy without IVC cannulation is feasible for repairing ASD in small children. This technique is effective and safe and can be used as a therapeutic option for ASD.

Totally endoscopic atrial septal defect repair using transthoracic aortic cannulation in a 10.5-kg-boy

INTRODUCTION

Although totally endoscopic surgery (TES) has been widely applied for the treatment of atrial septal defect (ASD), small children receive few benefits from this technique due to risks of the femoral cannulation.

CASE PRESENTATION

A 23-month-old boy, weighing 10.5 kg, with the diagnosis of sinus venosus ASD underwent successful repair by TES. We performed this surgery through 4 small trocars (one 12 mm trocar and three 5 mm trocars), without robotic assistance. In this case, we inserted the arterial cannula directly into the ascending aorta instead of the femoral artery (FA). The defects were repaired on the beating heart with CO₂ insufflation.

DISCUSSION

Femoral cannulation in small children pose some risks, such as increased arterial line pressure, critical lower limb ischaemia, and post-operative iliac or femoral arterial stenosis. Putting the arterial cannula directly into the ascending aorta is a good solution but is difficult to be performed through TES, especially in small children. The major concern of operating on the beating heart is the air embolism, which requires special preventative methods.

CONCLUSION

Transthoracic aortic cannulation may facilitate TES in small children. However, the safety and efficacy of this approach needs to be validated by larger studies preferably randomised controlled trials.

Effects of carbon dioxide insufflation on anastomosis remodeling at a carotid artery site in rabbits

Introduction

Use of carbon dioxide (CO₂) insufflation (CDI) on the surgical field during heart surgery has become widespread, and in some units routine.

Aim

To assess the effects of CDI on endothelial dysfunction in a carotid artery model in rabbits.

Material and methods

Twelve randomly selected rabbits were divided into two groups. Right carotid arteries of the animals were transected and sutured with running suture technique. Then, 1 l/min CO₂ insufflation was initiated with a 45° angle. In the control group, the anastomotic field was irrigated with 0.1 ml/s flow of 0.9% saline. At day 28, the carotid artery segments were removed and prepared for histological specimens.

Results

In the cross-sections of the control group vessel samples, thickening of the tunica intima was observed. Scoring the quantity of endothelial nitric oxide synthase (e-NOS) and α-smooth muscle actin (α-SMA) positive staining revealed a nonsignificant difference between the experimental groups (p = 0.07). In the CO₂ group, the intimal hyperplasia (p = 0.2) and the thickness of the tunica media (p = 0.2) were indistinguishable when compared to the control group. The mean luminal diameters and luminal areas of the experimental groups were all evaluated by histomorphometry and a significant differences was found between luminal areas (p = 0.016). On the other hand, no significant difference was found between mean luminal diameters (p = 0.055).

Conclusions

Our study indicated that CDI can affect endothelial cell damage and the mean luminal diameters.

Cognitive Outcomes After Heart Valve Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

To summarize evidence on cognitive outcomes after heart valve surgery; secondary aim, to examine whether aortic and mitral valve surgery are associated with different cognitive outcomes.

DESIGN

Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review and meta-analysis.

SETTING

Cardiac surgery.

PARTICIPANTS

Individuals undergoing heart valve surgery.

MEASUREMENTS

We searched MEDLINE, EMBASE, and PsycINFO for peer-reviewed reports of individuals undergoing heart valve surgery who underwent pre- and postoperative cognitive assessment. Our initial search returned 1,475 articles, of which 12 were included. Postoperative cognitive results were divided into those from 1 week to 1 month (early outcomes, n_pooled  = 450) and from 2 to 6 months (intermediate outcomes; n_pooled  = 722). No studies with longer-term outcomes were identified.

RESULTS

Subjects had moderate early cognitive decline from baseline (Becker mean gain effect size (ES)=-0.39 ± 0.27) that improved slightly by 2 to 6 months (ES=-0.25 ± 0.38). Individuals undergoing aortic valve surgery-who were older on average than those undergoing mitral valve surgery (68 vs 57)-had greater early cognitive decline than those undergoing mitral valve surgery (ES=-0.68 vs -0.12), but both cohorts had similar decline 2 to 6 months postoperatively (ES=-0.27 vs -0.20).

CONCLUSIONS

Heart valve surgery is associated with cognitive decline over the 6 months after surgery, but outcomes beyond 6 months are unclear. These findings highlight the cognitive vulnerability of this population, especially older adults with aortic stenosis. © 2018 American Geriatrics Society and Wiley Periodicals, Inc. J Am Geriatr Soc 66:2327-2334, 2018.

The influence of carbon dioxide field flooding in mitral valve operations with cardiopulmonary bypass on S100ß level in blood plasma in the aging brain

Introduction

The risk of air microembolism during cardiopulmonary bypass (CPB) is high and influences the postoperative outcome, especially in elderly patients. The use of carbon dioxide (CO₂) atmosphere during cardiac surgery may reduce the risk of cerebral air microembolism. The aim of our study was to assess the influence of CO₂ field flooding on microembolism-induced brain damage assessed by the level of S100ß protein, regarded as a marker of brain damage.

Materials and methods

A group of 100 patients undergoing planned mitral valve operation through median sternotomy using standard CPB was recruited for the study. Echocardiography was performed prior to and after the CPB. CO₂ insufflation at 6 L/minute was conducted in the study group. Blood samples for S100ß protein analysis were collected after induction of anesthesia, 2 hours after aorta de-clamping, and 24 hours after operation.

