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

Improving Trendelenburg position effectiveness by varying cardiopulmonary bypass flow

INTRODUCTION

Trendelenburg position (TP) is used to transport gaseous emboli away from the cerebral region during cardiac surgery. However, TP effectiveness has not been fully considered when combined with varying the cardiopulmonary bypass (CPB) flow. This study simulated the supine and TP at different pump flows and assessed the trapped emboli and embolic load entering the aortic arch branch arteries (AABA).

METHODS

A computational fluid dynamics (CFD) approach used a centrally cannulated adult patient-specific aorta model replicating a CPB circuit. Air emboli of 0.1 mm, 0.5 mm, and 1.0 mm (n = 700 each) were injected into the aorta placed in the supine position (0°) and the TP (-20°) at 2 L/min and 5 L/min. The number of emboli entering the AABA were compared. An aortic phantom flow experiment was performed to validate air bubble behaviour.

RESULTS

TP at 5 L/min had the lowest 0.1 mm mean (±SD) embolic load compared to the supine 2 L/min (55.3 ± 30.8 vs 64.3 ± 35.4). For both the supine and TP, the lower flow of 2 L/min had the highest number of simulated trapped emboli in higher elevated regions than at 5 L/min (541 ± 185 and 548 ± 191 vs 520 ± 159 and 512 ± 174), respectively. The flow experiment demonstrated that 2 L/min promoted bubble coalescence and high amounts of trapped emboli and 5 L/min transported air emboli away from the AABA.

CONCLUSIONS

TP effectiveness was improved by using CPB flow to manage air emboli. These results provide insights for predicting emboli behaviour and improving emboli de-airing procedures.

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.

Brain Protection in the Endo-Management of Proximal Aortic Aneurysms

Neurological brain injury (NBI) remains the most feared complication following thoracic endovascular aortic repair (TEVAR), and can manifest as clinically overt stroke and/or more covert injury, detected only on explicit neuropsychological testing. Microembolic signals (MES) detected on transcranial Doppler (TCD) monitoring of the cerebral arteries during TEVAR and the high prevalence and incidence of new ischaemic infarcts on diffusion-weighted magnetic resonance imaging (DW-MRI) suggests procedure-related solid and gaseous cerebral microembolisation to be an important cause of NBI. Any intervention that can reduce the embolic burden during TEVAR may, therefore, help mitigate the risk of stroke and the covert impact of ischaemic infarcts to the function of the brain. This perspective article provides an understanding of the mechanism of stroke and reviews the available evidence regarding potential neuroprotective strategies that target high-risk procedural steps of TEVAR to reduce periprocedural cerebral embolisation.

Systematic preoperative CT scan is associated with reduced risk of stroke in minimally invasive mitral valve surgery: A meta-analysis

BACKGROUND

Minimally invasive mitral valve surgery (MIMVS) is performed with increasing frequency. However, patients undergoing MIMVS might be at increased risk of perioperative stroke, mainly due to retrograde aortic embolization during femoral cardio-pulmonary bypass. Pre-operative computed tomography (CT) screening allows visualization of the aorta and femoro-iliac vessels and individualization of the surgical approach. In this meta-analysis, we aim to determine if systematic pre-operative CT screening is associated with decreased incidence of post-operative stroke and other complications following MIMVS.

METHODS

A comprehensive review was performed in PubMed (inception-May 2018). Eligible studies included those which reported on MIMVS (mini-thoracotomy, port access or robotic approach) with retrograde arterial perfusion. Studies were separated into two subgroups: systematic pre-operative CT screening (CT-group) and no CT screening (Non-CT). Pooled event rates (PER) for operative mortality, post-operative stroke, perioperative myocardial infarction (MI), and new onset renal failure requiring dialysis were estimated and inter-group comparisons were performed.

RESULTS

Data from 57 studies (13,731 patients) were analyzed (19 CT-group, 38 Non-CT). PER for post-operative stroke was 2.0% with a statistically significant difference between the groups (CT-group: 1.5% versus Non-CT: 2.2%, P = 0.03). PER for new dialysis was 1.9%, significantly lower in the CT-group (0.8% versus 2.3% in the Non-CT group, P = 0.02). PER for operative mortality was 1.4% with a trend towards better outcomes in the CT-group (0.8% versus 1.6% in the Non-CT group, P = 0.05).

CONCLUSIONS

Systematic pre-operative CT screening is associated with lower risk of post-operative stroke and need for dialysis and a trend toward lower operative mortality after MIMVS.