Results

The S100ß level in blood plasma did not differ significantly between the study and the control group (0.13±0.08 µg/L, 1.12±0.59 µg/L, and 0.26±0.23 µg/L and 0.18±0.19 µg/L, 1.31±0.62 µg/L, and 0.23±0.12 µg/L, P=0.7, 0.14, and 0.78). The mean increase of the S100ß concentration was 13% lower in the group with CO₂ protection than in the control group (0.988 µg/L vs 1.125 µg/L), although statistically insignificant. Tricuspid valve annuloplasties (TVAs) had significant impact on the increase in S100ß concentration in the treatment group after 24 hours (TVA [−] 0.21±0.09 vs TVA [+] 0.42±0.42, P=0.05). In patients <60 years, there were significant differences in the S100ß level 2 and 24 hours after the procedure (1.59±0.682 µg/L vs 1.223±0.571 µg/L, P=0.048, and 0.363±0.318 µg/L vs 0.229±0.105 µg/L, P=0.036) as compared with younger patients.

Conclusion

The increase in S100ß concentration was lower in the group with CO₂ protection than in the control group. Age and an addition of TVA significantly influenced the level of S100ß concentration in the tests performed 2 hours after aortic clamp release.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Totally Endoscopic Cardiac Surgery for Atrial Septal Defect Repair on Beating Heart Without Robotic Assistance in 25 Patients

Supplemental digital content is available in the text.

Objective

The aim of the study was to investigate the effectivity and safety of totally endoscopic cardiac surgery without robotic assistance for atrial septal defect (ASD) closure on beating hearts.

Methods

Twenty-five patients (adults/children: 15/10) underwent ASD closure using nonrobotically assisted totally endoscopic approach on beating heart. Three 5-mm trocars and one 12-mm trocar were used, only the superior vena cava is snared, filling the pleural and pericardial cavities with CO₂, and the heart was beating during the surgery. Twenty-three patients had isolated secundum ASD (2 of which had severe tricuspid regurgitation) and two patients had ASD combined with partial anomalous pulmonary venous connection. All ASDs were closed using artificial patch, continuous suture; tricuspid regurgitations were repaired and the anomalous pulmonary veins were drained to the left atrium.

Results

No postoperative complications or deaths occurred. Mean ± SD operation time and mean cardiopulmonary bypass time were 267.2 ± 44.6 and 156.1 ± 33.6 min, respectively. These patients were extubated within the first 5 hours, and the volume of blood drainage on the first day was less than 80 mL. Four days after surgery, patients did not need analgesics and were able to return to normal activities 1 week postoperatively.

Conclusions

Totally endoscopic operation for ASD closure on beating heart is safe, with short recovery period, and surgical scars are of high cosmetic value, especially in a woman and girl.

Pulmonary collapse alone provides effective de-airing in cardiac surgery: a prospective randomized study

OBJECTIVES

We previously described and showed that the method for cardiac de-airing involving: (1) bilateral, induced pulmonary collapse by opening both pleurae and disconnecting the ventilator before cardioplegic arrest and (2) gradual pulmonary perfusion and ventilation after cardioplegic arrest is superior to conventional de-airing methods, including carbon dioxide insufflation of the open mediastinum. This study investigated whether one or both components of this method are responsible for the effective de-airing of the heart.

METHODS

Twenty patients scheduled for open, left heart surgery were randomized to two de-airing techniques: (1) open pleurae, collapsed lungs and conventional pulmonary perfusion and ventilation; and (2) intact pleurae, expanded lungs and gradual pulmonary perfusion and ventilation.

RESULTS

The number of cerebral microemboli measured by transcranial Doppler sonography was lower in patients with open pleurae 9 (6-36) vs 65 (36-210), p = 0.004. Residual intra-cardiac air grade I or higher as monitored by transesophageal echocardiography 4-6 minutes after weaning from cardiopulmonary bypass was seen in few patients with open pleurae 0 (0%) vs 7 (70%), p = 0.002.

CONCLUSIONS

Bilateral, induced pulmonary collapse alone is the key factor for quick and effective de-airing of the heart. Gradual pulmonary perfusion and ventilation, on the other hand, appears to be less important.

Size distribution of air bubbles entering the brain during cardiac surgery

Background

Thousands of air bubbles enter the cerebral circulation during cardiac surgery, but whether high numbers of bubbles explain post-operative cognitive decline is currently controversial. This study estimates the size distribution of air bubbles and volume of air entering the cerebral arteries intra-operatively based on analysis of transcranial Doppler ultrasound data.

Methods

Transcranial Doppler ultrasound recordings from ten patients undergoing heart surgery were analysed for the presence of embolic signals. The backscattered intensity of each embolic signal was modelled based on ultrasound scattering theory to provide an estimate of bubble diameter. The impact of showers of bubbles on cerebral blood-flow was then investigated using patient-specific Monte-Carlo simulations to model the accumulation and clearance of bubbles within a model vasculature.

Results

Analysis of Doppler ultrasound recordings revealed a minimum of 371 and maximum of 6476 bubbles entering the middle cerebral artery territories during surgery. This was estimated to correspond to a total volume of air ranging between 0.003 and 0.12 mL. Based on analysis of a total of 18667 embolic signals, the median diameter of bubbles entering the cerebral arteries was 33 μm (IQR: 18 to 69 μm). Although bubble diameters ranged from ~5 μm to 3.5 mm, the majority (85%) were less than 100 μm. Numerous small bubbles detected during cardiopulmonary bypass were estimated by Monte-Carlo simulation to be benign. However, during weaning from bypass, showers containing large macro-bubbles were observed, which were estimated to transiently affect up to 2.2% of arterioles.

Conclusions

Detailed analysis of Doppler ultrasound data can be used to provide an estimate of bubble diameter, total volume of air, and the likely impact of embolic showers on cerebral blood flow. Although bubbles are alarmingly numerous during surgery, our simulations suggest that the majority of bubbles are too small to be harmful.